Evaluation of cephamycins as supplements to selective agar for detecting Campylobacter spp. in chicken carcass rinses.

PubMed

Chon, Jung-Whan; Kim, Young-Ji; Kim, Hong-Seok; Kim, Dong-Hyeon; Kim, Hyunsook; Song, Kwang-Young; Sung, Kidon; Seo, Kun-Ho

2016-04-16

Although cefoperazone is the most commonly used antibiotic in Campylobacter-selective media, the distribution of cefoperazone-resistant bacteria such as extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is increasing. Here we evaluated the potential of cephamycins for use as supplements to improve modified charcoal-cefoperazone-deoxycholate agar (mCCDA) by replacing cefoperazone with the same concentrations (32 mg/L) of cefotetan (modified charcoal-cefotetan-deoxycholate agar, mCCtDA) and cefoxitin (modified charcoal-cefoxitin-deoxycholate agar, mCCxDA). In chicken carcass rinse samples, the number of mCCDA plates detecting for Campylobacter (18/70, 26%) was significantly lower than that of mCCtDA (42/70, 60%) or mCCxDA plates (40/70, 57%). The number of mCCDA plates (70/70, 100%) that were contaminated with non-Campylobacter species was significantly higher than that of mCCtDA (20/70, 29%) or mCCxDA plates (21/70, 30%). The most common competing species identified using mCCDA was ESBL-producing E. coli, while Pseudomonas species frequently appeared on mCCtDA and mCCxDA. Copyright © 2016. Published by Elsevier B.V.

Colony formation by sublethally heat-injured Zygosaccharomyces rouxii as affected by solutes in the recovery medium and procedure for sterilizing medium.

PubMed Central

Golden, D A; Beuchat, L R

1990-01-01

Recovery and colony formation by healthy and sublethally heat-injured cells of Zygosaccharomyces rouxii as influenced by the procedure for sterilizing recovery media (YM agar [YMA], wort agar, cornmeal agar, and oatmeal agar) were investigated. Media were supplemented with various concentrations of glucose, sucrose, glycerol, or sorbitol and sterilized by autoclaving (110 degrees C, 15 min) and by repeated treatment with steam (100 degrees C). An increase in sensitivity was observed when heat-injured cells were plated on glucose-supplemented YMA at an aw of 0.880 compared with aws of 0.933 and 0.998. Colonies which developed from unheated and heated cells on YMA at aws of 0.998 and 0.933 generally exceeded 0.5 mm in diameter within 3.5 to 4 days of incubation at 25 degrees C, whereas colonies formed on YMA at an aw of 0.880 typically did not exceed 0.5 mm in diameter until after 5.5 to 6.5 days of incubation. The number of colonies exceeding 0.5 mm in diameter which were formed by heat-injured cells on YMA at an aw of 0.880 was 2 to 3 logs less than the total number of colonies detected, i.e., on YMA at an aw of 0.933 and using no limits of exclusion based on colony diameter. A substantial portion of cells which survived heat treatment were sublethally injured as evidenced by increased sensitivity to a suboptimum aw (0.880). In no instance was recovery of Z. rouxii significantly affected by medium sterilization procedure when glucose or sorbitol was used as the aw-suppressing solute.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2403251

Colony formation by sublethally heat-injured Zygosaccharomyces rouxii as affected by solutes in the recovery medium and procedure for sterilizing medium.

PubMed

Golden, D A; Beuchat, L R

1990-08-01

Recovery and colony formation by healthy and sublethally heat-injured cells of Zygosaccharomyces rouxii as influenced by the procedure for sterilizing recovery media (YM agar [YMA], wort agar, cornmeal agar, and oatmeal agar) were investigated. Media were supplemented with various concentrations of glucose, sucrose, glycerol, or sorbitol and sterilized by autoclaving (110 degrees C, 15 min) and by repeated treatment with steam (100 degrees C). An increase in sensitivity was observed when heat-injured cells were plated on glucose-supplemented YMA at an aw of 0.880 compared with aws of 0.933 and 0.998. Colonies which developed from unheated and heated cells on YMA at aws of 0.998 and 0.933 generally exceeded 0.5 mm in diameter within 3.5 to 4 days of incubation at 25 degrees C, whereas colonies formed on YMA at an aw of 0.880 typically did not exceed 0.5 mm in diameter until after 5.5 to 6.5 days of incubation. The number of colonies exceeding 0.5 mm in diameter which were formed by heat-injured cells on YMA at an aw of 0.880 was 2 to 3 logs less than the total number of colonies detected, i.e., on YMA at an aw of 0.933 and using no limits of exclusion based on colony diameter. A substantial portion of cells which survived heat treatment were sublethally injured as evidenced by increased sensitivity to a suboptimum aw (0.880). In no instance was recovery of Z. rouxii significantly affected by medium sterilization procedure when glucose or sorbitol was used as the aw-suppressing solute.(ABSTRACT TRUNCATED AT 250 WORDS)

Prospective Comparison of a New Chromogenic Medium, MRSASelect, to CHROMagar MRSA and Mannitol-Salt Medium Supplemented with Oxacillin or Cefoxitin for Detection of Methicillin-Resistant Staphylococcus aureus

PubMed Central

Stoakes, Luba; Reyes, Romina; Daniel, Janis; Lennox, Gwen; John, Michael A.; Lannigan, Robert; Hussain, Zafar

2006-01-01

MRSASelect agar was compared to CHROMagar, mannitol-salt agar with oxacillin, and mannitol-salt agar with cefoxitin (MSA-CFOX) for the isolation of methicillin-resistant Staphylococcus aureus (MRSA). The sensitivities and specificities were 97.3% and 99.8%, 82.9% and 99.1%, 80.2% and 79%, and 99.1% and 84.8%, respectively. MSA-CFOX and MRSASelect had a high sensitivity. MRSASelect, however, was more specific and proved to be a more reliable and rapid medium for the detection of MRSA. PMID:16455933

Detection of Fusobacterium nucleatum in two cases of empyema and lung abscess using paromomycin-vancomycin supplemented Brucella HK agar.

PubMed

Nagaoka, Kentaro; Yanagihara, Katsunori; Morinaga, Yoshitomo; Kohno, Shigeru

2017-02-01

Fusobacterium nucleatum was found in patients with empyema or pulmonary abscess, using paromomycin-vancomycin Brucella HK agar. In vitro examination revealed that growth of the strains differed significantly in different media. Clinicians should be aware that suboptimal F. nucleatum cultivation methods may result in an underestimation of its frequency. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anticlostridial agent 8-hydroxyquinoline improves the isolation of faecal bifidobacteria on modified Wilkins-Chalgren agar with mupirocin.

PubMed

Novakova, J; Vlkova, E; Salmonova, H; Pechar, R; Rada, V; Kokoska, L

2016-04-01

The need for suitable selective cultivation media for the isolation of Bifidobacterium spp. continues to be a real concern in the field of intestinal microbiology. Isolation of bifidobacteria from human and animal faecal samples using selective agar plating may be problematic especially in samples with increased clostridial counts than bifidobacterial counts. Due to the absence of anticlostridial agents in existing selective media, clostridia can displace bifidobacteria resulting in incorrect estimation of their counts. Therefore, we supplemented the existing selective medium 'modified Wilkins Chalgren agar with mupirocin' (MWM) with 90 mg l(-1) of 8-hydroxyquinoline (8HQ), which was recently proved to act selectively against clostridia. The newly composed 'modified Wilkins-Chalgren agar with 8HQ' (MWMQ) was tested on pure bifidobacterial and clostridial strains, their mixtures, and using faecal samples of mammalian origin; its selectivity was evaluated by genus-specific identification of isolates. The results demonstrated that the presence of 8HQ in this agar eliminated the growth of nonbifidobacterial strains on MWMQ compared to that on MWM, whereas the recovery of bifidobacterial counts was at satisfactory levels. In conclusion, MWMQ could be recommended for bifidobacterial isolation from human and animal faeces especially when bifidobacteria are not numerically dominant and there are chances of clostridial contamination. Routine isolation of bifidobacteria from mammalian faeces does not use a reliable selective agar with an anticlostridial agent. Overgrowth of clostridia may result in incorrect estimation of bifidobacterial counts. Thus, in order to improve the selectivity of existing media for bifidobacterial isolation, we chose the modified Wilkins-Chalgren agar with mupirocin and supplemented it with 8-hydroxyquinoline (8HQ), a molecule that shows anticlostridial activity without affecting the growth of bifidobacteria. This newly composed medium showed enhanced selectivity and specificity compared to the original medium and therefore, can be recommended for the isolation of bifidobacteria from mammal faeces. © 2016 The Society for Applied Microbiology.

Protocol for the Meningococcal Control Programme - Canadian Forces Base Cornwallis and Canadian Forces Base St. Jean 1980/81,

DTIC Science & Technology

1980-11-01

hours, then overnight in a refrigerator or cold room at 40C. Fol- lowing clot retraction , the serum may be decanted and spun, or the whole sample spun...Drogram. The SIMP programme may involve one or all of the following: collection of post nasal swabs, blood sera samples, air samples and surface samples...outlined in para 16. 16. Culturing of Swabs Swabs shall be placed on Columbia Blood Agar (4 or 5% sheep RBC’s) supplemented with IsoVitalex (Baltimore

Dietary fibre supplementation of a 'normal' breakfast administered to diabetics.

PubMed

Williams, D R; James, W P; Evans, I E

1980-05-01

The supplementation of a breakfast by 10 g of guar, pectin, agar or locust bean gum in powder form in 13 maturity onset, non-insulin dependent diabetics failed to decrease significantly the post-prandial rise in plasma glucose and insulin seen after a similar meal without the supplement. The values of one hour post-prandial increment in blood glucose seen with guar powder were, for control meal (mean +/- SEM) 5.8 %/- 0.4 mmol/l, for test, 5.7 +/- 0.5; with pectin powder, control 6.4 +/- 0.8 mmol/l, test 5.0 +/- 1.2 mmol/l; with agar powder, control 7.5 +/- 1.0, test 7.0 +/- 0.5; with locust bean gum powder, control 5.9 +/- 1.0, test 5.0 +/- 0.7. The equivalent values for one hour insulin (microU/ml, mean +/- SEM) were, for guar powder, 51 +/0 21 and 51 +/- 16; for pectin powder 60 +/- 24 and 63 +/- 17; for agar powder, 27 +/- 9 and 36 +/- 11 and, for locust bean gum powder 53 +/- 26 and 62 +/- 18. The guar, pectin and locust gum tended to form lumps, and all the substances tested were unpalatable in powder form producing feelings of abdominal discomfort and abnormal fullness. Administering the same quantity of guar or pectin in a well hydrated form (but not premixed with the carbohydrate portion of the food) to the same people under identical conditions did not enhance its effectiveness. Supplementing diets with any of these sources of dietary fibre in either of these forms and in these amounts is unlikely to be beneficial in the management of non-insulin dependent diabetes.

Characterization of the species Malassezia pachydermatis and re-evaluation of its lipid dependence using a synthetic agar medium

PubMed Central

Puig, Laura; Castellá, Gemma

2017-01-01

The genus Malassezia includes lipophilic yeasts, which are part of the skin microbiota of various mammals and birds. Unlike the rest of Malassezia species, M. pachydermatis is described as non-lipid-dependent, as it is able to grow on Sabouraud glucose agar (SGA) without lipid supplementation. In this study we have examined the phenotypic variability within M. pachydermatis and confirmed its lipid-dependent nature using a synthetic agar medium. We used a selection of representative non-lipid-dependent strains from different animal species and three atypical lipid-dependent strains of this species, which were not able to grow after multiple passages on SGA. More than 400 lipid-dependent Malassezia isolates from animals were studied in order to detect the three lipid-dependent strains of M. pachydermatis. The identity of the atypical strains was confirmed by DNA sequencing. On the other hand, we have modified the Tween diffusion test, which is widely used in the characterization of these yeasts, by using a synthetic agar-based medium instead of SGA. This modification has proved to be useful for differentiation of M. pachydermatis strains, providing reproducible results and a straightforward interpretation. The finding of these peculiar lipid-dependent strains exemplifies the large variability within the species M. pachydermatis, which involves rare atypical strains with particular growth requirements. PMID:28586389

Characterization of the species Malassezia pachydermatis and re-evaluation of its lipid dependence using a synthetic agar medium.

PubMed

Puig, Laura; Bragulat, M Rosa; Castellá, Gemma; Cabañes, F Javier

2017-01-01

The genus Malassezia includes lipophilic yeasts, which are part of the skin microbiota of various mammals and birds. Unlike the rest of Malassezia species, M. pachydermatis is described as non-lipid-dependent, as it is able to grow on Sabouraud glucose agar (SGA) without lipid supplementation. In this study we have examined the phenotypic variability within M. pachydermatis and confirmed its lipid-dependent nature using a synthetic agar medium. We used a selection of representative non-lipid-dependent strains from different animal species and three atypical lipid-dependent strains of this species, which were not able to grow after multiple passages on SGA. More than 400 lipid-dependent Malassezia isolates from animals were studied in order to detect the three lipid-dependent strains of M. pachydermatis. The identity of the atypical strains was confirmed by DNA sequencing. On the other hand, we have modified the Tween diffusion test, which is widely used in the characterization of these yeasts, by using a synthetic agar-based medium instead of SGA. This modification has proved to be useful for differentiation of M. pachydermatis strains, providing reproducible results and a straightforward interpretation. The finding of these peculiar lipid-dependent strains exemplifies the large variability within the species M. pachydermatis, which involves rare atypical strains with particular growth requirements.

Probiotic culture survival and implications in fermented frozen yogurt characteristics.

PubMed

Davidson, R H; Duncan, S E; Hackney, C R; Eigel, W N; Boling, J W

2000-04-01

Low-fat ice cream mix was fermented with probiotic-supplemented and traditional starter culture systems and evaluated for culture survival, composition, and sensory characteristics of frozen product. Fermentations were stopped when the titratable acidity reached 0.15% greater than the initial titratable acidity (end point 1) or when the pH reached 5.6 (end point 2). Mix was frozen and stored for 11 wk at -20 degrees C. The traditional yogurt culture system contained the strains Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus. The probiotic-supplemented system contained the traditional cultures as well as Bifidobacterium longum and Lactobacillus acidophilus. We compared recovery of Bifodobacterium by three methods, a repair-detection system with roll-tubes and plates on modified bifid glucose medium and plates with maltose + galactose reinforced clostridial medium. Culture bacteria in both systems did not decrease in the yogurt during frozen storage. The roll-tube method with modified bifid glucose agar and repair detection system provided at least one-half log10 cfu/ml higher recovery of B. longum compared with recoveries using modified bifid glucose agar or maltose + galactose reinforced clostridial agar on petri plates. No change in concentrations of lactose or protein for products fermented with either culture system occurred during storage. Acid flavor was more intense when product was fermented to pH 5.6, but yogurt flavor was not intensified. The presence of probiotic bacteria in the supplemented system seemed to cause no differences in protein and lactose concentration and sensory characteristics.

Culture of bovine embryos in deproteinized hemodialysate-supplemented media and immature mouse uterine horns.

PubMed

Thuemmel, A E; Gwazdauskas, F C; Canseco, R S; Pearson, R E; Jochle, W

1991-06-01

Bovine morulae (d 6) were used to evaluate embryonic development in a deproteinized hemodialysate, agar embedding, and in the uterus of the immature mouse. Agar-embedded embryos were cultured in Ham's F-10 and 10% steer serum either (treatment 1) immediately after collection or (treatment 2) 24 h after storage in the uterus of the immature mouse. Unembedded embryos were cultured in Ham's F-10 containing (treatment 3) 10% steer serum, (treatment 4) 1% deproteinized hemodialysate CLB1107, or (treatment 5) 1% de-proteinized hemodialysate CLB1107 and 10% steer serum. A greater percentage of the embryos reached the hatched blastocyst stage after culture in treatments 1, 3, 4, and 5 (38.1, 34.6, 28.6, and 21.1%) than in treatment 2 (9.5%) in which embryos were stored in the immature mouse uterus for 24 h prior to in vitro culture. Final development scores for unembedded and agar-embedded embryos cultured in Ham's F-10 (5.5 +/- .3) and 10% steer serum (4.9 +/- .4) were similar and higher than those of embryos cultured in deproteinized hemodialysate CLB1107 (4.2 +/- .4), deproteinized hemodialysate CLB1107 and steer serum (4.2 +/- .4), or immature mouse uteri (3.4 +/- .4). It is concluded that deproteinized hemodialysate supplementation at 1% (vol/vol) failed to enhance embryonic development in vitro. Moreover, bovine morulae were unaffected by agar embedding and were able to develop to a limited extent following short-term storage in the uterus of the immature mouse.

An improved procedure for shipboard enumeration of faecal indicator bacteria in marine sediments from sewage sludge disposal areas.

PubMed

West, P A

1988-04-01

An improved membrane filtration procedure for use on board ship to enumerate Escherichia coli and Group D faecal streptococci in marine sediments is described. Ultrasonication extraction combined with resuscitation of sublethally-injured cells yielded significantly higher counts of E. coli than sediments shaken by hand. Counts of E. coli were also higher on mFC agar (without rosalic acid) after a period of resuscitation on tryptone-soy agar supplemented with 0.1% yeast extract than on a 4% Teepol-lactose medium. Ultrasonication of sediments made no significant difference to counts of Group D faecal streptococci on KF-streptococcus agar. These improved isolation procedures allowed better discrimination of the area affected by sewage sludge at a disposal site off the northeast coast of England.

40 CFR 141.21 - Coliform sampling.

Code of Federal Regulations, 2014 CFR

2014-07-01

... water) with the intent that if the method they choose has an unacceptable false-positive or negative...), supplemented with 100 µg/mL of MUG. If the 18th edition is used, incubate the agar plate at 35 °C for 4 hours...

40 CFR 141.21 - Coliform sampling.

Code of Federal Regulations, 2012 CFR

2012-07-01

... water) with the intent that if the method they choose has an unacceptable false-positive or negative...), supplemented with 100 µg/mL of MUG. If the 18th edition is used, incubate the agar plate at 35 °C for 4 hours...

40 CFR 141.21 - Coliform sampling.

Code of Federal Regulations, 2013 CFR

2013-07-01

... water) with the intent that if the method they choose has an unacceptable false-positive or negative...), supplemented with 100 µg/mL of MUG. If the 18th edition is used, incubate the agar plate at 35 °C for 4 hours...

The fungicidal and phytotoxic properties of benomyl and PPM in supplemented agar media supporting transgenic arabidopsis plants for a Space Shuttle flight experiment

NASA Technical Reports Server (NTRS)

Paul, A. L.; Semer, C.; Kucharek, T.; Ferl, R. J.

2001-01-01

Fungal contamination is a significant problem in the use of sucrose-enriched agar-based media for plant culture, especially in closed habitats such as the Space Shuttle. While a variety of fungicides are commercially available, not all are equal in their effectiveness in inhibiting fungal contamination. In addition, fungicide effectiveness must be weighed against its phytotoxicity and in this case, its influence on transgene expression. In a series of experiments designed to optimize media composition for a recent shuttle mission, the fungicide benomyl and the biocide "Plant Preservative Mixture" (PPM) were evaluated for effectiveness in controlling three common fungal contaminants, as well as their impact on the growth and development of arabidopsis seedlings. Benomyl proved to be an effective inhibitor of all three contaminants in concentrations as low as 2 ppm (parts per million) within the agar medium, and no evidence of phytotoxicity was observed until concentrations exceeded 20 ppm. The biocide mix PPM was effective as a fungicide only at concentrations that had deleterious effects on arabidopsis seedlings. As a result of these findings, a concentration of 3 ppm benomyl was used in the media for experiment PGIM-01 which flew on shuttle Columbia mission STS-93 in July 1999.

Selective and differential enumerations of Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium spp. in yoghurt--a review.

PubMed

Ashraf, Rabia; Shah, Nagendra P

2011-10-03

Yoghurt is increasingly being used as a carrier of probiotic bacteria for their potential health benefits. To meet with a recommended level of ≥10(6) viable cells/g of a product, assessment of viability of probiotic bacteria in market preparations is crucial. This requires a working method for selective enumeration of these probiotic bacteria and lactic acid bacteria in yoghurt such as Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lb. acidophilus, Lb. casei and Bifidobacterium. This chapter presents an overview of media that could be used for differential and selective enumerations of yoghurt bacteria. De Man Rogosa Sharpe agar containing fructose (MRSF), MRS agar pH 5.2 (MRS 5.2), reinforced clostridial prussian blue agar at pH 5.0 (RCPB 5.0) or reinforced clostridial agar at pH 5.3 (RCA 5.3) are suitable for enumeration of Lb. delbrueckii subsp. bulgaricus when the incubation is carried out at 45°C for 72h. S. thermophilus (ST) agar and M17 are recommended for selective enumeration of S. thermophilus. Selective enumeration of Lb. acidophilus in mixed culture could be made in Rogosa agar added with 5-bromo-4-chloro-3-indolyl-β-d-glucopyranoside (X-Glu) or MRS containing maltose (MRSM) and incubation in a 20% CO2 atmosphere. Lb. casei could be selectively enumerated on specially formulated Lb. casei (LC) agar from products containing yoghurt starter bacteria (S. thermophilus and Lb. delbrueckii subsp. bulgaricus), Lb. acidophilus, Bifidobacterium spp. and Lb. casei. Bifidobacterium could be enumerated on MRS agar supplemented with nalidixic acid, paromomycin, neomycin sulphate and lithium chloride (MRS-NPNL) under anaerobic incubation at 37°C for 72h. Copyright © 2011. Published by Elsevier B.V.

Evaluation of culture media for counts of Bifidobacterium animalis subsp. lactis Bb 12in yoghurt after refrigerated storage.

PubMed

Fachin, Luciano; Moryia, Juliana; Neves Gândara, Ana Lourdes; Viotto, Walkiria Hanada

2008-04-01

The agar RCPB pH5 has been considered a good alternative for counts of Bifidobacterium in yoghurt. However, during the refrigerated storage of yoghurt it is extremely difficult to count this microorganism due to the size of the colonies, which are so small they require the aid of a stereoscope to count them. Another agar, MRS-LP, has been also recommended for counts of Bifidobacterium in the presence of yoghurt bacteria. This study evaluated the supplementation of RCPB pH5 agar with dehydrated liver extract and the salts KH2PO4, K2HPO4, FeSO47H2O, MnSO4H2O and MgSO47H2O, aiming at improving the differentiation of Bifidobacterium in yoghurt after refrigerated storage, and also evaluated the selective count of Bifidobacterium in yoghurt using the agar MRS-LP. The agar MRS-LP presented the same cell recovery as non-fortified RCPB pH5 agar, used as a standard medium, thus being considered a good option for counts of Bifidobacterium in yoghurt. The fortified RCPB pH5 also presented the same recovery as the standard RCPB pH5 medium, however, the addition of dehydrated liver extract to the RCPB pH5 agar considerably increased the size of the Bifidobacterium colonies after refrigerated storage, making differentiation of the colonies much easier and reliable when compared to the standard non-fortified RPCP pH5. The addition of the salts (KH2PO4, K2HPO4, FeSO47H2O, MnSO4H2O and MgSO47H2O) had no influence on the performance of the RCPB pH5 agar.

Effects of zinc supplementation on Shiga toxin 2e-producing Escherichia coli in vitro.

PubMed

Uemura, Ryoko; Katsuge, Tomoko; Sasaki, Yosuke; Goto, Shinya; Sueyoshi, Masuo

2017-10-07

Swine edema disease is caused by Shiga toxin (Stx) 2e-producing Escherichia coli (STEC). Addition of highly concentrated zinc formulations to feed has been used to treat and prevent the disease, but the mechanism of the beneficial effect is unknown. The purpose of the present study was to investigate the effects of highly concentrated zinc formulations on bacterial growth, hemolysin production, and an Stx2e release by STEC in vitro. STEC strain MVH269 isolated from a piglet with edema disease was cultured with zinc oxide (ZnO) or with zinc carbonate (ZnCO 3 ), each at up to 3,000 ppm. There was no effect of zinc addition on bacterial growth. Nonetheless, the cytotoxic activity of Stx2e released into the supernatant was significantly attenuated in the zinc-supplemented media compared to that in the control, with the 50% cytotoxic dose values of 163.2 ± 12.7, 211.6 ± 33.1 and 659.9 ± 84.2 after 24 hr of growth in the presence of ZnO, ZnCO 3 , or no supplemental zinc, respectively. The hemolytic zones around colonies grown on sheep blood agar supplemented with zinc were significantly smaller than those of colonies grown on control agar. Similarly, hemoglobin absorbance after exposure to the supernatants of STEC cultures incubated in sheep blood broth supplemented with zinc was significantly lower than that resulting from exposure to the control supernatant. These in vitro findings indicated that zinc formulations directly impair the factors associated with the virulence of STEC, suggesting a mechanism by which zinc supplementation prevents swine edema disease.

High abundance and diversity of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in faeces and tonsils of pigs at slaughter.

PubMed

Van Damme, I; Garcia-Graells, C; Biasino, W; Gowda, T; Botteldoorn, N; De Zutter, L

2017-09-01

This cross-sectional study investigates the abundance of cefotaxime-resistant Escherichia coli (CREC) in the faeces and tonsils of 96 pigs during slaughter. Moreover, different isolates from a selected number of pigs were tested to study the diversity of bla ESBL genes within E. coli isolates from one pig. Cefotaxime-resistant bacteria (based on enumeration results on MacConkey agar supplemented with 1mg/L cefotaxime) were found in the faeces of 77 pigs (80%; 95% CI: 70-87%) and the tonsils of 91 pigs (95%; 95% CI: 88%-98%). Cefotaxime-resistant E. coli (based on enumeration results on Tryptone Bile X-glucuronide agar supplemented with 1mg/L cefotaxime) were detected in 72 faecal samples (75%; 95% CI: 64-83%) and 45 tonsil samples (47%; 95% CI: 35-59%), in numbers up to 5.5 and 5.6log 10 CFU/g, respectively. On average, around 1/10,000 E. coli in both faeces and tonsils were cefotaxime-resistant, though large variations were observed between pigs. Within one sample, CREC isolates with up to five different combinations of ESBL genes were observed. In three out of 16 faecal samples and six out of 14 tonsil samples, only one ESBL gene profile was found. The high numbers of CREC that are occasionally found in the faeces and tonsils of pigs during slaughter may represent an important source of contamination of carcasses and subsequently pork. Copyright © 2017 Elsevier B.V. All rights reserved.

Mupirocin-mucin agar for selective enumeration of Bifidobacterium bifidum.

PubMed

Pechar, Radko; Rada, Vojtech; Parafati, Lucia; Musilova, Sarka; Bunesova, Vera; Vlkova, Eva; Killer, Jiri; Mrazek, Jakub; Kmet, Vladimir; Svejstil, Roman

2014-11-17

Bifidobacterium bifidum is a bacterial species exclusively found in the human intestinal tract. This species is becoming increasingly popular as a probiotic organism added to lyophilized products. In this study, porcine mucin was used as the sole carbon source for the selective enumeration of B. bifidum in probiotic food additives. Thirty-six bifidobacterial strains were cultivated in broth with mucin. Only 13 strains of B. bifidum utilized the mucin to produce acids. B. bifidum was selectively enumerated in eight probiotic food supplements using agar (MM agar) containing mupirocin (100 mg/L) and mucin (20 g/L) as the sole carbon source. MM agar was fully selective if the B. bifidum species was presented together with Bifidobacterium animalis subsp. lactis, Bifidobacterium breve, and Bifidobacterium longum subsp. longum species and with lactic acid bacteria (lactobacilli, streptococci). Isolated strains of B. bifidum were identified using biochemical, PCR, MALDI-TOF procedures and 16S rRNA gene sequencing. The novel selective medium was also suitable for the isolation of B. bifidum strains from human fecal samples. Copyright © 2014 Elsevier B.V. All rights reserved.

OCCURRENCE OF VANCOMYCIN RESISTANT ENTEROCOCCI IN ANIMAL FECES

EPA Science Inventory

A survey was conducted to determine the occurrence of vancomycin resistant Enterococci (VRE) in animal and human fecal samples. A selective agar mEI, and mEI supplemented with 4 micrograms/ml vancomycin was used in a membrane filtration procedure to determine quantitative levels ...

Fish meal extract bile esculin agar (FMBE) a selective medium for Bacteroides fragilis group.

PubMed

Beena, V K; Rao, S; Kotian, M; Shivananda, P G

1997-07-01

Fish meal extract bile esculin agar (FMBE) is prepared using Fish meal extract concentrate as the basal substance, for the selective isolation and presumptive identification of B.fragilis group. The efficiency of the medium was evaluated by growing stock cultures of B.fragilis groups as well as inoculating clinical specimens and comparing the results with Bacteroides bile esculin agar (BBE). All the 87 stock cultures of B.fragilis grew on FMBE and BBE. No other anaerobes tested grew on the medium. However 7 out of 65 neomycin resistant aerobes grew on the FMBE. From the 100 clinical samples, 62 strains of B. Fragilis group were recovered on FMBE and BBE, and 53 strains on supplemented BHIBA. The cost effectiveness, selectivity and the ability to detect esculin hydrolysis will enable FMBE as a suitable medium as comparable to that of BBE, if not superior.

Development of a More Sensitive and Specific Chromogenic Agar Medium for the Detection of Vibrio parahaemolyticus and Other Vibrio Species.

PubMed

Yeung, Marie; Thorsen, Trevor

2016-11-08

Foodborne infections in the US caused by Vibrio species have shown an upward trend. In the genus Vibrio, V. parahaemolyticus is responsible for the majority of Vibrio-associated infections. Thus, accurate differentiation among Vibrio spp. and detection of V. parahaemolyticus is critically important to ensure the safety of our food supply. Although molecular techniques are increasingly common, culture-depending methods are still routinely done and they are considered standard methods in certain circumstances. Hence, a novel chromogenic agar medium was tested with the goal of providing a better method for isolation and differentiation of clinically relevant Vibrio spp. The protocol compared the sensitivity, specificity and detection limit for the detection of V. parahaemolyticus between the new chromogenic medium and a conventional medium. Various V. parahaemolyticus strains (n=22) representing diverse serotypes and source of origins were used. They were previously identified by Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC), and further verified in our laboratory by tlh-PCR. In at least four separate trials, these strains were inoculated on the chromogenic agar and thiosulfate-citrate-bile salts-sucrose (TCBS) agar, which is the recommended medium for culturing this species, followed by incubation at 35-37 °C for 24-96 hr. Three V. parahaemolyticus strains (13.6%) did not grow optimally on TCBS, nonetheless exhibited green colonies if there was growth. Two strains (9.1%) did not yield the expected cyan colonies on the chromogenic agar. Non-V. parahaemolyticus strains (n=32) were also tested to determine the specificity of the chromogenic agar. Among these strains, 31 did not grow or exhibited other colony morphologies. The mean recovery of V. parahaemolyticus on the chromogenic agar was ~96.4% relative to tryptic soy agar supplemented with 2% NaCl. In conclusion, the new chromogenic agar is an effective medium to detect V. parahaemolyticus and to differentiate it from other vibrios.

Nutrient agar with sodium chloride supplementation for presumptive detection of Moraxella catarrhalis in clinical specimens.

PubMed

Nishiyama, Hiroyuki; Saito, Ryoichi; Chida, Toshio; Sano, Kazumitsu; Tsuchiya, Tatsuyuki; Okamura, Noboru

2012-04-01

We previously reported that Nissui nutrient agar (N medium) promoted the growth of Moraxella catarrhalis but not commensal Neisseria spp. In the present study, we examined which constituent of N medium was responsible for the selective growth of M. catarrhalis using 209 M. catarrhalis and 100 commensal Neisseria spp. clinical strains. We found that peptone, but not meat extract or agar of N medium, had growth-promoting or growth-inhibiting ability with respect to M. catarrhalis and commensal Neisseria spp. Thus, we investigated the amino acid content of N peptone and found it had higher concentrations of amino acids than other commercial peptone products. On varying the sodium chloride concentration of reconstituted N medium, we noted that the concentration was an important factor in bacterial growth differences. Varying the sodium chloride concentration of other commercial nutrient agars achieved similar results to those for N medium. This is, to our knowledge, the first study observing that sodium chloride concentration is responsible for difference in growth between the two organisms. We also successfully isolated colonies of M. catarrhalis from respiratory specimens on N medium, whereas the growth of commensal Neisseria spp. was inhibited, and by adding bovine hematin and β-NAD we were able to isolate Haemophilus influenzae colonies as efficiently as with a chocolate agar. In conclusion, nutrient agar can be used as a medium for the preferential isolation of M. catarrhalis from upper respiratory tract specimens.

Influence of Sodium Chloride on Growth of Neisseria meningitidis

PubMed Central

Mitzel, John R.; Hunter, Jack A.; Beam, Walter E.

1972-01-01

Nasopharyngeal isolates of Neisseria meningitidis were tested for growth on nutrient agar with and without the addition of 0.8% sodium chloride. Of the 822 strains tested, 1.3% grew on the salt-free medium, and 74.1% grew on the medium supplemented with sodium chloride. PMID:4626905

Improving agar electrospinnability with choline-based deep eutectic solvents.

PubMed

Sousa, Ana M M; Souza, Hiléia K S; Uknalis, Joseph; Liu, Shih-Chuan; Gonçalves, Maria P; Liu, LinShu

2015-09-01

Very recently our group has produced novel agar-based fibers by an electrospinning technique using water as solvent and polyvinyl alcohol (PVA) as co-blending polymer. Here, we tested the deep eutectic solvent (DES), (2-hydroxyethyl)trimethylammonium chloride/urea prepared at 1:2 molar ratio, as an alternative solvent medium for agar electrospinning. The electrospun materials were collected with an ethanol bath adapted to a previous electrospinning set-up. One weight percent agar-in-DES showed improved viscoelasticity and hence, spinnability, when compared to 1 wt% agar-in-water and pure agar nanofibers were successfully electrospun if working above the temperature of sol-gel transition (∼80 °C). By changing the solvent medium we decreased the PVA concentration (5 wt% starting solution) and successfully produced composite fibers with high agar contents (50/50 agar/PVA). Best composite fibers were formed with the 50/50 and 30/70 agar/PVA solutions. These fibers were mechanically resistant, showed tailorable surface roughness and diverse size distributions, with most of the diameters falling in the sub-micron range. Both nano and micro forms of agar fibers (used separately or combined) may have potential for the design of new and highly functional agar-based materials. Published by Elsevier B.V.

Influence of composition of diluent on populations of yeasts and moulds recovered from raw fruits.

PubMed

Beuchat, L R; Scouten, A J; Jablonska, J

2002-01-01

The aims of this study were (i) to determine the retention of viability of mycoflora removed from raw fruits, and how this affected diluents used to prepare samples for enumeration of propagules, and (ii) to evaluate the performance of recovery media for supporting colony development. Yeasts and moulds removed from seven types of raw fruit were held in seven diluents for 1 h before plating on dichloran rose bengal chloramphenicol (DRBC) agar and plate count agar supplemented with chloramphenicol (100 micro g ml-1) (PCAC). Significant reductions (P=0.05) in populations of yeasts, moulds, and yeasts plus moulds occurred within the 1 h holding period, regardless of diluent composition. Overall, retention of viability was not influenced by diluent composition, and neither DRBC agar nor PCAC were superior in supporting colony development. The composition of diluents used to prepare food samples for mycological analysis has little affect on the number of yeasts and moulds recovered from seven types of naturally contaminated raw fruit. Both DRBC agar and PCAC are suitable as enumeration media. Diluents and media most often recommended for enumerating yeasts and moulds in foods are appropriate for raw fruits.

Helicobacter pylori: prevalence and antibiotic susceptibility among Kenyans.

PubMed

Kimang'a, Andrew Nyerere; Revathi, Gunturu; Kariuki, Samuel; Sayed, Shahin; Devani, Smita

2010-01-01

Helicobacter pylori infection in Kenya is staggeringly high. Evidence links infection of the gastric mucosa by H. pylori with subsequent development of gastric pathologies. We investigated the prevalence of H. pylori in dyspeptic patients, its relationship with gastric pathologies, and associated antibiotic susceptibility profiles, and compared two media to find the appropriate medium that enhances growth and expedites culture and isolation. Rapid urease and histological tests were used to screen for H. pylori. Culture was performed to test sensitivity and evaluate media. Selective and nutritional supplements were added to culture media (Colombia blood agar and brain-heart infusion agar) for growth enhancement. E-test strips for metronidazole, amoxicillin and clarithromycin were used for susceptibility testing. The prevalence of H. pylori infection in children was 73.3%, and 54.8% in adults. All the H. pylori investigated in this study were largely sensitive to clarithromycin (100%, minimum inhibiting concentration (MIC) <2 microg/ml), amoxicillin (100%, MIC <2 microg/ml) and metronidazole (95.4%, MIC <8 microg/ml). There was, however, occasional resistance to metronidazole (4.6%, MIC >8 microg/ml). Both Colombia blood and brain-heart infusion agar, with the supplements, effectively supported H. pylori growth. Growth was achieved in an average of 36 hours for primary isolations and 24 hours for subcultures. The media described here reduce the time required to culture and isolate bacteria and perform susceptibility testing. Despite the high prevalence of H. pylori infection, the associated pathology is low and does not parallel H. pylori prevalence in the population.

Use of Dehydrated Agar to Estimate Microbial Water Quality for Horticulture Irrigation.

PubMed

Meador, Dustin P; Fisher, Paul R; Guy, Charles L; Harmon, Philip F; Peres, Natalia A; Teplitski, Max

2016-07-01

Petrifilms are dehydrated agar culture plates that have been used to quantify colony forming units (CFU) mL of either aerobic bacteria (Petrifilm-AC) or fungus (Petrifilm-YM), depending on substrate composition. Microbes in irrigation systems can indicate biofilm risk and potential clogging of irrigation emitters. The research objective was to compare counts on Petrifilms versus traditional, hydrated-agar plates using samples collected from recirculated irrigation waters and cultures of isolated known species. The estimated count (in CFU mL) from a recirculated irrigation sample after 7 d of incubation on Petrifilm-YM was only 5.5% of the count quantified using sabouraud dextrose agar (SDA) with chloramphenicol after 14 d. In a separate experiment with a known species, Petrifilm-YM did not successfully culture zoospores of . Isolates of viable zoospores were cultured successfully on potato-dextrose agar (PDA), with comparable counts with a vegetable juice medium supplemented with the antibiotics pimaricin, ampicillin, rifamycin, pentochloronitrobenzene and hymexazol (PARP-H). The quantification of pv. Begoniaceae on Petrifilm-AC was not significantly different ( < 0.05) than on PDA, but was lower than on Reasoner and Goldrich agar (R2A) or with a hemocytometer. The current formulation of Petrifilm-YM is unlikely to be a useful monitoring method for plant pathogens in irrigation water because of the inability to successfully culture oomycetes. However, Petrifilm-AC was an effective method to quantify bacteria and can provide an easy-to-use on-farm tool to monitor biofilm risk and microbial density. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

[Evaluation of a new medium, eggplant (Solanum melongena) agar as a screening medium for Cryptococcus neoformans in environmental samples].

PubMed

Sengul, Mustafa; Ergin, Cağrı; Kartal, Tuğba

2014-04-01

Cryptococcus neofomans is an encapsulated yeast-like fungus that causes life-threatening infections, especially in immunosuppresive patients. C.neoformans infection is believed to be acquired via inhalation of aerosolized particles from the environment. Avian guano, decaying tree hollows and soil are the related known environmental niches. Brown pigmented yeast growth from the precursors in growth media is an important step for the identification and isolation of C.neoformans. Seeds of plants in nature are preferred owing to easy accessibility and low costs for the preparation of such media. Guizotia abysinicca (Niger seed) as Staib agar, Helianthus annus (Sunflower) as Pal's medium, Brassica nigra (Mustard) agar, tobacco agar, Mucuna pruriens (Velvet bean) seed agar, Perilla frutescens (Beefsteak plant) seed agar, Rubus fruticosus (Blackberry) agar and ground red hot pepper agar are pigment-based selective media for the differentiation of C.neoformans. The aim of this study was to observe the pigment production of C.neoformans in a new medium based on eggplant (Solanum melongena) and also to compare its performance with the simplified Staib, Pal's and tobacco agar for isolation from the environment. Three different eggplant-based medium (S.melongena Melanzaza viserba, S.melongena Pinstripe F1 and S.ovigerum Ivory F1) were included in the study. Pigment-forming eggplant medium, simplified Staib agar, Pal's agar and tobacco agar were used for the cultivation of the environmental swabbed samples from 19 Eucalyptus camaldulensis trunk hollows in continuous colonization region. While pigment formation were observed with S.melongena Melanzaza viserba and S.melongena Pinstripe F1 containing media, S.ovigerum Ivory F1 medium was found to be non-reactive. In colonization area (Gökova-Akyaka, Turkey), 11 (57.9%) out of 19 E.camaldulensis samples were positive with simplified Staib agar, Pal's agar and eggplant agar while 10 (52.6%) of them are positive with tobacco agar. C.neoformans colony forming unit (cfu) per plate were found as 51, 57 and 48 (median values) on simplified Staib agar, Pal's agar and eggplant agar, respectively, while tobacco agar has lower performance with 33 cfu/petri. No statistically significant difference were found between simplified Staib agar, Pal's agar and eggplant agar's performances for C.neoformans isolations from the nature (p=0.71). In conclusion, easily prepared eggplant agar is as functional as widely used media such as simplified Staib agar and Pal's agar for the isolation of C.neoformans from the natural environment.

Promotion of chlamydoconidium formation in Candida albicans by corn meal broth incubation.

PubMed

Nakamoto, S

1998-04-01

Chlamydoconidium formation can be used as a tool for the identification of Candida albicans. While chlamydoconidia are known to be inducible on corn meal agar, this report demonstrates that testing in liquid media supplemented with milk or serum enhances chlamydoconidium formation and the formation of complex mycelial clusters.

Three Strains of Pseudomonas fluorescens Exhibit Differential Toxicity Against Drosophila melanogaster

USDA-ARS?s Scientific Manuscript database

Three strains of Pseudomonas fluorescens were tested for toxicity to Drosophila melanogaster in an insect feeding assay. Insect eggs were placed on the surface of a non-nutritive agar plate supplemented with a food source that was non-inoculated or inoculated with P. fluorescens Pf0-1, SBW25, or Pf-...

Improvement of Polymyxin-Egg Yolk-Mannitol-Bromothymol Blue Agar for the Enumeration and Isolation of Bacillus cereus in Various Foods.

PubMed

Kang, Il-Byeong; Chon, Jung-Whan; Kim, Dong-Hyeon; Jeong, Dana; Kim, Hong-Seok; Kim, Hyunsook; Seo, Kun-Ho

2017-03-01

A modified polymyxin-egg yolk-mannitol-bromothymol blue agar (mPEMBA) was developed by supplementing polymyxin-egg yolk-mannitol-bromothymol blue agar (PEMBA) with trimethoprim to improve the selectivity for and recoverability of Bacillus cereus from naturally and artificially contaminated food samples. The number of B. cereus in mPEMBA was significantly higher than in PEMBA, indicating better recoverability (P < 0.05) in red pepper powder (PEMBA 0.80 ± 0.22 log CFU/g versus mPEMBA 1.95 ± 0.17 log CFU/g) and soybean paste (PEMBA 2.19 ± 0.18 log CFU/g versus mPEMBA 3.09 ± 0.13 log CFU/g). In addition, mPEMBA provided better visual differentiation of B. cereus colonies than PEMBA, which is attributable to the reduced number of competing microflora. We conclude that the addition of trimethoprim to PEMBA could generate a synergistic effect to improve selectivity for B. cereus .

Extraction of agar from Gelidium sesquipedale (Rhodopyta) and surface characterization of agar based films.

PubMed

Guerrero, P; Etxabide, A; Leceta, I; Peñalba, M; de la Caba, K

2014-01-01

The chemical structure of the agar obtained from Gelidium sesquipedale (Rhodophyta) has been determined by (13)C nuclear magnetic resonance ((13)C NMR) and Fourier transform infrared spectroscopy (FTIR). Agar (AG) films with different amounts of soy protein isolate (SPI) were prepared using a thermo-moulding method, and transparent and hydrophobic films were obtained and characterized. FTIR analysis provided a detailed description of the binding groups present in the films, such as carboxylic, hydroxyl and sulfonate groups, while the surface composition was examined using X-ray photoelectron spectroscopy (XPS). The changes observed by FTIR and XPS spectra suggested interactions between functional groups of agar and SPI. This is a novel approach to the characterization of agar-based films and provides knowledge about the compatibility of agar and soy protein for further investigation of the functional properties of biodegradable films based on these biopolymers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Influence of culture media and environmental factors on mycelial growth and sporulation of Lasiodiplodia theobromae (Pat.) Griffon and Maubl.

PubMed

Saha, A; Mandal, P; Dasgupta, S; Saha, D

2008-05-01

Lasiodiplodia theobromae, a common tea (Camellia sinensis) pathogen, usually does not sporulate or sporulates poorly in common media, which makes spore production difficult. In this study the effects of culture media, carbon source, nitrogen source, temperature, pH and light on mycelial growth and sporulation were evaluated. Among several carbon sources tested, glucose and sucrose were found superior for growth. Potassium nitrate supplemented media showed maximum growth amongst the tested inorganic nitrogen sources while peptone produced maximum growth among the tested organic nitrogen sources. Tea root extract supplemented potato dextrose agar medium was found to be the most suitable for mycelial growth and sporulation of L. theobromae. The fungus grow at temperatures ranging from 40 to 36 degrees C, with optimum growth at 28 degrees C and no growth was noted at 40 degrees C. There was no significant effect of different light period on growth of L. theobromae, but light enhanced sporulation. The fungus grow at pH 3.0-8.0 and optimum growth was observed at pH 6.0. Tea root extract supplemented potato dextrose agar medium with pH 6.0 was the most suitable for production of conidia of L. theobromae at 28 degrees C. Hence this media may be recommended for inoculum production for further studies.

Improvement of mannitol-yolk-polymyxin B agar by supplementing with trimethoprim for quantitative detection of Bacillus cereus in foods.

PubMed

Chon, Jung-Whan; Hyeon, Ji-Yeon; Park, Jun-Ho; Song, Kwang-Young; Kim, Jong-Hyun; Seo, Kun-Ho

2012-07-01

Mannitol-yolk-polymyxin B agar (MYPA) was modified by supplementation with trimethoprim. The ability of the supplemented medium to select for and recover Bacillus cereus from pure cultures and food samples with high background microflora was compared with MYPA. For evaluation of the modified MYPA (mMYPA) in food samples with high background microflora, B. cereus was experimentally spiked into red pepper powder, fermented soybean paste, vegetable salad, and radish sprouts, and then it was recovered on MYPA and mMYPA for comparison. In all food samples, there was no difference in recoverability (P > 0.05) between mMYPA (red pepper powder, 3.34 ± 0.24 log CFU/g; fermented soybean paste, 3.52 ± 0.47 log CFU/g; vegetable salad, 3.51 ± 0.23 log CFU/g; radish sprouts, 3.32 ± 0.40 log CFU/g) and MYPA (red pepper powder, 3.18 ± 0.20 log CFU/g; fermented soybean paste, 3.33 ± 0.43 log CFU/g; vegetable salad, 3.36 ± 0.19 log CFU/g; radish sprouts, 3.33 ± 0.31 log CFU/g). However, mMYPA exhibited better selectivity than MYPA, because additional trimethoprim made the differentiation of suspected colonies easier by inhibiting competing flora. The addition of trimethoprim to conventional media could be a useful option to improve selectivity in foods with high background microflora.

Isolation of Shiga toxin-producing Escherichia coli serogroups O26, O45, O103, O111, O121, and O145 from ground beef using modified rainbow agar and post-immunomagnetic separation acid treatment.

PubMed

Tillman, Glenn E; Wasilenko, Jamie L; Simmons, Mustafa; Lauze, Todd A; Minicozzi, Joseph; Oakley, Brian B; Narang, Neelam; Fratamico, Pina; Cray, Ailliam C

2012-09-01

It is estimated that at least 70% of human illnesses due to non-O157 Shiga toxin-producing Escherichia coli (STEC) in the United States are caused by strains from the top six serogroups (O26, O45, O103, O111, O121, and O145). Procedures for isolating STEC from food products often use plating media that include antimicrobial supplements at concentrations that inhibit background microflora growth but can also inhibit target STEC growth. In this study, an agar medium with lower supplement concentrations, modified Rainbow agar (mRBA), was evaluated for recovery of STEC serogroups O26, O45, O103, O111, O121, and O145 from ground beef enrichments. A post-immunomagnetic separation (IMS) acid treatment step was additionally used to reduce background microflora and increase recovery of target STEC strains. Ground beef samples (325 g) were artificially contaminated with STEC and confounding organisms and enriched for 15 h. Recovery of the target STEC was attempted on the enrichments using IMS and plating onto mRBA and Rainbow agar (RBA). Additionally, acid treatment was performed on the post-IMS eluate followed by plating onto mRBA. Using the combination of mRBA and acid treatment, target STEC were isolated from 103 (85.8%) of 120 of the low-inoculated samples (1 to 5 CFU/325-g sample) compared with 68 (56.7%) of 120 using no acid treatment and plating onto RBA with higher levels of novobiocin and potassium tellurite. The combination of acid treatment and mRBA provides a significant improvement over the use of RBA for isolation of STEC serogroups O26, O45, O103, O111, O121, and O145 from raw ground beef.

A novel plant-based-sea water culture media for in vitro cultivation and in situ recovery of the halophyte microbiome.

PubMed

Saleh, Mohamed Y; Sarhan, Mohamed S; Mourad, Elhussein F; Hamza, Mervat A; Abbas, Mohamed T; Othman, Amal A; Youssef, Hanan H; Morsi, Ahmed T; Youssef, Gehan H; El-Tahan, Mahmoud; Amer, Wafaa A; Fayez, Mohamed; Ruppel, Silke; Hegazi, Nabil A

2017-11-01

The plant-based-sea water culture medium is introduced to in vitro cultivation and in situ recovery of the microbiome of halophytes. The ice plant ( Mesembryanthemum crystallinum ) was used, in the form of juice and/or dehydrated plant powder packed in teabags, to supplement the natural sea water. The resulting culture medium enjoys the combinations of plant materials as rich source of nutrients and sea water exercising the required salt stress. As such without any supplements, the culture medium was sufficient and efficient to support very good in vitro growth of halotolerant bacteria. It was also capable to recover their in situ culturable populations in the phyllosphere, ecto-rhizosphere and endo-rhizosphere of halophytes prevailing in Lake Mariout, Egypt. When related to the total bacterial numbers measured for Suaeda pruinosa roots by quantitative-PCR, the proposed culture medium increased culturability (15.3-19.5%) compared to the conventional chemically-synthetic culture medium supplemented with (11.2%) or without (3.8%) NaCl. Based on 16S rRNA gene sequencing, representative isolates of halotolerant bacteria prevailed on such culture medium were closely related to Bacillus spp., Halomonas spp., and Kocuria spp. Seed germination tests on 25-50% sea water agar indicated positive interaction of such bacterial isolates with the germination and seedlings' growth of barley seeds.

Production of Antilisterial Bacteriocins from Lactic Acid Bacteria in Dairy-Based Media: A Comparative Study.

PubMed

Ünlü, Gülhan; Nielsen, Barbara; Ionita, Claudia

2015-12-01

One hundred and eight strains of lactic acid bacteria (LAB) were screened for bacteriocin production by the modified deferred antagonism and agar well diffusion methods. When the modified deferred antagonism method was employed, 82 LAB strains showed inhibitory action against Listeria monocytogenes v7 ½a, whereas 26 LAB strains expressed no inhibition. Only 12 LAB strains exhibited inhibitory activity when the agar well diffusion method was used, 11 of which had been previously recognized as bacteriocin production positive (Bac(+)). Lactobacillus viridescens NRRL B-1951 was determined, for the first time, to produce an inhibitory compound with a proteinaceous nature. The inhibitory activity was observed in the presence of lipase, α-chymotrypsin, and trypsin, but no inhibition zone could be detected in the presence of proteinase K, indicating the proteinaceous nature of the inhibitory compound. The inhibitory compound was active against Lact. sake ATCC 15521 and Lact. plantarum NCDO 995. Bacteriocin production by the Bac(+) LAB strains was assessed in Lactobacillus MRS Broth as well as in dairy-based media such as nonfat milk, demineralized whey powder, and cheddar cheese whey supplemented with complex nutrient sources that are rich in nitrogen. Lact. sake ATCC 15521 and L. monocytogenes CWD 1002, CWD 1092, CWD 1157, CWD 1198, and v7 ½a were used as indicators. The inhibitory activities of the bacteriocins varied depending on the indicator strains and the growth media used. The LAB indicator strains were found to be more sensitive to inhibition by bacteriocins when compared to the listerial indicator strains. Among the listerial indicators, L. monocytogenes CWD 1002 and CWD 1198 were the most sensitive strains to the bacteriocins investigated in this study. Media composition had a significant influence on bacteriocin production and activity. When compared to demineralized whey powder medium and cheddar cheese whey medium supplemented with whey protein concentrate, cheddar cheese whey medium supplemented with complex nutrient sources such as yeast extract, polypeptone, proteose peptone nr. 3, or soytone appeared to be more supportive of bacteriocin production.

Influence of ethylenediamine-n,n’-disuccinic acid (EDDS) concentration on the bactericidal activity of fatty acids in vitro

USDA-ARS?s Scientific Manuscript database

The antibacterial activity of mixtures of ethylenediamine-N,N’-disuccinic acid (EDDS) and antibacterial fatty acids (FA) was examined using the agar diffusion assay. Solutions of caproic, caprylic, capric, and lauric acids dissolved in potassium hydroxide (KOH) were supplemented with 0, 5, or 10 mM ...

Characterization of nitrate-reducing and amino acid-using bacteria prominent in nitrotoxin-enriched equine cecal populations

USDA-ARS?s Scientific Manuscript database

In the present study, populations of equine cecal microbes enriched for enhanced rates of 3-nitro-1-propionic acid (NPA) or nitrate metabolism were diluted and cultured for NPA-metabolizing bacteria on a basal enrichment medium (BEM) or tryptose soy agar (TSA) medium supplemented with either 5 mM NP...

Characterization of Tolypocladium cylindrosporum (Hypocreales: Ophiocordycipitacea) and its impact against Aedes aegypti and Aedes albopictus eggs at low temperature

USDA-ARS?s Scientific Manuscript database

We examined the growth characteristics of Tolypocladium cylindrosporum IBT 41712 and its potential to infect eggs of Aedes aegypti Linnaeus and Aedes albopictus (Skuse) mosquitoes at low temperature (15 deg C). When grown on sabouraud dextrose agar supplemented with yeast extract, IBT 41712 formed w...

Isolation and Purification of Antibiotic Material from Physarum gyrosum

PubMed Central

Schroeder, H. R.; Mallette, M. F.

1973-01-01

The myxomycete Physarum gyrosum was cultured in its plasmodial stage on agar plates containing 0.025 M phosphate buffer at pH 6.5, 2% bakers' yeast, and 0.2% glucose and was supplemented with live Escherichia coli. Extracts of these plasmodia contained several antibiotic substances. Antibiotic materials were partially purified by dialysis of the agar medium-mold mixture, evaporation of the dialyzate, and butanol extraction of the residue. Further purification in two paper and two thin-layer chromatographic systems gave one product which was pure in six thin-layer chromatographic systems. Antibiotic activity against some gram-positive and gram-negative bacteria and yeasts was demonstrated with partially purified extracts and a paper-chromatographically separated fraction. One pure antibiotic was effective against Bacillus cereus. PMID:4799591

Proposed quality control guidelines for antimicrobial susceptibility tests using tilmicosin.

PubMed Central

Shryock, T R; White, D W; Werner, C S; Staples, J M

1995-01-01

Quality control guidelines for tilmicosin, a novel veterinary-use-only macrolide, were developed in a multi-laboratory study according to established National Committee for Clinical Laboratory Standards (NCCLS) procedures (M23-T2). Tilmicosin was incorporated into Sensititre plates for broth microdilution endpoint testing and into two lots of 15-micrograms disks for Kirby-Bauer agar disk diffusion testing. One common lot and five unique lots of Mueller-Hinton media were used. (Broth was cation adjusted, and agar was supplemented with 5% defibrinated sheep blood.) Bacteria used for reference strains included Pasteurella haemolytica 128K, Pasteurella multocida ATCC 43137, and Staphylococcus aureus ATCC 29213 (microdilution) and ATCC 25923 (disk). Replicate tests were conducted. Disk diffusion and broth microdilution quality control ranges are proposed. PMID:7714188

Evaluation of potassium-clavulanate-supplemented modified charcoal-cefoperazone-deoxycholate agar for enumeration of Campylobacter in chicken carcass rinse.

PubMed

Chon, Jung-Whan; Kim, Hong-Seok; Kim, Hyunsook; Oh, Deog-Hwan; Seo, Kun-Ho

2014-05-01

Potassium-clavulanate-supplemented modified charcoal-cefoperazone-deoxycholate agar (C-mCCDA) that was described in our previous study was compared with original mCCDA for the enumeration of Campylobacter in pure culture and chicken carcass rinse. The quantitative detection of viable Campylobacter cells from a pure culture, plated on C-mCCDA, is statistically similar (P > 0.05) to mCCDA. In total, 120 chickens were rinsed using 400 mL buffered peptone water. The rinses were inoculated onto C-mCCDA and mCCDA followed by incubation at 42 °C for 48 h. There was no statistical difference between C-mCCDA (45 of 120 plates; mean count, 145.5 CFU/mL) and normal mCCDA (46 of 120 plates; mean count, 160.8 CFU/mL) in the isolation rate and recovery of Campylobacter (P > 0.05) from chicken carcass rinse. The Pearson correlation coefficient value for the number of Campylobacter cells recovered in the 2 media was 0.942. However, the selectivity was much better on C-mCCDA than on mCCDA plates (P < 0.05). Significantly fewer C-mCCDA plates (33 out of 120 plates; mean count, 1.9 CFU/mL) were contaminated with non-Campylobacter cells than the normal mCCDA plates (67 out of 120 plates; mean count, 27.1 CFU/mL). The C-mCCDA may provide improved results for enumeration of Campylobacter in chicken meat alternative to mCCDA with its increased selectivity the modified agar possess. © 2014 Institute of Food Technologists®

Effects of Gelling Agent and Extracellular Signaling Molecules on the Culturability of Marine Bacteria

PubMed Central

Rygaard, Anita Mac; Thøgersen, Mariane Schmidt; Nielsen, Kristian Fog; Gram, Lone

2017-01-01

ABSTRACT Only 1% of marine bacteria are currently culturable using standard laboratory procedures, and this is a major obstacle for our understanding of the biology of marine microorganisms and for the discovery of novel microbial natural products. Therefore, the purpose of this study was to investigate if improved cultivation conditions, including the use of an alternative gelling agent and supplementation with signaling molecules, improve the culturability of bacteria from seawater. Replacing agar with gellan gum improved viable counts 3- to 40-fold, depending on medium composition and incubation conditions, with a maximum of 6.6% culturability relative to direct cell counts. Through V4 amplicon sequencing we found that culturable diversity was also affected by a change in gelling agent, facilitating the growth of orders not culturable on agar-based substrates. Community analyses showed that communities grown on gellan gum substrates were significantly different from communities grown on agar and that they covered a larger fraction of the seawater community. Other factors, such as incubation temperature and time, had less obvious effects on viable counts and culturable diversity. Supplementation with acylated homoserine lactones (AHLs) did not have a positive effect on total viable counts or a strong effect on culturable diversity. However, low concentrations of AHLs increased the relative abundance of sphingobacteria. Hence, with alternative growth substrates, it is possible to significantly increase the number and diversity of cultured marine bacteria. IMPORTANCE Serious challenges to human health, such as the occurrence and spread of antibiotic resistance and an aging human population in need of bioactive pharmaceuticals, have revitalized the search for natural microbial products. The marine environment, representing the largest ecosystem in the biosphere, harbors an immense and virtually untapped microbial diversity producing unique bioactive compounds. However, we are currently able to cultivate only a minute fraction of this diversity. The lack of cultivated microbes is hampering not only bioprospecting efforts but also our general understanding of marine microbes. In this study, we present a means to increase the number and diversity of cultured bacteria from seawater, showing that relatively simple changes to medium components may facilitate the isolation and growth of hitherto unknown bacterial orders. PMID:28213548

Characteristics of thermoplastic sugar palm Starch/Agar blend: Thermal, tensile, and physical properties.

PubMed

Jumaidin, R; Sapuan, S M; Jawaid, M; Ishak, M R; Sahari, J

2016-08-01

The aim of this work is to study the behavior of biodegradable sugar palm starch (SPS) based thermoplastic containing agar in the range of 10-40wt%. The thermoplastics were melt-mixed and then hot pressed at 140°C for 10min. SEM investigation showed good miscibility between SPS and agar. FT-IR analysis confirmed that SPS and agar were compatible and inter-molecular hydrogen bonds existed between them. Incorporation of agar increased the thermoplastic starch tensile properties (Young's modulus and tensile strength). The thermal stability and moisture uptake increased with increasing agar content. The present work shows that starch-based thermoplastics with 30wt% agar content have the highest tensile strength. Higher content of agar (40wt%) resulted to more rough cleavage fracture and slight decrease in the tensile strength. In conclusion, the addition of agar improved the thermal and tensile properties of thermoplastic SPS which widened the potential application of this eco-friendly material. The most promising applications for this eco-friendly material are short-life products such as packaging, container, tray, etc. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative study on the microbiological features of angular cheilitis in HIV seropositive and HIV seronegative patients from South India

PubMed Central

Krishnan, P Anitha; Kannan, Ranganathan

2013-01-01

Objective: This study was designed to compare the microbiological features of angular cheilitis (AC) in human immunodeficiency virus (HIV) seropositive and HIV seronegative individuals, in a group of south Indians. Materials and Methods: Swabs from oral commissures of 46 patients were obtained and inoculated on to Sabouraud's dextrose agar (SDA) supplemented with chloramphenicol, blood agar (BA) and MacConkey's agar (MCA) plates and cultured. α-hemolytic Streptococci, Staphylococcus albus, Staphylococcus aureus, Candida species, Klebsiella species and Pseudomonas species were cultured. Candidal colonies were further speciated by the conventional biotyping technique. Results: In AC of HIV seropositive patients Candida albicans and Staphylococcus aureus were more prevalent than that in HIV seronegative patients. Incidentally in patients with CD4 cell count less than 200 there was an increase in the incidence of Candidal and Staphylococcus aureus colonization when compared to patients with CD4 cell count higher than 200. Conclusion: The present study suggests a definite difference in the microbial flora of AC in HIV seropositive patients than that of HIV seronegative population. PMID:24574650

Establishing axenic cultures from mature pecan embryo explants on media with low water availability.

PubMed

Obeidy, A A; Smith, M A

1990-12-01

Endophytic fungi associated with mature pecan (Carya illinoensis (Wangenh.) C. Koch) nuts prevented successful, contaminant-free in vitro culture of embryo expiants, even after rigorous surface disinfestation of the nuts and careful aseptic shelling. Disinfestation with sodium hypochlorite after shell removal was also unsuccessful, because even dilute concentrations which were ineffective against the fungal contaminants prevented subsequent growth from the embryo. Explanting media with low water availability which would not sustain growth of fungal contaminants, but supported growth from mature pecan embryos, were developed as an alternative disinfestation method. The explanting media were supplemented with 0.9-1.5% agar, and other media components were selectively omitted to test their influence on water availability and fungal growth. Disinfestation of up to 65% of the cultures was accomplished, depending on the medium formulation, compared to 100% loss to contamination on control medium (0.5% agar). A complete medium (containing sucrose, salts, vitamins, 18 μM BAP, and 5 μM IBA) with 1.5% agar provided control of contamination, and encouraged subsequent regeneration from the embryo expiants, which remained free of contaminant growth through subsequent subcultures.

A study of electrochemical devices based on Agar-Agar-NH4I biopolymer electrolytes

NASA Astrophysics Data System (ADS)

Selvalakshmi, S.; Mathavan, T.; Selvasekarapandian, S.; Premalatha, M.

2018-04-01

A polymer electrolyte system has been developed using a biopolymer namely, Agar-Agar in combination with ammonium iodide in different weight percentages by solution casting technique. The films were characterized electrically by AC Impedance Spectroscopy for its conductivity. The highest conductivity achieved at room temperature was for 50 wt. % agar-agar: 50 wt. % NH4I with a conductivity value of 1.20 × 10-4 Scm-1. An electrochemical cell was fabricated in the configuration of: Zn + ZnSO4.7H2O + graphite (anode) | 50 wt. % (Agar-agar): 50 wt. % NH4I (electrolyte) | PbO2 + V2O5 + graphite (cathode) and it produced a maximum open circuit voltage of 1.73 V. A single PEM fuel cell was constructed with the highest conducting sample (50 wt. % (Agar-agar): 50 wt. % NH4I) and it exhibited an output voltage of 408mV.

Reduced salivary flow and colonization by mutans streptococci in children with Down syndrome

PubMed Central

Areias, Cristina; Sampaio-Maia, Benedita; de Lurdes Pereira, Maria; Azevedo, Álvaro; Melo, Paulo; Andrade, Casimiro; Scully, Crispian

2012-01-01

OBJECTIVES: Although individuals with Down syndrome have considerable oral disease, the prevalence of dental caries in this group is low. The present study aimed to compare known risk factors for dental caries development in children with Down syndrome and a matched population (siblings). In both populations, the number of acidogenic microorganisms, such as mutans streptococci, lactobacilli and Candida species, and the paraffin-stimulated pH, flow rate and IgA concentration in whole saliva were evaluated and compared. METHOD: Saliva was collected, and the caries index was evaluated in 45 sibling pairs aged between 6 and 18 years old. The salivary IgA concentration was determined by immunoturbidimetry. Salivary mutans streptococci, lactobacilli and Candida species were quantified on mitis salivarius agar containing bacitracin and 20% sucrose, rogosa agar supplemented with glacial acetic acid and sabouraud agar supplemented with chloramphenicol, respectively. RESULTS: Down syndrome children had a higher caries-free rate (p<0.05) and lower salivary mutans streptococci counts (p<0.03) compared to their siblings. Similar numbers of lactobacilli and Candida species were found in both groups. Salivary flow rates were 36% lower in Down syndrome children compared to their siblings (p<0.05). The salivary pH did not differ between Down syndrome children and controls. The Down syndrome children had an IgA secretion rate 29% lower than that of their siblings, but this difference was not statistically significant. CONCLUSIONS: In conclusion, the lower number of mutans streptococci in the saliva may be one of the factors contributing to the lower caries rate observed in Down syndrome children, despite evidence of hyposalivation. PMID:23018295

Formulation and Evaluation of Tramadol hydrochloride Rectal Suppositories.

PubMed

Saleem, M A; Taher, M; Sanaullah, S; Najmuddin, M; Ali, Javed; Humaira, S; Roshan, S

2008-09-01

Rectal suppositories of tramadol hydrochloride were prepared using different bases and polymers like PEG, cocoa butter, agar and the effect of different additives on in vitro release of tramadol hydrochloride was studied. The agar-based suppositories were non-disintegrating/non-dissolving, whereas PEGs were disintegrating/dissolving and cocoa butter were melting suppositories. All the prepared suppositories were evaluated for various physical parameters like weight variation, drug content and hardness. The PEG and cocoa butter suppositories were evaluated for macromelting range, disintegration and liquefaction time. In vitro release study was performed by USP type I apparatus. The prepared suppositories were within the permissible range of all physical parameters. In vitro drug release was in the order of PEG>Agar>cocoa butter. Addition of PVP, HPMC in agar suppositories retards the release. The mechanism of drug release was diffusion controlled and follows first order kinetics. The results suggested that blends of PEG of low molecular weight (1000) with high molecular weight (4000 and 6000) in different percentage and agar in 10% w/w as base used to formulate rapid release suppositories. The sustained release suppositories can be prepared by addition of PVP, HPMC in agar-based suppositories and by use of cocoa butter as base.

The Effects of EDTA (Ethylenediaminetetraacetic Acid) and Sonication on the Disaggregation of Oral Bacteria,

DTIC Science & Technology

1984-01-01

Virginia) and 0.5 g/ml menadione . The plates were c,,ltured for 72 hours anaerobically (<-140 my) at 37C A . and the number of colony forming units (CFU) per...CONTROL Immol lommol lOOmmol L DISPERSED pVVORTEX ~Thuwuuuuiii~FOR 30 SECONDS4 1 4 4 * MENADIONE SUPPLEMENTED SHAEDLER BLOOD AGAR PLATES lw- 2.50 U2.45

In Situ Generation of Oxygen By Electrolysis and the Electrochemical Effects on Microorganisms’ Population

DTIC Science & Technology

1992-06-01

based on availability. Actinomyces can be grown on various media such as starch- casein or a relatively new, commercially available Actinomyces ...Isolation Agar. Actinomyces Isolation Agar was used in this study. Soil samples were obtained by taking cores (using pipettes with the tips removed...bacteria 0.01X Nutrient Agar 10-1 to 10- 21 days Filamentous fungi Sabouraud Maltose Agar 10"° to 10.3 3 days Actinomyces Actinomyces Isolat. Agar 101

Plant-based culture media: Efficiently support culturing rhizobacteria and correctly mirror their in-situ diversity.

PubMed

Youssef, Hanan H; Hamza, Mervat A; Fayez, Mohamed; Mourad, Elhussein F; Saleh, Mohamed Y; Sarhan, Mohamed S; Suker, Ragab M; Eltahlawy, Asmaa A; Nemr, Rahma A; El-Tahan, Mahmod; Ruppel, Silke; Hegazi, Nabil A

2016-03-01

Our previous publications and the data presented here provide evidences on the ability of plant-based culture media to optimize the cultivability of rhizobacteria and to support their recovery from plant-soil environments. Compared to the tested chemically-synthetic culture media (e.g. nutrient agar and N-deficient combined-carbon sources media), slurry homogenates, crude saps, juices and powders of cactus (Opuntia ficus-indica) and succulent plants (Aloe vera and Aloe arborescens) were rich enough to support growth of rhizobacteria. Representative isolates of Enterobacter spp., Klebsiella spp., Bacillus spp. and Azospirillum spp. exhibited good growth on agar plates of such plant-based culture media. Cell growth and biomass production in liquid batch cultures were comparable to those reported with the synthetic culture media. In addition, the tested plant-based culture media efficiently recovered populations of rhizobacteria associated to plant roots. Culturable populations of >10(6)-10(8) cfu g(-1) were recovered from the ecto- and endo-rhizospheres of tested host plants. More than 100 endophytic culture-dependent isolates were secured and subjected to morphophysiological identification. Factor and cluster analyses indicated the unique community structure, on species, genera, class and phyla levels, of the culturable population recovered with plant-based culture media, being distinct from that obtained with the chemically-synthetic culture media. Proteobacteria were the dominant (78.8%) on plant-based agar culture medium compared to only 31% on nutrient agar, while Firmicutes prevailed on nutrient agar (69%) compared to the plant-based agar culture media (18.2%). Bacteroidetes, represented by Chryseobacterium indologenes, was only reported (3%) among the culturable rhizobacteria community of the plant-based agar culture medium.

Plant-based culture media: Efficiently support culturing rhizobacteria and correctly mirror their in-situ diversity

PubMed Central

Youssef, Hanan H.; Hamza, Mervat A.; Fayez, Mohamed; Mourad, Elhussein F.; Saleh, Mohamed Y.; Sarhan, Mohamed S.; Suker, Ragab M.; Eltahlawy, Asmaa A.; Nemr, Rahma A.; El-Tahan, Mahmod; Ruppel, Silke; Hegazi, Nabil A.

2015-01-01

Our previous publications and the data presented here provide evidences on the ability of plant-based culture media to optimize the cultivability of rhizobacteria and to support their recovery from plant-soil environments. Compared to the tested chemically-synthetic culture media (e.g. nutrient agar and N-deficient combined-carbon sources media), slurry homogenates, crude saps, juices and powders of cactus (Opuntia ficus-indica) and succulent plants (Aloe vera and Aloe arborescens) were rich enough to support growth of rhizobacteria. Representative isolates of Enterobacter spp., Klebsiella spp., Bacillus spp. and Azospirillum spp. exhibited good growth on agar plates of such plant-based culture media. Cell growth and biomass production in liquid batch cultures were comparable to those reported with the synthetic culture media. In addition, the tested plant-based culture media efficiently recovered populations of rhizobacteria associated to plant roots. Culturable populations of >106–108 cfu g−1 were recovered from the ecto- and endo-rhizospheres of tested host plants. More than 100 endophytic culture-dependent isolates were secured and subjected to morphophysiological identification. Factor and cluster analyses indicated the unique community structure, on species, genera, class and phyla levels, of the culturable population recovered with plant-based culture media, being distinct from that obtained with the chemically-synthetic culture media. Proteobacteria were the dominant (78.8%) on plant-based agar culture medium compared to only 31% on nutrient agar, while Firmicutes prevailed on nutrient agar (69%) compared to the plant-based agar culture media (18.2%). Bacteroidetes, represented by Chryseobacterium indologenes, was only reported (3%) among the culturable rhizobacteria community of the plant-based agar culture medium. PMID:26966571

Comparative performance of isolation methods using Preston broth, Bolton broth and their modifications for the detection of Campylobacter spp. from naturally contaminated fresh and frozen raw poultry meat.

PubMed

Seliwiorstow, T; De Zutter, L; Houf, K; Botteldoorn, N; Baré, J; Van Damme, I

2016-10-03

The performance of different isolation methods was evaluated for the detection of Campylobacter from naturally contaminated raw poultry meat. Therefore, fresh and frozen poultry meat samples were analysed using the standard procedure (ISO 10272-1:2006), enrichment in Preston broth, and enrichment in modified Bolton broth (supplemented with (i) potassium clavulanate (C-BB), (ii) triclosan (T-BB), (iii) polymyxin B (P-BB)). The enrichment cultures were streaked onto both modified charcoal cefoperazone deoxycholate agar (mCCDA) and RAPID'Campylobacter agar (RCA). Moreover, direct plating on mCCDA and RCA was performed to quantify Campylobacter. In total, 33 out of 59 fresh retail meat samples (55.9%) were Campylobacter positive. For both fresh and frozen poultry meat samples, enrichment in Bolton broth (ISO 10272-1:2006) resulted in a higher number of positive samples than enrichment in Preston broth. Supplementation of Bolton broth with potassium clavulanate (C-BB) and triclosan (T-BB) enhanced the Campylobacter recovery from fresh poultry meat compared to non-supplemented Bolton broth, although the use of C-BB was less applicable than T-BB for Campylobacter recovery from frozen samples. Additionally, the use of RCA resulted in a higher isolation rate compared to mCCDA. The present study demonstrates the impact of culture medium on the recovery of Campylobacter from fresh and frozen naturally contaminated poultry meat samples and can support laboratories in choosing the most appropriate culturing method to detect Campylobacter. Copyright © 2016 Elsevier B.V. All rights reserved.

Glutamine supplementation in cystic fibrosis: A randomized placebo-controlled trial.

PubMed

Forrester, Doug L; Knox, Alan J; Smyth, Alan R; Barr, Helen L; Simms, Rebecca; Pacey, Sarah J; Pavord, Ian D; Honeybourne, David; Dewar, Jane; Clayton, Andy; Fogarty, Andrew W

2016-03-01

Pulmonary infection and malnutrition in cystic fibrosis are associated with decreased survival. Glutamine has a possible anti-microbial effect, with a specific impact against Pseudomonas aeruginosa. We aimed to test the hypothesis that oral glutamine supplementation (21 g/day) for 8 weeks in adults with cystic fibrosis would decrease pulmonary inflammation and improve clinical status. The study design was a randomized double-blind placebo-controlled study design with an iso-nitrogenous placebo. The primary analysis was intention to treat, and the primary outcome was change in induced sputum neutrophils. Thirty-nine individuals were recruited and thirty-six completed the study. Glutamine supplementation had no impact on any of the outcome measures in the intention-to-treat analysis. In the per protocol analysis, glutamine supplementation was associated with an increase in induced sputum neutrophils (P = 0.046), total cells (P = 0.03), and in Pseudomonas isolation agar colony forming units (P = 0.04) compared to placebo. There was no effect of glutamine supplementation on markers of pulmonary inflammation in the intention-to-treat analysis. © 2015 Wiley Periodicals, Inc.

Lack of negative effects of the biological control agent Duddingtonia flagrans on soil nematodes and other nematophagous fungi.

PubMed

Saumell, C A; Fernández, A S; Echevarria, F; Gonçalves, I; Iglesias, L; Sagües, M F; Rodríguez, E M

2016-11-01

The possible environmental effects of the massive use of Duddingtonia flagrans for controlling sheep nematodes were evaluated in two regions. Non-supplemented faeces and faeces from sheep supplemented with D. flagrans were deposited three times on pasture plots and samples were collected 7 and 14 days post-deposition. Samples were cultured in agar-water (2%) with Panagrellus spp. to recover D. flagrans and other nematophagous fungi, and soil nematodes were extracted using Baermann funnels and counted. No significant differences in the populations of soil nematodes and fungi colonizing sheep faeces (P > 0.05) were observed between supplemented and non-supplemented groups, except in one sample. The topsoil in contact with the faeces was sampled 1-4 months post-deposition, revealing that, with one exception, D. flagrans did not persist in soil beyond 2 months post-deposition. Duddingtonia flagrans does not affect faecal colonization by other fungi and soil nematodes and, once deployed on pasture, does not survive for long periods in the environment.

Evaluation of the ability of four ESBL-screening media to detect ESBL-producing Salmonella and Shigella.

PubMed

Sturød, Kjersti; Dahle, Ulf R; Berg, Einar Sverre; Steinbakk, Martin; Wester, Astrid L

2014-09-04

The aim of this study was to compare the ability of four commercially available media for screening extended-spectrum beta-lactamase (ESBL) to detect and identify ESBL-producing Salmonella and Shigella in fecal samples. A total of 71 Salmonella- and 21 Shigella-isolates producing ESBL(A) and/or AmpC, were received at Norwegian Institute of Public Health between 2005 and 2012. The 92 isolates were mixed with fecal specimens and tested on four ESBL screening media; ChromID ESBL (BioMèrieux), Brilliance ESBL (Oxoid), BLSE agar (AES Chemunex) and CHROMagar ESBL (CHROMagar). The BLSE agar is a biplate consisting of two different agars. Brilliance and CHROMagar are supposed to suppress growth of AmpC-producing bacteria while ChromID and BLSE agar are intended to detect both ESBL(A) and AmpC. The total sensitivity (ESBL(A)+AmpC) with 95% confidence intervals after 24 hours of incubation were as follows: ChromID: 95% (90.4-99.6), Brilliance: 93% (87.6-98.4), BLSE agar (Drigalski): 99% (96.9-100), BLSE agar (MacConkey): 99% (96.9-100) and CHROMagar: 85% (77.5-92.5). The BLSE agar identified Salmonella and Shigella isolates as lactose-negative. The other agars based on chromogenic technology displayed Salmonella and Shigella flexneri isolates with colorless colonies (as expected). Shigella sonnei produced pink colonies, similar to the morphology described for E. coli. All four agar media were reliable in screening fecal samples for ESBL(A)-producing Salmonella and Shigella. However, only ChromID and BLSE agar gave reliable detection of AmpC-producing isolates. Identification of different bacterial species based on colony colour alone was not accurate for any of the four agars.

Supplementation of CHROMagar Candida Medium with Pal's Medium for Rapid Identification of Candida dubliniensis

PubMed Central

Sahand, Ismail H.; Moragues, María D.; Eraso, Elena; Villar-Vidal, María; Quindós, Guillermo; Pontón, José

2005-01-01

CHROMagar Candida medium is used for the isolation and identification of Candida species, but it does not differentiate Candida albicans from Candida dubliniensis. This differentiation can be achieved by using Pal's agar, which cannot be used in primary isolation. We have combined both media to obtain a new medium that can be used for the isolation and identification of C. dubliniensis in primary cultures. PMID:16272515

Somatic embryogenesis from flower explants of cocoa (Theobroma cacao L.).

PubMed

Silva, J J; Debergh, P

2001-01-01

Two types of flower explants, staminoides and petals, were used for in vitro induction of somatic embryos in cocoa. After 14 days in culture, we observed globular structures and callus formation on both types of explants. However, the better results were obtained on staminoides: 98.3% formed callus and 86.2% somatic embryos on Murashige and Skoog (1962) medium supplemented with sucrose, coconut water, 2,4-D, kinetin and agar.

Different culture media containing methyldopa for melanin production by Cryptococcus species.

PubMed

Menezes, Ralciane de Paula; Penatti, Mário Paulo Amante; Pedroso, Reginaldo dos Santos

2011-10-01

Melanin production by species of Cryptococcus is widely used to characterize C. neoformans complex in mycology laboratories. This study aims to test the efficacy of methyldopa from pharmaceutical tablet as a substrate for melanin production, to compare the production of melanin using different agar base added with methyldopa, and to compare the melanin produced in those media with that produced in Niger seed agar and sunflower seed agar by C. neoformans, C. laurentii, and C. albidus. Two isolates of each species, C. neoformans, C. laurentii, and C. albidus, and one of Candida albicans were used to experimentally detect conditions for melanin production. The following media were tested: Mueller-Hinton agar (MHA), brain and heart infusion agar (BHIA), blood agar base (BAB), and minimal medium agar (MMA), all added with methyldopa, and the media Niger seed agar (NSA) and sunflower seed agar (SSA). All isolates grew in most of the culture media after 24h. Strains planted on media BAB and BHIA showed growth only after 48h. All isolates produced melanin in MMA, MHA, SSA, and NSA media. Methyldopa in the form pharmaceutical tablet can be used as a substrate for melanin production by Cryptococcus species; minimal medium plus methyldopa was more efficient than the BAB, MHA, and BHIA in the melanin production; and NSA and SSA, followed by MMA added with methyldopa, were more efficient than other media studied for melanin production by all strains studied.

Penicillium gravinicasei, a new species isolated from cave cheese in Apulia, Italy.

PubMed

Anelli, Pamela; Peterson, Steve W; Haidukowski, Miriam; Logrieco, Antonio F; Moretti, Antonio; Epifani, Filomena; Susca, Antonia

2018-06-08

Several species of the genus Penicillium were isolated during a survey of the mycobiota of Apulian cave cheeses ripened in a cave in Gravina di Puglia, Italy. A novel species, Penicillium gravinicasei, is described in Penicillium section Cinnamopurpurea. Its taxonomic novelty was determined using a polyphasic approach, combining phenotypic, molecular (β-tubulin, calmodulin, ITS and DNA dependent RNA polymerase) DNA sequences and mycotoxin production data. Phylogenetic analyses of the RPB2 data showed that isolates of the novel species form a clade most closely related to Penicillium cinnamopurpureum and P. parvulum with high bootstrap support. The fungus did not produce ochratoxin A, citrinin, patulin, sterigmatocystin or aflatoxin B 1 on standard agar media. The novel species had a high growth rate on agar media supplemented with 5% NaCl, and could be distinguished from other Penicillium section Cinnamopurpurea species by phenotypic and molecular characteristics. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of Eu and Sm on Methylobacterium sp.

NASA Astrophysics Data System (ADS)

Hibi, Yoshihisa; Okuda, Masayo; Sakuma, Ryusuke; Iwama, Tomonori; Kawai, Keiichi

Eu and Sm have been widely used in high technology products. In this study the authors isolated a soil bacterium, identified as Methylobacterium sp. MAFF211642, which exhibited colonies on 1/100 nutrient agar, supplemented by 30µM Eu and Sm; the soil bacterium was found to exhibit larger colonies than those in the absence of these elements. However, when 0.5% methanol was added to the nutrient agar, only Sm was found to stimulate the growth. Other rare earth and metal elements did not affect or inhibit, regardless of the presence of methanol. Addition of both Sm and methanol to the nutrient broth increased the growth of this strain 10-fold in colony forming unit larger than when both were absent. When both methanol and Sm were added to the nutrient broth, specific activity of methanol dehydrogenase in a crude extract of the bacterium increased approximately 5.4-fold.

Chlamydospore production and germ-tube formation by auxotrophs of Candida albicans.

PubMed

Balish, E

1973-04-01

A prototrophic strain and 21 auxotrophic strains of Candida albicans were assessed for their capacity to produce chlamydospores and germ tubes. All of the mutants were able to produce germ-tubes in human serum but only two mutants produced them in defined medium with L-alpha-amino-n-butyric acid as the sole source of nitrogen. Most auxotrophs were not able to produce chlamydospores on corn meal agar with 1% Tween 80, but they could be induced to do so if the medium was supplemented with their growth requirement(s). Although L-cysteine was able to support the growth of two methionine mutants, it did not support chlamydospore formation when added to corn meal agar with 1% Tween 80. Mutants of C. albicans that do not form chlamydospores could be incorrectly identified in laboratories that rely on chlamydospore formation for identification.

Residual Agar Determination in Bacterial Spores by Electrospray Ionization Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wahl, Karen L.; Colburn, Heather A.; Wunschel, David S.

2010-02-15

Presented here is an analytical method to detect residual agar from a bacterial spore sample as an indication of culturing on an agar plate. This method is based on the resolubilization of agar polysaccharide from a bacterial spore sample, enzymatic digestion, followed by electrospray ionization tandem mass spectrometry (ESI-MSn) analysis for detection of a specific agar fragment ion. A range of Bacillus species and strains were selected to demonstrate the effectiveness of this approach. The characteristic agar fragment ion was detected in the spores grown on agar that were washed from 1 to 5 times, irradiated or non-irradiated and notmore » in the spores grown in broth. A sample containing approximately 108 spores is currently needed for confident detection of residual agar from culture on agar plates in the presence of bacterial spores with a limit of detection of approximately 1 ppm agar spiked into a broth-grown spore sample. The results of a proficiency test with 42 blinded samples are presented demonstrating the utility of this method with no false positives and only 3 false negatives for samples that were below the detection level of the method as documented.« less

Effect of lignin on water vapor barrier, mechanical, and structural properties of agar/lignin composite films.

PubMed

Shankar, Shiv; Reddy, Jeevan Prasad; Rhim, Jong-Whan

2015-11-01

Biodegradable composite films were prepared using two renewable resources based biopolymers, agar and lignin alkali. The lignin was used as a reinforcing material and agar as a biopolymer matrix. The effect of lignin concentration (1, 3, 5, and 10wt%) on the performance of the composite films was studied. In addition, the mechanical, water vapor barrier, UV light barrier properties, FE-SEM, and TGA of the films were analyzed. The agar/lignin films exhibited higher mechanical and UV barrier properties along with lower water vapor permeability compared to the neat agar film. The FTIR and SEM results showed the compatibility of lignin with agar polymer. The swelling ratio and moisture content of agar/lignin composite films were decreased with increase in lignin content. The thermostability and char content of agar/lignin composite films increased with increased lignin content. The results suggested that agar/lignin films have a potential to be used as a UV barrier food packaging material for maintaining food safety and extending the shelf-life of the packaged food. Copyright © 2015 Elsevier B.V. All rights reserved.

Factors Affecting Selectivity of Brilliant Green-Phenol Red Agar for Salmonellae

PubMed Central

Moats, W. A.; Kinner, J. A.

1974-01-01

Commercial brilliant green (BG)-sulfa agar was found to be nonselective toward a test series of Enterobacteriaceae. Various formulations of BG were prepared by using Trypticase soy agar (BBL) as a base. Results were more reproducible when BG dye was added after sterilization than before. Sulfonamides improved selectivity as compared with brilliant green alone. Sulfanilamide (SN) was slightly more selective for salmonellae than other sulfonamides tested. Bile salts and sodium dodecyl sulfate markedly reduced the toxicity of BG to all the test bacteria. Enterobacter strains were most difficult to inhibit. A combination of 5 mg of BG and 1 g of SN/liter prevented growth of Proteus mirabilis and Escherichia coli and retarded growth of Enterobacter strains. The BG-SN agars were superior in selectivity to a series of commercial agars tested, and numbers of salmonellae recovered on BG-SN agar and Trypticase soy agar (BBL) were the same. Brilliant green agars with various degrees of selectivity are described. PMID:4589120

Comparison of charcoal- and starch-based media for testing susceptibilities of Legionella species to macrolides, azalides, and fluoroquinolones.

PubMed Central

Pendland, S L; Martin, S J; Chen, C; Schreckenberger, P C; Danziger, L H

1997-01-01

We compared growth characteristics of 46 Legionella strains grown on buffered charcoal yeast extract alpha (BCYE alpha) agar and buffered starch yeast extract (BSYE) agar and MICs of macrolides, azalides, and fluoroquinolones for these organisms. Growth was poor and not reproducible on BSYE agar. Growth was excellent on BCYE alpha, and MICs were easy to interpret. BCYE alpha is superior to BSYE for testing susceptibilities of Legionella species by agar dilution. PMID:9350781

Aescin formation in calli and embryoids from cotyledon and stem explants of Aesculus hippocastanum L.

PubMed

Profumo, P; Caviglia, A M; Gastaldo, P

1994-11-01

Aescin in calli and embryoids obtained from both cotyledon and stem explants of Aesculus hippocastanum were investigated by HPLC. Determinations were carried out on tissues cultured in agarized medium supplemented with growth substances (2,4-dichlorophenoxyacetic acid; kinetin; 1-naphthaleneacetic acid). The results indicate that aescin was produced in all the analysed samples. The amount of active principle present in some samples was higher than that found in horse-chestnut seeds.

Introducing a Novel Media to Improve the Recovery of Culturable Bacteria from the Fish Parasite Anisakis spp. larvae (Nematoda: Anisakidae).

PubMed

Svanevik, Cecilie S; Lunestad, Bjørn T

2017-09-01

This paper describes a cultivation method to increase the recovery of bacteria from the marine muscle-invading parasitic nematode larvae of Anisakis spp. These larvae hold a high and complex population of accumulated bacteria, originating from seawater, crustaceans, fish, and marine mammals, all involved in the lifecycle of Anisakis. Two in-house agars based on fish juice prepared by either mechanical or enzymatic degradation of the fish tissue, were made. The Anisakis larvae were homogenised prior to cultivation on the in-house fish juice agars and the bacterial numbers and diversity were compared to those obtained applying the commercially available Marine Agar and Iron Agar Lyngby. Bacterial colonies of unique appearance were subcultured and identified by 16S rRNA gene sequencing. Totally three of twenty identified taxa were found on the in-house fish juice agars only. Fish juice agar prepared enzymatically would be the best supplementary agar, as this agar gave significantly higher heterotrophic plate counts, compared to mechanical preparation. The enzymatically prepared fish juice gave more suitable agar quality, was more resource efficient, and had apparently increased nutrient density and availability.

Use of agar agar stabilized milled zero-valent iron particles for in situ groundwater remediation

NASA Astrophysics Data System (ADS)

Schmid, Doris; Velimirović, Milica; Wagner, Stephan; Micić Batka, Vesna; von der Kammer, Frank; Hofmann, Thilo

2015-04-01

A major obstacle for use of nanoscale zero-valent iron (nZVI) particles as a nontoxic material for effective in situ degradation of chlorinated aliphatic hydrocarbons (CAHs) is the high production cost. For that reason, submicro-scale milled zero-valent iron particles were recently developed (milled ZVI, UVR-FIA, Germany) by grinding macroscopic raw materials of elementary iron as a cheaper alternative to products produced by solid-state reduction. However, milled ZVI particles tend to aggregate and due to the rather large particle size (d50= 11.9 µm) also rapidly sediment. To prevent aggregation and consequently sedimentation of milled ZVI particles and therefore improve the mobility after in situ application, the use of a stabilizer is considered in literature as a most promising option. In this study, milled ZVI particles (1 g L-1 of particle concentration) were stabilized by environmentally friendly polymer agar agar (>0.5 g L-1), which had a positive impact on the milled ZVI stability. Sedimentation rate was significantly decreased by increasing the suspension viscosity. Column transport experiments were performed for bare and agar agar stabilized milled ZVI particles in commercially available fine grained quartz sand (DORSILIT® Nr.8, Gebrüder Dorfner GmbH Co, Germany) and different porous media collected from brownfields. The experiments were carried out under field relevant injection conditions of 100 m d-1. The maximal travel distance (LT) of less than 10 cm was determined for non-stabilized suspension in fine grained quartz sand, while agar agar (1 g L-1) stabilized milled ZVI suspension revealed LT of 12 m. Similar results were observed for porous media from brownfields showing that mobility of agar agar stabilized particle suspensions was significantly improved compared to bare particles. Based on the mobility data, agar agar stabilized milled zero-valent iron particles could be used for in situ application. Finally, lab-scale batch degradation experiments were performed to determine the impact of agar agar on the reactivity of milled ZVI and investigate the apparent corrosion rate of particles by quantifying the hydrogen gas generated by anaerobic corrosion of milled ZVI. The results indicate that agar agar had a positive impact on the milled ZVI stability and mobility, however adverse impact on the reactivity towards trichloroethene (TCE) was observed compared to the non-stabilized material. On the other hand, this study shows that the apparent corrosion rate of non-stabilized and agar agar stabilized milled ZVI particles is in the same order of magnitude. These data indicate that the dechlorination pathway of TCE by agar agar stabilized milled ZVI particles is possibly impacted by blocking of the reactive sites and not hydrogen revealed during particles corrosion. Finally, calculated longevity of the particles based on the apparent corrosion rate is significantly prolonged compared to the longevity of the nZVI particles reported in previous studies. This research receives funding from the European Union's Seventh Framework Programme FP7/2007-2013 under grant agreement n°309517.

Mineralized agar-based nanocomposite films: Potential food packaging materials with antimicrobial properties.

PubMed

Malagurski, Ivana; Levic, Steva; Nesic, Aleksandra; Mitric, Miodrag; Pavlovic, Vladimir; Dimitrijevic-Brankovic, Suzana

2017-11-01

New mineralized, agar-based nanocomposite films (Zn-carbonate and Zn-phosphate/agar) were produced by a combination of in situ precipitation and a casting method. The presence of minerals significantly influenced the morphology, properties and functionality of the obtained nanocomposites. Reinforcement with the Zn-mineral phase improved the mechanical properties of the carbonate-mineralized films, but had a negligible effect on the phosphate-mineralized samples. Both nanocomposites showed improved optical and thermal properties, better Zn(II) release potential in a slightly acidic environment and exhibited antimicrobial activity against S. aureus. These results suggest that Zn-mineralized agar nanocomposite films could be potentially used as affordable, eco-friendly and active food packaging materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

Antimicrobial and physical-mechanical properties of agar-based films incorporated with grapefruit seed extract.

PubMed

Kanmani, Paulraj; Rhim, Jong-Whan

2014-02-15

The use of synthetic petroleum based packaging films caused serious environmental problems due to their difficulty in recycling and poor biodegradability. Therefore, present study was aimed to develop natural biopolymer-based antimicrobial packaging films as an alternative for the synthetic packaging films. As a natural antimicrobial agent, grapefruit seed extract (GSE) has been incorporated into agar to prepare antimicrobial packaging film. The films with different concentrations of GSE were prepared by a solvent casting method and the resulting composite films were examined physically and mechanically. In addition, the films were characterized by FE-SEM, XRD, FT-IR and TGA. The incorporation of GSE caused increase in color, UV barrier, moisture content, water solubility and water vapor permeability, while decrease in surface hydrophobicity, tensile strength and elastic modulus of the films. As the concentration of GSE increased from 0.6 to 13.3 μg/mL, the physical and mechanical properties of the films were affected significantly. The addition of GSE changed film microstructure of the film, but did not influence the crystallinity of agar and thermal stability of the agar-based films. The agar/GSE films exhibited distinctive antimicrobial activity against three test food pathogens, such as Listeria monocytogenes, Bacillus cereus and Escherichia coli. These results suggest that agar/GSE films have potential to be used in an active food packaging systems for maintaining food safety and extending the shelf-life of the packaged food. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of essential oils of oregano and nutmeg on growth and survival of Yersinia enterocolitica and Listeria monocytogenes in barbecued chicken.

PubMed

Firouzi, R; Shekarforoush, S S; Nazer, A H K; Borumand, Z; Jooyandeh, A R

2007-11-01

The in vitro effects of plant essential oils (EOs) against pathogenic bacteria are well known, yet few studies have addressed the effects of these compounds against pathogens associated with ready-to-cook foods. Experiments were conducted to determine the effectiveness of oregano and nutmeg EOs on the growth and survival of Yersinia enterocolitica and Listeria monocytogenes in broth culture and in Iranian barbecued chicken. Ready-to-cook Iranian barbecued chicken was prepared according to the common practice with 1, 2, and 3 microl/g of oregano and nutmeg EOs. The test and control (without EOs) samples were inoculated with Y. enterocolitica and L. monocytogenes to a final concentration of 6 to 7 log CFU/g and stored at 3, 8, and 20 degrees C. Microorganisms were counted just before and at 24, 48, and 72 h after storage based on growth on Yersinia selective agar supplemented with cefsulodine, igrasan, and novobiocin and on Listeria selective agar supplemented with nalidixic acid and acriflavin. In the broth culture system, the nutmeg EO had a greater effect on L. monocytogenes (MIC = 0.20 nicrol/ml) than did the oregano EO (MIC = 0.26 microl/ml). However, the oregano EO had a greater effect on Y. enterocolitica (MIC = 0.16 microl/ml) than did the nutmeg EO (MIC = 0.25 microl/ml). In ready-to-cook Iranian barbecued chicken, the log CFU per gram of both bacteria after up to 72 h of incubation was not decreased significantly by various combinations of oregano and nutmeg EOs (1, 2, and 3 microl/g) and storage temperatures (3, 8, and 20 degrees C) when compared with control samples (without EOs). Although examination of spices in culture media can yield accurate microbiological data, without complementary tests in foods these data are of limited value for assessing food safety.

Testing of Compounds for Efficacy against Schistosomiasis.

DTIC Science & Technology

1987-08-25

Nostoc muscorU) has been grown (Liang, 1974) is placed in all glass aquaria, and plastic trays to serve as an additional food source. Snails in petri...supplemented with blue-green algae ( Nostoc muscoru) and mud forms the diet of stock snails in glass aquaria as well as those kept in plastic trays. The agar...green algae ( Nostoc muscorum) and water is used for rearing young * snails and maintaining both pre-patent and patent snails V (Liang, 1974); 3) a petri

Laboratory Evaluation of the Clean Earth Technologies Decontamination Solutions for Chemical and Biological Agents

DTIC Science & Technology

2008-01-01

TA. The DAAMs tubes are analyzed using a Marks UNITY/ULTRA thermal desorption system coupled to an Agilent 6890N gas chromatography -mass selective...tryptic- soy broth (TSB) or tryptic- soy agar (TSA). Frozen stock of bacterial cells, stored at -80 ’C in TSB supplemented with glycerol to a final...NNRidl) were prepared, heat-treated and ethanol-treated before staining with Malachite Green and viewed under oil immersion lens. The green to dark blue

Performance of CHROMagar Selective Medium and Oxacillin Resistance Screening Agar Base for Identifying Staphylococcus aureus and Detecting Methicillin Resistance

PubMed Central

Kluytmans, Jan; Van Griethuysen, Arjanne; Willemse, Piet; Van Keulen, Peter

2002-01-01

Two new selective media, oxacillin resistance screening agar base (ORSAB) and CHROMagar Staph aureus (CSA), were evaluated for identification of Staphylococcus aureus and for screening of methicillin resistance by addition of antimicrobial agents to these media. A well-defined collection consisting of 1,140 staphylococci was used. A total of 624 were S. aureus, of which 358 were methicillin susceptible and 266 were methicillin resistant, and 516 were coagulase-negative staphylococci. The methicillin-resistant S. aureus (MRSA) strains were selected based on the results of phage typing; 247 different types were included in the analysis. For identification of S. aureus, both media performed better after 24 h than after 48 h. The sensitivities at 24 h were comparable (CSA, 98.6%; ORSAB, 97.1%), but the specificity of CSA was significantly higher (CSA, 97.1%; ORSAB, 92.1%). For screening of methicillin resistance, antibiotic supplements were added to both media. The sensitivity was lower after 24 h (CSA, 58.6%; ORSAB, 84.2%) and increased significantly after 48 h (CSA, 77.5%; ORSAB, 91.4%). At both time intervals ORSAB was significantly more sensitive than CSA. However, the specificities of both media were high after 24 h (CSA, 99.1%; ORSAB, 98.3%) and decreased significantly after 48 h of incubation (CSA, 94.7%; ORSAB, 95.5%). In conclusion, for identification of S. aureus, CSA is more accurate than ORSAB because of a significantly higher specificity. For screening of MRSA, ORSAB performs better than CSA, but the usefulness in clinical practice is limited because a significant number of strains are not detected. PMID:12089266

Melanogenic actinomycetes from rhizosphere soil-antagonistic activity against Xanthomonas oryzae and plant-growth-promoting traits.

PubMed

Muangham, Supattra; Pathom-Aree, Wasu; Duangmal, Kannika

2015-02-01

A total of 210 melanogenic actinomycetes were isolated from 75 rhizospheric soils using ISP6 and ISP7 agar supplemented with antifungal and antibacterial agents. Their morphological characteristics and the presence of ll-diaminopimelic acid in whole-cell hydrolyzates revealed that all isolates belonged to the genus Streptomyces. Their ability to inhibit the growth of 2 pathogenic rice bacteria, Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola, was observed using the agar overlay method. The results indicated that 61.9% of the isolates could inhibit at least one of the tested rice pathogens. Among these, isolate TY68-3 showed the highest antibacterial activity and siderophore production. The 16S rRNA gene sequence analysis of 46 representative isolates revealed that isolates with high similarity to Streptomyces bungoensis were frequently found. The present study indicated the potential of melanogenic actinomycetes for use as biocontrol agents against X. oryzae as well as their diversity in rhizospheric soils.

Growth-promoting Properties of Different Solid Nutrient Media Evaluated with Stressed and Unstressed Micro-organisms: Prestudy for the Validation of a Rapid Sterility Test.

PubMed

Gray, Jennifer Claire; Staerk, Alexandra; Berchtold, Manfred; Hecker, Werner; Neuhaus, Gunther; Wirth, Andreas

2010-01-01

Currently, sterility testing in the pharmaceutical industry-a mandatory release test for all sterile drug products-takes an incubation time of at least 14 days and is based on liquid media according to the pharmacopoeias. The search is on for a rapid sterility test to reduce this rather long time frame. For this we have chosen the Millipore Milliflex Rapid Microbiology Detection System, which is based on solid nutrient media. As a prerequisite for the validation of this rapid sterility test, a solid nutrient medium promoting the growth of stressed and unstressed micro-organisms replacing tryptic soy broth and fluid thioglycollate medium from the traditional sterility test had to be found. For this a wide variety of appropriate nutrient media were evaluated. After a prestudy with 10 different nutrient agar media, tryptic soy agar, Center for Disease Control (CDC) anaerobic blood agar, Schaedler blood agar, and Difco brewer anaerobic agar were tested in detail using a range of 22 micro-organisms (7 ATCC strains and 15 production site-specific strains). These strains were inoculated in their unstressed and in a stressed state. Stress was evoked by heat treatment and nutrient starvation in the case of the sporulating bacteria. This stress effect-resulting in deceleration in growth-was experimentally confirmed based on growth curve analysis. It was statistically evaluated which media and which incubation temperatures are best suitable. The resulting data showed that Schaedler blood agar has the best growth-promoting properties among the agars tested and is going to be used in the rapid sterility test with the incubation temperatures 20-25 °C for aerobes, 30-35 °C for aerobes, and also 30-35 °C for anaerobic micro-organisms.

Presence and changes in populations of yeasts on raw and processed poultry products stored at refrigeration temperature.

PubMed

Ismail, S A; Deak, T; El-Rahman, H A; Yassien, M A; Beuchat, L R

2000-12-05

A study was undertaken to determine populations and profiles of yeast species on fresh and processed poultry products upon purchase from retail supermarkets and after storage at 5 degrees C until shelf life expiration, and to assess the potential role of these yeasts in product spoilage. Fifty samples representing 15 commercial raw, marinated, smoked, or roasted chicken and turkey products were analyzed. Yeast populations were determined by plating on dichloran rose bengal chloramphenicol (DRBC) agar and tryptone glucose yeast extract (TGY) agar. Proteolytic activity was determined using caseinate and gelatin agars and lipolytic activity was determined on plate count agar supplemented with tributyrin. Populations of aerobic microorganisms were also determined. Initial populations of yeasts (log10 cfu/g) ranged from less than 1 (detection limit) to 2.89, and increased by the expiration date to 0.37-5.06, indicating the presence of psychrotrophic species. Highest initial populations were detected in raw chicken breast, wings, and ground chicken, as well as in turkey necks and legs, whereas roasted chicken and turkey products contained less than 1 log10 cfu/g. During storage, yeast populations increased significantly (P < or = 0.05) in whole chicken, ground chicken, liver, heart and gizzard, and in ground turkey and turkey sausage. Isolates (152 strains) of yeasts from poultry products consisted of 12 species. Yarrowia lipolytica and Candida zeylanoides were predominant, making up 39 and 26% of the isolates, respectively. Six different species of basidiomycetous yeasts representing 24% of the isolates were identified. Most Y. lipolytica strains showed strong proteolytic and lipolytic activities, whereas C. zeylanoides was weakly lipolytic. Results suggest that yeasts, particularly Y. lipolytica, may play a more prominent role than previously recognized in the spoilage of fresh and processed poultry stored at 5 degrees C.

Taking nature into lab: biomineralization by heavy metal resistant streptomycetes in soil

NASA Astrophysics Data System (ADS)

Schütze, E.; Weist, A.; Klose, M.; Wach, T.; Schumann, M.; Nietzsche, S.; Merten, D.; Baumert, J.; Majzlan, J.; Kothe, E.

2013-02-01

Biomineralization by heavy metal resistant streptomycetes was tested to evaluate the potential influence on metal mobilities in soil. Thus, we designed an experiment adopting conditions from classical laboratory methods to natural conditions prevailing in metal-rich soils with media spiked with heavy metals, soil agar, and nutrient enriched or unamended soil incubated with the bacteria. As a result, all strains were able to form struvite minerals on tryptic soy broth (TSB) media supplemented with AlCl2, MnCl2 and CuSO4, as well as on soil agar. Some strains additionally formed struvite on nutrient enriched contaminated and control soil, as well as on metal contaminated soil without addition of media components. In contrast, switzerite was exclusively formed on minimal media spiked with MnCl2 by four heavy metal resistant strains, and on nutrient enriched control soil by one strain. Hydrated nickel hydrogen phosphate was only crystallized on complex media supplemented with NiSO4 by most strains. Thus, mineralization is a~dominant property of streptomycetes, with different processes likely to occur under laboratory conditions and sub-natural to natural conditions. This new understanding may be transferred to formation of minerals in rock and sediment evolution, to ore deposit formation, and also might have implications for our understanding of biological metal resistance mechanisms. We assume that biogeochemical cycles, nutrient storage and metal resistance might be affected by formation and re-solubilization of minerals like struvite in soil at microscale.

Taking nature into lab: biomineralization by heavy metal-resistant streptomycetes in soil

NASA Astrophysics Data System (ADS)

Schütze, E.; Weist, A.; Klose, M.; Wach, T.; Schumann, M.; Nietzsche, S.; Merten, D.; Baumert, J.; Majzlan, J.; Kothe, E.

2013-06-01

Biomineralization by heavy metal-resistant streptomycetes was tested to evaluate the potential influence on metal mobilities in soil. Thus, we designed an experiment adopting conditions from classical laboratory methods to natural conditions prevailing in metal-rich soils with media spiked with heavy metals, soil agar, and nutrient-enriched or unamended soil incubated with the bacteria. As a result, all strains were able to form struvite minerals (MgNH4PO4• 6H2O) on tryptic soy broth (TSB)-media supplemented with AlCl3, MnCl2 and CuSO4, as well as on soil agar. Some strains additionally formed struvite on nutrient-enriched contaminated and control soil, as well as on metal contaminated soil without addition of media components. In contrast, switzerite (Mn3(PO4)2• 7H2O) was exclusively formed on minimal media spiked with MnCl2 by four heavy metal-resistant strains, and on nutrient-enriched control soil by one strain. Hydrated nickel hydrogen phosphate was only crystallized on complex media supplemented with NiSO4 by most strains. Thus, mineralization is a dominant property of streptomycetes, with different processes likely to occur under laboratory conditions and sub-natural to natural conditions. This new understanding might have implications for our understanding of biological metal resistance mechanisms. We assume that biogeochemical cycles, nutrient storage and metal resistance might be affected by formation and re-solubilization of minerals like struvite in soil at microscale.

A one-step matrix application method for MALDI mass spectrometry imaging of bacterial colony biofilms.

PubMed

Li, Bin; Comi, Troy J; Si, Tong; Dunham, Sage J B; Sweedler, Jonathan V

2016-11-01

Matrix-assisted laser desorption/ionization imaging of biofilms cultured on agar plates is challenging because of problems related to matrix deposition onto agar. We describe a one-step, spray-based application of a 2,5-dihydroxybenzoic acid solution for direct matrix-assisted laser desorption/ionization imaging of hydrated Bacillus subtilis biofilms on agar. Using both an optimized airbrush and a home-built automatic sprayer, region-specific distributions of signaling metabolites and cannibalistic factors were visualized from B. subtilis cells cultivated on biofilm-promoting medium. The approach provides a homogeneous, relatively dry coating on hydrated samples, improving spot to spot signal repeatability compared with sieved matrix application, and is easily adapted for imaging a range of agar-based biofilms. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Isolation of Shiga toxin-producing Escherichia coli from fresh produce using STEC heart infusion washed blood agar with mitomycin-C.

PubMed

Lin, Andrew; Nguyen, Lam; Clotilde, Laurie M; Kase, Julie A; Son, Insook; Lauzon, Carol R

2012-11-01

The ability to detect and isolate Shiga toxin-producing Escherichia coli (STEC) remains a major challenge for food microbiologists. Although methods based on nucleic acids and antibodies have improved detection of STECs in foods, isolation of these bacteria remains arduous. STEC isolation is necessary for matching food, environmental, and clinical isolates during outbreak investigations and for distinguishing between pathogenic and nonpathogenic organisms. STEC heart infusion washed blood agar with mitomycin-C (SHIBAM) is a modification of washed sheep blood agar prepared by adding mitomycin-C and optimizing both the washed blood and base agar to better isolate STECs. Most STEC isolates produce a zone of hemolysis on SHIBAM plates and are easily distinguishable from background microbiota. Here, we present data supporting the use of SHIBAM to isolate STECs from fresh produce. SHIBAM was tested for accuracy in identifying STECs (365 of 410 STEC strains were hemolytic, and 63 of 73 E. coli strains that did not produce Shiga toxin were not hemolytic) and for recovery from artificially inoculated fresh produce (11 of 24 romaine lettuce samples and 6 of 24 tomato samples). STEC recovery with SHIBAM agar was greatly improved when compared with recovery on Levine's eosin-methylene blue agar as a reference method.

In vitro fermentation and prebiotic potential of novel low molecular weight polysaccharides derived from agar and alginate seaweeds.

PubMed

Ramnani, Priya; Chitarrari, Roberto; Tuohy, Kieran; Grant, John; Hotchkiss, Sarah; Philp, Kevin; Campbell, Ross; Gill, Chris; Rowland, Ian

2012-02-01

Fermentation properties and prebiotic potential of novel low molecular weight polysaccharides (LMWPs) derived from agar and alginate bearing seaweeds was investigated. Ten LMWPs were supplemented to pH, temperature controlled anaerobic batch cultures inoculated with human feces from three donors, in triplicate. Microbiota changes were monitored using Fluorescent in-situ hybridization and short chain fatty acids, the fermentation end products were analysed using gas chromatography. Of the ten LMWPs tested, Gelidium seaweed CC2253 of molecular weight 64.64 KDa showed a significant increase in bifidobacterial populations from log(10) 8.06 at 0 h to log(10) 8.55 at 24 h (p = 0.018). For total bacterial populations, alginate powder CC2238 produced a significant increase from log(10) 9.01 at 0 h to log(10) 9.58 at 24 h (p = 0.032). No changes were observed in the other bacterial groups tested viz. Bacteroides, Lactobacilli/Enterococci, Eubacterium rectale/Clostridium coccoides and Clostridium histolyticum. The polysaccharides also showed significant increases in total SCFA production, particularly acetic and propionic acids, indicating that they were readily fermented. In conclusion, some LMWPs derived from agar and alginate bearing seaweeds were fermented by gut bacteria and exhibited potential to be used a novel source of prebiotics. Copyright © 2011 Elsevier Ltd. All rights reserved.

Fabrication and characterization of biotissue-mimicking phantoms in the THz frequency range

NASA Astrophysics Data System (ADS)

Liakhov, E.; Smolyanskaya, O.; Popov, A.; Odlyanitskiy, E.; Balbekin, N.; Khodzitsky, M.

2016-08-01

The study revealed the most promising candidates for phantoms mimicking different biological tissues in the terahertz frequency range. Closest to biological tissues in terms of the refractive index appeared to be gelatin-based gels; in terms of the absorption coefficient they were agar-based gels. Gelatin is more stable in time, but requires special storage conditions to limit water evaporation. The dense structure of the agar-based phantom allows its use without mold and risk of damage. However, agar is a nutrient medium for bacteria and its parameters degrade even when the phantom form and water content are retained. Use of liquid suspensions of lecithin and milk powder are found to be extremely limited.

Candida neustonensis sp. nov., a novel ascomycetous yeast isolated from the sea surface microlayer in Taiwan.

PubMed

Chang, Chin-Feng; Lee, Ching-Fu; Liu, Shiu-Mei

2010-01-01

A new ascomycetous yeast species, Candida neustonensis is proposed in this study based on four strains (SN92(T), SN47, SJ22, SJ25) isolated from sea surface microlayer in Taiwan. These four yeast strains were morphologically, physiologically and phylogenetically identical to each other. No sexual reproduction was observed on 5% malt extract agar, corn meal agar, V8 agar, McClary's acetate agar and potato-dextrose agar. Phylogenetic analysis of the sequences of the D1/D2 domain of the large subunit (LSU) rRNA gene places C. neustonensis as a member of the Pichia guilliermondii clade, it also reveals that the phylogenetically closest relatives of C. neustonensis are C. fukuyamaensis (4.4% divergence), C. xestobii (4.4% divergence) and P. guilliermondii (4.5% divergence). C. neustonensis also is clearly distinguished from other known species in the P. guilliermondii clade based on the results of physiology tests. From these comparison analyses, the following novel yeast species is proposed: Candida neustonensis sp. nov., with strain SN92(T) (= BCRC 23108(T) = JCM 14892(T) = CBS 11061(T)) as the type strain.

Comparison of different sampling techniques and of different culture methods for detection of group B streptococcus carriage in pregnant women.

PubMed

El Aila, Nabil A; Tency, Inge; Claeys, Geert; Saerens, Bart; Cools, Piet; Verstraelen, Hans; Temmerman, Marleen; Verhelst, Rita; Vaneechoutte, Mario

2010-09-29

Streptococcus agalactiae (group B streptococcus; GBS) is a significant cause of perinatal and neonatal infections worldwide. To detect GBS colonization in pregnant women, the CDC recommends isolation of the bacterium from vaginal and anorectal swab samples by growth in a selective enrichment medium, such as Lim broth (Todd-Hewitt broth supplemented with selective antibiotics), followed by subculture on sheep blood agar. However, this procedure may require 48 h to complete. We compared different sampling and culture techniques for the detection of GBS. A total of 300 swabs was taken from 100 pregnant women at 35-37 weeks of gestation. For each subject, one rectovaginal, one vaginal and one rectal ESwab were collected. Plating onto Columbia CNA agar (CNA), group B streptococcus differential agar (GBSDA) (Granada Medium) and chromID Strepto B agar (CA), with and without Lim broth enrichment, were compared. The isolates were confirmed as S. agalactiae using the CAMP test on blood agar and by molecular identification with tDNA-PCR or by 16S rRNA gene sequence determination. The overall GBS colonization rate was 22%. GBS positivity for rectovaginal sampling (100%) was significantly higher than detection on the basis of vaginal sampling (50%), but not significantly higher than for rectal sampling (82%). Direct plating of the rectovaginal swab on CNA, GBSDA and CA resulted in detection of 59, 91 and 95% of the carriers, respectively, whereas subculturing of Lim broth yielded 77, 95 and 100% positivity, respectively. Lim broth enrichment enabled the detection of only one additional GBS positive subject. There was no significant difference between GBSDA and CA, whereas both were more sensitive than CNA. Direct culture onto GBSDA or CA (91 and 95%) detected more carriers than Lim broth enrichment and subculture onto CNA (77%). One false negative isolate was observed on GBSDA, and three false positives on CA. In conclusion, rectovaginal sampling increased the number GBS positive women detected, compared to vaginal and/or rectal sampling. Direct plating on CA and/or GBSDA provided rapid detection of GBS that was at least as sensitive and specific as the CDC recommended method of Lim broth subcultured onto non chromogenic agar.

Viability, Acid and Bile Tolerance of Spray Dried Probiotic Bacteria and Some Commercial Probiotic Supplement Products Kept at Room Temperature.

PubMed

Dianawati, Dianawati; Mishra, Vijay; Shah, Nagendra P

2016-06-01

Production of probiotic food supplements that are shelf-stable at room temperature has been developed for consumer's convenience, but information on the stability in acid and bile environment is still scarce. Viability and acid and bile tolerance of microencapsulated Bifidobacterium spp. and Lactobacillus acidophilus and 4 commercial probiotic supplements were evaluated. Bifidobacterium and L. acidophilus were encapsulated with casein-based emulsion using spray drying. Water activity (aw ) of the microspheres containing Bifidobacterium or L. acidophilus (SD GM product) was adjusted to 0.07 followed by storage at 25 °C for 10 wk. Encapsulated Bifidobacterium spp. and Lactobacillus acidophilus and 4 commercial probiotic supplement products (AL, GH, RE, and BM) were tested. Since commercial probiotic products contained mixed bacteria, selective media MRS-LP (containing L-cysteine and Na-propionate) and MRS-clindamycin agar were used to grow Bifidobacterium spp. or L. acidophilus, respectively, and to inhibit the growth of other strains. The results showed that aw had a strong negative correlation with the viability of dehydrated probiotics of the 6 products. Viable counts of Bifidobacterium spp. and L. acidophilus of SD GM, AL, and GH were between 8.3 and 9.2 log CFU/g, whereas that of BM and RE were between 6.7 and 7.3 log CFU/g. Bifidobacterium in SD GM, in AL, and in GH products and L. acidophilus in SD GM, in AL, and in BM products demonstrated high tolerance to acid. Most of dehydrated probiotic bacteria were able to survive in bile environment except L. acidophilus in RE product. Exposure to gastric juice influenced bacterial survivability in subsequent bile environment. © 2016 Institute of Food Technologists®

Antibacterial Effects against Various Foodborne Pathogens and Sensory Properties of Yogurt Supplemented with Panax ginseng Marc Extract

PubMed Central

Eom, Su Jin; Hwang, Ji Eun; Kim, Kee-Tae; Paik, Hyun-Dong

2017-01-01

Panax ginseng marc is produced from fresh ginseng roots during processing and is generally treated as industrial waste. The primary aim of this study was to improve its utilization in the dairy industry as a potential high-value resource. Yogurt was prepared from 11% skim milk powder, 0.1% pectin, 10% sucrose, and ginseng marc ethanol extract (GME, 0.5% and 1.0%) in milk, and was inoculated with a 0.02% yogurt culture (Lactobacillus acidophilus, Bifidobacterium longum, and Streptococcus thermophilus). After fermentation at 40°C for 6-8 h, the physicochemical properties of samples were analyzed by the AOAC, Kjeldahl, and Soxhlet methods. Sensory evaluation was performed based on consumer acceptability scores with a 7-point scale, and antimicrobial effects were measured by the agar plate method. The moisture, crude protein, crude fat, and ash contents of yogurt supplemented with 1% GME were 85.06±0.06%, 4.41±0.01%, 4.30±0.05%, and 0.81±0.03%, respectively, with no significant changes noted from those of yogurt without GME (control), except for an increase in the crude fat content. The sensory scores of color, flavor, texture, overall taste, and overall acceptance of yogurt supplemented with below 1% GME did not differ significantly (p<0.05) to those of the control yogurt. In addition, the growths of Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Escherichia coli, and Enterobacter sakazakii were inhibited during fermentation and storage. These results suggest that GME could be used in dairy products as a supplement and in the food industry as an antimicrobial material. PMID:29147103

Equivalency testing of TTC Tergitol 7 agar (ISO 9308-1:2000) with five culture media for the detection of E. coli in water samples in Greece.

PubMed

Mavridou, A; Smeti, E; Mandilara, G; Mandilara, G; Boufa, P; Vagiona-Arvanitidou, M; Vantarakis, A; Vassilandonopoulou, G; Pappa, O; Roussia, V; Tzouanopoulos, A; Livadara, M; Aisopou, I; Maraka, V; Nikolaou, E; Mandilara, G

2010-01-01

In this study ten laboratories in Greece compared the performance of reference method TTC Tergitol 7 Agar (with the additional test of beta-glucuronidase production) with five alternative methods, to detect E. coli in water, in line with European Water Directive recommendations. The samples were prepared by spiking drinking water with sewage effluent following a standard protocol. Chlorinated and non-chlorinated samples were used. The statistical analysis was based on the mean relative difference of confirmed counts and was performed in line with ISO 17994. The results showed that in total, three of the alternative methods (Chromocult Coliform agar, Membrane Lauryl Sulfate agar and Trypton Bilex-glucuronidase medium) were not different from TTC Tergitol 7 agar (TTC Tergitol 7 agar vs Chromocult Coliform agar, 294 samples, mean RD% 5.55; vs MLSA, 302 samples, mean RD% 1; vs TBX, 297 samples, mean RD% -2.78). The other two alternative methods (Membrane Faecal coliform medium and Colilert 18/ Quantitray) gave significantly higher counts than TTC Tergitol 7 agar (TTC Tergitol 7 agar vs MFc, 303 samples, mean RD% 8.81; vs Colilert-18/Quantitray, 76 samples, mean RD% 18.91). In other words, the alternative methods generated performance that was as reliable as, or even better than, the reference method. This study will help laboratories in Greece overcome culture and counting problems deriving from the EU reference method for E. coli counts in water samples.

The inability of Bacillus licheniformis perR mutant to grow is mainly due to the lack of PerR-mediated fur repression.

PubMed

Kim, Jung-Hoon; Yang, Yoon-Mo; Ji, Chang-Jun; Ryu, Su-Hyun; Won, Young-Bin; Ju, Shin-Yeong; Kwon, Yumi; Lee, Yeh-Eun; Youn, Hwan; Lee, Jin-Won

2017-06-01

PerR, a member of Fur family protein, is a metal-dependent H 2 O 2 sensing transcription factor that regulates genes involved in peroxide stress response. Industrially important bacterium Bacillus licheniformis contains three PerR-like proteins (PerR BL , PerR2, and PerR3) compared to its close relative Bacillus subtilis. Interestingly, unlike other bacteria including B. subtilis, no authentic perR BL null mutant could be established for B. licheniformis. Thus, we constructed a conditional perR BL mutant using a xylose-inducible promoter, and investigated the genes under the control of PerR BL . PerR BL regulon genes include katA, mrgA, ahpC, pfeT, hemA, fur, and perR as observed for PerR BS . However, there is some variation in the expression levels of fur and hemA genes between B. subtilis and B. licheniformis in the derepressed state. Furthermore, katA, mrgA, and ahpC are strongly induced, whereas the others are only weakly or not induced by H 2 O 2 treatment. In contrast to the B. subtilis perR null mutant which frequently gives rise to large colony phenotype mainly due to the loss of katA, the suppressors of B. licheniformis perR mutant, which can form colonies on LB agar, were all catalase-positive. Instead, many of the suppressors showed increased levels of siderophore production, suggesting that the suppressor mutation is linked to the fur gene. Consistent with this, perR fur double mutant could grow on LB agar without Fe supplementation, whereas perR katA double mutant could only grow on LB agar with Fe supplementation. Taken together, our data suggest that in B. licheniformis, despite the similarity in PerR BL and PerR BS regulon genes, perR is an essential gene required for growth and that the inability of perR null mutant to grow is mainly due to elevated expression of Fur.

Microbial diversity of culturable heterotrophs in the rhizosphere of salt marsh grass, Porteresia coarctata (Tateoka) in a mangrove ecosystem.

PubMed

Bharathkumar, Srinivasan; Paul, Diby; Nair, Sudha

2008-02-01

A study was conducted to understand the complexity of bacterial diversity of rhizosphere of Porteresia coarctata based on culture dependent method. A large number of bacteria were isolated on nutrient agar medium supplemented with 1% NaCl and the dominant ones were further analyzed with PCR-RFLP method. The sequence analyses of the dominant strains revealed that most of the sequences belonged to members of gamma proteobacteria, firmicutes, bacteroidetes and uncultured bacteria. The phylogenetic analysis of 16S rRNA gene sequences revealed close relationships to a wide range of clones or bacterial species of various divisions. These results afford an understanding of the role of rhizobacteria in alleviating salt stress in Porteresia coarctata expected to contribute towards long-term goal of improving plant-microbe interactions for salinity affected fields. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modeling of the Bacillus subtilis Bacterial Biofilm Growing on an Agar Substrate

PubMed Central

Wang, Xiaoling; Wang, Guoqing; Hao, Mudong

2015-01-01

Bacterial biofilms are organized communities composed of millions of microorganisms that accumulate on almost any kinds of surfaces. In this paper, a biofilm growth model on an agar substrate is developed based on mass conservation principles, Fick's first law, and Monod's kinetic reaction, by considering nutrient diffusion between biofilm and agar substrate. Our results show biofilm growth evolution characteristics such as biofilm thickness, active biomass, and nutrient concentration in the agar substrate. We quantitatively obtain biofilm growth dependence on different parameters. We provide an alternative mathematical method to describe other kinds of biofilm growth such as multiple bacterial species biofilm and also biofilm growth on various complex substrates. PMID:26355542

Modeling of the Bacillus subtilis Bacterial Biofilm Growing on an Agar Substrate.

PubMed

Wang, Xiaoling; Wang, Guoqing; Hao, Mudong

2015-01-01

Bacterial biofilms are organized communities composed of millions of microorganisms that accumulate on almost any kinds of surfaces. In this paper, a biofilm growth model on an agar substrate is developed based on mass conservation principles, Fick's first law, and Monod's kinetic reaction, by considering nutrient diffusion between biofilm and agar substrate. Our results show biofilm growth evolution characteristics such as biofilm thickness, active biomass, and nutrient concentration in the agar substrate. We quantitatively obtain biofilm growth dependence on different parameters. We provide an alternative mathematical method to describe other kinds of biofilm growth such as multiple bacterial species biofilm and also biofilm growth on various complex substrates.

Responsiveness of entomopathogenic fungi to menadione-induced oxidative stress.

PubMed

Azevedo, Rosana F F; Souza, Roberta K F; Braga, Gilberto U L; Rangel, Drauzio E N

2014-12-01

Entomopathogenic fungi are predisposed to ROS induced by heat and UV-A radiation when outside the insect host. When inside the host, they are subject to phagocytic cells that generate ROS to eliminate invading pathogens. The oxidative stress tolerance of the entomopathogenic fungi Aschersonia aleyrodis (ARSEF 430 and 10276), Aschersonia placenta (ARSEF 7637), Beauveria bassiana (ARSEF 252), Isaria fumosorosea (ARSEF 3889), Lecanicillium aphanocladii (ARSEF 6433), Metarhizium acridum (ARSEF 324), Metarhizium anisopliae (ARSEF 5749), Metarhizium brunneum (ARSEF 1187 and ARSEF 5626), Metarhizium robertsii (ARSEF 2575), Tolypocladium cylindrosporum (ARSEF 3392), Tolypocladium inflatum (ARSEF 4877), and Simplicillium lanosoniveum (ARSEF 6430 and ARSEF 6651) was studied based on conidial germination on a medium supplemented with menadione. Conidial germination was evaluated 24 h after inoculation on potato dextrose agar (PDA) (control) or PDA supplemented with menadione. The two Aschersonia species (ARSEF 430, 7637, and 10276) were the most susceptible fungi, followed by the two Tolypocladium species (ARSEF 3392 and 4877) and the M. acridum (ARSEF 324). Metarhizium brunneum (ARSEF 5626) and M. anisopliae (ARSEF 5749) were the most tolerant isolates with MIC 0.28 mM. All fungal isolates, except ARSEF 5626 and ARSEF 5749, were not able to germinate at 0.20 mM. Copyright © 2014 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Influence of different susceptibility testing methods and media on determination of the relevant fluconazole minimum inhibitory concentrations for heavy trailing Candida isolates with low-high phenotype.

PubMed

Alp, Sehnaz; Sancak, Banu; Hascelik, Gulsen; Arikan, Sevtap

2010-11-01

We investigated the incidence of trailing growth with fluconazole in 101 clinical Candida isolates (49 C. albicans and 52 C. tropicalis) and tried to establish the convenient susceptibility testing method and medium for fluconazole minimum inhibitory concentration (MIC) determination. MICs were determined by CLSI M27-A2 broth microdilution (BMD) and Etest methods on RPMI-1640 agar supplemented with 2% glucose (RPG) and on Mueller-Hinton agar supplemented with 2% glucose and 0.5 μg ml(-1) methylene blue (GMB). BMD and Etest MICs were read at 24 and 48 h, and susceptibility categories were compared. All isolates were determined as susceptible with BMD, Etest-RPG and Etest-GMB at 24 h. While all isolates were interpreted as susceptible at 48 h on Etest-RPG and Etest-GMB, one C. albicans isolate was interpreted as susceptible-dose dependent (S-DD) and two C. tropicalis isolates were interpreted as resistant with BMD. On Etest-RPG, trailing growth caused widespread microcolonies within the inhibition zone and resulted in confusion in MIC determination. On Etest-GMB, because of the nearly absence of microcolonies within the zone of inhibition, MICs were evaluated more easily. We conclude that, for the determination of fluconazole MICs of trailing Candida isolates, the Etest method has an advantage over BMD and can be used along with this reference method. Moreover, GMB appears more beneficial than RPG for the fluconazole Etest. © 2009 Blackwell Verlag GmbH.

Proliferation and glucosinolates accumulation of broccoli adventitious roots in liquid medium

NASA Astrophysics Data System (ADS)

Nhut, Nguyen Minh; Tien, Le Thi Thuy

2017-09-01

Cotyledons from 7-day-old in vitro broccoli seedling were used as explant source in adventitious root induction on MS medium supplemented with 30 g/l sucrose, 1.6 mg/l IBA and 7 g/l agar. Adventitious roots from cotyledons were transferred to liquid medium containing the same components as rooting medium for two weeks, then subcultured to MS medium with diferent sugar, macrominerals and casein hydrolysate concentrations. The best adventitious root growth was observed in half-strength MS medium supplemented with 40 g/l sucrose, 600 mg/l casein hydrolysate and 1.6 mg/l IBA (growth index of 4.00 in about 14 culture days with inoculum density of 1.0 g fresh weight / 30 ml of culture medium). The culturing process can be stopped on the 28th day for root biomass and on the 35th day for glucosinolates.

Antibiotic Resistance Patterns of Enterococci and Occurrence of Vancomycin-Resistant Enterococci in Raw Minced Beef and Pork in Germany

PubMed Central

Klein, Günter; Pack, Alexander; Reuter, Gerhard

1998-01-01

The food chain, especially raw minced meat, is thought to be responsible for an increase in the incidence of vancomycin-resistant enterococci (VRE) in human nosocomial infections. Therefore, 555 samples from 115 batches of minced beef and pork from a European Union-licensed meat-processing plant were screened for the occurrence of VRE. The processed meat came from 45 different slaughterhouses in Germany. Enterococci were isolated directly from Enterococcosel selective agar plates and also from Enterococcosel selective agar plates supplemented with 32 mg of vancomycin per liter. In addition, peptone broth was used in a preenrichment procedure, and samples were subsequently plated onto Enterococcosel agar containing vancomycin. To determine resistance, 209 isolates from 275 samples were tested with the glycopeptides vancomycin, teicoplanin, and avoparcin and 19 other antimicrobial substances by using a broth microdilution test. When the direct method was used, VRE were found in 3 of 555 samples (0.5%) at a concentration of 1.0 log CFU/g of minced meat. When the preenrichment procedure was used, 8% of the samples were VRE positive. Our findings indicate that there is a low incidence of VRE in minced meat in Germany. In addition, the resistance patterns of the VRE isolates obtained were different from the resistance patterns of clinical isolates. A connection between the occurrence of VRE in minced meat and nosocomial infections could not be demonstrated on the basis of our findings. PMID:9572958

Straw and Xylan Utilization by Pure Cultures of Nitrogen-Fixing Azospirillum spp

PubMed Central

Halsall, Dorothy M.; Turner, Graham L.; Gibson, Alan H.

1985-01-01

Azospirillum spp. were shown to utilize both straw and xylan, a major component of straw, for growth with an adequate combined N supply and also under N-limiting conditions. For most strains examined, a semisolid agar medium was satisfactory, but several strains appeared to be capable of slow metabolism of the agar. Subsequently, experiments were done with acid-washed sand supplemented with various carbon sources. In these experiments, authenticated laboratory strains, and all 16 recent field isolates from straw-amended soils, of both A. brasilense and A. lipoferum possessed the ability to utilize straw and xylan as energy sources for nitrogen fixation. Neither carboxymethyl cellulose nor cellulose was utilized. The strains and isolates differed in their abilities to utilize xylan and straw and in the efficiency of nitrogenase activity (CO2/C2H2 ratio). Reasonable levels of activity could be maintained for at least 14 days in the sand cultures. Nitrogenase activity (acetylene reduction) was confirmed by 15N2 incorporation. The level of nitrogenase activity observed was dependent on the time of the addition of acetylene to the culture vessels. PMID:16346730

Comparison of culture media, simplate, and petrifilm for enumeration of yeasts and molds in food.

PubMed

Taniwaki, M H; Silva, N; Banhe, A A; Iamanaka, B T

2001-10-01

The efficacy of three culture media, dichloran rose bengal chloramphenicol (DRBC), dichloran 18% glycerol agar (DG18), and potato dextrose agar (PDA) supplemented with two antibiotics, were compared with the Simplate and Petrifilm techniques for mold and yeast enumeration. The following foods were analyzed: corn meal, wheat flour, cassava flour, bread crumbs, whole meal, sliced bread, ground peanuts, mozzarella cheese, grated parmesan cheese, cheese rolls, orange juice, pineapple pulp, pineapple cake, and mushroom in conserve. Correlation coefficients of DRBC versus PDA and DG18 for recovering total mold and yeast counts from the composite of 14 foods indicated that the three media were generally equivalent. Correlation coefficients for Petrifilm versus culture media were acceptable, although not as good as between culture media. Correlation coefficients of Simplate versus DRBC, DG18, PDA, and Petrifilm for recovering total yeasts and molds from a composite of 11 foods demonstrated that there was no equivalence between the counts obtained by Simplate and other culture media and Petrifilm, with significant differences observed for the most foods analyzed.

Films based on soy protein-agar blends for wound dressing: Effect of different biopolymer proportions on the drug release rate and the physical and antibacterial properties of the films.

PubMed

Rivadeneira, Josefina; Audisio, M C; Gorustovich, Alejandro

2018-04-01

No single material can provide all requirements for wound dressings. Here, we evaluated the influence of different soy protein isolate and agar proportions (3:1, 1:1, and 1:3) in blend films on some of their physical-chemical and antibacterial properties to elucidate their potential as wound dressings. The films were synthesized by the gel casting method and ciprofloxacin hydrochloride was incorporated into the films. Films were characterized based on their surface morphology, water uptake ability, and weight loss profile. Also, the ciprofloxacin hydrochloride release kinetics was quantified spectrophotometrically. The antibacterial effect was evaluated against Staphylococcus aureus and Pseudomonas aeruginosa strains. The soy protein isolate-agar ratio affected the water uptake of the films and the release profile of ciprofloxacin hydrochloride but not the weight loss profile. The amount of drug released decreased near 80% because of the decrease in agar content in the films. The release kinetics of ciprofloxacin hydrochloride data best fitted to the Korsmeyer-Peppas model, suggesting that the mechanism of drug release was mainly of the diffusion type. All ciprofloxacin hydrochloride-releasing soy protein isolate-agar films strongly inhibited the cell viability of the bacterial strains studied. We concluded that water uptake and ciprofloxacin hydrochloride release can be controlled by changing the soy protein isolate-agar proportion. The proportions did not lead to changes in the antibacterial strength of the films.

Improved soft-agar colony assay in a fluid processing apparatus.

PubMed

Forsman, A D; Herpich, A R; Chapes, S K

1999-01-01

The standard method for quantitating bone marrow precursor cells has been to count the number of colony-forming units that form in semisolid (0.3%) agar. Recently we adapted this assay for use in hardware, the Fluid Processing Apparatus, that is flown in standard payload lockers of the space shuttle. When mouse or rat macrophage colony-forming units were measured with this hardware in ground-based assays, we found significantly more colony growth than that seen in standard plate assays. The improved growth correlates with increased agar thickness but also appears to be due to properties inherent to the Fluid Processing Apparatus. This paper describes an improved method for determining bone marrow macrophage precursor numbers in semisolid agar.

Homogeneous Matrix Deposition on Dried Agar for MALDI Imaging Mass Spectrometry of Microbial Cultures

NASA Astrophysics Data System (ADS)

Hoffmann, Thomas; Dorrestein, Pieter C.

2015-11-01

Matrix deposition on agar-based microbial colonies for MALDI imaging mass spectrometry is often complicated by the complex media on which microbes are grown. This Application Note demonstrates how consecutive short spray pulses of a matrix solution can form an evenly closed matrix layer on dried agar. Compared with sieving dry matrix onto wet agar, this method supports analyte cocrystallization, which results in significantly more signals, higher signal-to-noise ratios, and improved ionization efficiency. The even matrix layer improves spot-to-spot precision of measured m/z values when using TOF mass spectrometers. With this technique, we established reproducible imaging mass spectrometry of myxobacterial cultures on nutrient-rich cultivation media, which was not possible with the sieving technique.

Sporotrichosis caused by Sporothrix globosa in Rio De Janeiro, brazil: case report.

PubMed

de Oliveira, Manoel Marques Evangelista; de Almeida-Paes, Rodrigo; de Medeiros Muniz, Mauro; de Lima Barros, Monica Bastos; Galhardo, Maria Clara Gutierrez; Zancope-Oliveira, Rosely Maria

2010-05-01

This report describes the first isolation of Sporothrix globosa from a Brazilian patient. A 77-year-old woman was examined for sporotrichosis infection. Histopathological examination of skin biopsy revealed chronic granulomatous infiltrate with microabcess. Furthermore, S. schenckii-like yeasts were evident as demonstrated by PAS and Grocott stains. The fungus was identified based on colony morphology on Sabouraud Dextrose Agar slants, Potato Dextrose Agar, and Corn Meal Agar, microscopic morphology on slides cultures, and assimilation of different carbon sources. The species confirmation was made by molecular methodology.

Clonal propagation of Stevia rebaudiana Bertoni by stem-tip culture.

PubMed

Tamura, Y; Nakamura, S; Fukui, H; Tabata, M

1984-10-01

Clonal propagation of Stevia rebaudiana has been established by culturing stem-tips with a few leaf primordia on an agar medium supplemented with a high concentration (10 mg/l) of kinetin. Anatomical examination has suggested that these multiple shoots originate from a number of adventitious buds formed on the margin of the leaf. Innumerable shoots can be obtained by repeating the cycle of multiple-shoot formation from a single stem-tip of Stevia. These shoots produce roots when transferred to a medium containing NAA (0.1 mg/l) without kinetin. The regenerated plantlets can be transplanted to soil.

Direct plating technique for enumeration of Listeria monocytogenes in foods.

PubMed

Golden, D A; Beuchat, L R; Brackett, R E

1988-01-01

The advantages and disadvantages of various techniques for detecting and enumerating Listeria monocytogenes in foods are reviewed, and results from a study designed to compare 14 direct plating media for their suitability to recover uninjured cells of L. monocytogenes from 4 foods are summarized. McBride Listeria agar (MLA), gum base nalidixic acid tryptone soy agar (GBNTSA), modified Despierres agar (MDA), and modified MLA (MMLA) performed best for recovering all inoculum populations from milk and ice cream mix. For Brie cheese, MLA, MDA, MMLA, and Dominguez Rodriguez isolation agar were superior for recovering L. monocytogenes; GBNTSA, MDA, MMLA, and Donnelly's Listeria enrichment agar were best for recovering the organism from cabbage. Direct plating procedures without prior enrichment can be utilized successfully for recovering L. monocytogenes from foods such as pasteurized milk and ice cream mix, which contain low populations of background microflora. However, recovery of L. monocytogenes from foods such as raw cabbage and Brie cheese, which contain high populations of other microorganisms, was not satisfactory using direct plating procedures.

Improving agar electrospinnability with choline-based deep eutectic solvents

USDA-ARS?s Scientific Manuscript database

One percent agar (% wt) was dissolved in the deep eutectic solvent (DES), (2-hydroxyethyl) trimethylammonium chloride/urea at a 1:2 molar ratio, and successfully electrospun into nanofibers. An existing electrospinning set-up, operated at 50 deg C, was adapted for use with an ethanol bath to collect...

Colwellia agarivorans sp. nov., an agar-digesting marine bacterium isolated from coastal seawater

USDA-ARS?s Scientific Manuscript database

A novel Gram-stain-negative, facultatively anaerobic, yellowish and agar-digesting marine bacterium, designated strain QM50**T, was isolated from coastal seawater in an aquaculture site near Qingdao, China. Phylogenetic analysis based on 16S rDNA sequences revealed that the novel isolate represented...

Chromogenic agar medium for detection and isolation of Escherichia coli serogroups O26, O45, O103, O111, O121, and O145 from fresh beef and cattle feces.

PubMed

Kalchayanand, Norasak; Arthur, Terrance M; Bosilevac, Joseph M; Wells, James E; Wheeler, Tommy L

2013-02-01

Non-O157 Shiga toxin-producing Escherichia coli (STEC) strains are clinically important foodborne pathogens. Unlike E. coli O157:H7, these foodborne pathogens have no unique biochemical characteristics to readily distinguish them from other E. coli strains growing on plating media. In this study, a chromogenic agar medium was developed in order to differentiate among non-O157 STEC strains of serogroups O26, O45, O103, O111, O121, and O145 on a single agar medium. The ability of this chromogenic agar medium to select and distinguish among these pathogens is based on a combination of utilization of carbohydrates, b -galactosidase activity, and resistance to selective agents. The agar medium in combination with immunomagnetic separation was evaluated and successfully allowed for the detection and isolation of these six serogroups from artificially contaminated fresh beef. The agar medium in combination with immunomagnetic separation also allowed successful detection and isolation of naturally occurring non-O157 STEC strains present in cattle feces. Thirty-five strains of the top six non-O157 STEC serogroups were isolated from 1,897 fecal samples collected from 271 feedlot cattle. This chromogenic agar medium could help significantly in routine screening for the top six non-O157 STEC serogroups from beef cattle and other food.

Homogeneous matrix deposition on dried agar for MALDI imaging mass spectrometry of microbial cultures.

PubMed

Hoffmann, Thomas; Dorrestein, Pieter C

2015-11-01

Matrix deposition on agar-based microbial colonies for MALDI imaging mass spectrometry is often complicated by the complex media on which microbes are grown. This Application Note demonstrates how consecutive short spray pulses of a matrix solution can form an evenly closed matrix layer on dried agar. Compared with sieving dry matrix onto wet agar, this method supports analyte cocrystallization, which results in significantly more signals, higher signal-to-noise ratios, and improved ionization efficiency. The even matrix layer improves spot-to-spot precision of measured m/z values when using TOF mass spectrometers. With this technique, we established reproducible imaging mass spectrometry of myxobacterial cultures on nutrient-rich cultivation media, which was not possible with the sieving technique. Graphical Abstract ᅟ.

Optical elastic scattering for early label-free identification of clinical pathogens

NASA Astrophysics Data System (ADS)

Genuer, Valentin; Gal, Olivier; Méteau, Jérémy; Marcoux, Pierre; Schultz, Emmanuelle; Lacot, Éric; Maurin, Max; Dinten, Jean-Marc

2016-03-01

We report here on the ability of elastic light scattering in discriminating Gram+, Gram- and yeasts at an early stage of growth (6h). Our technique is non-invasive, low cost and does require neither skilled operators nor reagents. Therefore it is compatible with automation. It is based on the analysis of the scattering pattern (scatterogram) generated by a bacterial microcolony growing on agar, when placed in the path of a laser beam. Measurements are directly performed on closed Petri dishes. The characteristic features of a given scatterogram are first computed by projecting the pattern onto the Zernike orthogonal basis. Then the obtained data are compared to a database so that machine learning can yield identification result. A 10-fold cross-validation was performed on a database over 8 species (15 strains, 1906 scatterograms), at 6h of incubation. It yielded a 94% correct classification rate between Gram+, Gram- and yeasts. Results can be improved by using a more relevant function basis for projections, such as Fourier-Bessel functions. A fully integrated instrument has been installed at the Grenoble hospital's laboratory of bacteriology and a validation campaign has been started for the early screening of MSSA and MRSA (Staphylococcus aureus, methicillin-resistant S. aureus) carriers. Up to now, all the published studies about elastic scattering were performed in a forward mode, which is restricted to transparent media. However, in clinical diagnostics, most of media are opaque, such as blood-supplemented agar. That is why we propose a novel scheme capable of collecting back-scattered light which provides comparable results.

Effect of genotype, gelling agent, and auxin on the induction of somatic embryogenesis in sweet potato (Ipomoea batatas Lam.).

PubMed

El Abidine Triqui, Zine; Guédira, Abdelkarim; Chlyah, Averil; Chlyah, Hassane; Souvannavong, Vongthip; Haïcour, Robert; Sihachakr, Darasinh

2008-03-01

Lateral buds of six cultivars of sweet potato were induced to form embryogenic callus in a culture medium solidified with two types of gelling agents, Agar or Gelrite, and supplemented with various concentrations of auxins, 2,4-D, 2,4,5-T and Picloram. Of the six cultivars screened, only three gave an embryogenic response. Best results with an average of 3.53% embryogenic response were obtained with the medium solidified with Agar, while in Gelrite only 0.45% of lateral buds gave rise to embryogenic callus. The interaction between the genotype and auxins was highly significant; particularly the optimal response was obtained with cv. Zho and 865 yielding 10.7 and 14.7% somatic embryogenesis, respectively, in the medium containing 2,4,5-T or Picloram. The plant conversion was dramatically improved by subculture of the embryogenic callus on the medium with the combination of 1 microM 2,4-D and 1 microM Kinetin or 5 microM ABA alone before transfer of mature embryos onto hormone-free medium. The embryogenic callus of sweet potato and its sustained ability to further regenerate plants have regularly been maintained for several years by frequent subculture in 5 microM 2,4,5-T or the combination of 10 microM 2,4-D and 1 microM BAP or kinetin. The embryo-derived plants seemed apparently genetically stable and similar to the hexaploid parental plants, based on morphological analysis and their ploidy level determined by using flow cytometry.

Individual based simulations of bacterial growth on agar plates

NASA Astrophysics Data System (ADS)

Ginovart, M.; López, D.; Valls, J.; Silbert, M.

2002-03-01

The individual based simulator, INDividual DIScrete SIMulations (INDISIM) has been used to study the behaviour of the growth of bacterial colonies on a finite dish. The simulations reproduce the qualitative trends of pattern formation that appear during the growth of Bacillus subtilis on an agar plate under different initial conditions of nutrient peptone concentration, the amount of agar on the plate, and the temperature. The simulations are carried out by imposing closed boundary conditions on a square lattice divided into square spatial cells. The simulator studies the temporal evolution of the bacterial population possible by setting rules of behaviour for each bacterium, such as its uptake, metabolism and reproduction, as well as rules for the medium in which the bacterial cells grow, such as concentration of nutrient particles and their diffusion. The determining factors that characterize the structure of the bacterial colony patterns in the presents simulations, are the initial concentrations of nutrient particles, that mimic the amount of peptone in the experiments, and the set of values for the microscopic diffusion parameter related, in the experiments, to the amount of the agar medium.

Enrichment of prostate cancer stem cells from primary prostate cancer cultures of biopsy samples

PubMed Central

Wang, Shunqi; Huang, Shengsong; Zhao, Xin; Zhang, Qimin; Wu, Min; Sun, Feng; Han, Gang; Wu, Denglong

2014-01-01

This study was to enrich prostate cancer stem cells (PrCSC) from primary prostate cancer cultures (PPrCC). Primary prostate cancer cells were amplified in keratinocyte serum-free medium with epidermal growth factor (EGF) and bovine pituitary extract (BPE), supplemented with leukemia inhibitory factor (LIF), stem cell factor (SCF) and cholera toxin. After amplification, cells were transferred into ultra-low attachment dishes with serum-free DMEM/F12 medium, supplemented with EGF, basic fibroblast growth factor (bFGF), bovine serum albumin (BSA), insulin, and N2 nutrition. Expression of cell-type-specific markers was determined by RT-qPCR and immunostaining. Tumorigenicity of enriched PrCSC was determined by soft agar assay and xenograft assay in NOD/SCID mice. Biopsy samples from 19 confirmed prostate cancer patients were used for establishing PPrCC, and 18 cases (95%) succeeded. Both basal marker (CK5) and luminal markers (androgen receptor and CK8) strongly co-expressed in most of PPrCC, indicating their basal epithelial origin. After amplification under adherent culture condition in vitro, transient amplifying cells were the dominant cells. Sphere formation efficiency (SFE) of passaged PPrCC was about 0.5%, which was 27 times lower than SFE of LNCaP (13.67%) in the same condition. Compared with adherent cells from PPrCC, prostasphere from PPrCC showed up regulated stem cell markers and increased tumorigenic potential in soft-agar assay. However, spheroid cells from PPrCC prostasphere failed to initiate tumor in xenograft assay in 6 months. Thus, PPrCC can be established and amplified from prostate cancer biopsy samples. Our modified sphere culture system can enrich PrCSC from PPrCC. PMID:24427338

Efficient callus formation and plant regeneration of goosegrass [Eleusine indica (L.) Gaertn.].

PubMed

Yemets, A I; Klimkina, L A; Tarassenko, L V; Blume, Y B

2003-02-01

Efficient methods in totipotent callus formation, cell suspension culture establishment and whole-plant regeneration have been developed for the goosegrass [ Eleusine indica (L.) Gaertn.] and its dinitroaniline-resistant biotypes. The optimum medium for inducing morphogenic calli consisted of N6 basal salts and B5 vitamins supplemented with 1-2 mg l(-1) 2,4-dichlorophenoxyacetic acid (2,4-D), 2 mg l(-1) glycine, 100 mg l(-1) asparagine, 100 mg l(-1) casein hydrolysate, 30 g l(-1) sucrose and 0.6% agar, pH 5.7. The presence of organogenic and embryogenic structures in these calli was histologically documented. Cell suspension cultures derived from young calli were established in a liquid medium with the same composition. Morphogenic structures of direct shoots and somatic embryos were grown into rooted plantlets on medium containing MS basal salts, B5 vitamins, 1 mg l(-1) kinetin (Kn) and 0.1 mg l(-1) indole-3-acetic acid (IAA), 3% sucrose, 0.6% agar, pH 5.7. Calli derived from the R-biotype of E. indica possessed a high resistance to trifluralin (dinitroaniline herbicide) and cross-resistance to a structurally non-related herbicide, amiprophosmethyl (phosphorothioamidate herbicide), as did the original resistant plants. Embryogenic cell suspension culture was a better source of E. indica protoplasts than callus or mesophyll tissue. The enzyme solution containing 1.5% cellulase Onozuka R-10, 0.5% driselase, 1% pectolyase Y-23, 0.5% hemicellulase and N(6) mineral salts with an additional 0.2 M KCl and 0.1 M CaCl(2) (pH 5.4-5.5) was used for protoplast isolation. The purified protoplasts were cultivated in KM8p liquid medium supplemented with 2 mg l(-1) 2,4-D and 0.2 mg l(-1) Kn.

Isolation of Escherichia coli Strains with AcrAB–TolC Efflux Pump-Associated Intermediate Interpretation or Resistance to Fluoroquinolone, Chloramphenicol and Aminopenicillin from Dogs Admitted to a University Veterinary Hospital

PubMed Central

SATO, Toyotaka; YOKOTA, Shin-ichi; ICHIHASHI, Risa; MIYAUCHI, Tomoka; OKUBO, Torahiko; USUI, Masaru; FUJII, Nobuhiro; TAMURA, Yutaka

2014-01-01

ABSTRACT Understanding the prevalence of antimicrobial-resistance and the relationship between emergence of resistant bacteria and clinical treatment can facilitate design of effective treatment strategies. We here examined antimicrobial susceptibilities of Escherichia coli isolated from dogs admitted to a university hospital (University hospital) and companion animal clinics (Community clinics) in the same city and investigated underlying multidrug-resistance mechanisms. The prevalence of E. coli with intermediate and resistant interpretations to ampicillin (AMP), enrofloxacin (ENR) and chloramphenicol (CHL) was higher in the University hospital than in the Community clinics cases. Use of antimicrobials, including fluoroquinolone, was also significantly higher in the University hospital than in the Community clinics cases. Upon isolation using ENR-supplemented agar plates, all ENR-resistant isolates had 3–4 nucleotide mutations that accompanied by amino acid substitutions in the quinolone-resistance-determining regions of gyrA, parC and parE, and 94.7% of all isolates derived from the University hospital showed AMP and/or CHL resistance and possessed blaTEM and/or catA1. The average mRNA expression levels of acrA, acrB and tolC and the prevalence of organic solvent tolerance, in isolates derived from ENR-supplemented agar plates were significantly higher in the University hospital than in the Community clinics isolates. Thus, E. coli derived from the University hospital cases more often showed concomitant decreased susceptibilities to aminopenicillins, fluoroquinolones and CHL than did those derived from the Community clinics; this was related to an active AcrAB–TolC efflux pump, in addition to acquisition of specific resistance genes and genetic mutations. PMID:24646457

Novel Single-Tube Agar-Based Test System for Motility Enhancement and Immunocapture of Escherichia coli O157:H7 by H7 Flagellar Antigen-Specific Antibodies

PubMed Central

Murinda, Shelton E.; Nguyen, Lien T.; Ivey, Susan J.; Almeida, Raul A.; Oliver, Stephen P.

2002-01-01

This paper describes a novel single-tube agar-based technique for motility enhancement and immunoimmobilization of Escherichia coli O157:H7. Motility indole ornithine medium and agar (0.4%, wt/vol) media containing either nutrient broth, tryptone broth, or tryptic soy broth (TSBA) were evaluated for their abilities to enhance bacterial motility. Twenty-six E. coli strains, including 19 O157:H7 strains, 1 O157:H− strain, and 6 generic E. coli strains, were evaluated. Test bacteria were stab inoculated in the center of the agar column, and tubes were incubated at 37°C for 18 to 96 h. Nineteen to 24 of the 26 test strains (73.1 to 92.3%) were motile in the different media. TSBA medium performed best and was employed in subsequent studies of motility enhancement and H7 flagellar immunocapture. H7 flagellar antiserum (30 and 60 μl) mixed with TSBA was placed as a band (1 ml) in the middle of an agar column separating the top (3-ml) and bottom (3-ml) agar layers. The top agar layer was inoculated with the test bacterial strains. The tubes were incubated at 37°C for 12 to 18 h and for 18 to 96 h. The specificity and sensitivity of the H7 flagellar immunocapture tests were 75 and 100%, respectively. The procedure described is simple and sensitive and could be adapted easily for routine use in laboratories that do not have sophisticated equipment and resources for confirming the presence of H7 flagellar antigens. Accurate and rapid identification of H7 flagellar antigen is critical for the complete characterization of E. coli O157:H7, owing to the immense clinical, public health, and economic significance of this food-borne pathogen. PMID:12454173

Effects of extracellular matrix proteins on macrophage differentiation, growth, and function: comparison of liquid and agar culture systems

NASA Technical Reports Server (NTRS)

Armstrong, J. W.; Chapes, S. K.; Spooner, B. S. (Principal Investigator)

1994-01-01

Both spaceflight and skeletal unloading suppress the haematopoietic differentiation of macrophages (Sonnenfeld et al., Aviat. Space Environ. Med., 61:648-653, 1990; Armstrong et al., J. Appl. Physiol., 75:2734-2739, 1993). The mechanism behind this reduction in haematopoiesis has yet to be elucidated. However, changes in bone marrow extracellular matrix (ECM) may be involved. To further understand the role of ECM products in macrophage differentiation, we have performed experiments evaluating the effects of fibronectin, laminin, collagen type I, and collagen type IV on macrophage development and function. Bone marrow-derived macrophages cultured on four different ECM substrates in liquid culture medium showed less growth than those cultured on plastic. Significant morphological differences were seen on each of the substrates used. Phenotypically and functionally, as measured by class II major histocompatibility molecule (MHCII) expression, MAC-2 expression, and the secretion of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), these macrophages were similar. In contrast, bone marrow-derived macrophages cultured in suspension, using agar, showed no difference in growth when exposed to ECM proteins. However, IL-6 and TNF-alpha secretion was affected by fibronectin, laminin, collagen type I, and collagen type IV in a concentration-dependent manner. We conclude that the ECM products fibronectin, laminin, collagen type I, and collagen type IV have profound effects on macrophage development and function. Additionally, we suggest that an ECM-supplemented agar culture system provides an environment more analogous to in vivo bone marrow than does a traditional liquid culture system.

Relationships between Respiration and Susceptibility to Azole Antifungals in Candida glabrata

PubMed Central

Brun, Sophie; Aubry, Christophe; Lima, Osana; Filmon, Robert; Bergès, Thierry; Chabasse, Dominique; Bouchara, Jean-Philippe

2003-01-01

Over the past two decades, the incidence of infections due to Candida glabrata, a yeast with intrinsic low susceptibility to azole antifungals, has increased markedly. Respiratory deficiency due to mutations in mitochondrial DNA (mtDNA) associated with resistance to azoles frequently occurs in vitro in this species. In order to specify the relationships between respiration and azole susceptibility, the effects of respiratory chain inhibitors on a wild-type isolate of C. glabrata were evaluated. Respiration of blastoconidia was immediately blocked after extemporaneous addition of potassium cyanide, whereas a 4-h preincubation was required for sodium azide. Antifungal susceptibility determined by a disk diffusion method on Casitone agar containing sodium azide showed a significant decrease in the susceptibility to azoles. Biweekly subculturing on Casitone agar supplemented with sodium azide was therefore performed. This resulted after 40 passages in the isolation of a respiration-deficient mutant, as suggested by its lack of growth on glycerol-containing agar. This respiratory deficiency was confirmed by flow cytometric analysis of blastoconidia stained with rhodamine 123 and by oxygraphy. Moreover, transmission electron microscopy and restriction endonuclease analysis of the mtDNA of mutant cells demonstrated the mitochondrial origin of the respiratory deficiency. Finally, this mutant exhibited cross-resistance to all the azoles tested. In conclusion, blockage of respiration in C. glabrata induces decreased susceptibility to azoles, culminating in azole resistance due to the deletion of mtDNA. This mechanism could explain the induction of petite mutations by azole antifungals which have been demonstrated to act directly on the mitochondrial respiratory chain. PMID:12604511

Rapid automated method for screening of enteric pathogens from stool specimens.

PubMed Central

Villasante, P A; Agulla, A; Merino, F J; Pérez, T; Ladrón de Guevara, C; Velasco, A C

1987-01-01

A total of 800 colonies suggestive of Salmonella, Shigella, or Yersinia species isolated on stool differential agar media were inoculated onto both conventional biochemical test media (triple sugar iron agar, urea agar, and phenylalanine agar) and Entero Pathogen Screen cards of the AutoMicrobic system (Vitek Systems, Inc., Hazelwood, Mo.). Based on the conventional tests, the AutoMicrobic system method yielded the following results: 587 true-negatives, 185 true-positives, 2 false-negatives, and 26 false-positives (sensitivity, 99%; specificity, 96%). Both true-positive and true-negative results were achieved considerably earlier than false results (P less than 0.001). The Entero Pathogen Screen card method is a fast, easy, and sensitive method for screening for Salmonella, Shigella, or Yersinia species. The impossibility of screening for oxidase-positive pathogens is a minor disadvantage of this method. PMID:3553230

Characterization of bionanocomposite films prepared with agar and paper-mulberry pulp nanocellulose.

PubMed

Reddy, Jeevan Prasad; Rhim, Jong-Whan

2014-09-22

Crystallized nanocellulose (CNC) was separated from paper-mulberry (Broussonetia kazinoki Siebold) bast pulp by sulfuric acid hydrolysis method and they were blended with agar to prepare bionanocomposite films. The effect of CNC content (1, 3, 5 and 10 wt% based on agar) on the mechanical, water vapor permeability (WVP), and thermal properties of the nanocomposites were studied. Changes of the cellulose fibers in structure, morphology, crystallinity, and thermal properties of the films were evaluated using FT-IR, TEM, SEM, XRD, and TGA analysis methods. The CNC was composed of fibrous and spherical or elliptic granules of nano-cellulose with sizes of 50-60 nm. Properties of agar film such as mechanical and water vapor barrier properties were improved significantly (p<0.05) by blending with the CNC. The tensile modulus and tensile strength of agar film increased by 40% and 25%, respectively, in the composite film with 5 wt% of CNC, and the WVP of agar film decreased by 25% after formation of nanocomposite with 3 wt% of CNC. The CNC obtained from the paper-mulberry bast pulp can be used as a reinforcing agent for the preparation of bio-nanocomposites, and they have a high potential for the development of completely biodegradable food packaging materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

Properties and characterization of agar/CuNP bionanocomposite films prepared with different copper salts and reducing agents.

PubMed

Shankar, Shiv; Teng, Xinnan; Rhim, Jong-Whan

2014-12-19

Various types of agar-based bio-nanocomposite (BNC) films were prepared by blending agar and six different copper nanoparticles (CuNPs) with different shapes and sizes obtained from three different sources of copper salts and two different reducing agents. The BNC films were characterized by UV-visible, FE-SEM, FT-IR, and XRD. The thermogravimetric study showed that the melting point of BNC films was increased when ascorbic acid was used as a reducing agent for CuNPs synthesis. Apparent surface color and transmittance of agar film was greatly influenced by the reinforcement of CuNPs. However, mechanical and water vapor barrier properties did not change significantly (p>0.05) by blending with CuNPs. Tensile modulus and tensile strength decreased slightly for all types of CuNPs reinforced while elongation at break slightly increased when CuNPs produced by ascorbic acid were blended. The agar bio-nanocomposite films showed profound antibacterial activity against both Gram-positive and Gram-negative food-borne pathogenic bacteria. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparison of Brilliant Green Agar and Hektoen Enteric Agar Media in the Isolation of Salmonellae from Food Products

PubMed Central

Goo, Velma Y. L.; Ching, George Q. L.; Gooch, John M.

1973-01-01

Brilliant Green (BG) agar and Hektoen enteric (HE) agar media were compared for their efficiency in isolating salmonellae from various food products. Of the 11,226 food specimens examined, 1,662 (or 14.9%) yielded salmonellae. Of this number, 1,475 (88.7%) were recovered from BG agar and 1,315 (79.1%) were recovered from HE agar media. The results indicate that BG agar is more effective in isolating salmonellae from food products. A smaller subsidiary study showed HE agar to be more selective than BG agar. Four hundred ten specimens yielded 92 nonlactose-fermenting isolants other than salmonellae on BG agar and only 11 such isolants on HE agar. PMID:4584576

New Chromogenic Agar Medium for the Identification of Candida spp.

PubMed Central

Cooke, Venitia M.; Miles, R. J.; Price, R. G.; Midgley, G.; Khamri, W.; Richardson, A. C.

2002-01-01

A new chromogenic agar medium (Candida diagnostic agar [CDA]) for differentiation of Candida spp. is described. This medium is based on Sabouraud dextrose agar (Oxoid CM41) and contains (per liter) 40.0 g of glucose, 10.0 g of mycological peptone, and 15.0 g of agar along with a novel chromogenic glucosaminidase substrate, ammonium 4-{2-[4-(2-acetamido-2-deoxy-β-d-glucopyranosyloxy)-3-methoxyphenyl]-vinyl}-1-(propan-3-yl-oate)-quinolium bromide (0.32 g liter−1). The glucosaminidase substrate in CDA was hydrolyzed by Candida albicans and Candida dubliniensis, yielding white colonies with deep-red spots on a yellow transparent background after 24 to 48 h of incubation at 37°C. Colonies of Candida tropicalis and Candida kefyr were uniformly pink, and colonies of other Candida spp., including Candida glabrata and Candida parapsilosis, were white. CDA was evaluated by using 115 test strains of Candida spp. and other clinically important yeasts and was compared with two commercially available chromogenic agars (Candida ID agar [bioMerieux] and CHROMagar Candida [CHROMagar Company Ltd.]). On all three agars, colonies of C. albicans were not distinguished from colonies of C. dubliniensis. However, for the group containing C. albicans plus C. dubliniensis, both the sensitivity and the specificity of detection when CDA was used were 100%, compared with values of 97.6 and 100%, respectively, with CHROMagar Candida and 100 and 96.8%, respectively, with Candida ID agar. In addition, for the group containing C. tropicalis plus C. kefyr, the sensitivity and specificity of detection when CDA was used were also 100%, compared with 72.7 and 98.1%, respectively, with CHROMagar Candida. Candida ID agar did not differentiate C. tropicalis and C. kefyr strains but did differentiate members of a broader group (C. tropicalis, C. kefyr, Candida lusitaniae plus Candida guilliermondii); the sensitivity and specificity of detection for members of this group were 94.7 and 93.8%, respectively. In addition to the increased sensitivity and/or specificity of Candida detection when CDA was used, differentiation of colony types on CDA (red spotted, pink, or no color) was unambiguous and did not require precise assessment of colony color. PMID:12089051

Evolutionary consequences of putative intra- and interspecific hybridiation in agaric fungi

Treesearch

Karen W. Hughes; Ronald H. Petersen; D. Jean Lodge; Sarah E. Bergemann; Kendra Baumgartner; Rodham E. Tulloss; Edgar Lickey; Joaquin. Cifuentes

2013-01-01

Agaric fungi of the southern Appalachian Mountains including Great Smoky Mountains National Park are often heterozygous for the rDNA internal transcribed spacer region (ITS) with .42% of collections showing some heterozygosity for indels and/or base-pair substitutions. For these collections, intra-individual haplotype divergence is typically less than 2%, but for 3% of...

In vitro anti-biofilm and anti-bacterial activity of Junceella juncea for its biomedical application

PubMed Central

Kumar, P; Selvi, S Senthamil; Govindaraju, M

2012-01-01

Objective To investigate the anti-biofilm and anti-bacterial activity of Junceella juncea (J. juncea) against biofilm forming pathogenic strains. Methods Gorgonians were extracted with methanol and analysed with fourier transform infrared spectroscopy. Biofilm forming pathogens were identified by Congo red agar supplemented with sucrose. A quantitative spectrophotometric method was used to monitor in vitro biofilm reduction by microtitre plate assay. Anti-bacterial activity of methanolic gorgonian extract (MGE) was carried out by disc diffusion method followed by calculating the percentage of increase with crude methanol (CM). Results The presence of active functional group was exemplified by FT-IR spectroscopy. Dry, black, crystalline colonies confirm the production of extracellular polymeric substances responsible for biofilm formation in Congo red agar. MGE exhibited potential anti-biofilm activity against all tested bacterial strains. The anti-bacterial activity of methanolic extract was comparably higher in Salmonella typhii followed by Escherichia coli, Vibrio cholerae and Shigella flexneri. The overall percentage of increase was higher by 50.2% to CM. Conclusions To conclude, anti-biofilm and anti-bacterial efficacy of J. juncea is impressive over biofilm producing pathogens and are good source for novel anti-bacterial compounds. PMID:23593571

Antifungal susceptibility testing of Malassezia yeast: comparison of two different methodologies.

PubMed

Rojas, Florencia D; Córdoba, Susana B; de Los Ángeles Sosa, María; Zalazar, Laura C; Fernández, Mariana S; Cattana, María E; Alegre, Liliana R; Carrillo-Muñoz, Alfonso J; Giusiano, Gustavo E

2017-02-01

All Malassezia species are lipophilic; thus, modifications are required in susceptibility testing methods to ensure their growth. Antifungal susceptibility of Malassezia species using agar and broth dilution methods has been studied. Currently, few tests using disc diffusion methods are being performed. The aim was to evaluate the in vitro susceptibility of Malassezia yeast against antifungal agents using broth microdilution and disc diffusion methods, then to compare both methodologies. Fifty Malassezia isolates were studied. Microdilution method was performed as described in reference document and agar diffusion test was performed using antifungal tablets and discs. To support growth, culture media were supplemented. To correlate methods, linear regression analysis and categorical agreement was determined. The strongest linear association was observed for fluconazole and miconazole. The highest agreement between both methods was observed for itraconazole and voriconazole and the lowest for amphotericin B and fluconazole. Although modifications made to disc diffusion method allowed to obtain susceptibility data for Malassezia yeast, variables cannot be associated through a linear correlation model, indicating that inhibition zone values cannot predict MIC value. According to the results, disc diffusion assay may not represent an alternative to determine antifungal susceptibility of Malassezia yeast. © 2016 Blackwell Verlag GmbH.

Virulence of Photobacterium damselae subsp. piscicida in cultured cobia Rachycentron canadum.

PubMed

Liu, Ping-Chung; Lin, Ji-Yang; Lee, Kuo-Kau

2003-01-01

An outbreak of serious mortality among the cultured cobia Rachycentron canadum (weighing 3 kg) characterized by the presence of whitish granulomatous deposits on the kidney, liver and spleen occurred in July of 2000 in Taiwan. A non-motile strain CP1 was isolated from kidney and/or liver on tryptic soy agar and/or brain heart infusion agar plates (both supplemented with 1% NaCl, w/v). This strain was characterized and identified as Photobacterium damselae subsp. piscicida using biochemical characteristics and Bionor mono-Pp tests. The bacterium and its extracellular products (ECP) were lethal to the cobia (weighing 10 g) with LD50 values of 1.03 x 10(4) colony forming units and 1.26 microg protein/g fish body weight, respectively. All the moribund/dead fish exhibited darkness in color with no gross or internal leasions. However, the bacteria could be reisolated from kidney and liver after bacterial challenge. The present results reveal that Ph. damselae subsp. piscicida is the causative agent of fish photobacteriosis in the cobia and the bacterium isolated from sub-adult cobia (chronic form) is virulent to young cobia causing acute form of the disease.

Isolation and characterization of pathogenic Vibrio alginolyticus from diseased cobia Rachycentron canadum.

PubMed

Liu, Ping-Chung; Lin, Ji-Yang; Hsiao, Pei-Tze; Lee, Kuo-Kau

2004-01-01

Outbreaks of serious mortality among cultured juvenile cobia Rachycentron canadum L. (weighing 8-10 g) characterized by lethargy, dark skin and ascites in the peritoneal cavity while some fish possessing damaged eyes occurred in July and August of 2001 in Taiwan. Fifteen motile bacterial strains were isolated from head kidney and/or the ascites on tryptic soy agar supplemented with 1% NaCl (TSA1) and/or thiosulphate citrate bile salt (TCBS) sucrose agar plates during the two outbreaks. All the isolates were characterized and identified as Vibrio alginolyticus on the basis of biochemical characteristics, and comparisons with those of the reference strain V. alginolyticus ATCC 17749. The strain C3c01 (a representative of the 15 similar field isolates), was virulent to the cobia with an LD50 value of 3.28 x 10(4) colony forming units/g fish body weight. All the moribund/dead fish exhibited lethargy, dark skin and ascites in the peritoneal cavity as that observed in natural outbreaks. The same bacteria could be reisolated from kidney and the ascites of fish after bacterial challenge using TSA1 and TCBS plates. The results reveal that V. alginolyticus is an infectious agent of vibriosis in the cobia.

Mutations in Arabidopsis thaliana genes involved in the tryptophan biosynthesis pathway affect root waving on tilted agar surfaces

NASA Technical Reports Server (NTRS)

Rutherford, R.; Gallois, P.; Masson, P. H.

1998-01-01

Arabidopsis thaliana roots grow in a wavy pattern upon a slanted surface. A novel mutation in the anthranilate synthase alpha 1 (ASA1) gene, named trp5-2wvc1, and mutations in the tryptophan synthase alpha and beta 1 genes (trp3-1 and trp2-1, respectively) confer a compressed root wave phenotype on tilted agar surfaces. When trp5-2wvc1 seedlings are grown on media supplemented with anthranilate metabolites, their roots wave like wild type. Genetic and pharmacological experiments argue that the compressed root wave phenotypes of trp5-2wvc1, trp2-1 and trp3-1 seedlings are not due to reduced IAA biosynthetic potential, but rather to a deficiency in L-tryptophan (L-Trp), or in a L-Trp derivative. Although the roots of 7-day-old seedlings possess higher concentrations of free L-Trp than the shoot as a whole, trp5-2wvc1 mutants show no detectable alteration in L-Trp levels in either tissue type, suggesting that a very localized shortage of L-Trp, or of a L-Trp-derived compound, is responsible for the observed phenotype.

Riboflavin induces Metarhizium spp. to produce conidia with elevated tolerance to UV-B, and upregulates photolyases, laccases and polyketide synthases genes.

PubMed

Pereira-Junior, R A; Huarte-Bonnet, C; Paixão, F R S; Roberts, D W; Luz, C; Pedrini, N; Fernandes, É K K

2018-02-23

The effect of nutritional supplementation of two Metarhizium species with riboflavin (Rb) during production of conidia was evaluated on (i) conidial tolerance (based on germination) to UV-B radiation and on (ii) conidial expression following UV-B irradiation, of enzymes known to be active in photoreactivation, viz., photolyase (Phr), laccase (Lac) and polyketide synthase (Pks). Metarhizium acridum (ARSEF 324) and Metarhizium robertsii (ARSEF 2575) were grown either on (i) potato dextrose agar medium (PDA), (ii) PDA supplemented with 1% yeast extract (PDAY), (iii) PDA supplemented with Rb (PDA+Rb), or (iv) PDAY supplemented with Rb (PDAY+Rb). Resulting conidia were exposed to 866·7 mW m -2 of UV-B Quaite-weighted irradiance to total doses of 3·9 or 6·24 kJ m -2 . Some conidia also were exposed to 16 klux of white light (WL) after being irradiated, or not, with UV-B to investigate the role of possible photoreactivation. Relative germination of conidia produced on PDA+Rb (regardless Rb concentration) or on PDAY and exposed to UV-B was higher compared to conidia cultivated on PDA without Rb supplement, or to conidia suspended in Rb solution immediately prior to UV-B exposure. The expression of MaLac3 and MaPks2 for M. acridum, as well as MrPhr2, MrLac1, MrLac2 and MrLac3 for M. robertsii was higher when the isolates were cultivated on PDA+Rb and exposed to UV-B followed by exposure to WL, or exposed to WL only. Rb in culture medium increases the UV-B tolerance of M. robertsii and M. acridum conidia, and which may be related to increased expression of Phr, Lac and Pks genes in these conidia. The enhanced UV-B tolerance of Metarhizium spp. conidia produced on Rb-enriched media may improve the effectiveness of these fungi in biological control programs. © 2018 The Society for Applied Microbiology.

Nemesia Root Hair Response to Paper Pulp Substrate for Micropropagation

PubMed Central

Labrousse, Pascal; Delmail, David; Decou, Raphaël; Carlué, Michel; Lhernould, Sabine; Krausz, Pierre

2012-01-01

Agar substrates for in vitro culture are well adapted to plant micropropagation, but not to plant rooting and acclimatization. Conversely, paper-pulp-based substrates appear as potentially well adapted for in vitro culture and functional root production. To reinforce this hypothesis, this study compares in vitro development of nemesia on several substrates. Strong differences between nemesia roots growing in agar or in paper-pulp substrates were evidenced through scanning electron microscopy. Roots developed in agar have shorter hairs, larger rhizodermal cells, and less organized root caps than those growing on paper pulp. In conclusion, it should be noted that in this study, in vitro microporous substrates such as paper pulp lead to the production of similar root hairs to those found in greenhouse peat substrates. Consequently, if agar could be used for micropropagation, rooting, and plant acclimatization, enhancement could be achieved if rooting stage was performed on micro-porous substrates such as paper pulp. PMID:22312323

Nemesia root hair response to paper pulp substrate for micropropagation.

PubMed

Labrousse, Pascal; Delmail, David; Decou, Raphaël; Carlué, Michel; Lhernould, Sabine; Krausz, Pierre

2012-01-01

Agar substrates for in vitro culture are well adapted to plant micropropagation, but not to plant rooting and acclimatization. Conversely, paper-pulp-based substrates appear as potentially well adapted for in vitro culture and functional root production. To reinforce this hypothesis, this study compares in vitro development of nemesia on several substrates. Strong differences between nemesia roots growing in agar or in paper-pulp substrates were evidenced through scanning electron microscopy. Roots developed in agar have shorter hairs, larger rhizodermal cells, and less organized root caps than those growing on paper pulp. In conclusion, it should be noted that in this study, in vitro microporous substrates such as paper pulp lead to the production of similar root hairs to those found in greenhouse peat substrates. Consequently, if agar could be used for micropropagation, rooting, and plant acclimatization, enhancement could be achieved if rooting stage was performed on micro-porous substrates such as paper pulp.

Direct Measurements of Drag Forces in C. elegans Crawling Locomotion

PubMed Central

Rabets, Yegor; Backholm, Matilda; Dalnoki-Veress, Kari; Ryu, William S.

2014-01-01

With a simple and versatile microcantilever-based force measurement technique, we have probed the drag forces involved in Caenorhabditis elegans locomotion. As a worm crawls on an agar surface, we found that substrate viscoelasticity introduces nonlinearities in the force-velocity relationships, yielding nonconstant drag coefficients that are not captured by original resistive force theory. A major contributing factor to these nonlinearities is the formation of a shallow groove on the agar surface. We measured both the adhesion forces that cause the worm’s body to settle into the agar and the resulting dynamics of groove formation. Furthermore, we quantified the locomotive forces produced by C. elegans undulatory motions on a wet viscoelastic agar surface. We show that an extension of resistive force theory is able to use the dynamics of a nematode’s body shape along with the measured drag coefficients to predict the forces generated by a crawling nematode. PMID:25418179

Phosphate-Catalyzed Hydrogen Peroxide Formation from Agar, Gellan, and κ-Carrageenan and Recovery of Microbial Cultivability via Catalase and Pyruvate.

PubMed

Kawasaki, Kosei; Kamagata, Yoichi

2017-11-01

Previously, we reported that when agar is autoclaved with phosphate buffer, hydrogen peroxide (H 2 O 2 ) is formed in the resulting medium (PT medium), and the colony count on the medium inoculated with environmental samples becomes much lower than that on a medium in which agar and phosphate are autoclaved separately (PS medium) (T. Tanaka et al., Appl Environ Microbiol 80:7659-7666, 2014, https://doi.org/10.1128/AEM.02741-14). However, the physicochemical mechanisms underlying this observation remain largely unknown. Here, we determined the factors affecting H 2 O 2 formation in agar. The H 2 O 2 formation was pH dependent: H 2 O 2 was formed at high concentrations in an alkaline or neutral phosphate buffer but not in an acidic buffer. Ammonium ions enhanced H 2 O 2 formation, implying the involvement of the Maillard reaction catalyzed by phosphate. We found that other gelling agents (e.g., gellan and κ-carrageenan) also produced H 2 O 2 after being autoclaved with phosphate. We then examined the cultivability of microorganisms from a fresh-water sample to test whether catalase and pyruvate, known as H 2 O 2 scavengers, are effective in yielding high colony counts. The colony count on PT medium was only 5.7% of that on PS medium. Catalase treatment effectively restored the colony count of PT medium (to 106% of that on PS medium). In contrast, pyruvate was not as effective as catalase: the colony count on sodium pyruvate-supplemented PT medium was 58% of that on PS medium. Given that both catalase and pyruvate can remove H 2 O 2 from PT medium, these observations indicate that although H 2 O 2 is the main cause of reduced colony count on PT medium, other unknown growth-inhibiting substances that cannot be removed by pyruvate (but can be by catalase) may also be involved. IMPORTANCE The majority of bacteria in natural environments are recalcitrant to laboratory culture techniques. Previously, we demonstrated that one reason for this is the formation of high H 2 O 2 levels in media prepared by autoclaving agar and phosphate buffer together (PT medium). In this study, we investigated the factors affecting H 2 O 2 formation from agar. H 2 O 2 formation is pH dependent, and ammonium ions promote this phosphate-catalyzed H 2 O 2 formation. Amendment of catalase or pyruvate, a well-known H 2 O 2 -scavenging agent, effectively eliminated H 2 O 2 Yet results suggest that growth-inhibiting factor(s) that cannot be eliminated by pyruvate (but can be by catalase) are present in PT medium. Copyright © 2017 American Society for Microbiology.

Phosphate-Catalyzed Hydrogen Peroxide Formation from Agar, Gellan, and κ-Carrageenan and Recovery of Microbial Cultivability via Catalase and Pyruvate

PubMed Central

Kamagata, Yoichi

2017-01-01

ABSTRACT Previously, we reported that when agar is autoclaved with phosphate buffer, hydrogen peroxide (H2O2) is formed in the resulting medium (PT medium), and the colony count on the medium inoculated with environmental samples becomes much lower than that on a medium in which agar and phosphate are autoclaved separately (PS medium) (T. Tanaka et al., Appl Environ Microbiol 80:7659–7666, 2014, https://doi.org/10.1128/AEM.02741-14). However, the physicochemical mechanisms underlying this observation remain largely unknown. Here, we determined the factors affecting H2O2 formation in agar. The H2O2 formation was pH dependent: H2O2 was formed at high concentrations in an alkaline or neutral phosphate buffer but not in an acidic buffer. Ammonium ions enhanced H2O2 formation, implying the involvement of the Maillard reaction catalyzed by phosphate. We found that other gelling agents (e.g., gellan and κ-carrageenan) also produced H2O2 after being autoclaved with phosphate. We then examined the cultivability of microorganisms from a fresh-water sample to test whether catalase and pyruvate, known as H2O2 scavengers, are effective in yielding high colony counts. The colony count on PT medium was only 5.7% of that on PS medium. Catalase treatment effectively restored the colony count of PT medium (to 106% of that on PS medium). In contrast, pyruvate was not as effective as catalase: the colony count on sodium pyruvate-supplemented PT medium was 58% of that on PS medium. Given that both catalase and pyruvate can remove H2O2 from PT medium, these observations indicate that although H2O2 is the main cause of reduced colony count on PT medium, other unknown growth-inhibiting substances that cannot be removed by pyruvate (but can be by catalase) may also be involved. IMPORTANCE The majority of bacteria in natural environments are recalcitrant to laboratory culture techniques. Previously, we demonstrated that one reason for this is the formation of high H2O2 levels in media prepared by autoclaving agar and phosphate buffer together (PT medium). In this study, we investigated the factors affecting H2O2 formation from agar. H2O2 formation is pH dependent, and ammonium ions promote this phosphate-catalyzed H2O2 formation. Amendment of catalase or pyruvate, a well-known H2O2-scavenging agent, effectively eliminated H2O2. Yet results suggest that growth-inhibiting factor(s) that cannot be eliminated by pyruvate (but can be by catalase) are present in PT medium. PMID:28821549

Growth of Desulfovibrio on the surface of agar media.

PubMed

Iverson, W P

1966-07-01

Growth of Desulfovibrio desulfuricans (API strain) was found to take place in an atmosphere of hydrogen on the agar surface of complex media, including yeast extract (Difco), and Trypticase Soy Agar (BBL) without any added reducing agents. For growth on a 2% yeast extract-agar surface in the absence of hydrogen (nitrogen atmosphere), sodium lactate was required in the medium. Growth on the surface of Trypticase Soy Agar (TSA) under nitrogen took place readily in the absence of an added hydrogen donor. A medium (TSA plus salts) is described based upon the addition of sodium lactate (4 ml per liter), magnesium sulfate (2 g per liter), and ferrous ammonium sulfate (0.05%) to TSA, which appears suitable for the isolation and growth of Desulfovibrio on the surface of agar plates in an atmosphere of hydrogen. Sodium lactate does not appear to be essential in this medium for good growth and sulfate reduction in a hydrogen atmosphere, but is essential in a nitrogen atmosphere. Growth of Desulfovibrio (hydrogen atmosphere) on the agar surface of media commonly used for its cultivation as well as on an inorganic medium containing bicarbonate as a source of carbon is poor and erratic unless inoculated (Desulfovibrio) plates of TSA plus salts are incubated in the same container with plates of these media. This stimulatory effect of incubation with inoculated plates of TSA plus salts medium appears to be due to as yet unidentified volatile material produced by D. desulfuricans when growing on this medium. Another volatile material, or possibly the identical material, appears to act similarly to a hydrogen donor.

Morphological identification of Candida species on glucose agar, rice extract agar and corn meal agar with and without Tween-80.

PubMed

Joshi, K R; Solanki, A; Prakash, P

1993-01-01

A comparative study for the identification of 32 known strains of Candida species on the basis of morphology on glucose agar, rice extract agar and corn meal agar with and without Tween 80 revealed that when Tween 80 is incorporated in the media identification is possible for 96.8% of the species within 48 hours on rice extract agar and for 96.8% of the species within 48 hours on rice extract agar and for 90.6% of the species on glucose agar. The germ tubes and chlamydospores were also produced more on rice extract agar than on 0.1% glucose agar. Rice extract agar with Tween 80 can be used as single medium for morphologic identification of Candida species. The inoculated medium is first incubated at 37 degrees C for 3 hours and examined for germ tube formation and then incubated at 25 degrees C for 24 to 72 hours and examined for appearance of chlamydospores and mycelial morphology.

Choline chloride based ionic liquid analogues as tool for the fabrication of agar films with improved mechanical properties

USDA-ARS?s Scientific Manuscript database

In the present paper, we test the suitability of Choline-Cl/urea (DES-U) and Choline-Cl/glycerol (DES-G) eutectic mixtures at 1:2 molar ratios for the production of agar biodegradable films. A three-step process is proposed: pre-solubilization of polymer in DES followed by compression-molding and s...

Effect of raceme-localized supplemental light on soybean reproductive abscission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Myers, R.L.; Brun, W.A.; Brenner, M.L.

The percentage of soybean (Glycine max (L.) Merr.) reproductive structures that abscise is a potentially important yield factor. To better understand the involvement of light in the abscission of reproductive structures, a series of in vitro raceme-culture and growth-chamber experiments were conducted. In the in vitro raceme-culture experiments, racemes with four to six flowers at or past anthesis were excised from the soybean plant (genotype IX93-100), embedded in a complete nutrient, solid agar medium, and subjected to various light treatments. A series of three experiments indicated that the racemes contain a photoreceptor, possibly phytochrome, capable of regulating sucrose accumulation. Inmore » each of the growth chamber studies, supplemental light was supplied directly to individual soybean flowers via fiber optic light guides. The light source increased the photon flux to the flowers by 10-fold. The first growth chamber experiment showed that flowers receiving supplemental light were more intense sinks for /sup 14/C-sucrose than were controls (intensity value of 1.0 vs 0.4 x 10/sup -7/, intensity = (dps of flower/dps of raceme)/(kg dry wt of flower)). In a second study, 42% of flowers treated with supplemental light set pods, while only 26% of control flowers set pods. A third experiment showed that red supplemental light produced 55% fruit set, compared to 41% set for far-red light, and 35% for controls. These experiments indicate that both photoassimilate accumulation and abscission in young soybean reproductive structures may be regulated by light quality.« less

Light transfer in agar immobilized microalgae cell cultures

NASA Astrophysics Data System (ADS)

Kandilian, Razmig; Jesus, Bruno; Legrand, Jack; Pilon, Laurent; Pruvost, Jérémy

2017-09-01

This paper experimentally and theoretically investigates light transfer in agar-immobilized cell cultures. Certain biotechnological applications such as production of metabolites secreted by photosynthetic microorganisms require cells to be immobilized in biopolymers to minimize contamination and to facilitate metabolite recovery. In such applications, light absorption by cells is one of the most important parameters affecting cell growth or metabolite productivity. Modeling light transfer therein can aid design and optimize immobilized-cell reactors. In this study, Parachlorella kessleri cells with areal biomass concentrations ranging from 0.36 to 16.9 g/m2 were immobilized in 2.6 mm thick agar gels. The average absorption and scattering cross-sections as well as the scattering phase function of P. kessleri cells were measured. Then, the absorption and transport scattering coefficients of the agar gel were determined using an inverse method based on the modified two-flux approximation. The forward model was used to predict the normal-hemispherical transmittance and reflectance of the immobilized-cell films accounting for absorption and scattering by both microalgae and the agar gel. Good agreement was found between the measured and predicted normal-hemispherical transmittance and reflectance provided absorption and scattering by agar were taken into account. Moreover, good agreement was found between experimentally measured and predicted mean rate of photon absorption. Finally, optimal areal biomass concentration was determined to achieve complete absorption of the incident radiation.

Preparation of nanocellulose from micro-crystalline cellulose: The effect on the performance and properties of agar-based composite films.

PubMed

Shankar, Shiv; Rhim, Jong-Whan

2016-01-01

A facile approach has been performed to prepare nanocellulose (NC) from micro-crystalline cellulose (MCC) and test their effect on the performance properties of agar-based composite films. The NC was characterized by STEM, XRD, FTIR, and TGA. The NC was well dispersed in distilled water after sonication and their size was in the range of 100-500nm. The XRD results revealed the crystallinity of NC. The crystallinity index of NC (0.71) was decreased compared to the MCC (0.81). The effect of NC or MCC content (1, 3, 5 and 10wt% based on agar) on the mechanical, water vapor permeability (WVP), and thermal properties of the composites were studied. The NC obtained from MCC can be used as a reinforcing agent for the preparation of biodegradable composites films for their potential use in the development of biodegradable food packaging materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of a selective myclobutanil agar (MBA) medium for the isolation of Fusarium species from asparagus fields.

PubMed

Vujanovic, Vladimir; Hamel, Chantal; Jabaji-Hare, Suha; St-Arnaud, Marc

2002-09-01

A new selective myclobutanil agar medium for the detection of Fusarium, species is proposed. Ten media formulations based on various selective agents (pentachloronitrobenzene (PCNB), Rose Bengal, malachite green, sodium hypochlorite, captan, benomyl, chlorotalonil, myclobutanil, thiram, and cupric sulfate) were compared. First, mycelium growth and colony appearance of Alternaria alternata, Aspergillus flavus, Cladosporium cladosporioides, Epicoccum nigrum, Fusarium sp., Fuisarium solani, Fusarium moniliforme, Fusarium oxysporum f.sp. dianthi, Penicillium sp., and Trichoderma viride isolates were compared. Second, the ability of the different media to isolate and enumerate fusaria from asparagus fields was evaluated. The myclobutanil-based medium showed the highest selectivity to Fusarium spp. growth but required a slightly longer incubation time (>5 d) than peptone-pentachloronitrobenzene-based agar (PPA) (< 5 d). PPA allowed a faster fusaria growth but also permited the growth of other moulds. The other media were less selective and did not allow to isolate fusaria or to differenciate them from other growing fungi.

21 CFR 582.7115 - Agar-agar.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Agar-agar. 582.7115 Section 582.7115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7115 Agar-agar. (a...

21 CFR 582.7115 - Agar-agar.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Agar-agar. 582.7115 Section 582.7115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Stabilizers § 582.7115 Agar-agar. (a...

Growth and mycotoxin production by Chaetomium globosum.

PubMed

Fogle, Matthew R; Douglas, David R; Jumper, Cynthia A; Straus, David C

2007-07-01

Chaetomium globosum, the most common species within this genus, produces chaetoglobosins A and C when cultured on building material. Relatively low levels of these compounds have been shown to be lethal to various tissue culture cell lines. This study had two major objectives: (1) to determine the frequency at which Chaetomium species are isolated in water-damaged buildings and (2) to examine the production of chaetoglobosins A and C in isolates of C. globosum obtained from different buildings. Out of 794 water-damaged buildings, Chaetomium species were isolated in 49% of these structures. C. globosum ATCC 16021 was grown on four different media: oatmeal agar (OA), potato dextrose agar (PDA), corn meal agar (CMA), and malt extract agar (MEA). After 4 weeks, fungal growth was evaluated based on colony diameter and the quantity of spores produced on agar plates. In addition, production of chaetoglobosin A and C was monitored using high performance liquid chromatography. Colony diameter, spore production, and mycotoxin production by C. globosum were the highest on OA. Out of 30 C. globosum isolates cultured on OA for 4 weeks, 16 produced detectable amounts of chaetoglobosin A and every isolate produced chaetoglobosin C.

Comparison of Chromogenic Selective Media for the Detection of Cronobacter spp. (Enterobacter sakazakii).

PubMed

Teramura, Hajime; Fukuda, Noriko; Okada, Yumiko; Ogihara, Hirokazu

2018-01-01

　The four types of chromogenic selective media that are commercially available in Japan were compared for establishing a Japanese standard method for detecting Cronobacter spp. based on ISO/TS 22964:2006. When assessed using 9 standard Cronobacter spp. strains and 29 non-Cronobacter strains, Enterobacter sakazakii isolation agar, Chromocult TM Enterobacter sakazakii agar, CHROMagar TM E. sakazakii, and XM-sakazakii agar demonstrated excellent inclusivity and exclusivity. Using the ISO/TS 22964:2006 method, the recovered numbers of 38 Cronobacter spp. strains, including 29 C. sakazakii isolates obtained from each medium, were equivalent, indicating that there was no significant difference (p > 0.05) among the four types of chromogenic selective media. Thus, we demonstrated that these four chromogenic selective media are suitable alternatives when using the standard method for detecting Cronobacter spp. in Japan, based on the ISO/TS 22964:2006.

Growth of Streptococcus mutans on various selective media.

PubMed

Emilson, C G; Bratthall, D

1976-07-01

The ability of Streptococcus mutans to grow on mitis-salivarius (MS) agar, MC agar, mitis-sucrose-bacitracin (MSB), BCY agar, and MM10 sucrose agar was studied. Batch cultures of S. mutans serotype a demonstrated no growth on MSB agar. Certain serotype d and g strains did not grow on MC agar. The yield for most strains of other serotypes on these selective media was lower compared with that on MS agar. The number of total colony-forming units on BCY and MM10 sucrose agar was similar to the blood agar results. Similar data were obtained when fermenter-grown strains, harvested in the middle or the end of the logarithmic growth phase, were used for inoculation of the various media. Enumeration of S. mutans from plaque samples plated on MC and MSB agar yielded about 75% of the counts obtained on MS or the nonselective medium. When the proportions of S. mutans were expressed as a percentage of the total cultivable flora, the selective media (MC and MSB agar) showed approximately 10% lower values than the MS, BCY, and MM10 sucrose agar.

Experimental hut evaluation of linalool spatial repellent agar gel against Anopheles gambiae sensu stricto mosquitoes in a semi-field system in Bagamoyo, Tanzania.

PubMed

Tambwe, Mgeni Mohamed; Mbeyela, Edgar Mtaki; Massinda, Brian Migamyo; Moore, Sarah Jane; Maia, Marta Ferreira

2014-12-05

Malaria vector control is in need of new tools to face its current challenges such as the spread of pyrethroid-resistance and the increase of outdoor feeding mosquitoes. New strategies such as spatial repellents need to be evaluated as supplemental tools to existing control measures such as insecticide treated bed nets and indoor residual spraying. Linalool is a naturally occurring terpene alcohol commonly found in flowers and spices with reportedly repellent properties. Four experimental huts fitted with exit traps and enclosed inside a large screened semi-field system were used for the evaluation. The tested spatial repellent product consisted of an agar gel emanator containing 73% linalool. Two rounds of experiments using a Latin square design were conducted to evaluate the efficacy of the linalool emanators compared to no treatment (negative control) and a transfluthrin coil (positive) against lab-reared disease free Anopheles gambiae s.s.. The emanators were hung inside experimental huts where two volunteers were sleeping unprotected. The outcome measures were repellency, % feeding inhibition, %mortality and post 24 h % mortality. Unlike the mosquito coil, the linalool emanators did not show any feeding inhibition, repellency or induced mortality compared to the negative control. On the other hand mosquitoes kept for 24 h post exposure were 3 times more likely to die after being exposed to two 73% linalool emanators than the negative control. Our results indicate that linalool agar gel emanators are not adequate as a spatial repellent against Anopheles gambiae s.s.. However adding linalool to known repellent formulations could be advantageous, not only because of its pleasant scent but also because of the delayed mortality effect it has on mosquitoes.

Use of spent mushroom substrates from Agaricus subrufescens (syn. A. blazei, A. brasiliensis) and Lentinula edodes productions in the enrichment of a soil-based potting media for lettuce (Lactuca sativa) cultivation: Growth promotion and soil bioremediation.

PubMed

Ribas, L C C; de Mendonça, M M; Camelini, C M; Soares, C H L

2009-10-01

This study aimed to assess physicochemical and microbiological properties of fresh spent mushroom substrates (SMSs)--without post-crop heat treatment--from Agaricus subrufescens and Lentinula edodes production to optimize the use of these residues in the soil enrichment for lettuce growth promotion and soil remediation. Organic matter and C content of both SMSs were high. Fresh A. subrufescens SMS was a good source of N, P and K. On the other hand, L. edodes SMS presented a lower concentration of these nutrients and a high level of immaturity. Both SMSs presented high electric conductivity values (2.5-3.4 mS/cm). Microbiological analysis, based upon enumeration of culturable bacteria (thermophilic and mesophilic) and fungi, and also evolution of CO(2), showed that SMSs played higher microbial diversity than soil control. Laccase activity from A. subrufescens SMS tended to remain constant during a 2-month period, while L. edodes SMS presented low laccase activity throughout the same period. Agaricus subrufescens and L. edodes were able to grow on a PDA (Potato Dextrose Agar) media supplemented with different concentrations of atrazine (1-50 microg/ml), degraded the herbicide, attaining rates of 35% and 26%, respectively. On experiments of lettuce growth promotion using a soil-based potting media with different SMS rates, 5% and 10% (dw) rates of A. subrufescens SMS resulted in higher lettuce aerial dry weights than the rates of 25% and 40%, the chemical fertilization (NPK) and the control (soil). At 10% supplementation, lettuce aerial dry weight increased 2.2 and 1.3 times compared to the control and the NPK treatment, respectively. Protein content increased along with SMS rates. Fresh A. subrufescens SMS was an excellent supplement for lettuce growth promotion and showed potential for remediation of biocides possibly due to improved microbial diversity and enzymatic activity. Fresh L. edodes SMS was not a good fertilizer, at least under the conditions tested. However, microbiological analysis showed that promising results may be achieved when using fresh L. edodes SMS for soil remediation.

Antibiotic content of selective culture media for isolation of Capnocytophaga species from oral polymicrobial samples.

PubMed

Ehrmann, E; Jolivet-Gougeon, A; Bonnaure-Mallet, M; Fosse, T

2013-10-01

In oral microbiome, because of the abundance of commensal competitive flora, selective media with antibiotics are necessary for the recovery of fastidious Capnocytophaga species. The performances of six culture media (blood agar, chocolate blood agar, VCAT medium, CAPE medium, bacitracin chocolate blood agar and VK medium) were compared with literature data concerning five other media (FAA, LB, TSBV, CapR and TBBP media). To understand variable growth on selective media, the MICs of each antimicrobial agent contained in this different media (colistin, kanamycin, trimethoprim, trimethoprim-sulfamethoxazole, vancomycin, aztreonam and bacitracin) were determined for all Capnocytophaga species. Overall, VCAT medium (Columbia, 10% cooked horse blood, polyvitaminic supplement, 3·75 mg l(-1) of colistin, 1·5 mg l(-1) of trimethoprim, 1 mg l(-1) of vancomycin and 0·5 mg l(-1) of amphotericin B, Oxoid, France) was the more efficient selective medium, with regard to the detection of Capnocytophaga species from oral samples (P < 0·001) and the elimination of commensal clinical species (P < 0·001). The demonstrated superiority of VCAT medium, related to its antibiotic content, made its use indispensable for the optimal isolation of Capnocytophaga species from polymicrobial samples. Isolation of Capnocytophaga species is important for the proper diagnosis and treatment of the systemic infections they cause and for epidemiological studies of periodontal flora. We showed that in pure culture, a simple blood agar allowed the growth of all Capnocytophaga species. Nonetheless, in oral samples, because of the abundance of commensal competitive flora, selective media with antibiotics are necessary for the recovery of Capnocytophaga species. The demonstrated superiority of VCAT medium made its use essential for the optimal detection of this bacterial genus. This work showed that extreme caution should be exercised when reporting the isolation of Capnocytophaga species from oral polymicrobial samples, because the culture medium is a determining factor. © 2013 The Society for Applied Microbiology.

The effect of vacuum packaging, EDTA, oregano and thyme oils on the microbiological quality of chicken's breast.

PubMed

Pavelková, Adriana; Kačániová, Miroslava; Horská, Elena; Rovná, Katarína; Hleba, Lukáš; Petrová, Jana

2014-10-01

The effect of ethylenediaminetetraacetate (EDTA), oregano (Origanum vulgare) and thyme (Thymus vulgaris) oils, on the chicken breast fillets was examined in this study. The chicken breast fillets were stored under vacuum packaging (VP), at 4 ± 0.5 °C for a period of 18 days. There were used the following treatments of chicken breast fillets: Air-packaged (AC, control samples), vacuum-packaged (VPC, control samples), VP with EDTA solution 1.50% w/w (VPEC, control samples), VP with oregano oil 0.20% v/w (VP + O) and VP with thyme oil 0.20% v/w, (VP + T). The quality assessment for vacuum packaging of the product in accordance with the terms above and EDTA treatment, oregano and thyme oil was established by microbiological analyzes. The microbiological properties as the total viable counts on Plate Count Agar, after incubation for 2 days at 37 °C and coliform bacteria on Violet Red Bile Glucose agar incubated at 37 °C for 24 h, lactobacilli on Rogosa and Sharpe agar after incubation 48-78 h at 37 °C in an aerobic atmosphere supplemented with carbon dioxide (5% CO2) and Pseudomonas aeruginosa on Pseudomonas Isolation agar (PIA, Oxoid, UK) after incubation at 48 h at 35 °C were monitored. The using of oregano, thyme oil and EDTA with combination of vacuum packaging has significant effects to reduction of all followed groups of microorganisms compared with control group without vacuum packaging and untreated control group. The natural preservatives can be used as alternatives to chemical additives which could extend the meat and meat products shelf life. The knowledge about them can have an important economic feedback by reducing losses attributed to spoilage and by allowing the products to reach distant and new markets. This study shows how using of natural antimicrobials can extend the shelf-life of the meat product. Copyright © 2013 Elsevier Ltd. All rights reserved.

Approaches for enhancing in situ detection of enterocin genes in thermized milk, and selective isolation of enterocin-producing Enterococcus faecium from Baird-Parker agar.

PubMed

Vandera, Elpiniki; Tsirka, Georgia; Kakouri, Athanasia; Koukkou, Anna-Irini; Samelis, John

2018-05-21

Enterococci are naturally selected for growth in thermized ewes'/goats' milk mixtures used for traditional cooked hard cheese processing in Greece. A culture-independent PCR-based approach was applied to detect the presence of enterocin-encoding genes in naturally culture-enriched thermized milk (TM). Portions of TM (63 °C, 30 s) collected from a commercial cheese plant before addition of starters were fermented at 37 °C for 48 h to facilitate growth of indigenous enterococci. The multiple enterocin-producing (m-Ent+) Enterococcus faecium KE82 and the nisin A-producing Lactococcus lactis subsp. cremoris M104 served as bacteriocin-positive inocula in separate TM treatments. The PCR results revealed a constant presence of the enterocin A, B and P genes in TM fermented naturally at 37 °C. Eleven out of 42 (26.2%) lactic isolates from the enriched TM cultures without inoculation were Ent+ E. faecium assigned to three biotypes. Biotype I (4 isolates) included single entA possessors, whereas biotype II (5 isolates) and biotype III (2 isolates) were m-Ent+ variants profiling entA-entB-entP and entA-entB genes, respectively. Biotype II displayed the strongest antilisterial activity in vitro. Surprisingly, 85.7% (6/7) of the m-Ent+ E. faecium were selectively isolated from Baird-Parker agar, reflecting their natural resistance to 0.01% tellurite contained in the egg yolk supplement. No cytolysin-positive E. faecalis or other Ent+ Enterococcus spp. were isolated. In conclusion, commercially thermized Greek milk is a natural pool or 'reservoir' of antagonistic Ent+ or m-Ent+ E. faecium strains that can be easily detected and recovered by applying this PCR-based approach to naturally fermented milks or cheese products. Copyright © 2018 Elsevier B.V. All rights reserved.

Liesegang bands versus random crystallites in Ag2Cr2O7 - Single and mixed gelled media

NASA Astrophysics Data System (ADS)

Ibrahim, Huria; El-Rassy, Houssam; Sultan, Rabih

2018-02-01

Liesegang patterns of silver dichromate (Ag2Cr2O7) are studied in two different gel media: agar and gelatin, based on the work of Lagzi and Ueyama (2009). Whereas in gelatin, standard Liesegang bands are obtained as a result of the interdiffusion of Ag+ and Cr2 O72-, random crystallites with dendritic ramifications are observed in agar. We revisit this phenomenon and demonstrate the proposed mechanism, wherein dense heterogeneous nucleation in gelatin leads to Liesegang bands, as opposed to surface nucleation in agar yielding crystallites. We use viscosity, pH measurements, and notably scanning electron microscopy (SEM) in this endeavor.

Enhanced recovery of Arcobacter spp. using NaCl in culture media and re-assessment of the traits of Arcobacter marinus and Arcobacter halophilus isolated from marine water and shellfish.

PubMed

Salas-Massó, Nuria; Andree, Karl B; Furones, M Dolors; Figueras, M José

2016-10-01

The genus Arcobacter is a relatively poorly known group of bacteria, and the number of new species and sequences from non-culturable strains has increased considerably in recent years. This study investigates whether using media that contain NaCl might help to improve the recovery of Arcobacter spp. from marine environments. To this aim, 62 water and shellfish samples were analysed in parallel, with both a commonly used culture method (enrichment in Arcobacter-CAT broth followed by culture on Blood Agar) and a new one that supplements the Arcobacter-CAT enrichment broth with 2.5% NaCl (w/v) followed by culturing on Marine Agar. The new method yielded ca. 40% more positive samples and provided a higher diversity of known (11 vs. 7) and unknown (7 vs. 2) Arcobacter species. Among the 11 known species recovered, Arcobacter marinus and Arcobacter halophilus were isolated only by this new method. No more strains of these species have been isolated since their original descriptions, both of which were based only on a single strain. In view of that, the phenotypic characteristics of these species are re-evaluated in the present study, using the new strains. Strains of A. halophilus had the same phenotypic profile as the type strain. However, some strains of A. marinus differed from the type strain in that they did not hydrolyse indoxyl-acetate, becoming, therefore, the first Arcobacter species to show a varying ability to hydrolyse indoxyl-acetate. This study shows to what extent a simple variation to the culture media can have a big influence on positive samples and on the community of species recovered. Copyright © 2016 Elsevier B.V. All rights reserved.

Detection of seasonal asymptomatic dermatophytes in Van cats.

PubMed

Ilhan, Ziya; Karaca, Mehmet; Ekin, Ismail Hakki; Solmaz, Hasan; Akkan, Hasan Altan; Tutuncu, Mehmet

2016-01-01

The Van cat is a domestic landrace found in the Van province of eastern Turkey. In this study, we aimed to determine the seasonal carriage of dermatophytes in Van cats without clinical lesions. A total of 264 hair specimens were collected from clinically healthy cats in and around the Van Province. Of these samples, 30.3% were obtained in spring, 30.6% in summer, 16.6% in autumn, and 22.3% in winter; 45.1% of samples were from male cats and the rest from female ones. Of the studied cats, 118 were younger than 1 year, 78 were 1-3 years old, and 68 were older than 3 years. The specimens were subjected to direct microscopic examination with 15% potassium hydroxide and cultured on Sabouraud dextrose agar and dermatophyte test medium supplemented with cycloheximide and chloramphenicol. Dermatophyte identification was carried out based on macroscopic and microscopic colony morphology, urease activities, in vitro hair perforation test, growth at 37°C, and pigmentation on corn meal agar. Dermatophytes were isolated from 19 (7.1%) of the 264 specimens examined. The most frequently isolated fungi were Trichophyton terrestre (4.1%), followed by Microsporum gypseum (1.1%), M. nanum (1.1%), and T. mentagrophytes (0.7%), and these fungi may represent a health risk for humans in contact with clinically healthy Van cats. M. canis was not isolated from any of the specimens. Our results show no significant (p>0.05) association between carriage of dermatophytes and the gender of cats. The carriage rate of dermatophytes was high in spring and winter, and the only possible risk factor for infection was age of the animal. Copyright © 2015 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Evaluation of five selective media for the detection of Pseudomonas aeruginosa using a strain panel from clinical, environmental and industrial sources.

PubMed

Weiser, Rebecca; Donoghue, Denise; Weightman, Andrew; Mahenthiralingam, Eshwar

2014-04-01

Isolation and correct identification of the opportunistic pathogen and industrial contaminant Pseudomonas aeruginosa are very important and numerous selective media are available for this purpose. A novel comparison of five selective media having positive (acetamide-based agars), negative (Pseudomonas CN selective agar [Oxoid Ltd.] and Pseudomonas Isolation agar [Sigma-Aldrich Company Ltd.]) and chromogenic (chromID® P. aeruginosa [bioMérieux]) selection strategies was performed using a systematically designed bacterial test panel (58 P. aeruginosa and 90 non-P. aeruginosa strains including those commonly misidentified as P. aeruginosa by culture-dependent techniques). Standardised inocula were added to the selective media and the results were recorded after 24 and 72h. After 72h of incubation at 37°C chromID® P. aeruginosa displayed the highest specificity (70%) and had good sensitivity (95%), although the sensitivity was negatively impacted by the large variation in colour of P. aeruginosa colonies, which hampered interpretation. Both media containing inhibitory selective agents performed very similarly, both having 100% sensitivity and a specificity of approximately 30%. Raising the incubation temperature to 42°C increased the specificity of Pseudomonas CN selective agar and Pseudomonas isolation agar (61% and 47% respectively after 72h), but increased the number of false positives encountered with the chromogenic medium, decreasing its specificity to 68% after 72h. Growth on the acetamide agars was weak for all strains and it was often difficult to determine whether true growth had occurred. This, compounded by the low specificity of the acetamide agars (<26%), suggested they were less suitable for application to clinical or industrial settings without further modification. Overall, the chromogenic agar was the most selective but further consideration is required to optimise interpretation of results. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison of chromogenic Biolog Rainbow agar Shigella/Aeromonas with xylose lysine desoxycholate agar for isolation and detection of Shigella spp. from foods.

PubMed

Zhang, Guodong; Lampel, Keith A

2010-08-01

Shigella outbreaks are widely reported throughout the world. However, it remains a challenge to isolate Shigella spp. from foods by using conventional microbiological media. The main objective of this study was to determine the effectiveness of a novel chromogenic medium, Rainbow agar Shigella/Aeromonas (Rainbow agar), for the isolation and detection of Shigella spp. in foods. All four Shigella species, S. sonnei, S. flexneri, S. dysenteriae, and S. boydii, were studied. Rainbow agar was compared with tryptic soy agar, xylose lysine desoxycholate agar (XLD), and Salmonella Shigella agar (SSA) for enumeration of Shigella spp. in pure culture. This chromogenic agar and XLD were also used to isolate Shigella spp. in artificially contaminated foods (4.8 log CFU/g of food), including lettuce, parsley, cilantro, spinach, potato salad, and shrimp. The inhibitory effect on Shigella growth by Rainbow agar was between that of XLD and SSA. All vegetables studied showed a moderately high background microflora on XLD and Rainbow agar. With artificially inoculated produce, Rainbow agar recovered about 1 to 2 log CFU more S. sonnei, S. dysenteriae, and S. boydii per g of food than did XLD. For potato salad and shrimp, which had low background microflora on Rainbow agar, Rainbow agar was slightly better in recovering Shigella spp. than XLD was in most cases. However, we found that the addition of streptomycin (6.25 mg/liter) to Rainbow agar could facilitate the isolation of Shigella in vegetables tested. In conclusion, Rainbow agar was a much more effective medium than was XLD for the isolation of Shigella spp. from foods.

Comparison of seven plating media for enumeration of Listeria spp.

PubMed Central

Loessner, M J; Bell, R H; Jay, J M; Shelef, L A

1988-01-01

The suitability of seven media for the enumeration of Listeria spp. was evaluated at 30 degrees C for 48 h. The media tested were (i) the original McBride Listeria agar formulation (with glycine); (ii) modified McBride agar containing glycine anhydride; (iii) LiCl-phenylethanol-moxalactam (LPM) agar; (iv) acriflavine-ceftazidime agar; (v) Rodriguez isolation agar (RISA); (vi) modified Vogel-Johnson (MVJ) agar; (vii) cyclohexanedione-nalidixic acid-phenylethanol agar; and tryptose agar as control. A total of 66 organisms were used including 11 Listeria monocytogenes strains and 5 other Listeria spp. For L. monocytogenes strains only, all media performed highly similarly. Of the other Listeria spp., only two grew on MVJ agar and three each grew on LPM and RISA. Only LPM agar inhibited the 50 non-listeriae, including five yeasts, while MVJ agar inhibited all but one yeast. The McBride Listeria agar formulation that contained glycine anhydride was less selective than the original. When pure cultures of 10 bacteria (including one L. monocytogenes strain) were combined and plated on four media, L. monocytogenes colonies were easiest to enumerate on MVJ agar, followed by LPM and RISA. These media ranked in the same order when plated with homogenates of various foods to which was added L. monocytogenes Scott A, but LPM agar was the best overall since Scott A was inhibited by MVJ. Upon microscopic examination of listerial colonies from the plating media, atypical cell morphology was noted with cells being about twofold in size on LPM, MVJ, and acriflavine-ceftazidime agars. Overall, LPM agar was the most suitable of the media tested even though it was inhibitory to Listeria grayi and Listeria murrayi. PMID:3146947

Growth of Desulfovibrio on the Surface of Agar Media

PubMed Central

Iverson, Warren P.

1966-01-01

Growth of Desulfovibrio desulfuricans (API strain) was found to take place in an atmosphere of hydrogen on the agar surface of complex media, including yeast extract (Difco), and Trypticase Soy Agar (BBL) without any added reducing agents. For growth on a 2% yeast extract-agar surface in the absence of hydrogen (nitrogen atmosphere), sodium lactate was required in the medium. Growth on the surface of Trypticase Soy Agar (TSA) under nitrogen took place readily in the absence of an added hydrogen donor. A medium (TSA plus salts) is described based upon the addition of sodium lactate (4 ml per liter), magnesium sulfate (2 g per liter), and ferrous ammonium sulfate (0.05%) to TSA, which appears suitable for the isolation and growth of Desulfovibrio on the surface of agar plates in an atmosphere of hydrogen. Sodium lactate does not appear to be essential in this medium for good growth and sulfate reduction in a hydrogen atmosphere, but is essential in a nitrogen atmosphere. Growth of Desulfovibrio (hydrogen atmosphere) on the agar surface of media commonly used for its cultivation as well as on an inorganic medium containing bicarbonate as a source of carbon is poor and erratic unless inoculated (Desulfovibrio) plates of TSA plus salts are incubated in the same container with plates of these media. This stimulatory effect of incubation with inoculated plates of TSA plus salts medium appears to be due to as yet unidentified volatile material produced by D. desulfuricans when growing on this medium. Another volatile material, or possibly the identical material, appears to act similarly to a hydrogen donor. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:5955798

[Investigation on antibacterial activity of Forsythia suspense Vahl in vitro with Mueller-Hinton agar].

PubMed

Li, Z X; Wang, X H; Zhao, J H; Yang, J F; Wang, X

2000-12-01

To evaluate the antibacterial activity of Forsythia suspensa in vitro with different media. MIC determination of Forsythia suspensa against Staphylococci was performed by the agar dilution method. MIC90 of decoction of Forsythia suspensa against Staphylococcus epidermidis in M-H agar was 1:640, but in nutrient agar 1:40, the antibacterial activity with M-H agar being 16 fold higher than nutrient agar. The M-H agar should be recommended to replace nutrient agar as medium in the antibacterial experiment of Traditional Chinese medicine, and it is better to use multipoint inoculating device in the sensitivity test.

Borelli's lactritmel agar induces conidiation in rare-macroconidia producing dermatophytic fungi.

PubMed

Ilkit, Macit; Gümral, Ramazan; Döğen, Aylin

2012-10-01

Macroconidia are among the most important indicators used to identify dermatophytic fungi, but several do not usually sporulate and/or produce macroconidia on Sabouraud glucose agar. Specifically, Microsporum audouinii, M. ferrugineum, Trichophyton concentricum, T. schoenleinii, T. verrucosum, and T. violaceum (including T. soudanense and T. yaoundei) rarely form macroconidia and, therefore, cannot be easily identified. In this study, we investigated the production of macroconidia on nine common laboratory media, including Borelli's lactritmel agar (BLA), modified Borelli's lactritmel agar (MBLA), brain heart infusion agar (BHIA), Christensen's urease agar in Petri dishes (UPA), cornmeal dextrose agar (CMDA), Lowenstein-Jensen agar (LJA), malt extract agar (MEA), oatmeal agar (OA), and potato dextrose agar (PDA). The performance of these media was evaluated using 18 rare-macroconidia producing isolates, including representative of the six species mentioned above. All cultures in this study were incubated at 26°C on the bench, and conidia formation on each was investigated at 5, 10, 15, 20, 25, and 30 days of incubation. BLA apparently improved macroconidia production after 15 days and was the most useful nutrient agar medium to induce these phenotypic characters in daily practice, closely followed by OA, PDA, and MBLA.

Principles of assessing bacterial susceptibility to antibiotics using the agar diffusion method.

PubMed

Bonev, Boyan; Hooper, James; Parisot, Judicaël

2008-06-01

The agar diffusion assay is one method for quantifying the ability of antibiotics to inhibit bacterial growth. Interpretation of results from this assay relies on model-dependent analysis, which is based on the assumption that antibiotics diffuse freely in the solid nutrient medium. In many cases, this assumption may be incorrect, which leads to significant deviations of the predicted behaviour from the experiment and to inaccurate assessment of bacterial susceptibility to antibiotics. We sought a theoretical description of the agar diffusion assay that takes into consideration loss of antibiotic during diffusion and provides higher accuracy of the MIC determined from the assay. We propose a new theoretical framework for analysis of agar diffusion assays. MIC was determined by this technique for a number of antibiotics and analysis was carried out using both the existing free diffusion and the new dissipative diffusion models. A theory for analysis of antibiotic diffusion in solid media is described, in which we consider possible interactions of the test antibiotic with the solid medium or partial antibiotic inactivation during diffusion. This is particularly relevant to the analysis of diffusion of hydrophobic or amphipathic compounds. The model is based on a generalized diffusion equation, which includes the existing theory as a special case and contains an additional, dissipative term. Analysis of agar diffusion experiments using the new model allows significantly more accurate interpretation of experimental results and determination of MICs. The model has more general validity and is applicable to analysis of other dissipative processes, for example to antigen diffusion and to calculations of substrate load in affinity purification.

Micropropagation and cytogenetic assessment of Zingiber species of Northeast India.

PubMed

Das, Archana; Kesari, Vigya; Rangan, Latha

2013-12-01

An improved micropropagation protocol was developed for Zingiber moran and Z. zerumbet, two wild species of the genus Zingiber, found in Northeast India. The effects of growth regulators, sugar concentrations, and nutrients were tested on the rate of shoot initiation and multiplication. An increase in proliferation and multiplication occurred in modified Murashige and Skoog (MS) medium supplemented with benzyladenine and kinetin. About 2 % sucrose and 0.7 % agar were found to be the optimum for shoot multiplication and regeneration. Naphthalene acetic acid at 0.5 mg/L produced the best rooting response for both the species. Regenerated plantlets were acclimatized successfully and cytogenetic stability was confirmed by RAPD profiling and ploidy checks.

Screening of Different Media and Substrates for Cultural Variability and Mass Culture of Arthrobotrys dactyloides Drechsler

PubMed Central

Kumar, D.; Jaiswal, R. K.

2005-01-01

Variability in growth and sporulation of five isolates of Arthrobotrys dactyloides was studied on five agar, 6 bran and 5 grain media. Potato dextrose agar (PDA) supported maximum growth of isolate A, C and E, while growth of isolate B and D was significantly lower on this medium. On Czapek's agar and yeast glucose agar media the differentiation in the isolates in relation to growth was poor than PDA. The other two media showed much poorer differentiation. On Czapek's agar medium, sporulation was recorded in isolate B only, whereas other isolates showed rare sporulation. Among the bran media, pea bran agar medium supported maximum growth of all the isolates except isolate B. Gram and rice bran agar media were next best. However, the growth of isolate B on the gram bran agar medium was more or less equal as other isolates. On pigeon pea bran agar medium, isolate E failed to grow while other isolates recorded poor growth. On lentil bran agar medium, only isolate B and D recorded little growth, whereas other isolates failed to grow. All the isolates recorded good sporulation on bran agar media except pigeon pea and lentil bran agar media. The grain agar media supported moderate to very good growth of all the isolates. In general isolate B remained slow growing on these media except gram grain and sorghum grain agar media on which growth of this isolate was comparable to other isolates. Sporulation in general, was good on all the grain agar media. Among different substrates screened, barley grain and pea bran were found superior to others for mass culture of isolate A of A. dactyloides. PMID:24049504

Screening fungicides for use in fish culture: Evaluation of the agar plug transfer, cellophane transfer, and agar dilution methods

USGS Publications Warehouse

Bailey, Tom A.

1983-01-01

The reliability, reproducibility, and usefulness of three screening methods -- the cellophane transfer, the agar plug transfer, and the agar dilution -- to screen aquatic fungicides were evaluated. Achlya flagellata and Saprolegnia hypogyna were exposed to 1, 10, and 100 mg/L of malachite green to test each method. The cellophane transfer and agar plug transfer techniques had similar reliability and reproducibility in rating fungicidal activity, and were both superior to the agar dilution technique. The agar plug transfer and agar dilution techniques adequately projected in vivo activity of malachite green, but the cellophane transfer technique overestimated its activity. Overall, the agar plug transfer technique most accurately rated the activity of malachite green and was the easiest test to perform. It therefore appears to be the method of choice for testing aquatic fungicides.

Spreading of nonmotile bacteria on a hard agar plate: Comparison between agent-based and stochastic simulations

NASA Astrophysics Data System (ADS)

Rana, Navdeep; Ghosh, Pushpita; Perlekar, Prasad

2017-11-01

We study spreading of a nonmotile bacteria colony on a hard agar plate by using agent-based and continuum models. We show that the spreading dynamics depends on the initial nutrient concentration, the motility, and the inherent demographic noise. Population fluctuations are inherent in an agent-based model, whereas for the continuum model we model them by using a stochastic Langevin equation. We show that the intrinsic population fluctuations coupled with nonlinear diffusivity lead to a transition from a diffusion limited aggregation type of morphology to an Eden-like morphology on decreasing the initial nutrient concentration.

Assessment of formulas for calculating critical concentration by the agar diffusion method.

PubMed Central

Drugeon, H B; Juvin, M E; Caillon, J; Courtieu, A L

1987-01-01

The critical concentration of antibiotic was calculated by using the agar diffusion method with disks containing different charges of antibiotic. It is currently possible to use different calculation formulas (based on Fick's law) devised by Cooper and Woodman (the best known) and by Vesterdal. The results obtained with the formulas were compared with the MIC results (obtained by the agar dilution method). A total of 91 strains and two cephalosporins (cefotaxime and ceftriaxone) were studied. The formula of Cooper and Woodman led to critical concentrations that were higher than the MIC, but concentrations obtained with the Vesterdal formula were closer to the MIC. The critical concentration was independent of method parameters (dilution, for example). PMID:3619419

Multiparametric comparison of chromogenic-based culture methods used to assess the microbiological quality of drinking water and the mFC method combined with a molecular confirmation procedure.

PubMed

Maheux, Andrée F; Dion-Dupont, Vanessa; Bisson, Marc-Antoine; Bouchard, Sébastien; Jubinville, Éric; Nkuranga, Martine; Rodrigue, Lynda; Bergeron, Michel G; Rodriguez, Manuel J

2015-03-01

MI agar and Colilert(®), as well as mFC agar combined with an Escherichia coli-specific molecular assay (mFC + E. coli rtPCR), were compared in terms of their sensitivity, ease of use, time to result and affordability. The three methods yielded a positive E. coli signal for 11.5, 10.8, and 11.5% of the 968 well water samples tested, respectively. One hundred and thirty-six (136) samples gave blue colonies on mFC agar and required confirmation. E. coli-specific rtPCR showed false-positive results in 23.5% (32/136) of cases. In terms of ease of use, Colilert was the simplest method to use while the MI method provided ease of use comparable to all membrane filtration methods. However, the mFC + E. coli rtPCR assay required highly trained employees for confirmation purposes. In terms of affordability, and considering contamination rate of well water samples tested, the Colilert method and the mFC + E. coli rtPCR assay were at least five times more costly than the MI agar method. Overall, compared with the other two methods tested, the MI agar method offers the most advantages to assess drinking water quality.

Development of edible films from tapioca starch and agar, enriched with red cabbage (Brassica oleracea) as a sausage deterioration bio-indicator

NASA Astrophysics Data System (ADS)

Aditya Wardana, Ata; Dewanti Widyaningsih, Tri

2017-12-01

Sausage spoilage has been identified as a cause of some food poisoning cases. Development of a bioindicator film is one of the alternative methods to detect sausage deterioration. The objectives of this paper were to develop a bioindicator edible films (BEF) from tapioca starch (TS), agar, and red cabbage juice (RC), and to evaluate its performance on sausage deterioration detection. The experiment had a 3x3 randomized factorial experimental design (agar: 3, 5, 7% by weight of TS; RC: 10, 15, 20% v/v based on 100% of suspension). Glycerol was used as the plasticizer. The results showed that the addition of agar into the film solution increased the thickness, elongation, and tensile strength, and decreased water vapour transmission rate (WVTR). While the addition of RC increased the thickness, but decreased elongation, tensile strength, and WVTR. BEF consisting of 2% tapioca starch, 7% (w/w) agar and 10 % (v/v) RC was chosen to apply on sausage. It could detect an increase in the microbial population and in the pH variations as result of sausage deterioration at 24, 48, and 72 h shown through color changes of BEF from bright purple at 0 h to light purple, dark purple-blue, and purple-green color respectively.

[Thin layer agar represents a cost-effective alternative for the rapid diagnosis of multi-drug resistant tuberculosis].

PubMed

Hernández-Sarmiento, José M; Martínez-Negrete, Milton A; Castrillón-Velilla, Diana M; Mejía-Espinosa, Sergio A; Mejía-Mesa, Gloria I; Zapata-Fernández, Elsa M; Rojas-Jiménez, Sara; Marín-Castro, Andrés E; Robledo-Restrepo, Jaime A

2014-01-01

Using cost-benefit analysis for comparing the thin-layer agar culture method to the standard multiple proportion method used in diagnosing multidrug-resistant tuberculosis (MDR TB). A cost-benefit evaluation of two diagnostic tests was made at the Corporación para Investigaciones Biológicas (CIB) in Medellín, Colombia. 100 patients were evaluated; 10.8% rifampicin resistance and 14.3% isoniazid resistance were found. A computer-based decision tree model was used for cost-effectiveness analysis (Treeage Pro); the thin-layer agar culture method was most cost-effective, having 100% sensitivity, specificity and predictive values for detecting rifampicin and isoniazid resistance. The multiple proportion method value was calculated as being US$ 71 having an average 49 day report time compared to US$ 18 and 14 days for the thin-layer agar culture method. New technologies have been developed for diagnosing tuberculosis which are apparently faster and more effective; their operating characteristics must be evaluated as must their effectiveness in terms of cost-benefit. The present study established that using thin-layer agar culture was cheaper, equally effective and could provide results more quickly than the traditional method. This implies that a patient could receive MDR TB treatment more quickly.

Rapid Direct Testing of Susceptibility of Mycobacterium tuberculosis to Isoniazid and Rifampin on Nutrient and Blood Agar in Resource-Starved Settings

PubMed Central

Ikram, Aamer; Coban, Ahmet Yilmaz; Martin, Anandi

2012-01-01

In this study, we evaluated the performance of blood agar (by macroscopic growth) and nutrient agar (by a microcolony detection method) for drug susceptibility testing of Mycobacterium tuberculosis against rifampin (RIF) and isoniazid (INH), using 67 smear-positive sputum specimens. The direct proportion method on Lowenstein-Jensen (LJ) medium was used as the “gold standard.” Compared with LJ medium, results for both media were in 100% agreement for RIF, while for INH the agreement levels for blood agar and nutrient agar were 98% and 95%, respectively. Within 2 weeks, 100% of specimens yielded results on blood agar, while 96.8% of specimens yielded results on nutrient agar. Our study showed that blood agar and nutrient agar can be used as alternative media for direct susceptibility testing of RIF and INH, especially in resource-poor settings. PMID:22357498

Rapid direct testing of susceptibility of Mycobacterium tuberculosis to isoniazid and rifampin on nutrient and blood agar in resource-starved settings.

PubMed

Satti, Luqman; Ikram, Aamer; Coban, Ahmet Yilmaz; Martin, Anandi

2012-05-01

In this study, we evaluated the performance of blood agar (by macroscopic growth) and nutrient agar (by a microcolony detection method) for drug susceptibility testing of Mycobacterium tuberculosis against rifampin (RIF) and isoniazid (INH), using 67 smear-positive sputum specimens. The direct proportion method on Lowenstein-Jensen (LJ) medium was used as the "gold standard." Compared with LJ medium, results for both media were in 100% agreement for RIF, while for INH the agreement levels for blood agar and nutrient agar were 98% and 95%, respectively. Within 2 weeks, 100% of specimens yielded results on blood agar, while 96.8% of specimens yielded results on nutrient agar. Our study showed that blood agar and nutrient agar can be used as alternative media for direct susceptibility testing of RIF and INH, especially in resource-poor settings.

Agar Underlay Method for Recovery of Sublethally Heat-Injured Bacteria

PubMed Central

Kang, D. H.; Siragusa, G. R.

1999-01-01

A method of recovering sublethally heat-injured bacteria was developed. The procedure (termed the agar underlay method) uses a nonselective agar underlaid with a selective medium. In a two-chambered petri dish, the Lutri plate (LP), a nonselective agar is inoculated with a population of sublethally heat-injured bacteria. After a 2-h repair incubation period, selective agar is added to the bottom chamber of the LP and incubated. By diffusing through the nonselective top agar, selective agents from the underlay medium impart selectivity to the system. By the agar underlay method, recovery rates of the heat-injured food-borne pathogens Escherichia coli O157:H7 and Salmonella typhimurium were not different (P > 0.05) from recovery rates determined with nonselective media. Sublethally heat-injured cells (60°C for 1.5 min in buffer or 80°C for 30 s on meat surfaces) grew and produced a typical colony morphology and color reaction when the agar underlay procedure was used with the appropriate respective selective agars. Unlike agar overlay methods for injury repair, the agar underlay procedure allows the typical selective-medium colony morphology to develop and allows colonies to be more easily picked for further characterization. Higher recovery rates of heat-injured fecal enterococci from bovine fecal samples and total coliforms from animal waste lagoons were obtained by the agar underlay method with selective agars than by direct plating on the respective selective media. PMID:10583985

Evaluation of Bacillus spp. as dough starters for Adhirasam - A traditional rice based fermented food of Southern India.

PubMed

Anisha, Anvar Hussain Noorul; Anandham, Rangasamy; Kwon, Soon Woo; Gandhi, Pandiyan Indira; Gopal, Nellaiappan Olaganathan

2015-01-01

Adhirasam is a cereal based, doughnut shaped, deep fried dessert consumed in the southern regions of India. The dough used to prepare adhirasam is fermented and contains rice flour and jaggery. The aim of the present study was to characterize the cultivable bacteria associated with this fermented dough and to identify a suitable starter culture for the production of quality adhirasam. In total, one hundred and seventy bacterial isolates were recovered from de Man Rogosa Sharp (MRS) agar, nutrient agar, lysogeny agar and tryptic soy agar media. Out of the 170 bacterial isolates, sixteen isolates were selected based on their ability to tolerate glucose and sucrose. All the bacterial isolates tolerated 15% glucose and 30% sucrose. Analyses of 16S rDNA gene sequences of the bacterial isolates showed that the dominant cultivable bacteria were members of the genus Bacillus. These strains were further used as starters and tested for their ability to ferment rice flour with jaggery to produce adhirasam dough. Organoleptic evaluation was carried out to choose the best starter strain. Adhirasam prepared from Bacillus subtilis isolates S4-P11, S2-G2-A1 and S1-G15, Bacillus tequilensis isolates S2-H16, S3-P9, S3-G10 and Bacillus siamensis isolate S2-G13 were highly acceptable to consumers. Adhirasam prepared using these starter cultures had superior product characteristics such as softness in texture, flavor and enhanced aroma and sweet taste.

Comparison of MI, Chromocult® coliform, and Compass CC chromogenic culture-based methods to detect Escherichia coli and total coliforms in water using 16S rRNA sequencing for colony identification.

PubMed

Maheux, Andrée F; Bouchard, Sébastien; Bérubé, Ève; Bergeron, Michel G

2017-06-01

The MI, Chromocult ® coliform, and Compass CC chromogenic culture-based methods used to assess water quality by the detection of Escherichia coli and total coliforms were compared in terms of their specificity and sensitivity, using 16S rRNA sequencing for colony identification. A sewage water sample was divided in 2-μL subsamples for testing by all three culture-based methods. All growing colonies were harvested and subjected to 16S rRNA sequencing. Test results showed that all E. coli colonies were correctly identified by all three methods, for a specificity and a sensitivity of 100%. However, for the total coliform detection, the MI agar, Chromocult ® coliform agar, and Compass CC agar were specific for only 69.2% (9/13), 47.2% (25/53), and 40.5% (17/42), whereas sensitive for 97.8% (45/46), 97.5% (39/40), and 85.7% (24/28), respectively. Thus, given the low level of specificity of these methods for the detection of total coliforms, confirming the identity of total coliform colonies could help to take public health decisions, in particular for cities connected to a public drinking water distribution system since the growth of few putative total coliform colonies on chromogenic agar is problematic and can lead to unnecessary and costly boiling notices from public health authorities.

Colonization of Legionella species in Turkish baths in hotels in Alanya, Turkey.

PubMed

Erdogan, Haluk; Arslan, Hande

2015-05-01

This study evaluated the prevalence of Legionella species in water samples collected from Turkish baths in hotels in Alanya, Turkey, from August 2003 to September 2013. Water samples were collected in 100-mL sterile containers and then concentrated by filtration. Heat treatment was used to eliminate other microorganisms from the samples, which were then spread on Legionella-selective-buffered charcoal yeast extract alpha (BCYE-α) agar and on BCYE-α agar supplemented with glycine, vancomycin, polymyxin, and cycloheximide. Cysteine-dependent colonies were identified by latex agglutination. In total, 135 samples from 52 hotels with Turkish baths were evaluated. Legionella species were identified in 11/52 (21.2%) hotels and 18/135 (13.3%) samples. The most frequently isolated species was Legionella pneumophila, with most isolates belonging to serogroups 6 (55.6%) and 1 (22.2%). The colony count was <100 colony-forming units (CFU) mL(-1) in nine samples, from 100 to 1000 CFU mL(-1) in six samples, and >1000 CFU mL(-1) in three samples. These findings suggest that the hot water systems of Turkish baths in hotels must be viewed as a possible source of travel-associated Legionnaires' disease, and preventative measures should be put in place.

Pathogenic and enzyme activities of the entomopathogenic fungus Tolypocladium cylindrosporum (Ascomycota: Hypocreales) from Tierra del Fuego, Argentina.

PubMed

Scorsetti, Ana C; Elíades, Lorena A; Stenglein, Sebastián A; Cabello, Marta N; Pelizza, Sebastián A; Saparrat, Mario C N

2012-06-01

Tolypocladium cylindrosporum is an entomopathogenic fungi that has been studied as a biological control agent against insects of several orders. The fungus has been isolated from the soil as well as from insects of the orders Coleoptera, Lepidoptera, Diptera and Hymenoptera. In this study, we analyzed the ability of a strain of T cylindrosporum, isolated from soil samples taken in Tierra del Fuego, Argentina, to produce hydrolytic enzymes, and to study the relationship of those activities to the fungus pathogenicity against pest aphids. We have made the traditional and molecular characterization of this strain of T cylindrosporum. The expression of hydrolase activity in the fungal strain was estimated at three incubation temperatures (4 degreeC, 12 degreeC and 24 degreeC), on different agar media supplemented with the following specific substrates: chitin azure, Tween 20, casein, and urea for chitinase, lipase, protease, and urease activity, respectively. The hydrolytic-enzyme activity was estimated qualitatively according to the presence of a halo of clarification through hydrolase action, besides was expressed semi-quantitatively as the ratio between the hydrolytic-halo and colony diameters. The pathogenicity of the fungus was tested on adults of the aphid Rhopalosiphum padi at three temperatures of incubation (4 degree C, 12 degree C and 24 degree C). The suspension was adjusted to a concentration of 1x10(7) conidia/ml. In pathogenicity assays at seven days post-inoculation, the fungus caused the mortality of adults of Ropalosiphum padi at different temperatures also showed a broad ability to grow on several agar-culture media, supplemented with different carbon sources at the three incubation temperatures tested. Although, the growth was greater with higher incubation temperatures (with maximum levels at 24 degreeC), the fungus reached similar colony diameters after 15 days of incubation on the medium supplemented with Tween 20 at the lower two incubation temperatures of 4 degreeC or 12 degreeC. In accordance with the results on colony diameters, the fungus revealed an ability to degrade casein, chitin derivatives, Tween 20, and urea as evidenced by the appearance of a halo around the fungal colony. Because of its origin and temperature tolerance, this Argentine strain has great potential for use as a biocontrol agent for insect pest control in cold and temperate environments.

Agar dilution and agar screen with cefoxitin and oxacillin: what is known and what is unknown in detection of meticillin-resistant Staphylococcus aureus.

PubMed

Perez, Leandro Reus Rodrigues; Dias, Cícero; d'Azevedo, Pedro Alves

2008-08-01

In this study we evaluated the performance of the oxacillin agar screen test, and agar dilution tests using cefoxitin and oxacillin antimicrobials, to detect meticillin resistance in Staphylococcus aureus isolates. The presence of the mecA gene, detected by PCR, was used as the standard to which agar screen and agar dilution tests were compared. The best performance was obtained using the agar dilution test (99.4 % accuracy) with breakpoints of 4 mug ml(-1) for oxacillin and 8 mug ml(-1) for cefoxitin, and using the oxacillin agar screen test. Also, a strong correlation between MIC values of cefoxitin and oxacillin permits the use of either drug for detection of meticillin resistance.

A Novel Chromogenic Ester Agar Medium for Detection of Salmonellae

PubMed Central

Cooke, Venitia M.; Miles, R. J.; Price, R. G.; Richardson, A. C.

1999-01-01

A novel agar medium, chromogenic Salmonella esterase (CSE) agar, for the differentiation of salmonellae is described. The agar contains peptones and nutrient extracts together with the following (grams per liter unless otherwise specified): 4-[2-(4-octanoyloxy-3,5-dimethoxyphenyl)-vinyl]-quinolinium-1-(propan-3-yl carboxylic acid) bromide (SLPA-octanoate; bromide form), 0.3223; lactose, 14.65; trisodium citrate dihydrate, 0.5; Tween 20, 3.0; ethyl 4-dimethylaminobenzoate, 0.035% (wt/vol), novobiocin, 70 mg liter−1. The key component of the medium is SLPA-octanoate, a newly synthesized ester formed from a C8 fatty acid and a phenolic chromophore. In CSE agar, the ester is hydrolyzed by Salmonella spp. to yield a brightly colored phenol which remains tightly bound within colonies. After 24 h of incubation at 37 or 42°C, colonies of typical Salmonella spp. were burgundy colored on a transparent yellow background, whereas non-Salmonella spp. were white, cream, yellow or transparent. CSE agar was evaluated by using a panel of strains including a high proportion of Salmonella and non-Salmonella strains giving atypical reactions on other differential agars. The sensitivity (93.1%) of CSE agar for non-typhi salmonellae compared favorably with those of Rambach (82.8%), xylose-lysine-deoxycholate (XLD; 91.4%), Hektoen-enteric (89.7%), and SM ID (91.4%) agars. The specificity (93.9%) was also comparable to those of other Salmonella media (SM ID agar, 95.9%; Rambach agar, 91.8%; XLD agar, 91.8%; Hektoen-enteric agar, 87.8%). Strains of Citrobacter freundii and Proteus spp. giving false-positive reactions with other media gave a negative color reaction on CSE agar. CSE agar enabled the detection of >30 Salmonella serotypes, including agona, anatum, enteritidis, hadar, heidelberg, infantis, montevideo, thompson, typhimurium, and virchow, which accounted for 91.8% of the salmonella isolates recorded by the Public Health Laboratory Service (Colindale, London, England) for 1997. PMID:9925620

Structural, morphological, optical and biological properties of pure ZnO and agar/zinc oxide nanocomposites.

PubMed

Magesh, G; Bhoopathi, G; Nithya, N; Arun, A P; Ranjith Kumar, E

2018-05-26

In this work, ZnO nanoparticles were prepared by in situ chemical precipitation method in the presence of Agar biopolymer. The influence of Agar concentrations on the structural, morphological and optical properties of ZnO have been investigated. The XRD pattern of Pure ZnO and Agar/ZnO nanocomposites indicates the hexagonal wurtzite phase of ZnO. The crystallite size of pure ZnO and Agar/ZnO nanocomposites was found to be in the range of 35.5 to 19.73 nm. Pure ZnO and Agar/ZnO nanocomposites showed nanospheroid and nanopaddy shaped morphology from FESEM studies. The interplanar distance observed from the HRTEM image confirms the plane of the prepared material. The elemental composition of the samples were characterized by EDX. The optical properties of Pure ZnO and Agar/ZnO nanocomposites were characterized by UV, FTIR and PL. The band gap of Agar/ZnO nanocomposites were varied with the Agar concentration. Oxygen vacancy induced photoluminescence of ZnO are observed and its intensity is found to be increased linearly with the Agar concentration. The antibacterial activity of ZnO and Agar/ZnO nanocomposites was evaluated by disc diffusion method against Gram-positive (B.subtilis) and Gram-negative (P. aeruginosa) bacteria. The cytotoxicity of Agar/ZnO nanocomposites was studied against Normal (L929) and Breast cancer cell line (MB231). The result of this investigation reveals that the Agar/ZnO nanocomposites deliver a dose dependent toxicity in normal and cancer cell line. Copyright © 2018. Published by Elsevier B.V.

Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam.

PubMed

Trung, Nguyen Vinh; Nhung, Hoang Ngoc; Carrique-Mas, Juan J; Mai, Ho Huynh; Tuyen, Ha Thanh; Campbell, James; Nhung, Nguyen Thi; Van Minh, Pham; Wagenaar, Jaap A; Mai, Nguyen Thi Nhu; Hieu, Thai Quoc; Schultsz, Constance; Hoa, Ngo Thi

2016-09-09

Enteroaggregative (EAEC) and Shiga-toxin producing Escherichia coli (STEC) are a major cause of diarrhea worldwide. E. coli carrying both virulence factors characteristic for EAEC and STEC and producing extended-spectrum beta-lactamase caused severe and protracted disease during an outbreak of E. coli O104:H4 in Europe in 2011. We assessed the opportunities for E. coli carrying the aggR and stx genes to emerge in 'backyard' farms in south-east Asia. Faecal samples collected from 204 chicken farms; 204 farmers and 306 age- and gender-matched individuals not exposed to poultry farming were plated on MacConkey agar plates with and without antimicrobials being supplemented. Sweep samples obtained from MacConkey agar plates without supplemented antimicrobials were screened by multiplex PCR for the detection of the stx1, stx2 and aggR genes. One chicken farm sample each (0.5 %) contained the stx1 and the aggR gene. Eleven (2.4 %) human faecal samples contained the stx1 gene, 2 samples (0.4 %) contained stx2 gene, and 31 (6.8 %) contained the aggR gene. From 46 PCR-positive samples, 205 E. coli isolates were tested for the presence of stx1, stx2, aggR, wzx O104 and fliC H4 genes. None of the isolates simultaneously contained the four genetic markers associated with E. coli O104:H4 epidemic strain (aggR, stx2, wzx O104 and fliC H4 ). Of 34 EAEC, 64.7 % were resistant to 3(rd)-generation cephalosporins. These results indicate that in southern Vietnam, the human population is a more likely reservoir of aggR and stx gene carrying E. coli than the chicken population. However, conditions for transmission of isolates and/or genes between human and animal reservoirs resulting in the emergence of highly virulent E. coli strains are still favorable, given the nature of'backyard' farms in Vietnam.

Detection of amphotericin B resistance in Candida haemulonii and closely related species by use of the Etest, Vitek-2 yeast susceptibility system, and CLSI and EUCAST broth microdilution methods.

PubMed

Shin, Jong Hee; Kim, Mi-Na; Jang, Sook Jin; Ju, Min Young; Kim, Soo Hyun; Shin, Myung Geun; Suh, Soon Pal; Ryang, Dong Wook

2012-06-01

The emerging fungal pathogens Candida haemulonii and Candida pseudohaemulonii often show high-level resistance to amphotericin B (AMB). We compared the utilities of five antifungal susceptibility testing methods, i.e., the Etest using Mueller-Hinton agar supplemented with glucose and methylene blue (Etest-MH), the Etest using RPMI agar supplemented with glucose (Etest-RPG), the Vitek-2 yeast susceptibility system, and the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution methods, for the detection of AMB-resistant isolates of C. haemulonii and closely related species. Thirty-eight clinical isolates (8 C. haemulonii, 10 C. pseudohaemulonii, and 20 Candida auris isolates) were analyzed. Of the 18 C. haemulonii and C. pseudohaemulonii isolates, 18, 15, 18, 10, and 9 exhibited AMB MICs of >1 μg/ml by the Etest-MH, Etest-RPG, Vitek-2, CLSI, and EUCAST methods, respectively. All 20 C. auris isolates showed AMB MICs of ≤1 μg/ml by all five methods. Of the methods, the Etest-MH generated the broadest distribution of AMB MICs for all 38 isolates and showed the best discrimination between the C. haemulonii and C. pseudohaemulonii isolates (4 to 32 μg/ml) and those of C. auris (0.125 to 0.5 μg/ml). Taking the Etest-MH as the reference method, the essential agreements (within two dilutions) for the Etest-RPG, Vitek-2, CLSI, and EUCAST methods were 84, 92, 55, and 55%, respectively; the categorical agreements were 92, 92, 79, and 76%, respectively. This study provides the first data on the efficacy of the Etest-MH and its excellent agreement with Vitek-2 for discriminating AMB-resistant from AMB-susceptible isolates of these Candida species.

Effect of the fungus Pochonia chlamydosporia on Echinostoma paraensei (Trematoda: Echinostomatidae).

PubMed

Lelis, Rosane Teixeira; Braga, Fabio Ribeiro; de Carvalho, Lorendane Millena; de Paula, Alessandra Teixeira; Araujo, Juliana Milani; Fausto, Mariana Costa; Junior, Arnaldo Maldonado; Rodrigues, João Victor Facchini; de Freitas Soares, Filippe Elias; Garcia, Juberlan Silva; de Araújo, Jackson Victor

2014-11-01

Echinostoma paraensei is a trematode of the genus Echinostoma that causes echinostomiasis in humans. The objectives of this study were to: evaluate the ovicidal activity of the nematophagous fungus Pochonia chlamydosporia (VC1 and VC4) on a solid medium 2% water-agar (2% WA) against E. paraensei eggs (assay A); evaluate ovicidal effect (destruction of eggs) of the isolate VC4 in supplemented culture media (assay B); and evaluate the ovicidal ability of the crude extract (VC4) on E. paraensei eggs (assay C). Eggs of E. paraensei (assay A) were placed in Petri dishes containing 2% WA with an isolate of the fungus P. chlamydosporia (VC1 and VC4) grown for 10 days, and without fungus as a control and evaluated regarding their destruction. In assay B, eggs of E. paraensei were placed in Petri dishes with different supplemented culture media and with VC4 isolate and the destruction of eggs was examined at the end of 25 days of interaction. In assay C, effects of the crude extract of P. chlamydosporia (VC4) on eggs were evaluated at the end of 7 days. In assay A, there was no difference (p>0.05) in ovicidal activity among the tested isolates (VC1 and VC4); however, the highest percentage for ovicidal activity (type 3 effect) was demonstrated by the isolate VC4. In assay B, the culture medium starch-agar showed the best results for the destruction of the eggs, with a percentage of 46.6% at the end of the assay. In assay C, the crude extract of VC4 was effective in the destruction of E. paraensei eggs, with a percentage reduction of 53%. The results of this study demonstrate that a rich culture medium with a greater availability of carbon and nitrogen may interfere directly in the predatory characteristics of ovicidal fungi. Copyright © 2014 Elsevier B.V. All rights reserved.

Enumeration of the contaminating bacterial microbiota in unfermented pasteurized milks enriched with probiotic bacteria.

PubMed

Champagne, C P; Raymond, Y; Gonthier, J; Audet, P

2009-04-01

Pasteurized and unfermented milks supplemented with probiotic bacteria are appearing on the market. It then becomes a challenge to ascertain the undesirable contamination microbiota in the presence of a largely superior population of probiotic bacteria. A method to enumerate the contaminating microbial microbiota in such probiotic-enriched milks was developed. The probiotic cultures, Lactobacillus rhamnosus Lb-Immuni-T and Bifidobacterium animalis subsp. lactis BB-12(R), were added to a pasteurized unfermented milk to reach a minimum of 1 billion CFU per 250 mL portion, as ascertained by plating on de Man - Rogosa - Sharpe (MRS) agar in anaerobic conditions. No growth of B. animalis subsp. lactis BB-12 was noted on plate count agar (PCA) or Petrifilm plates, and the presence of this culture did not affect standard plate counts (SPC) of contaminating bacteria. However, L. rhamnosus formed colonies on PCA and Petrifilm plates. Attempts were thus made to inhibit the growth of the probiotic lactobacilli in PCA. The addition of 2% sodium phosphate (SP) or 5% glycerophosphate (GP) inhibited the growth of the lactobacilli in broths, but pin-point colonies of L. rhamnosus Lb-Immuni-T nevertheless appeared on PCA supplemented with phosphates. SPC could be obtained on PCA + 2% SP by only counting the large colonies, but this resulted in a significant (4.4 fold) underestimation of SPC values. On Petrifilm AC, at dilutions 0 to 2, all colonies were considered as being contaminants, while at dilutions 3 and 4, only large colonies were counted for SPC determinations. There was a direct correlation (R2 = 0.99) between SPC values with Petrifilm in uninoculated milks and those obtained on probiotic-enriched milks. The high correlation obtained over the 102 to 106 CFU/mL range of SPC values show that this Petrifilm method is appropriate to evaluate the microbiological quality of pasteurized milks enriched with L. rhamnosus Lb-Immuni-T and B. animalis subsp. lactis BB-12.

Diverse bacteria isolated from microtherm oil-production water.

PubMed

Sun, Ji-Quan; Xu, Lian; Zhang, Zhao; Li, Yan; Tang, Yue-Qin; Wu, Xiao-Lei

2014-02-01

In total, 435 pure bacterial strains were isolated from microtherm oil-production water from the Karamay Oilfield, Xinjiang, China, by using four media: oil-production water medium (Cai medium), oil-production water supplemented with mineral salt medium (CW medium), oil-production water supplemented with yeast extract medium (CY medium), and blood agar medium (X medium). The bacterial isolates were affiliated with 61 phylogenetic groups that belong to 32 genera in the phyla Actinobacteria, Firmicutes, and Proteobacteria. Except for the Rhizobium, Dietzia, and Pseudomonas strains that were isolated using all the four media, using different media led to the isolation of bacteria with different functions. Similarly, nonheme diiron alkane monooxygenase genes (alkB/alkM) also clustered according to the isolation medium. Among the bacterial strains, more than 24 % of the isolates could use n-hexadecane as the sole carbon source for growth. For the first time, the alkane-degrading ability and alkB/alkM were detected in Rhizobium, Rhodobacter, Trichococcus, Micrococcus, Enterococcus, and Bavariicoccus strains, and the alkM gene was detected in Firmicutes strains.

Back to the kitchen: food-grade agar is a low-cost alternative to bacteriological agar.

PubMed

Petrovski, Steve; Tillett, Daniel

2012-10-15

Food-grade agar can be used as a low-cost substitute for bacteriological agar in the preparation of solid microbial media. No difference was observed in the colony morphology, growth rate, or viability of bacteria grown on solid media prepared using food-grade agar as compared with using bacteriological-grade agar. This simple tip can reduce the cost of the most common solid media by 80% or more. Copyright © 2012 Elsevier Inc. All rights reserved.

Synthesis and characterization of high-surface-area millimeter-sized silica beads with hierarchical multi-modal pore structure by the addition of agar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Yosep; Choi, Junhyun; Tong, Meiping, E-mail: tongmeiping@iee.pku.edu.cn

2014-04-01

Millimeter-sized spherical silica foams (SSFs) with hierarchical multi-modal pore structure featuring high specific surface area and ordered mesoporous frameworks were successfully prepared using aqueous agar addition, foaming and drop-in-oil processes. The pore-related properties of the prepared spherical silica (SSs) and SSFs were systematically characterized by field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), small-angle X-ray diffraction (SAXRD), Hg intrusion porosimetry, and N{sub 2} adsorption–desorption isotherm measurements. Improvements in the BET surface area and total pore volume were observed at 504 m{sup 2} g{sup −1} and 5.45 cm{sup 3} g{sup −1}, respectively, after an agar addition and foaming process. Despitemore » the increase in the BET surface area, the mesopore wall thickness and the pore size of the mesopores generated from the block copolymer with agar addition were unchanged based on the SAXRD, TEM, and BJH methods. The SSFs prepared in the present study were confirmed to have improved BET surface area and micropore volume through the agar loading, and to exhibit interconnected 3-dimensional network macropore structure leading to the enhancement of total porosity and BET surface area via the foaming process. - Highlights: • Millimeter-sized spherical silica foams (SSFs) are successfully prepared. • SSFs exhibit high BET surface area and ordered hierarchical pore structure. • Agar addition improves BET surface area and micropore volume of SSFs. • Foaming process generates interconnected 3-D network macropore structure of SSFs.« less

Shiga toxin-producing Escherichia coli: a single-center, 11-year pediatric experience.

PubMed

Schindler, Emily I; Sellenriek, Patricia; Storch, Gregory A; Tarr, Phillip I; Burnham, Carey-Ann D

2014-10-01

The aim of this study was to identify the best practices for the detection of Shiga toxin-producing Escherichia coli (STEC) in children with diarrheal illness treated at a tertiary care center, i.e., sorbitol-MacConkey (SMAC) agar culture, enzyme immunoassay (EIA) for Shiga toxin, or the simultaneous use of both methods. STEC was detected in 100 of 14,997 stool specimens submitted for enteric culture (0.7%), with 65 cases of E. coli O157. Among E. coli O157 isolates, 57 (88%) were identified by both SMAC agar culture and EIA, 6 (9%) by SMAC agar culture alone, and 2 (3%) by EIA alone. Of the 62 individuals with diarrheal hemolytic uremic syndrome (HUS) seen at our institution during the study period, 16 (26%) had STEC isolated from cultures at our institution and 15 (24%) had STEC isolated at other institutions. No STEC was recovered in 31 cases (50%). Of the HUS cases in which STEC was isolated, 28 (90%) were attributable to E. coli O157 and 3 (10%) were attributable to non-O157 STEC. Consistent with previous studies, we have determined that a subset of E. coli O157 infections will not be detected if an agar-based method is excluded from the enteric culture workup; this has both clinical and public health implications. The best practice would be concomitant use of an agar-based method and a Shiga toxin EIA, but a Shiga toxin EIA should not be considered to be an adequate stand-alone test for detection of E. coli O157 in clinical samples. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Comparative evaluation of three chromogenic media combined with broth enrichment and the real-time PCR-based Xpert MRSA assay for screening of methicillin-resistant Staphylococcus aureus in nasal swabs.

PubMed

Lee, Seungok; Park, Yeon-Joon; Park, Kang-Gyun; Jekarl, Dong Wook; Chae, Hyojin; Yoo, Jin-Kyung; Seo, Sin Won; Choi, Jung Eun; Lim, Jung Hye; Heo, Seon Mi; Seo, Ju Hee

2013-07-01

We evaluated the performance of three chromogenic media (Brilliance agar I [Oxoid, UK], Brilliance agar II [Oxoid], and ChromID MRSA [Biomérieux, France]) combined with broth enrichment and the Xpert MRSA assay for screening of methicillin-resistant Staphylococcus aureus (MRSA). We obtained 401 pairs of duplicate nasal swabs from 321 patients. One swab was suspended overnight in tryptic soy broth; 50-µL aliquots of suspension were inoculated on the three chromogenic media. Brilliance agar I and II were examined after 24 hr, and ChromID MRSA, after 24 and 48 hr. The paired swab was processed directly using real-time PCR-based Xpert MRSA assay. True positives, designated as MRSA growth in any of the culture media, were detected with the prevalence of 17% in our institution. We report the sensitivity, specificity, positive predictive value, and negative predictive value of MRSA growth as follows: 92.3%, 94.0%, 75.9%, and 98.4% in Brilliance agar I (24 hr); 92.7%, 97.9%, 90.0%, and 98.5% in Brilliance agar II (24 hr); 95.6%, 95.8%, 82.3%, and 99.1% in ChromID MRSA (24 hr); 100%, 92.5%, 73.1%, and 100% in ChromID MRSA (48 hr); 92.6%, 96.7%, 85.1%, and 98.5% in Xpert MRSA assay. The agreement between the enriched culture and Xpert MRSA assay was 96.0%. Three chromogenic culture media combined with enrichment and Xpert MRSA assay demonstrated similar capabilities in MRSA detection. The Xpert MRSA assay yielded results comparable to those of culture methods, saving 48-72 hr, thus facilitating earlier detection of MRSA in healthcare settings.

Soft agar-based selection of spontaneously transformed rat prostate epithelial cells with highly tumorigenic characteristics.

PubMed

Gajdošik, Martina Šrajer; Hixson, Douglas C; Brilliant, Kate E; Yang, DongQin; De Paepe, Monique E; Josić, Djuro; Mills, David R

2018-05-29

The critical molecular and cellular mechanisms involved in the development and progression of prostate cancer remain elusive. In this report, we demonstrate that normal rat prostate epithelial cells (PEC) undergo spontaneous transformation at high passage (p > 85) evidenced by the acquisition of anchorage independent growth when plated on soft agar and tumorigenicity when injected into immunodeficient mice. In addition, we also report the discovery of a minor subpopulation of spontaneously transformed PEC derived from high passage PEC with the ability to migrate through a layer of 1% agar and form expanding colonies on the underlying plastic substratum. Comparison of these soft agar invasive (SAI) cells with low (p < 35), mid (p36-84) and high passage (p > 85) PEC identified marked differences in cell morphology, proliferation and motility. The SAI subpopulation was more tumorigenic than the high passage anchorage independent cultures from which they were isolated, as manifested by a decreased latency period and an increase in the size of tumors arising in immunodeficient mice. In contrast, low and mid passage cells were unable to grow on soft agar and failed to form tumors when injected into immunodeficient mice. Screening with antibody-based signaling arrays identified several differences in the altered expression levels of signaling proteins between SAI-derived cells and low or high passage PEC, including the up-regulation of EGFR and MAPK-related signaling pathways in SAI-selected cells. In summary, these studies suggest that the SAI assay selects for a novel, highly tumorigenic subpopulation of transformed cells that may represent an early step in the progression of slow growing prostatic carcinomas into more rapidly growing and aggressive tumors. Copyright © 2017. Published by Elsevier Inc.

Antimicrobial Susceptibility of Campylobacter Cuniculorum Isolated from Rabbits Reared in Intensive and Rural Farms

PubMed Central

Piva, Silvia; Florio, Daniela; Mion, Domenico; Zanoni, Renato Giulio

2016-01-01

The present study aimed to investigate the antimicrobial susceptibility in Campylobacter cuniculorum. To do so, 29 isolates from rabbits reared in 18 intensive and 11 rural farms not epidemiologically correlated were tested. Minimum inhibitory concentration of 8 antimicrobial agents was determined using the agar dilution method recommended by the Clinical and Laboratory Standards Institute (Wayne, PA, USA), modified – for what supplements in the base medium and incubation conditions concern – for C. cuniculorum isolates. The isolates obtained from rural farming resulted susceptible to all the antimicrobial agents tested, with the exception of one isolate resistant to nalidixic acid. All the isolates obtained from intensively farmed rabbits were sensitive to chloramphenicol and ampicillin; 16 isolates were resistant to tetracycline; 15 to nalidixic acid and erythromycin; 13 and 10 isolates to ciprofloxacin and enrofloxacin, respectively; and only 1 to gentamicin. The resistance of several isolates to macrolides and fluoroquinolones, which are the drugs of choice in treatment of human campylobacteriosis, could pose a risk to human health if a pathogenic role of C. cuniculorum was demonstrated. PMID:27853713

Comparison of media for detection of fungi on spacecraft

NASA Technical Reports Server (NTRS)

Herring, C. M.; Brandsberg, J. W.; Oxborrow, G. S.; Puleo, J. R.

1974-01-01

Five media, including Trypticase soy agar (TSA; BBL) pour plates, spread plates of TSA, Mycophil agar with chloromycetin, Mycophil agar with chloromycetin and Actidione, and cornmeal agar with chloromycetin were quantitatively and qualitatively compared for the detection of fungi on spacecraft. Cornmeal agar with chloromycetin yielded the highest number of fungal colonies, although not always significantly higher than Mycophil agar with chloromycetin or TSA spread plates. Cornmeal agar with chloromycetin also gave the best qualitative representation of fungi on the spacecraft, recovering 68% of the genera found from all media. This medium yielded 10 times the number of fungal colonies and 3 times the number of genera found on TSA pour plates as currently used for spacecraft assay.

Comparison of media for detection of fungi on spacecraft.

PubMed

Herring, C M; Brandsberg, J W; Oxborrow, G S; Puleo, J R

1974-03-01

Five media, including Trypticase soy agar (TSA; BBL) pour plates, spread plates of TSA, Mycophil agar with chloromycetin, Mycophil agar with chloromycetin and Actidione, and cornmeal agar with chloromycetin were quantitatively and qualitatively compared for the detection of fungi on spacecraft. Cornmeal agar with chloromycetin yielded the highest number of fungal colonies, although not always significantly higher than Mycophil agar with chloromycetin or TSA spread plates. Cornmeal agar with chloromycetin also gave the best qualitative representation of fungi on the spacecraft, recovering 68% of the genera found from all media. This medium yielded 10 times the number of fungal colonies and 3 times the number of genera found on TSA pour plates as currently used for spacecraft assay.

Identification of bacteria causing acute otitis media using Raman microspectroscopy

NASA Astrophysics Data System (ADS)

Ayala, Oscar D.; Wakeman, Catherine A.; Skaar, Eric P.; Mahadevan-Jansen, Anita

2016-03-01

Otitis media (OM) is the leading cause of acute physician visits and prescription of antibiotics for children. Current standard techniques to diagnose acute otitis media (AOM) are limited by their ability to probe only changes in symptoms of the bacterial infection that cause AOM. Furthermore, they are not able to detect the presence of or identify bacteria causing AOM, which is important for diagnosis and proper antibiotic treatment. Our goal is to detect the presence of and identify the pathogens involved in causing AOM based on their biochemical profile using Raman spectroscopy (RS). An inVia confocal Raman microscope (Renishaw) at 785 nm was used to detect bacteria causing AOM in vitro. The three main bacteria that cause AOM, Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae were cultured in chocolate agar and Mueller-Hinton agar to determine which agar type would minimize Raman signal from the growth agar. Preliminary results identified specific Raman spectral features characteristic of S. pneumoniae. RS has the potential to accurately diagnose AOM, which will help in identifying the antibiotic that will be most beneficial for the patient and ultimately decrease the course of infection.

A modified MacConkey agar for selective enumeration of necrotoxigenic E. coli O55 and probiotic E. coli Nissle 1917.

PubMed

Splichalova, Alla; Splichal, Igor; Sonnenborn, Ulrich; Rada, Vojtech

2014-09-01

An agar selective enumeration of necrotoxigenic Escherichia coli O55 (NTEC2) and probiotic E. coli Nissle 1917, using modified MacConkey agar, was developed to study bacterial interference between these E. coli strains in a gnotobiotic piglet model. Replacement of lactose with saccharose in the agar enables the direct visual enumeration of red colonies of E. coli O55 and yellow colonies of E. coli Nissle 1917 that are co-cultured in the same Petri dish. A total of 336 colonies (168 for each color) were subjected to strain-specific PCR identification with LNA probes. Sensitivity, specificity, and positive and negative predictive values were 96.43%, 95.83%, 95.86% and 96.41% respectively in E. coli O55, and 98.21%, 97.02%, 97.06% and 98.19% respectively in E. coli Nissle 1917. Color-based enumeration of both E. coli strains in colonic contents and mesenteric lymph nodes homogenates of gnotobiotic piglets demonstrated the applicability of this method for the gnotobiotic piglet model of enteric diseases. Copyright © 2014 Elsevier B.V. All rights reserved.

Simulation of Bacillus subtilis biofilm growth on agar plate by diffusion-reaction based continuum model

NASA Astrophysics Data System (ADS)

Zhang, Xianlong; Wang, Xiaoling; Nie, Kai; Li, Mingpeng; Sun, Qingping

2016-08-01

Various species of bacteria form highly organized spatially-structured aggregates known as biofilms. To understand how microenvironments impact biofilm growth dynamics, we propose a diffusion-reaction continuum model to simulate the formation of Bacillus subtilis biofilm on an agar plate. The extended finite element method combined with level set method are employed to perform the simulation, numerical results show the quantitative relationship between colony morphologies and nutrient depletion over time. Considering that the production of polysaccharide in wild-type cells may enhance biofilm spreading on the agar plate, we inoculate mutant colony incapable of producing polysaccharide to verify our results. Predictions of the glutamate source biofilm’s shape parameters agree with the experimental mutant colony better than that of glycerol source biofilm, suggesting that glutamate is rate limiting nutrient for Bacillus subtilis biofilm growth on agar plate, and the diffusion-limited is a better description to the experiment. In addition, we find that the diffusion time scale is of the same magnitude as growth process, and the common-employed quasi-steady approximation is not applicable here.

Simulation of Bacillus subtilis biofilm growth on agar plate by diffusion-reaction based continuum model.

PubMed

Zhang, Xianlong; Wang, Xiaoling; Nie, Kai; Li, Mingpeng; Sun, Qingping

2016-07-19

Various species of bacteria form highly organized spatially-structured aggregates known as biofilms. To understand how microenvironments impact biofilm growth dynamics, we propose a diffusion-reaction continuum model to simulate the formation of Bacillus subtilis biofilm on an agar plate. The extended finite element method combined with level set method are employed to perform the simulation, numerical results show the quantitative relationship between colony morphologies and nutrient depletion over time. Considering that the production of polysaccharide in wild-type cells may enhance biofilm spreading on the agar plate, we inoculate mutant colony incapable of producing polysaccharide to verify our results. Predictions of the glutamate source biofilm's shape parameters agree with the experimental mutant colony better than that of glycerol source biofilm, suggesting that glutamate is rate limiting nutrient for Bacillus subtilis biofilm growth on agar plate, and the diffusion-limited is a better description to the experiment. In addition, we find that the diffusion time scale is of the same magnitude as growth process, and the common-employed quasi-steady approximation is not applicable here.

Determination of antitrypsin activity on agar plates: relationship between antitrypsin and biological value of soybean for trout.

PubMed

Sandholm, M; Smith, R R; Shih, J C; Scott, M L

1976-06-01

A new method is described for determination of antitrypsin activity based on inhibition of trypsin solubilization of calcium caseinate in agar plates. The method was applied to analyze soybeans after graded heat treatments for their antitrypsin content. Biological determination of protein and energy values of the soybean samples showed direct correlation of these values with the destruction of antitrypsin as measured by the new method, using rainbow trout.

Enumeration of sublethally injured Escherichia coli O157:H7 ATCC 43895 and Escherichia coli strain B-41560 using selective agar overlays versus commercial methods.

PubMed

Smith, Amanda R; Ellison, Alysha L; Robinson, Amanda L; Drake, Maryanne; McDowell, Susan A; Mitchell, James K; Gerard, Patrick D; Heckler, Rachel A; McKillip, John L

2013-04-01

Quality control procedures during food processing may involve direct inoculation of food samples onto appropriate selective media for subsequent enumeration. However, sublethally injured bacteria often fail to grow, enabling them to evade detection and intervention measures and ultimately threaten the health of consumers. This study compares traditional selective and nonselective agar-based overlays versus two commercial systems (Petrifilm and Easygel) for recovery of injured E. coli B-41560 and O157:H7 strains. Bacteria were propagated in tryptic soy broth (TSB), ground beef slurry, and infant milk formula to a density of 10(6) to 10(8) CFU/ml and then were stressed for 6 min either in lactic acid (pH 4.5) or heat shocked for 3 min at 60°C. Samples were pour plated in basal layers of either tryptic soy agar (TSA), sorbitol MacConkey agar (SMAC), or violet red bile agar (VRB) and were resuscitated for 4 h prior to addition of agar overlays. Other stressed bacteria were plated directly onto Petrifilm and Easygel. Results indicate that selective and nonselective agar overlays recovered significantly higher numbers (greater than 1 log) of acid- and heat-injured E. coli O157:H7 from TSB, ground beef, and infant milk formula compared with direct plating onto selective media, Petrifilm, or Easygel, while no significant differences among these media combinations were observed for stressed E. coli B-41560. Nonstressed bacteria from TSB and ground beef were also recovered at densities significantly higher in nonselective TSA-TSA and in VRB-VRB and SMAC-SMAC compared with Petrifilm and Easygel. These data underscore the need to implement food safety measures that address sublethally injured pathogens such as E. coli O157:H7 in order to avoid underestimation of true densities for target pathogens.

Application of agar liquid-gel transition in cultivation and harvesting of microalgae for biodiesel production.

PubMed

Kumar, Vinod; Nanda, Manisha; Verma, Monu

2017-11-01

In order to increase microalgal biomass productivity efficient cultivation and harvesting methods are needed against the available traditional methods. The present study focuses on the same by harvesting microalgae using agar gel. Agar medium containing bold's basal medium (BBM) undergoes a thermoreversible gel transition. As compared to the traditional protocols, this gel is used to cultivate microalgae without even affecting the total productivity. To develop the gel for microalgae cultivation, agar was boiled in BBM. Then the agar was cooled to 35°C and microalgae culture was added to it. After seeding the microalgae the temperature of the agar was further decreased by 10°C to induce gelation. Instead of isolated cells microalgae were grown in clusters within the agar gel. Microalgal clusters gravimetrically settle at the bottom within 2h. In this method agar can be reused. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of a novel alkaline arylsulfatase from Marinomonas sp. FW-1 and its application in the desulfation of red seaweed agar.

PubMed

Wang, Xueyan; Duan, Delin; Xu, Jiachao; Gao, Xin; Fu, Xiaoting

2015-10-01

A bacterial strain capable of hydrolyzing sulfate ester bonds of p-nitrophenyl sulfate (pNPS) and agar was isolated from the coast area of Qingdao, China. It was identified as Marinomonas based on its 16S rRNA gene sequence and named as Marinomonas sp. FW-1. An arylsulfatase with a recovery of 13 % and a fold of 12 was purified to a homogeneity using ion exchange and gel filtration chromatographies. The enzyme was composed of a single polypeptide chain with the molecular mass of 33 kDa estimated using SDS-PAGE. The optimal pH and temperature of arylsulfatase were pH 9.0 and 45, respectively. Arylsulfatase was stable over pH 8-11 and at temperature below 55 °C. The K m and V max of this enzyme for the hydrolysis of pNPS were determined to be 13.73 and 270.27 μM/min, respectively. The desulfation ratio against agar from red seaweed Gelidium amansii and Gracilaria lemaneiformis were 86.11 and 89.61 %, respectively. There was no difference between the DNA electrophoresis spectrum on the gel of the arylsulfatase-treated G. amansii agar and that of the commercial agarose. Therefore, this novel alkaline arylsulfatase might have a great potential for application in enzymatic conversion of agar to agarose.

Comparison of 3 selective media for enumeration of Bacillus cereus in several food matrixes.

PubMed

Chon, Jung-Whan; Song, Kwang-Young; Kim, Hyunsook; Seo, Kun-Ho

2014-12-01

In this study, we compared the inclusivity, exclusivity, recoverability, and selectivity of the 3 selective agars (mannitol yolk polymyxin B agar [MYPA], polymyxin pyruvate egg yolk mannitol bromothymol blue agar [PEMBA], and Brillance Bacillus cereus agar [BBC agar]) for Bacillus cereus (B. cereus) from pure culture and several food samples. BBC agar showed greater exclusivity and selectivity in pure culture and in foods with high background flora, respectively; however, all the tested media showed similar recoverability (P > 0.05) of B. cereus in pure culture and in most foods. Our results suggest that BBC agar could be useful to enumerate B. cereus from, in particular, food matrixes with high background competing micro flora. © 2014 Institute of Food Technologists®

Comparison of Media for Detection of Fungi on Spacecraft

PubMed Central

Herring, C. M.; Brandsberg, J. W.; Oxborrow, G. S.; Puleo, J. R.

1974-01-01

Five media, including Trypticase soy agar (TSA; BBL) pour plates, spread plates of TSA, Mycophil agar with chloromycetin, Mycophil agar with chloromycetin and Actidione, and cornmeal agar with chloromycetin were quantitatively and qualitatively compared for the detection of fungi on spacecraft. Cornmeal agar with chloromycetin yielded the highest number of fungal colonies, although not always significantly higher than Mycophil agar with chloromycetin or TSA spread plates. Cornmeal agar with chloromycetin also gave the best qualitative representation of fungi on the spacecraft, recovering 68% of the genera found from all media. This medium yielded 10 times the number of fungal colonies and 3 times the number of genera found on TSA pour plates as currently used for spacecraft assay. PMID:4151044

Evaluation of Bacillus spp. as dough starters for Adhirasam - A traditional rice based fermented food of Southern India

PubMed Central

Anisha, Anvar Hussain Noorul; Anandham, Rangasamy; Kwon, Soon Woo; Gandhi, Pandiyan Indira; Gopal, Nellaiappan Olaganathan

2015-01-01

Abstract Adhirasam is a cereal based, doughnut shaped, deep fried dessert consumed in the southern regions of India. The dough used to prepare adhirasam is fermented and contains rice flour and jaggery. The aim of the present study was to characterize the cultivable bacteria associated with this fermented dough and to identify a suitable starter culture for the production of quality adhirasam. In total, one hundred and seventy bacterial isolates were recovered from de Man Rogosa Sharp (MRS) agar, nutrient agar, lysogeny agar and tryptic soy agar media. Out of the 170 bacterial isolates, sixteen isolates were selected based on their ability to tolerate glucose and sucrose. All the bacterial isolates tolerated 15% glucose and 30% sucrose. Analyses of 16S rDNA gene sequences of the bacterial isolates showed that the dominant cultivable bacteria were members of the genus Bacillus. These strains were further used as starters and tested for their ability to ferment rice flour with jaggery to produce adhirasam dough. Organoleptic evaluation was carried out to choose the best starter strain. Adhirasam prepared from Bacillus subtilis isolates S4-P11, S2-G2-A1 and S1-G15, Bacillus tequilensis isolates S2-H16, S3-P9, S3-G10 and Bacillus siamensis isolate S2-G13 were highly acceptable to consumers. Adhirasam prepared using these starter cultures had superior product characteristics such as softness in texture, flavor and enhanced aroma and sweet taste. PMID:26691480

Early responses of mature Arabidopsis thaliana plants to reduced water potential in the agar-based polyethylene glycol infusion drought model.

PubMed

Frolov, Andrej; Bilova, Tatiana; Paudel, Gagan; Berger, Robert; Balcke, Gerd U; Birkemeyer, Claudia; Wessjohann, Ludger A

2017-01-01

Drought is one of the most important environmental stressors resulting in increasing losses of crop plant productivity all over the world. Therefore, development of new approaches to increase the stress tolerance of crop plants is strongly desired. This requires precise and adequate modeling of drought stress. As this type of stress manifests itself as a steady decrease in the substrate water potential (ψ w ), agar plates infused with polyethylene glycol (PEG) are the perfect experimental tool: they are easy in preparation and provide a constantly reduced ψ w , which is not possible in soil models. However, currently, this model is applicable only to seedlings and cannot be used for evaluation of stress responses in mature plants, which are obviously the most appropriate objects for drought tolerance research. To overcome this limitation, here we introduce a PEG-based agar infusion model suitable for 6-8-week-old A. thaliana plants, and characterize, to the best of our knowledge for the first time, the early drought stress responses of adult plants grown on PEG-infused agar. We describe essential alterations in the primary metabolome (sugars and related compounds, amino acids and polyamines) accompanied by qualitative and quantitative changes in protein patterns: up to 87 unique stress-related proteins were annotated under drought stress conditions, whereas further 84 proteins showed a change in abundance. The obtained proteome patterns differed slightly from those reported for seedlings and soil-based models. Copyright © 2016 Elsevier GmbH. All rights reserved.

Investigation on the Formation of Needle Frost. II,

DTIC Science & Technology

For example, clay forms mutual layers with the clay which had not yet frozen with ice. In the case of agar-agar, we obtained the same phenomenon from gelidium jelly as we do when making agar-agar. (Author)

Discolored Red Seaweed Pyropia yezoensis with Low Commercial Value Is a Novel Resource for Production of Agar Polysaccharides.

PubMed

Sasuga, Keiji; Yamanashi, Tomoya; Nakayama, Shigeru; Ono, Syuetsu; Mikami, Koji

2018-04-26

The red seaweed Pyropia yezoensis has been demonstrated to be a novel resource for the production of high-quality agar. P. yezoensis is grown for the food industry in large-scale Japanese mariculture operations. However, discolored P. yezoensis is mostly discarded as an industrial waste, although it has some kind of utility values. Here, we evaluated the utility of discolored P. yezoensis as a resource for agar production. The quality of agar from the discolored seaweed was comparable to that from normal seaweed. In addition, as a distinguishing characteristic, agar yield was higher from discolored seaweeds than from normal types. Moreover, we successfully used agar from discolored P. yezoensis for bacterial plate media and DNA electrophoresis gels without agarose purification. Thus, our results demonstrate that discolored P. yezoensis is suitable for agar production and use in life science research. Diverting discolored P. yezoensis from disposal to agar production provides a solution to the current industrial waste problem in mariculture, as well as a secure source of agar for research purposes.

In Vitro Cultivation of 'Unculturable' Oral Bacteria, Facilitated by Community Culture and Media Supplementation with Siderophores.

PubMed

Vartoukian, Sonia R; Adamowska, Aleksandra; Lawlor, Megan; Moazzez, Rebecca; Dewhirst, Floyd E; Wade, William G

2016-01-01

Over a third of oral bacteria are as-yet-uncultivated in-vitro. Siderophores have been previously shown to enable in-vitro growth of previously uncultivated bacteria. The objective of this study was to cultivate novel oral bacteria in siderophore-supplemented culture media. Various compounds with siderophore activity, including pyoverdines-Fe-complex, desferricoprogen and salicylic acid, were found to stimulate the growth of difficult-to-culture strains Prevotella sp. HOT-376 and Fretibacterium fastidiosum. Furthermore, pyrosequencing analysis demonstrated increased proportions of the as-yet-uncultivated phylotypes Dialister sp. HOT-119 and Megasphaera sp. HOT-123 on mixed culture plates supplemented with siderophores. Therefore a culture model was developed, which incorporated 15 μg siderophore (pyoverdines-Fe-complex or desferricoprogen) or 150 μl neat subgingival-plaque suspension into a central well on agar plates that were inoculated with heavily-diluted subgingival-plaque samples from subjects with periodontitis. Colonies showing satellitism were passaged onto fresh plates in co-culture with selected helper strains. Five novel strains, representatives of three previously-uncultivated taxa (Anaerolineae bacterium HOT-439, the first oral taxon from the Chloroflexi phylum to have been cultivated; Bacteroidetes bacterium HOT-365; and Peptostreptococcaceae bacterium HOT-091) were successfully isolated. All novel isolates required helper strains for growth, implying dependence on a biofilm lifestyle. Their characterisation will further our understanding of the human oral microbiome.

Degradation of Coal by the Fungi Polyporus versicolor and Poria monticola

PubMed Central

Cohen, Martin S.; Gabriele, Peter D.

1982-01-01

We report that two species of basidiomycete fungi (Polyporus versicolor and Poria monticola) grow in minimal liquid or solid medium when supplemented with crushed lignite coal. The fungi also grow directly on crushed lignite coal. The growth of both fungi was observed qualitatively as the production and extension of hyphae. No fungal growth occurred in minimal agar medium without coal. The fungi degraded solid lignite coal to a black liquid product which never appeared in cultures unless fungi and coal were present together. Apparently, lignite coal can serve as the principal substrate for the growth of the fungi. Infrared analyses of the liquid products of lignite degradation showed both similarities to and differences from the original lignite. Images PMID:16346060

[THE NATIONAL NUTRIENT MEDIUM FOR DIAGNOSTIC OF PURULENT BACTERIAL MENINGITIS].

PubMed

Podkopaev, Ya V; Domotenko, L V; Morozova, T P; Khramov, M K; Shepelin, A P

2015-05-01

The national growth mediums were developed for isolating and cultivating of main agents of purulent bacterial meningitis--haemophilus agar, chocolate agar, PBM-agar. The growing and selective characteristics of developed growth mediums are examined. The haemophilus agar ensures growth of Haemophilus influenzae. The chocolate agar, PBM-agar ensure growth of Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae. By growing characteristics, the national growth mediums match foreign analogues. Under application of growth mediums with selective additions it is possible to achieve selective isolation of main agents of purulent bacterial meningitis with inhibition of growth of microbes-associates.

Comparison of m-Endo LES, MacConkey, and Teepol media for membrane filtration counting of total coliform bacteria in water.

PubMed Central

Grabow, W O; du Preez, M

1979-01-01

Total coliform counts obtained by means of standard membrane filtration techniques, using MacConkey agar, m-Endo LES agar, Teepol agar, and pads saturated with Teepol broth as growth media, were compared. Various combinations of these media were used in tests on 490 samples of river water and city wastewater after different stages of conventional purification and reclamation processes including lime treatment, and filtration, active carbon treatment, ozonation, and chlorination. Endo agar yielded the highest average counts for all these samples. Teepol agar generally had higher counts then Teepol broth, whereas MacConkey agar had the lowest average counts. Identification of 871 positive isolates showed that Aeromonas hydrophila was the species most commonly detected. Species of Escherichia, Citrobacter, Klebsiella, and Enterobacter represented 55% of isolates which conformed to the definition of total coliforms on Endo agar, 54% on Teepol agar, and 45% on MacConkey agar. Selection for species on the media differed considerably. Evaluation of these data and literature on alternative tests, including most probable number methods, indicated that the technique of choice for routine analysis of total coliform bacteria in drinking water is membrane filtration using m-Endo LES agar as growth medium without enrichment procedures or a cytochrome oxidase restriction. PMID:394678

Comparison of culture based methods for the isolation of Clostridium difficile from stool samples in a research setting.

PubMed

Lister, Michelle; Stevenson, Emma; Heeg, Daniela; Minton, Nigel P; Kuehne, Sarah A

2014-08-01

Effective isolation of Clostridium difficile from stool samples is important in the research setting, especially where low numbers of spores/vegetative cells may be present within a sample. In this study, three protocols for stool culture were investigated to find a sensitive, cost effective and timely method of C. difficile isolation. For the initial enrichment step, the effectiveness of two different rich media, cycloserine-cefoxitin fructose broth (CCFB) and cycloserine-cefoxitin mannitol broth with taurocholate and lysozyme (CCMB-TAL) were compared. For the comparison of four different, selective solid media; Cycloserine-cefoxitin fructose agar (CCFA), Cycloserine-cefoxitin egg yolk agar (CCEY), ChromID C. difficile and tryptone soy agar (TSA) with 5% sheep's blood with and without preceding broth enrichment were used. As a means to enable differentiation between C. difficile and other fecal flora, the effectiveness of the inclusion of a pH indictor (1% Neutral Red), was also evaluated. The data derived indicated that CCFB is more sensitive than CCMB-TAL, however, the latter had an improved recovery rate. A broth enrichment step had a reduced sensitivity over direct plating. ChromID C. difficile showed the best recovery rate whereas CCEY egg yolk agar was the most sensitive of the four. The addition of 1% Neutral Red did not show sufficient colour change when added to CCEY egg yolk agar to be used as a differential medium. For a low cost, timely and sensitive method of isolating C. difficile from stool samples we recommend direct plating onto CCEY egg yolk agar after heat shock. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

48 CFR 401.371 - AGAR Advisories.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false AGAR Advisories. 401.371 Section 401.371 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE GENERAL AGRICULTURE ACQUISITION REGULATION SYSTEM Agency Acquisition Regulations 401.371 AGAR Advisories. The SPE may issue AGAR...

Inference of Antibiotic Resistance and Virulence Among Diverse Group A Streptococcus Strains Using emm Sequencing and Multilocus Genotyping Methods

DTIC Science & Technology

2009-09-04

apparent GAS-associated conditions were sampled by oropharyn- geal swab. Swabs were streaked on blood agar plates using Table 3. Isolate properties by...testing, samples were re-streaked on blood agar plates (5% sheep blood in TSA base) (Hardy Diagnostics, Santa Maria, CA), and incubated at 35–37uC with 5–10...sensitivity (A-disk method, Hardy Diagnostics) and positive GAS latex agglutination reaction (Hardy Diagnostics). Confirmed GAS isolates were then

An (almost) solvable model for bacterial pattern formation

NASA Astrophysics Data System (ADS)

Grammaticos, B.; Badoual, M.; Aubert, M.

2007-10-01

We present a simple model for the description of ring-like concentric structures in bacterial colonies. We model the differences between Bacillus subtilis and Proteus mirabilis colonies by using a different dependence of the duration of the consolidation phase on the concentration of agar. We compare our results to experimental data from these two bacterial species colonies and obtain a good agreement. Based on this analysis, we formulate a hypothesis on the connection of the diffusion constant that appears in the model to the experimental agar concentration.

Radiation Resistance of Asporogenous Bacteria in Frozen Beef

DTIC Science & Technology

1976-03-01

Salmonella enteritidis , and Escherichia coli were used. Cultures were grown to the maximum stationary phase for use as an inoculum. Ground beef containing...eosin methylene blue agar, Shigella- Salmonella agar, and growth on plate count agar with 2.5% and 6.5% NaCl was observed. Penicillin susceptibility was...selective media as follows: Staphylococcus Medium No. 110 for S. aureus; Violet Red Bile Agar for E. coli; and Bismuth Sulfite Agar for S. enteritidis

Immobilization of pectin degrading enzyme from Bacillus licheniformis KIBGE IB-21 using agar-agar as a support.

PubMed

Rehman, Haneef Ur; Aman, Afsheen; Zohra, Raheela Rahmat; Qader, Shah Ali Ul

2014-02-15

Pectinase from Bacillus licheniformis KIBGE IB-21 was immobilized in agar-agar matrix using entrapment technique. Effect of different concentrations of agar-agar on pectinase immobilization was investigated and it was found that maximum immobilization was achieved at 3.0% agar-agar with 80% enzyme activity. After immobilization, the optimum temperature of enzyme increased from 45 to 50 °C and reaction time from 5 to 10 minutes as compared to free enzyme. Due to the limited diffusion of high molecular weight substrate, K(m) of immobilized enzyme slightly increased from 1.017 to 1.055 mg ml(-1), while Vmax decreased from 23,800 to 19,392 μM min(-1) as compared to free enzyme. After 120 h entrapped pectinase retained their activity up to 82% and 71% at 30 °C and 40 °C, respectively. The entrapped pectinase showed activity until 10th cycle and maintain 69.21% activity even after third cycle. Copyright © 2013 Elsevier Ltd. All rights reserved.

A novel agar formulation for isolation and direct enumeration of Vibrio vulnificus from oyster tissue.

PubMed

Griffitt, Kimberly J; Grimes, D Jay

2013-08-01

A new selective and differential medium, Vibrio vulnificus X-Gal (VVX), was developed for direct enumeration of V. vulnificus (Vv) from oyster samples. This agar utilizes cellobiose and lactose as carbon sources, and the antibiotics colistin and polymyxin B as selective agents. Hydrolysis of 5-bromo-4-chloro-3-indolyl- beta-d-galactopyranoside (x-gal), used in the agar as a lactose analog, produces an insoluble blue dye that makes lactose positive colonies easily distinguishable from any non-lactose fermenting bacteria. Various bacterial species were spot plated onto thiosulfate-citrate-bile salts-sucrose agar (TCBS), and CHROMagar Vibrio, two vibrio-specific selective agars, non-selective agar, and VVX to compare selectivity of VVX to other widely used media. A V. vulnificus pure culture was serially diluted on VVX and non-selective agar to determine the VVX percent recovery. Water and oyster samples were spread plated on VVX agar and allowed to incubate for 16-18 h at 33 °C. Blue and white colonies from VVX agar were picked and screened by end point PCR for the Vv hemolysin vvhA. VVX agar showed a significant improvement over TCBS and CHROMagar at preventing non-target growth. There was an 87.5% recovery compared to non-selective plating and a 98% positivity rate of blue colonies picked from oyster tissue plating. The findings suggest that this new agar is a fast, distinctive, and accurate method for enumeration of V. vulnificus from the environment. Copyright © 2013 Elsevier B.V. All rights reserved.

21 CFR 866.4600 - Ouchterlony agar plate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....4600 Ouchterlony agar plate. (a) Identification. An ouchterlony agar plate for clinical use is a device...

21 CFR 184.1115 - Agar-agar.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Agar-agar. 184.1115 Section 184.1115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific...

21 CFR 184.1115 - Agar-agar.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Agar-agar. 184.1115 Section 184.1115 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific...

21 CFR 866.4600 - Ouchterlony agar plate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ouchterlony agar plate. 866.4600 Section 866.4600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....4600 Ouchterlony agar plate. (a) Identification. An ouchterlony agar plate for clinical use is a device...

Control of in vitro rooting and plant development in Corymbia maculata by silver nitrate, silver thiosulfate and thiosulfate ion.

PubMed

Steinitz, Benjamin; Barr, Nurit; Tabib, Yona; Vaknin, Yiftach; Bernstein, Nirit

2010-11-01

Plant regeneration and transformation in vitro is often improved by adding silver ion (Ag(+)) to the culture media as AgNO(3) or silver thiosulfate (STS). Ag(+) reacts with substances to form insoluble precipitates, while thiosulfate (S(2)O(3) (2-)) interferes with these reactions. We studied the implications of silver precipitation and S(2)O(3) (2-) in the medium for culture development by (1) examining formation of Ag(+) precipitates from AgNO(3) versus STS in agar gels and their possible dependence on agar type; (2) comparing Corymbia maculata culture responses to AgNO(3) and STS and determining which better suits control of culture development; (3) clarifying whether STS-dependent alterations in culture development are due to Ag(+) alone or also to a separate influence of S(2)O(3) (2-). Silver precipitates appeared in aqueous gels of four agar brands supplemented with AgNO(3), but not in Phytagel(™), which remained transparent. No precipitation was observed in gels with STS. Indole-3-butyric acid (IBA)-mediated adventitious root induction and shoot growth were higher in C. maculata shoot tips cultured on gels with STS versus AgNO(3) (6-25 μM Ag(+)). IBA-treated shoot tips exhibited enhanced adventitious root regeneration, accelerated root elongation, increased frequency of lateral root formation, and stimulated shoot growth mediated by 100-250 μM sodium thiosulfate (Na(2)S(2)O(3)) in medium without Ag(+). The potency of S(2)O(3) (2-) in facilitating culture development has never been recognized. It is inferred that superiority of STS in stimulating multiple responses of C. maculata culture results from sustained biological activity of Ag(+) through prevention of its precipitation, and from impact of S(2)O(3) (2-) on cell differentiation and growth.

A new chromogenic medium for isolation of Bacteroides fragilis suitable for screening for strains with antimicrobial resistance.

PubMed

Tierney, Daniel; Copsey, Sarah D; Morris, Trefor; Perry, John D

2016-06-01

There have been an increasing number of reports describing the acquisition of antimicrobial resistance by Bacteroides fragilis including the occurrence of strains with resistance to multiple antimicrobials that are relied upon for treatment of infections. The aim of this study was to design a chromogenic selective medium for isolation of B. fragilis that could be adapted for specific isolation of antimicrobial-resistant strains. Bacteroides chromogenic agar (BCA) was the result of this endeavour and allowed growth of Bacteroides spp. as black colonies and the efficient inhibition of almost all other genera tested. The medium also allowed some differentiation of B. fragilis from other members of the B. fragilis group. When compared with an adaptation of Bacteroides bile-esculin agar (BBE) for the isolation of B. fragilis from 100 stool samples, 30 isolates of B. fragilis were recovered on BCA compared with 19 isolates recovered on BBE (P = 0.022). When supplemented with meropenem (4 μg/ml) or metronidazole (2 μg/ml), BCA could be used to select for the growth of B. fragilis isolates with resistance to these agents. We conclude that BCA is a useful research tool for surveillance studies to assess the prevalence of B. fragilis and, in particular, the occurrence of antimicrobial-resistant strains. Copyright © 2016 Elsevier Ltd. All rights reserved.

Diversity and dynamics of lactobacilli populations during ripening of RDO Camembert cheese.

PubMed

Henri-Dubernet, Ségolène; Desmasures, Nathalie; Guéguen, Micheline

2008-03-01

The diversity and dynamics of Lactobacillus populations in traditional raw milk Camembert cheese were monitored throughout the manufacturing process in 3 dairies. Culture-dependent analysis was carried out on isolates grown on acidified de Man - Rogosa - Sharpe agar and Lactobacillus anaerobic de Man Rogosa Sharpe agar supplemented with vancomycin and bromocresol green media. The isolates were identified by polymerase chain reaction - temperature gradient gel electrophoresis (PCR-TGGE) and (or) species-specific PCR and (or) sequencing, and Lactobacillus paracasei and Lactobacillus plantarum isolates were characterized by pulsed field gel electrophoresis (PFGE). Milk and cheese were subjected to culture-independent analysis by PCR-TGGE. Presumed lactobacilli were detected by plate counts throughout the ripening process. However, molecular analysis of total DNA and DNA of isolates failed to detect Lactobacillus spp. in certain cases. The dominant species in the 3 dairies was L. paracasei. PFGE analysis revealed 21 different profiles among 39 L. paracasei isolates. Lactobacillus plantarum was the second most isolated species, but it occurred nearly exclusively in one dairy. The other species isolated were Lactobacillus parabuchneri, Lactobacillus fermentum, Lactobacillus acidophilus, Lactobacillus helveticus, a Lactobacillus psittaci/delbrueckii subsp. bulgaricus/gallinarum/crispatus group, Lactobacillus rhamnosus, Lactobacillus delbrueckii subsp. bulgaricus, L. delbrueckii subsp. lactis, Lactobacillus brevis, Lactobacillus kefiri, and Lactobacillus perolens. Lactobacilli diversity at the strain level was high. Dynamics varied among dairies, and each cheese exhibited a specific picture of species and strains.

Radiolabeling of infective third-stage larvae of Strongyloides stercoralis by feeding ( sup 75 Se)selenomethionine-labeled Escherichia coli to first- and second-stage larvae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aikens, L.M.; Schad, G.A.

1989-10-01

A technique is described for radiolabeling Strongyloides stercoralis larvae with ({sup 75}Se)selenomethionine. Cultures of an auxotrophic methionine-dependent stain of Escherichia coli were grown in a medium containing Dulbecco's modified Eagle's medium supplemented with 5% nutrient broth, amino acids, and ({sup 75}Se)selenomethionine. When the {sup 75}Se-labeled bacterial populations were in the stationary phase of growth, cultures were harvested and the bacteria dispersed on agar plates to serve as food for S. stercoralis larvae. Use of nondividing bacteria is important for successful labeling because the isotope is not diluted by cell division and death of larvae attributable to overgrowth by bacteria ismore » prevented. First-stage S. stercoralis larvae were recovered from feces of infected dogs and reared in humid air at 30 C on agar plates seeded with bacteria. After 7 days, infective third-stage larvae were harvested. The mean specific activity of 6 different batches of larvae ranged from 75 to 330 counts per min/larva with 91.8 +/- 9.5% of the population labeled sufficiently to produce an autoradiographic focus during a practicable, 6-wk period of exposure. Labeled infective larvae penetrated the skin of 10-day-old puppies and migrated to the small intestine, where the developed to adulthood.« less

Performance of transport and selective media for swine Bordetella bronchiseptica recovery and it comparison to polymerase chain reaction detection

PubMed Central

Coutinho, Tania Alen; Bernardi, Mari Lourdes; de Itapema Cardoso, Marisa Ribeiro; Borowski, Sandra Maria; Moreno, Andrea Micke; de Barcellos, David Emilio Santos Neves

2009-01-01

Three comparative assays were performed seeking to improve the sensitivity of the diagnosis of Bordetella bronchiseptica infection analyzing swine nasal swabs. An initial assay compared the recovery of B. bronchiseptica from swabs simultaneously inoculated with B. bronchiseptica and some interfering bacteria, immersed into three transport formulations (Amies with charcoal, trypticase soy broth and phosphate buffer according to Soerensen supplemented with 5% of bovine fetal serum) and submitted to different temperatures (10°C and 27°C) and periods of incubation (24, 72 and 120 hours). A subsequent assay compared three selective media (MacConkey agar, modified selective medium G20G and a ceftiofur medium) for their recovery capabilities from clinical specimens. One last assay compared the polymerase chain reaction to the three selective media. In the first assay, the recovery of B. bronchiseptica from transport systems was better at 27°C and the three formulations had good performances at this temperature, but the collection of qualitative and quantitative analysis indicated the advantage of Amies medium for nasal swabs transportation. The second assay indicated that MacConkey agar and modified G20G had similar results and were superior to the ceftiofur medium. In the final assay, polymerase chain reaction presented superior capability of B. bronchiseptica detection to culture procedures. PMID:24031390

Biofilm formation, cellulose production, and curli biosynthesis by Salmonella originating from produce, animal, and clinical sources.

PubMed

Solomon, Ethan B; Niemira, Brendan A; Sapers, Gerald M; Annous, Bassam A

2005-05-01

The ability of 71 strains of Salmonella enterica originating from produce, meat, or clinical sources to form biofilms was investigated. A crystal violet binding assay demonstrated no significant differences in biofilm formation by isolates from any source when tested in any of the following three media: Luria-Bertani broth supplemented with 2% glucose, tryptic soy broth (TSB), or 1/20th-strength TSB. Incubation was overnight at 30 degrees C under static conditions. Curli production and cellulose production were monitored by assessing morphotypes on Luria-Bertani agar without salt containing Congo red and by assessing fluorescence on Luria-Bertani agar containing calcofluor, respectively. One hundred percent of the clinical isolates exhibited curli biosynthesis, and 73% demonstrated cellulose production. All meat-related isolates formed curli, and 84% produced cellulose. A total of 80% of produce-related isolates produced curli, but only 52% produced cellulose. Crystal violet binding was not statistically different between isolates representing the three morphotypes when grown in TSB; however, significant differences were observed when strains were cultured in the two other media tested. These data demonstrate that the ability to form biofilms is not dependent on the source of the test isolate and suggest a relationship between crystal violet binding and morphotype, with curli- and cellulose-deficient isolates being least effective in biofilm formation.

Comparison of four β-glucuronidase and β-galactosidase-based commercial culture methods used to detect Escherichia coli and total coliforms in water.

PubMed

Maheux, Andrée F; Dion-Dupont, Vanessa; Bouchard, Sébastien; Bisson, Marc-Antoine; Bergeron, Michel G; Rodriguez, Manuel J

2015-06-01

The MI agar, Colilert(®), Chromocult coliform(®) agar, and DC with BCIG agar chromogenic culture-based methods used to assess microbiological quality of drinking water were compared in terms of their ubiquity, sensitivity, ease of use, growth of atypical colonies and affordability. For ubiquity, 129 total coliform (representing 76 species) and 19 Escherichia coli strains were tested. Then, 635 1-L well water samples were divided into 100 mL subsamples for testing by all four methods. Test results showed that 70.5, 52.7, 36.4, and 23.3% of the non-E. coli total coliform strains and 94.7, 94.7, 89.5, and 89.5% of the 19 E. coli strains yielded a positive signal with the four methods, respectively. They also yielded a total coliform positive signal for 66.5, 51.7, 64.9, and 55.0% and an E. coli positive signal for 16.1, 14.8, 17.3, and 13.4% of the 635 well water samples tested, respectively. Results showed that Colilert(®) is the most expensive method tested in terms of reactants, yet it is the easiest to use. Large numbers of atypical colonies were also often observed on Chromocult coliform(®) and DC with BCIG, thereby challenging the target microorganism count. Thus, the MI agar method seems to be the best option for the assessment of drinking water quality.

Modification of kanamycin-esculin-azide agar to improve selectivity in the enumeration of fecal streptococci from water samples.

PubMed

Audicana, A; Perales, I; Borrego, J J

1995-12-01

Kanamycin-esculin-azide agar was modified by increasing the concentration of sodium azide to 0.4 g liter-1 and replacing kanamycin sulfate with 5 mg of oxolinic acid liter-1. The modification, named oxolinic acid-esculin-azide (OAA) agar, was compared with Slanetz-Bartley and KF agars by using drinking water and seawater samples. The OAA agar showed higher specificity, selectivity, and recovery efficiencies than those obtained by using the other media. In addition, no confirmation of typical colonies was needed when OAA agar was used, which significantly shortens the time of sample processing and increases the accuracy of the method.

Modification of kanamycin-esculin-azide agar to improve selectivity in the enumeration of fecal streptococci from water samples.

PubMed Central

Audicana, A; Perales, I; Borrego, J J

1995-01-01

Kanamycin-esculin-azide agar was modified by increasing the concentration of sodium azide to 0.4 g liter-1 and replacing kanamycin sulfate with 5 mg of oxolinic acid liter-1. The modification, named oxolinic acid-esculin-azide (OAA) agar, was compared with Slanetz-Bartley and KF agars by using drinking water and seawater samples. The OAA agar showed higher specificity, selectivity, and recovery efficiencies than those obtained by using the other media. In addition, no confirmation of typical colonies was needed when OAA agar was used, which significantly shortens the time of sample processing and increases the accuracy of the method. PMID:8534085

Evaluation of nutrient agar for the culture of Mycobacterium tuberculosis using the microcolony detection method.

PubMed

Satti, L; Abbasi, S; Faiz, U

2012-07-01

We evaluated nutrient agar using the microcolony detection method for the recovery of Mycobacterium tuberculosis on 37 acid-fast bacilli (AFB) positive sputum specimens, and compared it with conventional Löwenstein-Jensen (LJ) medium. Nutrient agar detected 35 isolates compared to 34 on LJ medium. The mean time to detection of mycobacteria on nutrient agar and LJ medium was respectively 9.6 and 21.4 days. The contamination rate on nutrient agar and LJ medium was respectively 5.4% and 2.7%. Nutrient agar detects M. tuberculosis more rapidly than LJ medium, and could be an economical, rapid culture method in resource-poor settings, provided our findings are confirmed by further studies.

Combination of nutrients in a mammalian cell culture medium kills cryptococci.

PubMed

Granger, Donald L; Call, Donna M

2018-06-06

We found that a large inoculum of Cryptococcus gattii cells, when plated on Dulbecco's modified eagle's medium (DMEM) incorporated into agar, died within a few hours provided that DMEM agar plates had been stored in darkness for approximately 3 days after preparation. Standard conditions were developed for quantification of killing. The medium lost its fungicidal activity when exposed to visible light of wave length ∼400 nm. The amount of energy required was estimated at 5.8 × 104 joules @ 550 nm. Liquid DMEM conditioned by incubation over DMEM agar plates stored in darkness was fungicidal. We found that fungicidal activity was heat-stable (100°C). Dialysis tubing with MWC0 < 100 Daltons retained fungicidal activity. Neutral pH was required. Strains of Cryptococcus were uniformly sensitive, but some Candida species were resistant. Components of DMEM required for killing were pyridoxal and cystine. Micromolar amounts of iron shortened the time required for DMEM agar plates to become fungicidal when stored in the dark. Organic and inorganic compounds bearing reduced sulfur atoms at millimolar concentrations inhibited fungicidal activity. Our results point to a light-sensitive antifungal compound formed by reaction of pyridoxal with cystine possibly by Schiff base formation.

Color features as an approach for the automated screening of Salmonella strain

NASA Astrophysics Data System (ADS)

Trujillo, Alejandra Serrano; González, Viridiana Contreras; Andrade Rincón, Saulo E.; Palafox, Luis E.

2016-11-01

We present the implementation of a feature extraction approach for the automated screening of Salmonella sp., a task visually carried out by a microbiologist, where the resulting color characteristics of the culture media plate indicate the presence of this strain. The screening of Salmonella sp. is based on the inoculation and incubation of a sample on an agar plate, allowing the isolation of this strain, if present. This process uses three media: Xylose lysine deoxycholate, Salmonella Shigella, and Brilliant Green agar plates, which exhibit specific color characteristics over the colonies and over the surrounding medium for a presumed positive interpretation. Under a controlled illumination environment, images of plates are captured and the characteristics found over each agar are processed separately. Each agar is analyzed using statistical descriptors for texture, to determine the presence of colonies, followed by the extraction of color features. A comparison among the color features seen over the three media, according to the FDA Bacteriological Analytical Manual, determines the presence of Salmonella sp. on a given sample. The implemented process proves that the task addressed can be accomplished under an image processing approach, leading to the future validation and automation of additional screening processes.

Multi-chamber electroosmosis using textile reinforced agar membranes--A promising concept for the future of hemodialysis.

PubMed

Kofler, Markus; Lenninger, Margit; Mayer, Gert; Neuwirt, Hannes; Grimm, Michael; Bechtold, Thomas

2016-01-20

Renal replacement therapy options are limited to hemodialysis and peritoneal dialysis (70% of US patients) or renal transplantation. Diffusion processes are the main physico-chemical principle behind hemodialysis. An alternative way to achieve liquid flow through membranes bases on the electroosmotic flow which is observed as electrokinetic phenomenon in porous membranes which bear surface charges. Agar consists of the non-ionic agarose and the negatively charged agaropectine thus an electroosmotic flux is observed in analytical electrophoresis. In this study the potential electroosmosis on textile reinforced agar membranes as separation method was investigated. Using a five-chamber electrolysis cell and an agar membrane/cellulose fabric composite an intensive electroosmotic flow of 1-2 ml cm(2) h(-1) at 100 mA cell current could be observed. The movement of cations in the negatively charged agar structure led to an intensive electroosmotic flux, which also transported uncharged molecules such as urea, glucose through the membrane. Separation of uncharged low molecular weight molecules is determined by the membrane characteristic. The transport of ions (K(+), PO4(3-), creatinine) and uncharged molecules (urea, glucose) in electroosmotic separation experiments was monitored using a pH 5.5 phosphate electrolyte with the aim to assess the overall transport processes in the electrochemical cell. The results demonstrate the potential of the method for filtration of biological fluids in the absence of external pressure or high shear rates. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hyperspectral image reconstruction using RGB color for foodborne pathogen detection on agar plates

NASA Astrophysics Data System (ADS)

Yoon, Seung-Chul; Shin, Tae-Sung; Park, Bosoon; Lawrence, Kurt C.; Heitschmidt, Gerald W.

2014-03-01

This paper reports the latest development of a color vision technique for detecting colonies of foodborne pathogens grown on agar plates with a hyperspectral image classification model that was developed using full hyperspectral data. The hyperspectral classification model depended on reflectance spectra measured in the visible and near-infrared spectral range from 400 and 1,000 nm (473 narrow spectral bands). Multivariate regression methods were used to estimate and predict hyperspectral data from RGB color values. The six representative non-O157 Shiga-toxin producing Eschetichia coli (STEC) serogroups (O26, O45, O103, O111, O121, and O145) were grown on Rainbow agar plates. A line-scan pushbroom hyperspectral image sensor was used to scan 36 agar plates grown with pure STEC colonies at each plate. The 36 hyperspectral images of the agar plates were divided in half to create training and test sets. The mean Rsquared value for hyperspectral image estimation was about 0.98 in the spectral range between 400 and 700 nm for linear, quadratic and cubic polynomial regression models and the detection accuracy of the hyperspectral image classification model with the principal component analysis and k-nearest neighbors for the test set was up to 92% (99% with the original hyperspectral images). Thus, the results of the study suggested that color-based detection may be viable as a multispectral imaging solution without much loss of prediction accuracy compared to hyperspectral imaging.

Dehumidifier assisted drying of a model fruit pulp-based gel and sensory attributes.

PubMed

Tiwari, Shipra; Ravi, Ramasamy; Bhattacharya, Suvendu

2012-07-01

Model fruit pulp-based gels were prepared by varying mango pulp (0% to 50%), sucrose (0% to 20%), and agar (1% to 3%) and according to a response surface experimental design followed by drying at a low temperature of 40 °C upto 15 h in a tray dryer assisted by a dehumidifier. The moisture content, shrinkage (SHR), and rheological parameters (failure strain, failure stress (FS), firmness, and energy for compression) were determined as a function of drying time. The composition of gel, particularly the agar content had a prominent effect on the characteristics of the dried gel. Detailed descriptive sensory analysis employing principle component analysis (PCA) biplot indicated two distinct groups of attributes; the first group comprised initial and final moisture contents, extent of moisture removal (EMR), and shrinkage. The fracture stress and energy formed the second group. The analysis of variance for failure stress showed that it depended only on the positive linear and quadratic effects of agar (significant at P ≤ 0.01 and 0.05, respectively). The theoretically predicted extent of moisture removal at 95.6% could be achieved when the level of agar was 1.2%; pulp and sucrose levels were also close to their lowest levels of 3.6% and 0.04%, respectively. Scope exists to develop gel-based fruit analogues wherein an appropriate hydrocolloid can be employed along with fruit juice/pulp. To provide a reasonable shelf-life of the developed intermediate moisture containing product, dehumidifier assisted drying is a pragmatic approach that affects sensory and rheological attributes of the dried fruit analogue. © 2012 Institute of Food Technologists®

Development of novel Alicyclobacillus spp. isolation medium.

PubMed

Chang, S; Kang, D-H

2005-01-01

To develop a new isolation medium with higher recovery rates of Alicyclobacillus spp. SK agar was developed with optimized incubation temperature, pH, acidulant, Tween 80 concentration and divalent cation addition. Results indicate that detection of Alicyclobacillus spp. by SK agar was significantly higher (P > 0.05) than those obtained by K agar, orange serum agar, and potato dextrose agar. Current media used for Alicyclobacillus spp. isolation still resulted in high numbers of false negative products. The sensitivity of SK agar to Alicyclobacillus spp. allows detection of low numbers of Alicyclobacillus spp. and also provides a more higher isolation results compared with currently used media. SK agar will be useful to the fruit juice industry to obtain more accurate numbers of contaminant Alicyclobacillus spp. With this media, false negative samples can be reduced, and the likelihood of exported products being rejected can be greatly reduced.

Comparison of Guizotia abyssinica seed extract (birdseed) agar with conventional media for selective identification of Cryptococcus neoformans in patients with acquired immunodeficiency syndrome.

PubMed Central

Denning, D W; Stevens, D A; Hamilton, J R

1990-01-01

Growth of Cryptococcus neoformans from the sputum of patients with acquired immunodeficiency syndrome may be obscured by oral contamination with Candida albicans on conventional media. We prospectively compared direct plating of sputum and urine onto birdseed agar and compared birdseed agar plating with plating onto Mycosel and Sabouraud dextrose agar cultures. Thirty-two sputum and three urine specimens were compared. C. neoformans was isolated from five specimens. In two specimens, one of sputum and one of urine, C. neoformans was detected only on the birdseed agar plate because of overgrowth on the conventional media by C. albicans. C. neoformans produced dark colonies on birdseed agar, unlike C. albicans, which produces white colonies. The use of birdseed agar as the primary culture medium for sputum and urine specimens from patients with acquired immunodeficiency syndrome increases sensitivity for C. neoformans. Images PMID:2254431

Influence of Structural Properties and Kinetic Constraints on Bacillus cereus Growth

PubMed Central

Stecchini, Mara Lucia; Del Torre, Manuela; Sarais, Ileana; Saro, Onorio; Messina, Mariella; Maltini, Enrico

1998-01-01

The influence of structural properties and kinetic constraints on the behavior of Bacillus cereus was investigated on agar media. Dimensional criteria were used to study the growth in bacterial colonies. The architecture of the agar gel as modified by the agar content was found to influence the colony size, and smaller colonies were observed on media containing 50 to 70 g of agar liter−1. Except at low nutrient levels, colonies responded to nutrient gradients by decreasing in size the farther away they were from the nutrient source, and the decrease in colony size was influenced by the agar content. The diffusivities of glucose and a protein (insulin-like growth factor) were not affected by the gel architecture, suggesting that other factors, such as mechanical factors, could influence microbial growth in the agar systems used. Increasing the viscosity of the liquid phase of the agar media by adding polyvinylpyrrolidone resulted in a reduction in colony size. When the agar concentration was increased, the colony areas were not influenced by the viscosity of the system. PMID:9501447

Physicochemical and morphological properties of plasticized poly(vinyl alcohol)-agar biodegradable films.

PubMed

Madera-Santana, T J; Freile-Pelegrín, Y; Azamar-Barrios, J A

2014-08-01

The effects of the addition of glycerol (GLY) on the physicochemical and morphological properties of poly(vinyl alcohol) (PVA)-agar films were reported. PVA-agar films were prepared by solution cast method, and the addition of GLY in PVA-agar films altered the optical properties, resulting in a decrease in opacity values and in the color difference (ΔE) of the films. Structural characterization using Fourier transformation infrared (FTIR) spectroscopy and X-ray diffraction (XRD) indicated that the presence of GLY altered the intensity of the bands (from 1200 to 800cm(-1)) and crystallinity. The characterization of the thermal properties indicated that an increase in the agar content produces a decrease in the melting temperature and augments the heat of fusion. Similar tendencies were observed in plasticized films, but at different magnification. The formulation that demonstrated the lowest mechanical properties contained 25wt.% agar, whereas the formulation that contained 75wt.% agar demonstrated a significant improvement. The water vapor transmission rate (WVTR) and surface morphology analysis demonstrated that the structure of PVA-agar films is reorganized upon GLY addition. The physicochemical properties of PVA-agar films using GLY as a plasticizer provide information for the application of this formulation as packaging material for specific food applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Study of the lactic acid bacteria throughout the manufacture of dry-cured lacón (a Spanish traditional meat product). Effect of some additives.

PubMed

Lorenzo, José M; García Fontán, María C; Cachaldora, Aida; Franco, Inmaculada; Carballo, Javier

2010-04-01

Total aerobic mesophilic microflora (on SPC agar), lactic acid bacteria (on MRS agar) and lactobacilli (on Rogosa agar) were enumerated in samples from the surface and the interior of the pieces throughout the manufacture of six batches of lacón. Three of the batches were made without additives and three with additives (glucose (2 g/kg), sodium nitrite (E(250)) (125 mg/kg), sodium nitrate (E(251)) (175 mg/kg), sodium ascorbate (E(301)) (500 mg/kg), and sodium citrate (E(331)) (100 mg/kg)). The counts decreased throughout the manufacturing process, particularly after the salting stage. The use of additives did not affect the counts or the evolution of the microbial groups, except for the lactobacilli, which were present in higher numbers in the batches with additives. In four batches (two without and two with additives), from MRS agar and from Rogosa agar plates, 10 colonies were randomly taken from each sampling point of each batch (five from the surface sample and five from the interior sample) and from each culture medium; a total of 224 strains from MRS agar, and 176 strains from Rogosa agar that were identified by classical methods. The MRS agar displayed moderate selectivity for the isolation of lactic acid bacteria, and only 59% of the isolated strains belonged to this microbial group. Homofermentative and facultative heterofermentative lactobacilli (particularly Lactobacillus curvatus and Lactobacillus sakei) were the most abundant species isolated on this medium. The selectivity of the Rogosa agar for lactobacilli was extremely high. The species of lactobacilli isolated on this medium at different stages of manufacture of the four batches of lacón were consistent with those isolated from MRS agar. The use of additives in the lacón did not appreciably affect the kinds and proportions of species isolated on either MRS agar or Rogosa agar.

A modified culture-based study of bacterial community composition in a tannery wastewater treatment plant.

PubMed

Desta, Adey F; Dalhammer, Gunnel; Kittuva, Gunatrana R

2010-01-01

Though culture-independent methods have been used in preference to traditional isolation techniques for characterization of microbial community of wastewater treatment plants, it is difficult to widely apply this approach in resource-poor countries. The present study aimed to develop a test to identify the culturable portion of bacterial community in a high-strength wastewater. Wastewater samples were collected from nitrification-denitrification and settling tanks of the treatment plant of Elmo Leather AB tannery located in Borås, Sweden. After cultivating on nutrient agar with the optimal dilution (10⁻²), phenotypic and biochemical identification of the bacteria were done with colony morphology, Gram reaction, growth on MacConkey, phenylethanol media, triple sugar Iron agar slants, catalase and oxidase tests. Biochemical grouping of the isolates was done based on their test results for MacConkey, phenylethanol media, triple sugar Iron agar and oxidase test reaction. From the biochemical groups, isolates were randomly selected for API test and 16SrRNA gene sequencing. The isolates from the denitrification, nitrification tank were identified to be Paracoccus denitrificans (67%), Azoarcus spp (3%) and Spingomonas wittichii (1%). From the settling tank, Paracoccus denitrificans (22%), Corynebacterium freneyi (20%) and Bacillus cereus (1%) were identified. The grouping based on biochemical test results as well as the identification based on sequencing has shown coherence except for discrepancies with the API test. The preliminary implications of the grouping based on culture-based characteristics and its potential application for resource-limited environmental microbial studies is discussed.

Three-dimensional characterization of bacterial microcolonies on solid agar-based culture media.

PubMed

Drazek, Laurent; Tournoud, Maud; Derepas, Frédéric; Guicherd, Maryse; Mahé, Pierre; Pinston, Frédéric; Veyrieras, Jean-Baptiste; Chatellier, Sonia

2015-02-01

For the last century, in vitro diagnostic process in microbiology has mainly relied on the growth of bacteria on the surface of a solid agar medium. Nevertheless, few studies focused in the past on the dynamics of microcolonies growth on agar surface before 8 to 10h of incubation. In this article, chromatic confocal microscopy has been applied to characterize the early development of a bacterial colony. This technology relies on a differential focusing depth of the white light. It allows one to fully measure the tridimensional shape of microcolonies more quickly than classical confocal microscopy but with the same spatial resolution. Placing the device in an incubator, the method was able to individually track colonies growing on an agar plate, and to follow the evolution of their surface or volume. Using an appropriate statistical modeling framework, for a given microorganism, the doubling time has been estimated for each individual colony, as well as its variability between colonies, both within and between agar plates. A proof of concept led on four bacterial strains of four distinct species demonstrated the feasibility and the interest of the approach. It showed in particular that doubling times derived from early tri-dimensional measurements on microcolonies differed from classical measurements in micro-dilutions based on optical diffusion. Such a precise characterization of the tri-dimensional shape of microcolonies in their late-lag to early-exponential phase could be beneficial in terms of in vitro diagnostics. Indeed, real-time monitoring of the biomass available in a colony could allow to run well established microbial identification workflows like, for instance, MALDI-TOF mass-spectrometry, as soon as a sufficient quantity of material is available, thereby reducing the time needed to provide a diagnostic. Moreover, as done for pre-identification of macro-colonies, morphological indicators such as three-dimensional growth profiles derived from microcolonies could be used to perform a first pre-identification step, but in a shorten time. Copyright © 2014 Elsevier B.V. All rights reserved.

[FEATURES OF MASS-SPECTROMETRIC PROTEIN PROFILES OF STRAINS OF BRUCELLOSIS CAUSATIVE AGENT DURING PREPARATION OF CULTURE ON VARIOUS NUTRIENT MEDIA].

PubMed

Ulshina, D V; Kovalev, D A; Zhirov, A M; Zharinova, N V; Khudoleev, A A; Kogotkova, O I; Efremenko, V I; Evchenko, N I; Kulichenko, A N

2016-01-01

Carry out comparative analysis using time-of-flight mass-spectrometry with matrix laser desorption/ionization (MALDI-TOF MS) of protein profiles of brucellosis causative agents (Brucella melitensis Rev-1 and Brucella abortus 19BA), cultivated in various nutrient media: Albimi agar, brucellagar and erythrit-agar. Vaccine,strains: Brucella melitensis Rev-1 and Brucella abortus 19BA. Protein profiling in linear mode on Microflex "Bruker Daltonics" MALDI-TOF mass-spectrometer. A number of characteristic features of brucella mass-spectra was detected: in particular, preservation of the total qualitative composition of protein profiles of cultures and significant differences in the intensity of separate peaks depending on the nutrient medium used. Based on the analysis of the data obtained, use of Albimi agar as the nutrient medium for preparation of brucella culture samples for mass-spectrometric analysis was shown to be optimal.

Improved Medium for Selecting Nitrate-Nonutilizing (nit) Mutants of Verticillium dahliae.

PubMed

Korolev, N; Katan, T

1997-10-01

ABSTRACT Nitrate-nonutilizing (nit) mutants are commonly used to determine vegetative compatibility between isolates of Verticillium dahliae by complementation (heterokaryon) testing. These mutants emerge spontaneously as chlorate-resistant sectors growing out of partially restricted, wild-type colonies on chlorate-amended media. The commonly used chlorate media are based on minimal medium (MMC) or cornmeal agar (CMC), amended with potassium chlorate. nit mutants recovered on these media constituted 10 to 36%(on MMC) and 25 to 45%(on CMC) of the apparently resistant sectors. An improved water agar chlorate medium (WAC) is described that is more effective for selecting chlorate-resistant nit mutants. WAC medium consists of agar (2%), glucose (0.02%), and potassium chlorate (2 to 5%). On WAC, growth of most V. dahliae isolates was strongly inhibited, and 66 to 100%(average >80%) of the chlorate-resistant sectors formed were nit mutants. Most mutants were characterized as nit1, and about 6% as NitM.

Hollow-Fiber Membrane Chamber as a Device for In Situ Environmental Cultivation▿

PubMed Central

Aoi, Yoshiteru; Kinoshita, Tomoyuki; Hata, Toru; Ohta, Hiroaki; Obokata, Haruko; Tsuneda, Satoshi

2009-01-01

A hollow-fiber membrane chamber (HFMC) was developed as an in situ cultivation device for environmental microorganisms. The HFMC system consists of 48 to 96 pieces of porous hollow-fiber membrane connected with injectors. The system allows rapid exchange of chemical compounds, thereby simulating a natural environment. Comparative analysis through the cultivation of three types of environmental samples was performed using this newly designed device and a conventional agar-based petri dish. The results show that the ratios of novel phylotypes in isolates, species-level diversities, and cultivabilities in HFMC-based cultivation are higher than those in an agar-based petri dish for all three samples, suggesting that the new in situ cultivation device is effective for cultivation of various environmental microorganisms. PMID:19329655

Selection of Fecal Enterococci Exhibiting tcrB-Mediated Copper Resistance in Pigs Fed Diets Supplemented with Copper † ▿

PubMed Central

Amachawadi, R. G.; Shelton, N. W.; Shi, X.; Vinasco, J.; Dritz, S. S.; Tokach, M. D.; Nelssen, J. L.; Scott, H. M.; Nagaraja, T. G.

2011-01-01

Copper, as copper sulfate, is increasingly used as an alternative to in-feed antibiotics for growth promotion in weaned piglets. Acquired copper resistance, conferred by a plasmid-borne, transferable copper resistance (tcrB) gene, has been reported in Enterococcus faecium and E. faecalis. A longitudinal field study was undertaken to determine the relationship between copper supplementation and the prevalence of tcrB-positive enterococci in piglets. The study was done with weaned piglets, housed in 10 pens with 6 piglets per pen, fed diets supplemented with a normal (16.5 ppm; control) or an elevated (125 ppm) level of copper. Fecal samples were randomly collected from three piglets per pen on days 0, 14, 28, and 42 and plated on M-Enterococcus agar, and three enterococcal isolates were obtained from each sample. The overall prevalence of tcrB-positive enterococci was 21.1% (38/180) in piglets fed elevated copper and 2.8% (5/180) in the control. Among the 43 tcrB-positive isolates, 35 were E. faecium and 8 were E. faecalis. The mean MICs of copper for tcrB-negative and tcrB-positive enterococci were 6.2 and 22.2 mM, respectively. The restriction digestion of the genomic DNA of E. faecium or E. faecalis with S1 nuclease yielded a band of ∼194-kbp size to which both tcrB and the erm(B) gene probes hybridized. A conjugation assay demonstrated cotransfer of tcrB and erm(B) genes between E. faecium and E. faecalis strains. The higher prevalence of tcrB-positive enterococci in piglets fed elevated copper compared to that in piglets fed normal copper suggests that supplementation of copper in swine diets selected for resistance. PMID:21705534

Organic amendments enhance Pb tolerance and accumulation during micropropagation of Daphne jasminea.

PubMed

Wiszniewska, Alina; Muszyńska, Ewa; Hanus-Fajerska, Ewa; Smoleń, Sylwester; Dziurka, Michał; Dziurka, Kinga

2017-01-01

The study investigated the effects of organic amendments: pineapple pulp (PP) and agar hydrolyzate (AH), on micropropagation and Pb bioaccumulation and tolerance in a woody shrub Daphne jasminea cultured in vitro. The amendments were analyzed for their content of carbohydrates, phenolic acids, and phytohormones and added at a dose of 10 mL L -1 to the medium containing 1.0 mM lead nitrate. Micropropagation coefficient increased by 10.2-16.6 % in PP and AH variants, respectively. Growth tolerance index increased by 22.9-31.8 % for the shoots and by 60.1-82.4 % for the roots. In the absence of Pb, the additives inhibited multiplication and growth of microplantlets. PP and AH facilitated Pb accumulation in plant organs, especially in the roots. PP enhanced bioconcentration factor and AH improved Pb translocation to the shoots. Adaptation to Pb was associated with increased accumulation of phenolics and higher radical scavenging activity. Medium supplementation, particularly with AH, enhanced antiradical activity of Pb-adapted lines but reduced the content of phenolic compounds. The study results indicated that supplementation with organic amendments may be beneficial in in vitro selection against lead toxicity.

Macroconidial development and germination in Trichophyton mentagrophytes.

PubMed

Niimi, K; Niimi, M; Harada, K; Tokunaga, M; Tokunaga, J

1988-02-01

Trichophyton Mentagrophytes was investigated for macroconidial development with particular emphasis on the conidial ageing by light and scanning electron microscopy. Macroconidial germination was also studied under various conditions. Sabouraud glucose agar supplemented with 3% NaCl was used to enhance production of macroconidia. After a long-term cultivation macroconidial compartments changed to spherical thick-walled structure. Some 12-month-old macroconidia were still capable of germination. A wide range of temperature (15-37 degrees C), and inoculum of less than 1 X 10(5) conidia per ml of rich media were appropriate for macroconidial germination. The germination process of macroconidia was highly tolerant to NaCl. A small fraction of the conidia were able to germinate even in distilled water without activation. Effect of freeze-thaw or ultraviolet irradiation on macroconidial germination was determined.

Agar Block Smear Preparation: a Novel Method of Slide Preparation for Preservation of Native Fungal Structures for Microscopic Examination and Long-Term Storage▿

PubMed Central

Woo, Patrick C. Y.; Ngan, Antonio H. Y.; Chui, Hon-Kit; Lau, Susanna K. P.; Yuen, Kwok-Yung

2010-01-01

We describe a novel method of fungal slide preparation named “agar block smear preparation.” A total of 510 agar block smears of 25 fungal strains obtained from culture collections, 90 QC fungal strains, and 82 clinical fungal strains from our clinical microbiology laboratory, which included a total of 137 species of yeasts, molds, and thermal dimorphic fungi, were prepared and examined. In contrast to adhesive tape preparation, agar block smears preserved the native fungal structures, such as intact conidiophores of Aspergillus species and arrangements of conidia in Scopulariopsis brevicaulis. Furthermore, agar block smears allowed examination of fungal structures embedded in the agar, such as the ascomata with ascomal hairs in Chaetomium funicola; pycnidium of Phoma glomerata; the intercalary ovoidal chlamydospores arranged in chains of Fusarium dimerum; and the lateral, spherical chlamydospores arranged in pairs of Fusarium solani. After 1 year of storage, morphological integrity was found to have been maintained in 459 (90%) of the 510 agar block smears. After 3 years of storage, morphological integrity was found to have been maintained in 72 (71%) of the 102 smears prepared in 2006. Agar block smear preparation preserves the native fungal structures and allows long-term storage and examination of fungal structures embedded in the agar, hence overcoming the major drawbacks of adhesive tape preparation. The major roles of agar block smear should be diagnosis for difficult cases, accurate identification of fungal species for clinical management of patients and epidemiological studies, and long-term storage for transportation of slides and education purposes. PMID:20660221

Agar block smear preparation: a novel method of slide preparation for preservation of native fungal structures for microscopic examination and long-term storage.

PubMed

Woo, Patrick C Y; Ngan, Antonio H Y; Chui, Hon-Kit; Lau, Susanna K P; Yuen, Kwok-Yung

2010-09-01

We describe a novel method of fungal slide preparation named "agar block smear preparation." A total of 510 agar block smears of 25 fungal strains obtained from culture collections, 90 QC fungal strains, and 82 clinical fungal strains from our clinical microbiology laboratory, which included a total of 137 species of yeasts, molds, and thermal dimorphic fungi, were prepared and examined. In contrast to adhesive tape preparation, agar block smears preserved the native fungal structures, such as intact conidiophores of Aspergillus species and arrangements of conidia in Scopulariopsis brevicaulis. Furthermore, agar block smears allowed examination of fungal structures embedded in the agar, such as the ascomata with ascomal hairs in Chaetomium funicola; pycnidium of Phoma glomerata; the intercalary ovoidal chlamydospores arranged in chains of Fusarium dimerum; and the lateral, spherical chlamydospores arranged in pairs of Fusarium solani. After 1 year of storage, morphological integrity was found to have been maintained in 459 (90%) of the 510 agar block smears. After 3 years of storage, morphological integrity was found to have been maintained in 72 (71%) of the 102 smears prepared in 2006. Agar block smear preparation preserves the native fungal structures and allows long-term storage and examination of fungal structures embedded in the agar, hence overcoming the major drawbacks of adhesive tape preparation. The major roles of agar block smear should be diagnosis for difficult cases, accurate identification of fungal species for clinical management of patients and epidemiological studies, and long-term storage for transportation of slides and education purposes.

Efficacy of mealworm and super mealworm larvae probiotics as an alternative to antibiotics challenged orally with Salmonella and E. coli infection in broiler chicks.

PubMed

Islam, Md Manirul; Yang, Chul-Ju

2017-01-01

This study was conducted to evaluate dry mealworm (Tenebrio molitor) (DMLP) and super mealworm (Zophobas morio) (DSMLP) larvae probiotics as alternatives to antibiotics in broiler chicks. A total of 240 one-day old Ross 308 male broiler chicks were randomly assigned to three dietary treatments consisting of ten replications with eight birds each in a completely randomized design. The dietary treatments were, (i) control (basal diet), (ii) 0.4% DMLP (basal diet + 0.4% DMLP, DM basis), and (iii) 0.4% DSMLP (basal diet + 0.4% DSMLP, DM basis). On day one, 1 mL of mixed broth agar consisting of 2.4 × 10 7  cfu Salmonella enteritidis KCTC 2021 and 3.7 × 10 7  cfu Escherichia coli KCTC 2571 was injected orally into each chick. After one week, growth performance, immunity, mortality, internal organ weight, and cecal and fecal microbiota were investigated. Average daily gain ( ADG: ) and average daily feed intake (ADFI) increased, while feed conversion ratio (FCR) (g intake/g gain per bird) decreased in response to DMLP and DSMLP supplementation (P < 0.05). Additionally, mortality decreased (P < 0.05), while IgG and IgA levels increased following DMLP and DSMLP supplementation (P < 0.05). Internal organs remained unaffected, except for a reduced bursa of Fabricius weight in DSMLP supplementation (P < 0.05). Cecal E. coli and Salmonella contents were reduced in DMLP and DSMLP supplementation (P < 0.05), while fecal microbiota contents and pH of cecal and fecal digesta remained unaffected. In conclusion, dietary supplementation with DMLP and DSMLP increased ADG and IgG and IgA levels, while reducing FCR, mortality and cecal E. coli and Salmonella spp. Thus, DMLP and DSMLP can be utilized as an alternative to antibiotics in broiler diets. © 2016 Poultry Science Association Inc.

Comparison of Six Chromogenic Agar Media for the Isolation of a Broad Variety of Non-O157 Shigatoxin-Producing Escherichia coli (STEC) Serogroups

PubMed Central

Verhaegen, Bavo; De Reu, Koen; Heyndrickx, Marc; De Zutter, Lieven

2015-01-01

The isolation of non-O157 STEC from food samples has proved to be challenging. The selection of a suitable selective isolation agar remains problematic. The purpose of this study was to qualitatively and quantitatively evaluate six chromogenic agar media for the isolation of STEC: Tryptone Bile X-glucuronide agar (TBX), Rainbow® Agar O157 (RB), Rapid E. coli O157:H7 (RE), Modified MacConkey Agar (mMac), CHROMagarTM STEC (Chr ST) and chromIDTM EHEC (Chr ID). During this study, 45 E. coli strains were used, including 39 STEC strains belonging to 16 different O serogroups and 6 non-STEC E. coli. All E. coli strains were able to grow on TBX and RB, whereas one STEC strain was unable to grow on Chr ID and a number of other STEC strains did not grow on mMac, CHROMagar STEC and Rapid E. coli O157:H7. However, only the latter three agars were selective enough to completely inhibit the growth of the non-STEC E. coli. Our conclusion was that paired use of a more selective agar such as CHROMagar STEC together with a less selective agar like TBX or Chr ID might be the best solution for isolating non-O157 STEC from food. PMID:26090610

Development of novel agar media for isolating guaiacol producing Alicyclobacillus spp.

PubMed

Chang, S S; Park, S H; Kang, D H

2013-06-03

The purpose of this study is to develop a selective and differential medium (SK2 agar) for isolating guaiacol producing Alicyclobacillus. Forty-one selected dyes and vanillic acid were incorporated in SK agar for screening selective and differential agents. Two guaiacol producing (1016, 1101) and two non-guaiacol producing (19220, C-GD 1-1) Alicyclobacillus isolates were streaked onto media and color differentiation of the isolates was assessed. Among 41 tested dyes, Chrome Azurol S (CAS) allowed color differentiation of the two types of Alicyclobacillus. Colonies of guaiacol producing Alicyclobacillus isolates appeared as dark purple to royal blue color with yellow background, whereas non-guaiacol producing Alicyclobacillus isolates produced cream colored colonies with yellow background. Vanillic acid not only served as a precursor for guaiacol formation but also inhibited non-guaiacol producing Alicyclobacillus. Non-guaiacol producing isolates did not grow on SK agar containing more than 70 ppm vanillic acid, whereas the recovery of guaiacol producing isolates was unaffected. When compared with other Alicyclobacillus isolation media, not only was SK2 agar capable of selectively recovering guaiacol-producing Alicyclobacillus, the degree of growth was also approximately equal if not better than orange serum agar, potato dextrose agar, and K agar. The development of SK2 agar provides the fruit juice industry with an inexpensive, simple to use alternative for the detection of guaiacol producing Alicyclobacillus. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparison of Six Chromogenic Agar Media for the Isolation of a Broad Variety of Non-O157 Shigatoxin-Producing Escherichia coli (STEC) Serogroups.

PubMed

Verhaegen, Bavo; De Reu, Koen; Heyndrickx, Marc; De Zutter, Lieven

2015-06-17

The isolation of non-O157 STEC from food samples has proved to be challenging. The selection of a suitable selective isolation agar remains problematic. The purpose of this study was to qualitatively and quantitatively evaluate six chromogenic agar media for the isolation of STEC: Tryptone Bile X-glucuronide agar (TBX), Rainbow® Agar O157 (RB), Rapid E. coli O157:H7 (RE), Modified MacConkey Agar (mMac), CHROMagarTM STEC (Chr ST) and chromIDTM EHEC (Chr ID). During this study, 45 E. coli strains were used, including 39 STEC strains belonging to 16 different O serogroups and 6 non-STEC E. coli. All E. coli strains were able to grow on TBX and RB, whereas one STEC strain was unable to grow on Chr ID and a number of other STEC strains did not grow on mMac, CHROMagar STEC and Rapid E. coli O157:H7. However, only the latter three agars were selective enough to completely inhibit the growth of the non-STEC E. coli. Our conclusion was that paired use of a more selective agar such as CHROMagar STEC together with a less selective agar like TBX or Chr ID might be the best solution for isolating non-O157 STEC from food.

INTERLABORATORY EVALUATION OF MI AGAR AND THE US ENVIRONMENTAL PROTECTION AGENCY-APPROVED MEMBRANE FILTER METHOD FOR THE RECOVERY OF TOTAL COLIFORMS AND ESCHERICHIA COLI FROM DRINKING WATER

EPA Science Inventory

A new membrane filter (MF) medium, MI agar, recently validated for use in recovering chlorine-damaged total coloiforms (TC) and Escherichia coli from drinking water, was compared to the US Environmental Protection Agency (EPA)-approved MF method(mEndo agar and nutrient agar suppl...

Principal component analysis of normalized full spectrum mass spectrometry data in multiMS-toolbox: An effective tool to identify important factors for classification of different metabolic patterns and bacterial strains.

PubMed

Cejnar, Pavel; Kuckova, Stepanka; Prochazka, Ales; Karamonova, Ludmila; Svobodova, Barbora

2018-06-15

Explorative statistical analysis of mass spectrometry data is still a time-consuming step. We analyzed critical factors for application of principal component analysis (PCA) in mass spectrometry and focused on two whole spectrum based normalization techniques and their application in the analysis of registered peak data and, in comparison, in full spectrum data analysis. We used this technique to identify different metabolic patterns in the bacterial culture of Cronobacter sakazakii, an important foodborne pathogen. Two software utilities, the ms-alone, a python-based utility for mass spectrometry data preprocessing and peak extraction, and the multiMS-toolbox, an R software tool for advanced peak registration and detailed explorative statistical analysis, were implemented. The bacterial culture of Cronobacter sakazakii was cultivated on Enterobacter sakazakii Isolation Agar, Blood Agar Base and Tryptone Soya Agar for 24 h and 48 h and applied by the smear method on an Autoflex speed MALDI-TOF mass spectrometer. For three tested cultivation media only two different metabolic patterns of Cronobacter sakazakii were identified using PCA applied on data normalized by two different normalization techniques. Results from matched peak data and subsequent detailed full spectrum analysis identified only two different metabolic patterns - a cultivation on Enterobacter sakazakii Isolation Agar showed significant differences to the cultivation on the other two tested media. The metabolic patterns for all tested cultivation media also proved the dependence on cultivation time. Both whole spectrum based normalization techniques together with the full spectrum PCA allow identification of important discriminative factors in experiments with several variable condition factors avoiding any problems with improper identification of peaks or emphasis on bellow threshold peak data. The amounts of processed data remain still manageable. Both implemented software utilities are available free of charge from http://uprt.vscht.cz/ms. Copyright © 2018 John Wiley & Sons, Ltd.

A xyloglucan from seeds of the native Brazilian species Hymenaea courbaril for micropropagation of Marubakaido and Jonagored apples.

PubMed

Lima-Nishimura, N; Quoirin, M; Naddaf, Y G; Wilhelm, H M; Ribas, L L F; Sierakowski, M-R

2003-01-01

Xyloglucan was extracted from seeds of Hymenaea courbaril and mixed with agar to prepare a solid culture medium used for micropropagation of the Marubakaido apple rootstock (Malus prunifolia Borkh) and cv. Jonagored (Malus domestica). The performance on gels created from a blend of 0.4%agar and 0.2% xyloglucan (w/v) was compared with that on media gelled with a standard concentration 0.6% (w/v) of agar. The growth of shoots and the multiplication rate were higher on the modified culture medium than on the agar-gelled medium. The occurrence of hyperhydric shoots was lower on the modified medium. In the absence of auxin, shoot rooting reached 70% (Marubakaido) and 66% (Jonagored) on the agar-xyloglucan medium and 6.7% and 10.4%, respectively, on the agar medium. When 0.25 microM indole-3-butyric acid (IBA) was added to both media, the modified medium gave better results in terms of rooting percentage and quality of roots than the agar-gelled medium.

Influence of the extraction process on the rheological and structural properties of agars.

PubMed

Sousa, Ana M M; Borges, João; Silva, A Fernando; Gonçalves, Maria P

2013-07-01

Agars obtained by traditional hot-water (TWE) and microwave-assisted (MAE) extractions were compared in terms of their rheological and physicochemical properties and molecular self-association in solutions of low (0.05%, w/w) and high (1.5%, w/w) polymer concentrations. At low concentration, thin gelled layers were imaged by AFM. Slow or rapid cooling of the solutions influenced structure formation. In each case, TWE and MAE agar structures were different and apparently larger for MAE. At high concentration, progressive structural reinforcement was seen; while TWE agar showed a more open and irregular 3D network, MAE agar gel imaged by cryoSEM was denser and fairly uniform. The rheological (higher thermal stability and consistency) and mechanical (higher gel strength) behaviors of MAE agar seemed consistent with a positive effect of molecular mass and 3,6-anhydro-α-l-galactose content. MAE produced non-degraded agar comparable with commercial ones and if properly monitored, could be a promising alternative to TWE. Copyright © 2013 Elsevier Ltd. All rights reserved.

Amino acid mediated synthesis of silver nanoparticles and preparation of antimicrobial agar/silver nanoparticles composite films.

PubMed

Shankar, Shiv; Rhim, Jong-Whan

2015-10-05

Silver nanoparticles (AgNPs) were synthesized using amino acids (tyrosine and tryptophan) as reducing and capping agents, and they were incorporated into the agar to prepare antimicrobial composite films. The AgNPs solutions exhibited characteristic absorption peak at 420 nm that showed a red shift to ∼434 nm after forming composite with agar. XRD data demonstrated the crystalline structure of AgNPs with dominant (111) facet. Apparent surface color and transmittance of agar films were greatly influenced by the AgNPs. The incorporation of AgNPs into agar did not exhibit any change in chemical structure, thermal stability, moisture content, and water vapor permeability. The water contact angle, tensile strength, and modulus decreased slightly, but elongation at break increased after AgNPs incorporation. The agar/AgNPs nanocomposite films possessed strong antibacterial activity against Listeria monocytogenes and Escherichia coli. The agar/AgNPs film could be applied to the active food packaging by controlling the food-borne pathogens. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation, characterization, and in vitro gastrointestinal digestibility of oil-in-water emulsion-agar gels.

PubMed

Wang, Zheng; Neves, Marcos A; Kobayashi, Isao; Uemura, Kunihiko; Nakajima, Mitsutoshi

2013-01-01

Soybean oil-in-water (O/W) emulsion-agar gel samples were prepared and their digestibility evaluated by using an in vitro gastrointestinal digestion model. Emulsion-agar sols were obtained by mixing the prepared O/W emulsions with a 1.5 wt % agar solution at 60 °C, and their subsequent cooling at 5 °C for 1 h formed emulsion-agar gels. Their gel strength values increased with increasing degree of polymerization of the emulsifiers, and the relative gel strength increased in the case of droplets with an average diameter smaller than 700 nm. Flocculation and coalescence of the released emulsion droplets depended strongly on the emulsifier type; however, the emulsifier type hardly affected the ζ-potential of emulsion droplets released from the emulsion-agar gels during in vitro digestion. The total FFA content released from each emulsion towards the end of the digestion period was nearly twice that released from the emulsion-agar gel, indicating that gelation of the O/W emulsion may have delayed lipid hydrolysis.

Characterization of agar/soy protein biocomposite films: Effect of agar on the extruded pellets and compression moulded films.

PubMed

Garrido, T; Etxabide, A; Guerrero, P; de la Caba, K

2016-10-20

Agar/soy protein biocomposite films were successfully processed by extrusion and compression moulding, obtaining transparent and homogeneous films. The conformational changes occurred during the extrusion process and the effect of agar on the final properties were analyzed. As shown by differential scanning calorimetry (DSC) and specific mechanical energy (SME) values, during the extrusion process protein denatured and unfolded protein chains could interact with agar. These interactions were analyzed by Fourier transform infrared spectroscopy (FTIR) and the secondary structure was determined from the amide I band. Those interactions were supported by the decrease of film solubility. Furthermore, the good compatibility between agar and soy protein was confirmed by the images from scanning electron microscopy (SEM). Copyright © 2016 Elsevier Ltd. All rights reserved.

Kinetics of thermal destruction of Salmonella in ground chicken containing trans-cinnamaldehyde and carvacrol.

PubMed

Juneja, Vijay K; Yadav, Ajit S; Hwang, Cheng-An; Sheen, Shiowshuh; Mukhopadhyay, Sudarsan; Friedman, Mendel

2012-02-01

We investigated the heat resistance of an eight-strain cocktail of Salmonella serovars in chicken supplemented with trans cinnamaldehyde (0 to 1.0%, wt/wt) and carvacrol (0 to 1.0%, wt/wt). Inoculated meat was packaged in bags that were completely immersed in a circulating water bath and held at 55 to 71°C for predetermined lengths of time. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values in chicken, determined by linear regression, were 17.45, 2.89, 0.75, and 0.29 min at 55, 60, 65, and 71°C, respectively (z = 9.02°C). Using a survival model for nonlinear survival curves, D-values in chicken ranged from 13.52 min (D(1), major population) and 51.99 min (D(2), heat-resistant subpopulation) at 55°C to 0.15 min (D(1)) and 1.49 min (D(2)) at 71°C. When the Salmonella cocktail was in chicken supplemented with 0.1 to 1.0% trans-cinnamaldehyde or carvacrol, D-values calculated by both approaches were consistently less at all temperatures. This observation suggests that the addition of natural antimicrobials to chicken renders Salmonella serovars more sensitive to the lethal effect of heat. Thermal death times from this study will be beneficial to the food industry in designing hazard analysis and critical control point plans to effectively eliminate Salmonella contamination in chicken products used in this study.

Influence of organic supplements on production of shoot and callus biomass and accumulation of bacoside in Bacopa monniera (L.) Pennell.

PubMed

Parale, Anuradha; Barmukh, Rajkumar; Nikam, Tukaram

2010-04-01

Production of valuable secondary metabolites through plant cell or organ culture is the best suited alternative to extraction of whole plant material and to increase production of secondary metabolites in in-vitro systems, feeding precursor or intermediate metabolites is an obvious and popular approach. The present investigation was aimed to study the influence of feeding of organic supplements, glycine (0-125 μM), ferulic acid (0-200 μM), phenylalanine (0-200 μM), α-ketoglutaric acid (0-200 μM) and pyruvic acid (0-200 μM) on production of bacoside-A (a triterpenoid type secondary metabolite responsible for cognition effects) in shoot and callus biomass of Bacopa monniera (L.) Pennell. The shoots were raised in liquid Murashige and Skoog's (MS) medium fortified with 5 μM 6-benzyladenine (BA) and callus biomass on agar solidified MS medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4 -D) in conjunction with 5 μM 1-napthaleneacetic acid (NAA). Among the organic supplements used, 100 μM pyruvic acid effectively enhanced the production of bacoside-A in shoot as well as callus biomass. The bacoside-A content in in-vitro raised shoot biomass was 4.0 and 1.2 times higher as compared to control and shoot biomass of naturally grown plants respectively. Inclusion of pyruvic acid in MS medium for in-vitro shoot cultures of B. monniera, can be adapted for enhanced production of bacoside-A.

Acanthamoeba on Sabouraud's agar from a patient with keratitis

PubMed Central

Baradkar, Vasant; Samal, Badhuli; Mali, Swapna A; Kulkarni, Ketaki; Shastri, Jayanthi

2011-01-01

A 25-year-old transgender patient came with complaints of watery discharge, red eye and photophobia in the left eye since 2 days. The patient had a history of wearing colored contact lenses since 4 years and cleaning the lens with tap water. Culture of lenses on Mac Conkey and blood agar yielded Klebsiella pneumoniae and Pseudomonas aeruginosa. Sabouroud's agar showed yeast cells and double-walled cysts of Acanthamoeba species. On further incubation of Sabouroud's agar, the cysts transformed to trophozoites. Parallel results were obtained on tap water agar. The previous therapy of moxifloxacin was changed to local Neosporin application. PMID:23508061

Chocolate agar, a differential medium for gram-positive cocci.

PubMed Central

Gunn, B A

1984-01-01

Reactions incurred on chocolate agar by gram-positive cocci were correlated with species identity. Darkening and clearing of the medium was usually associated with the species Staphylococcus epidermidis, Staphylococcus aureus, Staphylococcus simulans, and Streptococcus faecalis. Yellowing of chocolate agar was associated with alpha-hemolytic species of Streptococcus. The study demonstrated that reactions occurring on chocolate agar are useful in identifying gram-positive cocci. PMID:6490866

Lecythophora hoffmannii isolated from a case of canine osteomyelitis in Japan.

PubMed

Sakaeyama, Shin-Ichi; Sano, Ayako; Murata, Yoshiteru; Kamei, Katsuhiko; Nishimura, Kazuko; Hatai, Kishio

2007-05-01

A 2-year-old spayed female mongrel dog showed claudication with abnormal ossification containing fungal cells detected by biopsy. The dog was treated with ketoconazole and itraconazole perorally for 5 months; however, the osteomyelitis became aggravated, and an amputation from the scapula was performed. The right superficial cervical lymph node became swollen 5 months after the operation. The lymph node contained PAS positive fungal elements and a portion of tissue produced mycelial fungal growth on potato dextrose agar supplemented with chloramphenicol. The culture was identified as Lecythophora hoffmannii based on morphology, physiology and 100% identity in the sequence of the D1/D2 domain of the large subunit ribosomal RNA gene of the fungal species in the GenBank database (accession number AB100627). In addition, the sequence from the present isolate was submitted as AB189164. The isolate showed resistance to antifungal agents, i.e., amphotericin B, 5-FC, fluconazole, itraconazole, miconazole and micafungin. The dog developed cachexia 2 months after the onset of lymphadenopathy, and was euthanized on the 459th day after onset of clinical symptoms. This was the first disseminated case of L. hoffmannii infection in Japan.

Time-lapse analysis of gravitropism in Ceratodon protonemata

NASA Technical Reports Server (NTRS)

Young, J. C.; Sack, F. D.

1992-01-01

The tip cell of the protonema of the moss Ceratodon purpureus (Hedw.) Brid. is negatively gravitropic when grown in the dark on supplemented agar. Gravitropism, plastid distribution, and plastid movement were studied in living cells using time-lapse video microscopy and infrared light. A wrong-way (downward) curvature preceded upward curvature and was detected as early as 2 minutes after reorientation. Upward curvature began 30-45 minutes after reorientation to the horizontal. Cell division temporarily reversed upward curvature, but did not inhibit wrong-way curvature. Since significant amyloplast sedimentation always occurred before the start of upward curvature, it is possible that these amyloplasts function as statoliths for upward curvature. However, no significant amyloplast sedimentation occurred before wrong-way curvature. Thus, this early phase of gravitropism cannot require plastid sedimentation for gravity sensing. Most plastids moved within and between zones, and plastid zonation was highly dynamic. Plastids moved toward the apex and toward the base of the cell at rates much slower than cytoplasmic streaming. Despite the dynamic nature of plastid movement and zonation, during upward curvature the distance between sedimented plastids and the apex stayed constant. Time-lapse analysis has revealed intriguing events not readily seen previously using destructive sampling.

Aciduric Strains of Lactobacillus reuteri and Lactobacillus rhamnosus, Isolated from Human Feces, Have Strong Adhesion and Aggregation Properties.

PubMed

Klopper, Kyle B; Deane, Shelly M; Dicks, Leon M T

2018-03-01

Human feces were streaked onto MRS Agar adjusted to pH 2.5, 3.0, and 6.4, respectively, and medium supplemented with 1.0% (w/v) bile salts. Two aciduric strains, identified as Lactobacillus reuteri HFI-LD5 and Lactobacillus rhamnosus HFI-K2 (based on 16S rDNA and recA sequences), were non-hemolytic and did not hydrolyze mucin. The surface of Lactobacillus reuteri HFI-LD5 cells has a weak negative charge, whereas Lactobacillus rhamnosus HFI-K2 has acidic and basic properties, and produces exopolysaccharides (EPS). None of the strains produce bacteriocins. Both strains are resistant to several antibiotics, including sulfamethoxazole-trimethoprim and sulphonamides. The ability of Lactobacillus reuteri HFI-LD5 and Lactobacillus rhamnosus HFI-K2 to grow at pH 2.5 suggests that they will survive passage through the stomach. EPS production may assist in binding to intestinal mucus, especially in the small intestinal tract, protect epithelial cells, and stimulate the immune system. Lactobacillus reuteri HFI-LD5 and Lactobacillus rhamnosus HFI-K2 may be used as probiotics, especially in the treatment of small intestinal bacterial overgrowth (SIBO).

Wrinkly-Spreader Fitness in the Two-Dimensional Agar Plate Microcosm: Maladaptation, Compensation and Ecological Success

PubMed Central

Spiers, Andrew J.

2007-01-01

Bacterial adaptation to new environments often leads to the establishment of new genotypes with significantly altered phenotypes. In the Wrinkly Spreader (WS), ecological success in static liquid microcosms was through the rapid colonisation of the air-liquid interface by the production of a cellulose-based biofilm. Rapid surface spreading was also seen on agar plates, but in this two-dimensional environment the WS appears maladapted and rapidly reverts to the ancestral smooth (SM)-like colony genotype. In this work, the fitness of WS relative to SM in mixed colonies was found to be low, confirming the WS instability on agar plates. By examining defined WS mutants, the maladaptive characteristic was found to be the expression of cellulose. SM-like revertants had a higher growth rate than WS and no longer expressed significant amounts of cellulose, further confirming that the expression of this high-cost polymer was the basis of maladaptation and the target of compensatory mutation in developing colonies. However, examination of the fate of WS-founded populations in either multiple-colony or single mega-colony agar plate microcosms demonstrated that the loss of WS lineages could be reduced under conditions in which the rapid spreading colony phenotype could dominate nutrient and oxygen access more effectively than competing SM/SM-like genotypes. WS-like isolates recovered from such populations showed increased WS phenotype stability as well as changes in the degree of colony spreading, confirming that the WS was adapting to the two-dimensional agar plate microcosm. PMID:17710140

RAPA: a novel in vitro method to evaluate anti-bacterial skin cleansing products.

PubMed

Ansari, S A; Gafur, R B; Jones, K; Espada, L A; Polefka, T G

2010-04-01

Development of efficacious anti-bacterial skin cleansing products has been limited by the availability of a pre-clinical (in vitro) method to predict clinical efficacy adequately. We report a simple and rapid method, designated as rapid agar plate assay (RAPA), that uses the bacteriological agar surface as a surrogate substrate for skin and combines elements of two widely used in vivo (clinical) methods (Agar Patch and Cup Scrub). To simulate the washing of the human hand or forearm skin with the test product, trypticase soy agar plates were directly washed with the test product and rinsed under running tap water. After air-drying the washed plates, test bacteria (Staphylococcus aureus or Escherichia coli) were applied and the plates were incubated at 37 degrees C for 18-24 h. Using S. aureus as the test organism, anti-bacterial bar soap containing triclocarbanilide showed a strong linear relationship (R(2) = 0.97) between bacterial dose and their per cent reduction. A similar dose-response relationship (R(2) = 0.96) was observed for anti-bacterial liquid hand soap against E. coli. RAPA was able to distinguish between anti-bacterial products based on the nature and level of actives in them. In limited comparative tests, results obtained by RAPA were comparable with the results obtained by clinical agar patch and clinical cup scrub methods. In conclusion, RAPA provides a simple, rugged and reproducible in vitro method for testing the relative efficacy of anti-bacterial skin cleansing products with a likelihood of comparable clinical efficacy. Further testing is warranted to improve the clinical predictability of this method.

Comparison of four chromogenic media and Hektoen agar for detection and presumptive identification of Salmonella strains in human stools.

PubMed

Perez, J M; Cavalli, P; Roure, C; Renac, R; Gille, Y; Freydiere, A M

2003-03-01

Several chromogenic media have been developed to enhance the specificity of Salmonella detection. We compared the performance of four commercial chromogenic media-namely, ABC medium (Lab M. Ltd., Bury, United Kingdom), COMPASS Salmonella agar (Biokar Diagnostics, Beauvais, France), CHROMagar Salmonella agar (CHROMagar Company, Paris, France), and SM ID agar (bioMerieux, Marcy l'Etoile, France)-with conventional Hektoen medium. Nine hundred sixteen stool samples from inpatients at three hospitals were cultured, in parallel, on the five media, both by direct inoculation and after selective enrichment in selenite broth. Sixty-four Salmonella strains with 12 serotypes were isolated on at least one medium. After 48 h of incubation, sensitivity before and after enrichment was 62.5 and 89.1% with ABC medium, 77.1 and 93.8% with COMPASS agar, 66.7 and 89.1% with CHROMagar, 68.8 and 85.9% with SM ID agar, and 85.4 and 98.4% with Hektoen agar, respectively. Broth enrichment and prolonged incubation (48 versus 24 h) increased the sensitivity of all five media. Only one strain was not isolated on Hektoen agar. The number of false-positive isolates was higher with all five media after enrichment in selenite broth and after incubation for 48 h compared to 24 h. The specificity of the four chromogenic media was better than 91% after incubation for 24 h (77.7% with Hektoen agar) and better than 84% after incubation for 48 h (74.8% with Hektoen agar). This higher specificity reduces the need for confirmatory tests, thereby cutting technical time and reagent requirements. Both COMPASS agar and CHROMagar Salmonella, which after simple additional tests showed close efficiencies (96 and 97%, respectively), can be recommended as single-plate media of choice for the detection and presumptive identification of salmonellae in stools.

Diagnostic value of morphological, physiological and biochemical tests in distinguishing Trichophyton rubrum from Trichophyton mentagrophytes complex.

PubMed

Ates, Aylin; Ozcan, Kadri; Ilkit, Macit

2008-12-01

The two most frequently encountered dermatophyte etiologic agents of glabrous skin and nail dermatophytoses are Trichophyton rubrum and T. mentagrophytes. This study was aimed to discuss the efficacy of morphological, physiological and biochemical diagnostic tests commonly used in the identification of T. rubrum and members of the T. mentagrophytes complex. In this study, we evaluated; hydrolysis of urea in broth and on urea agar slants and Petri plates incubated at 22 degrees C, 28 degrees C and 37 degrees C, in vitro hair perforation (blond child, sheep and goat hair), pigment production on cornmeal dextrose agar (CMDA) and bromcresol purple-milk solids-glucose agar (BCP-MS-G), Tween opacity, sorbitol assimilation, and salt tolerance. Additionally, the production of micro- and macroconidia was investigated by using brain heart infusion agar (BHIA), Christensen's urea agar in Petri plates (UPA), CMDA, Lowenstein-Jensen agar (LJA), malt extract agar, oatmeal agar, Oxoid chromogenic Candida agar, and potato dextrose agar. All cultures were incubated at 28 degrees C, and conidial production was compared on days 5, 10 and 15. It was found that the urea hydrolysis test yielded more rapid and significant results when urea medium was prepared in Petri plates and incubated at 28 degrees C (P<0.01). LJA supported the highest production of microconidia after 15 days (P<0.001). Additionally, it was found that T. rubrum strains produced red pigment on CMDA (P<0.01) and BCP-MS-G, while strains of the T. mentagrophytes species complex did not. A special algorithm containing the various test procedures employed in these studies is presented which was found to be useful in the differentiation of T. rubrum strains from T. mentagrophytes complex. Our results revealed that UPA, CMDA, BCP-MS-G, LJA, and BHIA may be used as common mycological agars in routine practice.

Candida krusei form mycelia along agar surfaces towards each other and other Candida species.

PubMed

Fleischmann, Jacob; Broeckling, Corey D; Lyons, Sarah

2017-03-11

Candida krusei has been known to exhibit communal interactions such as pellicle formation and crawling out of nutritional broth. We noticed another possible interaction on agar surfaces, where C. krusei yeast cells formed mycelia along agar surfaces toward each other. We report here the results of experiments to study this interaction. When C.krusei yeast cells are plated in parallel streaks, they form mycelia along agar surfaces toward other yeasts. They also detect the presence of Candida albicans and Candida glabrata across agar surfaces, while the latter two react neither to their own kind, nor to C. krusei. Secreted molecule(s) are likely involved as C.krusei does not react to heat killed C. krusei. Timing and rate of mycelia formation across distances suggests that mycelia start forming when a secreted molecule(s) on agar surface reaches a certain concentration. We detected farnesol, tyrosol and tryptophol molecules that may be involved with mycelial formation, on the agar surfaces between yeast streaks. Unexpectedly the amounts detected between streaks were significantly higher than would have expected from additive amounts of two streaks. All three Candida species secreted these molecules. When tested on agar surface however, none of these molecules individually or combined induced mycelia formation by C. krusei. Our data confirms another communal interaction by C. krusei, manifested by formation of mycelia by yeast cells toward their own kind and other yeasts on agar surfaces. We detected secretion of farnesol, tyrosol and tryptophol by C. krusei but none of these molecules induced this activity on agar surface making it unlikely that they are the ones utilized by this yeast for this activity.

Research on Candida dubliniensis in a Brazilian yeast collection obtained from cardiac transplant, tuberculosis, and HIV-positive patients, and evaluation of phenotypic tests using agar screening methods.

PubMed

Ribeiro, Patrícia Monteiro; Querido, Silvia Maria Rodrigues; Back-Brito, Graziela Nueremberg; Mota, Adolfo José; Koga-Ito, Cristiane Yumi; Jorge, Antonio Olavo Cardoso

2011-09-01

The aim of this study was to research Candida dubliniensis among isolates present in a Brazilian yeast collection and to evaluate the main phenotypic methods for discrimination between C. albicans and C. dubliniensis from oral cavity. A total of 200 isolates, presumptively identified as C. albicans or C. dubliniensis obtained from heart transplant patients under immunosuppressive therapy, tuberculosis patients under antibiotic therapy, HIV-positive patients under antiretroviral therapy, and healthy subjects, were analyzed using the following phenotypic tests: formation and structural arrangement of chlamydospores on corn meal agar, casein agar, tobacco agar, and sunflower seed agar; growth at 45 °C; and germ tube formation. All strains were analyzed by polymerase chain reaction (PCR). In a preliminary screen for C. dubliniensis, 48 of the 200 isolates on corn meal agar, 30 of the 200 on casein agar, 16 of the 200 on tobacco agar, and 15 of the 200 on sunflower seed agar produced chlamydoconidia; 27 of the 200 isolates showed no or poor growth at 45 °C. All isolates were positive for germ tube formation. These isolates were considered suggestive of C. dubliniensis. All of them were subjected to PCR analysis using C. dubliniensis-specific primers. C. dubliniensis isolates were not found. C. dubliniensis isolates were not recovered in this study done with immunocompromised patients. Sunflower seed agar was the medium with the smallest number of isolates of C. albicans suggestive of C. dubliniensis. None of the phenotypic methods was 100% effective for discrimination between C. albicans and C. dubliniensis. Copyright © 2011 Elsevier Inc. All rights reserved.

Isolation of Cryptococcus neoformans and other opportunistic fungi from pigeon droppings.

PubMed

Soltani, Maryam; Bayat, Mansour; Hashemi, Seyed J; Zia, Mohammadali; Pestechian, Nader

2013-01-01

Invasive fungal infections cause considerable morbidity and mortality in immunocompromised hosts. Pigeon droppings could especially be a potential carrier in the spread of pathogenic yeasts and mold fungi into the environment. The objective of this study was to isolation of Cryptococcus neoformans and other opportunistic fungi from pigeon droppings. One hundred twenty samples of pigeon droppings were suspended 1:10 in saline solution and then cultured. Identification of C. neoformans was performed on bird seed agar, presence of a capsule on India ink preparation, urease production on urea agar medium and RapID yeast plus system. The identification of candida species was based on micro-morphological analysis on corn meal-Tween 80 agar, RapID yeast plus system and growth in CHROMagar candida. The identification of other fungi was based on macromorphologic, microscopic, biochemical and physiological characteristics. The highest frequency of yeasts and mold fungi were observed in Candida albicans 6.6% and Penicillium spp. 25%. The frequency rate of C. neoformans isolation was 2.5%. Several types of fungi are present in pigeon droppings that can spread in environment and transmit to children and elderly as well as immunocompromised patients who are at increased risk of contracting opportunistic diseases.

High solid loading aqueous base metal/ceramic feedstock for injection molding

NASA Astrophysics Data System (ADS)

Behi, Mohammad

2001-07-01

Increasing volume fraction of metal powder in feedstock provided lower shrinkage. Reduction of the shrinkage results in better dimensional precision. The rheology of the feedstock material plays an important role to allowing larger volume fractions of the metal powder to be incorporated in the feedstock formulations. The viscosity of the feedstock mainly depends on the binder viscosity, powder volume fraction and characteristics of metal powder. Aqueous polysaccharide agar was used as a baseline binder system for this study. The effect of several gel-strengthening additives on 1.5wt% and 2wt% agar gel was evaluated. A new gel-strengthening additive was found to be the most effective among the others. The effect of other additives such as glucose, sucrose and fructose on viscosity of baseline binder and feedstock was investigated. Two new agar based binder compositions were developed. The use of these new binder formulations significantly improved the volume fraction of the metal powder, the stability of the feedstock, and reduced the final shrinkage of the molded articles. Two types of 17-4PH stainless steel metal powders, one gas atomized and, the other water atomized, were used for this research.

Active systems based on silver-montmorillonite nanoparticles embedded into bio-based polymer matrices for packaging applications.

PubMed

Incoronato, A L; Buonocore, G G; Conte, A; Lavorgna, M; Nobile, M A Del

2010-12-01

Silver-montmorillonite (Ag-MMT) antimicrobial nanoparticles were obtained by allowing silver ions from nitrate solutions to replace the Na(+) of natural montmorillonite and to be reduced by thermal treatment. The Ag-MMT nanoparticles were embedded in agar, zein, and poly(ε-caprolactone) polymer matrices. These nanocomposites were tested in vitro with a three-strain cocktail of Pseudomonas spp. to assess antimicrobial effectiveness. The results indicate that Ag-MMT nanoparticles embedded into agar may have antimicrobial activity against selected spoilage microorganisms. No antimicrobial effects were recorded with active zein and poly(ε-caprolactone). The water content of the polymeric matrix was the key parameter associated with antimicrobial effectiveness of this active system intended for food packaging applications.

Evaluation of Cariogenic Bacteria

PubMed Central

Nishikawara, Fusao; Nomura, Yoshiaki; Imai, Susumu; Senda, Akira; Hanada, Nobuhiro

2007-01-01

Objectives The evaluation of Mutans streptococci (MS) is one of the index for caries risk. DentocultTM and CRTTM are commercial kits to detect and evaluate MS, conveniently. However, the evaluation of MS has also been carried out simply using an instruction manual. But the instruction manual is not easy to use for evaluation of MS. The aim of this study was to examine the utility of modified Mitis-Salivalius Bacitracin (MSB) agar medium compared with MSB agar medium and commercial kits, and to establish a convenient kit (mMSB-kit) using modified MSB agar. Methods The MS in stimulated saliva from 27 subjects were detected by MSB, modified MSB agar medium and commercial kits. Laboratory and clinically isolated strains of MS were similarly evaluated. The ratios of MS in detected bacteria were compared by ELISA. Results The scores using an mMSB-kit on the basis of modified MSB agar medium were tabulated. Saliva samples showed different levels of MS between culture methods and the commercial kit. Some samples which were full of MS were not detected by the commercial kit. The detection of MS by modified MSB agar medium and mMSB-kit were significantly higher when compared with MSB agar medium,CRTTM, (P< .01) and Dentocult SMTM (P<.05). Conclusion The sensitivity for detection of MS is higher for modified MSB agar medium when compared with MSB agar medium. The mMSB-kit can be used simply, and can be an important contributor for the evaluation of MS as a caries risk factor. PMID:19212495

First Isolation of carbon dioxide-dependent Proteus mirabilis from an uncomplicated cystitis patient with Sjögren's syndrome.

PubMed

Oana, Kozue; Yamaguchi, Michiko; Nagata, Mika; Washino, Kei-Ichi; Akahane, Takayuki; Takamatsu, Yu-Uki; Tsutsui, Chie; Matsumoto, Takehisa; Kawakami, Yoshiyuki

2013-01-01

An uncomplicated cystitis caused by CO2-dependent Proteus mirabilis was observed in a 64-year-old Japanese female patient with Sjögren's syndrome in the Aomori Kyoritsu Hospital, Aomori, Japan. The initial P. mirabilis isolate came from a midstream urine specimen containing large numbers of Gram-negative, rod-shaped organisms that failed to grow on both Drigalski agar and sheep blood agar incubated in ambient air. The organism did grow when the urine was cultured overnight on blood agar under anaerobic conditions. Hence, we believed that the organism was an anaerobe. Further investigation revealed that the isolate grew on sheep blood agar along with swarming when the atmospheric CO2 concentrations were increased to 5%. Initially, we failed to characterize or identify the P. mirabilis isolate or determine its antimicrobial susceptibilities using the MicroScan WalkAway-40 System because the isolate did not grow in the system. However, the isolate was subsequently identified as P. mirabilis based on its morphological, cultural, and biochemical properties by using the commercially available kit systems, Quick ID-GN and ID-Test EB-20. This identification of the isolate was confirmed by sequencing the 16S rRNA gene of the organism. To our knowledge, this is the first clinical isolation of capnophilic P. mirabilis.

New medium for rapid screening and enumeration of Clostridium perfringens in foods.

PubMed Central

Erickson, J E; Deibel, R H

1978-01-01

A rapid and sensitive procedure for estimating low numbers of Clostridium perfringens has been investigated and compared to methods used currently in the food industry. The new liquid medium, RPM (rapid perfringens medium), was compared with sulfite-polymyxin-sulfadiazine agar and tryptose-sulfite-cycloserine agar in recovery studies with naturally contaminated and with inoculated foods. The medium consists of a mixture of litmus milk and fluid thioglycolate medium fortified with glucose, peptone, gelatin, yeast extract, sodium chloride, and ferrous sulfate. Selectivity is based on an antibiotic system (polymyxin B sulfate and neomycin sulfate) incorporated into the medium, coupled with an incubation temprature of 46 to 48 degrees C for 24 h. Tubes were scored as positive if a stormy fermentation was observed. All tubes demonstrating stormy fermentation were confirmed as containing C. perfringens. Of a total of 774 naturally contaminated food samples, 546 samples (71%) were found to contain C. perfringens with RPM, whereas only 168 (22%) of the samples were positive using sulfite-polymyxin-sulfadiazine agar. C. perfringens was isolated from 71% of 85 other samples using RPM as compared to 14% with tryptose-sulfite-cycloserine agar. Enumeration studies on 14 individual samples using the most probable number technique also demonstrated greater sensitivity with RPM. PMID:213019

Spaceflight exposure effects on transcription, activity, and localization of alcohol dehydrogenase in the roots of Arabidopsis thaliana.

PubMed Central

Porterfield, D M; Matthews, S W; Daugherty, C J; Musgrave, M E

1997-01-01

Although considerable research and speculation have been directed toward understanding a plant's perception of gravity and the resulting gravitropic responses, little is known about the role of gravity-dependent physical processes in normal physiological function. These studies were conducted to determine whether the roots of plants exposed to spaceflight conditions may be experiencing hypoxia. Arabidopsis thaliana (L.) Heynh. plants were grown in agar medium during 6 or 11 d of spaceflight exposure on shuttle missions STS-54 (CHROMEX-03) and STS-68 (CHROMEX-05), respectively. The analysis included measurement of agar redox potential and root alcohol dehydrogenase (ADH) activity, localization, and expression. ADH activity increased by 89% as a result of spaceflight exposure for both CHROMEX-03 and -05 experiments, and ADH RNase protection assays revealed a 136% increase in ADH mRNA. The increase in ADH activity associated with the spaceflight roots was realized by a 28% decrease in oxygen availability in a ground-based study; however, no reduction in redox potential was observed in measurements of the spaceflight bulk agar. Spaceflight exposure appears to effect a hypoxic response in the roots of agar-grown plants that may be caused by changes in gravity-mediated fluid and/or gas behavior. PMID:9085569

Spaceflight exposure effects on transcription, activity, and localization of alcohol dehydrogenase in the roots of Arabidopsis thaliana

NASA Technical Reports Server (NTRS)

Porterfield, D. M.; Matthews, S. W.; Daugherty, C. J.; Musgrave, M. E.

1997-01-01

Although considerable research and speculation have been directed toward understanding a plant's perception of gravity and the resulting gravitropic responses, little is known about the role of gravity-dependent physical processes in normal physiological function. These studies were conducted to determine whether the roots of plants exposed to spaceflight conditions may be experiencing hypoxia. Arabidopsis thaliana (L.) Heynh. plants were grown in agar medium during 6 or 11 d of spaceflight exposure on shuttle missions STS-54 (CHROMEX-03) and STS-68 (CHROMEX-05), respectively. The analysis included measurement of agar redox potential and root alcohol dehydrogenase (ADH) activity, localization, and expression. ADH activity increased by 89% as a result of spaceflight exposure for both CHROMEX-03 and -05 experiments, and ADH RNase protection assays revealed a 136% increase in ADH mRNA. The increase in ADH activity associated with the spaceflight roots was realized by a 28% decrease in oxygen availability in a ground-based study; however, no reduction in redox potential was observed in measurements of the spaceflight bulk agar. Spaceflight exposure appears to effect a hypoxic response in the roots of agar-grown plants that may be caused by changes in gravity-mediated fluid and/or gas behavior.

The effect of urea and ammonia treatments on the survival of Salmonella spp. and Yersinia enterocolitica in pig slurry.

PubMed

Bolton, D J; Ivory, C; McDowell, D A

2013-01-01

The objective of this study was to investigate the survival of Salmonella and Yersinia enterocolitica strains in pig slurry and evaluate urea and ammonia as disinfection strategies. Salmonella Anatum, Salmonella Derby, Salmonella Typhimurium DT19 and Y. enterocolitica bioserotypes 4, O:3, 2, O:5,27 and 1A, O:6,30 were selectively marked by insertion of the plasmid, pGLO encoding for green fluorescent protein and for ampicillin resistance. Strain cocktails were inoculated into fresh pig slurry (control), slurry treated with urea [final concentration 2% w/w, (0.33 mol l(-1) )] and slurry treated with ammonia [final concentration 0.5% w/w, (0.3 mol l(-1) )] and stored at 4, 14 and 25°C. Bacterial counts were determined at regular intervals on xylose lysine deoxycholate agar (XLD), and XLD supplemented with ampicillin (0.1 mg ml(-1) ) and arabinose (0.6 mg ml(-1) ) for Salmonella and cefsulodin-irgasan-novobiocin agar (CIN) and CIN supplemented with ampicillin and arabinose for Y. enterocolitica. The pH of the control-, urea- and ammonia-treated samples ranged from 7.1 to 7.7, 8.8 to 8.9 and 8.0 to 8.3, respectively. Salmonella D(4) values ranged from 2.71 to 21.29 days, D(14) values from 2.72 to 11.62 days and D(25) values from 1.76 to 6.85 days. The equivalent D values ranges for the Y. enterocolitica strains were 3.7-19.23, 1.8-16.67 and 1.63-7.09 days, respectively. Treatment significantly (P < 0.01) affected D values with control > ammonia > urea, as did incubation temperature; 4 > 14 > 25°C. Urea and to a lesser extent ammonia may be used to disinfect Salmonella- and/or Y. enterocolitica-contaminated pig slurry, decreasing the storage time required while increasing its fertilizer value. This study presents data supporting the treatment of pig slurry to kill important zoonotic agents, thereby reducing environmental contamination, cross-infection of other animals and decreasing zoonotic disease in the food chain. © 2012 The Society for Applied Microbiology.

Use of agar/glycerol and agar/glycerol/water as a translucent brain simulant for ballistic testing.

PubMed

Falland-Cheung, Lisa; Waddell, J Neil; Lazarjan, Milad Soltanipour; Jermy, Mark C; Winter, Taylor; Tong, Darryl; Brunton, Paul A

2017-01-01

The suitability of agar/glycerol/water and agar/glycerol mixtures as brain simulants was investigated. Test specimens (n=15) (50x27×37mm) were fabricated for these different mixtures and conditioned to 12°C, 22°C, and 26°C prior to testing. For comparison, fresh deer brain specimens (n=20) were sourced and prepared to the same dimensions as the agar/glycerol(/water) mixtures and conditioned to 12°C and 37°C. High impact tests were carried out with a 0.22-caliber air rifle pellet and a high-speed camera was used to record the projectile as it passed through the specimens, allowing for energy loss and vertical displacement velocity calculation. Although the agar/glycerol/water mixture presented with similar vertical expansion and contraction of the specimens to the warm and cold deer brains, a two-fold decrease of the vertical expansion and contraction was noticed with the agar/glycerol specimens. Also considerably less extrusion of this mixture out of the exit and entry sides after specimen penetration was observed. Of the simulants tested, agar/glycerol/water was the most suitable brain simulant for ballistic testing and impact studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detection of Agar, by Analysis of Sugar Markers, Associated with Bacillus Anthracis Spores, After Culture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wunschel, David S.; Colburn, Heather A.; Fox, Alvin

2008-08-01

Detection of small quantities of agar associated with spores of Bacillus anthracis could provide key information regarding its source or growth characteristics. Agar, widely used in growth of bacteria on solid surfaces, consists primarily of repeating polysaccharide units of 3,6-anhydro-L-galactose (AGal) and galactose (Gal) with sulfated and O-methylated galactoses present as minor constituents. Two variants of the alditol acetate procedure were evaluated for detection of potential agar markers associated with spores. The first method employed a reductive hydrolysis step, to stabilize labile anhydrogalactose, by converting to anhydrogalactitol. The second eliminated the reductive hydrolysis step simplifying the procedure. Anhydrogalactitol, derived frommore » agar, was detected using both derivatization methods followed by gas chromatography-mass spectrometry (GC-MS) analysis. However, challenges with artefactual background (reductive hydrolysis) or marker destruction (hydrolysis) lead to the search for alternative sugar markers. A minor agar component, 6-O-methyl galactose (6-O-M gal), was readily detected in agar-grown but not broth-grown bacteria. Detection was optimized by the use of gas chromatography-tandem mass spectrometry (GC-MS-MS). With appropriate choice of sugar marker and analytical procedure, detection of sugar markers for agar has considerable potential in microbial forensics.« less

Current knowledge on agarolytic enzymes and the industrial potential of agar-derived sugars.

PubMed

Yun, Eun Ju; Yu, Sora; Kim, Kyoung Heon

2017-07-01

Agar is a major cell wall carbohydrate of red macroalgae (Rhodophyta). Sugars derived from agar, such as agarooligosaccharides (AOSs), neoagarooligosaccharides (NAOSs), neoagarobiose (NAB), and 3,6-anhydro-L-galactose (L-AHG), possess various physiological activities. These agar-derived sugars can be produced by hydrolysis using chemicals or agarolytic enzymes. Despite the industrial potential of agar-derived sugars, their application has been hampered mainly due to the absence of efficient processes for the liquefaction and saccharification of agar. In this review, we have focused on strategies for producing high value-added sugars from agarose via chemical or enzymatic liquefaction and enzymatic saccharification. The liquefaction of agarose is a key step for preventing gelling and increasing the solubility of agarose in water by prehydrolyzing agarose into AOSs or NAOSs. For the industrial use of agar-derived sugars, AOS, NAOS, NAB, and L-AHG can be used as functional biomaterials owing to their physiological activities such as antiinflammation, skin whitening, and moisturizing. Recently, it was reported that AHG could be considered as a new anticariogenic sugar to replace xylitol. This review provides a comprehensive overview of processes for the hydrolysis of agar or agarose to produce high value-added sugars and the industrial application of these sugars.

Optimization of the Agar-gel Method for Isolation of Migrating Ascaris suum Larvae From the Liver and Lungs of Pigs

PubMed Central

Saeed, I; Roepstorff, A; Rasmussen, T; Høg, M; Jungersen, G

2001-01-01

Experiments on use of an agar-gel method for recovery of migrating Ascaris suum larvae from the liver and lungs of pigs were conducted to obtain fast standardized methods. Subsamples of blended tissues of pig liver and lungs were mixed with agar to a final concentration of 1% agar and the larvae allowed to migrate out of the agar-gel into 0.9% NaCl at 38°C. The results showed that within 3 h more than 88% of the recoverable larvae migrated out of the liver agar-gel and more than 83% of the obtained larvae migrated out of the lung agar-gel. The larvae were subsequently available in a very clean suspension which reduced the sample counting time. Blending the liver for 60 sec in a commercial blender showed significantly higher larvae recovery than blending for 30 sec. Addition of gentamycin to reduce bacterial growth during incubation, glucose to increase larval motility during migration or ice to increase sedimentation of migrated larvae did not influence larvae recovery significantly. PMID:11503373

Application of Fourier Transform Infrared (FTIR) Spectroscopy for Rapid Detection of Fumonisin B2 in Raisins.

PubMed

Heperkan, Dilek; Gökmen, Ece

2016-07-01

The aim of this study was to investigate the potential use of FTIR spectroscopy as a rapid screening method to detect fumonisin produced by Aspergillus niger. A. niger spore suspensions isolated from raisins were inoculated in Petri dishes prepared with sultana raisin or black raisin extracts containing agar and malt extract agar (MEA). After 9 days of incubation at 25°C, fumonisin B2 (FB2) production on each agar plate was determined by subjecting the agar plugs to IR spectroscopy. The presence of amino group (at 1636-1639 cm(-1)) was especially indicative of fumonisin production in MEA and the raisin extracts containing agar. The results were confirmed by HPLC analysis of the agar sample extracts after immunoaffinity column cleanup. It was determined that A. niger produced more FB2 in sultana raisins than in MEA, with no FB2 being produced in black raisin extract agar. This study demonstrated that proper sample preparation procedure followed by FTIR analysis is a useful technique for identifying toxigenic molds and their mycotoxin production in agricultural commodities.

An extension of the Coconut Cream Agar method to screen Penicillium citrinum isolates for citrinin production.

PubMed

Mohamed, S; Flint, S; Palmer, J; Fletcher, G C; Pitt, J I

2013-09-01

A simple and rapid screening method was developed for the detection of citrinin in fungal cultures using Coconut Cream Agar (CCA) described previously for detecting aflatoxin and ochratoxin A. Fifteen isolates of Penicillium citrinum were inoculated onto CCA and incubated at 25 and 30°C for 10 days. All isolates produced a distinct yellow green fluorescence on CCA when the reverse side of the agar plates were viewed under long wavelength UV light. Detection was optimal at 25°C after four to 5 days of incubation. Isolates positive by the CCA method also tested positive for citrinin production by the TLC agar plug method after growth on CCA, Czapek yeast extract agar and yeast extract sucrose agar. Control cultures were negative by both methods, indicating that the CCA Petri dish method was suitable for screening cultures for citrinin production. © 2013 The Society for Applied Microbiology.

Green synthesis of gold nanoparticles of different sizes and shapes using agar-agar water solution and femtosecond pulse laser irradiation

NASA Astrophysics Data System (ADS)

Almeida de Matos, Ricardo; da Silva Cordeiro, Thiago; Elgul Samad, Ricardo; Dias Vieira, Nilson; Coronato Courrol, Lilia

2012-11-01

We report a method to create gold nanoparticles of different sizes and shapes using agar-agar water solution and irradiation with light from a xenon lamp, followed by ultrashort laser pulses. No additives, such as solvents, surfactants or reducing agents, were used in the procedure. Laser irradiation (laser ablation) was important to the reduction of the nanoparticles diameter and formation of another shapes. Distilled water was used as solvent and agar-agar (hydrophilic colloid extracted from certain seaweeds) was important for the stabilization of gold nanoparticles, avoiding their agglomeration. The formation of gold nanoparticles was confirmed with ultraviolet-visible absorption and TEM microscopy. The gold nanoparticles acquired spherical, prism, and rod shapes depending on the laser parameters. Variation of laser irradiation parameters as pulse energy, irradiation time and repetition rate was assessed. The relevant mechanisms contributing for the gold nanoparticles production are discussed.

Influence of Albizia lebbeck Saponin and Its Fractions on In Vitro Gas Production Kinetics, Rumen Methanogenesis, and Rumen Fermentation Characteristics.

PubMed

Sirohi, Sunil Kumar; Goel, Navneet; Singh, Nasib

2014-01-01

The present study was undertaken to investigate the effect of crude seed powder (CSP) and gross saponins extract (GSE) of seeds of Albizia lebbeck on antimicrobial activity by taking two Gram-positive (Staphylococcus aureus and Bacillus cereus), two Gram-negative (Escherichia coli and Salmonella Typhi) bacteria, and two fungi species (Aspergillus niger and Candida butyric) were taken at 25, 50, 100, 250, and 500 µg levels using agar well diffusion method. Zone of inhibition was increased with increasing of concentration of CSP and saponins which indicates that Gram-negative bacteria (E. coli), Gram-positive bacteria (B. cereus), and A. niger were significantly susceptible to inhibition. Another experiment was conducted to study the effect of GSE and saponins fraction A and B of A. lebbeck supplementation at 6% on DM basis on methane production and other rumen fermentation parameters using in vitro gas production test, by taking three different type diets, that is, high fiber diet (D1, 60R : 40C), medium fiber diet (D2, 50R : 50C), and low fiber diet (D3, 40R : 60C). Significant (P ≤ 0.05) increase was seen in IVDMD, methane production; however ammonia nitrogen concentration decreased as compared to control. The methane production was reduced in a range between 12 and 49% by saponin supplemented diets except in case of GSE in D2. Sap A showed the highest methane reduction per 200 mg of truly digested substrate (TDS) than other treatment groups. Results in relation with quantification of methanogens and protozoa by qPCR indicated the decreasing trend with saponins of A. lebbek in comparison with control except total methanogen quantified using mcr-A based primer.

Influence of Albizia lebbeck Saponin and Its Fractions on In Vitro Gas Production Kinetics, Rumen Methanogenesis, and Rumen Fermentation Characteristics

PubMed Central

Sirohi, Sunil Kumar; Goel, Navneet; Singh, Nasib

2014-01-01

The present study was undertaken to investigate the effect of crude seed powder (CSP) and gross saponins extract (GSE) of seeds of Albizia lebbeck on antimicrobial activity by taking two Gram-positive (Staphylococcus aureus and Bacillus cereus), two Gram-negative (Escherichia coli and Salmonella Typhi) bacteria, and two fungi species (Aspergillus niger and Candida butyric) were taken at 25, 50, 100, 250, and 500 µg levels using agar well diffusion method. Zone of inhibition was increased with increasing of concentration of CSP and saponins which indicates that Gram-negative bacteria (E. coli), Gram-positive bacteria (B. cereus), and A. niger were significantly susceptible to inhibition. Another experiment was conducted to study the effect of GSE and saponins fraction A and B of A. lebbeck supplementation at 6% on DM basis on methane production and other rumen fermentation parameters using in vitro gas production test, by taking three different type diets, that is, high fiber diet (D1, 60R : 40C), medium fiber diet (D2, 50R : 50C), and low fiber diet (D3, 40R : 60C). Significant (P ≤ 0.05) increase was seen in IVDMD, methane production; however ammonia nitrogen concentration decreased as compared to control. The methane production was reduced in a range between 12 and 49% by saponin supplemented diets except in case of GSE in D2. Sap A showed the highest methane reduction per 200 mg of truly digested substrate (TDS) than other treatment groups. Results in relation with quantification of methanogens and protozoa by qPCR indicated the decreasing trend with saponins of A. lebbek in comparison with control except total methanogen quantified using mcr-A based primer. PMID:24977047

Characterization of an extracellular lipase by Pseudomonas koreensis BK-L07 isolated from soil.

PubMed

Anbu, Periasamy

2014-01-01

Screening using spirit blue agar revealed that strain BK-L07 had the highest lipase activity. Furthermore, the isolated strain was identified as Pseudomonas sp. based on morphological, physiological, biochemical, and molecular analyses. The 16S rRNA gene sequence of strain BK-L07 shared a high similarity with that of Pseudomonas koreensis (99%). The nutritional conditions and physicochemical properties were influenced by P. koreensis BK-L07. The maximum lipase production was obtained in tryptic soy broth medium at pH 8.0 and a temperature of 25°C after 36 hr of incubation. In addition, the lipase activity was determined using different carbon sources and lipase inducers. The lipase production was greatest when 1% maltose was used as the carbon source and olive oil was used as the lipase inducer. The lipase production was significantly increased approximately threefold in the optimized medium when compared with the original medium. Further, the lipase was purified by ammonium sulfate precipitation and gel filtration chromatography with a purification yield of 10.8%. The molecular mass of lipase was 45 kDa. The optimum temperature and pH were 40°C and 8.0, respectively. The enzyme was stable up to 50°C and at pH from 7 to 9. In addition, the enzyme activity was stimulated by MgSO4 and completely inhibited by ethylenediamine tetraacetic acid (EDTA), indicating the metalloenzyme type. The lipase activity was toward medium to long chain length of fatty acids (C10 to C18). Supplemental materials are available for this article. Go to the publisher's online edition of Preparative Biochemistry and Biotechnology to view the supplemental file.

Identification of coryneform Actinomyces neuii by MALDI-TOF MS: 5 case reports and review of literature.

PubMed

De Vreese, K; Verhaegen, J

2013-01-01

We describe five cases of Actinomyces neuii, isolated from different clinical specimens over a period of five months (from June to October 2011), followed by a review of literature on infections with this micro-organism. All Actinomyces neuii strains were cultured or subcultured on horse blood agar. Identification took place using matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS). Identification was confirmed by conventional biochemical tests and API Coryne test strips (BioMérieux SA). Susceptibility testing was performed on Mueller-Hinton agar supplemented with horse blood, using E-tests (BioMérieux SA). The minimal inhibitory concentrations were determined after 24 and 48 hours of incubation in a 5% CO2 environment. Isolation of this micro-organism was associated with abscesses in two patients and chronic osteomyelitis in one patient. The remaining two patients had positive blood cultures which grew Actinomyces neuii, either as contamination or as catheter-related infection. All Actinomyces neuii identifications were obtained by MALDI-TOF MS and were confirmed by conventional biochemical and API Coryne tests. Identification of one isolate was also confirmed by 16S rRNA sequencing. All strains were susceptible to penicillin. One strain showed heteroresistance for macrolides and lincosamides. Minimal inhibitory concentrations were more reliable and easier to read after 48 hours of incubation, as compared to 24 hours. MALDI-TOF MS analysis allows rapid and reliable identification of Actinomyces neuii, even at subspecies level.

Monitoring of clinical strains and environmental fungal aerocontamination to prevent invasive aspergillosis infections in hospital during large deconstruction work: a protocol study

PubMed Central

Loeffert, Sophie Tiphaine; Melloul, Elise; Dananché, Cédric; Hénaff, Laetitia; Bénet, Thomas; Cassier, Pierre; Dupont, Damien; Guillot, Jacques; Botterel, Françoise; Wallon, Martine; Gustin, Marie-Paule; Vanhems, Philippe

2017-01-01

Introduction Monitoring fungal aerocontamination is an essential measure to prevent severe invasive aspergillosis (IA) infections in hospitals. One central block among 32 blocks of Edouard Herriot Hospital (EHH) was entirely demolished in 2015, while care activities continued in surrounding blocks. The main objective was to undertake broad environmental monitoring and clinical surveillance of IA cases to document fungal dispersion during major deconstruction work and to assess clinical risk. Methods and analysis A daily environmental survey of fungal loads was conducted in eight wards located near the demolition site. Air was collected inside and outside selected wards by agar impact samplers. Daily spore concentrations were monitored continuously by volumetric samplers at a flow rate of 10 L.min-1. Daily temperature, wind direction and speed as well as relative humidity were recorded by the French meteorological station Meteociel. Aspergillus fumigatus strains stored will be genotyped by multiple-locus, variable-number, tandem-repeat analysis. Antifungal susceptibility will be assessed by E-test strips on Roswell Park Memorial Institute medium supplemented with agar. Ascertaining the adequacy of current environmental monitoring techniques in hospital is of growing importance, considering the rising impact of fungal infections and of curative antifungal costs. The present study could improve the daily management of IA risk during major deconstruction work and generate new data to ameliorate and redefine current guidelines. Ethics and dissemination This study was approved by the clinical research and ethics committees of EHH. PMID:29175886

The effects of melatonin on colonization of neonate spermatogonial mouse stem cells in a three-dimensional soft agar culture system.

PubMed

Navid, Shadan; Abbasi, Mehdi; Hoshino, Yumi

2017-10-17

Melatonin is a pleiotropic hormone with powerful antioxidant activity both in vivo and in vitro. The present study aimed to investigate the effects of melatonin on the proliferation efficiency of neonatal mouse spermatogonial stem cells (SSCs) using a three-dimensional soft agar culture system (SACS) which has the capacity to induce development of SSCs similar to in vivo conditions. SSCs were isolated from testes of neonate mice and their purities were assessed by flow cytometry using PLZF antibody. Isolated testicular cells were cultured in the upper layer of the SACS in αMEM medium in the absence or presence of melatonin extract for 4 weeks. The identity of colonies was confirmed by alkaline phosphatase staining and immunocytochemistry using PLZF and α6 integrin antibodies. The number and diameter of colonies of SSCs in the upper layer were evaluated at days 14 and 28 of culture. The number and diameter of colonies of SSCs were significantly higher in the melatonin group compared with the control group. The levels of expression of ID-4 and Plzf, unlike c-kit, were significantly higher in the melatonin group than in the control group. Results of the present study show that supplementation of the culture medium (SACS) with 100 μM melatonin significantly decreased reactive oxygen species (ROS) production in the treated group compared with the control group, and increased SSC proliferation.

Effect of minerals on accumulation of Cs by fungus Saccaromyces cerevisiae.

PubMed

Ohnuki, Toshihiko; Sakamoto, Fuminori; Yamasaki, Shinya; Kozai, Naofumi; Shiotsu, Hiroyuki; Utsunomiya, Satoshi; Watanabe, Naoko; Kozaki, Tamotsu

2015-06-01

The accumulation of Cs by unicellular fungus of Saccharomyces cerevisiae in the presence of minerals has been studied to elucidate the role of microorganisms in the migration of radioactive Cs in the environment. Two different types of experiments were employed: experiments using stable Cs to examine the effect of a carbon source on the accumulation of Cs, and accumulation experiments of radioactive Cs from agar medium containing (137)Cs and zeolite, vermiculite, phlogopite, smectite, mica, or illite as mineral supplements. In the former type of experiments, the Cs-accumulated cells were analyzed by scanning electron microscopy equipped with energy dispersive X-ray analysis (SEM-EDS). In the latter type, the radioactivity in the yeast cells was measured by an autoradiography technique. When a carbon source was present, higher amounts of Cs accumulated in the cells than in the resting condition without a carbon source. Analyses with SEM-EDS showed that no mineral formed on the cell surface. These results indicate that the yeast cells accumulate Cs by adsorption on the cell surface and intracellular accumulation. In the presence of minerals in the agar medium, the radioactivity in the yeast cells was in the order of mica > smectite, illite > vermiculite, phlogopite, zeolite. This order is inversely correlated to the ratio of the concentration of radioactive Cs between the minerals and the medium solution. These results strongly suggest that the yeast accumulates radioactive Cs competitively with minerals. Copyright © 2015 Elsevier Ltd. All rights reserved.

Extracellular deoxyribonuclease production by periodontal bacteria.

PubMed

Palmer, L J; Chapple, I L C; Wright, H J; Roberts, A; Cooper, P R

2012-08-01

Whilst certain bacteria have long been known to secrete extracellular deoxyribonuclease (DNase), the purpose in microbial physiology was unclear. Recently, however, this enzyme has been demonstrated to confer enhanced virulence, enabling bacteria to evade the host's immune defence of extruded DNA/chromatin filaments, termed neutrophil extracellular traps (NETs). As NETs have recently been identified in infected periodontal tissue, the aim of this study was to screen periodontal bacteria for extracellular DNase activity. To determine whether DNase activity was membrane bound or secreted, 34 periodontal bacteria were cultured in broth and on agar plates. Pelleted bacteria and supernatants from broth cultures were analysed for their ability to degrade DNA, with relative activity levels determined using an agarose gel electrophoresis assay. Following culture on DNA-supplemented agar, expression was determined by the presence of a zone of hydrolysis and DNase activity related to colony size. Twenty-seven bacteria, including red and orange complex members Porphyromonas gingivalis, Tannerella forsythia, Fusobacterium nucleatum, Parvimonas micra, Prevotella intermedia, Streptococcus constellatus, Campylobacter rectus and Prevotella nigrescens, were observed to express extracellular DNase activity. Differences in DNase activity were noted, however, when bacteria were assayed in different culture states. Analysis of the activity of secreted DNase from bacterial broth cultures confirmed their ability to degrade NETs. The present study demonstrates, for the first time, that DNase activity is a relatively common property of bacteria associated with advanced periodontal disease. Further work is required to determine the importance of this bacterial DNase activity in the pathogenesis of periodontitis. © 2011 John Wiley & Sons A/S.

Effects of solid-medium type on routine identification of bacterial isolates by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry.

PubMed

Anderson, Neil W; Buchan, Blake W; Riebe, Katherine M; Parsons, Lauren N; Gnacinski, Stacy; Ledeboer, Nathan A

2012-03-01

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a rapid method for the identification of bacteria. Factors that may alter protein profiles, including growth conditions and presence of exogenous substances, could hinder identification. Bacterial isolates identified by conventional methods were grown on various media and identified using the MALDI Biotyper (Bruker Daltonics, Billerica, MA) using a direct smear method and an acid extraction method. Specimens included 23 Pseudomonas isolates grown on blood agar, Pseudocel (CET), and MacConkey agar (MAC); 20 Staphylococcus isolates grown on blood agar, colistin-nalidixic acid agar (CNA), and mannitol salt agar (MSA); and 25 enteric isolates grown on blood agar, xylose lysine deoxycholate agar (XLD), Hektoen enteric agar (HE), salmonella-shigella agar (SS), and MAC. For Pseudomonas spp., the identification rate to genus using the direct method was 83% from blood, 78% from MAC, and 94% from CET. For Staphylococcus isolates, the identification rate to genus using the direct method was 95% from blood, 75% from CNA, and 95% from MSA. For enteric isolates, the identification rate to genus using the direct method was 100% from blood, 100% from MAC, 100% from XLD, 92% from HE, and 87% from SS. Extraction enhanced identification rates. The direct method of MALDI-TOF analysis of bacteria from selective and differential media yields identifications of varied confidence. Notably, Staphylococci spp. from CNA exhibit low identification rates. Extraction enhances identification rates and is recommended for colonies from this medium.

Trace Amounts of Furan-2-Carboxylic Acids Determine the Quality of Solid Agar Plates for Bacterial Culture

PubMed Central

Hara, Shintaro; Isoda, Reika; Tahvanainen, Teemu; Hashidoko, Yasuyuki

2012-01-01

Background Many investigators have recognised that a significant proportion of environmental bacteria exist in a viable but non-culturable state on agar plates, and some researchers have also noticed that some of such bacteria clearly recover their growth on matrices other than agar. However, the reason why agar is unsuitable for the growth of some bacteria has not been addressed. Methodology/Principal Findings According to the guide of a bioassay for swarming inhibition, we identified 5-hydroxymethylfuran-2-carboxylic acid (5-HMFA) and furan-2-carboxylic acid (FA) as factors that inhibit bacterial swarming and likely inhibit extracellular polysaccharide production on agar. The furan-2-carboxylic acids 5-HMFA and FA effectively inhibited the swarming and swimming of several environmental bacteria at concentrations of 1.8 and 2.3 µg L−1 (13 and 21 nmol L−1), respectively, which are equivalent to the concentrations of these compounds in 0.3% agar. On Luria-Bertani (LB) plates containing 1.0% agar that had been previously washed with MeOH, a mixture of 5-HMFA and FA in amounts equivalent to their original concentrations in the unwashed agar repressed the swarming of Escherichia coli K12 strain W3110, a representative swarming bacterium. Conclusions/Significance Agar that contains trace amounts of 5-HMFA and FA inhibits the proliferation of some slow-growing or difficult-to-culture bacteria on the plates, but it is useful for single colony isolation due to the ease of identification of swarmable bacteria as the non-swarmed colonies. PMID:22848437

Comparative analysis of cryopreservation methods in Chlamydomonas reinhardtii.

PubMed

Scarbrough, Chasity; Wirschell, Maureen

2016-10-01

Chlamydomonas is a model organism used for studies of many important biological processes. Traditionally, strains have been propagated on solid agar, which requires routine passaging for long-term maintenance. Cryopreservation of Chlamydomonas is possible, yet long-term viability is highly variable. Thus, improved cryopreservation methods for Chlamydomonas are an important requirement for sustained study of genetically defined strains. Here, we tested a commercial cryopreservation kit and directly compared it's effectiveness to a methanol-based method. We also tested thaw-back procedures comparing the growth of cells in liquid culture or on solid agar media. We demonstrated that methanol was the superior cryopreservation method for Chlamydomonas compared to the commercial kit and that post-thaw culture conditions dramatically affect viability. We also demonstrated that cryopreserved cells could be successfully thawed and plated directly onto solid agar plates. Our findings have important implications for the long-term storage of Chlamydomonas that can likely be extended to other algal species. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Immobilization of pectin depolymerising polygalacturonase using different polymers.

PubMed

Ur Rehman, Haneef; Aman, Afsheen; Nawaz, Muhammad Asif; Karim, Asad; Ghani, Maria; Baloch, Abdul Hameed; Ul Qader, Shah Ali

2016-01-01

Polygalacturonase catalyses the hydrolysis of pectin substances and widely has been used in food and textile industries. In current study, different polymers such as calcium alginate beads, polyacrylamide gel and agar-agar matrix were screened for the immobilization of polygalacturonase through entrapment technique. Polyacrylamide gel was found to be most promising one and gave maximum (89%) immobilization yield as compared to agar-agar (80%) and calcium alginate beads (46%). The polymers increased the reaction time of polygalacturonase and polymers entrapped polygalacturonases showed maximum pectinolytic activity after 10 min of reaction as compared to free polygalacturonase which performed maximum activity after 5.0 min of reaction time. The temperature of polygalacturonase for maximum enzymatic activity was increased from 45°C to 50°C and 55°C when it was immobilized within agar-agar and calcium alginate beads, respectively. The optimum pH (pH 10) of polygalacturonase was remained same when it was immobilized within polyacrylamide gel and calcium alginate beads, but changed from pH 10 to pH 9.0 after entrapment within agar-agar. Thermal stability of polygalacturonase was improved after immobilization and immobilized polygalacturonases showed higher tolerance against different temperatures as compared to free enzyme. Polymers entrapped polygalacturonases showed good reusability and retained more than 80% of their initial activity during 2nd cycles. Copyright © 2015 Elsevier B.V. All rights reserved.

Experimental strategy to discover microbes with gluten-degrading enzyme activities

NASA Astrophysics Data System (ADS)

Helmerhorst, Eva J.; Wei, Guoxian

2014-06-01

Gluten proteins contained in the cereals barley, rye and wheat cause an inflammatory disorder called celiac disease in genetically predisposed individuals. Certain immunogenic gluten domains are resistant to degradation by mammalian digestive enzymes. Enzymes with the ability to target such domains are potentially of clinical use. Of particular interest are gluten-degrading enzymes that would be naturally present in the human body, e.g. associated with resident microbial species. This manuscript describes a selective gluten agar approach and four enzyme activity assays, including a gliadin zymogram assay, designed for the selection and discovery of novel gluten-degrading microorganisms from human biological samples. Resident and harmless bacteria and/or their derived enzymes could potentially find novel applications in the treatment of celiac disease, in the form of a probiotic agent or as a dietary enzyme supplement.

Experimental Strategy to Discover Microbes with Gluten-degrading Enzyme Activities.

PubMed

Helmerhorst, Eva J; Wei, Guoxian

2014-05-05

Gluten proteins contained in the cereals barley, rye and wheat cause an inflammatory disorder called celiac disease in genetically predisposed individuals. Certain immunogenic gluten domains are resistant to degradation by mammalian digestive enzymes. Enzymes with the ability to target such domains are potentially of clinical use. Of particular interest are gluten-degrading enzymes that would be naturally present in the human body, e.g. associated with resident microbial species. This manuscript describes a selective gluten agar approach and four enzyme activity assays, including a gliadin zymogram assay, designed for the selection and discovery of novel gluten-degrading microorganisms from human biological samples. Resident and harmless bacteria and/or their derived enzymes could potentially find novel applications in the treatment of celiac disease, in the form of a probiotic agent or as a dietary enzyme supplement.

Genetic transformation of Begonia tuberhybrida by Ri rol genes.

PubMed

Kiyokawa, S; Kikuchi, Y; Kamada, H; Harada, H

1996-04-01

We have developed an Agrobacterium -mediated transformation system for commercial Begonia species. The leaf explants of Begonia semperflorens, Begonia x hiemalis and B. tuberhybrida were inoculated with Agrobacterium tumefaciens LBA4404 harboring a binary vector pBI121 which contains rolA, B and C genes of an agropine type Ri plasmid (pRiA4b). Kanamycin resistant shoots of B. tuberhybrida were obtained on MS agar medium supplemented with 0.1 mg/l NAA, 0.5 mg/l BA, 500 mg/l claforan and 100 mg/l kanamycin. These shoots exhibited GUS activity and Southern analysis showed a single copy insertion into the genome. When the transgenic plants were transferred to soil, they displayed the phenotype specific to the transgenic plants by A. rhizogenes such as dwarfness, delay of flowering, and wrinkled leaves and petals.

Production of secondary metabolites by some terverticillate penicillia on carbohydrate-rich and meat substrates.

PubMed

Núñez, Félix; Westphal, Carmen D; Bermúdez, Elena; Asensio, Miguel A

2007-12-01

Most terverticillate penicillia isolated from dry-cured meat products are toxigenic, but their ability to produce hazardous metabolites on meat-based substrates is not well known. The production of extrolites by selected terverticillate penicillia isolated from dry-cured ham has been studied on carbohydrate-rich media (malt extract agar, Czapek yeast autolysate agar, rice extract agar, and rice), meat extract triolein salt agar, and ham slices. Chloroform extracts from the selected strains grown on malt extract agar were toxic for the brine shrimp (Artemia salina) larvae and VERO cells at a concentration of 2 mg/ml, but 0.02 mg/ml produced no toxic effect. Analysis by high-pressure liquid chromatography (HPLC) coupled with photodiode array detection (DAD) or with mass spectrometry (MS) and an atmospheric pressure chemical ionization (APCI) source revealed different biologically active metabolites: cyclopiazonic acid and rugulovasine A from Penicillium commune; verrucosidin, anacine, puberuline, verrucofortine, and viridicatols from Penicillium polonicum; arisugacin and viridicatols from Penicillium echinulatum; and compactin and viridicatols from Penicillium solitum. Most of these metabolites, including the amino acid-derived compounds, were produced in the media containing high levels of carbohydrates. High concentrations of nitrogen compounds in the medium does not imply a greater production of the metabolites studied, not even those derived from the amino acids. However, molds growing on dry-cured ham are able to synthesize limited amounts of some secondary metabolites, a fact not previously reported. The combination of HPLC coupled with DAD and MS-APCI was useful for identification of closely related terverticillate Penicillium species from dry-cured ham. These techniques could be used to characterize the risk associated with the potential production of secondary metabolites in cured meats.

Incubation at room temperature may be an independent factor that induces chlamydospore production in Candida dubliniensis.

PubMed

Sancak, Banu; Colakoglu, Sule; Acikgoz, Ziya Cibali; Arikan, Sevtap

2005-08-01

Production of chlamydospores is one of the phenotypic features used to differentiate Candida albicans and Candida dubliniensis. C. albicans produces few chlamydospores on only cornmeal/rice-Tween agar at room temperature, whereas C. dubliniensis produces abundant chlamydospores at this temperature both on cornmeal agar and some other commonly used media. We tried to determine whether the room temperature is the main factor that induces chlamydospore production of C. dubliniensis, regardless of the medium used. For this purpose, 100 C. albicans and 24 C. dubliniensis isolates were tested for chlamydospore production at room temperature and at 37 degrees C on some routinely used media, including eosin-methylene blue agar (EMB), nutrient agar (NA), nutrient broth (NB), and also on an investigational medium, phenol red agar (PR). At 37 degrees C, none of the isolates produced chlamydospores on any of the tested media. At 26 degrees C, all C. dubliniensis isolates produced abundant chlamydospores and pseudohyphae after 24-48 h on all tested media. At this incubation temperature, all C. albicans isolates failed to produce chlamydospores and pseudohyphae on EMB, NA, and NB, whereas 2 of the C. albicans isolates produced a few chlamydospores on PR. We also observed that all C. dubliniensis isolates tested on EMB and PR produced rough colonies with a hyphal fringe around the colonies, whereas none of the C. albicans isolates showed this property. In conclusion, incubation at 26 degrees C may play the key role for production of abundant chlamydospores and pseudohyphae by C. dubliniensis. Comprehensive molecular studies are needed to clarify the genetic basis of this observation. Using EMB and PR may be an inexpensive, a time-saving, and a simple way of presumptive identification of C. dubliniensis based on chlamydospore formation and colony morphology.

Evaluation of anti-inflammatory and antimicrobial activity of AHPL/AYTOP/0213 cream

PubMed Central

Nipanikar, Sanjay U.; Nagore, Dheeraj; Chitlange, Soham S.; Buzruk, Devashree

2017-01-01

Background: Acne vulgaris is almost a widespread disease occurring in all races. Propionibacterium acnes initiate acne and inflammatory mediators aggravate it. Conventional therapies for acne include comedolytic, anti-inflammatory, and anti-biotic agents. Due to adverse effects of these therapies, people are searching for alternative options. In this context, a polyherbal formulation AHPL/AYTOP/0213 cream was developed for the treatment of Acne. Objective: The objective of this study is to study anti-inflammatory and antimicrobial activities of AHPL/AYTOP/0213 cream. Materials and Methods: Skin irritation study was conducted on AHPL/AYTOP/0213 cream as per OECD guidelines. (1) Anti-inflammatory activity: Anti-inflammatory activity of AHPL/AYTOP/0213 cream in comparison with diclofenac sodium cream was assessed in carrageenan-induced rat paw edema model. (2) Antimicrobial activity for P. acnes: P. acnes were incubated under anaerobic conditions. Aliquots of molten brain–heart infusion with glucose agar were used as the agar base. Formulation and clindamycin (10 mg/ml) were introduced in to the Agar wells randomly. (3) Antimicrobial activity for Staphylococcus epidermidis and Staphylococcus aureus: bacteria were incubated under aerobic conditions at 37°C. Tryptic soy broth with glucose agar was used as the agar base. A volume of 0.5 ml of formulation and clindamycin (10 mg/ml) were introduced in to the wells randomly. The antibacterial activity was evaluated by measuring zones of inhibition (in mm). Results: AHPL/AYTOP/0213 cream is nonirritant. Significant reduction in rat paw edema (43%) was observed with AHPL/AYTOP/0213 which was also comparable to diclofenac sodium cream (56.09%). Zone of inhibition for formulation was 20.68 mm, 28.20 mm, and 21.40 mm for P. acnes, S. epidermidis and S. aureus, respectively, which was comparable to clindamycin. The minimum inhibitory concentration of formulation AHPL/AYTOP/0213 obtained in anti-microbial study was 2.5 mg/mL. Conclusion: AHPL/AYTOP/0213 cream is nonirritant and possesses significant anti-inflammatory and antimicrobial activities, which further justifies its role in the management of acne vulgaris. PMID:29861599

Thermal characterization of magnetically aligned carbonyl iron/agar composites.

PubMed

Diaz-Bleis, D; Vales-Pinzón, C; Freile-Pelegrín, Y; Alvarado-Gil, J J

2014-01-01

Composites of magnetic particles into polymeric matrices have received increasing research interest due to their capacity to respond to external magnetic or electromagnetic fields. In this study, agar from Gelidium robustum has been chosen as natural biocompatible polymer to build the matrix of the magnetic carbonyl iron particles (CIP) for their uses in biomedical fields. Heat transfer behavior of the CIP-agar composites containing different concentrations (5, 10, 15, 20, 25 and 30% w/w) of magnetically aligned and non-aligned CIP in the agar matrix was studied using photothermal radiometry (PTR) in the back-propagation emission configuration. The morphology of the CIP-agar composites with aligned and non-aligned CIP under magnetic field was also evaluated by scanning electron microscopy (SEM). The results revealed a dominant effect of CIP concentration over the alignment patterns induced by the magnetic field, which agrees with the behavior of the thermal diffusivity and thermal conductivity. Agar served as a perfect matrix to be used with CIP, and CIP-agar composites magnetically aligned at 20% CIP concentration can be considered as promising 'smart' material for hyperthermia treatments in the biomedical field. Copyright © 2013 Elsevier Ltd. All rights reserved.

Recovery of Oesophagostomum dentatum from pigs by isolation of parasites migrating from large intestinal contents embedded in agar-gel.

PubMed

Slotved, H C; Barnes, E H; Bjørn, H; Christensen, C M; Eriksen, L; Roepstorff, A; Nansen, P

1996-06-01

Four groups with three pigs in each group were inoculated with Oesophagostomum dentatum larvae (L3 larvae). Groups 1 and 3 were inoculated with 20,000 larvae, and Groups 2 and 4 with 200,000 larvae. On Days 11 and 34, respectively, Groups 1 and 2 and Groups 3 and 4 were slaughtered, and the contents from the large intestines collected. Subsamples of intestinal contents were mixed with agar to a final concentration of 1% agar and allowed to set. The worms were allowed to migrate from the agar-gel into 38 degrees C 0.9% saline overnight. Then the worms were collected on a sieve (38 microns mesh) and counted. The worms retained in the agar-gel were counted after pouring the melted agar through a sieve (38 microns mesh). The results showed that more than 95% of the worms migrated out of the agar-gel, and subsequently were available for counting in an almost clean suspension. Additionally the method yielded a high worm recovery; all stages were recovered. The recovery percentage was not significantly affected by either the dose of parasites or the time interval from slaughtering to start of incubation (37-128 min).

Quantitative SIMS Imaging of Agar-Based Microbial Communities.

PubMed

Dunham, Sage J B; Ellis, Joseph F; Baig, Nameera F; Morales-Soto, Nydia; Cao, Tianyuan; Shrout, Joshua D; Bohn, Paul W; Sweedler, Jonathan V

2018-05-01

After several decades of widespread use for mapping elemental ions and small molecular fragments in surface science, secondary ion mass spectrometry (SIMS) has emerged as a powerful analytical tool for molecular imaging in biology. Biomolecular SIMS imaging has primarily been used as a qualitative technique; although the distribution of a single analyte can be accurately determined, it is difficult to map the absolute quantity of a compound or even to compare the relative abundance of one molecular species to that of another. We describe a method for quantitative SIMS imaging of small molecules in agar-based microbial communities. The microbes are cultivated on a thin film of agar, dried under nitrogen, and imaged directly with SIMS. By use of optical microscopy, we show that the area of the agar is reduced by 26 ± 2% (standard deviation) during dehydration, but the overall biofilm morphology and analyte distribution are largely retained. We detail a quantitative imaging methodology, in which the ion intensity of each analyte is (1) normalized to an external quadratic regression curve, (2) corrected for isomeric interference, and (3) filtered for sample-specific noise and lower and upper limits of quantitation. The end result is a two-dimensional surface density image for each analyte. The sample preparation and quantitation methods are validated by quantitatively imaging four alkyl-quinolone and alkyl-quinoline N-oxide signaling molecules (including Pseudomonas quinolone signal) in Pseudomonas aeruginosa colony biofilms. We show that the relative surface densities of the target biomolecules are substantially different from values inferred through direct intensity comparison and that the developed methodologies can be used to quantitatively compare as many ions as there are available standards.

Demonstrating Effectiveness of Antibiotics Against Known Bacteria Strains

ERIC Educational Resources Information Center

Keefe, Lois M.

1977-01-01

Procedures are described for showing the effectiveness of antibiotics (penicillin, ampicillin, and tetracycline) against a nonpathogenic bacteria strain (Bacillus cereus). Methods are outlined for preparing nutrient agar, sterilizing tubes, pouring agar plates, preparing antibiotic discs, and transferring antibiotic discs to agar plates. (CS)

Comparison of performance of the novel chromogenic spectra VRE agar to that of bile esculin azide and Campylobacter agars for detection of vancomycin-resistant enterococci in fecal samples.

PubMed

Jenkins, S G; Raskoshina, L; Schuetz, A N

2011-11-01

A total of 142 stool specimens were evaluated for vancomycin-resistant enterococcus (VRE). Twenty-four-hour sensitivities and specificities, respectively, were 98% and 95% for Spectra VRE chromogenic agar (Remel, Lenexa, KS), 86% and 92% for bile esculin azide with vancomycin (BEAV; Remel), and 96.5% and 92% for Campylobacter agar (CAMPY; Remel). Spectra VRE and CAMPY are significantly more sensitive at 24 h than BEAV.

Gelling agents and culture vessels affect in vitro multiplication of banana plantlets.

PubMed

Kaçar, Y A; Biçen, B; Varol, I; Mendi, Y Y; Serçe, S; Cetiner, S

2010-03-09

Agar is the most commonly used gelling agent in media for plant tissue culture. Because of the high price of tissue-culture-grade agar, attempts have been made to identify suitable alternatives. The type of culture vessel and lid also affects the gaseous composition inside the vessel as well as light penetration. In turn, the vessel affects growth parameters, such as shoot elongation, proliferation and fresh weight, as well as hyperhydric degradation processes. We examined the effects of different culture vessels, including commercial glass jars, magenta boxes, and disposable containers, as well as different gelling agents (agar-agar, Agargel, Phytagel, and plant agar) on the micropropagation of Dwarf Cavendish bananas in an effort to find a combination that yields large numbers of high-quality seedlings. The different culture vessels did not significantly affect seedling culture success. The medium significantly affected shoot weight. Phytagel resulted in the highest shoot weight (overall mean = 2.4 g), while agar, Agargel and plant agar resulted in 1.7, 2.2 and 2.2 g, respectively. Disposable container/Phytagel and Magenta/Agargel combinations yielded the highest shoot weights (2.9 and 3.0 g, respectively). Mean shoot length increased progressively with subculture (four subcultures were made). The highest mean shoot length was obtained with Phytagel and Agargel media (6.4 and 6.3 cm, respectively). Shoot number was significantly affected by medium only at subculture 4. Overall, the highest mean shoot length was obtained with the Magenta/Agargel combination (8.5 cm). Phytagel and plant agar gave higher mean shoot number than agar and Agargel (2.1, 2.1 and 1.7 and 1.9, respectively). The costs of the media and of the culture vessels need to be taken into account for final choice of the banana shoot culture system.

Physical-mechanical properties of agar/κ-carrageenan blend film and derived clay nanocomposite film.

PubMed

Rhim, Jong-Whan

2012-12-01

Binary blend films with different mixing ratio of agar and κ-carrageenan were prepared using a solution casting method with and without nanoclay and the effect of their composition on the mechanical, water vapor barrier, and water resistance properties was tested. The tensile strength (TS) of the κ-carrageenan film was greater than that of agar film. The water vapor permeability (WVP) of the agar film was lower than that of κ-carrageenan film, the swelling ratio (SR) and water solubility (WS) of κ-carrageenan film were higher than those of agar film. Each property of the binary blend films varied proportionately depending on the mixing ratio of each component. The XRD result indicated that the nanocomposite with agar/κ-carrageenan/clay (Cloisite(®) Na(+)) was intercalated. Consequently, the mechanical strength, water vapor barrier properties, and water contact angle (CA) were significantly (P < 0.05) improved through nanocomposite formation. © 2012 Institute of Food Technologists®

Comparative studies on the conformational change and aggregation behavior of irradiated carrageenans and agar by dynamic light scattering.

PubMed

Abad, Lucille; Okabe, Satoshi; Shibayama, Mitsuhiro; Kudo, Hisaaki; Saiki, Seiichi; Aranilla, Charito; Relleve, Lorna; de la Rosa, Alumanda

2008-01-01

The conformational associative properties of kappa-, iota-, and lambda-carrageenan and agar with irradiation dose were studied by dynamic light scattering. The random scission of the carrageenans and agar by gamma irradiation resulted in the formation of polydispersed lower molecular weight fragments. At high doses, the system moves towards uniformity. Conformational change from coil to helix was observed in all carrageenans and agar at doses up to 100 kGy. The conformational change in lambda-carrageenan may be due to the irregular and hybrid structure of this polysaccharide. Only agar and lambda-carrageenan still undergo conformational transition at a high dose of 200 kGy. Gelation is observed for kappa-, iota-carrageenan up to a dose of 50 kGy while gelation is still observed at 100 kGy for agar. Increase in the hydrodynamic radius with decreasing temperatures for the non-irradiated carrageenans follows this order: lambda-carrageenan>kappa-carrageenan>iota-carrageenan. Slight increases in hydrodynamic radius were observed with irradiation.

Initial cytotoxicity assays of media for sulfate-reducing bacteria: An endodontic biopharmaceutical product under development.

PubMed

Heggendorn, Fabiano Luiz; Silva, Gabriela Cristina de Carvalho; Cardoso, Elisama Azevedo; Castro, Helena Carla; Gonçalves, Lúcio Souza; Dias, Eliane Pedra; Lione, Viviane de Oliveira Freitas; Lutterbach, Márcia Teresa Soares

2016-01-01

This study assessed the cell viability of the inoculation vehicle of BACCOR (a combination of sulfate-reducing bacteria plus a culture media for bacteria), a biopharmaceutical product under development for dental use as aid in fractured endodontic file removal from the root canal. Different culture media for bacteria were evaluated: modified Postgate E (MCP-E mod), Modified Postgate E without Agar-agar (MCP-E w/Ag), Postgate C with Agar-agar (MCP-C Ag) and Postgate C without Agar-agar (MCP-C w/Ag). Cytotoxicity was quantified by the MTT test, exposing L929 and Vero cell lines to the vehicles over 24 h. The exposure of L929 cell line to MCP-E w/Ag resulted in biocompatibility (52% cell viability), while the exposure of the Vero kidney line revealed only MCP-E mod as cytotoxic. When diluted, all the vehicles showed biocompatibility with both cell lines. MCP-E w/Ag was the vehicle chosen for BACCOR, because of its biocompatibility with the cells used.

Rheological and structural characterization of agar/whey proteins insoluble complexes.

PubMed

Rocha, Cristina M R; Souza, Hiléia K S; Magalhães, Natália F; Andrade, Cristina T; Gonçalves, Maria Pilar

2014-09-22

Complex coacervation between whey proteins and carboxylated or highly sulphated polysaccharides has been widely studied. The aim of this work was to characterise a slightly sulphated polysaccharide (agar) and whey protein insoluble complexes in terms of yield, composition and physicochemical properties as well as to study their rheological behaviour for better understanding their structure. Unlike other sulphated polysaccharides, complexation of agar and whey protein at pH 3 in the absence of a buffering agent resulted in a coacervate that was a gel at 20°C with rheological properties and structure similar to those of simple agar gels, reinforced by proteins electrostatically aggregated to the agar network. The behaviour towards heat treatment was similar to that of agar alone, with a high thermal hysteresis and almost full reversibility. In the presence of citrate buffer, the result was a "flocculated solid", with low water content (75-81%), whose properties were governed by protein behaviour. Copyright © 2014 Elsevier Ltd. All rights reserved.

Agar Sediment Test for Assessing the Suitability of Organic Waste Streams for Recovering Nutrients by the Aquatic Worm Lumbriculus variegatus.

PubMed

Laarhoven, Bob; Elissen, H J H; Temmink, H; Buisman, C J N

2016-01-01

An agar sediment test was developed to evaluate the suitability of organic waste streams from the food industry for recovering nutrients by the aquatic worm Lumbriculus variegatus (Lv). The effects of agar gel, sand, and food quantities in the sediment test on worm growth, reproduction, and water quality were studied. Agar gel addition ameliorated growth conditions by reducing food hydrolysis and altering sediment structure. Best results for combined reproduction and growth were obtained with 0.6% agar-gel (20 ml), 10 g. fine sand, 40 g. coarse sand, and 105 mg fish food (Tetramin). With agar gel, ingestion and growth is more the result of addition of food in its original quality. Final tests with secondary potato starch sludge and wheat bran demonstrated that this test is appropriate for the comparison of solid feedstuffs and suspended organic waste streams. This test method is expected to be suitable for organic waste studies using other sediment dwelling invertebrates.

Strategies to improve the mechanical strength and water resistance of agar films for food packaging applications.

PubMed

Sousa, Ana M M; Gonçalves, Maria P

2015-11-05

Agar films possess several properties adequate for food packaging applications. However, their high cost-production and quality variations caused by physiological and environmental factors affecting wild seaweeds make them less attractive for industries. In this work, native (NA) and alkali-modified (AA) agars obtained from sustainably grown seaweeds (integrated multi-trophic aquaculture) were mixed with locust bean gum (LBG) to make 'knife-coated' films with fixed final concentration (1 wt%) and variable agar/LBG ratios. Agar films were easier to process upon LBG addition (viscosity increase and gelling character decrease of the film-forming solutions observed by dynamic oscillatory and steady shear measurements). The mechanical properties and water resistance were optimal for films with 50 and/or 75% LBG contents and best in the case of NA (cheaper to extract). These findings can help reduce the cost-production of agar packaging films. Moreover, the controlled cultivation of seaweeds can provide continuous and reliable feedstock for transformation industries. Copyright © 2015 Elsevier Ltd. All rights reserved.

Agar Sediment Test for Assessing the Suitability of Organic Waste Streams for Recovering Nutrients by the Aquatic Worm Lumbriculus variegatus

PubMed Central

Laarhoven, Bob; Elissen, H. J. H.; Temmink, H.; Buisman, C. J. N.

2016-01-01

An agar sediment test was developed to evaluate the suitability of organic waste streams from the food industry for recovering nutrients by the aquatic worm Lumbriculus variegatus (Lv). The effects of agar gel, sand, and food quantities in the sediment test on worm growth, reproduction, and water quality were studied. Agar gel addition ameliorated growth conditions by reducing food hydrolysis and altering sediment structure. Best results for combined reproduction and growth were obtained with 0.6% agar-gel (20 ml), 10 g. fine sand, 40 g. coarse sand, and 105 mg fish food (Tetramin). With agar gel, ingestion and growth is more the result of addition of food in its original quality. Final tests with secondary potato starch sludge and wheat bran demonstrated that this test is appropriate for the comparison of solid feedstuffs and suspended organic waste streams. This test method is expected to be suitable for organic waste studies using other sediment dwelling invertebrates. PMID:26937632

An Agar-Based Method for Plating Marine Protozoan Parasites of the Genus Perkinsus.

PubMed

Cold, Emma R; Freyria, Nastasia J; Martínez Martínez, Joaquín; Fernández Robledo, José A

2016-01-01

The genus Perkinsus includes protozoan parasites of mollusks responsible for losses in the aquaculture industry and hampering the recovery of natural shellfish beds worldwide, and they are a key taxon for understanding intracellular parasitism adaptations. The ability to propagate the parasite in liquid media, in the absence of the host, has been crucial for improving understanding of its biology; however, alternative techniques to grow the parasite are needed to explore other basic aspects of the Perkinsus spp. biology. We optimized a DME: Ham's F12-5% FBS- containing solid agar medium for plating Perkinsus marinus. This solid medium supported trophozoite propagation both by binary fission and schizogony. Colonies were visible to the naked eye 17 days after plating. We tested the suitability of this method for several applications, including the following: 1) Subcloning P. marinus isolates: single discrete P. marinus colonies were obtained from DME: Ham's F12-5% FBS- 0.75% agar plates, which could be further propagated in liquid medium; 2) Subcloning engineered Perkinsus mediterraneus MOE[MOE]: GFP by streaking cultures on plates; 3) Chemical susceptibility: Infusing the DME: Ham's F12-5% FBS- 0.75% agar plates with triclosan resulted in inhibition of the parasite propagation in a dose-dependent manner. Altogether, our plating method has the potential for becoming a key tool for investigating diverse aspects of Perkinsus spp. biology, developing new molecular tools, and for biotechnological applications.

The thin-layer agar method for direct phenotypic detection of multi- and extensively drug-resistant tuberculosis.

PubMed

Ardizzoni, E; Mulders, W; Kotrikadze, T; Aspindzelashvili, R; Goginashvili, L; Pangtey, H; Varaine, F; Bastard, M; Rigouts, L; de Jong, B C

2015-12-01

Molecular techniques rapidly detect resistance to rifampicin (RMP) and isoniazid (INH), but do not eliminate the need for culture-based drug susceptibility testing (DST) against other drugs. The thin-layer agar (TLA) test, a non-commercial direct DST method, has demonstrated good performance for INH and RMP; however, evidence is still limited, and its applicability for DST of ofloxacin (OFX) and kanamycin (KM) is unknown. We compared 279 TLA DST results with those of MGIT for INH and RMP, and 280 results for OFX and KM with those of the 7H11 agar proportion method, obtained from 320 smear-positive samples from 165 Georgian TB patients. Discrepancies were solved by comparison with a composite reference standard. The prevalence of multidrug-resistant tuberculosis (TB) was 30 of 164 patients (18.3%), 2 (6.7%) of whom had extensively drug-resistant TB. TLA showed 94.7%, 98.2%, 100% and 78.9% sensitivity, respectively, for INH, RMP, OFX and KM, with 100% specificity. Average time to results was 7 days in TLA, 23 in MGIT and 49 for 7H11 agar. In low-resource settings, TLA can be applied for the rapid detection of resistance to INH, RMP and fluoroquinolones. Further studies are necessary to improve sensitivity to KM and further assess its performance for OFX and other drugs and its applicability in field conditions.

A Hidden Pitfall in the Preparation of Agar Media Undermines Microorganism Cultivability

PubMed Central

Tanaka, Tomohiro; Kawasaki, Kosei; Daimon, Serina; Kitagawa, Wataru; Yamamoto, Kyosuke; Tamaki, Hideyuki; Tanaka, Michiko; Nakatsu, Cindy H.

2014-01-01

Microbiologists have been using agar growth medium for over 120 years. It revolutionized microbiology in the 1890s when microbiologists were seeking effective methods to isolate microorganisms, which led to the successful cultivation of microorganisms as single clones. But there has been a disparity between total cell counts and cultivable cell counts on plates, often referred to as the “great plate count anomaly,” that has long been a phenomenon that still remains unsolved. Here, we report that a common practice microbiologists have employed to prepare agar medium has a hidden pitfall: when phosphate was autoclaved together with agar to prepare solid growth media (PT medium), total colony counts were remarkably lower than those grown on agar plates in which phosphate and agar were separately autoclaved and mixed right before solidification (PS medium). We used a pure culture of Gemmatimonas aurantiaca T-27T and three representative sources of environmental samples, soil, sediment, and water, as inocula and compared colony counts between PT and PS agar plates. There were higher numbers of CFU on PS medium than on PT medium using G. aurantiaca or any of the environmental samples. Chemical analysis of PT agar plates suggested that hydrogen peroxide was contributing to growth inhibition. Comparison of 454 pyrosequences of the environmental samples to the isolates revealed that taxa grown on PS medium were more reflective of the original community structure than those grown on PT medium. Moreover, more hitherto-uncultivated microbes grew on PS than on PT medium. PMID:25281372

Comparison of methods for determining the numbers and species distribution of coliform bacteria in well water samples.

PubMed

Niemi, R M; Heikkilä, M P; Lahti, K; Kalso, S; Niemelä, S I

2001-06-01

Enumeration of coliform bacteria and Escherichia coli is the most widely used method in the estimation of hygienic quality of drinking water. The yield of target bacteria and the species composition of different populations of coliform bacteria may depend on the method.Three methods were compared. Three membrane filtration methods were used for the enumeration of coliform bacteria in shallow well waters. The yield of confirmed coliform bacteria was highest on Differential Coliform agar, followed by LES Endo agar. Differential Coliform agar had the highest proportion of typical colonies, of which 74% were confirmed as belonging to the Enterobacteriaceae. Of the typical colonies on Lactose Tergitol 7 TTC agar, 75% were confirmed as Enterobacteriaceae, whereas 92% of typical colonies on LES Endo agar belonged to the Enterobacteriaceae. LES Endo agar yielded many Serratia strains, Lactose Tergitol 7 TTC agar yielded numerous strains of Rahnella aquatilis and Enterobacter, whereas Differential Coliform agar yielded the widest range of species. The yield of coliform bacteria varied between methods. Each method compared had a characteristic species distribution of target bacteria and a typical level of interference of non-target bacteria. Identification with routine physiological tests to distinct species was hampered by the slight differences between species. High yield and sufficient selectivity are difficult to achieve simultaneously, especially if the target group is diverse. The results showed that several aspects of method performance should be considered, and that the target group must be distinctly defined to enable method comparisons.

Use of fatty acid methyl ester profiles for discrimination of Bacillus cereus T-strain spores grown on different media.

PubMed

Ehrhardt, Christopher J; Chu, Vivian; Brown, TeeCie; Simmons, Terrie L; Swan, Brandon K; Bannan, Jason; Robertson, James M

2010-03-01

The goal of this study was to determine if cellular fatty acid methyl ester (FAME) profiling could be used to distinguish among spore samples from a single species (Bacillus cereus T strain) that were prepared on 10 different medium formulations. To analyze profile differences and identify FAME biomarkers diagnostic for the chemical constituents in each sporulation medium, a variety of statistical techniques were used, including nonmetric multidimensional scaling (nMDS), analysis of similarities (ANOSIM), and discriminant function analysis (DFA). The results showed that one FAME biomarker, oleic acid (18:1 omega9c), was exclusively associated with spores grown on Columbia agar supplemented with sheep blood and was indicative of blood supplements that were present in the sporulation medium. For spores grown in other formulations, multivariate comparisons across several FAME biomarkers were required to discern profile differences. Clustering patterns in nMDS plots and R values from ANOSIM revealed that dissimilarities among FAME profiles were most pronounced when spores grown with disparate sources of complex additives or protein supplements were compared (R > 0.8), although other factors also contributed to FAME differences. DFA indicated that differentiation could be maximized with a targeted subset of FAME variables, and the relative contributions of branched FAME biomarkers to group dissimilarities changed when different media were compared. When taken together, these analyses indicate that B. cereus spore samples grown in different media can be resolved with FAME profiling and that this may be a useful technique for providing intelligence about the production methods of Bacillus organisms in a forensic investigation.

Use of Fatty Acid Methyl Ester Profiles for Discrimination of Bacillus cereus T-Strain Spores Grown on Different Media▿

PubMed Central

Ehrhardt, Christopher J.; Chu, Vivian; Brown, TeeCie; Simmons, Terrie L.; Swan, Brandon K.; Bannan, Jason; Robertson, James M.

2010-01-01

The goal of this study was to determine if cellular fatty acid methyl ester (FAME) profiling could be used to distinguish among spore samples from a single species (Bacillus cereus T strain) that were prepared on 10 different medium formulations. To analyze profile differences and identify FAME biomarkers diagnostic for the chemical constituents in each sporulation medium, a variety of statistical techniques were used, including nonmetric multidimensional scaling (nMDS), analysis of similarities (ANOSIM), and discriminant function analysis (DFA). The results showed that one FAME biomarker, oleic acid (18:1 ω9c), was exclusively associated with spores grown on Columbia agar supplemented with sheep blood and was indicative of blood supplements that were present in the sporulation medium. For spores grown in other formulations, multivariate comparisons across several FAME biomarkers were required to discern profile differences. Clustering patterns in nMDS plots and R values from ANOSIM revealed that dissimilarities among FAME profiles were most pronounced when spores grown with disparate sources of complex additives or protein supplements were compared (R > 0.8), although other factors also contributed to FAME differences. DFA indicated that differentiation could be maximized with a targeted subset of FAME variables, and the relative contributions of branched FAME biomarkers to group dissimilarities changed when different media were compared. When taken together, these analyses indicate that B. cereus spore samples grown in different media can be resolved with FAME profiling and that this may be a useful technique for providing intelligence about the production methods of Bacillus organisms in a forensic investigation. PMID:20097814

Removal and mineralization of polycyclic aromatic hydrocarbons by litter-decomposing basidiomycetous fungi.

PubMed

Steffen, K T; Hatakka, A; Hofrichter, M

2002-10-01

Nine strains of litter-decomposing fungi, representing eight species of agaric basidiomycetes, were tested for their ability to remove a mixture of three polycyclic aromatic hydrocarbons (PAHs) (total 60 mg l(-1)) comprising anthracene, pyrene and benzo(a)pyrene (BaP) in liquid culture. All strains were able to convert this mixture to some extent, but considerable differences in degradative activity were observed depending on the species, the Mn(II) concentration, and the particular PAH. Stropharia rugosoannulata was the most efficient degrader, removing or transforming BaP almost completely and about 95% of anthracene and 85% of pyrene, in cultures supplemented with 200 micro M Mn(II), within 6 weeks. In contrast less than 40, 18, and 50% BaP, anthracene and pyrene, respectively, were degraded in the absence of supplemental Mn(II). In the case of Stropharia coronilla, the presence of Mn(II) led to a 20-fold increase of anthracene conversion. The effect of manganese could be attributed to the stimulation of manganese peroxidase (MnP). The maximum activity of MnP increased in S. rugosoannulata cultures from 10 U l(-1) in the absence of Mn(II) to 320 U l(-1) in Mn(II)-supplemented cultures. The latter degraded about 6% of a (14)C-labeled BaP into (14)CO(2) whereas only 0.7% was mineralized in the absence of Mn(II). In solid-state straw cultures, S. rugosoannulata, S. coronilla and Agrocybe praecox mineralized between 4 and 6% of (14)C-labeled BaP within 12 weeks.

Isolation of Cryptococcus neoformans and other opportunistic fungi from pigeon droppings

PubMed Central

Soltani, Maryam; Bayat, Mansour; Hashemi, Seyed J.; Zia, Mohammadali; Pestechian, Nader

2013-01-01

Background: Invasive fungal infections cause considerable morbidity and mortality in immunocompromised hosts. Pigeon droppings could especially be a potential carrier in the spread of pathogenic yeasts and mold fungi into the environment. The objective of this study was to isolation of Cryptococcus neoformans and other opportunistic fungi from pigeon droppings. Materials and Methods: One hundred twenty samples of pigeon droppings were suspended 1:10 in saline solution and then cultured. Identification of C. neoformans was performed on bird seed agar, presence of a capsule on India ink preparation, urease production on urea agar medium and RapID yeast plus system. The identification of candida species was based on micro-morphological analysis on corn meal-Tween 80 agar, RapID yeast plus system and growth in CHROMagar candida. The identification of other fungi was based on macromorphologic, microscopic, biochemical and physiological characteristics. Results: The highest frequency of yeasts and mold fungi were observed in Candida albicans 6.6% and Penicillium spp. 25%. The frequency rate of C. neoformans isolation was 2.5%. Conclusion: Several types of fungi are present in pigeon droppings that can spread in environment and transmit to children and elderly as well as immunocompromised patients who are at increased risk of contracting opportunistic diseases. PMID:23901339

Assessing Pathogen Levels in Dairy Lagoon Wastewater and Potential Evaporation Losses

NASA Astrophysics Data System (ADS)

Pandey, P.; Biswas, S.; Souza, A.; Silva-del-Rio, N.; Vaddella, V. K.; Castillo, A. R.

2014-12-01

The ongoing drought in California necessitates the conservation of existing water resources while protecting the water quality. There is a critical need to improve the understanding of evaporation losses from dairy lagoons in California, and their corresponding changes in pathogen levels in the lagoon wastewater. We have carried out preliminary studies involving extensive dairy lagoon water sampling, and batch-scale experiments. The dairy wastewater was collected from both primary and secondary lagoons in three counties of California (Merced, Tulare, and Glenn Counties) for enumerating the levels of E. coli O157:H7, Salmonella spp., and Listeria monocytogenes. Subsequently, we conducted batch-scale experiments at mesophilic (31 and 37 ⁰C) and thermophilic temperatures (43 and 49 ⁰C) to understand the E. coli O157:H7 inactivation process and potential evaporative water losses. In addition, we compared the evaporation losses under the environment of biological activity and the environment of restricted biological activity (extreme environment with low pH). For E. coli O157:H7 enumeration, we used MacConkey agar, while for Salmonella spp., XLD agar was used. Listeria monocytogenes levels were measured using PALCAM agar (with selective supplement). In flushed dairy wastewater (fresh) samples, the average of E. coli O157:H7 levels were 2 × 104 CFU/mL. The average Listeria monocytogenes levels in flushed manure were 9 × 101. The levels of Salmonella spp. were non-detectable. In mesophilic condition (37 ⁰C) after 5 days of incubation, 8% of total water loss was observed, while at thermophilic temperature (49 ⁰C), 70% of total water loss was observed. After 5 days of incubation at 37 ⁰C, E. coli O157:H7 levels in flushed dairy manure were increased from 2.8 × 103 to 5.2 × 104 CFU/mL, while at 49 ⁰C, E. coli O157:H7 levels were reduced from 2.8 × 103 to 5 × 101 CFU/mL after 4 days of incubation. We anticipate that the results of this study would be useful in understanding the dynamics of water losses and pathogen inactivation in dairy lagoon wastewater.

Micropropagation of an exotic ornamental plant, Calathea crotalifera, for production of high quality plantlets.

PubMed

Rozali, Shahril Efzueni; Rashid, Kamaludin A; Taha, Rosna Mat

2014-01-01

A successful protocol was established for micropropagation in two selected varieties of exotic ornamental plants, Calathea crotalifera. The effects of different sterilization techniques, explant type, and the combination and concentration of plant growth regulators on shoots induction were studied. The axillary shoot buds explants sprouted from rhizomes in soil free conditions showed high induction rate of shoots with lowest contamination percentage when treated with combination of 30% (v/v) NaOCl, 70% (v/v) ethanol, and 0.3% (w/v) HgCl2. In the present study, the highest number of multiple shoots was obtained in MS basal medium supplemented with 3.5 mg/L 6-Benzylaminopurine (BAP), 1.0 mg/L 1-Naphthaleneacetic acid (NAA), 3% sucrose, and 6 g/L plant agar for both varieties and was used as multiplication medium. Microshoots were highly induced when the young shoot bud explants were incised longitudinally prior subculture. Chlorophyll analysis was studied to test the effects of activated charcoal and L-glutamine on reduction of necrosis problem. The maximum roots induction was recorded on MS medium supplemented with 1.0 mg/L 1-Naphthaleneacetic acid (NAA) compared to indolebutyric acid (IBA). The complete regenerated plantlets were successfully acclimatized in the soilless medium under greenhouse condition. This is the first report of rapid mass propagation for C. crotalifera.

Trametes meyenii possesses elevated dye degradation abilities under normal nutritional conditions compared to other white rot fungi

PubMed Central

2014-01-01

Several species of white-rot fungi were investigated for their utility in prolonged decolouration of the recalcitrant sulfonated azo dye, amaranth. Trametes pubescens, T. multicolor, T. meyenii and T. versicolor decoloured amaranth azo-dye best on low-nitrogen agar-solidified media whereas Bjerkandera adusta and Phlebia radiata were most effective in low nitrogen medium supplemented with manganese. Trametes cotonea did not decolour effectively under any condition. The decolouring Trametes species were also effective in liquid culture whereas B. adusta and P. radiata were not. Trametes meyenii, T. pubescens and T. multicolor were equal to or better than commonly employed T. versicolor at decolouring amaranth. This is the first study to show the dye decolouration potential of T. meyenii, T. pubescens, and T. multicolor. Supplementing with Mn(II) increased assayable manganese peroxidase activity, but not long-term decolouration, indicating that laccase is the main decolourizing enzyme in these Trametes species. This appears to be because of inadequate Mn3+ chelation required by manganese peroxidase because adding relatively low amounts of malonate enhanced decolouration rates. The ability of Trametes meyenii to simultaneously decolour dye over prolonged periods of time while growing in relatively nutrient-rich medium appears to be unique amongst white-rot fungi, indicating its potential in wastewater bioremediation. PMID:25401075

Effect of Sodium Fluorescein and Plating Medium on Recovery of Irradiated Escherichia coli and Serratia marcescens from Aerosols

PubMed Central

Dorsey, Emerson L.; Berendt, Richard F.; Neff, Everett L.

1970-01-01

Irradiation of aerosols of either Escherichia coli or Serratia marcescens with simulated solar (xenon) radiation caused a significant decrease in viability. When sodium fluorescein was employed to determine the physical loss of organisms from the aerosol, an additional adverse effect upon survival was noted. The decay curves indicated that at least two mechanisms of inactivation were operative, one due to aerosolization, the other to irradiation. After collection from aerosols, both species of microorganisms grew better on blood agar base than on Casitone agar, but this finding did not appear to be related to the effect of irradiation. PMID:4922085

Clinical test to detect mecA and antibiotic resistance in Staphylococcus aureus, based on novel biotechnological methods.

PubMed

Shahmohammadi, Mohammad Reza; Nahaei, Mohammad Reza; Akbarzadeh, Abolfazl; Milani, Morteza

2016-09-01

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common organisms isolated from clinical samples, and has been associated with morbidity and mortality among hospitalized patients. The aim of this study was to evaluate the prevalence and antibiotic susceptibility patterns among MRSA and methicillin-sensitive S. aureus (MSSA) isolates collected from four hospitals in Iran. A total of 183 isolates of S. aureus were collected from various clinical specimens of four hospitals in Iran. The isolates were identified by using the conventional biochemical tests. Three methods-oxacillin agar disk diffusion, oxacillin agar screening, and PCR- were applied to determine susceptibility to oxacillin. The conventional disk agar diffusion test was used to evaluate the antibiotic sensitivity of our isolates against 15 antibiotics, according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Of 183 isolates, 77 isolates (42.1%) were found to be MRSA, by the PCR method. The highest antibiotic resistance was found to be against penicillin, co-trimoxazole, erythromycin, and tetracycline respectively. All isolates were susceptible to vancomycin, according to the results of disk agar diffusion. Among other antibiotics, teicoplanin (84%) and fusidic acid (80.5%) were more active against MRSA isolates. For the different methods evaluated, the sensitivities and specificities were as follows: for disk agar diffusion (84.9% and 95.9%) and for agar screening test with oxacillin concentrations of 0.6 μg/ml (70.8% and 97.4%), 4 μg/ml (96.1%and 97.2%) and 6 μg/ml (96% and 96.3%), respectively. The results of our study showed that 47% of S. aureus isolates were MRSA. Overall, in this research study, resistance to all test antimicrobial agents in MRSA isolates were higher than that of MSSA isolates. Our results also revealed that 85% of mecA-positive isolates and 15% of mecA-negative isolates were resistant to methicillin; while 96% of mecA-negative isolates were sensitive to methicillin. Meanwhile 4% of mecA-positive isolates were also sensitive to methicillin.

Comparison of Performance of the Novel Chromogenic Spectra VRE Agar to That of Bile Esculin Azide and Campylobacter Agars for Detection of Vancomycin-Resistant Enterococci in Fecal Samples ▿

PubMed Central

Jenkins, S. G.; Raskoshina, L.; Schuetz, A. N.

2011-01-01

A total of 142 stool specimens were evaluated for vancomycin-resistant enterococcus (VRE). Twenty-four-hour sensitivities and specificities, respectively, were 98% and 95% for Spectra VRE chromogenic agar (Remel, Lenexa, KS), 86% and 92% for bile esculin azide with vancomycin (BEAV; Remel), and 96.5% and 92% for Campylobacter agar (CAMPY; Remel). Spectra VRE and CAMPY are significantly more sensitive at 24 h than BEAV. PMID:21880967

Evaluation of Granada agar plate for detection of Streptococcus agalactiae in urine specimens from pregnant women.

PubMed

Tamayo, Javier; Gómez-Garcés, José-Luis; Alós, Juan-Ignacio

2004-08-01

The Granada agar plate (GAP; Biomedics SL, Madrid, Spain) was evaluated for the detection of group B streptococci (GBS) in urine specimens from pregnant women submitted for testing for asymptomatic bacteriuria and was compared with blood agar (BA [Columbia agar with 5% sheep blood]; bioMérieux, Marcy l'Etoile, France). The GAP detected 103 out of 105 GBS, whereas BA detected only 50. Use of the GAP could be a good method for the detection of GBS in urine specimens from pregnant women.

Studies on prevalence of Strongyloides infection in Holambra and Maceió, Brazil, by the agar plate faecal culture method.

PubMed

Kobayashi, J; Hasegawa, H; Soares, E C; Toma, H; Dacal, A R; Brito, M C; Yamanaka, A; Foli, A A; Sato, Y

1996-01-01

Prevalence of Strongyloides stercoralis infection in three areas of Brazil was surveyed by a recently developed faecal culture method (an agar plate culture). The Strongyloides infection was confirmed in 11.3% of 432 subjects examined. The diagnostic efficacy of the agar plate culture was as high as 93.9% compared to only 28.5% and 26.5% by the Harada-Mori filter paper culture and faecal concentration methods, when faecal samples were examined simultaneously by these three methods. Among the 49 positive samples, about 60% were confirmed to be positive only by the agar plate culture. These results indicate that the agar plate culture is a sensitive new tool for the correct diagnosis of chronic Strongyloides infection.

A fresh liver agar substrate for rearing small numbers of forensically important blow flies (Diptera: Calliphoridae).

PubMed

Gruner, Susan V; Slone, Daniel H

2014-05-01

Forensically important calliphorids can be reared on a mixture of beef liver and agar. Small pieces of meat, especially fresh or frozen beef liver, will desiccate in 2-6 h, but this simple-to-make feeding substrate remains moist for at least 12 h at 25 and 30 degrees C without desiccation, even in small (5 g) amounts. We determined the survivorship of small numbers of Chrysomya megacephala (F.) (first-instar larvae to adult eclosion) raised on 5 g of liver agar and fresh beef liver. We found that all larvae raised on 5 g of liver died due to desiccation, but survivorship on 5 g of liver agar was equivalent to that on larger (50 g) pieces of either liver agar or beef liver.

Usefulness of Chromogenic CromoCen® AGN agar medium for the identification of the genus Aeromonas: Assessment of faecal samples.

PubMed

Aguilera-Arreola, M G; Portillo-Muñoz, M I; Rodríguez-Martínez, C; Castro-Escarpulli, G

2012-08-01

Selective screening media for the detection and identification of Aeromonas strains are needed to guide primary isolation procedures in the clinical laboratory. This study compared the selective CromoCen® AGN chromogenic agar medium for the detection and identification of Aeromonas strains that were isolated from various samples against the conventional selective agar media that are commonly used for the isolation of this organism in food, environmental and clinical samples. The Miles and Misra and ecometric methods were used to evaluate the microbiological performance of CromoCen® AGN chromogenic agar medium, which was shown to be satisfactory. A total of 14 reference Aeromonas strains, 44 wild strains and 106 clinical stool specimens were examined using both non-chromogenic selective agars that are commonly used for Aeromonas isolation and CromoCen® AGN agar. The latter exhibited 94.73% sensitivity and 100% specificity for the various samples. On CromoCen® AGN agar medium, Aeromonas formed colonies with light green, greenish and salmon pigments with or without a surrounding wide transparent zone (halo) of 2-3mm in diameter around the entire border. This medium is recommended for the isolation and potential identification of the Aeromonas genus. Copyright © 2012 Elsevier B.V. All rights reserved.

Use of an agar-gel technique for large scale application to recover Ascaris suum larvae from intestinal contents of pigs.

PubMed

Slotved, H C; Barnes, E H; Eriksen, L; Roepstorff, A; Nansen, P; Bjørn, H

1997-01-01

Four groups each of 3 pigs were inoculated with Ascaris suum eggs. Pigs in groups 1 and 3 were inoculated with 1000 eggs, and pigs in groups 2 and 4 with 10,000 eggs. On day 10 and 21 post-inoculation (p.i.), respectively, groups 1 + 2 and 3 + 4 were slaughtered, and the contents from the small intestines collected. The contents were mixed with agar to a final concentration of 1% agar and allowed to sediment. The larvae were allowed to migrate from the agar-gel into 38 degrees C 0.9% saline overnight, and were then collected on a sieve (20 microns mesh) and counted. The larvae retained in the agar-gel were counted after pouring the melted agar through a sieve (20 microns mesh). The results showed that more than 97% of the larvae migrated out of the agar-gel and were available for counting in an almost clean suspension. The inoculation dose level did not significantly affect the recovery percentage, neither did the larval stage (10 or 21 days old larvae). The variation in the time interval from slaughtering to start of incubation (interval 57-155 min) did not significantly affect the recovery percentage.

Evaluation of standard and modified M-FC, MacConkey, and Teepol media for membrane filtration counting of fecal coliforms in water.

PubMed

Grabow, W O; Hilner, C A; Coubrough, P

1981-08-01

MacConkey agar, standard M-FC agar, M-FC agar without rosolic acid, M-FC agar with a resuscitation top layer, Teepol agar, and pads saturated with Teepol broth, were evaluated as growth media for membrane filtration counting of fecal coliform bacteria in water. In comparative tests on 312 samples of water from a wide variety of sources, including chlorinated effluents, M-FC agar without rosolic acid proved the medium of choice because it generally yielded the highest counts, was readily obtainable, easy to prepare and handle, and yielded clearly recognizable fecal coliform colonies. Identification of 1,139 fecal coliform isolates showed that fecal coliform tests cannot be used to enumerate Escherichia coli because the incidence of E. coli among fecal coliforms varied from an average of 51% for river water to 93% for an activated sludge effluent after chlorination. The incidence of Klebsiella pneumoniae among fecal coliforms varied from an average of 4% for the activated sludge effluent after chlorination to 32% for the river water. The advantages of a standard membrane filtration procedure for routine counting of fecal coliforms in water using M-FC agar without rosolic acid as growth medium, in the absence of preincubation or resuscitation steps, are outlined.

Performance of the EUCAST Disk Diffusion Method, the CLSI Agar Screen Method, and the Vitek 2 Automated Antimicrobial Susceptibility Testing System for Detection of Clinical Isolates of Enterococci with Low- and Medium-Level VanB-Type Vancomycin Resistance: a Multicenter Study

PubMed Central

Giske, Christian G.; Haldorsen, Bjørg; Matuschek, Erika; Schønning, Kristian; Leegaard, Truls M.; Kahlmeter, Gunnar

2014-01-01

Different antimicrobial susceptibility testing methods to detect low-level vancomycin resistance in enterococci were evaluated in a Scandinavian multicenter study (n = 28). A phenotypically and genotypically well-characterized diverse collection of Enterococcus faecalis (n = 12) and Enterococcus faecium (n = 18) strains with and without nonsusceptibility to vancomycin was examined blindly in Danish (n = 5), Norwegian (n = 13), and Swedish (n = 10) laboratories using the EUCAST disk diffusion method (n = 28) and the CLSI agar screen (n = 18) or the Vitek 2 system (bioMérieux) (n = 5). The EUCAST disk diffusion method (very major error [VME] rate, 7.0%; sensitivity, 0.93; major error [ME] rate, 2.4%; specificity, 0.98) and CLSI agar screen (VME rate, 6.6%; sensitivity, 0.93; ME rate, 5.6%; specificity, 0.94) performed significantly better (P = 0.02) than the Vitek 2 system (VME rate, 13%; sensitivity, 0.87; ME rate, 0%; specificity, 1). The performance of the EUCAST disk diffusion method was challenged by differences in vancomycin inhibition zone sizes as well as the experience of the personnel in interpreting fuzzy zone edges as an indication of vancomycin resistance. Laboratories using Oxoid agar (P < 0.0001) or Merck Mueller-Hinton (MH) agar (P = 0.027) for the disk diffusion assay performed significantly better than did laboratories using BBL MH II medium. Laboratories using Difco brain heart infusion (BHI) agar for the CLSI agar screen performed significantly better (P = 0.017) than did those using Oxoid BHI agar. In conclusion, both the EUCAST disk diffusion and CLSI agar screening methods performed acceptably (sensitivity, 0.93; specificity, 0.94 to 0.98) in the detection of VanB-type vancomycin-resistant enterococci with low-level resistance. Importantly, use of the CLSI agar screen requires careful monitoring of the vancomycin concentration in the plates. Moreover, disk diffusion methodology requires that personnel be trained in interpreting zone edges. PMID:24599985

Antimicrobial activity of highly stable silver nanoparticles embedded in agar-agar matrix as a thin film.

PubMed

Ghosh, S; Kaushik, R; Nagalakshmi, K; Hoti, S L; Menezes, G A; Harish, B N; Vasan, H N

2010-10-13

Highly stable silver nanoparticles (Ag NPs) in agar-agar (Ag/agar) as inorganic-organic hybrid were obtained as free-standing film by in situ reduction of silver nitrate by ethanol. The antimicrobial activity of Ag/agar film on Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans) was evaluated in a nutrient broth and also in saline solution. In particular, films were repeatedly tested for antimicrobial activity after recycling. UV-vis absorption and TEM studies were carried out on films at different stages and morphological studies on microbes were carried out by SEM. Results showed spherical Ag NPs of size 15-25 nm, having sharp surface plasmon resonance (SPR) band. The antimicrobial activity of Ag/agar film was found to be in the order, C. albicans>E. coli>S. aureus, and antimicrobial activity against C. albicans was almost maintained even after the third cycle. Whereas, in case of E. coli and S. aureus there was a sharp decline in antimicrobial activity after the second cycle. Agglomeration of Ag NPs in Ag/agar film on exposure to microbes was observed by TEM studies. Cytotoxic experiments carried out on HeLa cells showed a threshold Ag NPs concentration of 60 μg/mL, much higher than the minimum inhibition concentration of Ag NPs (25.8 μg/mL) for E. coli. The mechanical strength of the film determined by nanoindentation technique showed almost retention of the strength even after repeated cycle. Copyright © 2010 Elsevier Ltd. All rights reserved.

Correlation between mastitis occurrence and the count of microorganisms in bulk raw milk of bovine dairy herds in four selective culture media.

PubMed

Souto, Luís I M; Minagawa, Clarice Y; Telles, Evelise O; Garbuglio, Márcio A; Amaku, Marcos; Melville, Priscilla A; Dias, Ricardo A; Sakata, Sonia T; Benites, Nilson R

2010-02-01

Milk is the normal secretion of the mammary gland, practically free of colostrum and obtained by the complete milking of one or more healthy animals. Mastitis is an inflammatory process of the mammary gland and it may cause alterations in the milk. The present work aimed to verify whether it is possible, by means of the counts of microorganism in the bulk raw milk in four selective culture media, to establish a correlation with the occurrence of mastitis and therefore, to monitor this disease in bovine dairy herds. The following selective culture media were used: KF Streptococcus Agar, Edwards Agar, Baird-Parker Agar, Blood Agar plus potassium tellurite. Spearman's correlation coefficient was calculated in order to compare the occurrence of mastitis (percentage) in each herd with respective selective culture media counts of microorganisms in bulk raw milk. Thirty-six possibilities were analysed (Tamis and CMT-positive rates were compared with the log-transformed count in four selective culture media) and there was a negative correlation between Tamis 3 and the Baird-Parker Agar plate count. The total results of microbiological tests showed that there were three correlations of the counts in selective culture media. Fifty-two possibilities were analysed and there was a negative correlation between no-bacterial-growth mastitis rates and log10 of KF Streptoccocus Agar plate count and there were two positive correlations between coagulase-positive staphylococci and log10 of Baird-Parker Agar plate count and Blood Agar plus potassium tellurite plate count.

Alternative Differential Identification Approaches for 2 Similar Bacilli Commonly Studied in Microbiology.

ERIC Educational Resources Information Center

Benathen, Isaiah A.

1991-01-01

Alternatives to the traditional unknown tests that permit a clear and unequivocal differential identification decision between Bacillus subtilis and Bacillus megaterium are presented. Plates of Phenylethyl Alcohol agar with Blood (PEAB), slants of Bile Esculin agar and plates of DNA agar are used. The materials, methods, results, and conclusions…

RELATIONSHIPS BETWEEN LEVELS OF HETEROTROPHIC BACTERIA AND WATER QUALITY PARAMETERS IN A DRINKING WATER DISTRIBUTION SYSTEM

EPA Science Inventory

Conventional plating methods were used to quantify heterotrophic bacteria from a drinking water distribution system. Three media, plate count agar (PCA), R2A agar and sheep blood agar (TSA-SB) were used to determine heterotrophic plate count (HPC) levels. Grab samples were collec...

Anti-L. donovani activity in macrophage/amastigote model of palmarumycin CP18 and its large scale production.

PubMed

Ortega, Humberto E; Teixeira, Eliane de Morais; Rabello, Ana; Higginbotham, Sarah; Cubilla-Ríos, Luis

2014-01-01

Palmarumycin CP18, isolated from an extract of the fermentation broth and mycelium of the Panamanian endophytic fungus Edenia sp., was previously reported with strong and specific activity against Leishmania donovani. Here we report that when the same strain was cultured on different solid media--Harrold Agar, Leonian Agar, Potato dextrose Agar (PDA), Corn Meal Agar, Honey Peptone Agar, and eight vegetables (V8) Agar--in order to determine the optimal conditions for isolation of palmarumycin CP18, no signal for this compound was observed in any of the 1H NMR spectra of fractions obtained from these extracts. However, one extract, prepared from the fungal culture in PDA contained significant amounts of CJ-12,372, a possible biosynthetic precursor of palmarumycin CP18. Edenia sp. was cultivated on a large scale on PDA and CJ-12,372 was converted to palmarumycin CP18 by oxidation of its p-hydroquinone moiety with DDQ in dioxane. Palmarumycin CP18 showed anti-leishmanial activity against L. donovani in a macrophage/amastigote model, with IC50 values of 23.5 microM.

Evaluation of Sterilized Artificial Diets for Mass Rearing the Lucilia sericata (Diptera: Calliphoridae).

PubMed

Zheng, Le; Crippen, Tawni L; Dabney, Alan; Gordy, Alex; Tomberlin, Jeffery K

2017-09-01

The impact of six sterilized diets (blood-yeast agar diet, decomposed beef liver diet, powdered beef liver diet, powdered fish diet, milk-based diet, and a chemically defined diet) on Lucilia sericata (Meigen) larvae reared at three densities (10 larvae, 20 larvae, and 40 larvae on 20 g diet) was determined in comparison to fresh beef liver as a control. Specifically, the effects of these diets on the following traits of L. sericata were measured: 1) pupal weight, 2) pupation percentage, 3) eclosion percentage, as well as 4) adult longevity. The experiment included two trials with five technical replicates in each. Lucilia sericata did not successfully develop on the powdered fish, milk-based, or chemically defined diets. Overall, the liver-based diets (decomposed and powdered) resulted in the most similar fly development to the fresh beef liver. Larvae reared on blood-yeast agar diet resulted in a significantly (increased 20.56% ± 8.09%) greater pupation rate than those reared on the decomposed and powdered beef liver diets. Pupae from larvae fed the fresh beef liver were significantly larger (6.27 ± 1.01 mg, 4.05 ± 0.94 mg larger, respectively) than those reared on the blood-yeast agar diet, decomposed beef liver, and powdered beef liver diets. Overall, results revealed larvae reared on sterilized liver-based diets resulted in traits similar to those raised on fresh beef liver. Owing to low costs the sterile liver-based diets could be produced and used with limited infrastructure and economic incomes. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Preparation of an agar-silver nanoparticles (A-AgNp) film for increasing the shelf-life of fruits.

PubMed

Gudadhe, Janhavi A; Yadav, Alka; Gade, Aniket; Marcato, Priscyla D; Durán, Nelson; Rai, Mahendra

2014-12-01

Preparation of protective coating possessing antimicrobial properties is present day need as they increase the shelf life of fruits and vegetables. In the present study, preparation of agar-silver nanoparticle film for increasing the shelf life of fruits is reported. Silver nanoparticles (Ag-NPs) biosynthesised using an extract of Ocimum sanctum leaves, were mixed with agar-agar to prepare an agar-silver nanoparticles (A-AgNp) film. This film was surface-coated over the fruits, Citrus aurantifolium (Thornless lime) and Pyrus malus (Apple), and evaluated for the determination of antimicrobial activity of A-AgNp films using disc diffusion method, weight loss and shelf life of fruits. This study demonstrates that these A-AgNp films possess antimicrobial activity and also increase the shelf life of fruits.

A fresh liver agar substrate for rearing small numbers of forensically important blow flies (Diptera: Calliphoridae)

USGS Publications Warehouse

Gruner, Susan V.; Slone, Daniel H.

2014-01-01

Forensically important calliphorids can be reared on a mixture of beef liver and agar. Small pieces of meat, especially fresh or frozen beef liver, will desiccate in 2–6 h, but this simple-to-make feeding substrate remains moist for at least 12 h at 25 and 30°C without desiccation, even in small (5 g) amounts. We determined the survivorship of small numbers of Chrysomya megacephala (F.) (first-instar larvae to adult eclosion) raised on 5 g of liver agar and fresh beef liver. We found that all larvae raised on 5 g of liver died due to desiccation, but survivorship on 5 g of liver agar was equivalent to that on larger (50 g) pieces of either liver agar or beef liver.

Proton beam writing of microstructures in Agar gel for patterned cell growth

NASA Astrophysics Data System (ADS)

Larisch, Wolfgang; Koal, Torsten; Werner, Ronald; Hohlweg, Marcus; Reinert, Tilo; Butz, Tilman

2011-10-01

A rather useful prerequisite for many biological and biophysical studies, e.g., for cell-cell communication or neuronal networks, is confined cell growth on micro-structured surfaces. Solidified Agar layers have smooth surfaces which are electrically neutral and thus inhibit receptor binding and cell adhesion. For the first time, Agar microstructures have been manufactured using proton beam writing (PBW). In the irradiated Agar material the polysaccharides are split into oligosaccharides which can easily be washed off leaving Agar-free areas for cell adhesion. The beam diameter of 1 μm allows the fabrication of compartments accommodating single cells which are connected by micrometer-sized channels. Using the external beam the production process is very fast. Up to 50 Petri dishes can be produced per day which makes this technique very suitable for biological investigations which require large throughputs.

A Multilaboratory, Multicountry Study To Determine Bedaquiline MIC Quality Control Ranges for Phenotypic Drug Susceptibility Testing

PubMed Central

Cirillo, Daniela M.; Hoffner, Sven; Ismail, Nazir A.; Kaur, Devinder; Lounis, Nacer; Metchock, Beverly; Pfyffer, Gaby E.; Venter, Amour

2016-01-01

The aim of this study was to establish standardized drug susceptibility testing (DST) methodologies and reference MIC quality control (QC) ranges for bedaquiline, a diarylquinoline antimycobacterial, used in the treatment of adults with multidrug-resistant tuberculosis. Two tier-2 QC reproducibility studies of bedaquiline DST were conducted in eight laboratories using Clinical Laboratory and Standards Institute (CLSI) guidelines. Agar dilution and broth microdilution methods were evaluated. Mycobacterium tuberculosis H37Rv was used as the QC reference strain. Bedaquiline MIC frequency, mode, and geometric mean were calculated. When resulting data occurred outside predefined CLSI criteria, the entire laboratory data set was excluded. For the agar dilution MIC, a 4-dilution QC range (0.015 to 0.12 μg/ml) centered around the geometric mean included 95.8% (7H10 agar dilution; 204/213 observations with one data set excluded) or 95.9% (7H11 agar dilution; 232/242) of bedaquiline MICs. For the 7H9 broth microdilution MIC, a 3-dilution QC range (0.015 to 0.06 μg/ml) centered around the mode included 98.1% (207/211, with one data set excluded) of bedaquiline MICs. Microbiological equivalence was demonstrated for bedaquiline MICs determined using 7H10 agar and 7H11 agar but not for bedaquiline MICs determined using 7H9 broth and 7H10 agar or 7H9 broth and 7H11 agar. Bedaquiline DST methodologies and MIC QC ranges against the H37Rv M. tuberculosis reference strain have been established: 0.015 to 0.12 μg/ml for the 7H10 and 7H11 agar dilution MICs and 0.015 to 0.06 μg/ml for the 7H9 broth microdilution MIC. These methodologies and QC ranges will be submitted to CLSI and EUCAST to inform future research and provide guidance for routine clinical bedaquiline DST in laboratories worldwide. PMID:27654337

Study on the application of shear-wave elastography to thin-layered media and tubular structure: Finite-element analysis and experiment verification

NASA Astrophysics Data System (ADS)

Jang, Jun-keun; Kondo, Kengo; Namita, Takeshi; Yamakawa, Makoto; Shiina, Tsuyoshi

2016-07-01

Shear-wave elastography (SWE) enables the noninvasive and quantitative evaluation of the mechanical properties of human soft tissue. Generally, shear-wave velocity (C S) can be estimated using the time-of-flight (TOF) method. Young’s modulus is then calculated directly from the estimated C S. However, because shear waves in thin-layered media propagate as guided waves, C S cannot be accurately estimated using the conventional TOF method. Leaky Lamb dispersion analysis (LLDA) has recently been proposed to overcome this problem. In this study, we performed both experimental and finite-element (FE) analyses to evaluate the advantages of LLDA over TOF. In FE analysis, we investigated why the conventional TOF is ineffective for thin-layered media. In phantom experiments, C S results estimated using the two methods were compared for 1.5 and 2% agar plates and tube phantoms. Furthermore, it was shown that Lamb waves can be applied to tubular structures by extracting lateral waves traveling in the long axis direction of the tube using a two-dimensional window. Also, the effects of the inner radius and stiffness (or shear wavelength) of the tube on the estimation performance of LLDA were experimentally discussed. In phantom experiments, the results indicated good agreement between LLDA (plate phantoms of 2 mm thickness: 5.0 m/s for 1.5% agar and 7.2 m/s for 2% agar; tube phantoms with 2 mm thickness and 2 mm inner radius: 5.1 m/s for 1.5% agar and 7.0 m/s for 2% agar; tube phantoms with 2 mm thickness and 4 mm inner radius: 5.3 m/s for 1.5% agar and 7.3 m/s for 2% agar) and SWE measurements (bulk phantoms: 5.3 m/s ± 0.27 for 1.5% agar and 7.3 m/s ± 0.54 for 2% agar).

Culture Phenotypes of Genomically and Geographically Diverse Mycobacterium avium subsp. paratuberculosis Isolates from Different Hosts▿

PubMed Central

Whittington, Richard J.; Marsh, Ian B.; Saunders, Vanessa; Grant, Irene R.; Juste, Ramon; Sevilla, Iker A.; Manning, Elizabeth J. B.; Whitlock, Robert H.

2011-01-01

Mycobacterium avium subsp. paratuberculosis causes paratuberculosis (Johne's disease) in ruminants in most countries. Historical data suggest substantial differences in culturability of M. avium subsp. paratuberculosis isolates from small ruminants and cattle; however, a systematic comparison of culture media and isolates from different countries and hosts has not been undertaken. Here, 35 field isolates from the United States, Spain, Northern Ireland, and Australia were propagated in Bactec 12B medium and Middlebrook 7H10 agar, genomically characterized, and subcultured to Lowenstein-Jensen (LJ), Herrold's egg yolk (HEY), modified Middlebrook 7H10, Middlebrook 7H11, and Watson-Reid (WR) agars, all with and without mycobactin J and some with sodium pyruvate. Fourteen genotypes of M. avium subsp. paratuberculosis were represented as determined by BstEII IS900 and IS1311 restriction fragment length polymorphism analysis. There was no correlation between genotype and overall culturability, although most S strains tended to grow poorly on HEY agar. Pyruvate was inhibitory to some isolates. All strains grew on modified Middlebrook 7H10 agar but more slowly and less prolifically on LJ agar. Mycobactin J was required for growth on all media except 7H11 agar, but growth was improved by the addition of mycobactin J to 7H11 agar. WR agar supported the growth of few isolates. The differences in growth of M. avium subsp. paratuberculosis that have historically been reported in diverse settings have been strongly influenced by the type of culture medium used. When an optimal culture medium, such as modified Middlebrook 7H10 agar, is used, very little difference between the growth phenotypes of diverse strains of M. avium subsp. paratuberculosis was observed. This optimal medium is recommended to remove bias in the isolation and cultivation of M. avium subsp. paratuberculosis. PMID:21430104

Yeast ecology of Kombucha fermentation.

PubMed

Teoh, Ai Leng; Heard, Gillian; Cox, Julian

2004-09-01

Kombucha is a traditional fermentation of sweetened tea, involving a symbiosis of yeast species and acetic acid bacteria. Despite reports of different yeast species being associated with the fermentation, little is known of the quantitative ecology of yeasts in Kombucha. Using oxytetracycline-supplemented malt extract agar, yeasts were isolated from four commercially available Kombucha products and identified using conventional biochemical and physiological tests. During the fermentation of each of the four products, yeasts were enumerated from both the cellulosic pellicle and liquor of the Kombucha. The number and diversity of species varied between products, but included Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, Torulaspora delbrueckii and Zygosaccharomyces bailii. While these yeast species are known to occur in Kombucha, the enumeration of each species present throughout fermentation of each of the four Kombucha cultures demonstrated for the first time the dynamic nature of the yeast ecology. Kombucha fermentation is, in general, initiated by osmotolerant species, succeeded and ultimately dominated by acid-tolerant species.

Amyloplasts as possible statoliths in gravitropic protonemata of the moss Ceratodon purpureus

NASA Technical Reports Server (NTRS)

Walker, L. M.; Sack, F. D.

1990-01-01

The kinetics of gravitropism and of amyloplast sedimentation were studied in dark-grown protonemata of the moss Ceratodon purpureus (Hedw.) Brid. The protonemata grew straight up at a rate of 20-25 micromoles h-1 in nutrient-supplemented agar. After they were oriented to the horizontal, upward curvature was first detected after 1-1.5 h and reached 84 degrees by 24 h. The tip cells exhibited an amyloplast zonation, with a tip cluster of non-sedimenting amyloplasts, an amyloplast-free zone, and a zone with pronounced amyloplast sedimentation. This latter zone appears specialized more for lateral than for axial sedimentation since amyloplasts sediment to the lower wall in horizontal protonemata but do not fall to the basal wall in vertical protonemata. Amyloplast sedimentation started within 15 min of gravistimulation; this is within the 12-17-min presentation time. The data support the hypothesis that some amyloplasts function as statoliths in these cells.

Vancomycin resistant Enterococcus spp. from crows and their environment in metropolitan Washington State, USA: Is there a correlation between VRE positive crows and the environment?

PubMed

Roberts, Marilyn C; No, David B; Marzluff, John M; Delap, Jack H; Turner, Robert

2016-10-15

Vancomycin-resistant enterococci [VRE] have been isolated from municipal, hospital and agricultural wastewater, recreational beaches, wild animals, birds and food animals around the world. In this study, American crows (Corvus brachyrhynchos) from sewage treatment plants (WWTP), dairy farms, and a large roost in a restored wetland with corresponding environmental samples were cultured for VRE. A total of 245 samples [156 crows, 89 environmental] were collected and screened for acquired vanA, vanB and/or intrinsic vanC1 genes. Samples were enriched overnight in BHI supplemented with 20μg/mL aztreonam, 4μg/mL vancomycin and plated on m-Enterococcus agar media supplemented with 6μg/mL vancomycin. Selected colonies were grown on BHI media supplemented with 18μg/mL vancomycin. Of these, 24.5% of the crow and 55% the environmental/cow samples were VRE positive as defined by Enterococcus spp. able to grow on media supplemented with 18μg/mL vancomycin. A total of 122 VRE isolates, 43 crow and 79 environmental isolates were screened, identified to species level using 16S sequencing and further characterized. Four vanA E. faecium and multiple vanC1 E. gallinarum were identified from crows isolated from three sites. E. faecium vanA and E. gallinarum vanC1 along with other Enterococcus spp. carrying vanA, vanB, vanC1 were isolated from three environments. All enterococci were multidrug resistant. Crows were more likely to carry vanA E. faecium than either the cow feces or wetland waters/soils. Comparing E. gallinarum vanC1 from crows and their environment would be useful in determining whether crows share VRE strains with their environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Xanthan gum: an economical substitute for agar in plant tissue culture media.

PubMed

Jain, R; Babbar, S B

2006-03-01

Xanthan gum, a microbial desiccation-resistant polysaccharide prepared commercially by aerobic submerged fermentation from Xanthomonas campestris, has been successfully used as a solidifying agent for plant tissue culture media. Its suitability as a substitute to agar was demonstrated for in vitro seed germination, caulogenesis and rhizogenesis of Albizzia lebbeck, androgenesis in anther cultures of Datura innoxia, and somatic embryogenesis in callus cultures of Calliandra tweedii. Culture media used for eliciting these morphogenic responses were gelled with either 1% xanthan gum or 0.9% agar. Xanthan gum, like agar, supported all these responses.

Morphological Variations in Conidia of Arthrobotrys oligospora on Different Media.

PubMed

Singh, R K; Kumar, Niranjan; Singh, K P

2005-06-01

Most commonly occurring predacious fungus Arthrobotrys oligospora showed great variation in size and shape of conidia on some media. The formation of larger conidia was recorded on beef extract and nutrient agar media. The length of conidia in Richard's YPSS, Sabouraud's, PDA and corn meal agar media was of medium size while smaller conidia were produced on Czapek's, Jensen's, Martin's medium. Maximum width of conidia was recorded on YPSS medium followed by Sabouraud's medium. The average size of spores on nematode infested corn meal agar medium was slightly increased than those on corn meal agar medium.

Enterococcus in surface waters from the Des Moines River (Iowa) watershed: location, persistence and vancomycin resistance.

PubMed

Larsen, Bryan; Essmann, Michael K; Geletta, Simon; Duff, Barbara

2012-01-01

The object of this study was to quantify vancomycin-resistant enterococci in surface water from Central Iowa obtained from April 2007 to August 2007. Water from established sampling sites in four watersheds was plated on bile-esculin agar. Presumptively identified enterococci were categorized as "above the level of concern" if the sample contained ≥ 107 CFU per 100 ml. Confirmation of isolates as enterococci was based on growth at elevated temperature in high salt and on Enterococcus agar. Isolates that grew on 6 μg/ml vancomycin agar were deemed resistant. PCR analysis of resistant strains characterized vancomycin resistance genes. 77.2% of surface water samples from Central Iowa contained enterococci. Among enterococcal isolates, 10.4% grew on media containing 6 μg/ml vancomycin. PCR analysis of resistance genes showed a preponderance of VanC2/C3 in the area studied and VanB was not detected. Vancomycin-resistant Enterococcus is present in Central Iowa surface waters but resistance rarely involved VanA genotypes. Nevertheless, the potential for community-acquired infections remains a risk.

Reflected scatterometry for noninvasive interrogation of bacterial colonies

NASA Astrophysics Data System (ADS)

Kim, Huisung; Doh, Iyll-Joon; Sturgis, Jennifer; Bhunia, Arun K.; Robinson, J. Paul; Bae, Euiwon

2016-10-01

A phenotyping of bacterial colonies on agar plates using forward-scattering diffraction-pattern analysis provided promising classification of several different bacteria such as Salmonella, Vibrio, Listeria, and E. coli. Since the technique is based on forward-scattering phenomena, light transmittance of both the colony and the medium is critical to ensure quality data. However, numerous microorganisms and their growth media allow only limited light penetration and render the forward-scattering measurement a challenging task. For example, yeast, Lactobacillus, mold, and several soil bacteria form colorful and dense colonies that obstruct most of the incoming light passing through them. Moreover, blood agar, which is widely utilized in the clinical field, completely blocks the incident coherent light source used in forward scatterometry. We present a newly designed reflection scatterometer and validation of the resolving power of the instrument. The reflectance-type instrument can acquire backward elastic scatter patterns for both highly opaque media and colonies and has been tested with three different bacterial genera grown on blood agar plates. Cross-validation results show a classification rate above 90% for four genera.

Airborne Salmonella and Listeria associated with Irish commercial beef, sheep and pig plants.

PubMed

Okraszewska-Lasica, Wioletta; Bolton, D J; Sheridan, J J; McDowell, D A

2014-06-01

Air samples from lairage, hide/fleece pulling or dehairing/scraping, evisceration and chilling areas in commercial beef, sheep and pig plants were examined for Salmonella spp. and Listeria monocytogenes, by impaction or sedimentation onto selective (Brilliant Green Agar, BSA; Listeria Selective Agar, LSA) and non-selective (Plate Count Agar, PCA) media. Both pathogens were frequently detected in all three plants. Improved recoveries were achieved by combining sedimentation, and broth based resuscitation, suggesting cell injury. Salmonella were recovered from all three plants, with the highest counts on BGA in the pig plant. The most common serotypes were S. Typhimurium in the beef/sheep plants and S. Derby in the pig plant. Very low counts of L. monocytogenes (e.g. 2.6CFUm(2)) were detected at hide removal on LSA sedimentation plates in the beef plant. These included serogroup 1/2a-3a and 1/2b-3b-7. Pathogen counts in the three plants were generally very low, suggesting that air is unlikely to be a significant source of carcass or plant surface contamination. Copyright © 2014 Elsevier Ltd. All rights reserved.

Broth versus solid agar culture of swab samples of cadaveric allograft musculoskeletal tissue.

PubMed

Varettas, Kerry

2013-12-01

As part of the donor assessment protocol, bioburden assessment must be performed on allograft musculoskeletal tissue samples collected at the time of tissue retrieval. Swab samples of musculoskeletal tissue allografts from cadaveric donors are received at the microbiology department of the South Eastern Area Laboratory Services (Australia) to determine the presence of bacteria and fungi. This study will review the isolation rate of organisms from solid agar and broth culture of swab samples of cadaveric allograft musculoskeletal tissue over a 6-year period, 2006-2011. Swabs were inoculated onto horse blood agar (anaerobic, 35 °C) and chocolate agar (CO2, 35 °C) and then placed into a cooked meat broth (aerobic, 35 °C). A total of 1,912 swabs from 389 donors were received during the study period. 557 (29.1 %) swabs were culture positive with the isolation of 713 organisms, 249 (34.9 %) from solid agar culture and an additional 464 (65.1 %) from broth culture only. This study has shown that the broth culture of cadaveric allograft musculoskeletal swab samples recovered a greater amount of organisms than solid agar culture. Isolates such as Clostridium species and Staphylococcus aureus would not have been isolated from solid agar culture alone. Broth culture is an essential part of the bioburden assessment protocol of swab samples of cadaveric allograft musculoskeletal tissue in this laboratory.

[GROWTH OF MICROMYCETES FROM DIFFERENT ECOLOGICAL NICHES ON AGAR NUTRIENT MEDIA].

PubMed

Kurchenko, I M; Yurieva, E M; Voychuk, S I

2015-01-01

Radial growth rate of (K(r)) 153 strains 6 species of micromycetes from different ecological niches was studied on 7 agar media: three standard (malt extract agar, potato-dextrose agar, Czapek's agar), and on agar media with plant polymers (carboxymethylcellulose, xylan, soluble starch and apple pectin). Endophytic and plant pathogenic strains (biotrophs) of all studied species did not differ significantly in their ability to grow on nutrient media of different composition--average values of K(r) for these two groups were the same (0,200 and 0,199 mm/h, respectively). Soil micromycetes (saprophytes) characterized by the lowest average growth rate (0,169 mm/h) and significantly differed from the endophytic and plant pathogenic ones. Average of the radial growth rates of studied microscopic fungi were higher on standard nutrient media than with plant polymers ones. Growth parameters of endophytes and plant pathogens of all studied species on various agar media differed from the soil strains. High growth rate of endophytic and plant pathogenic strains of Fusarium poae, Alternaria alternata and Ceratocystis sp. provides them the rapid colonization of plants. Penicillium funiculosum strains equally can exist as saprophytes in soil and as endophytic plant symbionts. A wide range of K(r) variation of endophytic dark pigmented Mycelia sterilia indicates the presence in this group of different species of micromycetes, which have no sporulation.

Hydroxyethyl cellulose hydrogel for wound dressing: Fabrication, characterization and in vitro evaluation.

PubMed

El Fawal, Gomaa F; Abu-Serie, Marwa M; Hassan, Mohamed A; Elnouby, Mohamed S

2018-05-01

In this study, new hydrogel membranes were developed based on hydroxyethyl cellulose (HEC) supplemented with tungsten oxide for further implementing in wound treatment. HEC hydrogel membranes were fabricated and crosslinked using citric acid (CA). Various tests were carried out including FTIR, XRD, porosity measurements, swelling, mechanical properties, gel fraction, and thermal gravimetric analysis to evaluate the efficiency of the prepared membranes as wound dressing material. In addition, wound healing activity of the examined membranes for human dermal fibroblast cell line was investigated employing in vitro scratching model. Furthermore, the potency of the prepared membranes to suppress wound complications was studied via determination of their anti-inflammatory and antibacterial activities exploiting MTT, ELISA, and disk agar diffusion methods. The results demonstrated that the HEC hydrogel membranes revealed an anti-inflammatory and antibacterial efficacy. Moreover, HEC improved the safety of tungsten oxide toward normal human cells (white blood cells and dermal fibroblast). Furthermore, HEC membranes loaded with WO 3 revealed the highest activities against Salmonella sp. pursued by P. aeruginosa in compared with the negative HEC hydrogel membrane. The current approach corroborated that HEC amended by tungsten oxide could be applied as a promising safe candidate for wound dressing material. Copyright © 2018 Elsevier B.V. All rights reserved.

Occurrence and species distribution of pathogenic Mucorales in unselected soil samples from France.

PubMed

Mousavi, B; Costa, J M; Arné, P; Guillot, J; Chermette, R; Botterel, F; Dannaoui, E

2018-04-01

Mucormycosis is a life-threatening invasive fungal disease that affects a variety of patient groups. Although Mucorales are mostly opportunistic pathogens originating from soil or decaying vegetation, there are currently few data on prevalence of this group of fungi in the environment. The aim of the present study was to assess the prevalence and diversity of species of Mucorales from soil samples collected in France. Two grams of soil were homogenized in sterile saline and plated on Sabouraud dextrose agar and RPMI agar supplemented with itraconazole or voriconazole. Both media contained chloramphenicol and gentamicin. The plates were incubated at 35 ± 2 °C and checked daily for fungal growth for a maximum of 7 d. Mucorales were subcultured for purity. Each isolate was identified phenotypically and molecular identification was performed by ITS sequencing. A total of 170 soil samples were analyzed. Forty-one isolates of Mucorales were retrieved from 38 culture-positive samples. Among the recovered isolates, 27 Rhizopus arrhizus, 11 Mucor circinelloides, one Lichtheimia corymbifera, one Rhizopus microsporus and one Cunninghamella bertholletiae were found. Positive soil samples came from cultivated fields but also from other types of soil such as flower beds. Mucorales were retrieved from samples obtained in different geographical regions of France. Voriconazole-containing medium improved the recovery of Mucorales compared with other media. The present study showed that pathogenic Mucorales are frequently recovered from soil samples in France. Species diversity should be further analyzed on a larger number of soil samples from different geographic areas in France and in other countries.

[Periodontal microbiota and microorganisms isolated from heart valves in patients undergoing valve replacement surgery in a clinic in Cali, Colombia].

PubMed

Moreno, Sandra; Parra, Beatriz; Botero, Javier E; Moreno, Freddy; Vásquez, Daniel; Fernández, Hugo; Alba, Sandra; Gallego, Sara; Castillo, Gilberto; Contreras, Adolfo

2017-12-01

Periodontitis is an infectious disease that affects the support tissue of the teeth and it is associated with different systemic diseases, including cardiovascular disease. Microbiological studies facilitate the detection of microorganisms from subgingival and cardiovascular samples. To describe the cultivable periodontal microbiota and the presence of microorganisms in heart valves from patients undergoing valve replacement surgery in a clinic in Cali. We analyzed 30 subgingival and valvular tissue samples by means of two-phase culture medium, supplemented blood agar and trypticase soy agar with antibiotics. Conventional PCR was performed on samples of valve tissue. The periodontal pathogens isolated from periodontal pockets were: Fusobacterium nucleatum (50%), Prevotella intermedia/ nigrescens (40%), Campylobacter rectus (40%), Eikenella corrodens (36.7%), Gram negative enteric bacilli (36.7%), Porphyromonas gingivalis (33.3%), and Eubacterium spp. (33.3%). The pathogens isolated from the aortic valve were Propionibacterium acnes (12%), Gram negative enteric bacilli (8%), Bacteroides merdae (4%), and Clostridium bifermentans (4%), and from the mitral valve we isolated P. acnes and Clostridium beijerinckii. Conventional PCR did not return positive results for oral pathogens and bacterial DNA was detected only in two samples. Periodontal microbiota of patients undergoing surgery for heart valve replacement consisted of species of Gram-negative bacteria that have been associated with infections in extraoral tissues. However, there is no evidence of the presence of periodontal pathogens in valve tissue, because even though there were valve and subgingival samples positive for Gram-negative enteric bacilli, it is not possible to maintain they corresponded to the same phylogenetic origin.

Molecular typing of environmental Cryptococcus neoformans/C. gattii species complex isolates from Manaus, Amazonas, Brazil.

PubMed

Alves, Gleica Soyan Barbosa; Freire, Ana Karla Lima; Bentes, Amaury Dos Santos; Pinheiro, José Felipe de Souza; de Souza, João Vicente Braga; Wanke, Bodo; Matsuura, Takeshi; Jackisch-Matsuura, Ani Beatriz

2016-08-01

Cryptococcus neoformans and Cryptococcus gattii are the main causative agents of cryptococcosis, a systemic fungal disease that affects internal organs and skin, and which is acquired by inhalation of spores or encapsulated yeasts. It is currently known that the C. neoformans/C. gattii species complex has a worldwide distribution, however, some molecular types seem to prevail in certain regions. Few environmental studies of Cryptococcus have been conducted in the Brazilian Amazon. This is the first ecological study of the pathogenic fungi C. neoformans/C. gattii species complex in the urban area of Manaus, Amazonas, Brazil. A total of 506 samples from pigeon droppings (n = 191), captive bird droppings (n = 60) and tree hollows (n = 255) were collected from June 2012 to January 2014 at schools and public buildings, squares, pet shops, households, the zoo and the bus station. Samples were plated on niger seed agar (NSA) medium supplemented with chloramphenicol and incubated at 25°C for 5 days. Dark-brown colonies were isolated and tested for thermotolerance at 37°C, cycloheximide resistance and growth on canavanine-glycine-bromothymol blue agar. Molecular typing was done by PCR-RFLP. Susceptibility to the antifungal drugs amphotericin B, fluconazole, itraconazole and ketoconazole was tested using Etest(®) strips. In total, 13 positive samples were obtained: one tree hollow (C. gattiiVGII), nine pigeon droppings (C. neoformansVNI) and three captive bird droppings (C. neoformansVNI). The environmental cryptococcal isolates found in this study were of the same molecular types as those responsible for infections in Manaus. © 2016 Blackwell Verlag GmbH.

Antibiotic susceptibility of periodontal Streptococcus constellatus and Streptococcus intermedius clinical isolates.

PubMed

Rams, Thomas E; Feik, Diane; Mortensen, Joel E; Degener, John E; van Winkelhoff, Arie J

2014-12-01

Streptococcus constellatus and Streptococcus intermedius in subgingival dental plaque biofilms may contribute to forms of periodontitis that resist treatment with conventional mechanical root debridement/surgical procedures and may additionally participate in some extraoral infections. Because systemic antibiotics are often used in these clinical situations, and little is known of the antibiotic susceptibility of subgingival isolates of these two bacterial species, this study determined the in vitro susceptibility to six antibiotics of fresh S. constellatus and S. intermedius clinical isolates from human periodontitis lesions. A total of 33 S. constellatus and 17 S. intermedius subgingival strains, each recovered from separate patients with severe chronic periodontitis (n = 50) before treatment, were subjected to antibiotic gradient strip susceptibility testing with amoxicillin, azithromycin, clindamycin, ciprofloxacin, and doxycycline on blood-supplemented Mueller-Hinton agar and to the inhibitory effects of metronidazole at 16 mg/L in an enriched Brucella blood agar dilution assay. Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing interpretative standards were used to assess the results. Clindamycin was the most active antibiotic against S. constellatus (minimum inhibitory concentration at 90% [MIC90] 0.25 mg/L), and amoxicillin was most active against S. intermedius (MIC90 0.125 mg/L). A total of 30% of the S. constellatus and S. intermedius clinical isolates were resistant in vitro to doxycycline, 98% were only intermediate in susceptibility to ciprofloxacin, and 90% were resistant to metronidazole at 16 mg/L. Subgingival S. constellatus and S. intermedius exhibited variable antibiotic susceptibility profiles, potentially complicating empirical selection of periodontitis antibiotic therapy in patients who are species positive.

Bacillus Classification Based on Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry-Effects of Culture Conditions.

PubMed

Shu, Lin-Jie; Yang, Yu-Liang

2017-11-14

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a reliable and rapid technique applied widely in the identification and classification of microbes. MALDI-TOF MS has been used to identify many endospore-forming Bacillus species; however, endospores affect the identification accuracy when using MALDI-TOF MS because they change the protein composition of samples. Since culture conditions directly influence endospore formation and Bacillus growth, in this study we clarified how culture conditions influence the classification of Bacillus species by using MALDI-TOF MS. We analyzed members of the Bacillus subtilis group and Bacillus cereus group using different incubation periods, temperatures and media. Incubation period was found to affect mass spectra due to endospores which were observed mixing with vegetative cells after 24 hours. Culture temperature also resulted in different mass spectra profiles depending on the temperature best suited growth and sporulation. Conversely, the four common media for Bacillus incubation, Luria-Bertani agar, nutrient agar, plate count agar and brain-heart infusion agar did not result in any significant differences in mass spectra profiles. Profiles in the range m/z 1000-3000 were found to provide additional data to the standard ribosomal peptide/protein region m/z 3000-15000 profiles to enable easier differentiation of some highly similar species and the identification of new strains under fresh culture conditions. In summary, control of culture conditions is vital for Bacillus identification and classification by MALDI-TOF MS.

An Agar-Based Method for Plating Marine Protozoan Parasites of the Genus Perkinsus

PubMed Central

Cold, Emma R.; Freyria, Nastasia J.; Martínez Martínez, Joaquín; Fernández Robledo, José A.

2016-01-01

The genus Perkinsus includes protozoan parasites of mollusks responsible for losses in the aquaculture industry and hampering the recovery of natural shellfish beds worldwide, and they are a key taxon for understanding intracellular parasitism adaptations. The ability to propagate the parasite in liquid media, in the absence of the host, has been crucial for improving understanding of its biology; however, alternative techniques to grow the parasite are needed to explore other basic aspects of the Perkinsus spp. biology. We optimized a DME: Ham’s F12–5% FBS- containing solid agar medium for plating Perkinsus marinus. This solid medium supported trophozoite propagation both by binary fission and schizogony. Colonies were visible to the naked eye 17 days after plating. We tested the suitability of this method for several applications, including the following: 1) Subcloning P. marinus isolates: single discrete P. marinus colonies were obtained from DME: Ham’s F12–5% FBS– 0.75% agar plates, which could be further propagated in liquid medium; 2) Subcloning engineered Perkinsus mediterraneus MOE[MOE]: GFP by streaking cultures on plates; 3) Chemical susceptibility: Infusing the DME: Ham’s F12–5% FBS– 0.75% agar plates with triclosan resulted in inhibition of the parasite propagation in a dose-dependent manner. Altogether, our plating method has the potential for becoming a key tool for investigating diverse aspects of Perkinsus spp. biology, developing new molecular tools, and for biotechnological applications. PMID:27149378

Selection of Brain Metastasis-Initiating Breast Cancer Cells Determined by Growth on Hard Agar

PubMed Central

Guo, Lixia; Fan, Dominic; Zhang, Fahao; Price, Janet E.; Lee, Ju-Seog; Marchetti, Dario; Fidler, Isaiah J.; Langley, Robert R.

2011-01-01

An approach that facilitates rapid isolation and characterization of tumor cells with enhanced metastatic potential is highly desirable. Here, we demonstrate that plating GI-101A human breast cancer cells on hard (0.9%) agar selects for the subpopulation of metastasis-initiating cells. The agar-selected cells, designated GI-AGR, were homogeneous for CD44+ and CD133+ and five times more invasive than the parental GI-101A cells. Moreover, mice injected with GI-AGR cells had significantly more experimental brain metastases and shorter overall survival than did mice injected with GI-101A cells. Comparative gene expression analysis revealed that GI-AGR cells were markedly distinct from the parental cells but shared an overlapping pattern of gene expression with the GI-101A subline GI-BRN, which was generated by repeated in vivo recycling of GI-101A cells in an experimental brain metastasis model. Data mining on 216 genes shared between GI-AGR and GI-BRN breast cancer cells suggested that the molecular phenotype of these cells is consistent with that of cancer stem cells and the aggressive basal subtype of breast cancer. Collectively, these results demonstrate that analysis of cell growth in a hard agar assay is a powerful tool for selecting metastasis-initiating cells in a heterogeneous population of breast cancer cells, and that such selected cells have properties similar to those of tumor cells that are selected based on their potential to form metastases in mice. PMID:21514446

Optimisation of a direct plating method for the detection and enumeration of Alicyclobacillus acidoterrestris spores.

PubMed

Henczka, Marek; Djas, Małgorzata; Filipek, Katarzyna

2013-01-01

A direct plating method for the detection and enumeration of Alicyclobacillus acidoterrestris spores has been optimised. The results of the application of four types of growth media (BAT agar, YSG agar, K agar and SK agar) regarding the recovery and enumeration of A. acidoterrestris spores were compared. The influence of the type of applied growth medium, heat shock conditions, incubation temperature, incubation time, plating technique and the presence of apple juice in the sample on the accuracy of the detection and enumeration of A. acidoterrestris spores was investigated. Among the investigated media, YSG agar was the most sensitive medium, and its application resulted in the highest recovery of A. acidoterrestris spores, while K agar and BAT agar were the least suitable media. The effect of the heat shock time on the recovery of spores was negligible. When there was a low concentration of spores in a sample, the membrane filtration method was superior to the spread plating method. The obtained results show that heat shock carried out at 80°C for 10 min and plating samples in combination with membrane filtration on YSG agar, followed by incubation at 46°C for 3 days provided the optimal conditions for the detection and enumeration of A. acidoterrestris spores. Application of the presented method allows highly efficient, fast and sensitive identification and enumeration of A. acidoterrestris spores in food products. This methodology will be useful for the fruit juice industry for identifying products contaminated with A. acidoterrestris spores, and its practical application may prevent economic losses for manufacturers. Copyright © 2012 Elsevier B.V. All rights reserved.

Enhancement of catalytic, reusability, and long-term stability features of Trametes versicolor IBL-04 laccase immobilized on different polymers.

PubMed

Asgher, Muhammad; Noreen, Sadia; Bilal, Muhammad

2017-02-01

In the current study, different bio-polymers such as agar-agar, polyacrylamide and gelatin were utilized as bolster materials for the immobilization of a fungal laccase through entrapment approach. Among the polymers, agar-agar matrix most firmly encapsulated the enzyme yielding significant laccase immobilization (79.65±2.55%). Immobilization prolonged the reaction time of laccase and agar-agar, polyacrylamide and gelatin entrapped laccases displayed maximum catalytic activities after 10.0, 15.0 and 10.0min of reaction, respectively, as compared to free counterpart (5.0min). It also increased the optimal temperature by 5.0-10°C and provided an alkaline shift of the pH optima to agar-agar and gelatin entrapped laccase, while, in case of polyacrylamide, optimum pH was displaced to acidic region. Kinetic data revealed that K m(app) values were slightly increased while V max values were decreased as compared to free counterpart. Polymers encapsulation led to significant improvement in activity against thermal denaturation. After 180min at 60°C, the enzymes preserved 28.1±0.9, 48.6±1.3 and 32.5±1.8% residual activities, respectively, whereas, the free enzyme was completely inactive. Immobilization enabled the enzymes to resist a number of different effectors including metal ions, inhibitors/denaturants and chelating agents. Moreover, the resulted modified laccases displayed good recycling capability for substrate-oxidation reactions in several successive batches. In summary, the tremendously improved attributes of polymers-encapsulated enzymes display a high potential for various applications in different industrial sectors. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of the Granada agar plate for detection of vaginal and rectal group B streptococci in pregnant women.

PubMed

Gil, E G; Rodríguez, M C; Bartolomé, R; Berjano, B; Cabero, L; Andreu, A

1999-08-01

Granada medium was evaluated for the detection of group B streptococci (GBS) in vaginal and rectal swabs compared with selective Columbia blood agar and selective Lim broth. From May 1996 to March 1998, 702 pregnant women (35 to 37 weeks of gestation) participated in this three-phase study; 103 (14.7%) of these women carried GBS. In the first phase of the experiment (n = 273 women), vaginorectal specimens were collected on the same swab; the sensitivities of Granada tube, selective Columbia blood agar, and Lim broth were 31.4, 94.3, and 74.3%, respectively. In the second and third phases (n = 429 women), vaginal and rectal specimens were collected separately; the sensitivities of Granada plate, selective Columbia blood agar, and Lim broth (subcultured at 4 h on selective Columbia agar in the second phase and at 18 to 24 h in Granada plate in the third phase) were 91.1, 83.9, and 75%, respectively, in the second phase and 88.5, 90.4, and 63.5%, respectively, in the third phase. There were no statistically significant differences in GBS recovery between the Granada agar plate and selective Columbia blood agar, but the Granada plate provided a clear advantage; the characteristic red-orange colonies produced overnight by GBS can be identified by the naked eye and is so specific that further identification is unnecessary. The use of the Granada tube and Lim broth did not result in increased isolation of GBS. In conclusion, the Granada agar plate is highly sensitive for detecting GBS in vaginal and rectal swabs from pregnant women and can provide results in 18 to 24 h.

Roughness-controlled self-assembly of mannitol/LB agar microparticles by polymorphic transformation for pulmonary drug delivery.

PubMed

Zhang, Fengying; Ngoc, Nguyen Thi Quynh; Tay, Bao Hui; Mendyk, Aleksander; Shao, Yu-Hsuan; Lau, Raymond

2015-01-05

Novel roughness-controlled mannitol/LB Agar microparticles were synthesized by polymorphic transformation and self-assembly method using hexane as the polymorphic transformation reagent and spray-dried mannitol/LB Agar microparticles as the starting material. As-prepared microparticles were characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction spectra (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and Andersen Cascade Impactor (ACI). The XRD and DSC results indicate that after immersing spray-dried mannitol/LB Agar microparticles in hexane, β-mannitol was completely transformed to α-mannitol in 1 h, and all the δ-mannitol was transformed to α form after 14 days. SEM shows that during the transformation the nanobelts on the spray-dried mannitol/LB Agar microparticles become more dispersed and the contour of the individual nanobelts becomes more noticeable. Afterward, the nanobelts self-assemble to nanorods and result in rod-covered mannitol/LB Agar microparticles. FTIR indicates new hydrogen bonds were formed among mannitol, LB Agar, and hexane. SEM images coupled with image analysis software reveal that different surface morphology of the microparticles have different drug adhesion mechanisms. Comparison of ACI results and image analysis of SEM images shows that an increase in the particle surface roughness can increase the fine particle fractions (FPFs) using the rod-covered mannitol microparticles as drug carriers. Transformed microparticles show higher FPFs than commercially available lactose carriers. An FPF of 28.6 ± 2.4% was achieved by microparticles transformed from spray-dried microparticles using 2% mannitol(w/v)/LB Agar as feed solution. It is comparable to the highest FPF reported in the literature using lactose and spray-dried mannitol as carriers.

Phacidiopycnis washingtonensis--a new species associated with pome fruits from Washington State.

PubMed

Xiao, C L; Rogers, J D; Kim, Y K; Liu, Q

2005-01-01

A new species of Phacidiopycnis associated with pome fruits is described. The fungus causes fruit rot on apples during storage and is associated with a twig dieback and canker disease of crabapple trees and dead twigs of pear trees. To characterize the biology of the fungus and compare it with Ph. piri, the type species of the genus, effects of nine media and light on mycelial growth and pycnidial production, mycelial growth in response to temperature and mode of conidial germination in response to nutrient were determined. Apple-juice agar, pear-juice agar, prune-juice agar, potato-dextrose agar (PDA) and malt-extract agar, Czapek-Dox agar and oatmeal agar (OMA) favored mycelial growth. Cornmeal agar (CMA) did not favor mycelial growth. Light effect on pycnidial formation was medium dependent. Abundant pycnidia with mature conidia formed in 14 d old PDA and OMA cultures at 20 C, regardless of light, whereas none or very few pycnidia formed on other media in the dark. Fluorescent light stimulated formation of pycnidia except on CMA. The fungus grew at -3-25 C, with optimum growth at 15-20 C. Conidia germinated either by forming germ tubes or less often by budding. Budding of conidia occurred in 1 and 10% pear-juice solutions but not in 100% pear-juice solution. Six isolates of Ph. washingtonensis from different species of pome fruits had identical ITS sequences. The sizes of the ITS region were the same for both Ph. washingtonensis and Ph. piri, and four polymorphic nucleotide sites were found in the ITS region between Ph. washingtonensis and Ph. piri. The similarity in ITS sequences between these two taxa is confirmatory evidence for the erection of the new species of Phacidiopycnis associated with pome fruits we describe here.

Performance of CHROMAGAR candida and BIGGY agar for identification of yeast species.

PubMed

Yücesoy, Mine; Marol, Serhat

2003-10-29

The importance of identifying the pathogenic fungi rapidly has encouraged the development of differential media for the presumptive identification of yeasts. In this study two differential media, CHROMagar Candida and bismuth sulphite glucose glycine yeast agar, were evaluated for the presumptive identification of yeast species. A total number of 270 yeast strains including 169 Candida albicans, 33 C. tropicalis, 24 C. glabrata, 18 C. parapsilosis, 12 C. krusei, 5 Trichosporon spp., 4 C. kefyr, 2 C. lusitaniae, 1 Saccharomyces cerevisiae and 1 Geotrichum candidum were included. The strains were first identified by germ tube test, morphological characteristics on cornmeal tween 80 agar and Vitek 32 and API 20 C AUX systems. In parallel, they were also streaked onto CHROMagar Candida and bismuth sulphite glucose glycine yeast agar plates. The results were read according to the color, morphology of the colonies and the existance of halo around them after 48 hours of incubation at 37 degrees C. The sensitivity and specificity values for C. albicans strains were found to be 99.4, 100% for CHROMagar Candida and 87.0, 75.2% for BiGGY agar, respectively. The sensitivity of CHROMagar Candida to identify C. tropicalis, C. glabrata and C. krusei ranged between 90.9 and 100% while the specificity was 100%. The sensitivity rates for BiGGY agar were 66.6 and 100% while the specificity values were found to be 95.4 and 100% for C. tropicalis and C. krusei, respectively. It can be concluded that the use of CHROMagar Candida is an easy and reliable method for the presumptive identification of most commonly isolated Candida species especially C. albicans, C. tropicalis and C. krusei. The lower sensitivity and specificity of BiGGY agar to identify commonly isolated Candida species potentially limits the clinical usefulness of this agar.

Study of methods for the improvement of bacterial transport media

NASA Technical Reports Server (NTRS)

Gardner, R. L.; Beakley, J. W.

1973-01-01

A series of 500 transport media recipes was tested for ability to hold pure cultures of Streptococcus equisimilus, Corynebacterium equi, Neisseria perflava, and Haemophilus parainfluenzae for 21 days. Stuart Medium Base with 0.4% agar was used as the control medium for this and the other experiments in the investigation. At the end of the holding period inoculated transport media were quantitatively assayed, and the control media were assayed immediately after inoculation. Three vials of each medium were inoculated with an organism, and each vial's medium was diluted and spread on duplicate plates. Assay media for this experiment included Brain Heart Infusion,(BHIA) Tryptic Soy Agar, and BHIA with 1% Isovitalex enrichment.

Effects of physical factors on the swarming motility of text itPseudomonas aeruginosa

NASA Astrophysics Data System (ADS)

Si, Tieyan; Ma, Zidong; Tang, Wai Shing; Yang, Alexander; Tang, Jay

Many species of bacteria can spread over a semi-solid surface via a particular form of collective motion known as surface swarming. Using Pseudomonas aeruginosa as a model organism, we investigate physical factors that either facilitate or restrict the swarming motility. The semi-solid surface is typically formed by 0.5-1% agar containing essential nutrients for the bacterial growth and proliferation. Most bacterial species, including P. aeruginosa, synthesize bio-surfactants to aid in swarming. We found addition of exogenous surfactants such as triton into the agar matrix enhances the swarming. In contrast, increasing agar percentage, infusing osmolites, and adding viscous agents all decrease swarming. We propose that the swarming speed is restricted by the rate of water supply from within the agar gel and by the line tension at the swarm front involving three materials in contact: the air, the bacteria propelled liquid film, and the agar substrate.

Evaluating the Risk of Tumors Diseases Based on Measurement of Urinary and Serumal Antioxidants Using the New Agar Diffusion Methods

PubMed Central

Zhou, Ying; Chen, Jing; Wang, Zhen

2017-01-01

Objectives. To discuss the characteristics of the amount of urinary total antioxidants in tumor diseases and the possibility of utilizing the changing regulation of urinary antioxidants to diagnose tumor diseases. Method. Urine and serum specimens from 130 healthy people were used to investigate the variation of antioxidant capacity against age. Urine and serum specimens from 44 unselected patients with tumors and 44 healthy people with same age background were used to explore the significance of urinary antioxidant capacity in clinic to diagnose tumor diseases. Potassium permanganate agar method and iodine starch method were used to determine the amount of total antioxidants. Results. In healthy people, more antioxidants in urine were measured in older people, while the results were opposite in serum. More antioxidants were found in urine of tumor patients than in healthy people with same age-range. Conclusions. According to the results of 130 measurements, the amount of antioxidants in urine varies by age. By using agar methods to measure antioxidants, the effect of age is required to be considered. Antioxidants levels from tumor patients were significantly higher than healthy individuals in urine. The combination of urine and serum to determine total antioxidants can better diagnose tumor diseases based on iodine starch method, with area under the receiver operating characteristics curve at 0.787. PMID:28458777

Oral microbiota, dental caries and periodontal status in smokeless tobacco chewers in Karnataka, India: a case-control study.

PubMed

Nagarajappa, Sandesh; Prasad, Kakarla V V

2010-01-01

The aim of the present study was to compare dental caries and periodontal disease status associated with oral microflora among smokeless tobacco chewers and non-chewers. Forty-two smokeless tobacco chewers and 42 non-chewers (age 20 to 60 years) were assessed for dental caries and periodontal disease status using the Decayed Missing Filled Surface (DMFS) Index, Community Periodontal Index (CPI) and Loss of Attachment (LA) Index. Stimulated saliva and subgingival plaque samples were collected from each subject for performing a culture-based analysis of 20 types of oral microorganisms. Qualitative and semi-quantitative culture-based analysis using MacConkey agar, and aerobic and anaerobic blood agar was carried out to determine the total cultivable microflora. Mutans-Sanguis agar, Pfizer selective Enterococcus agar and Rogosa SL agar were used for the culture of microorganisms associated with dental caries. Mann–Whitney U test and Student t test were employed to compare colony-forming units (CFUs) and caries experience between smokeless tobacco chewers and nonchewers. Z proportionality test was used to compare the periodontal disease status. Caries experience among chewers (26 of 42), that is those subjects who were affected by caries, was significantly less at 61.9% (mean DMFS = 3.5) compared to non-chewers (38 of 42, 90.5%) (mean DMFS = 5.5) (P < 0.05). Deep pockets measuring > 5.5 mm on a CPI probe were found among 26.2% of chewers and 19.1% of nonchewers, with no statistically significant differences (P > 0.05). Counts of Lactobacillus species were significantly lower among chewers (median CFU = 0.788 x 10⁵) than among non-chewers (median CFU = 1.52 x 10⁵) (P < 0.05). Prevotella and Porphyromonas species had a median CFU of 0.04 x 105 in chewers and 0.15 x 10⁵ in non-chewers, whereas Fusobacterium species had a median CFU of 0.02 x 10⁵ in chewers and 0.1 x 10⁵ in non-chewers (P < 0.05). A higher percentage of caries among non-chewers can be explained by greater numbers of Lactobacillus species in this population. Chewers experienced a slightly higher incidence of periodontal disease than non-chewers, but the difference was not significant. These clinical observations suggest a lower ability of Gram-negative bacteria to mediate more periodontal disease in this population.

Use of agar diffusion assay to evaluate bactericidal activity of formulations of alkaline salts of fatty acids against bacteria associated with poultry processing

USDA-ARS?s Scientific Manuscript database

The agar diffusion assay was used to examine antibacterial activity of alkaline salts of fatty acids (FA). Wells in agar media seeded with bacteria were filled with FA-potassium hydroxide (KOH) solutions, plates were incubated, and zones of inhibition were measured. The relationship between bacteric...

Differentiating non-0157:H7 STEC serogroups from ground beef plated on agar media by hyperspetral imaging

USDA-ARS?s Scientific Manuscript database

Introduction: The development of an assay to detect and confirm a positive non-O157:H7 isolate is challenging when mixed morphologically results are obtained from the serogroups growing on Rainbow agar. Rainbow agar is only claimed by the manufacturer to be very specific for E.coli O157:H7 strain...

Growth characteristics of Bacillus anthracis compared to other Bacillus spp. on the selective nutrient media Anthrax Blood Agar and Cereus Ident Agar.

PubMed

Tomaso, Herbert; Bartling, Carsten; Al Dahouk, Sascha; Hagen, Ralf M; Scholz, Holger C; Beyer, Wolfgang; Neubauer, Heinrich

2006-01-01

Anthrax Blood Agar (ABA) and Cereus Ident Agar (CEI) were evaluated as selective growth media for the isolation of Bacillus anthracis using 92 B. anthracis and 132 other Bacillus strains from 30 species. The positive predictive values for the identification of B. anthracis on ABA, CEI, and the combination of both were 72%, 71%, and 90%, respectively. Thus, less than 10% of all species were misidentified using both nutrient media. Species which might be misidentified as B. anthracis were B. cereus, B. mycoides, and B. thuringiensis. Particularly, 30% of B. weihenstephanensis strains were misidentified as B. anthracis.

Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

PubMed

Soto-Reyes, Nohemí; Temis-Pérez, Ana L; López-Malo, Aurelio; Rojas-Laguna, Roberto; Sosa-Morales, María Elena

2015-05-01

Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes. © 2015 Institute of Food Technologists®

[Screening and identification of a bacterium capable of converting agar to neoagaro oligosaccharides].

PubMed

Han, Junping; Huang, Yayan; Ye, Jing; Xiao, Meitian

2015-09-04

To screen and identify a bacterium capable of converting agar to neoagaro oligosaccharides. We took samples of porphyra haitanensis and nearby seawater, and then used the medium containing 1 per thousand agar to enrich the target bacteria. The target isolates were obtained by dilution-plate method, of which crude enzymes were further obtained by liquid culture. We adopted DNS method to determine the target bacteria which can convert agar to neoagaro oligosaccharides. The phylogenetics was identified by analyzing 16S rDNA sequence and combining the strain's morphological and bacterial colonial physiological biochemical characteristics. We isolated a gram-negative bacterial strain HJPHYXJ-1 capable of transforming agar to neoagaro oligosaccharides. Basic Local Alignment Search Tool (BLAST) search of HJPHYXJ-1's 16S rDNA sequence on GenBank suggested that the similarity between this strain and Vibrio natriegens reached 99% . In addition, the morphological and physiological biochemical characteristics of HJPHYXJ-1 also showed highly similarity to Vibrio natriegens. So we identified HJPHYXJ-1 as Vibrio natriegens. The results of HPLC suggested that the metabolite of enzymatic degradation was neoagaro oligosaccharides. HJPHYXJ-1 or the new isolate of Vibrio natriegens was capable of converting agar to neoagaro oligosaccharides.

Abilities of the mCP Agar Method and CRENAME Alpha Toxin-Specific Real-Time PCR Assay To Detect Clostridium perfringens Spores in Drinking Water

PubMed Central

Maheux, Andrée F.; Bérubé, Ève; Boudreau, Dominique K.; Villéger, Romain; Cantin, Philippe; Boissinot, Maurice; Bissonnette, Luc

2013-01-01

We first determined the analytical specificity and ubiquity (i.e., the ability to detect all or most strains) of a Clostridium perfringens-specific real-time PCR (rtPCR) assay based on the cpa gene (cpa rtPCR) by using a bacterial strain panel composed of C. perfringens and non-C. perfringens Clostridium strains. All non-C. perfringens Clostridium strains tested negative, whereas all C. perfringens strains tested positive with the cpa rtPCR, for an analytical specificity and ubiquity of 100%. The cpa rtPCR assay was then used to confirm the identity of 116 putative C. perfringens isolates recovered after filtration of water samples and culture on mCP agar. Colonies presenting discordant results between the phenotype on mCP agar and cpa rtPCR were identified by sequencing the 16S rRNA and cpa genes. Four mCP−/rtPCR+ colonies were identified as C. perfringens, whereas 3 mCP+/rtPCR− colonies were identified as non-C. perfringens. The cpa rtPCR was negative with all 51 non-C. perfringens strains and positive with 64 of 65 C. perfringens strains. Finally, we compared mCP agar and a CRENAME (concentration and recovery of microbial particles, extraction of nucleic acids, and molecular enrichment) procedure plus cpa rtPCR (CRENAME + cpa rtPCR) for their abilities to detect C. perfringens spores in drinking water. CRENAME + cpa rtPCR detected as few as one C. perfringens CFU per 100 ml of drinking water sample in less than 5 h, whereas mCP agar took at least 25 h to deliver results. CRENAME + cpa rtPCR also allows the simultaneous and sensitive detection of Escherichia coli and C. perfringens from the same potable water sample. In itself, it could be used to assess the public health risk posed by drinking water potentially contaminated with pathogens more resistant to disinfection. PMID:24077714

Development and validation of a large, modular test meal with liquid and solid components for assessment of gastric motor and sensory function by non-invasive imaging.

PubMed

Parker, H L; Tucker, E; Hoad, C L; Pal, A; Costigan, C; Hudders, N; Perkins, A; Blackshaw, E; Gowland, P; Marciani, L; Fox, M R

2016-04-01

Current investigations of stomach function are based on small test meals that do not reliably induce symptoms and analysis techniques that rarely detect clinically relevant dysfunction. This study introduces the large 'Nottingham Test Meal' (NTM) for assessment of gastric motor and sensory function by non-invasive imaging. NTM comprises 400 mL liquid nutrient (0.75 kcal/mL) and 12 solid agar-beads (0 kcal) with known breaking strength. Gastric fullness and dyspeptic sensations were documented by 100 mm visual analogue scale (VAS). Gastric emptying (GE) were measured in 24 healthy volunteers (HVs) by gastric scintigraphy (GS) and magnetic resonance imaging (MRI). The contribution of secretion to gastric volume was assessed. Parameters that describe GE were calculated from validated models. Inter-observer agreement and reproducibility were assessed. NTM produced moderate fullness (VAS ≥30) but no more than mild dyspeptic symptoms (VAS <30) in 24 HVs. Stable binding of meal components to labels in gastric conditions was confirmed. Distinct early and late-phase GE were detected by both modalities. Liquid GE half-time was median 49 (95% CI: 36-62) min and 68 (57-71) min for GS and MRI, respectively. Differences between GS and MRI measurements were explained by the contribution of gastric secretion. Breaking strength for agar-beads was 0.8 N/m(2) such that median 25 (8-50) % intact agar-beads and 65 (47-74) % solid material remained at 120 min on MRI and GS, respectively. Good reproducibility for liquid GE parameters was present and GE was not altered by agar-beads. The NTM provided an objective assessment of gastric motor and sensory function. The results were reproducible and liquid emptying was not affected by non-nutrient agar-beads. The method is potentially suitable for clinical practice. © 2016 John Wiley & Sons Ltd.

The Efficiency of UVC Radiation in the Inactivation of
Listeria monocytogenes on Beef-Agar Food Models.

PubMed

Hamidi-Oskouei, Amir M; James, Christian; James, Stephen

2015-06-01

The aim of this study is to evaluate the effect of meat content and surface smoothness on the deactivation of Listeria monocytogenes in beef-agar food models achieved by shortwave ultraviolet (UVC) light. Food models with various meat contents were made using chopped beef slices and agar solution. Prepared models together with a Listeria selective agar (LSA) plate and a slice of cooked beef were inoculated with L. monocytogenes and then exposed to UVC light. Population of Listeria reduced to below the level of detection on the LSA plates. As the content of beef in the beef-agar models increased, more L. monocytogenes cells survived. Survival was greatest on the treated cooked slice of beef. To better understand the effect of surface irregularities, a white light interferometer was used to analyse the surface smoothness of beef-agar media and LSA plates. No correlation was observed between the surface roughness of seven out of nine types of produced beef-agar media and the degree of inactivation resulting from UVC radiation at the given dose, whereas, less bacterial cells were killed as beef content of the food models increased. The findings of the current study show that the chemical composition of the treated sample also plays an important role in pathogen resistance and survival, meaning that two samples with similar surface irregularities but different chemical composition might produce very different inactivation results when exposed to UVC light.

Performance of chromogenic media for Candida in rapid presumptive identification of Candida species from clinical materials

PubMed Central

Pravin Charles, M. V.; Kali, Arunava; Joseph, Noyal Mariya

2015-01-01

Background: In perspective of the worldwide increase in a number of immunocompromised patients, the need for identification of Candida species has become a major concern. The development of chromogenic differential media, introduced recently, facilitate rapid speciation. However, it can be employed for routine mycology workup only after an exhaustive evaluation of its benefit and cost effectiveness. This study was undertaken to evaluate the benefit and cost effectiveness of chromogenic media for speciation of Candida clinical isolates. Materials and Methods: Sputum samples of 382 patients were screened for the presence of Candida spp. by Gram stain and culture on sabouraud dextrose agar. Candida species were identified using Gram stain morphology, germ tube formation, cornmeal agar with Tween-80, sugar fermentation tests and morphology on HiCrome Candida differential agar. All the Candida isolates were inoculated on HiCrome Candida agar (HiMedia, Mumbai, India). Results: The sensitivity and specificity of HiCrome agar for identification of Candida albicans were 90% and 96.42%, respectively whereas sensitivity and specificity of carbohydrate fermentation test were 86.67% and 74.07%, respectively. Sensitivity and specificity values of HiCrome agar for detection of C. albicans, Candida parapsilosis and Candida glabrata were above 90%. Conclusions: We found HiCrome agar has high sensitivity and specificity comparable to that of the conventional method. In addition, use of this differential media could significantly cut down the turnaround time as well as cost of sample processing. PMID:26109791

Performance of chromogenic media for Candida in rapid presumptive identification of Candida species from clinical materials.

PubMed

Pravin Charles, M V; Kali, Arunava; Joseph, Noyal Mariya

2015-06-01

In perspective of the worldwide increase in a number of immunocompromised patients, the need for identification of Candida species has become a major concern. The development of chromogenic differential media, introduced recently, facilitate rapid speciation. However, it can be employed for routine mycology workup only after an exhaustive evaluation of its benefit and cost effectiveness. This study was undertaken to evaluate the benefit and cost effectiveness of chromogenic media for speciation of Candida clinical isolates. Sputum samples of 382 patients were screened for the presence of Candida spp. by Gram stain and culture on sabouraud dextrose agar. Candida species were identified using Gram stain morphology, germ tube formation, cornmeal agar with Tween-80, sugar fermentation tests and morphology on HiCrome Candida differential agar. All the Candida isolates were inoculated on HiCrome Candida agar (HiMedia, Mumbai, India). The sensitivity and specificity of HiCrome agar for identification of Candida albicans were 90% and 96.42%, respectively whereas sensitivity and specificity of carbohydrate fermentation test were 86.67% and 74.07%, respectively. Sensitivity and specificity values of HiCrome agar for detection of C. albicans, Candida parapsilosis and Candida glabrata were above 90%. We found HiCrome agar has high sensitivity and specificity comparable to that of the conventional method. In addition, use of this differential media could significantly cut down the turnaround time as well as cost of sample processing.

The Efficiency of UVC Radiation in the Inactivation of
Listeria monocytogenes on Beef-Agar Food Models

PubMed Central

James, Christian; James, Stephen

2015-01-01

Summary The aim of this study is to evaluate the effect of meat content and surface smoothness on the deactivation of Listeria monocytogenes in beef-agar food models achieved by shortwave ultraviolet (UVC) light. Food models with various meat contents were made using chopped beef slices and agar solution. Prepared models together with a Listeria selective agar (LSA) plate and a slice of cooked beef were inoculated with L. monocytogenes and then exposed to UVC light. Population of Listeria reduced to below the level of detection on the LSA plates. As the content of beef in the beef-agar models increased, more L. monocytogenes cells survived. Survival was greatest on the treated cooked slice of beef. To better understand the effect of surface irregularities, a white light interferometer was used to analyse the surface smoothness of beef-agar media and LSA plates. No correlation was observed between the surface roughness of seven out of nine types of produced beef-agar media and the degree of inactivation resulting from UVC radiation at the given dose, whereas, less bacterial cells were killed as beef content of the food models increased. The findings of the current study show that the chemical composition of the treated sample also plays an important role in pathogen resistance and survival, meaning that two samples with similar surface irregularities but different chemical composition might produce very different inactivation results when exposed to UVC light. PMID:27904353

Spray method for recovery of heat-injured Salmonella Typhimurium and Listeria monocytogenes.

PubMed

Back, Kyeong-Hwan; Kim, Sang-Oh; Park, Ki-Hwan; Chung, Myung-Sub; Kang, Dong-Hyun

2012-10-01

Selective agar is inadequate for supporting recovery of injured cells. During risk assessment of certain foods, both injured and noninjured cells must be enumerated. In this study, a new method (agar spray method) for recovering sublethally heat-injured microorganisms was developed and used for recovery of heat-injured Salmonella Typhimurium and Listeria monocytogenes. Molten selective agar was applied as an overlay to presolidified nonselective tryptic soy agar (TSA) by spray application. Heat-injured cells (55°C for 10 min in 0.1% peptone water or 55°C for 15 min in sterilized skim milk) were inoculated directly onto solidified TSA. After a 2-h incubation period for cell repair, selective agar was applied to the TSA surface with a sprayer, and the plates were incubated. The recovery rate for heat-injured Salmonella Typhimurium and L. monocytogenes with the spray method was compared with the corresponding rates associated with TSA alone, selective media alone, and the conventional overlay method (selective agar poured on top of resuscitated cells grown on TSA and incubated for 2 h). No significant differences (P > 0.05) were found in pathogen recovery obtained with TSA, the overlay method, and the spray method. However, a lower recovery rate (P < 0.05) was obtained for isolation of injured cells on selective media. Overall, these results indicate that the agar spray method is an acceptable alternative to the conventional overlay method and is a simpler and more convenient approach to recovery and detection of injured cells.

Optimizing photovoltaic performance in CuInS 2 and CdS quantum dot-sensitized solar cells by using an agar-based gel polymer electrolyte

DOE PAGES

Raphael, E.; Jara, D. H.; Schiavon, M. A.

2017-01-19

Quantum dot-sensitized solar cells (QDSSCs) offer new opportunities to address the clean energy challenge, being one of the top candidates for third generation photovoltaics. Like dye-sensitized solar cells (DSSCs), QDSSCs normally use liquid electrolytes that suffer from issues such as evaporation or leakage. In this study a gel polysulfide electrolyte was prepared containing a natural polymer, agar, and was used as a quasi-solid-state electrolyte in solar cells to replace the conventional liquid electrolytes. This gel electrolyte shows almost the same conductivity as the liquid one. The solar cells were fabricated using CuInS 2 quantum dots (QDs), previously synthesized, deposited onmore » TiO 2 photoanodes by electrophoretic deposition (EPD). CdS was deposited on TiO 2 by successive ionic layer adsorption and reaction (SILAR). Reduced graphene oxide (RGO)–Cu 2S, brass, and thin film CuxS were used as counter electrodes. Compared to a liquid polysulfide water based electrolyte, solar cells based on CuInS 2 and CdS using gel polymer electrolyte (GPE) exhibit greater incident photon to current conversion efficiency (IPCE = 51.7% at 520 nm and 72.7% at 440 nm), photocurrent density (J sc = 10.75 and 13.51 mA cm -2), and power conversion efficiency (η = 2.97 and 2.98%) while exhibiting significantly enhanced stability. The solar cells employing the agar-based gel polymeric electrolyte are about a factor of 0.20 more stable than using a liquid electrolyte. The higher photovoltaic performance is due to the good conductivity and high wettability as well as the superior permeation capability of the gel electrolyte into the mesoporous matrix of a TiO 2 film« less

Optimizing photovoltaic performance in CuInS 2 and CdS quantum dot-sensitized solar cells by using an agar-based gel polymer electrolyte

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raphael, E.; Jara, D. H.; Schiavon, M. A.

Quantum dot-sensitized solar cells (QDSSCs) offer new opportunities to address the clean energy challenge, being one of the top candidates for third generation photovoltaics. Like dye-sensitized solar cells (DSSCs), QDSSCs normally use liquid electrolytes that suffer from issues such as evaporation or leakage. In this study a gel polysulfide electrolyte was prepared containing a natural polymer, agar, and was used as a quasi-solid-state electrolyte in solar cells to replace the conventional liquid electrolytes. This gel electrolyte shows almost the same conductivity as the liquid one. The solar cells were fabricated using CuInS 2 quantum dots (QDs), previously synthesized, deposited onmore » TiO 2 photoanodes by electrophoretic deposition (EPD). CdS was deposited on TiO 2 by successive ionic layer adsorption and reaction (SILAR). Reduced graphene oxide (RGO)–Cu 2S, brass, and thin film CuxS were used as counter electrodes. Compared to a liquid polysulfide water based electrolyte, solar cells based on CuInS 2 and CdS using gel polymer electrolyte (GPE) exhibit greater incident photon to current conversion efficiency (IPCE = 51.7% at 520 nm and 72.7% at 440 nm), photocurrent density (J sc = 10.75 and 13.51 mA cm -2), and power conversion efficiency (η = 2.97 and 2.98%) while exhibiting significantly enhanced stability. The solar cells employing the agar-based gel polymeric electrolyte are about a factor of 0.20 more stable than using a liquid electrolyte. The higher photovoltaic performance is due to the good conductivity and high wettability as well as the superior permeation capability of the gel electrolyte into the mesoporous matrix of a TiO 2 film« less

Protocols for In Vitro Mass Multiplication and Analysis of Medicinally Important Phenolics of a Salep Orchid, Satyrium nepalense D.Don ("Salam Mishri").

PubMed

Babbar, Shashi B; Singh, Deepak K

2016-01-01

Satyrium nepalense is a rare and threatened medicinal orchid, populations of which in its native habitats are dwindling because of indiscriminate collections and habitat destruction, thus necessitating the development of methods for its in situ and ex situ conservation. Because of non-endospermous nature of the seeds and the immature embryos at seed dispersal stage, orchids cannot be seed-propagated as other plants. Micropropagation, using plant tissue culture techniques, offers an effective method for the multiplication of orchids. In this chapter, a five-step efficient reproducible protocol for large-scale in vitro multiplication of Satyrium nepalense is described. The first step involves asymbiotic germination of seeds isolated from immature green pods and cultured on Mitra's medium (M) gelled with 0.8 % agar and supplemented with 2 % sucrose and 1 % peptone (hereafter referred to as basal medium, BM). On this medium, seeds start germinating after a week of culture. Protocorms developed from the seeds are sub-cultured on BM fortified with 4 μM kinetin (Kn) after 8 weeks, for shoot differentiation and multiplication. The shoots developed on Kn-supplemented medium are transferred to BM alone for their elongation for the same period. The elongated shoots are transferred to the rooting medium, comprising BM supplemented with 0.5 or 1.0 μM indole-3-butyric acid, for further 8 weeks. The regenerated plantlets are transferred to a potting mix of sand and vermiculite (1:1) for acclimatization. The tubers and leaves excised from both in vitro-developed plants and those from their native habitats are analyzed and compared for the contents and concentration of medicinally important phenolics using high-performance liquid chromatography (HPLC), details of which are provided in this chapter.

Performance characteristics and estimation of measurement uncertainty of three plating procedures for Campylobacter enumeration in chicken meat.

PubMed

Habib, I; Sampers, I; Uyttendaele, M; Berkvens, D; De Zutter, L

2008-02-01

In this work, we present an intra-laboratory study in order to estimate repeatability (r), reproducibility (R), and measurement uncertainty (U) associated with three media for Campylobacter enumeration, named, modified charcoal cefoperazone deoxycholate agar (mCCDA); Karmali agar; and CampyFood ID agar (CFA) a medium by Biomérieux SA. The study was performed at three levels: (1) pure bacterial cultures, using three Campylobacter strains; (2) artificially contaminated samples from three chicken meat matrixes (total n=30), whereby samples were spiked using two contamination levels; ca. 10(3)cfuCampylobacter/g, and ca. 10(4)cfuCampylobacter/g; and (3) pilot testing in naturally contaminated chicken meat samples (n=20). Results from pure culture experiment revealed that enumeration of Campylobacter colonies on Karmali and CFA media was more convenient in comparison with mCCDA using spread and spiral plating techniques. Based on artificially contaminated samples testing, values of repeatability (r) were comparable between the three media, and estimated as 0.15log(10)cfu/g for mCCDA, 0.14log(10)cfu/g for Karmali, and 0.18log(10)cfu/g for CFA. As well, reproducibility performance of the three plating media was comparable. General R values which can be used when testing chicken meat samples are; 0.28log(10), 0.32log(10), and 0.25log(10) for plating on mCCDA, Karmali agar, and CFA, respectively. Measurement uncertainty associated with mCCDA, Karmali agar, and CFA using spread plating, for combination of all meat matrixes, were +/-0.24log(10)cfu/g, +/-0.28log(10)cfu/g, and +/-0.22log(10)cfu/g, respectively. Higher uncertainty was associated with Karmali agar for Campylobacter enumeration in artificially inoculated minced meat (+/-0.48log(10)cfu/g). The general performance of CFA medium was comparable with mCCDA performance at the level of artificially contaminated samples. However, when tested at naturally contaminated samples, non-Campylobacter colonies gave similar deep red colour as that given by the typical Campylobacter growth on CFA. Such colonies were not easily distinguishable by naked eye. In general, the overall reproducibility, repeatability, and measurement uncertainty estimated by our study indicate that there are no major problems with the precision of the International Organization for Standardization (ISO) 10272-2:2006 protocol for Campylobacter enumeration using mCCDA medium.

Micropropagation of an Exotic Ornamental Plant, Calathea crotalifera, for Production of High Quality Plantlets

PubMed Central

Efzueni Rozali, Shahril; Rashid, Kamaludin A.; Mat Taha, Rosna

2014-01-01

A successful protocol was established for micropropagation in two selected varieties of exotic ornamental plants, Calathea crotalifera. The effects of different sterilization techniques, explant type, and the combination and concentration of plant growth regulators on shoots induction were studied. The axillary shoot buds explants sprouted from rhizomes in soil free conditions showed high induction rate of shoots with lowest contamination percentage when treated with combination of 30% (v/v) NaOCl, 70% (v/v) ethanol, and 0.3% (w/v) HgCl2. In the present study, the highest number of multiple shoots was obtained in MS basal medium supplemented with 3.5 mg/L 6-Benzylaminopurine (BAP), 1.0 mg/L 1-Naphthaleneacetic acid (NAA), 3% sucrose, and 6 g/L plant agar for both varieties and was used as multiplication medium. Microshoots were highly induced when the young shoot bud explants were incised longitudinally prior subculture. Chlorophyll analysis was studied to test the effects of activated charcoal and L-glutamine on reduction of necrosis problem. The maximum roots induction was recorded on MS medium supplemented with 1.0 mg/L 1-Naphthaleneacetic acid (NAA) compared to indolebutyric acid (IBA). The complete regenerated plantlets were successfully acclimatized in the soilless medium under greenhouse condition. This is the first report of rapid mass propagation for C. crotalifera. PMID:25136669

Required characteristics of Paenibacillus polymyxa JB-0501 as potential probiotic.

PubMed

Naghmouchi, Karim; Baah, John; Cudennec, Benoit; Drider, Djamel

2013-08-01

The ability of Paenibacillus polymyxa to inhibit the growth of Escherichia coli generic ATCC 25922 (Escherichia coli ATCC 25922) and to adhere to monolayers of the enterocyte-like human cell line Caco-2 was evaluated. P. polymyxa JB-0501 (P. polymyxa JB-0501), found in a livestock feed probiotic supplement, was compared to P. polymyxa reference strain ATCC 43685 and ATCC 7070 (P. polymyxa ATCC) in terms of carbohydrate utilization and resistance to lysozyme, acid, bile salts, and hydrogen peroxide. JB-0501 grew at pH 4.5 and at H2O2 concentrations less than 7.3 μg/ml and presented a higher affinity to hexadecane and decane. Bile salts at 0.2 % inhibited the growth of all three strains. P. polymyxa JB-0501 and P. polymyxa ATCC 43865 adhered to Caco-2 cell monolayers. The percentage of cells that adhered ranged from about 0.35 to 6.5 % and was partially proportional to the number applied. Contact time (from 15 min to 1 h) had little impact on adhesion. P. polymyxa JB-0501 inhibited the growth of E. coli ATCC 25922, as proven by the diffusion tests in agar. Taken together, these results suggested that P. polymyxa JB-0501 has the potential probiotic properties to justify its consideration as a livestock feed supplement.

Characterization of Bacteroides forsythus Strains from Cat and Dog Bite Wounds in Humans and Comparison with Monkey and Human Oral Strains

PubMed Central

Hudspeth, M. K.; Gerardo, S. Hunt; Maiden, M. F. J.; Citron, D. M.; Goldstein, E. J. C.

1999-01-01

Bacteroides forsythus strains recovered from cat and dog bite wound infections in humans (n = 3), monkey oral strains (n = 3), and the human oral ATCC 43037 type strain were characterized by using phenotypic characteristics, enzymatic tests, whole cell fatty acid analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, PCR fingerprinting, and 16S rDNA (genes coding for rRNA) sequencing. All three bite wound isolates grew on brucella agar supplemented with 5% sheep blood, vitamin K1, and hemin. These strains, unlike the ATCC strain and previously described monkey oral and human clinical strains, did not require N-acetylmuramic acid supplementation for growth as pure cultures. However, their phenotypic characteristics, except for catalase production, were similar to those of previously identified strains. PCR fingerprinting analysis showed differences in band patterns from the ATCC strain. Also, SDS-PAGE and whole cell fatty acid analysis indicated that the dog and cat bite wound strains were similar but not identical to the human B. forsythus ATCC 43037 type strain and the monkey oral strains. The rDNA sequence analysis indicated that the three bite wound isolates had 99.93% homology with each other and 98.9 and 99.22% homology with the human ATCC 43037 and monkey oral strains, respectively. These results suggest that there are host-specific variations within each group. PMID:10325363

Agar/gelatin bilayer gel matrix fabricated by simple thermo-responsive sol-gel transition method.

PubMed

Wang, Yifeng; Dong, Meng; Guo, Mengmeng; Wang, Xia; Zhou, Jing; Lei, Jian; Guo, Chuanhang; Qin, Chaoran

2017-08-01

We present a simple and environmentally-friendly method to generate an agar/gelatin bilayer gel matrix for further biomedical applications. In this method, the thermally responsive sol-gel transitions of agar and gelatin combined with the different transition temperatures are exquisitely employed to fabricate the agar/gelatin bilayer gel matrix and achieve separate loading for various materials (e.g., drugs, fluorescent materials, and nanoparticles). Importantly, the resulting bilayer gel matrix provides two different biopolymer environments (a polysaccharide environment vs a protein environment) with a well-defined border, which allows the loaded materials in different layers to retain their original properties (e.g., magnetism and fluorescence) and reduce mutual interference. In addition, the loaded materials in the bilayer gel matrix exhibit an interesting release behavior under the control of thermal stimuli. Consequently, the resulting agar/gelatin bilayer gel matrix is a promising candidate for biomedical applications in drug delivery, controlled release, fluorescence labeling, and bio-imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of Pfizer selective enterococcus and KF media for recovery of fecal streptococci from water by membrane filtration.

PubMed Central

Brodsky, M H; Schiemann, D A

1976-01-01

Pfizer selective enterococcus (PSE) and KF agars were compared for their recovery of fecal streptococci from sewage effluent on membrane filters. The results showed that PSE agar is highly selective for the enterococci. The tan color resulting from esculin hydrolysis, which was not always visible on the surfaces of the colonies, is not considered a necessary differential characteristic on PSE agar since more than 90% of all colonies recovered on membrane filters were confirmed as fecal streptococci and 86% were confirmed as enterococci. The detection of esculin hydrolysis on membrane filters was not improved by using the new Millipore type HC filter. KF agar recovered significantly greater numbers of organisms but was not as selective, with 83% of the typical colonies being confirmed as fecal streptococci and 54% as enterococci. An attempt to improve the selectivity of KF agar while retaining its inclusiveness by incubation at 45 C was not successful. PMID:818956

One-week 96-well soft agar growth assay for cancer target validation.

PubMed

Ke, Ning; Albers, Aaron; Claassen, Gisela; Yu, De-hua; Chatterton, Jon E; Hu, Xiuyuan; Meyhack, Bernd; Wong-Staal, Flossie; Li, Qi-Xiang

2004-05-01

Soft agar growth, used to measure cell anchorage-independent proliferation potential, is one of the most important and most commonly used assays to detect cell transformation. However, the traditional soft agar assay is time-consuming, labor-intensive, and plagued with inconsistencies due to individual subjectivity. It does not, therefore, meet the increasing demands of today's oncology drug target screening or validation processes. This report describes an alternative 96-well soft agar growth assay that can function as a replacement for the traditional method and overcomes the aforementioned limitations. It offers the following advantages: a shortened assay duration (1 week instead of 4 weeks) that makes transient transfection or treatment possible; plate reader quantification of soft agar growth (measuring cloning efficiency and colony size); and a significant reduction in required labor. Higher throughput also makes it possible to process large numbers of samples and treatments simultaneously and in a much more efficient manner, while saving precious workspace and overall cost.

Selective vs. nonselective media and direct plating vs. enrichment technique in isolation of Vibrio cholerae: recommendations for clinical laboratories.

PubMed

Rennels, M B; Levine, M M; Daya, V; Angle, P; Young, C

1980-09-01

The occurrence of human cholera along the Gulf of Mexico and the isolation of Vibrio cholerae O1 from the Gulf and Chesapeake Bay make it imperative that microbiology laboratories along estuaries develop the capabilities to culture for these pathogens. In attempts to devise a simplified but efficient culture procedure, a selective medium, thiosulfate-citrate-bile salts-sucrose (TCBS) agar, was compared with a nonselective medium, gelatin agar (GA), and the utility of enrichment was examined. TCBS agar detected 99% of the stools found to be positive by all techniques combined, whereas GA identified only 80%. Of acute diarrheal stools, 96% were positive on direct plating, whereas only 66% of formed stools containing V. cholerae were detected by direct plating. Stools from patients with acute diarrhea can be plated directly into TCBS agar alone; stools from persons shedding low numbers of organisms (such as contacts, carriers, or patients receiving antibiotics) should be incubated first in an enrichment broth and then on TCBS agar.

Intelligent pH indicator film composed of agar/potato starch and anthocyanin extracts from purple sweet potato.

PubMed

Choi, Inyoung; Lee, Jun Young; Lacroix, Monique; Han, Jaejoon

2017-03-01

A new colorimetric pH indicator film was developed using agar, potato starch, and natural dyes extracted from purple sweet potato, Ipomoea batatas. Both agar and potato starch are solid matrices used to immobilize natural dyes, anthocyanins. The ultraviolet-visible (UV-vis) spectrum of anthocyanin extract solutions and agar/potato starch films with anthocyanins showed color variations to different pH values (pH 2.0-10.0). Fourier transform infrared (FT-IR) and UV-vis region spectra showed compatibility between agar, starch, and anthocyanin extracts. Color variations of pH indicator films were measured by a colorimeter after immersion in different pH buffers. An application test was conducted for potential use as a meat spoilage sensor. The pH indicator films showed pH changes and spoilage point of pork samples, changing from red to green. Therefore, the developed pH indicator films could be used as a diagnostic tool for the detection of food spoilage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessing the microstructural and rheological changes induced by food additives on potato puree.

PubMed

Dankar, Iman; Haddarah, Amira; El Omar, Fawaz; Sepulcre, Francesc; Pujolà, Montserrat

2018-02-01

The effects of agar, alginate, lecithin and glycerol on the rheological properties of commercial potato puree were investigated and interpreted in terms of starch microstructural changes, and the applicability of the Cox-Merz rule was evaluated. Each additive was applied separately at two concentrations (0.5 and 1%). Microscopic observations revealed more swollen starch aggregations in lecithin and glycerol compared with those of potato puree and agar, consequently affecting the rheological properties of potato puree. All samples exhibited shear thinning non-Newtonian behaviour. Rheological measurements were strongly concentration dependent. At 0.5% concentration, additives exerted decreases in all the rheological properties of potato puree in the order of glycerol>alginate>lecithin>agar, while at 1% concentration, the order changed to glycerol>lecithin>alginate, whereas 1% agar behaved differently, increasing all rheological values. This study also showed that agar and alginate in addition to potato puree could be valuable and advantageous for further technological processes, such as 3D printing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tularemia: Current Diagnosis and Treatment Options

DTIC Science & Technology

2008-04-01

for growing F. tularensis, which include cysteine blood agar, Thayer–Martin agar and cysteine heart agar with 9% heated sheep red blood cells (CHAB...samples contain inhibitors to PCR reactions, such the heme component of red blood cells [36]. These inhibitors cause the limit of detection of the organism...signaling and cytokine secretion in mouse monocytic and human peripheral blood mononuclear cells . Microb. Pathog. 38, 239–247 (2005). 16 Hrstka R

Mechanism of Enhancement of Virus Plaques by Cationic Polymers

PubMed Central

Wallis, Craig; Melnick, Joseph L.

1968-01-01

It has been assumed that plaque enhancement by cationic polymers is due to their binding of sulfated polysaccharides in agar. However, viruses that are enhanced by cationic polymers, diethylaminoethyl-dextran, and protamine were found not to be inhibited by polyanions in agar under the usual overlay conditions. In the case of adenovirus, enhancement by protamine seems to be due to the protamine serving as a source of arginine; enzymes released from the cultured cells digest the protamine and provide a reservoir of arginine for the cells. Other viruses (herpes and echovirus types 3, 4, 5, and 6) known to be susceptible to agar inhibitors were found to be enhanced by cationic polymers even under starch gel and methylcellulose overlays, which are free of polyanions. Since cationic polymers enhance the diffusion of virus through agar or starch gel, plaque enhancement seems to be the result of the gel becoming positively charged so that viruses can move effectively through them. The observation that starch gel and methylcellulose enhance plaque formation with viruses known to be inhibited under agar was also reinvestigated. When the consistency of the agar gel was reduced to the same viscosity of starch gel and methylcellulose overlays, the same plaque counts and sizes were observed under all three overlays. PMID:4986901

Long-term biological hydrogen production by agar immobilized Rhodobacter capsulatus in a sequential batch photobioreactor.

PubMed

Elkahlout, Kamal; Alipour, Siamak; Eroglu, Inci; Gunduz, Ufuk; Yucel, Meral

2017-04-01

In this study, agar immobilization technique was employed for biological hydrogen production using Rhodobacter capsulatus DSM 1710 (wild type) and YO3 (hup-mutant) strains in sequential batch process. Different agar and glutamate concentrations were tested with defined nutrient medium. Agar concentration 4% (w/v) and 4 mM glutamate were selected for bacterial immobilization in terms of rate and longevity of hydrogen production. Acetate concentration was increased from 40 to 60-100 and 60 mM gave best results with both bacterial strains immobilized in 4% (w/v) agar. Cell concentration was increased from 2.5 to 5 mg dcw mL -1 agar and it was found that increasing cell concentration of wild-type strain caused decrease in yield and productivity while these parameters improved by increasing cell concentration of mutant strain. Also, the hydrogen production time has extended from 17 days up to 60 days according to the process conditions and parameters. Hydrogen production by immobilized photosynthetic bacteria is a convenient technology for hydrogen production as it enables to produce hydrogen with high organic acid concentrations comparing to suspended cultures. Besides, immobilization increases the stability of the system and allowed sequential batch operation for long-term application.

Migration of Chemotactic Bacteria in Soft Agar: Role of Gel Concentration

PubMed Central

Croze, Ottavio A.; Ferguson, Gail P.; Cates, Michael E.; Poon, Wilson C.K.

2011-01-01

We study the migration of chemotactic wild-type Escherichia coli populations in semisolid (soft) agar in the concentration range C = 0.15–0.5% (w/v). For C≲0.35%, expanding bacterial colonies display characteristic chemotactic rings. At C = 0.35%, however, bacteria migrate as broad circular bands rather than sharp rings. These are growth/diffusion waves arising because of suppression of chemotaxis by the agar and have not been previously reported experimentally to our knowledge. For C = 0.4–0.5%, expanding colonies do not span the depth of the agar and develop pronounced front instabilities. The migration front speed is weakly dependent on agar concentration at C < 0.25%, but decreases sharply above this value. We discuss these observations in terms of an extended Keller-Segel model for which we derived novel transport parameter expressions accounting for perturbations of the chemotactic response by collisions with the agar. The model makes it possible to fit the observed front speed decay in the range C = 0.15–0.35%, and its solutions qualitatively reproduce the observed transition from chemotactic to growth/diffusion bands. We discuss the implications of our results for the study of bacteria in porous media and for the design of improved bacteriological chemotaxis assays. PMID:21806920

Enhancing the culturability of bacteria from the gastrointestinal tract of farmed adult turbot Scophthalmus maximus

NASA Astrophysics Data System (ADS)

Xing, Mengxin; Hou, Zhanhui; Qu, Yanmei; Liu, Bin

2014-03-01

Eighteen agar media were tested for the culture of gut-associated bacteria from farmed adult turbot ( Scophthalmus maximus), including 16 agar media with or without 1% gastrointestinal (GI) supernatant, or with 2% or 4% GI supernatant. A total of 1 711 colonies were analyzed and 24 operational taxonomic units (OTUs) were identified. The greatest bacterial diversity was isolated on Zobell 2216E/Zobell 2216E+ agar media, whereas MRS/MRS+ agar media produced a low diversity of colonies. Agar media with GI supernatant (1%, 2%, or 4%) showed increased diversity and yielded different profiles of OTUs from the corresponding original media, suggesting that GI supernatant provides substances that enhance the culture efficiency of bacteria from the turbot GI tract. The large majority of the colonies (82%) were γ-Proteobacteria, whereas 15.6% and 2.4% of colonies were Firmicutes and Actinobacteria, respectively. At the genus level, 49.4% of all colonies were assigned to Vibrio. Other potential pathogens, including Pseudomonas, Photobacterium, and Enterobacter, and potential probiotics, including Bacillus, Paenibacillus, and Pseudomonas, were also isolated on agar media. Most cultured bacteria belonged to species that were first described in the turbot GI tract. The impact of these species on turbot physiology and health should be investigated further.

Rapid Detection and Identification of Candidemia by Direct Blood Culturing on Solid Medium by Use of Lysis-Centrifugation Method Combined with Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS).

PubMed

Idelevich, Evgeny A; Grünastel, Barbara; Becker, Karsten

2017-01-01

Candida sepsis is a life-threatening condition with increasing prevalence. In this study, direct blood culturing on solid medium using a lysis-centrifugation procedure enabled successful Candida species identification by matrix-assisted laser desorption-ionization time of flight mass spectrometry on average 3.8 h (Sabouraud agar) or 7.4 h (chocolate agar) before the positivity signal for control samples in Bactec mycosis-IC/F or Bactec Plus aerobic/F bottles, respectively. Direct culturing on solid medium accelerated candidemia diagnostics compared to that with automated broth-based systems. Copyright © 2016 American Society for Microbiology.

Role of Mrx Fimbriae of Xenorhabdus nematophila in Competitive Colonization of the Nematode Host ▿

PubMed Central

Snyder, Holly; He, Hongjun; Owen, Heather; Hanna, Chris; Forst, Steven

2011-01-01

Xenorhabdus nematophila engages in mutualistic associations with the infective juvenile (IJ) stage of specific entomopathogenic nematodes. Mannose-resistant (Mrx) chaperone-usher-type fimbriae are produced when the bacteria are grown on nutrient broth agar (NB agar). The role of Mrx fimbriae in the colonization of the nematode host has remained unresolved. We show that X. nematophila grown on LB agar produced flagella rather than fimbriae. IJs propagated on X. nematophila grown on LB agar were colonized to the same extent as those propagated on NB agar. Further, progeny IJs were normally colonized by mrx mutant strains that lacked fimbriae both when bacteria were grown on NB agar and when coinjected into the insect host with aposymbiotic nematodes. The mrx strains were not competitively defective for colonization when grown in the presence of wild-type cells on NB agar. In addition, a phenotypic variant strain that lacked fimbriae colonized as well as the wild-type strain. In contrast, the mrx strains displayed a competitive colonization defect in vivo. IJ progeny obtained from insects injected with comixtures of nematodes carrying either the wild-type or the mrx strain were colonized almost exclusively with the wild-type strain. Likewise, when insects were coinjected with aposymbiotic IJs together with a comixture of the wild-type and mrx strains, the resulting IJ progeny were predominantly colonized with the wild-type strain. These results revealed that Mrx fimbriae confer a competitive advantage during colonization in vivo and provide new insights into the role of chaperone-usher fimbriae in the life cycle of X. nematophila. PMID:21856828

Microbiological characteristics of "androlla", a Spanish traditional pork sausage.

PubMed

García Fontán, María C; Lorenzo, José M; Parada, Ana; Franco, Inmaculada; Carballo, Javier

2007-02-01

Counts of total aerobic mesophilic microflora, lactic acid bacteria, salt-tolerant microflora, Enterobacteriaceae, enterococci, moulds and yeasts, and staphylococci, and some physico-chemical parameters (total solids, NaCl and nitrate contents and pH and aw values) were determined in 20 units of "androlla", a traditional dry-fermented sausage made in the NW of Spain. In general, high counts of all the investigated microbial groups were observed, with average values of 8.99 +/- 0.46 log cfu/g for the total aerobic mesophilic microflora, 9.11 +/- 0.16 log cfu/g for the lactic acid bacteria, 6.87 +/- 0.68 log cfu/g for the salt-tolerant microflora, 2.80+/-1.85 log cfu/g for the Enterobacteriaceae, 3.25 +/- 1.86 log cfu/g for the enterococci, 4.30 +/- 1.73 log cfu/g for the moulds and yeasts, and 3.62 +/- 0.60 log cfu/g for the staphylococci. From MRS agar, SPC agar + 7.5% NaCl, VRBG agar, and KAA agar, 10 colonies were randomly taken from each androlla unit and from each culture medium. A total of 200 strains per culture medium were then identified using the classical methods. Among the isolates from MRS agar, Lactobacillus sakei predominated, followed by Lactobacillus curvatus, Lactobacillus alimentarius and Lactobacillus plantarum. Of the 200 isolates obtained from SPC agar + 7.5% NaCl, only 56 strains belonged to the Staphylococcaceae or Micrococcaceae families. Among the Staphylococcaceae, Staphylococcus xylosus was the main species, followed by Staph. epidermidis; Staph. equorum, Staph. capitis and Staph. saprophyticus were isolated in very low proportions. Among the Micrococcaceae, Micrococcus luteus predominated, followed by Micrococcus lylae, Kocuria varians and Kocuria kristinae. Of the 150 isolates obtained from VRBG agar, Hafnia alvei was the main species, followed by Serratia liquefaciens and Enterobacter amnigenus; six isolates were identified as Salmonella. Among the 190 isolates obtained from KAA agar, 122 were considered enterococci; 20 isolates were identified as Enterococcus faecium, one as Enterococcus faecalis and 101 as Enterococcus inter faecalis-faecium.

Evaluation of CP Chromo Select Agar for the enumeration of Clostridium perfringens from water.

PubMed

Manafi, Mammad; Waldherr, Kerstin; Kundi, Michael

2013-10-01

The European Directive on drinking water quality has included mCP agar as the reference method for recovering Clostridium perfringens from drinking waters. In the present study, three media (mCP, TSCF and CP Chromo Select Agar) were evaluated for recovery of C. perfringens in different surface water samples. Out of 139 water samples, using a membrane filtration technique, 131 samples (94.2%) were found to be presumptively positive for C. perfringens in at least one of the culture media. Green colored colonies on CP Chromo Select Agar (CCP agar) were counted as presumptive C. perfringens isolates. Out of 483 green colonies on CCP agar, 96.3% (465 strains, indole negative) were identified as C. perfringens, and 15 strains (3.1%) were indole positive and were identified as Clostridium sordellii, Clostridium bifermentans or Clostridium tetani. Only 3 strains (0.6%) gave false positive results and were identified as Clostridium fallax, Clostridium botulinum, and Clostridium tertium. Variance analysis of the data obtained shows statistically no significant differences in the counts obtained between media employed in this work. The mCP method is very onerous for routine screening and bacterial colonies could not be used for further biochemical testing. The colonies on CCP and TSCF were easy to count and subculture for confirmation tests. TSCF detects sulfite-reducing clostridia, including species other than C. perfringens, and in some cases excessive blackening of the agar frustrated counting of the colonies. If the contamination was too high, TSCF did not consistently produce black colonies and as a consequence, the colonies were white and gave false negative results. On the other hand, the identification of typical and atypical colonies isolated from all media demonstrated that CCP agar was the most useful medium for C. perfringens recovery in water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Performance of CHROMAGAR candida and BIGGY agar for identification of yeast species

PubMed Central

Yücesoy, Mine; Marol, Serhat

2003-01-01

Background The importance of identifying the pathogenic fungi rapidly has encouraged the development of differential media for the presumptive identification of yeasts. In this study two differential media, CHROMagar Candida and bismuth sulphite glucose glycine yeast agar, were evaluated for the presumptive identification of yeast species. Methods A total number of 270 yeast strains including 169 Candida albicans, 33 C. tropicalis, 24 C. glabrata, 18 C. parapsilosis, 12 C. krusei, 5 Trichosporon spp., 4 C. kefyr, 2 C. lusitaniae, 1 Saccharomyces cerevisiae and 1 Geotrichum candidum were included. The strains were first identified by germ tube test, morphological characteristics on cornmeal tween 80 agar and Vitek 32 and API 20 C AUX systems. In parallel, they were also streaked onto CHROMagar Candida and bismuth sulphite glucose glycine yeast agar plates. The results were read according to the color, morphology of the colonies and the existance of halo around them after 48 hours of incubation at 37°C. Results The sensitivity and specificity values for C. albicans strains were found to be 99.4, 100% for CHROMagar Candida and 87.0, 75.2% for BiGGY agar, respectively. The sensitivity of CHROMagar Candida to identify C. tropicalis, C. glabrata and C. krusei ranged between 90.9 and 100% while the specificity was 100%. The sensitivity rates for BiGGY agar were 66.6 and 100% while the specificity values were found to be 95.4 and 100% for C. tropicalis and C. krusei, respectively. Conclusions It can be concluded that the use of CHROMagar Candida is an easy and reliable method for the presumptive identification of most commonly isolated Candida species especially C. albicans, C. tropicalis and C. krusei. The lower sensitivity and specificity of BiGGY agar to identify commonly isolated Candida species potentially limits the clinical usefulness of this agar. PMID:14613587

Can the diagnosis of recurrent vulvovaginal candidosis be improved by use of vaginal lavage samples and cultures on chromogenic agar?

PubMed Central

Novikova, N; Rodrigues, A; Mårdh, P A

2002-01-01

OBJECTIVE: To investigate if introital and vaginal flushing samples inoculated on chromogenic agar could increase the recovery rate and rapid identification of Candida and non-albicans species, as compared to culture of posterior vaginal fornix samples on Sabouraud agar and speciation of isolates by biochemical tests. METHODS: Samples from the introitus and the posterior vaginal fornix and vaginal lavage samples were collected from 91 women with a history suggestive of recurrent vulvovaginal candidosis (RVVC), and with a suspected new attack of the condition. The specimens were cultured on Sabouraud and CHROMagar. Speciation of yeast isolates was made on the chromogenic agar by API 32C kits and by an atomized system (Vitek). RESULTS: Forty-six (51%) women were positive for Candida from one or more of the samples. The introital cultures were positive in 43 (47%) women, both on Sabouraud and chromogenic agar. From the posterior vaginal fomix, 42 (46%) women were positive on the Sabouraud and 43 (47%) on chromogenic agar cultures, while the vaginal lavage cultures yielded Candida on those two media in 40 (44%) and 41 (45%) cases, respectively. Candida albicans was the most frequent species recovered, from 40 (87%) cases, followed by C. krusei in 4 (9%), C. glabrata in 2 (4%), and C. parapsilosis in one case. There was only one woman who had a mixed yeast infection, by C. albicans and C. krusei. There was only one discrepancy in the speciation as demonstrated by mean of chromogenic agar and API 32C kit. CONCLUSIONS: Neither cultures of introital nor of vaginal lavage samples increases the detection rate of Candida in RVVC cases as compared to cultures of posterior vaginal fornix samples. Use of chromogenic agar is a convenient and reliable means to detect colonization by Candida and differentiate between C. albicans and non-albicans species. PMID:12530485

[Isolation of Aspergillus tritici from internal environment (Chile): Ecological and clinical scope].

PubMed

Vieille Oyarzo, Peggy; Cruz Choappa, Rodrigo; Piontelli Laforet, Eduardo

2018-03-29

Indoor environments provide important protective habitats for humans, who live or work in them most of the time. Many of these environments lack ventilation, which affects the composition of microbial communities, especially that of the fungal community. The aim of this study is to report the isolation of Aspergillus section Candidi from indoor environments of the School of Medicine at Universidad de Valparaiso, Chile, and identification through morpho-physiological and molecular approaches. Their ecological and clinical features were highlighted. An environmental non-volumetric sampling was performed on PDA medium; 2 petri dishes were exposed in 10 different places to select the Aspergillus samples. Subcultures were performed on agar Czapek with yeast extract (CYA), malt extract agar (MEA) and creatin sacarose agar (CREA) media only for the morpho-physiological and later the molecular identification of white spore species. Of the 20 samples analyzed, one Aspergillus belonging to Candidi section was isolated. Based on its morphology and molecular features, it was classified as Aspergillustritici Mehrotra & Basu. Its ecology and medical relevance are reviewed and discussed. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

New closed tube loop mediated isothermal amplification assay for prevention of product cross-contamination

PubMed Central

Karthik, K.; Rathore, Rajesh; Thomas, Prasad; Arun, T.R.; Viswas, K.N.; Dhama, Kuldeep; Agarwal, R.K.

2014-01-01

Loop mediated isothermal amplification (LAMP) assay, a promising diagnostic test, has been developed for detection of different pathogens of human as well as animals. Various positive points support its use as a field level test but the major problem is product cross contamination leading to false positive results. Different methods were adopted by various researchers to control this false positive amplification due to cross contamination but all have their own advantages and disadvantages. A new closed tube LAMP assay based on agar dye capsule was developed in the present study and this technique has some advantages over the other closed tube technique.•Agar at the concentration of 1.5% was used to sandwich SYBR green dye I with the aid of intradermal syringe. This agar dye capsule was placed over the LAMP reaction mixture before it was amplified.•To eliminate the hazardous nature of Ultra Violet (UV) light during result visualization of LAMP products, the present study demonstrates the use of Light Emitting Diode (LED) lights for result visualization.•LAMP was carried out for Brucella species detection using this modified techniques yielding good results without any cross contamination and LED showed similar fluorescence compared to UV. PMID:26150945

New closed tube loop mediated isothermal amplification assay for prevention of product cross-contamination.

PubMed

Karthik, K; Rathore, Rajesh; Thomas, Prasad; Arun, T R; Viswas, K N; Dhama, Kuldeep; Agarwal, R K

2014-01-01

Loop mediated isothermal amplification (LAMP) assay, a promising diagnostic test, has been developed for detection of different pathogens of human as well as animals. Various positive points support its use as a field level test but the major problem is product cross contamination leading to false positive results. Different methods were adopted by various researchers to control this false positive amplification due to cross contamination but all have their own advantages and disadvantages. A new closed tube LAMP assay based on agar dye capsule was developed in the present study and this technique has some advantages over the other closed tube technique.•Agar at the concentration of 1.5% was used to sandwich SYBR green dye I with the aid of intradermal syringe. This agar dye capsule was placed over the LAMP reaction mixture before it was amplified.•To eliminate the hazardous nature of Ultra Violet (UV) light during result visualization of LAMP products, the present study demonstrates the use of Light Emitting Diode (LED) lights for result visualization.•LAMP was carried out for Brucella species detection using this modified techniques yielding good results without any cross contamination and LED showed similar fluorescence compared to UV.

Selective differential human blood bilayer media for isolation of Gardnerella (Haemophilus) vaginalis.

PubMed Central

Totten, P A; Amsel, R; Hale, J; Piot, P; Holmes, K K

1982-01-01

New selective and differential human blood bilayer agar media with Tween 80 (HBT medium) or without Tween 80 (HB medium), developed for the isolation of Gardnerella (Haemophilus) vaginalis, permitted significantly higher G. vaginalis isolation rates than have been obtained for other media used for this purpose. HB medium consists of a basal layer of Columbia agar base containing colistin and naladixic acid with added amphotericin B and an overlayer of the same composition plus 5% human blood. HBT agar also contains Proteose Peptone No. 3 (Difco Laboratories) and Tween 80 in the basal layer and the overlayer. Both Tween 80 and the bilayer composition enhanced G. vaginalis production of human blood hemolysis, permitting detection of this organism even in the presence of heavy growth of other vaginal flora. The use of HB or HBT medium thus permitted the demonstration that G. vaginalis was present in vaginal fluid from a large percentage (up to 68%) of normal women. However, the concentration of G. vaginalis was found by semiquantitative analysis to be significantly higher in vaginal fluid from women with nonspecific vaginitis than in fluid from normal women. Images PMID:6764766

Ultra-sensitive detection of tumorigenic cellular impurities in human cell-processed therapeutic products by digital analysis of soft agar colony formation.

PubMed

Kusakawa, Shinji; Yasuda, Satoshi; Kuroda, Takuya; Kawamata, Shin; Sato, Yoji

2015-12-08

Contamination with tumorigenic cellular impurities is one of the most pressing concerns for human cell-processed therapeutic products (hCTPs). The soft agar colony formation (SACF) assay, which is a well-known in vitro assay for the detection of malignant transformed cells, is applicable for the quality assessment of hCTPs. Here we established an image-based screening system for the SACF assay using a high-content cell analyzer termed the digital SACF assay. Dual fluorescence staining of formed colonies and the dissolution of soft agar led to accurate detection of transformed cells with the imaging cytometer. Partitioning a cell sample into multiple wells of culture plates enabled digital readout of the presence of colonies and elevated the sensitivity for their detection. In practice, the digital SACF assay detected impurity levels as low as 0.00001% of the hCTPs, i.e. only one HeLa cell contained in 10,000,000 human mesenchymal stem cells, within 30 days. The digital SACF assay saves time, is more sensitive than in vivo tumorigenicity tests, and would be useful for the quality control of hCTPs in the manufacturing process.

Ultra-sensitive detection of tumorigenic cellular impurities in human cell-processed therapeutic products by digital analysis of soft agar colony formation

PubMed Central

Kusakawa, Shinji; Yasuda, Satoshi; Kuroda, Takuya; Kawamata, Shin; Sato, Yoji

2015-01-01

Contamination with tumorigenic cellular impurities is one of the most pressing concerns for human cell-processed therapeutic products (hCTPs). The soft agar colony formation (SACF) assay, which is a well-known in vitro assay for the detection of malignant transformed cells, is applicable for the quality assessment of hCTPs. Here we established an image-based screening system for the SACF assay using a high-content cell analyzer termed the digital SACF assay. Dual fluorescence staining of formed colonies and the dissolution of soft agar led to accurate detection of transformed cells with the imaging cytometer. Partitioning a cell sample into multiple wells of culture plates enabled digital readout of the presence of colonies and elevated the sensitivity for their detection. In practice, the digital SACF assay detected impurity levels as low as 0.00001% of the hCTPs, i.e. only one HeLa cell contained in 10,000,000 human mesenchymal stem cells, within 30 days. The digital SACF assay saves time, is more sensitive than in vivo tumorigenicity tests, and would be useful for the quality control of hCTPs in the manufacturing process. PMID:26644244

Comparison of susceptibility test methods to detect penicillin susceptibility in Streptococcus pneumoniae isolates.

PubMed

Mohd Nasir, Mohd Desa; Parasakthi, Navaratnam

2004-06-01

The increasing prevalence of penicillin-resistant Streptococuus pneumoniae urges for fast and accurate susceptibility testing methods. This study evaluated the comparability of three commonly used techniques; disk diffusion, E-test and agar dilution, to detect penicillin susceptibility in clinical isolates of S. pneumoniae. Fifty pneumococcal isolates, obtained from patients at the University of Malaya Medical Centre, were selected to include both penicillin-susceptible strains and those that had decreased susceptibility (resistant and intermediate) to penicillin. The minimum inhibitory concentration (MIC) values of penicillin to serve as the reference was determined by the agar dilution method in which, based on the MIC breakpoints recommended by the National Committee for Clinical Laboratory Standards (NCCLS), 27 strains had decreased susceptibility to penicillin with 17 strains resistant and 10 intermediate. Comparing to the agar dilution method, oxacillin disk diffusion test detected all strains with decreased penicillin susceptibility as such while E-test showed a close agreement of susceptibility (92%) of the isolates to penicillin. This confirmed that oxacillin is a good screening test for S. pneumoniae isolates with decreased susceptibility to penicillin while E-test is very reliable for rapid and accurate detection of penicillin susceptibility.

Comparative Study of Worldwide Species of Genus Lentinus (=Lentinula, Higher Basidiomycetes) Based on Linear Mycelium Growth.

PubMed

Mata, Juan Luis; Mishra, Nutan Tulapurkar

2015-01-01

Species of mushroom genus Lentinus (=Lentinula) are best known for the commercially important and extensively studied culinary-medicinal shiitake, L. edodes. A few mycelium growth studies have focused on Lentinus boryana, but information is lacking for L. raphanica and L. aciculospora, endemic to the Americas. In this study, 14 dikaryon strains representing 5 Lentinus species were grown on 5 nutritive agar media at increments of 5°C. Growth for each species was significantly slower on corn meal agar, but no differences were found among malt extract, potato dextrose, malt peptone, and yeast malt extract agars. Lentinus aciculospora and L. boryana consistently exhibited the slowest mycelium growth rates among all species and across all temperatures tested, with optima at 15°C and 20°C. The fastest mycelium growth rates for L. edodes, L. novaezelandiae, and L. raphanica occurred at 25°C. Strains of the latter continued to grow well at 30°C, whereas growth of the other 2 species declined significantly. Differences in mycelium growth rates for American strains could be partially explained by their geographic locations, indicating that understanding this physiological parameter has important ramifications for the edible mushroom industry.

Reflected scatterometry for noninvasive interrogation of bacterial colonies

USDA-ARS?s Scientific Manuscript database

A phenotyping of bacterial colonies on agar plates using forward-scattering diffraction-pattern analysis provided promising classification of several different bacteria such as Salmonella, Vibrio, Listeria, and E. coli. Since the technique is based on forward-scattering phenomena, light transmittanc...

Effect of Food Thickener on Dissolution and Laxative Activity of Magnesium Oxide Tablets in Mice.

PubMed

Tomita, Takashi; Goto, Hidekazu; Yoshimura, Yuya; Kato, Kazushige; Yoshida, Tadashi; Tanaka, Katsuya; Sumiya, Kenji; Kohda, Yukinao

2016-01-01

The present study examined the dissolution of magnesium oxide (MgO) from MgO tablets placed in a food thickening agent (food thickener) and its effects on laxative activity. We prepared mixtures of MgO tablets suspended in an aqueous suspension and food thickeners in order to evaluate the dissolution of MgO. The results of the dissolution tests revealed that agar-based food thickeners did not affect the MgO dissolution. In contrast, some xanthan gum-based food-thickener products show dissolution rates with certain mixtures containing disintegrated MgO tablets suspended in a food thickener that decrease over time. However, other xanthan gum-based food-thickener products show dissolution rates that decrease immediately after mixing, regardless of the time they were allowed to stand. In order to investigate the laxative activity of MgO, we orally administered a mixture of MgO suspension and food thickener to mice and observed their bowel movements. The animal experiments showed that when agar-based food thickeners were used, the laxative activity of MgO was not affected, but it decreased when xanthan gum-based food thickeners were used.

Considerations in developing lipid-based nutrient supplements for prevention of undernutrition: experience from the International Lipid-Based Nutrient Supplements (iLANS) Project.

USDA-ARS?s Scientific Manuscript database

The International Lipid-Based Nutrient Supplements (iLiNS) Project began in 2009 with the goal of contributing to the evidence base regarding the potential of lipid-based nutrient supplements (LNS) to prevent undernutrition in vulnerable populations. The first project objective was the development o...

Considerations in developing lipid-based nutrient supplements for prevention of undernutrition: experience from the International Lipid-Based Nutrient Supplements (iLiNS)

USDA-ARS?s Scientific Manuscript database

The International Lipid-Based Nutrient Supplements (iLiNS) Project began in 2009 with the goal of contributing to the evidence base regarding the potential of lipid-based nutrient supplements (LNS) to prevent undernutrition in vulnerable populations. The first project objective was the development o...

Agar-Silica-Gel Heating Phantom May Be Suitable for Long-Term Quality Assurance of MRgHIFU

NASA Astrophysics Data System (ADS)

Partanen, Ari

2009-04-01

In MRgHIFU, the purpose of frequent quality assurance is to detect changes in system performance to prevent adverse effects during treatments. Due to high ultrasound intensities in MRgHIFU, it is essential to assure that the procedure is safe and efficacious and that image-based guidance of the treatment is reliable. We aimed to develop a guideline for MRgHIFU QA by acquiring MR temperature maps during ultrasonic heating of an agar-silica-gel phantom over a four month-period using three separate MRgHIFU uterine leiomyoma treatment systems. From this data, the stability of the maximum temperature elevation, the targeting accuracy, and the dimensions of the heated volume were analyzed. Additionally, we studied the sensitivity of these parameters to reveal hypothetical decrease in HIFU performance. After calibration, the mean targeting offsets of the heated volume were observed to be less than 2 mm in the three orthogonal directions. The measured maximum temperature elevation and the length and the width of the heated volume remained consistent throughout the four-month period. Furthermore, it was found that the parameters under investigation were sensitive to reveal the decreased HIFU performance. We conclude that an agar-silica -based phantom is suitable for targeting accuracy and heating properties QA of MRgHIFU system even in long-term use. Moreover, this simple QA method may be used to reveal small changes in HIFU performance assuring consistent functionality and safety of the MRgHIFU system.

Evaluation of the antibacterial efficacy of diesters of azelaic acid.

PubMed

Charnock, Colin; Brudeli, Bjarne; Klaveness, Jo

2004-04-01

A number of diesters of the topical dermatosis treatment azelaic (nonanedioic) acid were prepared and tested for antibacterial effect. Two esters, bis-[(hexanoyloxy)methyl] nonanedioate and especially bis-[(butanoyloxy)methyl] nonanedioate showed promising activity against acne related bacteria in vitro. No activity of azelaic acid was detected in Mueller Hinton II agar at pH 7.3 when using the agar diffusion method, whereas both esters gave zones of growth inhibition. At pH 5.6, activity of azelaic acid was detected. At this pH, the zones of inhibition and MIC values obtained with azelaic acid were smaller than those of bis-[(butanoyloxy)methyl] nonanedioate for all test organisms. A preparation for topical use containing 20% (w/w) bis-[(butanoyloxy)methyl] nonanedioate, and the commercially available Skinoren (20% (w/w) azelaic acid), were compared for antibacterial effect against cutaneous bacteria using contact plate analyses of the skin. Though Skinoren was usually most effective, the differences were not statistically significant. Furthermore, bacteria surviving contact with the topical preparations were invariably more sensitive to the ester than to azelaic acid upon subculturing onto agar (pH 5.6) containing either preparation at 0.2-0.7 mg/ml. This might indicate that other factors, such as the composition of the cream base, mitigate the antibacterial activity of the ester. It is proposed that the pharmacological and microbiological properties of bis-[(butanoyloxy)methyl] nonanedioate are worthy of further study based on an extended screening of acne sufferers.

Survival or growth of inoculated Escherichia coli O157:H7 and Salmonella on yellow onions (Allium cepa) under conditions simulating food service and consumer handling and storage.

PubMed

Lieberman, Vanessa M; Zhao, Irene Y; Schaffner, Donald W; Danyluk, Michelle D; Harris, Linda J

2015-01-01

Whole and diced yellow onions (Allium cepa) were inoculated with five-strain cocktails of rifampin-resistant Escherichia coli O157:H7 or Salmonella and stored under conditions to simulate food service or consumer handling. The inoculum was grown in broth (for both whole and diced onion experiments) or on agar plates (for whole onion experiments). Marked circles (3.3 cm in diameter) on the outer papery skin of whole onions were spot inoculated (10 μl in 10 drops) at 7 log CFU per circle, and onions were stored at 4°C, 30 to 50 % relative humidity, or at ambient conditions (23°C, 30 to 50 % relative humidity). Diced onions were inoculated at 3 log CFU/g and then stored in open or closed containers at 4°C or ambient conditions. Previously inoculated and ambient-stored diced onions were also mixed 1:9 (wt/wt) with refrigerated uninoculated freshly diced onions and stored in closed containers at ambient conditions. Inoculated pathogens were recovered in 0.1 % peptone and plated onto selective and nonselective media supplemented with 50 μg/ml rifampin. Both E. coli O157:H7 and Salmonella populations declined more rapidly on onion skins when the inoculum was prepared in broth rather than on agar. Agar-prepared E. coli O157:H7 and Salmonella declined by 0.4 and 0.3 log CFU per sample per day, respectively, at ambient conditions; at 4°C the rates of reduction were 0.08 and 0.06 log CFU per sample per day for E. coli O157:H7 and Salmonella, respectively. Populations of E. coli O157:H7 and Salmonella did not change over 6 days of storage at 4°C in diced onions. Lag times of 6 to 9 h were observed with freshly inoculated onion at ambient conditions; no lag was observed when previously inoculated and uninoculated onions were mixed. Growth rates at ambient conditions were 0.2 to 0.3 log CFU/g/h for E. coli O157:H7 and Salmonella in freshly inoculated onion and 0.2 log CFU/g/h in mixed product. Diced onions support pathogen growth and should be kept refrigerated.

The swarming motility of Pseudomonas aeruginosa is blocked by cranberry proanthocyanidins and other tannin-containing materials.

PubMed

O'May, Che; Tufenkji, Nathalie

2011-05-01

Bacterial motility plays a key role in the colonization of surfaces by bacteria and the subsequent formation of resistant communities of bacteria called biofilms. Derivatives of cranberry fruit, predominantly condensed tannins called proanthocyanidins (PACs) have been reported to interfere with bacterial adhesion, but the effects of PACs and other tannins on bacterial motilities remain largely unknown. In this study, we investigated whether cranberry PAC (CPAC) and the hydrolyzable tannin in pomegranate (PG; punicalagin) affected the levels of motilities exhibited by the bacterium Pseudomonas aeruginosa. This bacterium utilizes flagellum-mediated swimming motility to approach a surface, attaches, and then further spreads via the surface-associated motilities designated swarming and twitching, mediated by multiple flagella and type IV pili, respectively. Under the conditions tested, both CPAC and PG completely blocked swarming motility but did not block swimming or twitching motilities. Other cranberry-containing materials and extracts of green tea (also rich in tannins) were also able to block or impair swarming motility. Moreover, swarming bacteria were repelled by filter paper discs impregnated with many tannin-containing materials. Growth experiments demonstrated that the majority of these compounds did not impair bacterial growth. When CPAC- or PG-containing medium was supplemented with surfactant (rhamnolipid), swarming motility was partially restored, suggesting that the effective tannins are in part acting by a rhamnolipid-related mechanism. Further support for this theory was provided by demonstrating that the agar surrounding tannin-induced nonswarming bacteria was considerably less hydrophilic than the agar area surrounding swarming bacteria. This is the first study to show that natural compounds containing tannins are able to block P. aeruginosa swarming motility and that swarming bacteria are repelled by such compounds.

Inhibition of Listeria monocytogenes in Hot Dogs by Surface Application of Freeze-Dried Bacteriocin-Containing Powders from Lactic Acid Bacteria.

PubMed

Ünlü, Gülhan; Nielsen, Barbara; Ionita, Claudia

2016-06-01

Six lactic acid bacteria (LAB) strains, Lactococcus lactis BFE 920, L. lactis subsp. lactis ATCC 11454, L. lactis subsp. cremoris ATCC 14365, Lactobacillus curvatus L442, Lact. curvatus LTH 1174, and Lact. bavaricus MN, were grown in cheddar cheese whey supplemented with complex nutrient sources. Cell-free culture supernatants were freeze-dried, and the resulting bacteriocin-containing powders were applied on the surface of hot dogs that were inoculated (~4 log cfu/hot dog) with a five-strain Listeria monocytogenes cocktail. Hot dogs were vacuum-sealed and stored at 4 °C for 4 weeks. L. monocytogenes was enumerated, using both tryptic soy agar (TSA) and oxford listeria agar (OXA), on day 0 and at 1, 2, 3, and 4 weeks of the refrigerated storage. In hot dogs containing only the L. monocytogenes inoculum, L. monocytogenes counts increased from 4 up to 7 log cfu/hot dog. All samples containing freeze-dried bacteriocin-containing powders exhibited significantly lowered (P < 0.05) L. monocytogenes populations on the surface of hot dogs throughout the 4-week study except for bavaricin MN powder. Bacterial counts on hot dogs packed without any powder were statistically equal on day 0 when enumerated on OXA. Freeze-dried bacteriocin-containing powders from Lact. curvatus L442 and L. lactis subsp. cremoris ATCC 14365 decreased L. monocytogenes populations on the surface of hot dogs by greater than 2 log cfu/hot dog throughout the 4-week study. For the powdered bacteriocin preparations from L. lactis BFE 920, L. lactis subsp. lactis ATCC 11454, and Lact. curvatus LTH 1174, L. monocytogenes populations were determined to be approximately 3-log cfu/hot dog after 4 weeks of storage.

[Determination of in vitro susceptibility of Candida species to amphotericin B by E-test and previously proposed MIC breakpoints on two different media].

PubMed

Alp, Sehnaz; Sancak, Banu; Arikan, Sevtap

2008-04-01

Although much work has concentrated on defining a reliable and reproducible method for determining in vitro susceptibility of Candida species to amphotericin B, there still has been limitations of the proposed techniques. In this study, amphotericin B minimal inhibitory concentrations (MIC) and susceptibility categories of 212 Candida strains (57 C. glabrata, 53 C. lusitaniae, 51 C. krusei and 51 C. tropicalis) were determined by E-test on RPMI agar (RPG) and antibiotic medium 3 agar (AM3) both supplemented with 2% glucose. The results were interpreted according to the proposed MIC breakpoints (> or = 0.38 microg/ml on RPG, >1 microg/ml on AM3) and discrepancies between susceptibility categories were investigated. While all Candida strains included in the study were determined to be susceptible on AM3 by amphotericin B E-test at 48h, 36.3% of the isolates were classified as resistant on RPG at 48 hours. On RPG, C. krusei strains showed the highest resistance rate (94.1% at 48 h), followed by C. tropicalis (35.3% at 48 h) and C. glabrata (17.5% at 48h). At 48h of incubation, 98.1% of C. lusitaniae isolates were found to be susceptible on RPG. The categorical agreement rates between the results obtained on two media and for C. lusitaniae and C. glabrata were 98.1% and 82.5% at 48 hours. For C. tropicalis and C. krusei, the rates of agreement were 64.7% and 5.9% at 48 hours. Conclusively, according to the previously proposed MIC breakpoints for amphotericin B E-test on RPG and AM3, discrepancies between susceptibility categories of Candida species were of remarkable significance.

EVALUATION OF THE TEA TREE OIL ACTIVITY TO ANAEROBIC BACTERIA--IN VITRO STUDY.

PubMed

Ziółkowska-Klinkosz, Marta; Kedzia, Anna; Meissner, Hhenry O; Kedzia, Andrzej W

2016-01-01

The study of the sensitivity to tea tree oil (Australian Company TTD International Pty. Ltd. Sydney) was carried out on 193 strains of anaerobic bacteria isolated from patients with various infections within the oral cavity and respiratory tracts. The susceptibility (MIC) of anaerobes was determined by means of plate dilution technique in Brucella agar supplemented with 5% defibrinated sheep blood, menadione and hemin. Inoculum contained 10(5) CFU per spot was cultured with Steers replicator upon the surface of agar with various tea tree oil concentrations or without oil (anaerobes growth control). Incubation the plates was performed in anaerobic jars under anaerobic conditions at 37 degrees C for 48 h. MIC was defined as the lowest concentrations of the essential oil completely inhibiting growth of anaerobic bacteria. Test results indicate, that among Gram-negative bacteria the most sensitive to essential oil were strains of Veillonella and Porphyromonas species. Essential oil in low concentrations (MIC in the range of = 0.12 - 0.5 mg/mL) inhibited growth of accordingly 80% and 68% strains. The least sensitive were strains of the genus Tannerella, Parabacteroides and Dialister (MIC 1.0 - 2.0 mg/mL). In the case of Gram-positive anaerobic bacteria the tea tree oil was the most active to strains of cocci of the genus Anaerococcus and Ruminococcus (MIC in range = 0.12 - 0.5 mg/mL) or strains of rods of the genus Eubacterium and Eggerthella (MIC = 0.25 mg/mL). Among Gram-positive rods the least sensitive were the strains of the genus Bifidobacterium ( MIC = 2.0 mg/mL). The tea tree oil was more active to Gram-positive than to Gram-negative anaerobic bacteria.

The Swarming Motility of Pseudomonas aeruginosa Is Blocked by Cranberry Proanthocyanidins and Other Tannin-Containing Materials▿

PubMed Central

O'May, Che; Tufenkji, Nathalie

2011-01-01

Bacterial motility plays a key role in the colonization of surfaces by bacteria and the subsequent formation of resistant communities of bacteria called biofilms. Derivatives of cranberry fruit, predominantly condensed tannins called proanthocyanidins (PACs) have been reported to interfere with bacterial adhesion, but the effects of PACs and other tannins on bacterial motilities remain largely unknown. In this study, we investigated whether cranberry PAC (CPAC) and the hydrolyzable tannin in pomegranate (PG; punicalagin) affected the levels of motilities exhibited by the bacterium Pseudomonas aeruginosa. This bacterium utilizes flagellum-mediated swimming motility to approach a surface, attaches, and then further spreads via the surface-associated motilities designated swarming and twitching, mediated by multiple flagella and type IV pili, respectively. Under the conditions tested, both CPAC and PG completely blocked swarming motility but did not block swimming or twitching motilities. Other cranberry-containing materials and extracts of green tea (also rich in tannins) were also able to block or impair swarming motility. Moreover, swarming bacteria were repelled by filter paper discs impregnated with many tannin-containing materials. Growth experiments demonstrated that the majority of these compounds did not impair bacterial growth. When CPAC- or PG-containing medium was supplemented with surfactant (rhamnolipid), swarming motility was partially restored, suggesting that the effective tannins are in part acting by a rhamnolipid-related mechanism. Further support for this theory was provided by demonstrating that the agar surrounding tannin-induced nonswarming bacteria was considerably less hydrophilic than the agar area surrounding swarming bacteria. This is the first study to show that natural compounds containing tannins are able to block P. aeruginosa swarming motility and that swarming bacteria are repelled by such compounds. PMID:21378043

Association of Veterinary Third-Generation Cephalosporin Use with the Risk of Emergence of Extended-Spectrum-Cephalosporin Resistance in Escherichia coli from Dairy Cattle in Japan

PubMed Central

Sato, Toyotaka; Okubo, Torahiko; Usui, Masaru; Yokota, Shin-ichi; Izumiyama, Satoshi; Tamura, Yutaka

2014-01-01

The use of extended-spectrum cephalosporins in food animals has been suggested to increase the risk of spread of Enterobacteriaceae carrying extended-spectrum β-lactamases to humans. However, evidence that selection of extended-spectrum cephalosporin–resistant bacteria owing to the actual veterinary use of these drugs according to criteria established in cattle has not been demonstrated. In this study, we investigated the natural occurrence of cephalosporin-resistant Escherichia coli in dairy cattle following clinical application of ceftiofur. E. coli isolates were obtained from rectal samples of treated and untreated cattle (n = 20/group) cultured on deoxycholate-hydrogen sulfide-lactose agar in the presence or absence of ceftiofur. Eleven cefazoline-resistant isolates were obtained from two of the ceftiofur-treated cattle; no cefazoline-resistant isolates were found in untreated cattle. The cefazoline-resistant isolates had mutations in the chromosomal ampC promoter region and remained susceptible to ceftiofur. Eighteen extended-spectrum cephalosporin–resistant isolates from two ceftiofur-treated cows were obtained on ceftiofur-supplemented agar; no extended-spectrum cephalosporin–resistant isolates were obtained from untreated cattle. These extended-spectrum cephalosporin–resistant isolates possessed plasmid-mediated β-lactamase genes, including bla CTX-M-2 (9 isolates), bla CTX-M-14 (8 isolates), or bla CMY-2 (1 isolate); isolates possessing bla CTX-M-2 and bla CTX-M-14 were clonally related. These genes were located on self-transmissible plasmids. Our results suggest that appropriate veterinary use of ceftiofur did not trigger growth extended-spectrum cephalosporin–resistant E. coli in the bovine rectal flora; however, ceftiofur selection in vitro suggested that additional ceftiofur exposure enhanced selection for specific extended-spectrum cephalosporin–resistant β-lactamase-expressing E. coli clones PMID:24755996

Complex regulation of AprA metalloprotease in Pseudomonas fluorescens M114: evidence for the involvement of iron, the ECF sigma factor, PbrA and pseudobactin M114 siderophore.

PubMed

Maunsell, Bláithín; Adams, Claire; O'Gara, Fergal

2006-01-01

In the soil bacterium Pseudomonas fluorescens M114, extracellular proteolytic activity and fluorescent siderophore (pseudobactin M114) production were previously shown to be co-ordinately negatively regulated in response to environmental iron levels. An iron-starvation extracytoplasmic function sigma factor, PbrA, required for the transcription of siderophore biosynthetic genes, was also implicated in M114 protease regulation. The current study centred on the characterization and genetic regulation of the gene(s) responsible for protease production in M114. A serralysin-type metalloprotease gene, aprA, was identified and found to encode the major, if not only, extracellular protease produced by this strain. The expression of aprA and its protein product were found to be subject to complex regulation. Transcription analysis confirmed that PbrA was required for full aprA transcription under low iron conditions, while the ferric uptake regulator, Fur, was implicated in aprA repression under high iron conditions. Interestingly, the iron regulation of AprA was dependent on culture conditions, with PbrA-independent AprA-mediated proteolytic activity observed on skim milk agar supplemented with yeast extract, when supplied with iron or purified pseudobactin M114. These effects were not observed on skim milk agar without yeast extract. PbrA-independent aprA expression was also observed from a truncated transcriptional fusion when grown in sucrose asparagine tryptone broth supplied with iron or purified pseudobactin M114. Thus, experimental evidence suggested that iron mediated its effects via transcriptional activation by PbrA under low iron conditions, while an as-yet-unidentified sigma factor(s) may be required for the PbrA-independent aprA expression and AprA proteolytic activity induced by siderophore and iron.

Assay for adhesion and agar invasion in S. cerevisiae.

PubMed

Guldal, Cemile G; Broach, James

2006-11-08

Yeasts are found in natural biofilms, where many microorganisms colonize surfaces. In artificial environments, such as surfaces of man-made objects, biofilms can reduce industrial productivity, destroy structures, and threaten human life. 1-3 On the other hand, harnessing the power of biofilms can help clean the environment and generate sustainable energy. 4-8 The ability of S. cerevisiae to colonize surfaces and participate in complex biofilms was mostly ignored until the rediscovery of the differentiation programs triggered by various signaling pathways and environmental cues in this organism. 9, 10 The continuing interest in using S. cerevisiae as a model organism to understand the interaction and convergence of signaling pathways, such as the Ras-PKA, Kss1 MAPK, and Hog1 osmolarity pathways, quickly placed S. cerevisiae in the junction of biofilm biology and signal transduction research. 11-20 To this end, differentiation of yeast cells into long, adhesive, pseudohyphal filaments became a convenient readout for the activation of signal transduction pathways upon various environmental changes. However, filamentation is a complex collection of phenotypes, which makes assaying for it as if it were a simple phenotype misleading. In the past decade, several assays were successfully adopted from bacterial biofilm studies to yeast research, such as MAT formation assays to measure colony spread on soft agar and crystal violet staining to quantitatively measure cell-surface adherence. 12, 21 However, there has been some confusion in assays developed to qualitatively assess the adhesive and invasive phenotypes of yeast in agar. Here, we present a simple and reliable method for assessing the adhesive and invasive quality of yeast strains with easy-to-understand steps to isolate the adhesion assessment from invasion assessment. Our method, adopted from previous studies, 10, 16 involves growing cells in liquid media and plating on differential nutrient conditions for growth of large spots, which we then wash with water to assess adhesion and rub cells completely off the agar surface to assess invasion into the agar. We eliminate the need for streaking cells onto agar, which affects the invasion of cells into the agar. In general, we observed that haploid strains that invade agar are always adhesive, yet not all adhesive strains can invade agar medium. Our approach can be used in conjunction with other assays to carefully dissect the differentiation steps and requirements of yeast signal transduction, differentiation, quorum sensing, and biofilm formation.

Assay for Adhesion and Agar Invasion in S. cerevisiae

PubMed Central

Guldal, Cemile G; Broach, James

2006-01-01

Yeasts are found in natural biofilms, where many microorganisms colonize surfaces. In artificial environments, such as surfaces of man-made objects, biofilms can reduce industrial productivity, destroy structures, and threaten human life. 1-3 On the other hand, harnessing the power of biofilms can help clean the environment and generate sustainable energy. 4-8 The ability of S. cerevisiae to colonize surfaces and participate in complex biofilms was mostly ignored until the rediscovery of the differentiation programs triggered by various signaling pathways and environmental cues in this organism. 9, 10 The continuing interest in using S. cerevisiae as a model organism to understand the interaction and convergence of signaling pathways, such as the Ras-PKA, Kss1 MAPK, and Hog1 osmolarity pathways, quickly placed S. cerevisiae in the junction of biofilm biology and signal transduction research. 11-20 To this end, differentiation of yeast cells into long, adhesive, pseudohyphal filaments became a convenient readout for the activation of signal transduction pathways upon various environmental changes. However, filamentation is a complex collection of phenotypes, which makes assaying for it as if it were a simple phenotype misleading. In the past decade, several assays were successfully adopted from bacterial biofilm studies to yeast research, such as MAT formation assays to measure colony spread on soft agar and crystal violet staining to quantitatively measure cell-surface adherence. 12, 21 However, there has been some confusion in assays developed to qualitatively assess the adhesive and invasive phenotypes of yeast in agar. Here, we present a simple and reliable method for assessing the adhesive and invasive quality of yeast strains with easy-to-understand steps to isolate the adhesion assessment from invasion assessment. Our method, adopted from previous studies, 10, 16 involves growing cells in liquid media and plating on differential nutrient conditions for growth of large spots, which we then wash with water to assess adhesion and rub cells completely off the agar surface to assess invasion into the agar. We eliminate the need for streaking cells onto agar, which affects the invasion of cells into the agar. In general, we observed that haploid strains that invade agar are always adhesive, yet not all adhesive strains can invade agar medium. Our approach can be used in conjunction with other assays to carefully dissect the differentiation steps and requirements of yeast signal transduction, differentiation, quorum sensing, and biofilm formation. PMID:18704175

Detection of Salmonella by indicator agar media and PCR as affected by alfalfa seed homogenates and native bacteria.

PubMed

Liao, C-H; Shollenberger, L M

2003-01-01

To investigate and prevent the undesirable effect of native bacteria and alfalfa seed homogenates on detection of Salmonella in alfalfa seeds by indicator agar media and polymerase chain reaction (PCR). The relative sensitivity of five indicator agar media, including modified semisolid RV (MSRV), xylose-lysine-Tergitol 4 (XLT4), Hektoen enteric agar (HEA), brilliant green agar (BGA) and bismuth sulphite agar (BSA), for detection of Salmonella in the presence of a large number of native bacteria from alfalfa seeds was examined. The detection limit as measured by the ratio between the numbers of native bacteria and Salmonella was estimated to be 10(6) to 1 for MSRV and 10(3) to 1 for XLT4, HEA, BGA or BSA. Presence of alfalfa seed homogenates markedly reduced the sensitivity of Salmonella detection by PCR. The minimal number of Salmonella detectable by PCR was determined to be 1-10 and 100-1000 CFU in the absence and presence of seed homogenate, respectively. Application of anti-Salmonella immunomagnetic beads permitted detection of 2-5 CFU of heat-injured cells in 25 g of seeds within 24 h by PCR. The MSRV medium is more sensitive than other indicator agars for detecting a small number of motile Salmonella in samples containing a large number of native bacteria. Application of immunomagnetic beads eliminates the PCR-inhibitory activity of seed homogenates and improves the detection of Salmonella in inoculated seeds. The results generated from this study will aid the seed distributors, sprout growers and public health officials to identify and recall the Salmonella-contaminated seed lots to be used for sprout production.

Determining the Infectious Dose of Influenza Aerosols in a Mouse Model

DTIC Science & Technology

2012-06-20

the growth of F. tularensis to be relatively slow; incubated at 37 °C it reportedly takes up to 14 days to grow on chocolate agar or cysteine heart...TSB) (BD BBL, Becton Dickinson and Company, Franklin Lakes, NJ), then plated in triplicate on BBL chocolate II agar plates (Lot# S100077/2112/20080806...Laboratories, Philadelphia, PA) and recorded at 580, 600 and 625 nm, and differences before and after aerosolization were noted. Chocolate agar plates

Inactivation of pathogenic bacteria inoculated onto a Bacto™ agar model surface using TiO2-UVC photocatalysis, UVC and chlorine treatments.

PubMed

Yoo, S; Ghafoor, K; Kim, S; Sun, Y W; Kim, J U; Yang, K; Lee, D-U; Shahbaz, H M; Park, J

2015-09-01

The aim of this study was to study inactivation of different pathogenic bacteria on agar model surface using TiO2-UV photocatalysis (TUVP). A unified food surface model was simulated using Bacto(™) agar, a routinely used microbial medium. The foodborne pathogenic bacteria Escherichia coli K12 (as a surrogate for E. coli O157:H7), Salmonella Typhimurium, Staphylococcus aureus and Listeria monocytogenes were inoculated onto the agar surface, followed by investigation of TUVP-assisted inactivation and morphological changes in bacterial cells. The TUVP process showed higher bacterial inactivation, particularly for Gram-negative bacteria, than UVC alone and a control (dark reaction). A TUVP treatment of 17·2 mW cm(-2) (30% lower than the UVC light intensity) reduced the microbial load on the agar surface by 4·5-6·0 log CFU cm(-2). UVC treatment of 23·7 mW cm(-2) caused 3·0-5·3 log CFU cm(-2) reduction. The use of agar model surface is effective for investigation of bacterial disinfection and TUVP is a promising nonthermal technique. The results showing effects of photocatalysis and other treatments for inactivation of bacterial pathogens on model surface can be useful for applying such processes for disinfection of fruit, vegetables and other similar surfaces. © 2015 The Society for Applied Microbiology.

Differential roles of auxin efflux carrier PIN proteins in hypocotyl phototropism of etiolated Arabidopsis seedlings depend on the direction of light stimulus.

PubMed

Haga, Ken; Sakai, Tatsuya

2013-01-01

In a recent study, we demonstrated that although the auxin efflux carrier PIN-FORMED (PIN) proteins, such as PIN3 and PIN7, are required for the pulse-induced first positive phototropism in etiolated Arabidopsis hypocotyls, they are not necessary for the continuous-light-induced second positive phototropism when the seedlings are grown on the surface of agar medium, which causes the hypocotyls to separate from the agar surface. Previous reports have shown that hypocotyl phototropism is slightly impaired in pin3 single mutants when they are grown along the surface of agar medium, where the hypocotyls always contact the agar, producing some friction. To clarify the possible involvement of PIN3 and PIN7 in continuous-light-induced phototropism, we investigated hypocotyl phototropism in the pin3 pin7 double mutant grown along the surface of agar medium. Intriguingly, the phototropic curvature was slightly impaired in the double mutant when the phototropic stimulus was presented on the adaxial side of the hook, but was not impaired when the phototropic stimulus was presented on the abaxial side of the hook. These results indicate that PIN proteins are required for continuous-light-induced second positive phototropism, depending on the direction of the light stimulus, when the seedlings are in contact with agar medium.

Differential roles of auxin efflux carrier PIN proteins in hypocotyl phototropism of etiolated Arabidopsis seedlings depend on the direction of light stimulus

PubMed Central

Haga, Ken; Sakai, Tatsuya

2013-01-01

In a recent study, we demonstrated that although the auxin efflux carrier PIN-FORMED (PIN) proteins, such as PIN3 and PIN7, are required for the pulse-induced first positive phototropism in etiolated Arabidopsis hypocotyls, they are not necessary for the continuous-light-induced second positive phototropism when the seedlings are grown on the surface of agar medium, which causes the hypocotyls to separate from the agar surface. Previous reports have shown that hypocotyl phototropism is slightly impaired in pin3 single mutants when they are grown along the surface of agar medium, where the hypocotyls always contact the agar, producing some friction. To clarify the possible involvement of PIN3 and PIN7 in continuous-light-induced phototropism, we investigated hypocotyl phototropism in the pin3 pin7 double mutant grown along the surface of agar medium. Intriguingly, the phototropic curvature was slightly impaired in the double mutant when the phototropic stimulus was presented on the adaxial side of the hook, but was not impaired when the phototropic stimulus was presented on the abaxial side of the hook. These results indicate that PIN proteins are required for continuous-light-induced second positive phototropism, depending on the direction of the light stimulus, when the seedlings are in contact with agar medium. PMID:23104115

Evaluation of two commercially available chromogenic media for confirmation of methicillin-resistant Staphylococcus aureus from human, animal, and food samples.

PubMed

Ariza-Miguel, Jaime; Oniciuc, Elena-Alexandra; Sanz, Iván; Fernández-Natal, Isabel; Hernández, Marta; Rodríguez-Lázaro, David

2015-09-16

We compared the diagnostic performance of two chromogenic media, Brilliance MRSA 2 agar (Thermo Fisher Scientific) and ChromID MRSA agar (bioMérieux), for MRSA confirmation of 239 Staphylococcus aureus isolates from clinical, animal and food samples. Statistically significant differences were not observed between MRSA confirmation by mecA/mecC PCR, and by culture in both chromogenic media. However, a statistically significant difference was observed between the results obtained by both chromogenic media (p = 0.003). Segregated analysis of the results depending on the origin of the isolates (clinical, animal, and food) revealed a significant lower performance in the MRSA confirmation of food-derived isolates by using Brilliance MRSA 2 agar in comparison to PCR confirmation (p = 0.003) or ChromID MRSA agar (p<0.001). Both chromogenic media provided a good diagnostic performance for detection of MRSA isolates of human and animal origin. In conclusion, the use of chromogenic agar plates for MRSA confirmation of S. aureus isolates can provide a good diagnostic performance (sensitivity >92% and specificity >89%) regardless of the type of chromogenic media used or the origin of the S. aureus isolates. However, our results revealed a lower diagnostic performance for MRSA confirmation of S. aureus isolates from food samples by using Brilliance MRSA 2 agar. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation and characterization of bio-nanocomposite films of agar and silver nanoparticles: laser ablation method.

PubMed

Rhim, Jong-Whan; Wang, Long-Feng; Lee, Yonghoon; Hong, Seok-In

2014-03-15

Silver nanoparticles (AgNPs) were prepared by a laser ablation method and composite films with the AgNPs and agar were prepared by solvent casting method. UV-vis absorbance test and transmission electron microscopy (TEM) analysis results revealed that non-agglomerated spherical AgNPs were formed by the laser ablation method. The surface color of the resulting agar/AgNPs films exhibited the characteristic plasmonic effect of the AgNPs with the maximum absorption peaks of 400-407 nm. X-ray diffraction (XRD) test results also exhibited characteristic AgNPs crystals with diffraction peaks observed at 2θ values of 38.39°, 44.49°, and 64.45°, which were corresponding to (111), (200), and (220) crystallographic planes of face-centered cubic (fcc) silver crystals, respectively. Thermogravimetric analysis (TGA) results showed that thermal stability of the agar/AgNPs composite films was increased by the inclusion of metallic silver. Water vapor barrier properties and surface hydrophobicity of the agar/AgNPs films increased slightly with the increase in AgNPs content but they were not statistically significant (p>0.05), while mechanical strength and stiffness of the composite films decreased slightly (p<0.05). The agar/AgNPs films exhibited distinctive antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli O157:H7) bacterial pathogens. Copyright © 2014 Elsevier Ltd. All rights reserved.

Detection of Small Colony Variants Among Methicillin-Resistant Staphylococcus aureus Blood Isolates.

PubMed

Yagci, Server; Sancak, Banu; Hascelik, Gulsen

2016-12-01

Staphylococcus aureus small colony variants (SCVs) are associated with chronic and persistent infections. Methicillin-resistant S. aureus (MRSA) SCVs cause more severe infections and mortality rates are higher in comparison with infections caused by MRSA. Our objective was to document the prevalence and phenotypical characteristics of SCVs among MRSA blood isolates. MRSA strains isolated from blood during 1999-2009 were evaluated retrospectively. Among 299 MRSA isolates, suspected colonies were inoculated onto Columbia blood agar and Schaedler agar. Columbia blood agar was incubated in normal atmosphere and Schaedler agar in 5-10% CO 2 , both at 35°C. If the small, nonpigmented, nonhemolytic colonies on Columbia blood agar were seen as normal-sized, hemolytic, and pigmented colonies on Schaedler agar, they were considered as MRSA SCVs. Six MRSA SCVs were detected. When subcultures were made, four of them reversed to phenotypically normal S. aureus, but two isolates were stable as SCV phenotype. The prevalence of SCVs among MRSA blood isolates was found as 6/299 (2%) with 2 (0.67%) stable. The detection of SCVs among MRSA blood isolates was reported from Turkey for the first time in this study. As the clinical significance of MRSA infections is well documented, evaluation of MRSA SCVs in clinical samples, especially from intensive care patients and those who have chronic and persistent infections are important to consider.

Biological and physiological characteristics of Neotyphodium gansuense symbiotic with Achnatherum inebrians.

PubMed

Li, Chunjie; Nan, Zhibiao; Li, Fei

2008-01-01

Biological and physiological characteristics of Neotyphodium gansuense were compared with Neotyphodium coenophialum and Epichloë festucae at a range of temperatures and pH values, and on carbon and nitrogen amended media. N. gansuense was able to grow at 10-30 degrees C, but not at 5 degrees C, and slowly at 35 degrees C. The optimal temperature for both N. gansuense and N. coenophialum was 25 degrees C, but that of E. festucae was 20-25 degrees C. The optimal pH ranges for mycelial growth of N. gansuense, N. coenophialum and E. festucae were 5-9, 5-9 and 5-7, respectively. The Neotyphodium and Epichloë endophytes varied in their ability to grow on media containing different carbon and nitrogen nutrients. The preference of N. gansuense for carbon source was sucrose>glucose, lactose, sorbitol, inulin, maltose, mannitol, starch, fructose>xylose. Growth of all three endophytes tested was significantly improved by peptone, tryptone, casein, yeast extract and l-proline. Yeast extract, peptone, casein, tryptone, l-proline, potassium nitrate, ammonium oxalic acid and l-leucine significantly improved growth of N. gansuense. However, ammonium nitrite was not utilized at all by any tested endophyte. N. gansuense grew significantly better on potato dextrose agar (PDA) and oat meal agar (OMA) than on corn meal agar (CMA) and drunken-horse-grass agar (DA), and most slowly on water agar (WA) and saltwater nutrient agar (SNA).

Comparative evaluation of chromogenic agar CM1046 and mFC agar for detection of E. coli and thermotolerant coliform bacteria from water samples.

PubMed

Wohlsen, T D

2011-08-01

The equivalence of Oxoid (CM 1046) Brilliance((TM)) E. coli/coliform selective agar to mFC agar, as used in the Australian/New Zealand Standard Method to detect thermotolerant coliforms and Escherichia coli in water samples, was assessed. A total of 244 water samples were analysed in parallel over a 5-month period. Sewage effluent samples (n = 131, sites = 43), freshwater (n = 62, sites = 18) and marine/brackish water samples (n = 51, sites = 23) were analysed. The Wilcoxon matched-pairs signed-ranks test showed a varying degree of statistical difference between the two methods. All matrices had a higher recovery in the trial method. Enterococci faecalis, Aeromonas spp. and Vibrio spp. did not grow on the CM1046 agar, and Pseudomonas aeruginosa and Enterobacter aerogenes were inhibited. The use of CM 1046 for the detection and enumeration of E. coli and thermotolerant coliforms in water samples is a suitable alternative to the AS/NZS Standard Method. The use of CM1046 agar was less labour intensive and time consuming, as no secondary confirmation steps were required. Confirmed results could be reported within 24 h of sample analysis, as compared to 48 h with the reference method. Public health concerns can be addressed in a more efficient manner. © 2011 Unitywater. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

Molecular genetics of root gravitropism and waving in Arabidopsis thaliana

NASA Technical Reports Server (NTRS)

Sedbrook, J.; Boonsirichai, K.; Chen, R.; Hilson, P.; Pearlman, R.; Rosen, E.; Rutherford, R.; Batiza, A.; Carroll, K.; Schulz, T.;

[Identification of Candida dubliniensis strains using heat tolerance tests, morphological characteristics and molecular methods].

PubMed

Arikan, Sevtap; Darka, Ozge; Hasçelik, Gülşen; Günalp, Ayfer

2003-01-01

Described in 1995, Candida dubliniensis is a novel Candida species closely related to Candida albicans due primarily to its ability to produce germ tube and chlamydospores. Given these phenotypic similarities between the two species, C. dubliniensis cannot be readily distinguished from Candida albicans by routine laboratory work-up. We explored the frequency of isolation of C. dubliniensis among 213 strains previously defined as C. albicans based on their ability to produce germ tube. The test isolates were initially examined for their morphological features on cornmeal tween 80 agar, inability to grow at 45 degrees C, and the biochemical assimilation profile (ID 32C system, bioMerieux, France). Among all, 2 (0.9%) of the isolates were identified as C. dubliniensis based on the production of numerous chlamydospores in chains on cornmeal tween 80 agar and the lack of growth at 45 degrees C. The assimilation profile of these isolates was found to be in accordance with this identification. In an effort to confirm the identification, polymerase chain reaction (PCR) studies were carried out by using the C. dubliniensis specific primer set, DUBF and DUBR. Both of the isolates yielded C. dubliniensis-specific 288 base pair amplification products, confirming the previous identification obtained with the initial screening tests. The isolates were found to be susceptible to fluconazole and itraconazole, and generated amphotericin B minimal inhibitory concentrations of 0.5-1 microgram/ml by NCCLS M27-A2 microdilution method. These data suggest that the isolation rate of C. dubliniensis among our clinical isolates is low. The morphological features on cornmeal tween 80 agar and the lack of ability to grow at 45 degrees C appear as reliable, cheap, and practical screening tests in initial identification of C. dubliniensis among germ tube-producing Candida strains.

Use of bile-esculin agar for rapid differentiation of Enterobacteriaceae.

PubMed Central

Lindell, S S; Quinn, P

1975-01-01

Bile-esculin agar has been used for several years for the presumptive identification of group D streptococci. All members of the Enterobacteriaceae family will also grow on this medium, but only certain ones can hydrolyze esculin to 6,7-dihydroxycoumarin, which reacts with iron to produce a characteristic blackening of the medium. One thousand and six cultures from clinical specimens representing 20 genera were isolated and identified. Heavy inocula from fresh pure culture isolates on heart infusion agar were placed on bile-esculin agar slants and incubated at 35 C. The slants were examined at 4 h and again at 18 h for esculin hydrolysis. Shigella, Salmonella, Arizona, Proteus mirabilis, Proteus morganii, Providencia alcalifaciens, and Providencia stuartii all produced negative results. Klebsiella pneumoniae, Enterobacter aerogenes, Serratia marcescens, and Serratia rubidaea produced a positive reaction in 4 h. The other remaining eight genera exhibited varying results. The use of this medium in conjunction with triple sugar iron-lysine iron agar has been of great value in differentiating the Klebsiella-Enterobacter-Serratia group from other Enterobacteriaceae. PMID:1176613

Induction of curvature in maize roots by calcium or by thigmostimulation: role of the postmitotic isodiametric growth zone

NASA Technical Reports Server (NTRS)

Ishikawa, H.; Evans, M. L.

1992-01-01

We examined the response of primary roots of maize (Zea mays L. cv Merit) to unilateral application of calcium with particular attention to the site of application, the dependence on growth rate, and possible contributions of thigmotropic stimulation during application. Unilateral application of agar to the root cap induced negative curvature whether or not the agar contained calcium. This apparent thigmotropic response was enhanced by including calcium in the agar. Curvature away from objects applied unilaterally to the extreme root tip occurred both in intact and detipped roots. When agar containing calcium chloride was applied to one side of the postmitotic isodiametric growth zone ( a region between the apical meristem and the elongation zone), the root curved toward the side of application. This response could not be induced by plain agar. We conclude that curvature away from calcium applied to the root tip results from a thigmotropic response to stimulation during application. In contrast, curvature toward the calcium applied to the postmitotic isodiametric growth zone results from direct calcium-induced inhibition of growth.

The effect of tigecycline and ertapenem against clinical isolates of Brucella melitensis detected by E-test on different media.

PubMed

Tanyel, E; Coban, A Y; Fisgin, N Tasdelen; Tulek, N

2010-01-01

In this study, in vitro activity of tigecycline (TIG) and ertapenem (ERT) against clinical isolates of Brucella melitensis and the effect of different media on in vitro test results were investigated. The in vitro effects of TIG and ERT to 38 B. melitensis isolates were comparatively investigated in brucella agar and 5% sheep blood agar. MIC value of ERT was 0.032 μg/mL in 23 of 38 and 20 of 38 isolates on blood and brucella agar, respectively. Minimum inhibitory concentration values of TIG were substantially different ranging between 0.064-0.25 μg/mL on blood agar. However, MIC values of TIG were similar on brucella agar with 0.25 μg/mL in 15 of 38 isolates and 0.5 μg/mL in 10 of 38 isolates. In conclusion, although ERT and TIG were effective against B. melitensis isolates in vitro, further studies are needed in order to determine the use of these novel drugs in treatment of brucellosis.

Direct identification and recognition of yeast species from clinical material by using albicans ID and CHROMagar Candida plates.

PubMed

Baumgartner, C; Freydiere, A M; Gille, Y

1996-02-01

Two chromogenic media, Albicans ID and CHROMagar Candida agar plates, were compared with a reference medium, Sabouraud-chloramphenicol agar, and standard methods for the identification of yeast species. This study involved 951 clinical specimens. The detection rates for the two chromogenic media for polymicrobial specimens were 20% higher than that for the Sabouraud-chloramphenicol agar plates. The rates of identification of Candida albicans for Albicans ID and CHROMagar Candida agar plates were, respectively, 37.0 and 6.0% after 24 h of incubation and 93.6 and 92.2% after 72 h of incubation, with specificities of 99.8 and 100%. Furthermore, CHROMagar Candida plates identified 13 of 14 Candida tropicalis and 9 of 12 Candida krusei strains after 48 h of incubation.

27 CFR 24.243 - Filtering aids.

Code of Federal Regulations, 2010 CFR

2010-04-01

... fibers, pulps, earths, or similar materials, may be used as filtering aids in the cellar treatment and finishing of wine. Agar-agar, carrageenan, cellulose, and diatomaceous earth are commonly employed inert...

27 CFR 24.243 - Filtering aids.

Code of Federal Regulations, 2011 CFR

2011-04-01

... fibers, pulps, earths, or similar materials, may be used as filtering aids in the cellar treatment and finishing of wine. Agar-agar, carrageenan, cellulose, and diatomaceous earth are commonly employed inert...

[Analysis of bacterial small-colony variants isolated from clinical specimens].

PubMed

Matsumoto, Takehisa

2014-07-01

There is a slow-growing subpopulation of bacteria with distinctive phenotypic and pathogenic traits called bacterial small-colony variants (SCVs). Phenotypically, SCVs show a slow growth rate, atypical colony morphology, and unusual biochemical characteristics. SCV strains often grow on blood agar or Drigalski agar as non-pigmented or pinpoint pigmented colonies, and key biochemical tests for them are often non-reactive. This review describes analyses of hemin-dependent Escherichia coli SCV and Staphylococcus aureus thymidine-dependent SCVs based on our case reports. Because SCVs exhibit fastidious growth characteristics, clinical microbiologists may easily miss or misidentify them in the clinical laboratory. Therefore, we must elucidate the cause of SCVs, and improve laboratory methods for the identification and assessment of the susceptibility of SCVs in the clinical laboratory.

A study of tablet dissolution by magnetic resonance electric current density imaging.

PubMed

Mikac, Ursa; Demsar, Alojz; Demsar, Franci; Sersa, Igor

2007-03-01

The electric current density imaging technique (CDI) was used to monitor the dissolution of ion releasing tablets (made of various carboxylic acids and of sodium chloride) by following conductivity changes in an agar-agar gel surrounding the tablet. Conductivity changes in the sample were used to calculate spatial and temporal changes of ionic concentrations in the sample. The experimental data for ion migration were compared to a mathematical model based on a solution of the diffusion equation with moving boundary conditions for the tablet geometry. Diffusion constants for different acids were determined by fitting the model to the experimental data. The experiments with dissolving tablets were used to demonstrate the potential of the CDI technique for measurement of ion concentration in the vicinity of ion releasing samples.

Comparison and Recovery of Escherichia coli and Thermotolerant Coliforms in Water with a Chromogenic Medium Incubated at 41 and 44.5°C

PubMed Central

Alonso, Jose L.; Soriano, Adela; Carbajo, Oscar; Amoros, Inmaculada; Garelick, Hemda

1999-01-01

This study compared the performance of a commercial chromogenic medium, CHROMagarECC (CECC), and CECC supplemented with sodium pyruvate (CECCP) with the membrane filtration lauryl sulfate-based medium (mLSA) for enumeration of Escherichia coli and non-E. coli thermotolerant coliforms (KEC). To establish that we could recover the maximum KEC and E. coli population, we compared two incubation temperature regimens, 41 and 44.5°C. Statistical analysis by the Fisher test of data did not demonstrate any statistically significant differences (P = 0.05) in the enumeration of E. coli for the different media (CECC and CECCP) and incubation temperatures. Variance analysis of data performed on KEC counts showed significant differences (P = 0.01) between KEC counts at 41 and 44.5°C on both CECC and CECCP. Analysis of variance demonstrated statistically significant differences (P = 0.05) in the enumeration of total thermotolerant coliforms (TTCs) on CECC and CECCP compared with mLSA. Target colonies were confirmed to be E. coli at a rate of 91.5% and KEC of likely fecal origin at a rate of 77.4% when using CECCP incubated at 41°C. The results of this study showed that CECCP agar incubated at 41°C is efficient for the simultaneous enumeration of E. coli and KEC from river and marine waters. PMID:10427079

Evaluation of VIDAS UP Listeria assay (LPT) for the detection of Listeria in a variety of foods and environmental surfaces: First Action 2013.10.

PubMed

Crowley, Erin; Bird, Patrick; Flannery, Jonathan; Benzinger, M Joseph; Fisher, Kiel; Boyle, Megan; Huffman, Travis; Bastin, Ben; Bedinghaus, Paige; Judd, William; Hoang, Thao; Agin, James; Goins, David; Johnson, Ronald L

2014-01-01

The VIDAS UP Listeria (LPT) is an automated rapid screening enzyme phage-ligand based assay for the detection of Listeria species in human food products and environmental samples. The VIDAS LPT method was compared in a multi-laboratory collaborative study to AOAC Official Method 993.12 Listeria monocytogenes in Milk and Dairy Products reference method following current AOAC guidelines. A total of 14 laboratories participated, representing government and industry, throughout the United States. One matrix, queso fresco (soft Mexican cheese), was analyzed using two different test portion sizes, 25 and 125 g. Samples representing each test portion size were artificially contaminated with Listeria species at three levels, an uninoculated control level [0 colony-forming units (CFU)/test portion], a low-inoculum level (0.2-2 CFU/test portion), and a high-inoculum level (2-5 CFU/test portion). For this evaluation, 1800 unpaired replicate test portions were analyzed by either the VIDAS LPT or AOAC 993.12. Each inoculation level was analyzed using the Probability of Detection (POD) statistical model. For the low-level inoculated test portions, difference in collaborator POD (dLPOD) values of 0.01, (-0.10, 0.13), with 95% confidence intervals, were obtained for both 25 and 125 g test portions. The range of the confidence intervals for dLPOD values for both the 25 and 125 g test portions contains the point 0.0 indicating no statistically significant difference in the number of positive samples detected between the VIDAS LPT and the AOAC methods. In addition to Oxford agar, VIDAS LPT test portions were confirmed using Agar Listeria Ottavani and Agosti (ALOA), a proprietary chromogenic agar for the identification and differentiation of L. monocytogenes and Listeria species. No differences were observed between the two selective agars. The VIDAS LPT method, with the optional ALOA agar confirmation method, was adopted as Official First Action status for the detection of Listeria species in a variety of foods and environmental samples.

Development of a Flow Cytometry-Based Method for Rapid Detection of Escherichia coli and Shigella Spp. Using an Oligonucleotide Probe

PubMed Central

Xue, Yong; Wilkes, Jon G.; Moskal, Ted J.; Williams, Anna J.; Cooper, Willie M.; Nayak, Rajesh; Rafii, Fatemeh; Buzatu, Dan A.

2016-01-01

Standard methods to detect Escherichia coli contamination in food use the polymerase chain reaction (PCR) and agar culture plates. These methods require multiple incubation steps and take a long time to results. An improved rapid flow-cytometry based detection method was developed, using a fluorescence-labeled oligonucleotide probe specifically binding a16S rRNA sequence. The method positively detected 51 E. coli isolates as well as 4 Shigella species. All 27 non-E. coli strains tested gave negative results. Comparison of the new genetic assay with a total plate count (TPC) assay and agar plate counting indicated similar sensitivity, agreement between cytometry cell and colony counts. This method can detect a small number of E.coli cells in the presence of large numbers of other bacteria. This method can be used for rapid, economical, and stable detection of E. coli and Shigella contamination in the food industry and other contexts. PMID:26913737

Development of a Flow Cytometry-Based Method for Rapid Detection of Escherichia coli and Shigella Spp. Using an Oligonucleotide Probe.

PubMed

Xue, Yong; Wilkes, Jon G; Moskal, Ted J; Williams, Anna J; Cooper, Willie M; Nayak, Rajesh; Rafii, Fatemeh; Buzatu, Dan A

2016-01-01

Standard methods to detect Escherichia coli contamination in food use the polymerase chain reaction (PCR) and agar culture plates. These methods require multiple incubation steps and take a long time to results. An improved rapid flow-cytometry based detection method was developed, using a fluorescence-labeled oligonucleotide probe specifically binding a16S rRNA sequence. The method positively detected 51 E. coli isolates as well as 4 Shigella species. All 27 non-E. coli strains tested gave negative results. Comparison of the new genetic assay with a total plate count (TPC) assay and agar plate counting indicated similar sensitivity, agreement between cytometry cell and colony counts. This method can detect a small number of E.coli cells in the presence of large numbers of other bacteria. This method can be used for rapid, economical, and stable detection of E. coli and Shigella contamination in the food industry and other contexts.

Multi-Affinity for Growing Rough Interfaces of Bacterial Colonies

NASA Astrophysics Data System (ADS)

Kobayashi, N.; Ozawa, T.; Saito, K.; Yamazaki, Y.; Matsuyama, T.; Matsushita, M.

We have examined whether rough interfaces of bacterial colonies are multi-affine. We have used the bacterial species called textit{Bacillus subtilis}, which has been found to exhibit a variety of colony patterns when varying both the concentration of nutrient and solidity of agar medium. Consequently, we have found that the colony interface on a nutrient-rich, solid agar medium is multi-affine. On the other hand, the colony interface on a nutrient-rich, semi-solid agar medium is self-affine.

Powdered Chitin Agar as a Selective Medium for Enumeration of Actinomycetes in Water and Soil1

PubMed Central

Hsu, S. C.; Lockwood, J. L.

1975-01-01

Agar media made with 0.4% colloidal chitin plus mineral salts and adjusted to pH 8.0 was superior to four other commonly used media for the isolation and enumeration of actinomycetes from water samples. More actinomycetes developed on chitin agar, and the development of bacteria and fungi was suppressed. Frozen and vacuum-dried chitin from aqueous colloidal suspensions was finely divided and gave results comparable to those obtained with media prepared from colloidal suspensions. Images PMID:234719

Comparison of 2 chromogenic media for the detection of extended-spectrum β-lactamase producing Enterobacteriaceae stool carriage in nursing home residents.

PubMed

Blane, Beth; Brodrick, Hayley J; Gouliouris, Theodore; Ambridge, Kirsty E; Kidney, Angela D; Ludden, Catherine M; Limmathurotsakul, Direk; Török, M Estée; Peacock, Sharon J

2016-03-01

ChromID ESBL agar and Brilliance ESBL agar were compared for the isolation of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae from 298 stools. These had comparable sensitivity and selectivity for the 116 positive samples. Pre-enrichment with cefpodoxime and extending incubation to 48 hours after direct plating both significantly increased sensitivity but reduced selectivity of both agars. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

MotPS is the stator-force generator for motility of alkaliphilic Bacillus, and its homologue is a second functional Mot in Bacillus subtilis.

PubMed

Ito, Masahiro; Hicks, David B; Henkin, Tina M; Guffanti, Arthur A; Powers, Benjamin D; Zvi, Lior; Uematsu, Katsuyuki; Krulwich, Terry A

2004-08-01

The stator-force generator that drives Na+-dependent motility in alkaliphilic Bacillus pseudofirmus OF4 is identified here as MotPS, MotAB-like proteins with genes that are downstream of the ccpA gene, which encodes a major regulator of carbon metabolism. B. pseudofirmus OF4 was only motile at pH values above 8. Disruption of motPS resulted in a non-motile phenotype, and motility was restored by transformation with a multicopy plasmid containing the motPS genes. Purified and reconstituted MotPS from B. pseudofirmus OF4 catalysed amiloride analogue-sensitive Na+ translocation. In contrast to B. pseudofirmus, Bacillus subtilis contains both MotAB and MotPS systems. The role of the motPS genes from B. subtilis in several motility-based behaviours was tested in isogenic strains with intact motAB and motPS loci, only one of the two mot systems or neither mot system. B. subtilis MotPS (BsMotPS) supported Na+-stimulated motility, chemotaxis on soft agar surfaces and biofilm formation, especially after selection of an up-motile variant. BsMotPS also supported motility in agar soft plugs immersed in liquid; motility was completely inhibited by an amiloride analogue. BsMotPS did not support surfactin-dependent swarming on higher concentration agar surfaces. These results indicate that BsMotPS contributes to biofilm formation and motility on soft agar, but not to swarming, in laboratory strains of B. subtilis in which MotAB is the dominant stator-force generator. BsMotPS could potentially be dominant for motility in B. subtilis variants that arise in particular niches.

Methicillin-Resistant Staphylococcus aureus: Comparison of Susceptibility Testing Methods and Analysis of mecA-Positive Susceptible Strains

PubMed Central

Sakoulas, George; Gold, Howard S.; Venkataraman, Lata; DeGirolami, Paola C.; Eliopoulos, George M.; Qian, Qinfang

2001-01-01

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for an increasing number of serious nosocomial and community-acquired infections. Phenotypic heterogeneous drug resistance (heteroresistance) to antistaphylococcal beta-lactams affects the results of susceptibility testing. The present study compared the MRSA-Screen latex agglutination test (Denka Seiken Co., Ltd., Tokyo, Japan) for detection of PBP 2a with agar dilution, the VITEK-1 and VITEK-2 systems (bioMérieux, St. Louis, Mo.), and the oxacillin agar screen test for detection of MRSA, with PCR for the mecA gene used as the “gold standard” assay. Analysis of 107 methicillin-susceptible S. aureus (MSSA) isolates and 203 MRSA isolates revealed that the MRSA-Screen latex agglutination test is superior to any single phenotype-based susceptibility testing method, with a sensitivity of 100% and a specificity of 99.1%. Only one isolate that lacked mecA was weakly positive by the MRSA-Screen latex agglutination test. This isolate was phenotypically susceptible to oxacillin and did not contain the mecA gene by Southern blot hybridization. The oxacillin agar screen test, the VITEK-1 system, the VITEK-2 system, and agar dilution showed sensitivities of 99.0, 99.0, 99.5, and 99%, respectively, and specificities of 98.1, 100, 97.2, and 100%, respectively. The differences in sensitivity or specificity were not statistically significant. Oxacillin bactericidal assays showed that mecA- and PBP 2a-positive S. aureus isolates that are susceptible to antistaphylococcal beta-lactams by conventional methods are functionally resistant to oxacillin. We conclude that the accuracy of the MRSA-Screen latex agglutination method for detection of PBP 2a approaches the accuracy of PCR and is more accurate than any susceptibility testing method used alone for the detection of MRSA. PMID:11682512

Effect of post-treatments and concentration of cotton linter cellulose nanocrystals on the properties of agar-based nanocomposite films.

PubMed

Oun, Ahmed A; Rhim, Jong-Whan

2015-12-10

Cellulose nanocrystals (CNCs) were prepared by acid hydrolysis of cotton linter pulp fibers and three different purification methods, i.e., without post purification (CNC1), dialyzed against distilled water (CNC2), and neutralized with NaOH (CNC3), and their effect on film properties was evaluated by preparation of agar/CNCs composite films. All the CNCs were rod in shape with diameter of 15-50 nm and length of 210-480 nm. FTIR result indicated that there was no distinctive differences in the chemical structure between CNCs and cotton linter cellulose fiber. No significant relationship was observed between the sulfate content and crystallinity index of CNCs. The CNC3 showed higher thermal stability than the other type of CNCs due to the less adverse effect on the thermal stability of sulfate groups induced by the neutralization with NaOH. The tensile strength (TS) of agar film increased by 15% with incorporation of 5 wt% of CNC3, on the contrary, it decreased by 10% and 15% with incorporation of CNC1 and CNC2, respectively. Other performance properties of agar/CNCs composite films such as optical and water vapor barrier properties showed that the CNC3 was more effective filler than the other CNCs. In the range of concentration of CNC3 tested (1-10 wt%), inclusion of 5 wt% of CNC3 was the maximum concentration for improving or maintaining film properties of the composite films. The neutralization of acid hydrolyzed cellulose using NaOH was simple and convenient for the preparation of CNC and bionanocomposite films. Copyright © 2015 Elsevier Ltd. All rights reserved.