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Sample records for acidophilus strain np51

  1. Prevention of Mycobacterium avium subsp. paratuberculosis Infection in BALB/c Mice by Feeding Lactobacillus acidophilus Strain NP-51

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The immune responses of 390 BALB/c mice fed the probiotic Lactobacillus acidophilus strain NP51® and infected with Mycobacterium avium subspecies paratuberculosis (MAP) were evaluated in a 6-month trial. Mice were randomized to nine treatment groups fed either viable- or heat-killed NP51 and inocula...

  2. Prevention of Mycobacterium avium subsp. paratuberculosis (MAP) Infection in BALB/c Mice by Feeding Probiotic Lactobacillus acidophilus NP-51

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to examine effects of feeding Lactobacillus acidophilus strain NP51 to mice challenged with Mycobacterium avium subspecies paratuberculosis (MAP). Mice were randomized to ten treatment groups; sentinels, control, heat-killed MAP, viable MAP, heat-killed NP51, viable ...

  3. Prevention of Mycobacterium avium subsp. paratuberculosis (MAP) infection in BALB/c mice by feeding probiotic Lactobacillus acidophilus NP-51

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to examine effects of feeding Lactobacillus acidophilus strain NP51 to mice challenged with Mycobacterium avium subspecies paratuberculosis (MAP). Mice were randomized to ten treatment groups; sentinels, control, heat-killed MAP, viable MAP, heat-killed NP51, viable ...

  4. Prevention of Mycobacterium avium subsp. paratuberculosis (MAP) Infection in Balb/c Mice by Feeding Probiotic Lactobacillus acidophilus NP-51

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to examine effects of feeding Lactobacillus acidophilus strain NP51 to mice challenged with Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne’s disease. We hypothesized that feeding NP51 would increase Th-1 responses and decrease prog...

  5. Prevention of Mycobacterium avium subsp. paratuberculosis (MAP) infection in Balb/c mice by feeding probiotic Lactobacillus acidophilus NP-51

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to examine effects of feeding Lactobacillus acidophilus strain NP51 to mice challenged with Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne’s disease. We hypothesized that feeding NP51 would increase Th-1 responses and decrease prog...

  6. The other way around: probiotic Lactobacillus acidophilus NP51 restrict progression of Mycobacterium avium subspecies paratuberculosis (MAP) infection in Balb/c mice via activiation of CD8 alpha+ immune cell-mediated immunity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to examine the immune-modulating effects of feeding a novel probiotic Lactobacillus acidophilus strain NP51 to specific pathogen-free Balb/c mice challenged with Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne’s disease (JD) in rumi...

  7. The other way around: Probiotic lactobacillus acidophilus NP51 restricts progression of Mycobacterium avium subspecies paratuberculosis (MAP) infection in Balb/c mice through activation of CD8+ T cell-mediated immunity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to examine immune effects of feeding novel probiotic Lactobacillus acidophilus strain NP51 to specific pathogen-free Balb/c mice challenged with Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne’s disease (JD). We hypothesized that fe...

  8. Complete Genome Sequence of Probiotic Strain Lactobacillus acidophilus La-14.

    PubMed

    Stahl, Buffy; Barrangou, Rodolphe

    2013-01-01

    We present the 1,991,830-bp complete genome sequence of Lactobacillus acidophilus strain La-14 (SD-5212). Comparative genomic analysis revealed 99.98% similarity overall to the L. acidophilus NCFM genome. Globally, 111 single nucleotide polymorphisms (SNPs) (95 SNPs, 16 indels) were observed throughout the genome. Also, a 416-bp deletion in the LA14_1146 sugar ABC transporter was identified. PMID:23788546

  9. Draft Genome Sequence of the Probiotic Strain Lactobacillus acidophilus ATCC 4356

    PubMed Central

    Palomino, Maria Mercedes; Allievi, Mariana C.; Fina Martin, Joaquina; Waehner, Pablo M.; Prado Acosta, Mariano; Sanchez Rivas, Carmen

    2015-01-01

    We present the 1,956,699-bp draft genome sequence of Lactobacillus acidophilus strain ATCC 4356. Comparative genomic analysis revealed 99.96% similarity with L. acidophilus NCFM NC_006814.3 and 99.97% with La-14 NC_021181.2 genomes. PMID:25593259

  10. Draft Genome Sequence of the Probiotic Strain Lactobacillus acidophilus ATCC 4356.

    PubMed

    Palomino, Maria Mercedes; Allievi, Mariana C; Fina Martin, Joaquina; Waehner, Pablo M; Prado Acosta, Mariano; Sanchez Rivas, Carmen; Ruzal, Sandra M

    2015-01-01

    We present the 1,956,699-bp draft genome sequence of Lactobacillus acidophilus strain ATCC 4356. Comparative genomic analysis revealed 99.96% similarity with L. acidophilus NCFM NC_006814.3 and 99.97% with La-14 NC_021181.2 genomes. PMID:25593259

  11. Antibacterial effect of the adhering human Lactobacillus acidophilus strain LB.

    PubMed Central

    Coconnier, M H; Liévin, V; Bernet-Camard, M F; Hudault, S; Servin, A L

    1997-01-01

    The spent culture supernatant of the human Lactobacillus acidophilus strain LB produces an antibacterial activity against a wide range of gram-negative and gram-positive pathogens. It decreased the in vitro viability of Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Shigella flexneri, Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Pseudomonas aeruginosa, and Enterobacter spp. In contrast, it did not inhibit lactobacilli and bifidobacteria. The activity was heat stable and relatively sensitive to enzymatic treatments and developed under acidic conditions. The antimicrobial activity was independent of lactic acid production. Activity against S. typhimurium SL1344 infecting human cultured intestinal Caco-2 cells was observed as it was in the conventional C3H/He/oujco mouse model with S. typhimurium C5 infection and oral treatment with the LB spent culture supernatant. PMID:9145867

  12. Antibacterial effect of the adhering human Lactobacillus acidophilus strain LB.

    PubMed

    Coconnier, M H; Liévin, V; Bernet-Camard, M F; Hudault, S; Servin, A L

    1997-05-01

    The spent culture supernatant of the human Lactobacillus acidophilus strain LB produces an antibacterial activity against a wide range of gram-negative and gram-positive pathogens. It decreased the in vitro viability of Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium, Shigella flexneri, Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Pseudomonas aeruginosa, and Enterobacter spp. In contrast, it did not inhibit lactobacilli and bifidobacteria. The activity was heat stable and relatively sensitive to enzymatic treatments and developed under acidic conditions. The antimicrobial activity was independent of lactic acid production. Activity against S. typhimurium SL1344 infecting human cultured intestinal Caco-2 cells was observed as it was in the conventional C3H/He/oujco mouse model with S. typhimurium C5 infection and oral treatment with the LB spent culture supernatant. PMID:9145867

  13. Genotyping by randomly amplified polymorphic DNA of bacteriocin producing Lactobacillus acidophilus strains from Nigeria.

    PubMed

    Alli, John Adeolu; Iwalokun, Bamidele A; Oluwadun, Afolabi; Okonko, Iheanyi Omezuruike

    2015-01-01

    Yogurt and starter culture producers are still searching strains of Lactobacillus acidophilus to produce healthier yogurt with a longer shelf life and better texture, taste, and quality. This study determined the genotyping of bacteriocin producing Lactobacillus acidophilus strains recovered from Nigerian yogurts. Yogurt samples were collected from four different states of South West regions of Nigeria. Isolates were obtained from MRS Medium and biochemically characterized. This was further confirmed by API50CH. The bacteriocin positivity and activity was determined. Genomic characterization of our Lactobacillus acidophilus strains was done with randomly amplified polymorphic DNA-PCR. All yogurt samples containing Lactobacillus acidophilus strains meet the probiotic requirement of ≥10(6) cfu/mL. The gel picture revealed 6 RAPD clonal types of Lactobacillus acidophilus strains with RAPD type C observed to be more common. Significant differences existed in the mean growth inhibition zone (t = -7.32, P < 0.05 for E. coli ATCC; t = -6.19, P < 0.05 for E. coli clinical isolates; t = -6.16, P < 0.05 for Enterobacter sp; t = -11.92, P < 0.05 for Salmonella typhi, t = -1.10, P > 0.05 Staphylococcus aureus). No correlation between the bacteriocin production, activity, and their RAPD clonal division (X(2) = 7.49, P = 0.1610, df = 5). In conclusion, L. acidophilus isolated in Nigeria samples met the probiotic requirements of ≥10(6) cfu/mL and produce bacteriocins with good spectrum of activity. PMID:25153762

  14. [Particular behavior of different Lactobacillus acidophilus strains in petit-suisse cheese].

    PubMed

    Ribeiro, Keila Marques; Pereira, Lucas Campana; Souza, Cínthia Hoch Batista de; Saad, Susana Marta Isay

    2012-12-01

    The objective of this study was to evaluate the physico-chemical and microbiological characteristics of petit-suisse cheeses manufactured with the addition of two Lactobacillus acidophilus strains: LA-14 (potentially probiotic) and La-5 (probiotic culture), using Streptococcus thermophilus TA040 as starter culture. Three cheese-making trials were prepared: Q1 (control: with TA040), Q2 (with TA040 + LA-14), and Q3 (with TA040 + La-5). Parameters analyzed included microbial counts of probiotic, potentially probiotic and starter microorganisms, and physico-chemical parameters (pH and moisture) after 1, 7, 14, 21, and 28 days of storage of the product at 4 +/- 1 degree C. Viable counts of L. acidophilus remained between 7.46 and 7.62 log CFU g(-1) for La-5, and between 6.39 and 6.83 log CFU g(-1) for LA-14. As for the starter, higher populations were observed for Q2 (9.58-9.68 log CFU g(-1)) and Q3 (9.42-9.79 log CFU g(-1)), when compared to Q1, which suggests synergism between L. acidophilus and the starter culture. Moisture and pH values remained stable for cheeses Q1, Q2, and Q3, and no significant differences were detected between cheeses after the first day of storage (p > 0.05). Particular features of both L. acidophilus strains determined different behavior in petit-suisse cheese, and the better adaptation of the La-5 to the product environment was perceptible, since higher populations were observed when compared to LA-14. PMID:24020254

  15. Caenorhabditis elegans immune conditioning with the probiotic bacterium Lactobacillus acidophilus strain NCFM enhances gram-positive immune responses.

    PubMed

    Kim, Younghoon; Mylonakis, Eleftherios

    2012-07-01

    Although the immune response of Caenorhabditis elegans to microbial infections is well established, very little is known about the effects of health-promoting probiotic bacteria on evolutionarily conserved C. elegans host responses. We found that the probiotic Gram-positive bacterium Lactobacillus acidophilus NCFM is not harmful to C. elegans and that L. acidophilus NCFM is unable to colonize the C. elegans intestine. Conditioning with L. acidophilus NCFM significantly decreased the burden of a subsequent Enterococcus faecalis infection in the nematode intestine and prolonged the survival of nematodes exposed to pathogenic strains of E. faecalis and Staphylococcus aureus, including multidrug-resistant (MDR) isolates. Preexposure of nematodes to Bacillus subtilis did not provide any beneficial effects. Importantly, L. acidophilus NCFM activates key immune signaling pathways involved in C. elegans defenses against Gram-positive bacteria, including the p38 mitogen-activated protein kinase pathway (via TIR-1 and PMK-1) and the β-catenin signaling pathway (via BAR-1). Interestingly, conditioning with L. acidophilus NCFM had a minimal effect on Gram-negative infection with Pseudomonas aeruginosa or Salmonella enterica serovar Typhimurium and had no or a negative effect on defense genes associated with Gram-negative pathogens or general stress. In conclusion, we describe a new system for the study of probiotic immune agents and our findings demonstrate that probiotic conditioning with L. acidophilus NCFM modulates specific C. elegans immunity traits. PMID:22585961

  16. Adhesion of human Lactobacillus acidophilus strain LB to human enterocyte-like Caco-2 cells.

    PubMed

    Chauvière, G; Coconnier, M H; Kernéis, S; Fourniat, J; Servin, A L

    1992-08-01

    Twenty-five strains of lactobacilli were tested for their ability to adhere to human enterocyte-like Caco-2 cells in culture. Seven Lactobacillus strains adhered well to the Caco-2 cells, of which three possessed calcium-independent adhesion properties. A high level of calcium-independent adhesion was observed with the human stool isolate Lactobacillus acidophilus strain LB. Scanning electron microscopy revealed that this strain adhered to the apical brush border of the cells. Adhesion increased in parallel with the morphological and functional differentiation of the Caco-2 cells. Two Lactobacillus components were involved in this adhesion. One was protease-resistant and bacterial-surface-associated; the other was heat-stable, extracellular and protease-sensitive. PMID:1527509

  17. Complete genome sequence of the moderately thermophilic mineral-sulfide-oxidizing firmicute Sulfobacillus acidophilus type strain (NALT)

    SciTech Connect

    Anderson, Iain; Chertkov, Olga; Chen, Amy; Saunders, Elizabeth H; Lapidus, Alla L.; Nolan, Matt; Lucas, Susan; Hammon, Nancy; Deshpande, Shweta; Cheng, Jan-Fang; Han, Cliff; Tapia, Roxanne; Goodwin, Lynne A.; Pitluck, Sam; Liolios, Konstantinos; Pagani, Ioanna; Ivanova, N; Mikhailova, Natalia; Pati, Amrita; Palaniappan, Krishna; Land, Miriam L; Pan, Chongle; Rohde, Manfred; Pukall, Rudiger; Goker, Markus; Detter, J. Chris; Woyke, Tanja; Bristow, James; Eisen, Jonathan; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter; Mavromatis, K

    2012-01-01

    Sulfobacillus acidophilus Norris et al. 1996 is a member of the genus Sulfobacillus which comprises five species of the order Clostridiales. Sulfobacillus species are of interest for comparison to other sulfur and iron oxidizers and also have biomining applications. This is the first completed genome sequence of a type strain of the genus Sulfobacillus, and the second published genome of a member of the species S. acidophilus. The genome, which consists of one chromosome and one plasmid with a total size of 3,557,831 bp, harbors 3,626 protein-coding and 69 RNA genes, and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  18. Viable intestinal passage of a canine jejunal commensal strain Lactobacillus acidophilus LAB20 in dogs.

    PubMed

    Tang, Yurui; Saris, Per E J

    2014-10-01

    The strain Lactobacillus acidophilus LAB20 with immunomodulatory properties was previously found dominant in the jejunal chyme of four dogs, and the novel surface layer protein of LAB20 suggested its competitive colonization in canine gut. To evaluate the persistence and survival of LAB20 in healthy dogs, LAB20 was fed to five healthy pet dogs for 3 days, at a dosage of 10(8) CFU daily as fermented milk supplement. The fecal samples, from 1 day prior to feeding, three continuous feeding days, and on day 5, 7, 14, and 21, were collected for strain-specific detection of LAB20 using real-time PCR. We found that LAB20 count was significantly increased in dog fecal samples at the second feeding day, but rapidly decreased after feeding ceased. The fecal samples from prior to feeding, during feeding, and post-cessation days were plated onto mLBS7 agar, from where LAB20 was recovered and distinguishable from other fecal lactobacilli based on its colony morphotype. Using strain-specific PCR detection, the colonies were further verified as LAB20 indicating that LAB20 can survive through the passage of the canine intestine. This study suggested that canine-derived strain LAB20 maintained at high numbers during feeding, viably transited through the dog gut, and could be identified based on its colony morphotype. PMID:24849733

  19. Inhibition of adhesion of enteroinvasive pathogens to human intestinal Caco-2 cells by Lactobacillus acidophilus strain LB decreases bacterial invasion.

    PubMed

    Coconnier, M H; Bernet, M F; Kernéis, S; Chauvière, G; Fourniat, J; Servin, A L

    1993-07-01

    Salmonella typhimurium and enteropathogenic Escherichia coli (EPEC) were found to adhere to the brush border of differentiated human intestinal epithelial Caco-2 cells in culture, whereas Yersinia pseudotuberculosis and Listeria monocytogenes adhered to the periphery of undifferentiated Caco-2 cells. All these enterovirulent strains invaded the Caco-2 cells. Using a heat-killed human Lactobacillus acidophilus (strain LB) which strongly adheres both to undifferentiated and differentiated Caco-2 cells, we have studied inhibition of cell association with and invasion within Caco-2 cells by enterovirulent bacteria. Living and heat-killed Lactobacillus acidophilus strain LB inhibited both cell association and invasion of Caco-2 cells by enterovirulent bacteria in a concentration-dependent manner. The mechanism of inhibition of both adhesion and invasion appears to be due to steric hindrance of human enterocytic pathogen receptors by whole-cell lactobacilli rather than to a specific blockade of receptors. PMID:8354463

  20. Selection of the Strain Lactobacillus acidophilus ATCC 43121 and Its Application to Brewers' Spent Grain Conversion into Lactic Acid

    PubMed Central

    Liguori, Rossana; Soccol, Carlos Ricardo; Vandenberghe, Luciana Porto de Souza; Woiciechowski, Adenise Lorenci; Ionata, Elena; Marcolongo, Loredana; Faraco, Vincenza

    2015-01-01

    Six Lactobacillus strains were analyzed to select a bacterium for conversion of brewers' spent grain (BSG) into lactic acid. Among the investigated strains, L. acidophilus ATCC 43121 showed the highest yield of lactic acid production (16.1 g/L after 48 hours) when grown in a synthetic medium. It was then analyzed for its ability to grow on the hydrolysates obtained from BSG after acid-alkaline (AAT) or aqueous ammonia soaking (AAS) pretreatment. The lactic acid production by L. acidophilus ATCC 43121 through fermentation of the hydrolysate from AAS treated BSG was 96% higher than that from the AAT treated one, although similar yields of lactic acid per consumed glucose were achieved due to a higher (46%) glucose consumption by L. acidophilus ATCC 43121 in the AAS BSG hydrolysate. It is worth noting that adding yeast extract to the BSG hydrolysates increased both the yield of lactic acid per substrate consumed and the volumetric productivity. The best results were obtained by fermentation of AAS BSG hydrolysate supplemented by yeast extract, in which the strain produced 22.16 g/L of lactic acid (yield of 0.61 g/g), 27% higher than the value (17.49 g/L) obtained in the absence of a nitrogen source. PMID:26640784

  1. Complete genome sequence of the moderately thermophilic mineral-sulfide-oxidizing firmicute Sulfobacillus acidophilus type strain (NAL(T)).

    PubMed

    Anderson, Iain; Chertkov, Olga; Chen, Amy; Saunders, Elizabeth; Lapidus, Alla; Nolan, Matt; Lucas, Susan; Hammon, Nancy; Deshpande, Shweta; Cheng, Jan-Fang; Han, Cliff; Tapia, Roxanne; Goodwin, Lynne A; Pitluck, Sam; Liolios, Konstantinos; Pagani, Ioanna; Ivanova, Natalia; Mikhailova, Natalia; Pati, Amrita; Palaniappan, Krishna; Land, Miriam; Pan, Chongle; Rohde, Manfred; Pukall, Rüdiger; Göker, Markus; Detter, John C; Woyke, Tanja; Bristow, James; Eisen, Jonathan A; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C; Klenk, Hans-Peter; Mavromatis, Konstantinos

    2012-07-30

    Sulfobacillus acidophilus Norris et al. 1996 is a member of the genus Sulfobacillus which comprises five species of the order Clostridiales. Sulfobacillus species are of interest for comparison to other sulfur and iron oxidizers and also have biomining applications. This is the first completed genome sequence of a type strain of the genus Sulfobacillus, and the second published genome of a member of the species S. acidophilus. The genome, which consists of one chromosome and one plasmid with a total size of 3,557,831 bp harbors 3,626 protein-coding and 69 RNA genes, and is a part of the GenomicEncyclopedia ofBacteria andArchaea project. PMID:23407703

  2. Application of Lactobacillus acidophilus (LA 5) strain in fruit-based ice cream.

    PubMed

    Senanayake, Suraji A; Fernando, Sirimali; Bamunuarachchi, Arthur; Arsekularatne, Mariam

    2013-11-01

    A study was performed to apply a probiotic strain into fermented ice cream mix with suitable fruit bases to develop a value-added product with a substantial level of viable organisms for a sufficient shelf life. Pure direct vat strain culture of Lactobacillus acidophilus (LA 5) in freeze-dried form was inoculated into a mixture of ice cream, frozen, and the number of viable organisms during frozen storage for a period of time was enumerated, using turbidity measurements with a spectrophotometer. An ice cream sample prepared without the probiotic culture was compared with the test sample for quality, by testing the basic quality parameters for ice cream. Results show a reduction in the over run of the probiotic ice cream compared to the nonprobiotic ice cream. Significantly high level (P < 0.05) of total solids (42%), proteins (16.5%), and titratable acidity (2.2%) was observed in the test sample compared to the nonprobiotic ice cream. Significantly low pH level in the probiotic sample may be due to the lactic acid produced by the probiotic culture. No significant difference (P > 0.05) in the fat content in the two types of ice cream was observed. A significantly low level (P < 0.05) of melting in the probiotic one may have resulted from less over run, than the nonprobiotic sample. Rapid reduction in the viable cells during frozen storage occurred at -18°C and gradual adaptation occurred over the first 4 weeks. At the 10th week, 1.0 × 10(7) numbers of viable organisms were present in 1 g of the probiotic ice cream. Results show the presence of a sufficient number of viable organisms in the product for the 10-week period, which would be beneficial to consumers. PMID:24804052

  3. Derivation of DNA probes for enumeration of a specific strain of Lactobacillus acidophilus in piglet digestive tract samples.

    PubMed Central

    Rodtong, S; Dobbinson, S; Thode-Andersen, S; McConnell, M A; Tannock, G W

    1993-01-01

    Four DNA probes were derived that hybridized specifically to DNA from Lactobacillus acidophilus O. The probes were constructed by randomly cloning lactobacillus DNA in plasmid vector pBR322. Two of the probes (pSR1 and pSR2) were composed of vector and plasmid DNA inserts (3.6 and 1.6 kb, respectively); the others (pSR3 and pSR4) were composed of vector and chromosomally derived inserts (6.9 and 1.4 kb, respectively). The probes were used to enumerate, by colony hybridization, strain O in digestive tract samples collected from piglets inoculated 24 hours previously with a culture of the strain. The probes did not hybridize to DNA from lactobacilli inhabiting the digestive tract of uninoculated piglets. Strain O made up about 10% of the total lactobacillus population of the pars esophagea and about 20% of the population in other digestive tract samples. Images PMID:8285690

  4. The human Lactobacillus acidophilus strain LA1 secretes a nonbacteriocin antibacterial substance(s) active in vitro and in vivo.

    PubMed

    Bernet-Camard, M F; Liévin, V; Brassart, D; Neeser, J R; Servin, A L; Hudault, S

    1997-07-01

    The adhering human Lactobacillus acidophilus strain LA1 inhibits the cell association and cell invasion of enteropathogens in cultured human intestinal Caco-2 cells (M. F. Bernet, D. Brassard, J. R. Neeser, and A. L. Servin, Gut 35:483-489, 1994). Here, we demonstrate that strain LA1 developed its antibacterial activity in conventional or germ-free mouse models orally infected by Salmonella typhimurium. We present evidence that the spent culture supernatant of strain LA1 (LA1-SCS) contained antibacterial components active against S. typhimurium infecting the cultured human intestinal Caco-2 cells. The LA1-SCS antibacterial activity was observed in vitro against a wide range of gram-negative and gram-positive pathogens, such as Staphylococcus aureus, Listeria monocytogenes, S. typhimurium, Shigella flexneri, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterobacter cloacae. By contrast, no activity was observed against species of the normal gut flora, such as lactobacilli and bifidobacteria. The LA1-SCS antibacterial activity was insensitive to proteases and independent of lactic acid production. PMID:9212421

  5. The human Lactobacillus acidophilus strain LA1 secretes a nonbacteriocin antibacterial substance(s) active in vitro and in vivo.

    PubMed Central

    Bernet-Camard, M F; Liévin, V; Brassart, D; Neeser, J R; Servin, A L; Hudault, S

    1997-01-01

    The adhering human Lactobacillus acidophilus strain LA1 inhibits the cell association and cell invasion of enteropathogens in cultured human intestinal Caco-2 cells (M. F. Bernet, D. Brassard, J. R. Neeser, and A. L. Servin, Gut 35:483-489, 1994). Here, we demonstrate that strain LA1 developed its antibacterial activity in conventional or germ-free mouse models orally infected by Salmonella typhimurium. We present evidence that the spent culture supernatant of strain LA1 (LA1-SCS) contained antibacterial components active against S. typhimurium infecting the cultured human intestinal Caco-2 cells. The LA1-SCS antibacterial activity was observed in vitro against a wide range of gram-negative and gram-positive pathogens, such as Staphylococcus aureus, Listeria monocytogenes, S. typhimurium, Shigella flexneri, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterobacter cloacae. By contrast, no activity was observed against species of the normal gut flora, such as lactobacilli and bifidobacteria. The LA1-SCS antibacterial activity was insensitive to proteases and independent of lactic acid production. PMID:9212421

  6. Antagonistic activity against Helicobacter infection in vitro and in vivo by the human Lactobacillus acidophilus strain LB.

    PubMed

    Coconnier, M H; Lievin, V; Hemery, E; Servin, A L

    1998-11-01

    The purpose of the present study was to examine the activity of the human Lactobacillus acidophilus strain LB, which secretes an antibacterial substance(s) against Helicobacter pylori in vitro and in vivo. The spent culture supernatant (SCS) of the strain LB (LB-SCS) dramatically decreased the viability of H. pylori in vitro independent of pH and lactic acid levels. Adhesion of H. pylori to the cultured human mucosecreting HT29-MTX cells decreased in parallel with the viability of H. pylori. In conventional mice, oral treatment with the LB-SCS protected against infection with Helicobacter felis. Indeed, at both 8 and 49 days post-LB-SCS treatment (29 and 70 days postinfection), inhibition of stomach colonization by H. felis was observed, and no evidence of gastric histopathological lesions was found. LB-SCS treatment inhibits the H. pylori urease activity in vitro and in H. pylori that remained associated with the cultured human mucosecreting HT29-MTX cells. Moreover, a decrease in urease activity was detected in the stomach of the mice infected with H. felis and treated with LB-SCS. PMID:9797324

  7. Impairment of swimming motility by antidiarrheic Lactobacillus acidophilus strain LB retards internalization of Salmonella enterica serovar Typhimurium within human enterocyte-like cells.

    PubMed

    Liévin-Le Moal, Vanessa; Amsellem, Raymonde; Servin, Alain L

    2011-10-01

    We report that both culture and the cell-free culture supernatant (CFCS) of Lactobacillus acidophilus strain LB (Lactéol Boucard) have the ability (i) to delay the appearance of Salmonella enterica serovar Typhimurium strain SL1344-induced mobilization of F-actin and, subsequently, (ii) to retard cell entry by S. Typhimurium SL1344. Time-lapse imaging and Western immunoblotting showed that S. Typhimurium SL1344 swimming motility, as represented by cell tracks of various types, was rapidly but temporarily blocked without affecting the expression of FliC flagellar propeller protein. We show that the product(s) secreted by L. acidophilus LB that supports the inhibitory activity is heat stable and of low molecular weight. The product(s) caused rapid depolarization of the S. Typhimurium SL1344 cytoplasmic membrane without affecting bacterial viability. We identified inhibition of swimming motility as a newly discovered mechanism by which the secreted product(s) of L. acidophilus strain LB retards the internalization of the diarrhea-associated pathogen S. enterica serovar Typhimurium within cultured human enterocyte-like cells. PMID:21825295

  8. Draft Genome Sequences of Five Strains of Lactobacillus acidophilus, Strain CIP 76.13T, Isolated from Humans, Strains CIRM-BIA 442 and CIRM-BIA 445, Isolated from Dairy Products, and Strains DSM 20242 and DSM 9126 of Unknown Origin.

    PubMed

    Falentin, Hélène; Cousin, Sylvie; Clermont, Dominique; Creno, Sophie; Ma, Laurence; Chuat, Victoria; Loux, Valentin; Rüdiger, Pukall; Bizet, Chantal; Bouchier, Christiane

    2013-01-01

    Lactobacillus acidophilus is a natural inhabitant of mammalian gastrointestinal systems and is used in dairy and pharmaceutical products. Five draft genome sequences, covering 1,995,790 nucleotides (nt) on average, are divided into 19 to 34 scaffolds covering 1,995 to 2,053 genes. The draft genome sequences were compared to the sequence of the L. acidophilus NCFM dairy strain. PMID:23969059

  9. Bacteriocin production and resistance to drugs are advantageous features for Lactobacillus acidophilus La-14, a potential probiotic strain.

    PubMed

    Todorov, Svetoslav Dimitrov; Furtado, Danielle Nader; Saad, Susana Marta Isay; Gombossy de Melo Franco, Bernadette Dora

    2011-10-01

    L. acidophilus La-14 produces bacteriocin active against L. monocytogenes ScottA (1600 AU/ml) in MRS broth at 30°C or 37°C. The bacteriocin proved inhibitory to different serological types of Listeria spp. Antimicrobial activity was completely lost after treatment of the cell-free supernatant with proteolytic enzymes. Addition of bacteriocin produced by L. acidophilus La-14 to a 3 h-old culture of L. monocytogenes ScottA repressed cell growth in the following 8h. Treatment of stationary phase cells of L. monocytogenes ScottA (107-108 CFU/ml) by the bacteriocin resulted in growth inhibition. Growth of L. acidophilus La-14 was not inhibited by commercial drugs from different generic groups, including nonsteroidal anti-inflammatory drugs (NSAID) containing diclofenac potassium or ibuprofen arginine. Only one non-antibiotic drug tested, Atlansil (an antiarrhythmic agent), had an inhibitory effect on L. acidophilus La-14 with MIC of 2.5 mg/ml. L. acidophilus La-14 was not affected by drugs containing sodium or potassium diclofenac. L. acidophilus La-14 shows a good resistance to several drugs and may be applied in combination for therapeutic use. PMID:22143809

  10. A Lactobacillus acidophilus strain of human gastrointestinal microbiota origin elicits killing of enterovirulent Salmonella enterica Serovar Typhimurium by triggering lethal bacterial membrane damage.

    PubMed

    Coconnier-Polter, Marie-Hélène; Liévin-Le Moal, Vanessa; Servin, Alain L

    2005-10-01

    The human gastrointestinal microbiota produces antagonistic activities against gastrointestinal bacterial pathogens. We undertook a study to investigate the mechanism(s) by which a Lactobacillus acidophilus strain of human microbiota origin antagonizes the gram-negative enteroinvasive pathogen Salmonella enterica serovar Typhimurium. We showed that the cell-free culture supernatant of L. acidophilus strain LB (LB-CFCS) induced the following effects in S. enterica SL1344: (i) a decrease in intracellular ATP that paralleled bacterial death, (ii) the release of lipopolysaccharide, (iii) permeabilization of the bacterial membrane, and (iv) an increase in the sensitivity of Salmonella to the lytic action of sodium dodecyl sulfate. Finally, we showed using two mutant strains of Salmonella, PhoP MS7953s and PmrA JKS1170, that the two-component regulatory systems PhoP-PhoQ and PmrA-PmrB that regulate the mechanisms of resistance to antibacterial agents in Salmonella did not influence the anti-Salmonella effect of LB-CFCS. PMID:16204528

  11. Safety assessment of potential probiotic lactic acid bacterial strains Lactobacillus rhamnosus HN001, Lb. acidophilus HN017, and Bifidobacterium lactis HN019 in BALB/c mice.

    PubMed

    Zhou, J S; Shu, Q; Rutherfurd, K J; Prasad, J; Birtles, M J; Gopal, P K; Gill, H S

    2000-05-25

    The general safety of immune-enhancing lactic acid bacteria (LAB) strains Lactobacillus rhamnosus HN001 (DR20), Lb. acidophilus HN017, and Bifidobacterium lactis HN019 (DR10) was investigated in a feeding trial. Groups of BALB/c mice were orally administered test LAB strains or the commercial reference strain Lb. acidophilus LA-1 at 2.5 x 10(9), 5 x 10(10) or 2.5 x 10(12) colony forming units (CFU)/kg body weight/day for 4 weeks. Throughout this time, their feed intake, water intake, and live body weight were monitored. At the end of the 4 week observation period, samples of blood, liver, spleen, kidney, mesenteric lymph nodes, and gut tissues (ileum, caecum, and colon) were collected to determine: haematological parameters (red blood cell and platelet counts, haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin, and mean corpuscular haemoglobin concentration); differential leukocyte counts; blood biochemistry (plasma total protein, albumin, cholesterol, and glucose); mucosal histology (epithelial cell height, mucosal thickness, and villus height); and bacterial translocation to extra-gut tissues (blood, liver, spleen, kidney and mesenteric lymph nodes). DNA finger printing techniques were used to identify any viable bacterial strains recovered from these tissues. The results demonstrated that 4 weeks consumption of these LAB strains had no adverse effects on animals' general health status, haematology, blood biochemistry, gut mucosal histology parameters, or the incidence of bacterial translocation. A few viable LAB cells were recovered from the tissues of animals in both control and test groups, but DNA fingerprinting did not identify any of these as the inoculated strains. The results obtained in this study suggest that the potentially probiotic LAB strains HN001, HN017, and HN019 are non-toxic for mice and are therefore likely to be safe for human use. PMID:10857928

  12. Impact of colostomy on intestinal microflora and bacterial translocation in young rats fed with heat-killed Lactobacillus acidophilus strain LB.

    PubMed

    Rigon-Zimmer, K; Mullié, C; Tir-Touil-Meddah, A; Buisson, P; Léké, L; Canarelli, J P

    2008-01-01

    A rat animal model of left colostomy was found to significantly impair the growth curve of rats. Assessment of the intestinal flora showed that colostomy mostly affects the cecal but not colonic microflora. Generally, the number of enterococci was increased in both ileum and cecum; cecal lactobacilli also rose, accounting for a promotion of lactic acid bacteria in colostomised rats. No significant differences between colostomised, laparotomised and control rats could be observed for the translocation of intestinal bacteria to internal organs of rats (i.e. spleen, kidneys, lungs or liver), whatever their diet. Heat-killed Lactobacillus acidophilus strain LB administration (dead probiotic bacteria) tended to exhibit a stimulatory effect on bifidobacteria, probably affecting the culture-medium fermentation substances included in the pharmaceutical product. This effect was abolished by laparotomy and colostomy. A trend towards a probiotic-like effect, not susceptible to colostomy, was also witnessed as counts of lactobacilli tended to increase in both cecum and colon of all animals fed with L. acidophilus LB. PMID:18481224

  13. Complete Genome Sequence of Lactobacillus acidophilus FSI4, Isolated from Yogurt

    PubMed Central

    Iartchouk, Oleg; Kozyavkin, Sergei; Karamychev, Valeri

    2015-01-01

    A new Lactobacillus acidophilus strain, FSI4, isolated from yogurt, was isolated and sequenced in our laboratory. Our data, although supportive of previous conclusions regarding the remarkable stability of L. acidophilus species, indicate accumulating mutations in commercial L. acidophilus strains that warrant further study of the effect of damaged genes on the competitiveness of these bacteria in gut microbiota. PMID:25858829

  14. Adhering heat-killed human Lactobacillus acidophilus, strain LB, inhibits the process of pathogenicity of diarrhoeagenic bacteria in cultured human intestinal cells.

    PubMed

    Coconnier, M H; Bernet, M F; Chauvière, G; Servin, A L

    1993-12-01

    Heat-killed L. acidophilus, strain LB, was tested for its ability to adhere in vitro onto human enterocyte-like Caco-2 and muco-secreting HT29-MTX cells in culture. The heat-killed LB bacteria exhibited a high adhesive property. A diffuse pattern of adhesion was observed to the undifferentiated cells, the apical brush border of the enterocytic cells, and to the mucus layer that covered the surface of the mucus-secreting cells. The inhibitory effect of heat-killed LB organisms against the human intestinal Caco-2 cell-adhesion and cell-invasion by a large variety of diarrhoeagenic bacteria was investigated. The following dose-dependent inhibitions were obtained: (i) against the cell-association of enterotoxigenic, diffusely-adhering and enteropathogenic Escherichia coli, Listeria monocytogenes, Yersinia pseudotuberculosis, and Salmonella typhimurium; (ii) against the cell-invasion by enteropathogenic Escherichia coli, Yersinia pseudotuberculosis, Listeria monocytogenes and Salmonella typhimurium. PMID:8188996

  15. The domestication of the probiotic bacterium Lactobacillus acidophilus

    PubMed Central

    Bull, Matthew J.; Jolley, Keith A.; Bray, James E.; Aerts, Maarten; Vandamme, Peter; Maiden, Martin C. J.; Marchesi, Julian R.; Mahenthiralingam, Eshwar

    2014-01-01

    Lactobacillus acidophilus is a Gram-positive lactic acid bacterium that has had widespread historical use in the dairy industry and more recently as a probiotic. Although L. acidophilus has been designated as safe for human consumption, increasing commercial regulation and clinical demands for probiotic validation has resulted in a need to understand its genetic diversity. By drawing on large, well-characterised collections of lactic acid bacteria, we examined L. acidophilus isolates spanning 92 years and including multiple strains in current commercial use. Analysis of the whole genome sequence data set (34 isolate genomes) demonstrated L. acidophilus was a low diversity, monophyletic species with commercial isolates essentially identical at the sequence level. Our results indicate that commercial use has domesticated L. acidophilus with genetically stable, invariant strains being consumed globally by the human population. PMID:25425319

  16. Genetic and functional aspects of linoleate isomerase in Lactobacillus acidophilus.

    PubMed

    Macouzet, Martin; Robert, Normand; Lee, Byong H

    2010-08-01

    While the remarkable health effects of conjugated linoleic acid (CLA) catalyzed from alpha-linoleic acid by the enzyme linoleate isomerase (LI, EC 5.2.1.5) are well recognized, how widely this biochemical activity is present and the mechanisms of its regulation in lactic acid bacteria are unknown. Although certain strains of Lactobacillus acidophilus can enrich CLA in fermented dairy products, it is unknown if other strains share this capacity. Due to its immense economic importance, this work aimed to investigate genetic aspects of CLA production in L. acidophilus for the first time. The genomic DNA from industrial and type strains of L. acidophilus were subjected to PCR and immunoblot analyses using the putative LI gene of L. reuteri ATCC 55739 as probe. The CLA production ability was estimated by gas chromatography of the biomass extracts. The presumptive LI gene from L. acidophilus ATCC 832 was isolated and sequenced. The resulting sequence shared 71% identity with that of L. reuteri and at least 99% with reported sequences from other L. acidophilus strains. All the strains accumulated detectable levels of CLA and tested positive by PCR and immunoblotting. However, no apparent correlation was observed between the yields and the hybridization patterns. The results suggest that LI activity might be common among L. acidophilus and related species and provide a new tool for screening potential CLA producers. PMID:20461509

  17. Characterization of the Lactobacillus casei group and the Lactobacillus acidophilus group by automated ribotyping.

    PubMed

    Ryu, C S; Czajka, J W; Sakamoto, M; Benno, Y

    2001-01-01

    A total of 91 type and reference strains of the Lactobacillus casei group and the L acidophilus group were characterized by the automated ribotyping device Riboprinter microbial characterization system. The L. casei group was divided into five (C1-C5) genotypes by ribotyping. Among them, the strain of L. casei ATCC 334 was clustered to the same genotype group as most of L. paracasei strains and L casei JCM 1134T generated a riboprint pattern that was different from the type strain of L. zeae. These results supported the designation of L. casei ATCC 334 as the neotype strain, but were not consistent with the reclassification of L. casei JCM 1134T as L. zeae. The L. acidophilus group was also divided into 14 (A1-A11, B1-B3) genotypes by ribotyping. L. acidophilus, L. amylovorus, L. crispatus and L. gallinarum generated ribotype patterns that were distinct from the patterns produced by L. gasseri and L. johnsonii. This result confirmed previous data that the L. acidophilus group divided to two major clusters. Five strains of L. acidophilus and two strains of L. gasseri were correctly reidentified by ribotyping. Most strains belonging to the L. casei group and the L. acidophilus group were discriminated at the species level by automated ribotyping. Thus this RiboPrinter system yields rapid, accurate and reproducible genetic information for the identification of many strains. PMID:11386416

  18. ESR spin trapping for characterization of radical formation in Lactobacillus acidophilus NCFM and Listeria innocua.

    PubMed

    Hougaard, Anni B; Arneborg, Nils; Andersen, Mogens L; Skibsted, Leif H

    2013-09-01

    In this study, radicals in pure cultures of Lactobacillus acidophilus NCFM and Listeria innocua were detected in a quantitative way by electron spin resonance spectroscopy using spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) or N-tert-butyl-α-phenylnitrone (PBN). No adverse effect of spin trap addition on viability was observed for any of the bacterial strains. L. acidophilus NCFM had a higher production of radicals than L. innocua when incubated in a growth medium. Furthermore, by using DMPO in a buffer system, the radicals produced by L. acidophilus NCFM could be identified as hydroxyl radicals. The presence of polyethylene glycol, impermeable for bacterial cells, decreased the signal intensity of the ESR spectrum of the DMPO-OH adduct in cultures of L. acidophilus NCFM and indicated quenching of hydroxyl radicals outside the bacteria. This suggests that radical production is an extracellular event for L. acidophilus NCFM. PMID:23811362

  19. Role of transporter proteins in bile tolerance of Lactobacillus acidophilus.

    PubMed

    Pfeiler, Erika A; Klaenhammer, Todd R

    2009-09-01

    Lactobacillus acidophilus NCFM derivatives containing deletion mutations in the transporter genes LBA0552, LBA1429, LBA1446, and LBA1679 exhibited increased sensitivity to bile. These strains showed unique patterns of sensitivity to a variety of inhibitory compounds, as well as differential accumulations of ciprofloxacin and taurocholate. PMID:19633113

  20. Lactobacillus acidophilus ATCC 4356 inhibits biofilm formation by C. albicans and attenuates the experimental candidiasis in Galleria mellonella

    PubMed Central

    Vilela, Simone FG; Barbosa, Júnia O; Rossoni, Rodnei D; Santos, Jéssica D; Prata, Marcia CA; Anbinder, Ana Lia; Jorge, Antonio OC; Junqueira, Juliana C

    2015-01-01

    Probiotic strains of Lactobacillus have been studied for their inhibitory effects on Candida albicans. However, few studies have investigated the effect of these strains on biofilm formation, filamentation and C. albicans infection. The objective of this study was to evaluate the influence of Lactobacillus acidophilus ATCC 4356 on C. albicans ATCC 18804 using in vitro and in vivo models. In vitro analysis evaluated the effects of L. acidophilus on the biofilm formation and on the capacity of C. albicans filamentation. For in vivo study, Galleria mellonella was used as an infection model to evaluate the effects of L. acidophilus on candidiasis by survival analysis, quantification of C. albicans CFU/mL, and histological analysis. The direct effects of L. acidophilus cells on C. albicans, as well as the indirect effects using only a Lactobacillus culture filtrate, were evaluated in both tests. The in vitro results showed that both L. acidophilus cells and filtrate were able to inhibit C. albicans biofilm formation and filamentation. In the in vivo study, injection of L. acidophilus into G. mellonella larvae infected with C. albicans increased the survival of these animals. Furthermore, the number of C. albicans CFU/mL recovered from the larval hemolymph was lower in the group inoculated with L. acidophilus compared to the control group. In conclusion, L. acidophilus ATCC 4356 inhibited in vitro biofilm formation by C. albicans and protected G. mellonella against experimental candidiasis in vivo. PMID:25654408

  1. Screening of Lactobacilli derived from chicken feces and partial characterization of Lactobacillus acidophilus A12 as an animal probiotics.

    PubMed

    Lee, Na-Kyoung; Yun, Cheol-Won; Kim, Seung Wook; Chang, Hyo-Ihl; Kang, Chang-Won; Paik, Hyun-Dong

    2008-02-01

    This study was performed to screen and select Lactobacillus strains from chicken feces for probiotic use in animals. Of these strains, strain A12 had the highest immunostimulatory effect. Therefore, strain A12 was characterized as a potential probiotic. Strain A12 was tentatively identified as Lactobacillus acidophilus A12, using the API 50 CHL kit based on a 99.9% homology. L. acidophilus A12 was highly resistant to artificial gastric juice (pH 2.5) and bile acid (oxgall). Based on results from the API ZYM kit, leucine arylamidase, crystine arylamidase, acid phosphatase, naphthol-AS-BI-phosphohydrolase, alpha-galactosidase, beta- galactosidase, alpha-glucosidase, beta-glucosidase, and N-acetyl-beta- glucosamidase were produced by strain A12. L. acidophilus A12 showed resistance to several antibiotics (nisin, gentamycin, and erythromycin). The amount of interleukin (IL)-1alpha in 20x concentrated supernatant from L. acidophilus A12 was approximately 156 pg/ml. With regard to antioxidant activity, L. acidophilus A12 supernatant showed 60.6% DPPH radical scavenging activity. These results demonstrate the potential use of L. acidophilus A12 as a health-promoting probiotics. PMID:18309281

  2. Effects of yogurt starter cultures on the survival of Lactobacillus acidophilus.

    PubMed

    Ng, Elizabeth W; Yeung, Marie; Tong, Phillip S

    2011-01-31

    Recognized to confer health benefits to consumers, probiotics such as Lactobacillus acidophilus are commonly incorporated into fermented dairy products worldwide; among which yogurt is a popular delivery vehicle. To materialize most of the putative health benefits associated with probiotics, an adequate amount of viable cells must be delivered at the time of consumption. However, the loss in their viabilities during refrigerated storage has been demonstrated previously. This study focused on the effects of yogurt starter cultures on the survival of five strains of L. acidophilus, with emphases on low pH and acid production. Differential survival behavior between L. acidophilus strains was further analyzed. To this end, viable cell counts of L. acidophilus were determined weekly during 4°C storage in various types of yogurts made with Streptococcus thermophilus alone, L. delbrueckii ssp. bulgaricus alone, both species of the starter cultures, or glucono-delta-lactone (GDL). All yogurt types, except for pasteurized yogurts, were co-fermented with L. acidophilus. Yogurt filtrate was analyzed for the presence of any inhibitory substance and for the amount of hydrogen peroxide. Multiplication of L. acidophilus was not affected by the starter cultures as all strains reached high level on day 0 of the storage period. Throughout the 28-day storage period, cell counts of L. acidophilus PIM703 and SBT2062 remained steady (~6 × 10(7)CFU/g) in yogurts made with both starter cultures, whereas those of ATCC 700396 and NCFM were reduced by a maximum of 3 and 4.6 logs, respectively. When starter cultures were replaced by GDL, all strains survived well, suggesting that a low pH was not a critical factor dictating their survival. In addition, the filtrate collected from yogurts made with starter cultures appeared to have higher inhibitory activities against L. acidophilus than that made with GDL. The presence of viable starter cultures was necessary to adversely affect the

  3. Lactobacillus acidophilus binds to MUC3 component of cultured intestinal epithelial cells with highest affinity.

    PubMed

    Das, Jugal Kishore; Mahapatra, Rajani Kanta; Patro, Shubhransu; Goswami, Chandan; Suar, Mrutyunjay

    2016-04-01

    Lactobacillus strains have been shown to adhere to the mucosal components of intestinal epithelial cells. However, established in vitro adhesion assays have several drawbacks in assessing the adhesion of new Lactobacillus strains. The present study aimed to compare the adhesion of four different Lactobacillus strains and select the most adherent microbe, based on in silico approach supported by in vitro results. The mucus-binding proteins in Lactobacillus acidophilus, L. plantarum, L. brevis and L. fermentum were identified and their capacities to interact with intestinal mucin were compared by molecular docking analysis. Lactobacillus acidophilus had the maximal affinity of binding to mucin with predicted free energy of -6.066 kcal mol(-1) Further, in vitro experimental assay of adhesion was performed to validate the in silico results. The adhesion of L. acidophilus to mucous secreting colon epithelial HT-29 MTX cells was highest at 12%, and it formed biofilm with maximum depth (Z = 84 μm). Lactobacillus acidophilus was determined to be the most adherent strain in the study. All the Lactobacillus strains tested in this study, displayed maximum affinity of binding to MUC3 component of mucus as compared to other gastrointestinal mucins. These findings may have importance in the design of probiotics and health care management. PMID:26946538

  4. S layer protein A of Lactobacillus acidophilus NCFM regulates immature dendritic cell and T cell functions.

    PubMed

    Konstantinov, Sergey R; Smidt, Hauke; de Vos, Willem M; Bruijns, Sven C M; Singh, Satwinder Kaur; Valence, Florence; Molle, Daniel; Lortal, Sylvie; Altermann, Eric; Klaenhammer, Todd R; van Kooyk, Yvette

    2008-12-01

    Dendritic cells (DCs) are antigen-presenting cells that play an essential role in mucosal tolerance. They regularly encounter beneficial intestinal bacteria, but the nature of these cellular contacts and the immune responses elicited by the bacteria are not entirely elucidated. Here, we examined the interactions of Lactobacillus acidophilus NCFM and its cell surface compounds with DCs. L. acidophilus NCFM attached to DCs and induced a concentration-dependent production of IL-10, and low IL-12p70. We further demonstrated that the bacterium binds to DC-specific ICAM-3-grabbing nonintegrin (DC-SIGN), a DC- specific receptor. To identify the DC-SIGN ligand present on the bacterium, we took advantage of a generated array of L. acidophilus NCFM mutants. A knockout mutant of L. acidophilus NCFM lacking the surface (S) layer A protein (SlpA) was significantly reduced in binding to DC-SIGN. This mutant incurred a chromosomal inversion leading to dominant expression of a second S layer protein, SlpB. In the SlpB-dominant strain, the nature of the interaction of this bacterium with DCs changed dramatically. Higher concentrations of proinflammatory cytokines such as IL-12p70, TNFalpha, and IL-1beta were produced by DCs interacting with the SlpB-dominant strain compared with the parent NCFM strain. Unlike the SlpA-knockout mutant, T cells primed with L. acidophilus NCFM stimulated DCs produced more IL-4. The SlpA-DC-SIGN interaction was further confirmed as purified SlpA protein ligated directly to the DC-SIGN. In conclusion, the major S layer protein, SlpA, of L. acidophilus NCFM is the first probiotic bacterial DC-SIGN ligand identified that is functionally involved in the modulation of DCs and T cells functions. PMID:19047644

  5. Bacteriocins Produced by L. Fermentum and L. Acidophilus Can Inhibit Cephalosporin Resistant E. Coli.

    PubMed Central

    Riaz, Saba; Kashif Nawaz, Syed; Hasnain, Shahida

    2010-01-01

    Reemerging infections occur due to resistant bacteria. Such infections create restrictions for clinicians and microbiologists in drug selection. Such problems demand new strategies for solution. Use of bacteriocins for this purpose may be fruitful. In the present research work, the inhibitory effects of bactericins on cephalosporin resistant Escherichia coli are used as model system for the control of antibiotic resistant pathogenic bacteria. Cephalosporin resistant Escherichia coli strain was isolated from pus by using conventional methodology. For bacteriocin production, Lactobacilli strains were selected by using selective media. Out of seventy two strains isolated from yogurt, fecal materials of human, chick, parrot and cat, only two strains (strain 45 and strain 52) were found to produce bacteriocins having antimicrobial potential against cephalosporin resistant Escherichia coli. Biochemical characterization showed that strain 45 belonged to group of Lactobacillus fermentum and strain 52 to Lactobacillus acidophilus. Both strains showed maximum growth at 25°C and 35°C respectively. Suitable pH was 5.5 and 6.0 for Lactobacillus fermentum and Lactobacillus acidophilus respectively. Bacteriocins produced by both strains were found stable at 50, 75 and 100°C for 60min. Function of bacteriocin was also not disturbed due to change in pH. These findings suggest that bacteriocin produced by Lactobacillus fermentum and Lactobacillus acidophilus can be used for the infection control of cephalosporin resistant Escherichia coli. PMID:24031540

  6. The inhibitory effect of a Lactobacillus acidophilus derived biosurfactant on biofilm producer Serratia marcescens

    PubMed Central

    Shokouhfard, Maliheh; Kermanshahi, Rouha Kasra; Shahandashti, Roya Vahedi; Feizabadi, Mohammad Mehdi; Teimourian, Shahram

    2015-01-01

    Objective(s): Serratia marcescens is one of the nosocomial pathogen with the ability to form biofilm which is an important feature in the pathogenesis of S. marcescens. The aim of this study was to determine the anti-adhesive properties of a biosurfactant isolated from Lactobacillus acidophilus ATCC 4356, on S. marcescens strains. Materials and Methods: Lactobacillus acidophilus ATCC 4356 was selected as a probiotic strain for biosurfactant production. Anti-adhesive activities was determined by pre-coating and co- incubating methods in 96-well culture plates. Results: The FTIR analysis of derived biosurfactant revealed the composition as protein component. Due to the release of such biosurfactants, L. acidophilus was able to interfere with the adhesion and biofilm formation of the S. marcescens strains. In co-incubation method, this biosurfactant in 2.5 mg/ml concentration showed anti-adhesive activity against all tested strains of S. marcescens (P<0.05). Conclusion: Our results show that the anti-adhesive properties of L. acidophilus biosurfactant has the potential to be used against microorganisms responsible for infections in the urinary, vaginal and gastrointestinal tracts, as well as skin, making it a suitable alternative to conventional antibiotics. PMID:26730335

  7. The protective effect of recombinant FomA-expressing Lactobacillus acidophilus against periodontal infection.

    PubMed

    Ma, Li; Ding, Qinfeng; Feng, Xiping; Li, Fei

    2013-10-01

    A number of studies have shown that the outer membrane protein FomA found in Fusobacterium nucleatum demonstrates great potential as an immune target for combating periodontitis. Lactobacillus acidophilus is a useful antigen delivery vehicle for mucosal immunisation, and previous studies by our group have shown that L. acidophilus acts as a protective factor in periodontal health. In this study, making use of the immunogenicity of FomA and the probiotic properties of L. acidophilus, we constructed a recombinant form of L. acidophilus expressing the FomA protein and detected the FomA-specific IgG in the serum and sIgA in the saliva of mice through oral administration with the recombinant strains. When serum containing FomA-specific antibodies was incubated with the F. nucleatum in vitro, the number of Porphyromonas gingivalis cells that coaggregated with the F. nucleatum cells was significantly reduced. Furthermore, a mouse gum abscess model was successfully generated, and the range of gingival abscesses in the immune mice was relatively limited compared with the control group. The level of IL-1β in the serum and local gum tissues of the immune mice was consistently lower than in the control group. Our findings indicated that oral administration of the recombinant L. acidophilus reduced the risk of periodontal infection with P. gingivalis and F. nucleatum. PMID:23644821

  8. In vitro evaluation of antibacterial activity of an herbal dentifrice against Streptococcus mutans and Lactobacillus acidophilus.

    PubMed

    Vyas, Yogesh Kumar; Bhatnagar, Maheep; Sharma, Kanika

    2008-01-01

    Antibacterial activity of a herbal dentifrice Arodent against Streptococcus mutans and Lactobacillus acidophilus was evaluated using Colgate as standard. Both bacterial strains were isolated from the oral cavity on selective media and identified by standard methods. The antibacterial activity was assayed by cup-well method. The bacterial lawn of facultative anaerobe S. mutans was established between two layers of agar under microaerophilic conditions. Five and a half millimeters and 10 mm zones of inhibition were produced by Arodent against S. mutans and L. acidophilus , respectively, under microaerophilic conditions. On the other hand, the standard dentifrice Colgate produced 5.83 mm and 10.17 mm zones of inhibition against S. mutans and L. acidophilus , respectively, under microaerophilic condition. The results suggest that Arodent is an effective antibacterial herbal dentifrice. PMID:18245920

  9. Development of a Tiered Multilocus Sequence Typing Scheme for Members of the Lactobacillus acidophilus Complex

    PubMed Central

    Ramachandran, Padmini; Lacher, David W.; Pfeiler, Erika A.

    2013-01-01

    Members of the Lactobacillus acidophilus complex are associated with functional foods and dietary supplements because of purported health benefits they impart to the consumer. Many characteristics of these microorganisms are reported to be strain specific. Therefore, proper strain typing is essential for safety assessment and product labeling, and also for monitoring strain integrity for industrial production purposes. Fifty-two strains of the L. acidophilus complex (L. acidophilus, L. amylovorus, L. crispatus, L. gallinarum, L. gasseri, and L. johnsonii) were genotyped using two established methods and compared to a novel multilocus sequence typing (MLST) scheme. PCR restriction fragment length polymorphism (PCR-RFLP) analysis of the hsp60 gene with AluI and TaqI successfully clustered 51 of the 52 strains into the six species examined, but it lacked strain-level discrimination. Random amplified polymorphic DNA PCR (RAPD-PCR) targeting the M13 sequence resulted in highly discriminatory profiles but lacked reproducibility. In this study, an MLST scheme was developed using the conserved housekeeping genes fusA, gpmA, gyrA, gyrB, lepA, pyrG, and recA, which identified 40 sequence types that successfully clustered all of the strains into the six species. Analysis of the observed alleles suggests that nucleotide substitutions within five of the seven MLST loci have reached saturation, a finding that emphasizes the highly diverse nature of the L. acidophilus complex and our unconventional application of a typically intraspecies molecular typing tool. Our MLST results indicate that this method could be useful for characterization and strain discrimination of a multispecies complex, with the potential for taxonomic expansion to a broader collection of Lactobacillus species. PMID:24038697

  10. Development of a tiered multilocus sequence typing scheme for members of the Lactobacillus acidophilus complex.

    PubMed

    Ramachandran, Padmini; Lacher, David W; Pfeiler, Erika A; Elkins, Christopher A

    2013-12-01

    Members of the Lactobacillus acidophilus complex are associated with functional foods and dietary supplements because of purported health benefits they impart to the consumer. Many characteristics of these microorganisms are reported to be strain specific. Therefore, proper strain typing is essential for safety assessment and product labeling, and also for monitoring strain integrity for industrial production purposes. Fifty-two strains of the L. acidophilus complex (L. acidophilus, L. amylovorus, L. crispatus, L. gallinarum, L. gasseri, and L. johnsonii) were genotyped using two established methods and compared to a novel multilocus sequence typing (MLST) scheme. PCR restriction fragment length polymorphism (PCR-RFLP) analysis of the hsp60 gene with AluI and TaqI successfully clustered 51 of the 52 strains into the six species examined, but it lacked strain-level discrimination. Random amplified polymorphic DNA PCR (RAPD-PCR) targeting the M13 sequence resulted in highly discriminatory profiles but lacked reproducibility. In this study, an MLST scheme was developed using the conserved housekeeping genes fusA, gpmA, gyrA, gyrB, lepA, pyrG, and recA, which identified 40 sequence types that successfully clustered all of the strains into the six species. Analysis of the observed alleles suggests that nucleotide substitutions within five of the seven MLST loci have reached saturation, a finding that emphasizes the highly diverse nature of the L. acidophilus complex and our unconventional application of a typically intraspecies molecular typing tool. Our MLST results indicate that this method could be useful for characterization and strain discrimination of a multispecies complex, with the potential for taxonomic expansion to a broader collection of Lactobacillus species. PMID:24038697

  11. Lipoteichoic acid-deficient Lactobacillus acidophilus regulates downstream signals.

    PubMed

    Saber, Rana; Zadeh, Mojgan; Pakanati, Krishna C; Bere, Praveen; Klaenhammer, Todd; Mohamadzadeh, Mansour

    2011-03-01

    The trillions of microbes residing within the intestine induce critical signals that either regulate or stimulate host immunity via their bacterial products. To better understand the immune regulation elicited by lipoteichoic acid (LTA)-deficient Lactobacillus acidophilus NCFM in steady state and induced inflammation, we deleted phosphoglycerol transferase gene, which synthesizes LTA in L. acidophilus NCFM. In vitro and in vivo experiments were conducted in order to compare the immune regulatory properties of the L. acidophilus strain deficient in LTA (NCK2025) with its wild-type parent (NCK56) in C57BL/6, C57BL/6 recombination-activation gene 1-deficient (Rag1 (-/-)) and C57BL/6 Rag1(-/-)IL-10(-/-) mice. We demonstrate that NCK2025 significantly activates the phosphorylation of Erk1/2 but downregulates the phosphorylation of Akt1, cytosolic group IV PLA2 and p38 in mouse dendritic cells. Similarly, mice treated orally with NCK2025 exhibit decreased phosphorylation of inflammatory signals (Akt1, cytosolic group IV PLA2 or P38) but upregulate Erk1/2-phosphorylation in colonic epithelial cells in comparison with mice treated with NCK56. In addition, regulation of pathogenic CD4+ T cell induced colitis by NCK2025 was observed in Rag1 (-/-) but not Rag1(-/-)IL-10 (-/-) mice suggests a critical role of IL-10 that may be tightly regulated by Erk1/2 signaling. These data highlight the immunosuppressive properties of NCK2025 to deliver regulatory signals in innate cells, which results in the mitigation of T-cell-induced colitis in vivo. PMID:21395377

  12. Membrane filter method to study the effects of Lactobacillus acidophilus and Bifidobacterium longum on fecal microbiota.

    PubMed

    Shimizu, Hidenori; Benno, Yoshimi

    2015-11-01

    A large number of commensal bacteria inhabit the intestinal tract, and interbacterial communication among gut microbiota is thought to occur. In order to analyze symbiotic relationships between probiotic strains and the gut microbiota, a ring with a membrane filter fitted to the bottom was used for in vitro investigations. Test strains comprising probiotic nitto strains (Lactobacillus acidophilus NT and Bifidobacterium longum NT) and type strains (L. acidophilus JCM1132(T) and B. longum JCM1217(T) ) were obtained from diluted fecal samples using the membrane filter to simulate interbacterial communication. Bifidobacterium spp., Streptococcus pasteurianus, Collinsella aerofaciens, and Clostridium spp. were the most abundant gut bacteria detected before coculture with the test strains. Results of the coculture experiments indicated that the test strains significantly promote the growth of Ruminococcus gnavus, Ruminococcus torques, and Veillonella spp. and inhibit the growth of Sutterella wadsworthensis. Differences in the relative abundances of gut bacterial strains were furthermore observed after coculture of the fecal samples with each test strain. Bifidobacterium spp., which was detected as the dominant strain in the fecal samples, was found to be unaffected by coculture with the test strains. In the present study, interbacterial communication using bacterial metabolites between the test strains and the gut microbiota was demonstrated by the coculture technique. The detailed mechanisms and effects of the complex interbacterial communications that occur among the gut microbiota are, however, still unclear. Further investigation of these relationships by coculture of several fecal samples with probiotic strains is urgently required. PMID:26486646

  13. Effect of Bile Salt Hydrolase Inhibitors on a Bile Salt Hydrolase from Lactobacillus acidophilus.

    PubMed

    Lin, Jun; Negga, Rekek; Zeng, Ximin; Smith, Katie

    2014-01-01

    Bile salt hydrolase (BSH), a widely distributed function of the gut microbiota, has a profound impact on host lipid metabolism and energy harvest. Recent studies suggest that BSH inhibitors are promising alternatives to antibiotic growth promoters (AGP) for enhanced animal growth performance and food safety. Using a high-purity BSH from Lactobacillus salivarius strain, we have identified a panel of BSH inhibitors. However, it is still unknown if these inhibitors also effectively inhibit the function of the BSH enzymes from other bacterial species with different sequence and substrate spectrum. In this study, we performed bioinformatics analysis and determined the inhibitory effect of identified BSH inhibitors on a BSH from L. acidophilus. Although the L. acidophilus BSH is phylogenetically distant from the L. salivarius BSH, sequence analysis and structure modeling indicated the two BSH enzymes contain conserved, catalytically important amino residues and domain. His-tagged recombinant BSH from L. acidophilus was further purified and used to determine inhibitory effect of specific compounds. Previously identified BSH inhibitors also exhibited potent inhibitory effects on the L. acidophilus BSH. In conclusion, this study demonstrated that the BSH from L. salivarius is an ideal candidate for screening BSH inhibitors, the promising alternatives to AGP for enhanced feed efficiency, growth performance and profitability of food animals. PMID:25526498

  14. Functional Analysis of an S-Layer-Associated Fibronectin-Binding Protein in Lactobacillus acidophilus NCFM

    PubMed Central

    Hymes, Jeffrey P.; Johnson, Brant R.; Barrangou, Rodolphe

    2016-01-01

    Bacterial surface layers (S-layers) are crystalline arrays of self-assembling proteinaceous subunits called S-layer proteins (Slps) that comprise the outermost layer of the cell envelope. Many additional proteins that are associated with or embedded within the S-layer have been identified in Lactobacillus acidophilus NCFM, an S-layer-forming bacterium that is widely used in fermented dairy products and probiotic supplements. One putative S-layer-associated protein (SLAP), LBA0191, was predicted to mediate adhesion to fibronectin based on the in silico detection of a fibronectin-binding domain. Fibronectin is a major component of the extracellular matrix (ECM) of intestinal epithelial cells. Adhesion to intestinal epithelial cells is considered an important trait for probiotic microorganisms during transit and potential association with the intestinal mucosa. To investigate the functional role of LBA0191 (designated FbpB) in L. acidophilus NCFM, an fbpB-deficient strain was constructed. The L. acidophilus mutant with a deletion of fbpB lost the ability to adhere to mucin and fibronectin in vitro. Homologues of fbpB were identified in five additional putative S-layer-forming species, but no homologues were detected in species outside the L. acidophilus homology group. PMID:26921419

  15. Aglycone Isoflavones and Exopolysaccharides Produced by Lactobacillus acidophilus in Fermented Soybean Paste.

    PubMed

    Kim, Jin-Sun; Lee, Je-Hyuk; Surh, Jeonghee; Kang, Soon Ah; Jang, Ki-Hyo

    2016-06-01

    Bioconversion of aglycone-formed isoflavones from glycoside-formed isoflavones by commercial lactic acid bacteria in fermented soybean paste was evaluated. Enterococcus faecium KCTC 13410 showed the most resistant capacity and Lactobacillus acidophilus KCTC 3925 had a sensitive susceptibility at a high NaCl concentration (13.2%) in fermented soybean paste. Among the 5 strains tested, Lac. acidophilus KCTC 3925 showed the highest relative ratio of aglycone-formed isoflavones to total isoflavones in fermented soybean paste. Production of exopolysaccarides (EPS) by lactic acid bacteria was compared using de Man, Rogosa, and Sharpe medium containing 1% sucrose at 37°C for 48 h. Among the 5 lactic acid bacteria, Lac. acidophilus KCTC 3925 and Lactobacillus rhamnosus KCTC 3929 were investigated to produce EPS. Based on the results concerning growing susceptibility and conversion of aglycone-formed isoflavones/EPS production, it is anticipated that Lac. acidophilus KCTC 3925 may be used for preparation of Cheonggukjang, which contains relative low NaCl content. PMID:27390728

  16. Aglycone Isoflavones and Exopolysaccharides Produced by Lactobacillus acidophilus in Fermented Soybean Paste

    PubMed Central

    Kim, Jin-Sun; Lee, Je-Hyuk; Surh, Jeonghee; Kang, Soon Ah; Jang, Ki-Hyo

    2016-01-01

    Bioconversion of aglycone-formed isoflavones from glycoside-formed isoflavones by commercial lactic acid bacteria in fermented soybean paste was evaluated. Enterococcus faecium KCTC 13410 showed the most resistant capacity and Lactobacillus acidophilus KCTC 3925 had a sensitive susceptibility at a high NaCl concentration (13.2%) in fermented soybean paste. Among the 5 strains tested, Lac. acidophilus KCTC 3925 showed the highest relative ratio of aglycone-formed isoflavones to total isoflavones in fermented soybean paste. Production of exopolysaccarides (EPS) by lactic acid bacteria was compared using de Man, Rogosa, and Sharpe medium containing 1% sucrose at 37°C for 48 h. Among the 5 lactic acid bacteria, Lac. acidophilus KCTC 3925 and Lactobacillus rhamnosus KCTC 3929 were investigated to produce EPS. Based on the results concerning growing susceptibility and conversion of aglycone-formed isoflavones/EPS production, it is anticipated that Lac. acidophilus KCTC 3925 may be used for preparation of Cheonggukjang, which contains relative low NaCl content. PMID:27390728

  17. S-layer production by Lactobacillus acidophilus IBB 801 under environmental stress conditions.

    PubMed

    Grosu-Tudor, Silvia-Simona; Brown, Lucia; Hebert, Elvira M; Brezeanu, Aurelia; Brinzan, Alexandru; Fadda, Silvina; Mozzi, Fernanda; Zamfir, Medana

    2016-05-01

    The ability of microorganisms to synthesize S-layer, the outermost structure of the microbial cell envelope composed of non-covalently bound proteins, has been ascribed to help microorganisms to exert their probiotic properties in the host. In this work, formation of S-layer by the potentially probiotic strain Lactobacillus acidophilus IBB 801 under different stress culture conditions (high incubation temperatures, presence of bile salts or NaCl, and acidic pH) was assayed. A marked S-layer synthesis by L. acidophilus IBB 801 was detected when the strain was grown at 42 °C and in the presence of 0.05 % bile salts or 2.0 % NaCl. The presence of S-layer proteins was further confirmed by transmission electron microscopy and protein identification by MS/MS. The differential expression of the proteome of this strain at 42 °C, when a marked formation of S-layer was detected, revealed the overexpression of six proteins mainly related to general stress and protein biosynthesis and translation, while four proteins detected in lower amounts were involved in DNA repair and energy metabolism. As L. acidophilus IBB 801 produces both a bacteriocin and S-layer proteins, the strain could be of interest to be used in the formulation of functional food products with specific properties. PMID:26910041

  18. The quorum sensing luxS gene is induced in Lactobacillus acidophilus NCFM in response to Listeria monocytogenes.

    PubMed

    Moslehi-Jenabian, Saloomeh; Vogensen, Finn Kvist; Jespersen, Lene

    2011-10-01

    The luxS gene involved in quorum sensing has been shown to control different behaviour of probiotic lactobacilli. In this study we investigated if luxS in Lactobacillus acidophilus NCFM was up-regulated in response to Listeria monocytogenes EGD-e. The two bacterial strains were grown in mono- and co-culture and the growth of both bacteria and the transcriptional level of luxS in L. acidophilus cells were monitored. Contrary to L. acidophilus, the growth of L. monocytogenes was significantly affected by co-cultivation. Transcriptional analysis showed that the expression of luxS increased during exponential growth in L. acidophilus cells with the highest level in the late-exponential growth phase, decreasing in the stationary phase. Following co-cultivation with L. monocytogenes, the transcriptional level of luxS increased significantly in mid-exponential growing cells of L. acidophilus after incubation with viable L. monocytogenes cells and by addition of cell-free culture supernatant of L. monocytogenes, whereas incubation with heat killed cells of L. monocytogenes had no effect on the transcriptional level. This could indicate that the up-regulation of luxS is due to a response to a secreted compound produced by L. monocytogenes cells. PMID:21784546

  19. Lactobacillus acidophilus induces virus immune defence genes in murine dendritic cells by a Toll-like receptor-2-dependent mechanism

    PubMed Central

    Weiss, Gudrun; Rasmussen, Simon; Zeuthen, Louise Hjerrild; Nielsen, Birgit Nøhr; Jarmer, Hanne; Jespersen, Lene; Frøkiær, Hanne

    2010-01-01

    Lactobacilli are probiotics that, among other health-promoting effects, have been ascribed immunostimulating and virus-preventive properties. Certain Lactobacillus spp. have been shown to possess strong interleukin-12 (IL-12) -inducing properties. As IL-12 production depends on the up-regulation of type I interferons (IFNs), we hypothesized that the strong IL-12-inducing capacity of Lactobacillus acidophilus NCFM in murine bone-marrow-derived dendritic cells (DCs) is caused by an up-regulation of IFN-β, which subsequently induces IL-12 and the double-stranded RNA binding Toll-like receptor-3 (TLR-3). The expression of the genes encoding IFN-β, TLR-3, IL-12 and IL-10 in DCs upon stimulation with L. acidophilus NCFM was determined. Lactobacillus acidophilus NCFM induced a much stronger expression of Ifn-β, Il-12 and Il-10 compared with the synthetic double-stranded RNA ligand Poly I:C, whereas the levels of expressed Tlr-3 were similar. Whole genome microarray gene expression analysis revealed that other genes related to viral defence were significantly up-regulated and among the strongest induced genes in DCs stimulated with L. acidophilus NCFM. The ability to induce IFN-β was also detected in another L. acidophilus strain (X37), but was not a property of other probiotic strains tested, i.e. Bifidobacterium bifidum Z9 and Escherichia coli Nissle 1917. The IFN-β expression was markedly reduced in TLR-2−/− DCs, dependent on endocytosis, and the major cause of the induction of Il-12 and Tlr-3 in DCs stimulated with L. acidophilus NCFM. Collectively, our results reveal that certain lactobacilli trigger the expression of viral defence genes in DCs in a TLR-2 manner dependent on IFN-β. PMID:20545783

  20. Lactobacillus acidophilus induces virus immune defence genes in murine dendritic cells by a Toll-like receptor-2-dependent mechanism.

    PubMed

    Weiss, Gudrun; Rasmussen, Simon; Zeuthen, Louise Hjerrild; Nielsen, Birgit Nøhr; Jarmer, Hanne; Jespersen, Lene; Frøkiaer, Hanne

    2010-10-01

    Lactobacilli are probiotics that, among other health-promoting effects, have been ascribed immunostimulating and virus-preventive properties. Certain Lactobacillus spp. have been shown to possess strong interleukin-12 (IL-12) -inducing properties. As IL-12 production depends on the up-regulation of type I interferons (IFNs), we hypothesized that the strong IL-12-inducing capacity of Lactobacillus acidophilus NCFM in murine bone-marrow-derived dendritic cells (DCs) is caused by an up-regulation of IFN-β, which subsequently induces IL-12 and the double-stranded RNA binding Toll-like receptor-3 (TLR-3). The expression of the genes encoding IFN-β, TLR-3, IL-12 and IL-10 in DCs upon stimulation with L. acidophilus NCFM was determined. Lactobacillus acidophilus NCFM induced a much stronger expression of Ifn-β, Il-12 and Il-10 compared with the synthetic double-stranded RNA ligand Poly I:C, whereas the levels of expressed Tlr-3 were similar. Whole genome microarray gene expression analysis revealed that other genes related to viral defence were significantly up-regulated and among the strongest induced genes in DCs stimulated with L. acidophilus NCFM. The ability to induce IFN-β was also detected in another L. acidophilus strain (X37), but was not a property of other probiotic strains tested, i.e. Bifidobacterium bifidum Z9 and Escherichia coli Nissle 1917. The IFN-β expression was markedly reduced in TLR-2(-/-) DCs, dependent on endocytosis, and the major cause of the induction of Il-12 and Tlr-3 in DCs stimulated with L. acidophilus NCFM. Collectively, our results reveal that certain lactobacilli trigger the expression of viral defence genes in DCs in a TLR-2 manner dependent on IFN-β. PMID:20545783

  1. Probiotic Bovamine fine-tunes the ruminal microbiome for enhanced fermentation and immunity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effect of Bovamine, Lactobacillus acidophilus strain NP51 and Propionibacterium freudenreichii strain strain NP24, feeding on the microbial composition of the digestive system microbiota of dairy cattle during late lactation (average DIM = 202 days on time 0). To examine the underly...

  2. Functional analysis of putative adhesion factors in Lactobacillus acidophilus NCFM.

    PubMed

    Buck, B Logan; Altermann, Eric; Svingerud, Tina; Klaenhammer, Todd R

    2005-12-01

    Lactobacilli are major inhabitants of the normal microflora of the gastrointestinal tract, and some select species have been used extensively as probiotic cultures. One potentially important property of these organisms is their ability to interact with epithelial cells in the intestinal tract, which may promote retention and host-bacterial communication. However, the mechanisms by which they attach to intestinal epithelial cells are unknown. The objective of this study was to investigate cell surface proteins in Lactobacillus acidophilus that may promote attachment to intestinal tissues. Using genome sequence data, predicted open reading frames were searched against known protein and protein motif databases to identify four proteins potentially involved in adhesion to epithelial cells. Homologous recombination was used to construct isogenic mutations in genes encoding a mucin-binding protein, a fibronectin-binding protein, a surface layer protein, and two streptococcal R28 homologs. The abilities of the mutants to adhere to intestinal epithelial cells were then evaluated in vitro. Each strain was screened on Caco-2 cells, which differentiate and express markers characteristic of normal small-intestine cells. A significant decrease in adhesion was observed in the fibronectin-binding protein mutant (76%) and the mucin-binding protein mutant (65%). A surface layer protein mutant also showed reduction in adhesion ability (84%), but the effect of this mutation is likely due to the loss of multiple surface proteins that may be embedded in the S-layer. This study demonstrated that multiple cell surface proteins in L. acidophilus NCFM can individually contribute to the organism's ability to attach to intestinal cells in vitro. PMID:16332821

  3. Antibiotic susceptibility of members of the Lactobacillus acidophilus group using broth microdilution and molecular identification of their resistance determinants.

    PubMed

    Mayrhofer, Sigrid; van Hoek, Angela H A M; Mair, Christiane; Huys, Geert; Aarts, Henk J M; Kneifel, Wolfgang; Domig, Konrad J

    2010-11-15

    The range of antibiotic susceptibility to 13 antibiotics in 101 strains of the Lactobacillus acidophilus group was examined using the lactic acid bacteria susceptibility test medium (LSM) and broth microdilution. Additionally, microarray analysis and PCR were applied to identify resistance genes responsible for the displayed resistant phenotypes in a selection of strains. In general, narrow as well as broad unimodal and bimodal MIC distributions were observed for the Lactobacillus acidophilus group and the tested antimicrobial agents. Atypically resistant strains could be determined by visual inspection of the obtained MIC ranges for ampicillin, chloramphenicol, clindamycin, erythromycin, quinupristin/dalfopristin, streptomycin and tetracycline. For most of these atypically resistant strains underlying resistance determinants were found. To our knowledge erm(A) was detected in lactobacilli for the first time within this study. Data derived from this study can be used as a basis for reviewing present microbiological breakpoints for categorization of susceptible and resistant strains within the Lactobacillus acidophilus group to assess the safety of microorganisms intended for use in food and feed applications. PMID:20888656

  4. Evaluation of Helicobacter pylori eradication by triple therapy plus Lactobacillus acidophilus compared to triple therapy alone.

    PubMed

    Medeiros, J A da Silva; Gonçalves, T M F O; Boyanova, L; Pereira, M I de Correia; de Carvalho, J N da Silva Paiva; Pereira, A M de Sousa; Cabrita, A M Silvério

    2011-04-01

    The purpose of this study was to evaluate the influence of adding Lactobacillus acidophilus to a triple regimen for Helicobacter pylori eradication in untreated patients with peptic ulcers or ulcer-scars. This was a pre-randomized, single-blind, interventional, treatment-efficacy study with active controls and parallel-assignment, set in Coimbra, Portugal, on 62 consecutive H. pylori-positive untreated adults with peptic ulcers or ulcer-scars, diagnosed by gastroduodenoscopy, with pre-treatment direct Gram-staining and culture of gastric biopsies. The first 31 patients received esomeprazole 20 mg, amoxicillin 1000 mg and clarithromycin 500 mg (EAC), all b.i.d., for 8 days. The remaining 31 added L. acidophilus, 5 × 10(9) organisms per capsule, 3 + 2 i.d. for 8 days (EACL). The main outcome measure was (13)C urea breath test (UBT), ≥6 weeks after completion of therapy. Successful eradication (UBT-negativity after treatment), was similar in both groups (EAC = 80.6%; EACL = 83.9%, p = 0.740) by both intention-to-treat and per-protocol analysis. The non-eradicated strains were susceptible in vitro to both antibiotics. Adding L. acidophilus to EAC triple therapy did not increase H. pylori eradication rates. Considering the cost and the burden of ingesting five extra capsules daily, supplementing the EAC therapy with L. acidophilus, at this dose, shows no benefit. Further studies with different dosages and duration of treatment, and other probiotics or probiotic combinations are required to improve eradication. PMID:21207091

  5. Effect of exopolysaccharides on the hydrolysis of beta-lactoglobulin by Lactobacillus acidophilus CRL 636 in an in vitro gastric/pancreatic system.

    PubMed

    Pescuma, Micaela; Hébert, Elvira María; Dalgalarrondo, Michèle; Haertlé, Thomas; Mozzi, Fernanda; Chobert, Jean-Marc; Font de Valdez, Graciela

    2009-06-24

    An analysis of the peptides generated by hydrolysis of BLG by nonproliferating cells of the strain Lactobacillus acidophilus CRL 636 was carried out. The effect of polysaccharides (pectin, and two EPS synthesized by two Streptococcus thermophilus strains, EPS1190 and EPS804) on BLG digestibility using an in vitro gastric/pancreatic system was analyzed. Polysaccharides are commonly used in the dairy industry to improve food texture; these hydrocolloids may interact with proteins, affecting their digestibility. Nonproliferating cells of Lb. acidophilus CRL 636 were able to hydrolyze 52% of BLG. Twenty-six resulting peptides with molecular masses in the range 544-4119 Da were identified by LC-MS/MS. These peptides resulted mostly from the hydrolysis of the more accessible N-terminal part of BLG. Degradation of BLG by pepsin was poor (8%). When BLG was previously hydrolyzed by Lb. acidophilus CRL 636, peptic hydrolysis was of 54.8%, while when pectin and EPS1190 were added, hydrolysis was higher (58.2 and 57.2%, respectively). Peptides crossing 8 kDa dialysis membranes after trypsin/chymotrypsin hydrolysis were analyzed by HPSEC. The produced peptides were smaller when BLG was hydrolyzed previously by the Lb. acidophilus strain. Moreover, in the presence of pectin, the amount of the larger peptide (3.5 kDa) observed in the size exclusion chromatograms was considerably decreased. Our studies showed that prehydrolysis of BLG by Lb. acidophilus CRL 636 had a positive influence on BLG digestibility and that polysaccharides may change the peptide profile yielded by trypsin/chymotrypsin hydrolysis, releasing smaller size peptides, which are known to be less immune-reactive. Moreover, Lb. acidophilus CRL 636 was able to hydrolyze the main epitopes (41-60, 102-124, and 149-162) of BLG, reducing its allergenic content. PMID:19469473

  6. Effect of Low Shear Modeled Microgravity (LSMMG) on the Probiotic Lactobacillus Acidophilus ATCC 4356

    NASA Technical Reports Server (NTRS)

    Stahl, S.; Voorhies, A.; Lorenzi, H.; Castro-Wallace, S.; Douglas, G.

    2016-01-01

    The introduction of generally recognized as safe (GRAS) probiotic microbes into the spaceflight food system has the potential for use as a safe, non-invasive, daily countermeasure to crew microbiome and immune dysregulation. However, the microgravity effects on the stress tolerances and genetic expression of probiotic bacteria must be determined to confirm translation of strain benefits and to identify potential for optimization of growth, survival, and strain selection for spaceflight. The work presented here demonstrates the translation of characteristics of a GRAS probiotic bacteria to a microgravity analog environment. Lactobacillus acidophilus ATCC 4356 was grown in the low shear modeled microgravity (LSMMG) orientation and the control orientation in the rotating wall vessel (RWV) to determine the effect of LSMMG on the growth, survival through stress challenge, and gene expression of the strain. No differences were observed between the LSMMG and control grown L. acidophilus, suggesting that the strain will behave similarly in spaceflight and may be expected to confer Earth-based benefits.

  7. Construction and immunogenicity of the recombinant Lactobacillus acidophilus pMG36e-E0-LA-5 of bovine viral diarrhea virus.

    PubMed

    Zhao, Yuelan; Jiang, Lufeng; Liu, Teng; Wang, Min; Cao, Wenbo; Bao, Yongzhan; Qin, Jianhua

    2015-12-01

    Bovine viral diarrhea/mucosal disease (BVD/MD) is an infectious disease of cattle with a worldwide distribution, creating a substantial economic impact. It is caused by bovine viral diarrhea virus (BVDV). This research was conducted to construct the recombinant Lactobacillus acidophilus (L. acidophilus) pMG36e-E0-LA-5 of BVDV E0 gene and to test its immunogenicity and protective efficacy against BVDV infection in the mice model. The BVDV E0 gene was sub-cloned into the expression vector and then transformed into the L. acidophilus LA-5 strain by electroporation. The recombinant L. acidophilus pMG36e-E0-LA-5 was confirmed by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. The mice were immunized orally with the recombinant L. acidophilus pMG36e-E0-LA-5. The serum IgG antibody and fecal sIgA antibody responses, expression levels of interleukin (IL)-12 (IL-12) and interferon gamma (IFN-γ) were detected respectively. On the 7th day after the last-immunization, the mice were inoculated with BVDV to evaluate the protective efficiency of the recombinant L. acidophilus pMG36e-E0-LA-5. The results showed that the expressed products protein E0 in the L. acidophilus LA-5 resulted in single band of 27kDa by SDS-PAGE and its strong reactivity with BVDV antibody was confirmed by Western blotting. The IgG and sIgA antibodies responses, IL-12 and IFN-γ expression levels in the vaccinated mice with recombinant L. acidophilus pMG36e-E0-LA-5 were significantly higher than those in the control mice. The protective rate of the vaccinated mice against BVDV increased significantly, and a 90.00% protection rate in virulent challenge was observed. These results indicated that the recombinant L. acidophilus pMG36e-E0-LA-5 strain was successfully constructed and it could effectively improve the immune response in mice and might provide protection against BVDV. PMID:26386184

  8. Astragalus Root and Elderberry Fruit Extracts Enhance the IFN-β Stimulatory Effects of Lactobacillus acidophilus in Murine-Derived Dendritic Cells

    PubMed Central

    Frøkiær, Hanne; Henningsen, Louise; Metzdorff, Stine Broeng; Weiss, Gudrun; Roller, Marc; Flanagan, John; Fromentin, Emilie; Ibarra, Alvin

    2012-01-01

    Many foods and food components boost the immune system, but little data are available regarding the mechanisms by which they do. Bacterial strains have disparate effects in stimulating the immune system. Indendritic cells, the gram-negative bacteria Escherichia coli upregulates proinflammatory cytokines, whereas gram-positive Lactobacillus acidophilus induces a robust interferon (IFN)-β response. The immune-modulating effects of astragalus root and elderberry fruit extracts were examined in bone marrow-derived murine dendritic cells that were stimulated with L. acidophilus or E. coli. IFN-β and other cytokines were measured by ELISA and RT-PCR. Endocytosis of fluorescence-labeled dextran and L. acidophilus in the presence of elderberry fruit or astragalus root extract was evaluated in dendritic cells. Our results show that both extracts enhanced L. acidophilus-induced IFN-β production and slightly decreased the proinflammatory response to E. coli. The enhanced IFN-β production was associated with upregulation of toll-like receptor 3 and to a varying degree, the cytokines IL-12, IL-6, IL-1β and TNF-α. Both extracts increased endocytosis in immature dendritic cells, and only slightly influenced the viability of the cells. In conclusion, astragalus root and elderberry fruit extracts increase the IFN-β inducing activity of L. acidophilus in dendritic cells, suggesting that they may exert antiviral and immune-enhancing activity. PMID:23118903

  9. Prebiotic Effects of Agave salmiana Fructans in Lactobacillus acidophilus and Bifidobacterium lactis Cultures.

    PubMed

    Castro-Zavala, Adriana; Juárez-Flores, Bertha I; Pinos-Rodríguez, Juan M; Delgado-Portales, Rosa E; Aguirre-Rivera, Juan R; Alcocer-Gouyonnet, Francisco

    2015-11-01

    Agave salmiana is a fructan rich species that is widely distributed in Mexico. The aim of this investigation was to extract the fructans of A. salmiana and evaluate their prebiotic effect in 48 hours in vitro cultures of Bifidobacterium lactis and Lactobacillus acidophilus and to compare this effect with other available fructan sources. A significant difference in pH, optical density and biomass was found in the cultures depending on the source of fructans and the type of bacteria. It was possible to determine a dose-response effect of the A. salmiana fructans and the growth of the studied strains. PMID:26749843

  10. Modification of immune responses and digestive system microbiota of lactating dairy cows by feeding Bovamine(R)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the immune modulatory effects as well as effects on productivity of Bovamine® (Lactobacillus acidophilus strain NP51 and Probionibacterium freudenreichii) fed to Holstein and Jersey dairy cows during late lactation (average DIM = 202.44 days on wk-0). Cows were randomized to treatment g...

  11. Modification of digestive system microbiome of lactating dairy cows by feeding Bovamine: effect on ruminal fermentation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the immune modulatory effects as well as effects on productivity of Bovamine® (Lactobacillus acidophilus strain NP51 and Probionibacterium freudenreichii) on the digestive system microbiome of dairy cattle during late lactation (average DIM = 202). To unveil the underlying mechanisms, ...

  12. Antibacterial activity of Lactobacillus acidophilus and Lactobacillus casei against methicillin-resistant Staphylococcus aureus (MRSA).

    PubMed

    Karska-Wysocki, Barbara; Bazo, Mari; Smoragiewicz, Wanda

    2010-10-20

    Methicillin-resistant Staphylococcus aureus (MRSA) is a multidrug-resistant microorganism and the principal nosocomial pathogen worldwide. The antibacterial activity of lactic acid bacteria against MRSA from ten human clinical isolates as well as MRSA standard strain ATCC 43300 was tested in vitro. The Lactobacillus (Lb.) strains (Lb. acidophilus CL1285(®) and Lb. casei LBC80R) as pure cultures, which came from commercial food products were employed. The growth inhibitory effect produced by the antimicrobial activity of the lactic acid bacteria on the MRSA strains was tested on solid medium using agar diffusion methods as well as a using a liquid medium procedure that contained a mixture of MRSA and lactic acid bacteria cultures. In the latter instance, we were able to demonstrate that the direct interaction of lactic acid bacteria and MRSA in such a mixture led to the elimination of 99% of the MRSA cells after 24 h of their incubation at 37°C. PMID:20116228

  13. Enterotoxigenic intestinal bacteria in tropical sprue. IV. Effect of linoleic acid on growth interrelationships of Lactobacillus acidophilus and Klebsiella pneumoniae.

    PubMed

    Mickelson, M J; Klipstein, F A

    1975-11-01

    The factors responsible for colonization of the small intestine by enterotoxigenic coliform bacteria in Puerto Ricans with tropical sprue are unknown, but epidemiological observations have suggested that they may be related to an increased dietary intake of long-chain unsaturated fatty acids, particularly linoleic acid, which is known to exert an inhibitory effect on the growth of gram-positive organisms that normally comprise the flora of the small intestine. We have examined, by using a glucose-limited continuous-culture system, what effect this fatty acid exerts on the growth relationships of enteric gram-positive and coliform bacteria. In this system, colonization by an invading strain of Klebsiella pneumoniae was prevented by the presence of an established culture of Lactobacillus acidophilus, principally by virtue of a lowered pH of the medium that was incompatible with Klebsiella growth. However, when the population density of L. acidophilus was reduced by the presence of a sufficient concentration of linoleic acid, the invading K. pneumoniae successfully colonized the system and, once established, suppressed the growth of L. acidophilus. These observations indicate that, under the conditions of our chemostat, gram-positive enteric bacteria suppress coliform growth and that this effect is reversible by the presence of linoleic acid. It remains to be established, however, what pertinence these in vitro observations have to conditions within the intestinal tract of persons living in the tropics. PMID:811564

  14. The substitution of a traditional starter culture in mutton fermented sausages by Lactobacillus acidophilus and Bifidobacterium animalis.

    PubMed

    Holko, I; Hrabě, J; Šalaková, A; Rada, V

    2013-07-01

    Common starter cultures used in fermented mutton sausages were substituted by probiotic strains of Lactobacillus acidophilus CCDM 476 and Bifidobacterium animalis 241a. Technological properties of the traditional and the probiotic sausages were compared. The potential probiotic effect was evaluated by enumeration of bifidobacteria and lactobacilli in stool samples of 15 volunteers before and after a 14-day consumption period. The numbers of lactobacilli (10(7) cfu/g) and bifidobacteria (10(3) cfu/g) in the final product did not affect the technological properties. The use of L. acidophilus as a starter culture was found more beneficial than the use of B. animalis. Even after 60 days of storage, high counts of L. acidophilus (10(6) cfu/g) were detected; on the other hand, the counts of B. animalis were under the detection limit. Regarding sensory properties, the probiotic products showed better texture, and, curiously, a reduction of the typical smell of mutton. The numbers of lactobacilli in stool samples increased significantly after the consumption of the probiotic sausages. PMID:23567124

  15. Functional Analysis of an S-Layer-Associated Fibronectin-Binding Protein in Lactobacillus acidophilus NCFM.

    PubMed

    Hymes, Jeffrey P; Johnson, Brant R; Barrangou, Rodolphe; Klaenhammer, Todd R

    2016-05-01

    Bacterial surface layers (S-layers) are crystalline arrays of self-assembling proteinaceous subunits called S-layer proteins (Slps) that comprise the outermost layer of the cell envelope. Many additional proteins that are associated with or embedded within the S-layer have been identified inLactobacillus acidophilusNCFM, an S-layer-forming bacterium that is widely used in fermented dairy products and probiotic supplements. One putative S-layer-associated protein (SLAP), LBA0191, was predicted to mediate adhesion to fibronectin based on thein silicodetection of a fibronectin-binding domain. Fibronectin is a major component of the extracellular matrix (ECM) of intestinal epithelial cells. Adhesion to intestinal epithelial cells is considered an important trait for probiotic microorganisms during transit and potential association with the intestinal mucosa. To investigate the functional role of LBA0191 (designated FbpB) inL. acidophilusNCFM, anfbpB-deficient strain was constructed. TheL. acidophilusmutant with a deletion offbpBlost the ability to adhere to mucin and fibronectinin vitro Homologues offbpBwere identified in five additional putative S-layer-forming species, but no homologues were detected in species outside theL. acidophilushomology group. PMID:26921419

  16. Yield improvement of exopolysaccharides by screening of the Lactobacillus acidophilus ATCC and optimization of the fermentation and extraction conditions

    PubMed Central

    Liu, Qi; Huang, Xingjian; Yang, Dengxiang; Si, Tianlei; Pan, Siyi; Yang, Fang

    2016-01-01

    Exopolysacharides (EPS) produced by Lactobacillus acidophilus play an important role in food processing with its well-recognized antioxidant activity. In this study, a L. acidophilus mutant strain with high-yielding EPS (2.92±0.05 g/L) was screened by chemical mutation (0.2 % diethyl sulfate). Plackett-Burman (PB) design and response surface methodology (RSM) were applied to optimize the EPS fermentation parameters and central composite design (CCD) was used to optimize the EPS extraction parameters. A strain with high-yielding EPS was screened. It was revealed that three parameters (Tween 80, dipotassium hydrogen phosphate and trisodium citrate) had significant influence (P < 0.05) on the EPS yield. The optimal culture conditions for EPS production were: Tween 80 0.6 mL, dipotassium hydrogen phosphate 3.6 g and trisodium citrate 4.1 g (with culture volume of 1 L). In these conditions, the maximum EPS yield was 3.96±0.08 g/L. The optimal extraction conditions analyzed by CCD were: alcohol concentration 70 %, the ratio of material to liquid (M/L ratio) 1:3.6 and the extraction time 31 h. In these conditions, the maximum EPS extraction yield was 1.48±0.23 g/L. It was confirmed by the verification experiments that the EPS yield from L. acidophilus mutant strains reached 5.12±0.73 g/L under the optimized fermentation and extraction conditions, which was 3.8 times higher than that of the control (1.05±0.06 g/L). The results indicated that the strain screening with high-yielding EPS was successful and the optimized fermentation and extraction conditions significantly enhanced EPS yield. It was efficient and industrially promising. PMID:27103893

  17. Yield improvement of exopolysaccharides by screening of the Lactobacillus acidophilus ATCC and optimization of the fermentation and extraction conditions.

    PubMed

    Liu, Qi; Huang, Xingjian; Yang, Dengxiang; Si, Tianlei; Pan, Siyi; Yang, Fang

    2016-01-01

    Exopolysacharides (EPS) produced by Lactobacillus acidophilus play an important role in food processing with its well-recognized antioxidant activity. In this study, a L. acidophilus mutant strain with high-yielding EPS (2.92±0.05 g/L) was screened by chemical mutation (0.2 % diethyl sulfate). Plackett-Burman (PB) design and response surface methodology (RSM) were applied to optimize the EPS fermentation parameters and central composite design (CCD) was used to optimize the EPS extraction parameters. A strain with high-yielding EPS was screened. It was revealed that three parameters (Tween 80, dipotassium hydrogen phosphate and trisodium citrate) had significant influence (P < 0.05) on the EPS yield. The optimal culture conditions for EPS production were: Tween 80 0.6 mL, dipotassium hydrogen phosphate 3.6 g and trisodium citrate 4.1 g (with culture volume of 1 L). In these conditions, the maximum EPS yield was 3.96±0.08 g/L. The optimal extraction conditions analyzed by CCD were: alcohol concentration 70 %, the ratio of material to liquid (M/L ratio) 1:3.6 and the extraction time 31 h. In these conditions, the maximum EPS extraction yield was 1.48±0.23 g/L. It was confirmed by the verification experiments that the EPS yield from L. acidophilus mutant strains reached 5.12±0.73 g/L under the optimized fermentation and extraction conditions, which was 3.8 times higher than that of the control (1.05±0.06 g/L). The results indicated that the strain screening with high-yielding EPS was successful and the optimized fermentation and extraction conditions significantly enhanced EPS yield. It was efficient and industrially promising. PMID:27103893

  18. Construction and Immunological Evaluation of Dual Cell Surface Display of HIV-1 Gag and Salmonella enterica Serovar Typhimurium FliC in Lactobacillus acidophilus for Vaccine Delivery

    PubMed Central

    Kajikawa, Akinobu; Zhang, Lin; Long, Julie; Nordone, Shila; Stoeker, Laura; LaVoy, Alora; Bumgardner, Sara; Klaenhammer, Todd

    2012-01-01

    Oral vaccines that elicit a mucosal immune response may be effective against human immunodeficiency virus type 1 (HIV-1) because its transmission occurs mainly at the mucosa. The aim of this study was to construct recombinant Lactobacillus for oral delivery of oral vaccines against HIV-1 and to evaluate their immunogenicity. A recombinant Lactobacillus acidophilus strain expressing the HIV-1 Gag on the bacterial cell surface was established by fusion with the signal peptide and anchor motif of a mucus binding protein (Mub) from L. acidophilus with or without coexpression of Salmonella enterica serovar Typhimurium flagellin (FliC) fused to a different Mub signal peptide and anchor. Using HEK293 cells engineered to express Toll-like receptor 5 (TLR5), the biological activity of FliC on the bacterial cell surfaces was determined. The surface-exposed flagellin retained its TLR5-stimulating activity, suggesting that the recombinant strain with Gag and FliC dual display might provide a different immunopotency than the strain expressing only Gag. The immunological properties of the recombinant strains were assessed by coculture with human myeloid dendritic cells (DCs). The heterologous antigens on the cell surface affected maturation and cytokine responses of DCs. Acquired immune responses were also investigated by intragastric immunization of mice. The enzyme-linked immunosorbent spot assay showed induction of gamma interferon-producing cells at local mucosa after immunization of mice with the Gag-producing strain. Meanwhile, the immunization with L. acidophilus displaying both Gag and FliC resulted in an increase of Gag-specific IgA-secreting cells. These results suggested that the Gag-displaying L. acidophilus elicited specific immune responses and the coexistence of FliC conferred an adjuvant effect on local IgA production. PMID:22761297

  19. Enteric coating of granules containing the probiotic Lactobacillus acidophilus.

    PubMed

    Pyar, Hassan; Peh, Kok-Khiang

    2014-06-01

    In the present study, a capsule formulation composed of enteric coated granules of Lactobacillus acidophilus ATCC 4962 was developed using Eudragit L30D-55 as enteric polymer. Optimization of the capsule formulation was achieved with a maximum viable cell count after 2 h of incubation in acid medium and disintegration time of 1 h in buffer pH 6.8. The amount of Eudragit L30D-55 in the capsules correlated with gastric juice resistance. The best protective qualities against artificial gastric juice were observed when capsules were prepared from granules composed of L. acidophilus, corn starch, lactose monohydrate, polyvinylpyrrolidone and coated with 12.5 % (m/V) of Eudragit L30D-55. Capsule formulation of L. acidophilus in edible broth medium suspension serves as a cheap alternative to the expensive freeze-drying procedure for preparing L. acidophilus. In addition, the enteric coating using Eudragit L30D-55 could protect probiotics from the acidic gastric environment and enhance the bioactivity of probiotics along with replacement of pathogenic microbes in human intestine. PMID:24914724

  20. Some probiotic and antibacterial properties of Lactobacillus acidophilus cultured from dahi a native milk product.

    PubMed

    Mahmood, Talat; Masud, Tariq; Sohail, Asma

    2014-08-01

    In this study, different strains of Lactobacillus acidophilus from dahi were analyzed for certain probiotic and antibacterial properties. Initially, these strains were confirmed by the amplification of 16S rRNA regions and then screened for antibacterial activities against food borne pathogens. The phenotypic relationship between apparent antibacterial activity and cell wall proteins were established by cluster analysis. It was observed that those strains, which have prominent bands having size 22-25 kDa possess antibacterial activity. On the basis of wide spectrum of killing pattern, a strain LA06FT was further characterized that showed no change in its behavior when subjected to the antibiotic protected environment and grow well in acid-bile conditions. The bacteriocin produced by this strain has specific antibacterial activity of 5369.13 AU mg(-1). It remained stable at 60-90 °C and pH range of 4.5-6.5 while proteolytic enzymes inactivate the bacteriocin that confirm its proteinic nature having molecular weight of ≤8.5 kDa. PMID:24689927

  1. Characterization of the temperate bacteriophage phi adh and plasmid transduction in Lactobacillus acidophilus ADH.

    PubMed Central

    Raya, R R; Kleeman, E G; Luchansky, J B; Klaenhammer, T R

    1989-01-01

    Lactobacillus acidophilus ADH is lysogenic and harbors an inducible prophage, phi adh. Bacteriophage were detected in cell lysates induced by treatment with mitomycin C or UV light. Electron microscopy of lysates revealed phage particles with a hexagonal head (62 nm) and a long, noncontractile, flexible tail (398 nm) ending in at last five short fibers. Phage phi adh was classified within Bradley's B1 phage group and the Siphoviridae family. The phi adh genome is a linear double-stranded DNA molecule of 41.7 kilobase pairs with cohesive ends: a physical map of the phi adh genome was constructed. A prophage-cured derivative of strain ADH, designated NCK102, was isolated from cells that survived UV exposure. NCK102 did not exhibit mitomycin C-induced lysis, but broth cultures lysed upon addition of phage. Phage phi adh produced clear plaques on NCK102 in media containing 10 mM CaCl2 at pH values between 5.2 and 5.5. A relysogenized derivative (NCK103) of NCK102 was isolated that exhibited mitomycin C-induced lysis and superinfection immunity to phage phi adh. Hybridization experiments showed that the phi adh genome was present in the ADH and NCK103 chromosomes, but absent in NCK102. These results demonstrated classic lytic and lysogenic cycles of replication for the temperate phage phi adh induced from L. acidophilus ADH. Phage phi adh also mediates transduction of plasmid DNA. Transductants of strain ADH containing pC194, pGK12, pGB354, and pVA797 were detected at frequencies in the range of 3.6 x 10(-8) to 8.3 x 10(-10) per PFU. Rearrangements or deletions were not detected in these plasmids as a consequence of transduction. This is the first description of plasmid transduction in the genus Lactobacillus. Images PMID:2508554

  2. Temporal gene expression and probiotic attributes of Lactobacillus acidophilus during growth in milk.

    PubMed

    Azcarate-Peril, M A; Tallon, R; Klaenhammer, T R

    2009-03-01

    Lactic acid bacteria have been used as starter strains in the production of fermented dairy products for centuries. Lactobacillus acidophilus is a widely recognized probiotic bacteria commonly added to yogurt and used in dietary supplements. In this study, a whole genome microarray was employed to monitor gene expression of L. acidophilus NCFM cells propagated in 11% skim milk during early, mid and late logarithmic phase, and stationary phase. Approximately 21% of 1,864 open reading frames were differentially expressed at least in one time point. Genes differentially expressed in skim milk included several members of the proteolytic enzyme system. Expression of prtP (proteinase precursor) and prtM (maturase) increased over time as well as several peptidases and transport systems. Expression of Opp1 (oligopeptide transport system 1) was highest at 4 h, whereas gene expression of Opp2 increased over time reaching its highest level at 12 h, suggesting that the 2 systems have different specificities. Expression of a 2-component regulatory system, previously shown to regulate acid tolerance and proteolytic activity, also increased during the early log and early stationary phases of growth. Expression of the genes involved in lactose utilization increased immediately (5 min) upon exposure to milk. The acidification activity, survival under storage conditions, and adhesion to mucin and Caco-2 tissue culture cells of selected mutants containing insertionally inactivated genes differentially expressed in the wild-type strain during growth in milk were examined for any potential links between probiotic properties and bacterial growth and survival in milk. Some of the most interesting genes found to be expressed in milk were correlated with signaling (autoinducer-2) and adherence to mucin and intestinal epithelial cells, in vitro. PMID:19233780

  3. [Study on effect of Lactobacillus acidophilus MG2-1 on serum lipid metabolism in rats].

    PubMed

    Menghe, Bilige; Zhang, He-Ping; Chen, Yong-Fu; Guan, Hong; Zhou, Dong-Po

    2005-12-01

    Wistar rats were fed with a high lipid diet supplemented with living or thermal death bacteria of Lactobacillus acidophilus MG2-1 which was isolated from koumiss in Mongolia and was of good ability of acid tolerance and decreasing the level of cholesterol in vitro. The effect of Lb. acidophilus MG2-1 on the metabolism of serum cholesterol was discussed. It was showed that it was on the 14th day of experiment that the inhibiting effects of the increase of serum cholesterol level of rat groups fed with living bacteria and heat-killed bacteria was significantly (p > 0.05) and very significantly (p < 0.01) higher than that of the high lipid diet group respectively; at the same time, the level of serum HDL-C of the thermal death bacteria group was significantly higher than that of the high lipid diet group (p < 0.05), also arteriosclerosis index of wistar rats in experimental group is significantly lower than that of the high lipid diet group (p < 0.01). The total bile acid level of the thermal death bacteria group in fecal is significantly higher than that of the high lipid diet group (p < 0.05). It is suggested that the increase of serum cholesterol level in rats can be inhibited and arteriosclerosis can also be prevented by this strain. During the period of tests, the effect of the strain on serum lipid in rats weaken with the time going, while the dose of bacteria fed was not changed. PMID:16496693

  4. Protein-mediated adhesion of Lactobacillus acidophilus BG2FO4 on human enterocyte and mucus-secreting cell lines in culture.

    PubMed Central

    Coconnier, M H; Klaenhammer, T R; Kernéis, S; Bernet, M F; Servin, A L

    1992-01-01

    The adhesion of Lactobacillus acidophilus BG2FO4, a human stool isolate, to two human enterocytelike cell lines (Caco-2 and HT-29) and to the mucus secreted by a subpopulation of mucus-secreting HT29-MTX cells was investigated. Scanning electron microscopy revealed that the bacteria interacted with the well-defined apical microvilli of Caco-2 cells without cell damage and with the mucus secreted by the subpopulation of HT29-MTX cells. The adhesion to Caco-2 cells did not require calcium and involved an adhesion-promoting factor that was present in the spent supernatant of L. acidophilus cultures. This factor promoted adhesion of poorly adhering human Lactobacillus casei GG but did not promote adhesion of L. casei CNRZ 387, a strain of dairy origin. The adherence components on the bacterial cells and in the spent supernatant were partially characterized. Carbohydrates on the bacterial cell wall appeared to be partly responsible for the interaction between the bacteria and the extracellular adhesion-promoting factor. The adhesion-promoting factor was proteinaceous, since trypsin treatment dramatically decreased the adhesion of the L. acidophilus strain. The adhesion-promoting factor may be an important component of Lactobacillus species that colonize the gastrointestinal tract. Images PMID:1622282

  5. Analysis of the human intestinal epithelial cell transcriptional response to Lactobacillus acidophilus, Lactobacillus salivarius, Bifidobacterium lactis and Escherichia coli.

    PubMed

    Putaala, H; Barrangou, R; Leyer, G J; Ouwehand, A C; Hansen, E Bech; Romero, D A; Rautonen, N

    2010-09-01

    The complex microbial population residing in the human gastrointestinal tract consists of commensal, potential pathogenic and beneficial species, which are probably perceived differently by the host and consequently could be expected to trigger specific transcriptional responses. Here, we provide a comparative analysis of the global in vitro transcriptional response of human intestinal epithelial cells to Lactobacillus acidophilus NCFM™, Lactobacillus salivarius Ls-33, Bifidobacterium animalis subsp. lactis 420, and enterohaemorrhagic Escherichia coli O157:H7 (EHEC). Interestingly, L. salivarius Ls-33 DCE-induced changes were overall more similar to those of B. lactis 420 than to L. acidophilus NCFM™, which is consistent with previously observed in vivo immunomodulation properties. In the gene ontology and pathway analyses both specific and unspecific changes were observed. Common to all was the regulation of apoptosis and adipogenesis, and lipid-metabolism related regulation by the probiotics. Specific changes such as regulation of cell-cell adhesion by B. lactis 420, superoxide metabolism by L. salivarius Ls-33, and regulation of MAPK pathway by L. acidophilus NCFM™ were noted. Furthermore, fundamental differences were observed between the pathogenic and probiotic treatments in the Toll-like receptor pathway, especially for adapter molecules with a lowered level of transcriptional activation of MyD88, TRIF, IRAK1 and TRAF6 by probiotics compared to EHEC. The results in this study provide insights into the relationship between probiotics and human intestinal epithelial cells, notably with regard to strain-specific responses, and highlight the differences between transcriptional responses to pathogenic and probiotic bacteria. PMID:21831765

  6. Complete Genome Sequence of Lactobacillus acidophilus MN-BM-F01

    PubMed Central

    Yang, Lan; Li, Zhiwei; Shi, Yudong; Li, Zhouyong; Zhao, Xiaohui

    2016-01-01

    Lactobacillus acidophilus MN-BM-F01 was originally isolated from a traditional fermented dairy product in China. The characteristics of this bacterium are its low post-acidification ability and high acid-producing rate. Here, we report the main genome features of L. acidophilus MN-BM-F01. PMID:26868391

  7. Synbiotic effects of lactitol and Lactobacillus acidophilus NCFM™ in a semi-continuous colon fermentation model.

    PubMed

    Mäkivuokko, H; Forssten, S; Saarinen, M; Ouwehand, A; Rautonen, N

    2010-06-01

    The effects of Lactobacillus acidophilus NCFM™, lactitol, and the combination of lactitol and L. acidophilus NCFM™ were studied with a semi-continuous colon fermentation simulation; consisting of compartments mimicking, ascending, transverse, descending and sigmoid colon and their conditions with faecal inoculation. L. acidophilus NCFM™ was detected throughout the colon simulator. Lactitol was utilised early on by the microbes in the proximal part of the simulator. Lactitol increased the total numbers of microbes and bifidobacteria, and decreased clostridia cluster IV, while L. acidophilus NCFM™ alone decreased the numbers of clostridia cluster XIV. Combination treatment increased the numbers of bifidobacteria. Furthermore, concentrations of acetic acid, butyric acid and the sum of total short-chain fatty acids were increased by both lactitol-including treatments. The treatment with L. acidophilus NCFM™ alone increased the concentration of propionic acid and butyric acid. L. acidophilus NCFM™ tended to increase the total concentrations of biogenic amines, while lactitol suppressed production of biogenic amines also in the presence of L. acidophilus NCFM™. True synergistic effects are suggested in stimulation of the production of butyrate, an important microbial metabolite for colon health. In conclusion, lactitol as well as the combination of lactitol and L. acidophilus NCFM™ were found to exhibit complementary beneficial effects on the colon microbial composition and activity. PMID:21840801

  8. AcmB Is an S-Layer-Associated β-N-Acetylglucosaminidase and Functional Autolysin in Lactobacillus acidophilus NCFM

    PubMed Central

    Johnson, Brant R.

    2016-01-01

    ABSTRACT Autolysins, also known as peptidoglycan hydrolases, are enzymes that hydrolyze specific bonds within bacterial cell wall peptidoglycan during cell division and daughter cell separation. Within the genome of Lactobacillus acidophilus NCFM, there are 11 genes encoding proteins with peptidoglycan hydrolase catalytic domains, 9 of which are predicted to be functional. Notably, 5 of the 9 putative autolysins in L. acidophilus NCFM are S-layer-associated proteins (SLAPs) noncovalently colocalized along with the surface (S)-layer at the cell surface. One of these SLAPs, AcmB, a β-N-acetylglucosaminidase encoded by the gene lba0176 (acmB), was selected for functional analysis. In silico analysis revealed that acmB orthologs are found exclusively in S-layer- forming species of Lactobacillus. Chromosomal deletion of acmB resulted in aberrant cell division, autolysis, and autoaggregation. Complementation of acmB in the ΔacmB mutant restored the wild-type phenotype, confirming the role of this SLAP in cell division. The absence of AcmB within the exoproteome had a pleiotropic effect on the extracellular proteins covalently and noncovalently bound to the peptidoglycan, which likely led to the observed decrease in the binding capacity of the ΔacmB strain for mucin and extracellular matrices fibronectin, laminin, and collagen in vitro. These data suggest a functional association between the S-layer and the multiple autolysins noncovalently colocalized at the cell surface of L. acidophilus NCFM and other S-layer-producing Lactobacillus species. IMPORTANCE Lactobacillus acidophilus is one of the most widely used probiotic microbes incorporated in many dairy foods and dietary supplements. This organism produces a surface (S)-layer, which is a self-assembling crystalline array found as the outermost layer of the cell wall. The S-layer, along with colocalized associated proteins, is an important mediator of probiotic activity through intestinal adhesion and modulation of

  9. Predominant genera of fecal microbiota in children with atopic dermatitis are not altered by intake of probiotic bacteria Lactobacillus acidophilus NCFM and Bifidobacterium animalis subsp. lactis Bi-07.

    PubMed

    Larsen, Nadja; Vogensen, Finn K; Gøbel, Rikke; Michaelsen, Kim F; Abu Al-Soud, Waleed; Sørensen, Søren J; Hansen, Lars H; Jakobsen, Mogens

    2011-03-01

    The effect of probiotic bacteria Lactobacillus acidophilus NCFM and Bifidobacterium lactis Bi-07 on the composition of the Lactobacillus group, Bifidobacterium and the total bacterial population in feces from young children with atopic dermatitis was investigated. The study included 50 children randomized to intake of one of the probiotic strain or placebo. Microbial composition was characterized by denaturing gradient gel electrophoresis, quantitative PCR and, in a subset of subjects, by pyrosequencing of the 16S rRNA gene. The core population of the Lactobacillus group was identified as Lactobacillus gasseri, Lactobacillus fermentum, Lactobacillus oris, Leuconostoc mesenteroides, while the bifidobacterial community included Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium longum and Bifidobacterium catenulatum. The fecal numbers of L. acidophilus and B. lactis increased significantly after intervention, indicating survival of the ingested bacteria. The levels of Bifidobacterium correlated positively (P=0.03), while the levels of the Lactobacillus group negatively (P=0.01) with improvement of atopic eczema evaluated by the Severity Scoring of Atopic Dermatitis index. This correlation was observed across the whole study cohort and not attributed to the probiotic intake. The main conclusion of the study is that administration of L. acidophilus NCFM and B. lactis Bi-07 does not affect the composition and diversity of the main bacterial populations in feces. PMID:21204871

  10. Functional and phenotypic characterization of a protein from Lactobacillus acidophilus involved in cell morphology, stress tolerance and adherence to intestinal cells.

    PubMed

    O'Flaherty, Sarah J; Klaenhammer, Todd R

    2010-11-01

    Structural components of the cell surface have an impact on some of the beneficial attributes of probiotic bacteria. In silico analysis of the L. acidophilus NCFM genome sequence revealed the presence of a putative cell surface protein that was predicted to be a myosin cross-reactive antigen (MCRA). As MCRAs are conserved among many probiotic bacteria, we used the upp-based counterselective gene replacement system, designed recently for use in L. acidophilus, to determine the functional role of this gene (LBA649) in L. acidophilus NCFM. Phenotypic assays were undertaken with the parent strain (NCK1909) and deletion mutant (NCK2015) to assign a function for this gene. The growth of NCK2015 (ΔLBA649) was reduced in the presence of lactate, acetate, porcine bile and salt. Adhesion of NCK2015 to Caco-2 cells was substantially reduced for both stationary-phase (∼45 % reduction) and exponential-phase cells (∼50 % reduction). Analysis of NCK2015 by scanning electron microscopy revealed a longer cell morphology after growth in MRS broth compared to NCK1909. These results indicate a role for LBA649 in stress tolerance, cell wall division and adherence to Caco-2 cells. PMID:20829293

  11. Ingestion of yogurt containing Lactobacillus acidophilus and Bifidobacterium to potentiate immunoglobulin A responses to cholera toxin in mice.

    PubMed

    Tejada-Simon, M V; Lee, J H; Ustunol, Z; Pestka, J J

    1999-04-01

    Lactic acid bacteria have been reported to have benefits for the prevention and treatment of some forms of diarrhea and related conditions. To determine whether these effects might involve direct stimulation of the gastrointestinal immune response, we administered yogurt to try to enhance mucosal and systemic antibodies against an orally presented immunogen, cholera toxin. Yogurts were manufactured with starter cultures containing different species and strains of lactic acid bacteria. Mice were fed these yogurts for 3 wk, during which they were also orally immunized twice with 10 micrograms of cholera toxin. Blood was collected on d 0 and 21, and fecal pellets were collected weekly. Mice that were immunized orally with cholera toxin responded by producing specific intestinal and serum immunoglobulin (Ig)A anti-cholera toxin. Antibody responses of the IgA isotype were significantly increased in mice fed yogurts made with starters containing the conventional yogurt bacteria Lactobacillus bulgaricus and Streptococcus thermophilus supplemented with Lactobacillus acidophilus, Bifidobacterium bifidum, and Bifidobacterium infantis. Yogurt that was manufactured with starters containing only conventional yogurt bacteria produced less IgA anti-cholera toxin than did the control group fed nonfat dry milk. Although strong responses were also observed for IgG anti-cholera toxin in serum, the responses did not differ among groups. Thus, administration of yogurt supplemented with L. acidophilus and Bifidobacterium spp. enhanced mucosal and systemic IgA responses to the cholera toxin immunogen. PMID:10212452

  12. Mucosal Immunogenicity of Genetically Modified Lactobacillus acidophilus Expressing an HIV-1 Epitope within the Surface Layer Protein.

    PubMed

    Kajikawa, Akinobu; Zhang, Lin; LaVoy, Alora; Bumgardner, Sara; Klaenhammer, Todd R; Dean, Gregg A

    2015-01-01

    Surface layer proteins of probiotic lactobacilli are theoretically efficient epitope-displaying scaffolds for oral vaccine delivery due to their high expression levels and surface localization. In this study, we constructed genetically modified Lactobacillus acidophilus strains expressing the membrane proximal external region (MPER) from human immunodeficiency virus type 1 (HIV-1) within the context of the major S-layer protein, SlpA. Intragastric immunization of mice with the recombinants induced MPER-specific and S-layer protein-specific antibodies in serum and mucosal secretions. Moreover, analysis of systemic SlpA-specific cytokines revealed that the responses appeared to be Th1 and Th17 dominant. These findings demonstrated the potential use of the Lactobacillus S-layer protein for development of oral vaccines targeting specific peptides. PMID:26509697

  13. Mucosal Immunogenicity of Genetically Modified Lactobacillus acidophilus Expressing an HIV-1 Epitope within the Surface Layer Protein

    PubMed Central

    Kajikawa, Akinobu; Zhang, Lin; LaVoy, Alora; Bumgardner, Sara; Klaenhammer, Todd R.; Dean, Gregg A.

    2015-01-01

    Surface layer proteins of probiotic lactobacilli are theoretically efficient epitope-displaying scaffolds for oral vaccine delivery due to their high expression levels and surface localization. In this study, we constructed genetically modified Lactobacillus acidophilus strains expressing the membrane proximal external region (MPER) from human immunodeficiency virus type 1 (HIV-1) within the context of the major S-layer protein, SlpA. Intragastric immunization of mice with the recombinants induced MPER-specific and S-layer protein-specific antibodies in serum and mucosal secretions. Moreover, analysis of systemic SlpA-specific cytokines revealed that the responses appeared to be Th1 and Th17 dominant. These findings demonstrated the potential use of the Lactobacillus S-layer protein for development of oral vaccines targeting specific peptides. PMID:26509697

  14. In vivo gut transcriptome responses to Lactobacillus rhamnosus GG and Lactobacillus acidophilus in neonatal gnotobiotic piglets

    PubMed Central

    Kumar, Anand; Vlasova, Anastasia N; Liu, Zhe; Chattha, Kuldeep S; Kandasamy, Sukumar; Esseili, Malak; Zhang, Xiaoli; Rajashekara, Gireesh; Saif, Linda J

    2014-01-01

    Probiotics facilitate mucosal repair and maintain gut homeostasis. They are often used in adjunct with rehydration or antibiotic therapy in enteric infections. Lactobacillus spp have been tested in infants for the prevention or treatment of various enteric conditions. However, to aid in rational strain selection for specific treatments, comprehensive studies are required to delineate and compare the specific molecules and pathways involved in a less complex but biologically relevant model (gnotobiotic pigs). Here we elucidated Lactobacillus rhamnosus (LGG) and L. acidophilus (LA) specific effects on gut transcriptome responses in a neonatal gnotobiotic (Gn) pig model to simulate responses in newly colonized infants. Whole genome microarray, followed by biological pathway reconstruction, was used to investigate the host-microbe interactions in duodenum and ileum at early (day 1) and later stages (day 7) of colonization. Both LA and LGG modulated common responses related to host metabolism, gut integrity, and immunity, as well as responses unique to each strain in Gn pigs. Our data indicated that probiotic establishment and beneficial effects in the host are guided by: (1) down-regulation or upregulation of immune function-related genes in the early and later stages of colonization, respectively, and (2) alternations in metabolism of small molecules (vitamins and/or minerals) and macromolecules (carbohydrates, proteins, and lipids). Pathways related to immune modulation and carbohydrate metabolism were more affected by LGG, whereas energy and lipid metabolism-related transcriptome responses were prominently modulated by LA. These findings imply that identification of probiotic strain-specific gut responses could facilitate the rational design of probiotic-based interventions to moderate specific enteric conditions. PMID:24637605

  15. Lactobacillus acidophilus NCFM affects vitamin E acetate metabolism and intestinal bile acid signature in monocolonized mice

    PubMed Central

    Roager, Henrik M; Sulek, Karolina; Skov, Kasper; Frandsen, Henrik L; Smedsgaard, Jørn; Wilcks, Andrea; Skov, Thomas H; Villas-Boas, Silas G; Licht, Tine R

    2014-01-01

    Monocolonization of germ-free (GF) mice enables the study of specific bacterial species in vivo. Lactobacillus acidophilus NCFMTM (NCFM) is a probiotic strain; however, many of the mechanisms behind its health-promoting effect remain unknown. Here, we studied the effects of NCFM on the metabolome of jejunum, cecum, and colon of NCFM monocolonized (MC) and GF mice using liquid chromatography coupled to mass-spectrometry (LC-MS). The study adds to existing evidence that NCFM in vivo affects the bile acid signature of mice, in particular by deconjugation. Furthermore, we confirmed that carbohydrate metabolism is affected by NCFM in the mouse intestine as especially the digestion of oligosaccharides (penta- and tetrasaccharides) was increased in MC mice. Additionally, levels of α-tocopherol acetate (vitamin E acetate) were higher in the intestine of GF mice than in MC mice, suggesting that NCFM affects the vitamin E acetate metabolism. NCFM did not digest vitamin E acetate in vitro, suggesting that direct bacterial metabolism was not the cause of the altered metabolome in vivo. Taken together, our results suggest that NCFM affects intestinal carbohydrate metabolism, bile acid metabolism and vitamin E metabolism, although it remains to be investigated whether this effect is unique to NCFM. PMID:24717228

  16. SIGNR3-dependent immune regulation by Lactobacillus acidophilus surface layer protein A in colitis

    PubMed Central

    Lightfoot, Yaíma L; Selle, Kurt; Yang, Tao; Goh, Yong Jun; Sahay, Bikash; Zadeh, Mojgan; Owen, Jennifer L; Colliou, Natacha; Li, Eric; Johannssen, Timo; Lepenies, Bernd; Klaenhammer, Todd R; Mohamadzadeh, Mansour

    2015-01-01

    Intestinal immune regulatory signals govern gut homeostasis. Breakdown of such regulatory mechanisms may result in inflammatory bowel disease (IBD). Lactobacillus acidophilus contains unique surface layer proteins (Slps), including SlpA, SlpB, SlpX, and lipoteichoic acid (LTA), which interact with pattern recognition receptors to mobilize immune responses. Here, to elucidate the role of SlpA in protective immune regulation, the NCK2187 strain, which solely expresses SlpA, was generated. NCK2187 and its purified SlpA bind to the C-type lectin SIGNR3 to exert regulatory signals that result in mitigation of colitis, maintenance of healthy gastrointestinal microbiota, and protected gut mucosal barrier function. However, such protection was not observed in Signr3−/− mice, suggesting that the SlpA/SIGNR3 interaction plays a key regulatory role in colitis. Our work presents critical insights into SlpA/SIGNR3-induced responses that are integral to the potential development of novel biological therapies for autoinflammatory diseases, including IBD. PMID:25666591

  17. Lactobacillus acidophilus NCFM affects vitamin E acetate metabolism and intestinal bile acid signature in monocolonized mice.

    PubMed

    Roager, Henrik M; Sulek, Karolina; Skov, Kasper; Frandsen, Henrik L; Smedsgaard, Jørn; Wilcks, Andrea; Skov, Thomas H; Villas-Boas, Silas G; Licht, Tine R

    2014-01-01

    Monocolonization of germ-free (GF) mice enables the study of specific bacterial species in vivo. Lactobacillus acidophilus NCFM(TM) (NCFM) is a probiotic strain; however, many of the mechanisms behind its health-promoting effect remain unknown. Here, we studied the effects of NCFM on the metabolome of jejunum, cecum, and colon of NCFM monocolonized (MC) and GF mice using liquid chromatography coupled to mass-spectrometry (LC-MS). The study adds to existing evidence that NCFM in vivo affects the bile acid signature of mice, in particular by deconjugation. Furthermore, we confirmed that carbohydrate metabolism is affected by NCFM in the mouse intestine as especially the digestion of oligosaccharides (penta- and tetrasaccharides) was increased in MC mice. Additionally, levels of α-tocopherol acetate (vitamin E acetate) were higher in the intestine of GF mice than in MC mice, suggesting that NCFM affects the vitamin E acetate metabolism. NCFM did not digest vitamin E acetate in vitro, suggesting that direct bacterial metabolism was not the cause of the altered metabolome in vivo. Taken together, our results suggest that NCFM affects intestinal carbohydrate metabolism, bile acid metabolism and vitamin E metabolism, although it remains to be investigated whether this effect is unique to NCFM. PMID:24717228

  18. Bacterial Endocarditis Caused by Lactobacillus acidophilus Leading to Rupture of Sinus of Valsalva Aneurysm

    PubMed Central

    Loranger, Austin Mitchell; Bharatkumar, A.G.; Almassi, G. Hossein

    2016-01-01

    Lactobacillus acidophilus rarely causes bacterial endocarditis, because it usually resides in the mucosa of the vagina, gastrointestinal tract, and oropharynx. Moreover, sinus of Valsalva aneurysms are rare cardiac anomalies, either acquired or congenital. We present the case of a middle-aged man whose bacterial endocarditis, caused by Lactobacillus acidophilus, led to an aneurysmal rupture of the sinus of Valsalva into the right ventricular outflow tract. The patient underwent successful surgical repair, despite numerous complications and sequelae. PMID:27127435

  19. Lactobacillus acidophilus LA 1 binds to cultured human intestinal cell lines and inhibits cell attachment and cell invasion by enterovirulent bacteria.

    PubMed Central

    Bernet, M F; Brassart, D; Neeser, J R; Servin, A L

    1994-01-01

    Four human Lactobacillus acidophilus strains were tested for their ability to adhere onto human enterocyte like Caco-2 cells in culture. The LA 1 strain exhibited a high calcium independent adhesive property. This adhesion onto Caco-2 cells required a proteinaceous adhesion promoting factor, which was present in the spent bacterial broth culture supernatant. LA 1 strain also strongly bound to the mucus secreted by the homogeneous cultured human goblet cell line HT29-MTX. The inhibitory effect of LA 1 organisms against Caco-2 cell adhesion and cell invasion by a large variety of diarrhoeagenic bacteria was investigated. As a result, the following dose dependent inhibitions were obtained: (a) against the cell association of enterotoxigenic, diffusely adhering and enteropathogenic Escherichia coli, and Salmonella typhimurium; (b) against the cell invasion by enteropathogenic Escherichia coli, Yersinia pseudotuberculosis, and Salmonella typhimurium. Incubations of L acidophilus LA 1 before and together with enterovirulent E coli were more effective than incubation after infection by E coli. Images Figure 1 Figure 2 PMID:8174985

  20. Lactobacillus acidophilus LA 1 binds to cultured human intestinal cell lines and inhibits cell attachment and cell invasion by enterovirulent bacteria.

    PubMed

    Bernet, M F; Brassart, D; Neeser, J R; Servin, A L

    1994-04-01

    Four human Lactobacillus acidophilus strains were tested for their ability to adhere onto human enterocyte like Caco-2 cells in culture. The LA 1 strain exhibited a high calcium independent adhesive property. This adhesion onto Caco-2 cells required a proteinaceous adhesion promoting factor, which was present in the spent bacterial broth culture supernatant. LA 1 strain also strongly bound to the mucus secreted by the homogeneous cultured human goblet cell line HT29-MTX. The inhibitory effect of LA 1 organisms against Caco-2 cell adhesion and cell invasion by a large variety of diarrhoeagenic bacteria was investigated. As a result, the following dose dependent inhibitions were obtained: (a) against the cell association of enterotoxigenic, diffusely adhering and enteropathogenic Escherichia coli, and Salmonella typhimurium; (b) against the cell invasion by enteropathogenic Escherichia coli, Yersinia pseudotuberculosis, and Salmonella typhimurium. Incubations of L acidophilus LA 1 before and together with enterovirulent E coli were more effective than incubation after infection by E coli. PMID:8174985

  1. Antagonistic activity of Lactobacillus acidophilus LA10 against Salmonella enterica serovar Enteritidis SE86 in mice

    PubMed Central

    Scapin, Diane; Grando, Williani Fabiola; Rossi, Eliandra Mirlei; Perez, Karla Joseane; Malheiros, Patrícia da Silva; Tondo, Eduardo Cesar

    2013-01-01

    Salmonella enterica serovar Enteritidis is one of the main pathogens responsible for foodborne illness in Brazil. Probiotic bacteria can play a role in defense and recovery from enteropathogenic infections. In this study, the ability of Lactobacillus acidophilus LA10 to colonise and exert antagonistic effects in the gastrointestinal tract was tested before and during experimental infection in conventional mice contaminated with S. Enteritidis (SE86). A dose of 0.1 mL containing 108 viable cells of SE86 and L. acidophilus LA10 was orally administered by gavage to mice. The experiment was divided into groups. As a negative control, Group 1 was administered only sterile saline solution. As a positive control, Group 2 was administered only SE86. Group 3 was first administered SE86, and after 10 days, treated with L. acidophilus LA10. Group 4 was first administered L. acidophilus LA10, and after 10 days, challenged with SE86. The results demonstrated that a significant number of SE86 cells were able to colonize the gastrointestinal tract of mice, specifically in the colon and ileum. L. acidophilus LA10 demonstrated an antagonistic effect against SE86, with better results observed for Group 3 over Group 4. Thus, L. acidophilus LA10 shows potential antagonistic effects against S. Enteritidis SE86, especially if administered after infection. PMID:24159284

  2. Effects of Lactobacillus acidophilus NCFM on insulin sensitivity and the systemic inflammatory response in human subjects.

    PubMed

    Andreasen, Anne Sofie; Larsen, Nadja; Pedersen-Skovsgaard, Theis; Berg, Ronan M G; Møller, Kirsten; Svendsen, Kira Dynnes; Jakobsen, Mogens; Pedersen, Bente Klarlund

    2010-12-01

    According to animal studies, intake of probiotic bacteria may improve glucose homeostasis. We hypothesised that probiotic bacteria improve insulin sensitivity by attenuating systemic inflammation. Therefore, the effects of oral supplementation with the probiotic bacterium Lactobacillus acidophilus NCFM on insulin sensitivity and the inflammatory response were investigated in subjects with normal or impaired insulin sensitivity. In a double-blinded, randomised fashion, forty-five males with type 2 diabetes, impaired or normal glucose tolerance were enrolled and allocated to a 4-week treatment course with either L. acidophilus NCFM or placebo. L. acidophilus was detected in stool samples by denaturating gradient gel electrophoresis and real-time PCR. Separated by the 4-week intervention period, two hyperinsulinaemic-euglycaemic clamps were performed to estimate insulin sensitivity. Furthermore, the systemic inflammatory response was evaluated by subjecting the participants to Escherichia coli lipopolysaccharide injection (0·3 ng/kg) before and after the treatment course. L. acidophilus NCFM was detected in 75 % of the faecal samples after treatment with the probiotic bacterium. Insulin sensitivity was preserved among volunteers in the L. acidophilus NCFM group, whereas it decreased in the placebo group. Both baseline inflammatory markers and the systemic inflammatory response were, however, unaffected by the intervention. In conclusion, intake of L. acidophilus NCFM for 4 weeks preserved insulin sensitivity compared with placebo, but did not affect the systemic inflammatory response. PMID:20815975

  3. Phenol degradation by Sulfobacillus acidophilus TPY via the meta-pathway.

    PubMed

    Zhou, Wengen; Guo, Wenbin; Zhou, Hongbo; Chen, Xinhua

    2016-09-01

    Due to its toxicity and volatility, phenol must be cleared from the environment. Sulfobacillus acidophilus TPY, which was isolated from a hydrothermal vent in the Pacific Ocean as a moderately thermoacidophilic Gram-positive bacterium, was capable of aerobically degrading phenol. This bacterium could tolerate up to 1300mg/L phenol and degrade 100mg/L phenol in 40h completely at 45°C and pH 1.8 with a maximal degradation rate of 2.32mg/L/h at 38h. Genome-wide search revealed that one gene (TPY_3176) and 14 genes clustered together in two regions with locus tags of TPY_0628-0634 and TPY_0640-0646 was proposed to be involved in phenol degradation via the meta-pathway with both the 4-oxalocrotonate branch and the hydrolytic branch. Real-time PCR analysis of S. acidophilus TPY under phenol cultivation condition confirmed the transcription of proposed genes involved in the phenol degradation meta-pathway. Degradation of 3-methylphenol and 2-methylphenol confirmed that the hydrolytic branch was utilised by S. acidophilus TPY. Phylogenetic analysis revealed that S. acidophilus TPY was closely related to sulphate-reducing bacteria and some Gram-positive phenol-degrading bacteria. This was the first report demonstrating the ability of S. acidophilus to degrade phenol and characterising the putative genes involved in phenol metabolism in S. acidophilus TPY. PMID:27393997

  4. Growth and metabolism of selected strains of probiotic bacteria, in maize porridge with added malted barley.

    PubMed

    Helland, Merete H; Wicklund, Trude; Narvhus, Judith A

    2004-03-15

    A fermented probiotic maize porridge with high energy density and low viscosity was prepared, using maize flour and barley malt. The porridge was fermented with four probiotic strains (grown separately): Lactobacillus reuteri, Lb. acidophilus (LA5 and 1748) and Lb. rhamnosus GG. These strains were inoculated at two levels; to obtain approx. 7 or 6 log cfu g(-1) in the porridge at 0 h. The porridge was fermented for 24 h at 37 degrees C, and analysed for viable cell count, pH, organic acids, volatile aromatic compounds and sugar content. The inoculated cell concentration was shown to be particularly important during the first hours of the fermentation period, showing a delayed production of most metabolites in porridge inoculated with approx. 6 log cfu g(-1). Most strains reached maximum cell count after 12-h fermentation (7.2-8.2 log cfu g(-1)), with a pH below 4.0. Depending on the strain, lactic acid was produced in amounts ranging from 1360 to 4000 mg kg(-1). Lb. reuteri metabolised succinate, while pyruvate and small amounts of diacetyl were detected in porridge inoculated with Lb. acidophilus LA5 and Lb. acidophilus 1748. High amounts of diacetyl (6 mg kg(-1)) and acetoin (27 mg kg(-1)) were detected in porridge inoculated with Lb. rhamnosus GG. Porridge inoculated with Lb. acidophilus LA5 and Lb. acidophilus 1748, contained acetaldehyde, while both Lb. reuteri and Lb. rhamnosus GG reduced the acetaldehyde to ethanol. Lb. reuteri utilised both maltose and glucose as carbohydrate sources, while Lb. acidophilus LA5, Lb. acidophilus 1748 and Lb. rhamnosus GG utilised only glucose. PMID:14984778

  5. Identification of Lactobacillus UFV H2B20 (probiotic strain) using DNA-DNA hybridization

    PubMed Central

    de Magalhães, J.T.; Uetanabaro, A.P. T.; de Moraes, C.A.

    2008-01-01

    Sequence analyses of the 16S rDNA gene and DNA-DNA hybridization tests were performed for identification of the species of the probiotic Lactobacillus UFV H2b20 strain. Using these two tests, we concluded that this strain, originally considered Lact. acidophilus, should be classified as Lact. delbrueckii. PMID:24031263

  6. Functional roles of aggregation-promoting-like factor in stress tolerance and adherence of Lactobacillus acidophilus NCFM.

    PubMed

    Goh, Yong Jun; Klaenhammer, Todd R

    2010-08-01

    Aggregation-promoting factors (Apf) are secreted proteins that have been associated with a diverse number of functional roles in lactobacilli, including self-aggregation, the bridging of conjugal pairs, coaggregation with other commensal or pathogenic bacteria, and maintenance of cell shape. In silico genome analysis of Lactobacillus acidophilus NCFM identified LBA0493 as a 696-bp apf gene that encodes a putative 21-kDa Apf protein. Transcriptional studies of NCFM during growth in milk showed apf to be one of the most highly upregulated genes in the genome. In the present study, reverse transcriptase-quantitative PCR (RT-QPCR) analysis revealed that the apf gene was highly induced during the stationary phase compared to that during the logarithmic phase. To investigate the functional role of Apf in NCFM, an Delta apf deletion mutant was constructed. The resulting Delta apf mutant, NCK2033, did not show a significant difference in cell morphology or growth compared to that of the NCFMDelta upp reference strain, NCK1909. The autoaggregation phenotype of NCK2033 in planktonic culture was unaffected. Additional phenotypic assays revealed that NCK2033 was more susceptible to treatments with oxgall bile and sodium dodecyl sulfate (SDS). Survival rates of NCK2033 decreased when stationary-phase cells were exposed to simulated small-intestinal and gastric juices. Furthermore, NCK2033 in the stationary phase showed a reduction of in vitro adherence to Caco-2 intestinal epithelial cells, mucin glycoproteins, and fibronectin. The data suggest that the Apf-like proteins may contribute to the survival of L. acidophilus during transit through the digestive tract and, potentially, participate in the interactions with the host intestinal mucosa. PMID:20562289

  7. Probiotic cheese containing Lactobacillus rhamnosus HN001 and Lactobacillus acidophilus NCFM® modifies subpopulations of fecal lactobacilli and Clostridium difficile in the elderly.

    PubMed

    Lahtinen, Sampo J; Forssten, Sofia; Aakko, Juhani; Granlund, Linda; Rautonen, Nina; Salminen, Seppo; Viitanen, Matti; Ouwehand, Arthur C

    2012-02-01

    Aging is associated with alterations in the intestinal microbiota and with immunosenescence. Probiotics have the potential to modify a selected part of the intestinal microbiota as well as improve immune functions and may, therefore, be particularly beneficial to elderly consumers. In this randomized, controlled cross-over clinical trial, we assessed the effects of a probiotic cheese containing Lactobacillus rhamnosus HN001 and Lactobacillus acidophilus NCFM on the intestinal microbiota and fecal immune markers of 31 elderly volunteers and compared these effects with the administration of the same cheese without probiotics. The probiotic cheese was found to increase the number of L. rhamnosus and L. acidophilus NCFM in the feces, suggesting the survival of the strains during the gastrointestinal transit. Importantly, probiotic cheese administration was associated with a trend towards lower counts of Clostridium difficile in the elderly, as compared with the run-in period with the plain cheese. The effect was statistically significant in the subpopulation of the elderly who harbored C. difficile at the start of the study. The probiotic cheese was not found to significantly alter the levels of the major microbial groups, suggesting that the microbial changes conferred by the probiotic cheese were limited to specific bacterial groups. Despite that the administration of the probiotic cheese to the study population has earlier been shown to significantly improve the innate immunity of the elders, we did not observe measurable changes in the fecal immune IgA concentrations. No increase in fecal calprotectin and β-defensin concentrations suggests that the probiotic treatment did not affect intestinal inflammatory markers. In conclusion, the administration of probiotic cheese containing L. rhamnosus HN001 and L. acidophilus NCFM, was associated with specific changes in the intestinal microbiota, mainly affecting specific subpopulations of intestinal lactobacilli and C

  8. A prebiotic mixture improved Lactobacillus acidophilus and Bifidobacterium animalis gastrointestinal in vitro resistance in petit-suisse.

    PubMed

    Padilha, Marina; Villarreal Morales, Martha Lissete; Vieira, Antonio Diogo Silva; Costa, Mayra Garcia Maia; Saad, Susana Marta Isay

    2016-05-18

    The survival of two probiotic strains -Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 - incorporated into probiotic (PC) and into synbiotic (SC, with inulin + fructooligosaccharides, respectively, at 7.5 and at 2.5 g per 100 g) petit-suisse cheese was investigated in the beginning (day 1) and at the end (28 days) of storage at 4 °C when the food products were subjected to in vitro gastrointestinal simulated assays. Species-specific quantitative real time PCR (qPCR) combined with propidium monoazide (PMA-qPCR) was employed to quantify the strains. Initial La-5 and Bb-12 populations were always above 7 log CFU g(-1). The presence of the prebiotic ingredients in SC improved the Bb-12 and La-5 resistance after the 6 h assay, with higher populations in all the in vitro stages and throughout the storage period (p < 0.05), leading to equal or superior survival rates (SR) in SC of both probiotic strains, in the beginning as well as at the end of storage. The mean La-5 SR were 58% (PC) and 67% (SC), whereas the mean Bb-12 SR were 60% (PC) and 79% (SC). Our findings suggest that the addition of a prebiotic mixture in petit-suisse cheese was advantageous, since it improved both the Bb-12 and La-5 viability and tolerance under in vitro gastrointestinal simulated conditions, both in the fresh product and in the product refrigerated for 28 days. PMID:27112363

  9. Lactobacillus acidophilus maintained oxidative stress from reproductive organs in collagen-induced arthritic rats

    PubMed Central

    Amdekar, Sarika; Singh, Vinod

    2016-01-01

    CONTEXTS: Nonsteroidal anti-inflammatory drugs (NSAIDs) induced organ damage is a well-known fact. Previous studies suggest that Lactobacillus scavenge the free radicals from liver and kidney and also protect animals from arthritis. AIMS: Comparing protective properties of Lactobacillus acidophilus in reducing oxidative stress from reproductive organs developed during collagen-induced arthritis in animal model. METHODS: Arthritis was induced in Wistar rats. Oral administration of L. acidophilus, indomethacin, and distilled water were all started on the same day. Arthritis scores were calculated for each group. Oxidative stress parameters were estimated in testis and ovary homogenates. Histopathology of ovary and testis was also performed. RESULTS AND CONCLUSION: L. acidophilus decreased arthritis score (P < 0.001) as well as maintained normal histology of reproductive organs. L. acidophilus maintained oxidative stress parameters from ovaries and testis (P < 0.001). These results provide strong evidence that NSAIDs increase oxidative stress in reproductive organs while L. acidophilus not only scavenges free radicals from reproductive organs but also protects rats from arthritis symptoms. PMID:27110077

  10. Effect of Lactobacillus acidophilus KFRI342 on the development of chemically induced precancerous growths in the rat colon.

    PubMed

    Chang, Jin-Hee; Shim, Youn Young; Cha, Seong-Kwan; Reaney, Martin J T; Chee, Kew Mahn

    2012-03-01

    Lactobacillus acidophilus KFRI342, isolated from the Korean traditional food kimchi, was investigated for its suitability as a dietary probiotic. The effects of L. acidophilus KFRI342 on the development of chemically induced (1,2-dimethylhydrazine; DMH) precancerous cytological changes of the colon were investigated in rats. Forty-five male F344 rats were randomly divided into three dietary groups. The control group received a high-fat diet (HF), a second group received a high-fat diet containing the carcinogen (HFC), and a final group received a high-fat diet containing the carcinogen and L. acidophilus KFRI342 (HFCL). L. acidophilus KFRI342 was administered orally three times per week at 2×10(9) c.f.u. ml(-1). L. acidophilus KFRI342 treatments decreased the number of Escherichia coli in faecal samples, the enzyme activities of β-glucuronidase and β-glucosidase, and plasma triglyceride concentration compared to the HF and HFC treatments (P<0.05). L. acidophilus KFRI342 consumption also decreased the ratio of aberrant crypts to aberrant crypt foci incidence and the number of aberrant crypts in HFCL rats. Therefore, L. acidophilus showed potential probiotic activity as an inhibitor of DMH-induced symptoms in live rats. Our in vivo studies indicate that L. acidophilus from kimchi may be suitable as a probiotic for human use. PMID:22034161

  11. Osmotically regulated transport of proline by Lactobacillus acidophilus IFO 3532.

    PubMed

    Jewell, J B; Kashket, E R

    1991-10-01

    We reported previously that, when exposed to high osmotic pressure, Lactobacillus acidophilus IFO 3532 cells accumulated N,N,N-trimethylglycine (glycine betaine), which serves as a compatible intracellular solute. When grown in medium with high osmotic pressure, these cells also accumulated one amino acid, proline. The uptake of [3H]proline by resting, glucose-energized cells was stimulated by increasing the osmotic pressure of the assay medium with 0.5 to 1.0 M KCl, 1.0 M NaCl, or 0.5 M sucrose. The accumulated [3H]proline was not metabolized further. In contrast, there was no osmotic stimulation of [3H]leucine uptake. The uptake of proline was activated rather than induced by exposure of the cells to high osmotic pressure. Only one proline transport system could be discerned from kinetics plots. The affinity of the carrier for proline remained constant over a range of osmotic pressures from 650 to 1,910 mosM (Kt, 7.8 to 15.5 mM). The Vmax, however, increased from 15 nmol/min/mg of dry weight in 0.5 M sucrose to 27 and 40 nmol/min/mg of dry weight in 0.5 M KCl and in 1.0 M KCl or NaCl, respectively. The efflux of proline from preloaded cells occurred rapidly when the osmotic pressure of the suspending buffer was lowered. PMID:1786048

  12. Improved bioavailability of dietary phenolic acids in whole grain barley and oat groat following fermentation with probiotic Lactobacillus acidophilus , Lactobacillus johnsonii , and Lactobacillus reuteri.

    PubMed

    Hole, Anastasia S; Rud, Ida; Grimmer, Stine; Sigl, Stefanie; Narvhus, Judith; Sahlstrøm, Stefan

    2012-06-27

    The aim of this study was to improve the bioavailability of the dietary phenolic acids in flours from whole grain barley and oat groat following fermentation with lactic acid bacteria (LAB) exhibiting high feruloyl esterase activity (FAE). The highest increase of free phenolic acids was observed after fermentation with three probiotic strains, Lactobacillus johnsonii LA1, Lactobacillus reuteri SD2112, and Lactobacillus acidophilus LA-5, with maximum increases from 2.55 to 69.91 μg g(-1) DM and from 4.13 to 109.42 μg g(-1) DM in whole grain barley and oat groat, respectively. Interestingly, higher amounts of bound phenolic acids were detected after both water treatment and LAB fermentation in whole grain barley, indicating higher bioaccessibility, whereas some decrease was detected in oat groat. To conclude, cereal fermentation with specific probiotic strains can lead to significant increase of free phenolic acids, thereby improving their bioavailability. PMID:22676388

  13. Effect of some nutritional and environmental parameters on the production of diacetyl and on starch consumption by Pediococcus pentosaceus and Lactobacillus acidophilus in submerged cultures.

    PubMed

    Escamilla, M L; Valdés, S E; Soriano, J; Tomasini, A

    2000-01-01

    Three series of 5-day submerged cultures with Pediococcus pentosaceus MITJ-10 and Lactobacillus acidophilus Hansen 1748 were carried out in starch-based media, and the effect of cultural factors on the changes of starch, diacetyl and amylase activity determined. In axenic cultures, Ped. pentosaceus MITJ-10 produced more diacetyl (63.27 mg l(-1)) by adding glucose, yeast extract and CaCO3 (P < 0.01), at 28 degrees C (P < 0.05); but more starch was consumed (18.4 g l(-1)) in the absence of glucose (P < 0.01). Lact. acidophilus Hansen 1748 consumed more starch (26.56 g l(-1)) at 28 degrees C, with CaCO3, glucose (P < 0.01) and yeast extract (P < 0.05); however, the amylolytic activity (10077U l(-1)) was favoured at 35 degrees C (P < 0.01). Little starch was consumed in mixed cultures due to the low pH; nevertheless, diacetyl content rose to 135.76 mg l(-1) at 32 degrees C (P < 0.01). Therefore, both studied strains might be useful to produce aromatic extensors from starchy substrates. These natural aromatic extensors are of interest to the food industry. PMID:10735253

  14. Characterization of a novel bile-inducible operon encoding a two-component regulatory system in Lactobacillus acidophilus.

    PubMed

    Pfeiler, Erika A; Azcarate-Peril, M Andrea; Klaenhammer, Todd R

    2007-07-01

    Lactobacillus acidophilus NCFM is an industrially important strain used extensively as a probiotic culture. Tolerance of the presence of bile is an attribute important to microbial survival in the intestinal tract. A whole-genome microarray was employed to examine the effects of bile on the global transcriptional profile of this strain, with the intention of elucidating genes contributing to bile tolerance. Genes involved in carbohydrate metabolism were generally induced, while genes involved in other aspects of cellular growth were mostly repressed. A 7-kb eight-gene operon encoding a two-component regulatory system (2CRS), a transporter, an oxidoreductase, and four hypothetical proteins was significantly upregulated in the presence of bile. Deletion mutations were constructed in six genes of the operon. Transcriptional analysis of the 2CRS mutants showed that mutation of the histidine protein kinase (HPK) had no effect on the induction of the operon, whereas the mutated response regulator (RR) showed enhanced induction when the cells were exposed to bile. These results indicate that the 2CRS plays a role in bile tolerance and that the operon it resides in is negatively controlled by the RR. Mutations in the transporter, the HPK, the RR, and a hypothetical protein each resulted in loss of tolerance of bile. Mutations in genes encoding another hypothetical protein and a putative oxidoreductase resulted in significant increases in bile tolerance. This functional analysis showed that the operon encoded proteins involved in both bile tolerance and bile sensitivity. PMID:17449631

  15. Lactobacillus acidophilus upregulates intestinal NHE3 expression and function

    PubMed Central

    Singh, Varsha; Raheja, Geetu; Borthakur, Alip; Kumar, Anoop; Gill, Ravinder K.; Alakkam, Anas; Malakooti, Jaleh

    2012-01-01

    A major mechanism of electroneutral NaCl absorption in the human ileum and colon involves coupling of Na+/H+ and Cl−/HCO3− exchangers. Disturbances in these mechanisms have been implicated in diarrheal conditions. Probiotics such as Lactobacillus have been indicated to be beneficial in the management of gastrointestinal disorders, including diarrhea. However, the molecular mechanisms underlying antidiarrheal effects of probiotics have not been fully understood. We have previously demonstrated Lactobacillus acidophilus (LA) to stimulate Cl−/HCO3− exchange activity via an increase in the surface levels and expression of the Cl−/HCO3− exchanger DRA in vitro and in vivo. However, the effects of LA on NHE3, the Na+/H+ exchanger involved in the coupled electroneutral NaCl absorption, are not known. Current studies were, therefore, undertaken to investigate the effects of LA on the function and expression of NHE3 and to determine the mechanisms involved. Treatment of Caco2 cells with LA or its conditioned culture supernatant (CS) for 8–24 h resulted in a significant increase in Na+/H+ exchange activity, mRNA, and protein levels of NHE3. LA-CS upregulation of NHE3 function and expression was also observed in SK-CO15 cells, a human colonic adenocarcinoma cell line. Additionally, LA treatment increased NHE3 promoter activity, suggesting involvement of transcriptional mechanisms. In vivo, mice gavaged with live LA showed significant increase in NHE3 mRNA and protein expression in the ileum and colonic regions. In conclusion, LA-induced increase in NHE3 expression may contribute to the upregulation of intestinal electrolyte absorption and might underlie the potential antidiarrheal effects of probiotics. PMID:23086913

  16. Potential for tyndalized Lactobacillus acidophilus as an effective component in moisturizing skin and anti-wrinkle products

    PubMed Central

    Im, A-Rang; Kim, Hui Seong; Hyun, Jin Won; Chae, Sungwook

    2016-01-01

    It is widely accepted that ultraviolet (UV) irradiation induces skin damage. In the present study, a UVB-induced hairless mouse model of skin photoaging was developed to determine whether tyndalized Lactobacillus acidophilus was able to significantly enhance the repair of photodamaged skin. To evaluate the effects of tyndalized L. acidophilus on UVB-induced skin-wrinkle formation in vivo, HR-1 hairless male mice were exposed to UVB radiation and orally administered tyndalized L. acidophilus. Compared with the control group, the UVB irradiation mice displayed a significant increase in transepidermal water loss and a reduction in skin hydration. In mice with UVB-induced photodamage, the effacement of the fine wrinkles by tyndalized L. acidophilus was correlated with dermal collagen synthesis, accompanied by histological changes. Furthermore, western blotting was performed to investigate the protein expression levels of matrix metalloproteinases (MMPs) and mitogen-activated protein kinase. Notably, orally administered tyndalized L. acidophilus reduced the expression levels of MMP-1 and MMP-9. Based upon the aforementioned results, it was determined that tyndalized L. acidophilus effectively inhibited the wrinkle formation induced by UVB irradiation, and that this may be attributed to the downregulation of MMPs. Therefore, tyndalized L. acidophilus may be considered a potential agent for preventing skin photoaging and wrinkle formation. PMID:27446272

  17. Lactobacillus acidophilus ATCC 4356 prevents atherosclerosis via inhibition of intestinal cholesterol absorption in apolipoprotein E-knockout mice.

    PubMed

    Huang, Ying; Wang, Jinfeng; Quan, Guihua; Wang, Xiaojun; Yang, Longfei; Zhong, Lili

    2014-12-01

    The objective of this study was to investigate the effect of Lactobacillus acidophilus ATCC 4356 on the development of atherosclerosis in apolipoprotein E-knockout (ApoE(-/-)) mice. Eight-week-old ApoE(-/-) mice were fed a Western diet with or without L. acidophilus ATCC 4356 daily for 16 weeks. L. acidophilus ATCC 4356 protected ApoE(-/-) mice from atherosclerosis by reducing their plasma cholesterol levels from 923 ± 44 to 581 ± 18 mg/dl, likely via a marked decrease in cholesterol absorption caused by modulation of Niemann-Pick C1-like 1 (NPC1L1). In addition, suppression of cholesterol absorption induced reverse cholesterol transport (RCT) in macrophages through the peroxisome proliferator-activated receptor/liver X receptor (PPAR/LXR) pathway. Fecal lactobacillus and bifidobacterium counts were significantly (P < 0.05) higher in the L. acidophilus ATCC 4356 treatment groups than in the control groups. Furthermore, L. acidophilus ATCC 4356 was detected in the rat small intestine, colon, and feces during the feeding trial. The bacterial levels remained high even after the administration of lactic acid bacteria had been stopped for 2 weeks. These results suggest that administration of L. acidophilus ATCC 4356 can protect against atherosclerosis through the inhibition of intestinal cholesterol absorption. Therefore, L. acidophilus ATCC 4356 may be a potential therapeutic material for preventing the progression of atherosclerosis. PMID:25261526

  18. Lactobacillus acidophilus ATCC 4356 Prevents Atherosclerosis via Inhibition of Intestinal Cholesterol Absorption in Apolipoprotein E-Knockout Mice

    PubMed Central

    Wang, Jinfeng; Quan, Guihua; Wang, Xiaojun; Yang, Longfei; Zhong, Lili

    2014-01-01

    The objective of this study was to investigate the effect of Lactobacillus acidophilus ATCC 4356 on the development of atherosclerosis in apolipoprotein E-knockout (ApoE−/−) mice. Eight-week-old ApoE−/− mice were fed a Western diet with or without L. acidophilus ATCC 4356 daily for 16 weeks. L. acidophilus ATCC 4356 protected ApoE−/− mice from atherosclerosis by reducing their plasma cholesterol levels from 923 ± 44 to 581 ± 18 mg/dl, likely via a marked decrease in cholesterol absorption caused by modulation of Niemann-Pick C1-like 1 (NPC1L1). In addition, suppression of cholesterol absorption induced reverse cholesterol transport (RCT) in macrophages through the peroxisome proliferator-activated receptor/liver X receptor (PPAR/LXR) pathway. Fecal lactobacillus and bifidobacterium counts were significantly (P < 0.05) higher in the L. acidophilus ATCC 4356 treatment groups than in the control groups. Furthermore, L. acidophilus ATCC 4356 was detected in the rat small intestine, colon, and feces during the feeding trial. The bacterial levels remained high even after the administration of lactic acid bacteria had been stopped for 2 weeks. These results suggest that administration of L. acidophilus ATCC 4356 can protect against atherosclerosis through the inhibition of intestinal cholesterol absorption. Therefore, L. acidophilus ATCC 4356 may be a potential therapeutic material for preventing the progression of atherosclerosis. PMID:25261526

  19. Dominance of Lactobacillus acidophilus in the Facultative Jejunal Lactobacillus Microbiota of Fistulated Beagles

    PubMed Central

    Tang, Yurui; Manninen, Titta J. K.

    2012-01-01

    Lactobacilli were isolated from jejunal chyme from five fistulated beagles. Cultivable lactobacilli varied from 104 to 108 CFU/ml. Seventy-four isolates were identified by partial 16S rRNA gene sequencing and differentiated by repetitive element PCR (Rep-PCR), Lactobacillus acidophilus was dominant, and nearly 80% of 54 isolates shared the same DNA fingerprint pattern. PMID:22843523

  20. Lactobacillus acidophilus: characterization of the species and application in food production.

    PubMed

    Anjum, Nazia; Maqsood, Shabana; Masud, Tariq; Ahmad, Asif; Sohail, Asma; Momin, Abdul

    2014-01-01

    L. acidophilus is a homofermentative, microaerophilic, short chain gram positive microorganism with rod morphology having its bacteriocins belonging to class II a. Several bacteriocins of L. acidophilus have been isolated and characterized. These are structurally similar, but their molecular weight varies as well as their spectrum of antimicrobial activity. They exhibit important technical properties, i.e., thermostability and retaining of activity at a wide pH range along with strong inhibitory actions against food spoilage and pathogenic bacteria make them an important class of biopreservatives. L. acidophilus can be added as an adjunct in many food fermentation processes contributing to unique taste, flavor, and texture. It also preserves the products by producing lactic acid and bacteriocins. A lot of new information regarding the bacteriocins of L. acidophilus has emerged during the last few years. In this review, an attempt has been made to summarize and discuss all the available information regarding the sources of bacteriocins production, their characteristics, and their antimicrobial action along with their application. PMID:24499153

  1. Combined effect of Lactobacillus acidophilus and β-cyclodextrin on serum cholesterol in pigs.

    PubMed

    Alonso, L; Fontecha, J; Cuesta, P

    2016-01-14

    A total of twenty-four Yorkshire gilt pigs of 6-7 weeks of age were used in a 2×2 factorial experiment to determine the individual and combined effects of the inclusion of two dietary factors (cholesterol rich, 3% β-cyclodextrin (BCD) and Lactobacillus acidophilus cultures) on total cholesterol and LDL-cholesterol levels in blood serum. Pigs were assigned randomly to treatment groups (n 6). Total serum cholesterol concentrations decreased after 3 weeks in all the experimental treatment groups, including diets with BCD, L. acidophilus or both. Similar trends were observed for serum LDL-cholesterol concentrations among the experimental treatments. No statistically significant differences from the control group were observed in either total serum cholesterol or LDL-cholesterol concentrations (P<0·05) for each of the individual treatment groups: BCD or L. acidophilus. However, significant differences in total serum cholesterol concentrations were observed when comparing the combined treatment group (BCD and L. acidophilus) with the control group, which consisted of a basal diet and sterile milk. The combined treatment group exhibited 17·9% lower total serum cholesterol concentration after 3 weeks. Similar significant differences were observed when comparing the combined effect experimental group with the control group after 3 weeks. The combined treatment group exhibited 27·9% lower serum LDL-cholesterol concentrations. PMID:26467089

  2. Bifidobacterium bifidum actively changes the gene expression profile induced by Lactobacillus acidophilus in murine dendritic cells.

    PubMed

    Weiss, Gudrun; Rasmussen, Simon; Nielsen Fink, Lisbeth; Jarmer, Hanne; Nøhr Nielsen, Birgit; Frøkiaer, Hanne

    2010-01-01

    Dendritic cells (DC) play a pivotal regulatory role in activation of both the innate as well as the adaptive immune system by responding to environmental microorganisms. We have previously shown that Lactobacillus acidophilus induces a strong production of the pro-inflammatory and Th1 polarizing cytokine IL-12 in DC, whereas bifidobacteria do not induce IL-12 but inhibit the IL-12 production induced by lactobacilli. In the present study, genome-wide microarrays were used to investigate the gene expression pattern of murine DC stimulated with Lactobacillus acidophilus NCFM and Bifidobacterium bifidum Z9. L. acidophilus NCFM strongly induced expression of interferon (IFN)-beta, other virus defence genes, and cytokine and chemokine genes related to the innate and the adaptive immune response. By contrast, B. bifidum Z9 up-regulated genes encoding cytokines and chemokines related to the innate immune response. Moreover, B. bifidum Z9 inhibited the expression of the Th1-promoting genes induced by L. acidophilus NCFM and had an additive effect on genes of the innate immune response and Th2 skewing genes. The gene encoding Jun dimerization protein 2 (JDP2), a transcription factor regulating the activation of JNK, was one of the few genes only induced by B. bifidum Z9. Neutralization of IFN-beta abrogated L. acidophilus NCFM-induced expression of Th1-skewing genes, and blocking of the JNK pathway completely inhibited the expression of IFN-beta. Our results indicate that B. bifidum Z9 actively inhibits the expression of genes related to the adaptive immune system in murine dendritic cells and that JPD2 via blocking of IFN-beta plays a central role in this regulatory mechanism. PMID:20548777

  3. Antagonistic activity of Lactobacillus acidophilus LB against intracellular Salmonella enterica serovar Typhimurium infecting human enterocyte-like Caco-2/TC-7 cells.

    PubMed

    Coconnier, M H; Liévin, V; Lorrot, M; Servin, A L

    2000-03-01

    To gain further insight into the mechanism by which lactobacilli develop antimicrobial activity, we have examined how Lactobacillus acidophilus LB inhibits the promoted cellular injuries and intracellular lifestyle of Salmonella enterica serovar Typhimurium SL1344 infecting the cultured, fully differentiated human intestinal cell line Caco-2/TC-7. We showed that the spent culture supernatant of strain LB (LB-SCS) decreases the number of apical serovar Typhimurium-induced F-actin rearrangements in infected cells. LB-SCS treatment efficiently decreased transcellular passage of S. enterica serovar Typhimurium. Moreover, LB-SCS treatment inhibited intracellular growth of serovar Typhimurium, since treated intracellular bacteria displayed a small, rounded morphology resembling that of resting bacteria. We also showed that LB-SCS treatment inhibits adhesion-dependent serovar Typhimurium-induced interleukin-8 production. PMID:10698785

  4. The influence of Lactobacillus acidophilus and bacitracin on layer performance of chickens and cholesterol content of plasma and egg yolk.

    PubMed

    Abdulrahim, S M; Haddadin, S Y; Hashlamoun, E A; Robinson, R K

    1996-05-01

    1. The influence of Lactobacillus acidophilus alone or in combination with zinc bacitracin on the performance of laying hens was monitored over a period of 4 months. 2. Lactobacillus acidophilus improved egg production, food conversion and reduced the cholesterol concentration in the eggs, but zinc bacitracin had no effect when administered alone. 3. In combination, bacitracin had an adverse effect on the otherwise beneficial activity of the culture. PMID:8773843

  5. Proteome reference map of Lactobacillus acidophilus NCFM and quantitative proteomics towards understanding the prebiotic action of lactitol.

    PubMed

    Majumder, Avishek; Sultan, Abida; Jersie-Christensen, Rosa R; Ejby, Morten; Schmidt, Bjarne Gregers; Lahtinen, Sampo J; Jacobsen, Susanne; Svensson, Birte

    2011-09-01

    Lactobacillus acidophilus NCFM is a probiotic bacterium adapted to survive in the gastrointestinal tract and with potential health benefits to the host. Lactitol is a synthetic sugar alcohol used as a sugar replacement in low calorie foods and selectively stimulating growth of L. acidophilus NCFM. In the present study the whole-cell extract proteome of L. acidophilus NCFM grown on glucose until late exponential phase was resolved by 2-DE (pH 3-7). A total of 275 unique proteins assigned to various physiological processes were identified from 650 spots. Differential 2-DE (DIGE) (pH 4-7) of L. acidophilus NCFM grown on glucose and lactitol, revealed 68 spots with modified relative intensity. Thirty-two unique proteins were identified in 41 of these spots changing 1.6-12.7-fold in relative abundance by adaptation of L. acidophilus NCFM to growth on lactitol. These proteins included β-galactosidase small subunit, galactokinase, galactose-1-phosphate uridylyltransferase and UDP-glucose-4-epimerase, which all are potentially involved in lactitol metabolism. This first comprehensive proteome analysis of L. acidophilus NCFM provides insights into protein abundance changes elicited by the prebiotic lactitol. PMID:21751373

  6. Impact of oral Lactobacillus acidophilus gavage on rooster seminal and cloacal Lactobacilli concentrations.

    PubMed

    Kiess, A S; Hirai, J H; Triplett, M D; Parker, H M; McDaniel, C D

    2016-08-01

    The use of antibiotics in poultry is being heavily scrutinized, therefore alternatives such as probiotics are being investigated. Lactobacilli spp. are a commonly used bacteria in formulating probiotics, and the addition of Lactobacilli to broiler diets has demonstrated increased growth rates, stimulated immune systems, and reduced pathogen loads in the gastro-intestinal tract ( GI: ) tract. However, previous research has shown that when rooster semen is directly exposed to Lactobacillus acidophilus (L. acidophilus) sperm quality is reduced. Therefore, the objective of the current study was to determine if oral administration of L. acidophilus increases the concentration of Lactobacilli in semen as well as the cloaca. A total of 30 roosters were used: 15 roosters were gavaged with 1X PBS (Control) and 15 roosters were gavaged with 10(7) cfu/mL of L. acidophilus (Treated). All roosters were gavaged for 14 consecutive days. Semen was collected on a 3 d interval, and cloacal swabs were collected on a 2 d interval, beginning on the first day prior to oral administration. Semen and cloacal swabs were serial diluted, and 100 μL of each dilution was then plated on Man, Rogosa, Sharpe ( MRS: ) agar plates. All plates were incubated for 48 h at 37°C under anaerobic conditions and counted. All Lactobacilli counts were first log transformed, then log transformed (day 0) pre-counts were subtracted from the log transformed day counts providing log differences for the analysis. Seminal Lactobacilli counts were not altered by treatments. However, the main effect of treatment (P = 0.026) for cloacal counts indicated that roosters gavaged with Lactobacilli yielded higher counts than the controls. Additionally, cloaca samples also demonstrated a treatment by day interaction trend (P = 0.082), where Lactobacilli was higher in the L. acidophilus gavaged roosters than the controls only on days 3, 5, 13, and 15. In conclusion, the addition of L. acidophilus to the male breeder diet

  7. Potential probiotic lactic acid bacteria Lactobacillus rhamnosus (HN001), Lactobacillus acidophilus (HN017) and Bifidobacterium lactis (HN019) do not degrade gastric mucin in vitro.

    PubMed

    Zhou, J S; Gopal, P K; Gill, H S

    2001-01-22

    The mucus layer (mucin) coating the surface of the gastrointestinal tract (GIT) plays an important role in the mucosal barrier system. Any damage or disturbance of this mucin layer will compromise the host's mucosal defence function. In the present study, the ability of three potential probiotic lactic acid bacteria (LAB) strains (Lactobacillus rhamnosus HN001, Lactobacillus acidophilus HN017, Bifidobacterium lactis HN019) to degrade mucin in vitro was evaluated, in order to assess their potential pathogenicity and local toxicity. The LAB strains were incubated in medium containing hog gastric mucin (HGM, 0.3%) at 37 degrees C for 48 h, following which any decrease in carbohydrate and protein concentration in the ethanol-precipitated portion of the culture medium was determined, using phenol-sulphuric acid and bicinchonic acid (BCA) protein assays, respectively. The change in molecular weight of mucin glycoproteins, following incubation with the test strains, was monitored by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). In order to expose any ability of the test strains to degrade mucin visually and more directly, the test strains were also cultured on agarose containing 0.3% HGM and incubated anaerobically for 72 h at 37 degrees C. No significant change in the carbohydrate or protein concentration in mucin substrates was found following incubation with the test strains. No mucin fragments were derived from the mucin suspension incubated with test strains, and no mucinolysis zone was identified on agarose. These results demonstrate that the potential probiotic LAB strains tested here were unable to degrade gastrointestinal mucin in vitro, which suggests that these novel probiotic candidates are likely to be non-invasive and non-toxic at the mucosal interface. PMID:11205957

  8. Stability of free and encapsulated Lactobacillus acidophilus ATCC 4356 in yogurt and in an artificial human gastric digestion system.

    PubMed

    Ortakci, F; Sert, S

    2012-12-01

    The objective of this study was to determine the effect of encapsulation on survival of probiotic Lactobacillus acidophilus ATCC 4356 (ATCC 4356) in yogurt and during artificial gastric digestion. Strain ATCC 4356 was added to yogurt either encapsulated in calcium alginate or in free form (unencapsulated) at levels of 8.26 and 9.47 log cfu/g, respectively, and the influence of alginate capsules (1.5 to 2.5mm) on the sensorial characteristics of yogurts was investigated. The ATCC 4356 strain was introduced into an artificial gastric solution consisting of 0.08 N HCl (pH 1.5) containing 0.2% NaCl or into artificial bile juice consisting of 1.2% bile salts in de Man, Rogosa, and Sharpe broth to determine the stability of the probiotic bacteria. When incubated for 2h in artificial gastric juice, the free ATCC 4356 did not survive (reduction of >7 log cfu/g). We observed, however, greater survival of encapsulated ATCC 4356, with a reduction of only 3 log cfu/g. Incubation in artificial bile juice (6 h) did not significantly affect the viability of free or encapsulated ATCC 4356. Moreover, statistically significant reductions (~1 log cfu/g) of both free and encapsulated ATCC 4356 were observed during 4-wk refrigerated storage of yogurts. The addition of probiotic cultures in free or alginate-encapsulated form did not significantly affect appearance/color or flavor/odor of the yogurts. However, significant deficiencies were found in body/texture of yogurts containing encapsulated ATCC 4356. We concluded that incorporation of free and encapsulated probiotic bacteria did not substantially change the overall sensory properties of yogurts, and encapsulation in alginate using the extrusion method greatly enhanced the survival of probiotic bacteria against an artificial human gastric digestive system. PMID:23021757

  9. Microencapsulation of Bifidobacterium animalis subsp. lactis and Lactobacillus acidophilus in cocoa butter using spray chilling technology

    PubMed Central

    Pedroso, D.L.; Dogenski, M.; Thomazini, M.; Heinemann, R.J.B.; Favaro-Trindade, C.S.

    2013-01-01

    In the present study, the cells of Bifidobacterium animalis subsp. lactis (BI-01) and Lactobacillus acidophilus (LAC-04) were encapsulated in cocoa butter using spray-chilling technology. Survival assays were conducted to evaluate the resistance of the probiotics to the spray-chilling process, their resistance to the simulated gastric and intestinal fluids (SGF and SIF), and their stability during 90 days of storage. The viability of the cells was not affected by microencapsulation. The free and encapsulated cells of B. animalis subsp. lactis were resistant to both SGF and SIF. The micro-encapsulated cells of L. acidophilus were more resistant to SGF and SIF than the free cells; the viability of the encapsulated cells was enhanced by 67%, while the free cells reached the detection limit of the method (103 CFU/g). The encapsulated probiotics were unstable when they were stored at 20 °C. The population of encapsulated L. acidophilus decreased drastically when they were stored at 7 °C; only 20% of cells were viable after 90 days of storage. The percentage of viable cells of the encapsulated B. animalis subsp.lactis, however, was 72% after the same period of storage. Promising results were obtained when the microparticles were stored at −18 °C; the freeze granted 90 days of shelf life to the encapsulated cells. These results suggest that the spray-chilling process using cocoa butter as carrier protects L. acidophilus from gastrointestinal fluids. However, the viability of the cells during storage must be improved. PMID:24516445

  10. Whole-cell detection of live lactobacillus acidophilus on aptamer-decorated porous silicon biosensors.

    PubMed

    Urmann, K; Arshavsky-Graham, S; Walter, J G; Scheper, T; Segal, E

    2016-09-21

    This work describes the design of optical aptamer-based porous silicon (PSi) biosensors for the direct capture of Lactobacillus acidophilus. Aptamers are oligonucleotides (single-stranded DNA or RNA) that can bind their targets with high affinity and specificity, making them excellent recognition elements for biosensing applications. Herein, aptamer Hemag1P, which specifically targets the important probiotic L. acidophilus, was utilized for direct bacteria capture onto oxidized PSi Fabry-Pérot thin films. Monitoring changes in the reflectivity spectrum (using reflective interferometric Fourier transform spectroscopy) allows for bacteria detection in a label-free, simple and rapid manner. The performance of the biosensor was optimized by tuning the PSi nanostructure, its optical properties, as well as the immobilization density of the aptamer. We demonstrate the high selectivity and specificity of this simple "direct-capture" biosensing scheme and show its ability to distinguish between live and dead bacteria. The resulting biosensor presents a robust and rapid method for the specific detection of live L. acidophilus at concentrations relevant for probiotic products and as low as 10(6) cells per mL. Rapid monitoring of probiotic bacteria is crucial for quality, purity and safety control as the use of probiotics in functional foods and pharmaceuticals is becoming increasingly popular. PMID:27381045

  11. Immunoregulatory effects on Caco-2 cells and mice of exopolysaccharides isolated from Lactobacillus acidophilus NCFM.

    PubMed

    Li, Li; Jiang, Yu-Jun; Yang, Xiang-Yi; Liu, Ying; Wang, Jin-Yu; Man, Chao-Xin

    2014-12-01

    On the basis of our previous results on potential immunoregulation of Lactobacillus acidophilus NCFM, the immunoregulatory effects of exopolysaccharides (EPS) isolated from L. acidophilus NCFM and their regulating mechanisms are further investigated in the current research. Stimulated by EPS preparations, four immune-related genes in the human colorectal adenocarcinoma cell line Caco-2 cells, namely, interleukin-1α (IL-1α), chemokine C-C motif 2 (CCL2), tumor necrosis factor α (TNF-α), and pentraxin 3 (PTX3), first showed an increase at 2-4 h, peaked at 4 h, and then decreased at 4-12 h. Similar trends were observed in vivo: four genes showed transient expression (highest on the 4th day) in the cecum and colon of mice. Meanwhile, the organ coefficient, clearance index and phagocytic index all significantly increased with time extension and dose increase of EPS stimulation. EPS triggered NF-κB and p38 mitogen-activated protein kinase (p38 MAPK) signaling pathways in Caco-2 cells, and the activated pathways initiated the genes expression. EPS compounds from L. acidophilus NCFM may play an important role in host immunoregulation and might be applied as a new type of immunoregulatory agent in functional foods. PMID:25340590

  12. Regulation of induced colonic inflammation by Lactobacillus acidophilus deficient in lipoteichoic acid.

    PubMed

    Mohamadzadeh, Mansour; Pfeiler, Erika A; Brown, Jeffrey B; Zadeh, Mojgan; Gramarossa, Matthew; Managlia, Elizabeth; Bere, Praveen; Sarraj, Bara; Khan, Mohammad W; Pakanati, Krishna Chaitanya; Ansari, M Javeed; O'Flaherty, Sarah; Barrett, Terrence; Klaenhammer, Todd R

    2011-03-15

    Imbalance in the regulatory immune mechanisms that control intestinal cellular and bacterial homeostasis may lead to induction of the detrimental inflammatory signals characterized in humans as inflammatory bowel disease. Induction of proinflammatory cytokines (i.e., IL-12) induced by dendritic cells (DCs) expressing pattern recognition receptors may skew naive T cells to T helper 1 polarization, which is strongly implicated in mucosal autoimmunity. Recent studies show the ability of probiotic microbes to treat and prevent numerous intestinal disorders, including Clostridium difficile-induced colitis. To study the molecular mechanisms involved in the induction and repression of intestinal inflammation, the phosphoglycerol transferase gene that plays a key role in lipoteichoic acid (LTA) biosynthesis in Lactobacillus acidophilus NCFM (NCK56) was deleted. The data show that the L. acidophilus LTA-negative in LTA (NCK2025) not only down-regulated IL-12 and TNFα but also significantly enhanced IL-10 in DCs and controlled the regulation of costimulatory DC functions, resulting in their inability to induce CD4(+) T-cell activation. Moreover, treatment of mice with NCK2025 compared with NCK56 significantly mitigated dextran sulfate sodium and CD4(+)CD45RB(high)T cell-induced colitis and effectively ameliorated dextran sulfate sodium-established colitis through a mechanism that involves IL-10 and CD4(+)FoxP3(+) T regulatory cells to dampen exaggerated mucosal inflammation. Directed alteration of cell surface components of L. acidophilus NCFM establishes a potential strategy for the treatment of inflammatory intestinal disorders. PMID:21282652

  13. Lactobacillus acidophilus K301 Inhibits Atherogenesis via Induction of 24 (S), 25-Epoxycholesterol-Mediated ABCA1 and ABCG1 Production and Cholesterol Efflux in Macrophages.

    PubMed

    Hong, Yi-Fan; Kim, Hangeun; Kim, Hye Sun; Park, Woo Jung; Kim, Joo-Yun; Chung, Dae Kyun

    2016-01-01

    Lactobacillus acidophilus species are well-known probiotics with the beneficial activity of regulating cholesterol levels. In this study, we showed that L. acidophilus K301 reduced the level of cholesterol through reverse transport in macrophages. L. acidophilus K301 upregulated the mRNA and protein levels of genes such as ATP-binding cassette A1 (ABCA1) and ATP-binding cassette G1 (ABCG1) under the control of liver X receptor (LXR), resulting in increased apoA-I-dependent cholesterol efflux in phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 cells. L. acidophilus K301 induced both ABCA1 and ABCG1 through the endogenous LXR agonist 24(S), 25-epoxcycholesterol, which is synthesized by intracellular cholesterol synthetic pathways. In vivo studies using L. acidophilus K301-treated ApoE-/- mice showed reduced accumulation of lipoproteins in the arterial lumen. The inhibitory effects of L. acidophilus K301 on accumulation of lipoprotein in atherosclerotic plaques were mediated by the induction of squalene reductase (SQLE) and oxidosqualene cyclase (OSC) and resulted in ABCA1-mediated cholesterol efflux. Taken together, our findings revealed that Lactobacillus acidophilus K301 regulates the expression of genes related to cholesterol reverse transport via the induction of endogenous LXR agonist, suggesting the therapeutic potential of Lactobacillus acidophilus K301 as an anti-atherosclerotic agent. PMID:27120199

  14. Lactobacillus acidophilus K301 Inhibits Atherogenesis via Induction of 24 (S), 25-Epoxycholesterol-Mediated ABCA1 and ABCG1 Production and Cholesterol Efflux in Macrophages

    PubMed Central

    Kim, Hye Sun; Park, Woo Jung; Kim, Joo-Yun; Chung, Dae Kyun

    2016-01-01

    Lactobacillus acidophilus species are well-known probiotics with the beneficial activity of regulating cholesterol levels. In this study, we showed that L. acidophilus K301 reduced the level of cholesterol through reverse transport in macrophages. L. acidophilus K301 upregulated the mRNA and protein levels of genes such as ATP-binding cassette A1 (ABCA1) and ATP-binding cassette G1 (ABCG1) under the control of liver X receptor (LXR), resulting in increased apoA-I-dependent cholesterol efflux in phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 cells. L. acidophilus K301 induced both ABCA1 and ABCG1 through the endogenous LXR agonist 24(S), 25-epoxcycholesterol, which is synthesized by intracellular cholesterol synthetic pathways. In vivo studies using L. acidophilus K301-treated ApoE-/- mice showed reduced accumulation of lipoproteins in the arterial lumen. The inhibitory effects of L. acidophilus K301 on accumulation of lipoprotein in atherosclerotic plaques were mediated by the induction of squalene reductase (SQLE) and oxidosqualene cyclase (OSC) and resulted in ABCA1-mediated cholesterol efflux. Taken together, our findings revealed that Lactobacillus acidophilus K301 regulates the expression of genes related to cholesterol reverse transport via the induction of endogenous LXR agonist, suggesting the therapeutic potential of Lactobacillus acidophilus K301 as an anti-atherosclerotic agent. PMID:27120199

  15. A new record of Chironomus (Chironomus) acidophilus Keyl (Diptera, Chironomidae) from the Uzon volcanic caldera (Kronotsky Reserve, Kamchatka Peninsula, Russia), its karyotype, ecology and biology.

    PubMed

    Orel, Oksana V; Lobkova, Ludmila E; Zhirov, Sergey V; Petrova, Ninel A

    2015-01-01

    Morphology, cytology, ecology and biology of Holarctic Chironomus (Chironomus) acidophilus Keyl, 1960 (Diptera, Chironomidae) was examined from material collected in the geothermal Vosmerka Lake (pH=2.0-2.5). An illustrated redescription of C. acidophilus is given on the basis of adult males reared from field-collected pupae, and of simultaneously collected larvae. Additional larvae belonging to the pseudothummi-complex were identified as C. acidophilus on the basis of their karyotype. The karyotype of C. acidophilus (2n=8) and detailed mapping of the 4 chromosome arms A, E, D and F are provided. The population of C. acidophilus from Kamchatka was found to be karyologically monomorphic. Information on distribution and ecology of C. acidophilus from Vosmerka Lake (total mineralization 1583.5 mg/l) is also given. Chironomus acidophilus is the only species of aquatic insects recorded in this lake. Lack of competition and a richness of food resources contribute to the high abundance (35161 ind./m2) and biomass (11.342 g/m2) of the larvae of C. acidophilus in Vosmerka Lake. PMID:26249988

  16. Lactobacillus acidophilus induces cytokine and chemokine production via NF-κB and p38 mitogen-activated protein kinase signaling pathways in intestinal epithelial cells.

    PubMed

    Jiang, Yujun; Lü, Xuena; Man, Chaoxin; Han, Linlin; Shan, Yi; Qu, Xingguang; Liu, Ying; Yang, Shiqin; Xue, Yuqing; Zhang, Yinghua

    2012-04-01

    Intestinal epithelial cells can respond to certain bacteria by producing an array of cytokines and chemokines which are associated with host immune responses. Lactobacillus acidophilus NCFM is a characterized probiotic, originally isolated from human feces. This study aimed to test the ability of L. acidophilus NCFM to stimulate cytokine and chemokine production in intestinal epithelial cells and to elucidate the mechanisms involved in their upregulation. In experiments using intestinal epithelial cell lines and mouse models, we observed that L. acidophilus NCFM could rapidly but transiently upregulate a number of effector genes encoding cytokines and chemokines such as interleukin 1α (IL-1α), IL-1β, CCL2, and CCL20 and that cytokines showed lower expression levels with L. acidophilus NCFM treatment than chemokines. Moreover, L. acidophilus NCFM could activate a pathogen-associated molecular pattern receptor, Toll-like receptor 2 (TLR2), in intestinal epithelial cell lines. The phosphorylation of NF-κB p65 and p38 mitogen-activated protein kinase (MAPK) in intestinal epithelial cell lines was also enhanced by L. acidophilus NCFM. Furthermore, inhibitors of NF-κB (pyrrolidine dithiocarbamate [PDTC]) and p38 MAPK (SB203580) significantly reduced cytokine and chemokine production in the intestinal epithelial cell lines stimulated by L. acidophilus NCFM, suggesting that both NF-κB and p38 MAPK signaling pathways were important for the production of cytokines and chemokines induced by L. acidophilus NCFM. PMID:22357649

  17. Lactobacillus acidophilus CL1285, Lactobacillus casei LBC80R, and Lactobacillus rhamnosus CLR2 (Bio-K+): Characterization, Manufacture, Mechanisms of Action, and Quality Control of a Specific Probiotic Combination for Primary Prevention of Clostridium difficile Infection.

    PubMed

    Auclair, Julie; Frappier, Martin; Millette, Mathieu

    2015-05-15

    A specific probiotic formulation composed of Lactobacillus acidophilus CL1285, Lactobacillus casei LBC80R, and Lactobacillus rhamnosus CLR2 (Bio-K+) has been marketed in North America since 1996. The strains and the commercial products have been evaluated for safety, identity, gastrointestinal survival, and stability throughout shelf life. The capacity of both the fermented beverages and the capsules to reduce incidences of antibiotic-associated diarrhea and Clostridium difficile infection (CDI) has been demonstrated in human clinical trials. Individual strains and the finished products have shown antimicrobial activity against C. difficile and toxin A/B neutralization capacity in vitro. The use of this specific probiotic formulation as part of a bundle of preventive measures to control CDI in healthcare settings is discussed. PMID:25922399

  18. Identification of extracellular surface-layer associated proteins in Lactobacillus acidophilus NCFM

    PubMed Central

    Johnson, Brant; Selle, Kurt; O’Flaherty, Sarah; Goh, Yong Jun

    2013-01-01

    Bacterial surface (S-) layers are crystalline arrays of self-assembling, proteinaceous subunits called S-layer proteins (Slps), with molecular masses ranging from 40 to 200 kDa. The S-layer-forming bacterium Lactobacillus acidophilus NCFM expresses three major Slps: SlpA (46 kDa), SlpB (47 kDa) and SlpX (51 kDa). SlpA has a demonstrated role in adhesion to Caco-2 intestinal epithelial cells in vitro, and has been shown to modulate dendritic cell (DC) and T-cell functionalities with murine DCs. In this study, a modification of a standard lithium chloride S-layer extraction revealed 37 proteins were solubilized from the S-layer wash fraction. Of these, 30 have predicted cleavage sites for secretion, 24 are predicted to be extracellular, six are lipid-anchored, three have N-terminal hydrophobic membrane spanning regions and four are intracellular, potentially moonlighting proteins. Some of these proteins, designated S-layer associated proteins (SLAPs), may be loosely associated with or embedded within the bacterial S-layer complex. Lba-1029, a putative SLAP gene, was deleted from the chromosome of L. acidophilus. Phenotypic characterization of the deletion mutant demonstrated that the SLAP LBA1029 contributes to a pro-inflammatory TNF-α response from murine DCs. This study identified extracellular proteins and putative SLAPs of L. acidophilus NCFM using LC-MS/MS. SLAPs appear to impart important surface display features and immunological properties to microbes that are coated by S-layers. PMID:24002751

  19. Lactobacillus acidophilus CRL 1014 improved “gut health” in the SHIME® reactor

    PubMed Central

    2013-01-01

    Background How to maintain “gut health” is a goal for scientists throughout the world. Therefore, microbiota management models for testing probiotics, prebiotics, and synbiotics have been developed. Methods The SHIME® model was used to study the effect of Lactobacillus acidophilus 1014 on the fermentation pattern of the colon microbiota. Initially, an inoculum prepared from human feces was introduced into the reactor vessels and stabilized over 2-wk using a culture medium. This stabilization period was followed by a 2-wk control period during which the microbiota was monitored. The microbiota was then subjected to a 4-wk treatment period by adding 5 mL of sterile peptone water with L. acidophilus CRL1014 at the concentration of 108 CFU/mL to vessel one (the stomach compartment). Plate counts, Denaturing Gradient Gel Electrophoresis (DGGE), short-chain fatty acid (SCFA) and ammonium analyses were carried out for monitoring of the microbial community from the colon compartments. Results A significant increase (p < 0.01) in the Lactobacillus spp. and Bifidobacterium spp. populations was observed during the treatment period. The DGGE obtained showed changes in the lactobacilli community from the colon compartments of the SHIME® reactor. The (SCFA) concentration increased (p < 0.01) during the treatment period, due mainly to significant increased levels of acetic, butyric, and propionic acids. However, ammonium concentrations decreased during the same period (p < 0.01). Conclusions This study showed the beneficial influence of L. acidophilus CRL 1014 on microbial metabolism and lactobacilli community composition for improving human health. PMID:23758634

  20. Identification of extracellular surface-layer associated proteins in Lactobacillus acidophilus NCFM.

    PubMed

    Johnson, Brant; Selle, Kurt; O'Flaherty, Sarah; Goh, Yong Jun; Klaenhammer, Todd

    2013-11-01

    Bacterial surface (S-) layers are crystalline arrays of self-assembling, proteinaceous subunits called S-layer proteins (Slps), with molecular masses ranging from 40 to 200 kDa. The S-layer-forming bacterium Lactobacillus acidophilus NCFM expresses three major Slps: SlpA (46 kDa), SlpB (47 kDa) and SlpX (51 kDa). SlpA has a demonstrated role in adhesion to Caco-2 intestinal epithelial cells in vitro, and has been shown to modulate dendritic cell (DC) and T-cell functionalities with murine DCs. In this study, a modification of a standard lithium chloride S-layer extraction revealed 37 proteins were solubilized from the S-layer wash fraction. Of these, 30 have predicted cleavage sites for secretion, 24 are predicted to be extracellular, six are lipid-anchored, three have N-terminal hydrophobic membrane spanning regions and four are intracellular, potentially moonlighting proteins. Some of these proteins, designated S-layer associated proteins (SLAPs), may be loosely associated with or embedded within the bacterial S-layer complex. Lba-1029, a putative SLAP gene, was deleted from the chromosome of L. acidophilus. Phenotypic characterization of the deletion mutant demonstrated that the SLAP LBA1029 contributes to a pro-inflammatory TNF-α response from murine DCs. This study identified extracellular proteins and putative SLAPs of L. acidophilus NCFM using LC-MS/MS. SLAPs appear to impart important surface display features and immunological properties to microbes that are coated by S-layers. PMID:24002751

  1. Lactobacillus acidophilus supplementation in human subjects and their resistance to enterotoxigenic Escherichia coli infection.

    PubMed

    Ouwehand, A C; ten Bruggencate, S J M; Schonewille, A J; Alhoniemi, E; Forssten, S D; Bovee-Oudenhoven, I M J

    2014-02-01

    To assess the effect of Lactobacillus acidophilus (American Type Culture Collection (ATCC) 700396) on enterotoxigenic Escherichia coli (ETEC) infection, in the present study, a parallel, double-blind, placebo-controlled 4-week intervention was performed in healthy males. The subjects largely consumed their habitual diet, but had to abstain from consuming dairy foods generally high in Ca. The subjects were randomised into the L. acidophilus (dose 10⁹ colony-forming units twice daily; n 20) or the placebo (n 19) group. After an adaptation period of 2 weeks, the subjects were orally infected with a live, but attenuated, ETEC vaccine, able to induce mild, short-lived symptoms. Before and after the challenge, the subjects recorded stool consistency, bowel habits, and frequency and severity of gastrointestinal complaints. The ETEC challenge led to a significant increase in faecal output on the 2nd day and a concomitant increase in Bristol stool scale scores. Likewise, abdominal pain, bloating, flatulence, fever, headache and nausea peaked 1 d after the oral challenge. The concentrations of faecal calprotectin and IgA peaked 2 d after and that of serum IgM peaked 9 and 15 d after the oral challenge. The concentrations of serum IgA and IgG were unaffected. The ETEC challenge led to a reduction in the number of Bacteroides-Prevotella, Bifidobacterium, Clostridium cluster XIVab and total faecal bacteria. Probiotic treatment was associated with a larger increase in Bristol stool scale scores and more fever, headache and nausea after the ETEC challenge compared with the placebo treatment. These differences were, however, small and with substantial variation within the groups. Oral application of an attenuated live ETEC vaccine provides a useful model for food-borne infections. Supplementation with L. acidophilus ATCC 700396, however, was ineffective in reducing ETEC infection symptoms in healthy men. PMID:23930950

  2. The growth of Gardnerella vaginalis and Lactobacillus acidophilus in Sorbarod biofilms.

    PubMed

    Muli, F W; Struthers, J K

    1998-05-01

    Sorbarod biofilms were investigated for their suitability in establishing continuous culture biofilms for the study of bacterial vaginosis. Two important organisms in the condition, Gardnerella vaginalis and Lactobacillus acidophilus, were studied. In contrast to growth in broth culture, both organisms were maintained for at least 96 h in a steady state on the biofilms. With G. vaginalis, the haemolytic activity was consistently maintained in the biofilms in contrast to short-term activity in broth culture which matched the bacterial titre. The simple Sorbarod system appears to be suitable for studying the growth conditions of bacteria in continuous culture and has potential for investigating interactions between micro-organisms. PMID:9879940

  3. Microencapsulation of Lactobacillus acidophilus NCFM using polymerized whey proteins as wall material.

    PubMed

    Jiang, Yujun; Zheng, Zhe; Zhang, Tiehua; Hendricks, Gregory; Guo, Mingruo

    2016-09-01

    Survivability of probiotics in foods is essential for developing functional food containing probiotics. We investigated polymerized whey protein (PWP)-based microencapsulation process which is developed for protecting probiotics like Lactobacillus acidophilus NCFM and compared with the method using sodium alginate (SA). The entrapment rate was 89.3 ± 4.8% using PWP, while it was 73.2 ± 1.4% for SA. The microencapsulated NCFM by PWP and SA were separately subjected to digestion juices and post-fermentation storage of fermented cows' and goats' milk using the encapsulated culture. The log viable count of NCFM in PWP-based microencapsulation was 4.56, compared with that of 4.26 in SA-based ones and 3.13 for free culture. Compared with using SA as wall material, PWP was more effective in protecting probiotic. Microencapsulation of L. acidophilus NCFM using PWP as wall material can be exploited in the development of fermented dairy products with better survivability of probiotic organism. PMID:27309796

  4. Control of cell morphology of probiotic Lactobacillus acidophilus for enhanced cell stability during industrial processing.

    PubMed

    Senz, Martin; van Lengerich, Bernhard; Bader, Johannes; Stahl, Ulf

    2015-01-01

    The viability of bacteria during industrial processing is an essential quality criterion for bacterial preparations, such as probiotics and starter cultures. Therefore, producing stable microbial cultures during proliferation is of great interest. A strong correlation between the culture medium and cellular morphology was observed for the lactic acid bacterium Lactobacillus acidophilus NCFM, which is commonly used in the dairy industry as a probiotic supplement and as a starter culture. The cell shapes ranged from single short rods to long filamentous rods. The culture medium composition could control this phenomenon of pleomorphism, especially the use of peptone in combination with an adequate heating of the medium during preparation. Furthermore, we observed a correlation between the cell size and stability of the microorganisms during industrial processing steps, such as freeze-drying, extrusion encapsulation and storage following dried preparations. The results revealed that short cells are more stable than long cells during each of the industrially relevant processing steps. As demonstrated for L. acidophilus NCFM, the adaptation of the medium composition and optimized medium preparation offer the possibility to increase the concentration of viable cells during up- and survival rate during down-stream processing. PMID:25305442

  5. A functional glycogen biosynthesis pathway in Lactobacillus acidophilus: expression and analysis of the glg operon

    PubMed Central

    Goh, Yong Jun; Klaenhammer, Todd R

    2013-01-01

    Glycogen metabolism contributes to energy storage and various physiological functions in some prokaryotes, including colonization persistence. A role for glycogen metabolism is proposed on the survival and fitness of Lactobacillus acidophilus, a probiotic microbe, in the human gastrointestinal environment. L. acidophilus NCFM possesses a glycogen metabolism (glg) operon consisting of glgBCDAP-amy-pgm genes. Expression of the glg operon and glycogen accumulation were carbon source- and growth phase-dependent, and were repressed by glucose. The highest intracellular glycogen content was observed in early log-phase cells grown on trehalose, which was followed by a drastic decrease of glycogen content prior to entering stationary phase. In raffinose-grown cells, however, glycogen accumulation gradually declined following early log phase and was maintained at stable levels throughout stationary phase. Raffinose also induced an overall higher temporal glg expression throughout growth compared with trehalose. Isogenic ΔglgA (glycogen synthase) and ΔglgB (glycogen-branching enzyme) mutants are glycogen-deficient and exhibited growth defects on raffinose. The latter observation suggests a reciprocal relationship between glycogen synthesis and raffinose metabolism. Deletion of glgB or glgP (glycogen phosphorylase) resulted in defective growth and increased bile sensitivity. The data indicate that glycogen metabolism is involved in growth maintenance, bile tolerance and complex carbohydrate utilization in L. acidophilus. PMID:23879596

  6. Transcriptional analysis of prebiotic uptake and catabolism by Lactobacillus acidophilus NCFM.

    PubMed

    Andersen, Joakim Mark; Barrangou, Rodolphe; Hachem, Maher Abou; Lahtinen, Sampo J; Goh, Yong-Jun; Svensson, Birte; Klaenhammer, Todd R

    2012-01-01

    The human gastrointestinal tract can be positively modulated by dietary supplementation of probiotic bacteria in combination with prebiotic carbohydrates. Here differential transcriptomics and functional genomics were used to identify genes in Lactobacillus acidophilus NCFM involved in the uptake and catabolism of 11 potential prebiotic compounds consisting of α- and β-linked galactosides and glucosides. These oligosaccharides induced genes encoding phosphoenolpyruvate-dependent sugar phosphotransferase systems (PTS), galactoside pentose hexuronide (GPH) permease, and ATP-binding cassette (ABC) transporters. PTS systems were upregulated primarily by di- and tri-saccharides such as cellobiose, isomaltose, isomaltulose, panose and gentiobiose, while ABC transporters were upregulated by raffinose, Polydextrose, and stachyose. A single GPH transporter was induced by lactitol and galactooligosaccharides (GOS). The various transporters were associated with a number of glycoside hydrolases from families 1, 2, 4, 13, 32, 36, 42, and 65, involved in the catabolism of various α- and β-linked glucosides and galactosides. Further subfamily specialization was also observed for different PTS-associated GH1 6-phospho-β-glucosidases implicated in the catabolism of gentiobiose and cellobiose. These findings highlight the broad oligosaccharide metabolic repertoire of L. acidophilus NCFM and establish a platform for selection and screening of both probiotic bacteria and prebiotic compounds that may positively influence the gastrointestinal microbiota. PMID:23028535

  7. A functional glycogen biosynthesis pathway in Lactobacillus acidophilus: expression and analysis of the glg operon.

    PubMed

    Goh, Yong Jun; Klaenhammer, Todd R

    2013-09-01

    Glycogen metabolism contributes to energy storage and various physiological functions in some prokaryotes, including colonization persistence. A role for glycogen metabolism is proposed on the survival and fitness of Lactobacillus acidophilus, a probiotic microbe, in the human gastrointestinal environment. L. acidophilus NCFM possesses a glycogen metabolism (glg) operon consisting of glgBCDAP-amy-pgm genes. Expression of the glg operon and glycogen accumulation were carbon source- and growth phase-dependent, and were repressed by glucose. The highest intracellular glycogen content was observed in early log-phase cells grown on trehalose, which was followed by a drastic decrease of glycogen content prior to entering stationary phase. In raffinose-grown cells, however, glycogen accumulation gradually declined following early log phase and was maintained at stable levels throughout stationary phase. Raffinose also induced an overall higher temporal glg expression throughout growth compared with trehalose. Isogenic ΔglgA (glycogen synthase) and ΔglgB (glycogen-branching enzyme) mutants are glycogen-deficient and exhibited growth defects on raffinose. The latter observation suggests a reciprocal relationship between glycogen synthesis and raffinose metabolism. Deletion of glgB or glgP (glycogen phosphorylase) resulted in defective growth and increased bile sensitivity. The data indicate that glycogen metabolism is involved in growth maintenance, bile tolerance and complex carbohydrate utilization in L. acidophilus. PMID:23879596

  8. Characterization of the tre locus and analysis of trehalose cryoprotection in Lactobacillus acidophilus NCFM.

    PubMed

    Duong, Tri; Barrangou, Rodolphe; Russell, W Michael; Klaenhammer, Todd R

    2006-02-01

    Freezing and lyophilization are common methods used for preservation and storage of microorganisms during the production of concentrated starter cultures destined for industrial fermentations or product formulations. The compatible solute trehalose has been widely reported to protect bacterial, yeast and animal cells against a variety of environmental stresses, particularly freezing and dehydration. Analysis of the Lactobacillus acidophilus NCFM genome revealed a putative trehalose utilization locus consisting of a transcriptional regulator, treR; a trehalose phosphoenolpyruvate transferase system (PTS) transporter, treB; and a trehalose-6-phosphate hydrolase, treC. The objective of this study was to characterize the tre locus in L. acidophilus and determine whether or not intracellular uptake of trehalose contributes to cryoprotection. Cells subjected to repeated freezing and thawing cycles were monitored for survival in the presence of various concentrations of trehalose. At 20% trehalose a 2-log increase in survival was observed. The trehalose PTS transporter and trehalose hydrolase were disrupted by targeted plasmid insertions. The resulting mutants were unable to grow on trehalose, indicating that both trehalose transport into the cell via a PTS and hydrolysis via a trehalose-6-phosphate hydrolase were necessary for trehalose fermentation. Trehalose uptake was found to be significantly reduced in the transporter mutant but unaffected in the hydrolase mutant. Additionally, the cryoprotective effect of trehalose was reduced in these mutants, suggesting that intracellular transport and hydrolysis contribute significantly to cryoprotection. PMID:16461669

  9. Transcriptional and functional analysis of galactooligosaccharide uptake by lacS in Lactobacillus acidophilus.

    PubMed

    Andersen, Joakim M; Barrangou, Rodolphe; Abou Hachem, Maher; Lahtinen, Sampo; Goh, Yong Jun; Svensson, Birte; Klaenhammer, Todd R

    2011-10-25

    Probiotic microbes rely on their ability to survive in the gastrointestinal tract, adhere to mucosal surfaces, and metabolize available energy sources from dietary compounds, including prebiotics. Genome sequencing projects have proposed models for understanding prebiotic catabolism, but mechanisms remain to be elucidated for many prebiotic substrates. Although β-galactooligosaccharides (GOS) are documented prebiotic compounds, little is known about their utilization by lactobacilli. This study aimed to identify genetic loci in Lactobacillus acidophilus NCFM responsible for the transport and catabolism of GOS. Whole-genome oligonucleotide microarrays were used to survey the differential global transcriptome during logarithmic growth of L. acidophilus NCFM using GOS or glucose as a sole source of carbohydrate. Within the 16.6-kbp gal-lac gene cluster, lacS, a galactoside-pentose-hexuronide permease-encoding gene, was up-regulated 5.1-fold in the presence of GOS. In addition, two β-galactosidases, LacA and LacLM, and enzymes in the Leloir pathway were also encoded by genes within this locus and up-regulated by GOS stimulation. Generation of a lacS-deficient mutant enabled phenotypic confirmation of the functional LacS permease not only for the utilization of lactose and GOS but also lactitol, suggesting a prominent role of LacS in the metabolism of a broad range of prebiotic β-galactosides, known to selectively modulate the beneficial gut microbiota. PMID:22006318

  10. Physicochemical and hygienic effects of Lactobacillus acidophilus in Iranian white cheese

    PubMed Central

    Mahmoudi, Razzaqh; Tajik, Hossein; Ehsani, Ali; Zare, Payman

    2012-01-01

    Increasing incidence of food-borne disease along with its social and economic consequences have led to conducting extensive research in order to produce safer food and develop new antimicrobial agents; among them, extensive use of probiotics and bacteriocins as biological additives is of significant importance. The aim of the present study was to evaluate the interactions (growth behavior and survival) of Listeria monocytogenes and Lactobacillus acidophilus in various stages of production, ripening and storage of Iranian white cheese. Changes in pH values at different stages of cheese ripening, along with changes in organoleptic properties of cheese were also assessed. Compared to other treatments, in the treatment of cheese with probiotic agent without starter, the most significant decrease in Listeria monocytogenes count at the end of ripening stage was observed (3.16 Log per gram cheese compared with the control group) (p < 0.05). Survival of probiotic bacteria in control samples of cheese were significantly higher when compared to cheese sample contaminated with Listeria (p < 0.05). White probiotic cheese with starter had the highest of sensory acceptability (p < 0.05). Listeria Monocytogenes count decreased during ripening period of probiotic white cheese but the bacteria survived in probiotic white cheese. Lactobacillus acidophilus count decreased during ripening period of white cheese but it did not lower to less than 106 CFU per g at the end of ripening and storage periods. PMID:25610568

  11. Supplementation of Lactobacillus acidophilus fermentation product can attenuate the acute phase response following a lipopolysaccharide challenge in pigs.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was designed to determine if feeding a Lactobacillus acidophilus fermentation product to weaned pigs would reduce stress and acute phase responses (APR) following a lipopolysaccharide (LPS) challenge. Pigs (n=30; 6.4±0.1 kilograms body weight) were housed individually in pens with ad libi...

  12. Cost effectiveness of cryoprotective agents and modified De-man Rogosa Sharpe medium on growth of Lactobacillus acidophilus.

    PubMed

    Pyar, Hassan; Peh, Kok-Khiang

    2014-04-01

    The effect of cryoprotective agents (namely, sodium chloride, sucrose, dextran, sorbitol, monosodium glutamate, glycerol, skim milk and skim milk with malt extract) and modified De-Man Rogosa Sharpe (MRS) medium, on the viability and stability of L. acidophilus ATCC 4962, was investigated. The modified MRS medium was not only economical, but it gave a relatively higher yield of L. acidophilus ATCC 4962 than the commercial MRS. Monosodium glutamate, skim milk and skim milk with malt extract provided significantly higher viable counts, with optimum concentration at 0.3%. Nevertheless, at concentration above 0.5%, there was a reduction in cell viability, which could be attributed to cell shrinkage associated with osmotic pressure changes inside the cells. It was also found that L. acidophilus ATCC 4962 was stable at 28 degrees C for eight weeks. Skim milk demonstrated a significant growth of probiotics. Skim milk was the preferred cryoprotective agent, as it is of low cost, easily available and demonstrated a significant growth of probiotics. In conclusion, modified MRS medium with skim milk is suggested for the remarkable growth and yield of L. acidophilus. PMID:25911832

  13. Growth and metabolism of selected strains of probiotic bacteria in milk.

    PubMed

    Østlie, Hilde M; Helland, Merete H; Narvhus, Judith A

    2003-10-15

    Growth and metabolism of five probiotic strains with well-documented health effects were studied in ultra-high temperature (UHT) treated milk, supplemented with 0.5% (w/v) tryptone or 0.75% (w/v) fructose. The probiotic strains were Lactobacillus acidophilus La5, Lb. acidophilus 1748, Lactobacillus rhamnosus GG, Lactobacillus reuteri SD 2112 and Bifidobacterium animalis BB12. Fermentation was followed for 72 h at 37 degrees C and the samples were analysed for pH, log cfu ml(-1), volatile compounds, organic acids and carbon dioxide. The strains reduced pH from 6.7 to between 3.9 and 4.4 after 24 h of incubation. All strains attained viable cell counts above 8.7-9.18 log cfu ml(-1) after 6-16 h of incubation. The two Lb. acidophilus strains showed a stable level of viable cells during 12-72 h of incubation but the three other strains showed a reduction of 0.4-1.1 log cfu ml(-1) from 24 to 72 h of incubation. However, all strains showed cell levels between 7.8 and 8.7 log cfu ml(-1) after 72 h of incubation. After 48 h of incubation, the amount of lactic acid produced varied according to strain from 6949 to 14,000 mg kg(-1) and acetic acid produced varied from 0 to 6901 mg kg(-1). Three of the strains metabolised citrate but only low amounts of diacetyl and acetoin were detected within strains, 0.2-0.8 and 6.5-10 mg kg(-1), respectively. Carbon dioxide produced varied from 221 to 3942 mg kg(-1) and was connected to the citrate-fermenting ability of the strain used and their carbohydrate fermentation pathway. Three of the strains produced detectable levels of acetaldehyde and the concentration varied from 9.4 to 12.6 mg kg(-1) after 24 h of incubation. All five probiotic strains showed very different profiles of metabolites during fermentation; however, the two Lb. acidophilus strains were the most alike. Our findings show the importance of controlling the fermentation time since the probiotic strains produced different amounts of metabolic products according to

  14. In vitro gastrointestinal resistance of Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 in soy and/or milk-based synbiotic apple ice creams.

    PubMed

    Matias, Natalia Silva; Padilha, Marina; Bedani, Raquel; Saad, Susana Marta Isay

    2016-10-01

    The viability and resistance to simulated gastrointestinal (GI) conditions of Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 in synbiotic ice creams, in which milk was replaced by soy extract and/or whey protein isolate (WPI) with inulin, were investigated. The ice creams were showed to be satisfactory vehicles for La-5 and Bb-12 (populations around 7.5logCFU/g), even after the whole storage period (84days/-18°C). In all formulations, the propidium monoazide qPCR (PMA-qPCR) analysis demonstrated that probiotics could resist the in vitro GI assay, with significant survival levels, achieving survival rates exceeding 50%. Additionally, scanning electron microscopy images evidenced cells with morphological differences, suggesting physiological changes in response to the induced stress during the in vitro assay. Although all formulations provided resistance to the probiotic strains under GI stress, the variation found in probiotic survival suggests that GI tolerance is indeed affected by the choice of the food matrix. PMID:27387254

  15. Two-dimensional gel-based alkaline proteome of the probiotic bacterium Lactobacillus acidophilus NCFM.

    PubMed

    Majumder, Avishek; Cai, Liyang; Ejby, Morten; Schmidt, Bjarne G; Lahtinen, Sampo J; Jacobsen, Susanne; Svensson, Birte

    2012-04-01

    Lactobacillus acidophilus NCFM (NCFM) is a well-documented probiotic bacterium isolated from human gut. Detailed 2D gel-based NCFM proteomics addressed the so-called alkaline range, i.e., pH 6-11. Proteins were identified in 150 of the 202 spots picked from the Coomassie Brilliant Blue stained 2D gel using MALDI-TOF-MS. The 102 unique gene products among the 150 protein identifications were assigned to different functional categories, and evaluated by considering a calculated distribution of abundance as well as grand average of hydrophobicity values. None of the very few available lactic acid bacteria proteome reference maps included the range of pI >7.0. The present report of such data on the proteome of NCFM fundamentally complements current knowledge on protein profiles limited to the acid and neutral pH range. PMID:22522807

  16. Synergistic effects of the Lactobacillus acidophilus surface layer and nisin on bacterial growth.

    PubMed

    Prado-Acosta, Mariano; Ruzal, Sandra M; Allievi, Mariana C; Palomino, María Mercedes; Sanchez Rivas, Carmen

    2010-02-01

    We have previously described a murein hydrolase activity for the surface layer (S-layer) of Lactobacillus acidophilus ATCC 4356. Here we show that, in combination with nisin, this S-layer acts synergistically to inhibit the growth of pathogenic Gram-negative Salmonella enterica and potential pathogenic Gram-positive bacteria, Staphylococcus aureus and Bacillus cereus. In addition, bacteriolytic effects were observed for the Gram-positive species tested. We postulate that the S-layer enhances the access of nisin into the cell membrane by enabling it to cross the cell wall, while nisin provides the sudden ion-nonspecific dissipation of the proton motive force required to enhance the S-layer murein hydrolase activity. PMID:19948852

  17. Optimization of Lactobacillus acidophilus cultivation using taro waste and evaluation of its biological activity.

    PubMed

    Hsieh, Shu-Chen; Liu, Jui-Ming; Pua, Xiao-Hui; Ting, Yuwen; Hsu, Ren-Jun; Cheng, Kuan-Chen

    2016-03-01

    In this study, taro waste (TW) was utilized for Lactobacillus acidophilus BCRC 14079 cultivation and the anti-tumor and immune-modulatory properties of heat-killed cells (HKCs), cytoplasmic fraction (CF), and exopolysaccharide (EPS) were evaluated. The optimum liquefaction enzyme dosage, temperature, and time determined by Box-Behnken design response surface methodology (BBD-RSM) were 9 mL/L of α-amylase, 79.2 °C, and 5 h of reaction, respectively. The optimum temperature and reaction time for saccharification were determined as 60 °C and 3 h. The optimum medium, CGMY1 medium, constitutes of TW hydrolysate containing 37 g/L of glucose, 25 g/L of corn gluten meal (CGM), and 1 g/L of yeast extract (YE). Results of MTT assay showed that HKCs and EPS from CGM medium exhibited the highest anti-proliferative in HT-29 (IC50 of HKCs, 467.25 μg/mL; EPS, 716.10 μg/mL) and in Caco-2 cells (IC50 of EPS, 741.60 μg/mL). Luciferase-based NF-ΚB and COX-2 systems indicated HKCs from CGM medium stimulated the highest expression of luciferin in both systems. The luciferase activities by using 100 and 500 μg/mL of HKCs from CGM were 24.30- and 45.83-fold in NF-ΚB system and 11.54- and 4.93-fold in COX-2 system higher than the control. In conclusion, this study demonstrated the potential of TW medium for L. acidophilus cultivation and the production of non-viable probiotics with enhanced biological activities. PMID:26572522

  18. Effect of Porphyromonas gingivalis and Lactobacillus acidophilus on secretion of IL1B, IL6, and IL8 by gingival epithelial cells.

    PubMed

    Zhao, Jun-jun; Feng, Xi-ping; Zhang, Xiu-li; Le, Ke-yi

    2012-08-01

    Porphyromonas gingivalis alters cytokine expression in gingival epithelial cells, stimulating inflammatory responses that may lead to periodontal disease. This study explored the effect of Lactobacillus acidophilus on the specific expressions of the interleukins (ILs) IL1B, IL6, and IL8 induced by the pathogen. Human gingival epithelial cells were co-cultured with P. gingivalis, L. acidophilus, or L. acidophilus + P. gingivalis; the control group consisted of the cells alone. Protein and gene expression levels of the ILs were detected using ELISA and qRT-PCR, respectively. The supernatant from the P. gingivalis group held significantly higher protein and mRNA levels of IL1B, IL6, and IL8, compared to the control group. In the mixed bacterial group (L. acidophilus + P. gingivalis), the levels of all three ILs decreased with increasing concentrations of L. acidophilus and were significantly different from the P. gingivalis group. This suggests that in gingival cells, L. acidophilus offsets the P. gingivalis-induced secretion of these ILs in a dose-dependent manner. PMID:22382516

  19. Systemic augmentation of the immune response in mice by feeding fermented milks with Lactobacillus casei and Lactobacillus acidophilus.

    PubMed Central

    Perdigón, G; de Macias, M E; Alvarez, S; Oliver, G; de Ruiz Holgado, A P

    1988-01-01

    This study investigates the effect of feeding fermented milks with Lactobacillus casei, Lactobacillus acidophilus and a mixture of both micro-organisms on the specific and non-specific host defence mechanisms in Swiss mice. Animals fed with fermented milk for 8 days (100 micrograms/day) showed an increase in both phagocytic and lymphocytic activity. This activation of the immune system began on the 3rd day, reached a maximum on the 5th, and decreased slightly on the 8th day of feeding. In the 8-day treated mice, boosted with a single dose (100 micrograms) on the 11th day, the immune response increased further. The feeding with fermented milk produced neither hepatomegaly nor splenomegaly. These results suggest that L. casei and L. acidophilus, associated with intestinal mucosae, can influence the level of activation of the immune system. The possible clinical application of fermented milks as immunopotentiators is also discussed. PMID:3123370

  20. Effects of synbiotic fermented milk containing Lactobacillus acidophilus La-5 and Bifidobacterium animalis ssp. lactis BB-12 on the fecal microbiota of adults with irritable bowel syndrome: A randomized double-blind, placebo-controlled trial.

    PubMed

    Bogovič Matijašić, Bojana; Obermajer, Tanja; Lipoglavšek, Luka; Sernel, Tjaša; Locatelli, Igor; Kos, Mitja; Šmid, Alenka; Rogelj, Irena

    2016-07-01

    We conducted a randomized double-blind, placebo-controlled multicentric study to investigate the influence of a synbiotic fermented milk on the fecal microbiota composition of 30 adults with irritable bowel syndrome (IBS). The synbiotic product contained Lactobacillus acidophilus La-5, Bifidobacterium animalis ssp. lactis BB-12, Streptococcus thermophilus, and dietary fiber (90% inulin, 10% oligofructose), and a heat-treated fermented milk without probiotic bacteria or dietary fiber served as placebo. Stool samples were collected after a run-in period, a 4-wk consumption period, and a 1-wk follow-up period, and were subjected to real-time PCR and 16S rDNA profiling by next-generation sequencing. After 4wk of synbiotic (11 subjects) or placebo (19 subjects) consumption, a greater increase in DNA specific for L. acidophilus La-5 and Bifidobacterium animalis ssp. lactis was detected in the feces of the synbiotic group compared with the placebo group by quantitative real-time PCR. After 1wk of follow-up, the content of L. acidophilus La-5 and B. animalis ssp. lactis decreased to levels close to initial levels. No significant changes with time or differences between the groups were observed for Lactobacillus, Enterobacteriaceae, Bifidobacterium, or all bacteria. The presence of viable BB-12- and La-5-like bacteria in the feces resulting from the intake of synbiotic product was confirmed by random amplification of polymorphic DNA (RAPD)-PCR. At the end of consumption period, the feces of all subjects assigned to the synbiotic group contained viable bacteria with a BB-12-like RAPD profile, and after 1wk of follow-up, BB-12-like bacteria remained in the feces of 87.5% of these subjects. The presence of La-5-like colonies was observed less frequently (37.5 and 25% of subjects, respectively). Next-generation sequencing of 16S rDNA amplicons revealed that only the percentage of sequences assigned to Strep. thermophilus was temporarily increased in both groups, whereas the

  1. Transcriptional and Functional Analysis of Oxalyl-Coenzyme A (CoA) Decarboxylase and Formyl-CoA Transferase Genes from Lactobacillus acidophilus

    PubMed Central

    Azcarate-Peril, M. Andrea; Bruno-Bárcena, Jose M.; Hassan, Hosni M.; Klaenhammer, Todd R.

    2006-01-01

    Oxalic acid is found in dietary sources (such as coffee, tea, and chocolate) or is produced by the intestinal microflora from metabolic precursors, like ascorbic acid. In the human intestine, oxalate may combine with calcium, sodium, magnesium, or potassium to form less soluble salts, which can cause pathological disorders such as hyperoxaluria, urolithiasis, and renal failure in humans. In this study, an operon containing genes homologous to a formyl coenzyme A transferase gene (frc) and an oxalyl coenzyme A decarboxylase gene (oxc) was identified in the genome of the probiotic bacterium Lactobacillus acidophilus. Physiological analysis of a mutant harboring a deleted version of the frc gene confirmed that frc expression specifically improves survival in the presence of oxalic acid at pH 3.5 compared with the survival of the wild-type strain. Moreover, the frc mutant was unable to degrade oxalate. These genes, which have not previously been described in lactobacilli, appear to be responsible for oxalate degradation in this organism. Transcriptional analysis using cDNA microarrays and reverse transcription-quantitative PCR revealed that mildly acidic conditions were a prerequisite for frc and oxc transcription. As a consequence, oxalate-dependent induction of these genes occurred only in cells first adapted to subinhibitory concentrations of oxalate and then exposed to pH 5.5. Where genome information was available, other lactic acid bacteria were screened for frc and oxc genes. With the exception of Lactobacillus gasseri and Bifidobacterium lactis, none of the other strains harbored genes for oxalate utilization. PMID:16517636

  2. Plant extract enhances the viability of Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus acidophilus in probiotic nonfat yogurt.

    PubMed

    Michael, Minto; Phebus, Randall K; Schmidt, Karen A

    2015-01-01

    A commercial plant extract (prepared from olive, garlic, onion and citrus extracts with sodium acetate (SA) as a carrier) was evaluated to extend the viability of yogurt starter and probiotic bacteria as a means to enhance the shelf life of live and active culture, probiotic nonfat yogurt. Yogurts prepared from three different formulas (0.5* plant extract, 0.25* SA, or no supplement) and cultures (yogurt starter plus Bifidobacterium animalis,Lactobacillus acidophilus, or both probiotics) were assessed weekly during 29 days of storage at 5°C. Supplemented yogurt mixes had greater buffering capacities than non-supplemented yogurt mixes. At the end of storage, Lactobacillus bulgaricus and L. acidophilus counts in supplemented yogurts were greater compared with non-supplemented yogurts. Supplementation did not affect Streptococcus thermophilus and B. animalis counts. Hence the greater buffering capacity of yogurt containing plant extract could enhance the longevity of the probiotics, L. bulgaricus and L. acidophilus, during storage. PMID:25650127

  3. Plant extract enhances the viability of Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus acidophilus in probiotic nonfat yogurt

    PubMed Central

    Michael, Minto; Phebus, Randall K; Schmidt, Karen A

    2015-01-01

    A commercial plant extract (prepared from olive, garlic, onion and citrus extracts with sodium acetate (SA) as a carrier) was evaluated to extend the viability of yogurt starter and probiotic bacteria as a means to enhance the shelf life of live and active culture, probiotic nonfat yogurt. Yogurts prepared from three different formulas (0.5* plant extract, 0.25* SA, or no supplement) and cultures (yogurt starter plus Bifidobacterium animalis,Lactobacillus acidophilus, or both probiotics) were assessed weekly during 29 days of storage at 5°C. Supplemented yogurt mixes had greater buffering capacities than non-supplemented yogurt mixes. At the end of storage, Lactobacillus bulgaricus and L. acidophilus counts in supplemented yogurts were greater compared with non-supplemented yogurts. Supplementation did not affect Streptococcus thermophilus and B. animalis counts. Hence the greater buffering capacity of yogurt containing plant extract could enhance the longevity of the probiotics, L. bulgaricus and L. acidophilus, during storage. PMID:25650127

  4. Influence of a combination of Lactobacillus acidophilus NCFM and lactitol on healthy elderly: intestinal and immune parameters.

    PubMed

    Ouwehand, Arthur C; Tiihonen, Kirsti; Saarinen, Markku; Putaala, Heli; Rautonen, Nina

    2009-02-01

    With increasing age, a number of physiological changes take place which are reflected in immune and bowel function. These changes may relate to the commonly assumed age-related changes in intestinal microbiota; most noticeably a reduction in bifidobacteria. The current study aimed at modifying the intestinal microbiota with a potential synbiotic on selected immune and microbiota markers. Healthy elderly subjects were randomised to consume during 2 weeks either a placebo (sucrose) or a combination of lactitol and Lactobacillus acidophilus NCFM twice daily in a double-blind parallel trial. After the intervention, stool frequency was higher in the synbiotic group than in the placebo group and a significant increase in faecal L. acidophilus NCFM levels was observed in the synbiotic group, after baseline correction. In contrast to the generally held opinion, the study subjects had faecal Bifidobacterium levels that were similar to those reported in healthy young adults. These levels were, nevertheless, significantly increased by the intervention. Levels of SCFA were not changed significantly. Of the measured immune markers, PGE2 levels were different between treatments and IgA levels changed over time. These changes were modest which may relate to the fact that the volunteers were healthy. Spermidine levels changed over time which may suggest an improved mucosal integrity and intestinal motility. The results suggest that consumption of lactitol combined with L. acidophilus NCFM twice daily may improve some markers of the intestinal microbiota composition and mucosal functions. PMID:18634707

  5. Viability of Lactobacillus acidophilus in synbiotic guava mousses and its survival under in vitro simulated gastrointestinal conditions.

    PubMed

    Buriti, Flávia C A; Castro, Inar A; Saad, Susana M I

    2010-02-28

    The effects of refrigeration, freezing and substitution of milk fat by inulin and whey protein concentrate (WPC) on Lactobacillus acidophilus La-5 viability and resistance to gastric and enteric simulated conditions in synbiotic guava mousses effects were investigated. Refrigerated mousses supplemented with WPC presented the best probiotic viability, ranging from 7.77 to 6.24 log cfu/g during 28 days of storage. The highest probiotic populations, above 7.45 log cfu/g, were observed for all frozen mousses during 112 days of storage. Decreased L. acidophilus survival during the in vitro gastrointestinal simulation was observed both for refrigerated and frozen mousses. Nonetheless, for the refrigerated mousses, the addition of inulin enhanced the probiotic survival during the in vitro assays in the first week of storage. L. acidophilus survival in simulated gastrointestinal fluids was also improved through freezing. The frozen storage may be used to provide increased shelf-life for synbiotic guava mousses. Even though the protective effect of inulin and WPC on the probiotic microorganism tested was shown to be more specific for the refrigerated products, the partial replacement of milk fat by these ingredients may also help, as it improves the nutritional value of mousses in both storage conditions. PMID:20056289

  6. Preparation and Characterization of Alginate and Psyllium Beads Containing Lactobacillus acidophilus

    PubMed Central

    Lotfipour, Farzaneh; Mirzaeei, Shahla; Maghsoodi, Maryam

    2012-01-01

    This paper describes preparation and characterization of beads of alginate and psyllium containing probiotic bacteria of Lactobacillus acidophilus DMSZ20079. Twelve different formulations containing alginate (ALG) and alginate-psyllium (ALG-PSL) were prepared using extrusion technique. The prepared beads were characterized in terms of size, morphology and surface properties, encapsulation efficiency, viabilities in acid (pH 1.8, 2 hours) and bile (0.5% w/v, 2 hours) conditions, and release in simulated colon pH conditions. The results showed that spherical beads with narrow size distribution ranging from 1.59 ± 0.04 to 1.67 ± 0.09 mm for ALG and from 1.61 ± 0.06 to 1.80 ± 0.07 mm for ALG-PSL with encapsulation efficiency higher than 98% were achieved. Furthermore, addition of PSL into ALG enhanced the integrity of prepared beads in comparison with ALG formulations. The results indicated that incorporation of PSL into alginate beads improved viability of the bacteria in acidic conditions as well as bile conditions. Also, stimulating effect of PSL on the probiotic bacteria was observed through 20-hour incubation in simulated colonic pH solution. According to our in vitro studies, PSL can be a suitable polymer candidate for partial substitution with ALG for probiotic coating. PMID:22649306

  7. Optimization of anticancer exopolysaccharide production from probiotic Lactobacillus acidophilus by response surface methodology.

    PubMed

    Deepak, Venkataraman; Ram Kumar Pandian, Sureshbabu; Sivasubramaniam, Shiva D; Nellaiah, Hariharan; Sundar, Krishnan

    2016-04-01

    Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths in the Western world. Recently, much attention has been focused on decreasing the risk of CRC by consuming probiotics. In the present study, exopolysaccharide (EPS) extracted from Lactobacillus acidophilus was found to inhibit the growth of CaCo2 colon cancer cell line in a dose-dependent manner. The experiment was performed in both normoxic and hypoxic conditions, and EPS was found to reduce the survival of CaCo2 cell line in both the conditions. Quantitative polymerase chain reaction (qPCR) studies demonstrated that EPS treatment upregulated the expression of peroxisome proliferator activator receptor-γ (PPAR-γ) in both normoxia and hypoxia conditions, whereas it upregulated the expression of erythropoietin (EPO) in the normoxic condition, but there was no significant expression under hypoxic conditions. Hence, the EPS production was optimized by Plackett-Burman design followed by central composite rotatory design. The optimized production of EPS at 24 hr was found to be 400 mg/L. During batch cultivation the production peaked at 21 hr, resulting in an EPS concentration of 597 mg/L. PMID:25831127

  8. In vitro evaluation of anticancer properties of exopolysaccharides from Lactobacillus acidophilus in colon cancer cell lines.

    PubMed

    Deepak, Venkataraman; Ramachandran, Sharavan; Balahmar, Reham Mohammed; Pandian, Sureshbabu Ram Kumar; Sivasubramaniam, Shiva D; Nellaiah, Hariharan; Sundar, Krishnan

    2016-02-01

    The present work aims at studying the effect of exopolysaccharides (EPS) from Lactobacillus acidophilus on the colon cancer cell lines in vitro. Initial analysis showed that EPS has antioxidative properties. EPS was also found to induce cytotoxicity in two colon cancer cell lines, viz. HCT15 and CaCo2 under normoxia and hypoxia. The membrane integrity was also found to be affected in EPS-treated cells. Once the toxic concentration was determined (5 mg/ml), the effect of EPS on the messenger RNA (mRNA) expression of various genes was studied by quantitative real-time (RT)-PCR under both normoxic and hypoxic conditions. The results suggest that EPS downregulated the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α (HIF-1α) and upregulated the expression of tissue inhibitor of metalloproteinases-3 (TIMP-3), hypoxia-inducible factor-2α (HIF-2α), and hemeoxygenase-1 (HO-1). An increase in plasminogen activator inhibitor-1 (PAI-1) was also observed. These results show that EPS may inhibit the expressions of genes involved in tumor angiogenesis and survival. Increase in the expression of HO-1 also shows that EPS have antioxidative properties. PMID:26659393

  9. Cloning, expression and characterization of a mucin-binding GAPDH from Lactobacillus acidophilus.

    PubMed

    Patel, Dhaval K; Shah, Kunal R; Pappachan, Anju; Gupta, Sarita; Singh, Desh Deepak

    2016-10-01

    Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a ubiquitous enzyme involved in glycolysis. It is also referred to as a moonlighting protein as it has many diverse functions like regulation of apoptosis, iron homeostasis, cell-matrix interactions, adherence to human colon etc. apart from its principal role in glycolysis. Lactobacilli are lactic acid bacteria which colonize the human gut and confer various health benefits to humans. In the present study, we have cloned, expressed and purified the GAPDH from Lactobacillus acidophilus to get a recombinant product (r-LaGAPDH) and characterized it. Size exclusion chromatography shows that r-LaGAPDH exists as a tetramer in solution and have a mucin binding and hemagglutination activity indicating carbohydrate like binding adhesion mechanism. Fluorescence spectroscopy studies showed an interaction of r-LaGAPDH with mannose, galactose, N-acetylgalactosamine and N-acetylglucosamine with a Kd of 3.6±0.7×10(-3)M, 4.34±0.09×10(-3)M, 4±0.87×10(-3)M and 3.7±0.28×10(-3)M respectively. We hope that this preliminary data will generate more interest in further elucidation of the roles of GAPDH in the adhesion processes of the bacteria. PMID:27180300

  10. Effect of probiotics Lactobacillus acidophilus on Citrobacter rodentium colitis: the role of dendritic cells.

    PubMed

    Chen, Chien-Chang; Chiu, Cheng-Hsun; Lin, Tzou-Yien; Shi, Hai Ning; Walker, W Allan

    2009-02-01

    Modulation of the intestinal immune response early in life by administration of probiotic bacteria may be an effective strategy for preventing or attenuating infectious diarrhea. We preinoculated the mice early in life with the probiotic bacteria Lactobacillus acidophilus NCFM (La) at age 2 wk. Dendritic cells (DCs) were collected and purified from mesenteric lymph nodes (MLN) and spleens of the BalbC/ByJ mice. DC isolation and adoptive transfer was used to examine the function of probiotics. We demonstrated that when mice were adoptively transferred with La-primed DCs (t-LaDC) instead of oral consumption with La, there was a similar effect on fecal bacteria counts, IgA levels, and colonic histopathology, as well as cytokine levels in MLN when there was intestinal bacterial infection. The above findings suggest that DCs play a key role in probiotics attenuating Citrobacter rodentium (Cr) colitis. Moreover, the location of La-primed DC hints that there is interaction of DCs and T cells in the digestive system of the host. Up-regulated expression of a surface marker on DCs indicated that inoculation with probiotics will stimulate the function of DCs, thereby further increasing immune response triggered by DC. PMID:19262293

  11. Synbiotic yogurt-ice cream produced via incorporation of microencapsulated lactobacillus acidophilus (la-5) and fructooligosaccharide.

    PubMed

    Ahmadi, Abbas; Milani, Elnaz; Madadlou, Ashkan; Mortazavi, Seyed Ali; Mokarram, Reza Rezaei; Salarbashi, Davoud

    2014-08-01

    Yogurt-ice cream is a nutritious product with a refreshing taste and durability profoundly longer than that of yogurt. The probiotic Lactobacillus acidophilus (La-5) cells either in free or encapsulated form were incorporated into yog-ice cream and their survivability were studied. Fructooligosaccharide (FOS) as a prebiotic compound at three levels (0, 4 & 8 % w/w) was added to yogurt-ice cream mix and its effects on some chemical properties, overrun and firmness of product were evaluated. The higher the incorporated FOS concentration, the lower were the pH value and higher the total solid content of treatments. FOS incorporation (8 %) significantly increased the overrun of treatments and reduced their firmness. The viable counts of free probiotics decreased from ~9.55 to ~7.3 log cfu/g after 60 days of frozen storage while that of encapsulated cells merely decreased less than 1 log cycle. Encapsulation with alginate microbeads protected the probiotic cells against injuries in the freezing stage as well as, during frozen storage. PMID:25114349

  12. Elaboration of a probiotic oblea from whey fermented using Lactobacillus acidophilus or Bifidobacterium infantis.

    PubMed

    Trujillo-de Santiago, G; Sáenz-Collins, C P; Rojas-de Gante, C

    2012-12-01

    A novel probiotic product was developed, which was formulated as an oblea (wafer-type dehydrated traditional Mexican dessert) using goat sweet whey fermented with Bifidobacterium infantis or Lactobacillus acidophilus. To obtain the probiotic oblea, the fermented whey was formulated with prebiotic carbohydrates (inulin and resistant starch) and gelatin, and the preparation was poured onto a polytetrafluoroethylene-coated nonstick baking pan, dried in a convection oven, and finally dehydrated at a low relative humidity and room temperature (23±2°C). The amounts of prebiotic carbohydrates and gelatin to be used in the formulation were determined by a factorial experimental design. An untrained sensory panel evaluated 3 quality characteristics (film formation, homogeneity, and smoothness) in the final product. Three different drying temperatures were tested, namely, 40, 55, and 70°C. Bacterial survival at each temperature was determined by viable plate-counting. The best formulation, based on the quality characteristics tested, consisted of 58.33% (vol/vol) of fermented whey, 8.33% (vol/vol) of 6% (wt/vol) resistant starch dispersion, 16.66% (vol/vol) of 15% (wt/vol) inulin solution, and 16.66% (vol/vol) of a 10% (wt/vol) gelatin solution. Drying at 55±2°C for 2.66±0.22 h allowed for concentrations of probiotic bacteria above 9 log(10) cfu/g, which is above the minimum concentration required in a probiotic product. PMID:23040019

  13. Impact of Bifidobacterium animalis subsp. lactis BB-12 and, Lactobacillus acidophilus LA-5-containing yoghurt, on fecal bacterial counts of healthy adults.

    PubMed

    Savard, Patricia; Lamarche, Benoît; Paradis, Marie-Eve; Thiboutot, Hélène; Laurin, Émilie; Roy, Denis

    2011-09-01

    This randomized, placebo-controlled, double blind, parallel dose-response study investigated the impact of 4-week commercial yoghurt consumption supplemented with Bifidobacterium animalis subsp. lactis (BB-12) and Lactobacillus acidophilus (LA-5) on fecal bacterial counts of healthy adults. Fifty-eight volunteers were randomly assigned to three different groups: 1. placebo (no probiotic, no starter and no green tea extract); 2. Yoptimal (10(9)cfu/100g of BB-12 and LA-5 and 40mg of green tea extract) and 3. Yoptimal-10 (10(10)cfu/100g of BB-12, 10(9)cfu/100g of LA-5 and 40mg of green tea extract). These yoghurt products also contained Lactobacillus delbrueckii subsp. bulgaricus (10(7)cfu/100g) and Streptococcus thermophilus (10(10)cfu/100g). The quantitative PCR (qPCR) results showed that there were significant increases (P=0.02) in bifidobacteria counts with the Yoptimal treatment as compared to baseline. The fecal numbers of B. animalis subsp. lactis and LA-5 significantly increased in the two probiotic treatments compared to the placebo treatment. Viable counts of fecal lactobacilli were significantly higher (P=0.05) and those of enterococci were significantly lower (P=0.04) after the intervention when compared to placebo. No significant difference was observed between treatments in volunteers' weight, waist girth, blood pressure, fasting plasma triglyceride and HDL-C concentrations, as well as cholesterol/HDL-cholesterol ratio. However, a significant increase in plasma cholesterol levels was observed in the placebo group (P=0.0018) but the levels remained stable in the two probiotic yoghurt groups. These results show that probiotic strains supplemented in the form of yoghurt remain active during gut transit and are associated with an increase in beneficial bacteria and a reduction in potentially pathogenic bacteria. This trial was registered at clinicaltrials.gov as NCT00730626. PMID:21296446

  14. Anaerobic induction of adherence to laminin in Lactobacillus gasseri strains by contact with solid surface.

    PubMed

    Horie, Masanori; Murakami, Takatomo; Sato, Takumi; Tarusawa, Yukiko; Nakamura, Shingo; Toba, Takahiro

    2005-10-01

    The effect of growth conditions on adhesion was studied in six species belonging to Lactobacillus acidophilus homology groups. Namely, 17 strains including 6 fresh isolates of L. gasseri from human feces were assessed for their adherence to immobilized fibronectin, laminin, and type IV collagen. These extracellular matrix proteins were used as a model of damaged intestinal mucosa. When the bacteria were grown on MRS agar under anaerobic conditions, all eight L. gasseri strains and one L. johnsonii strain showed strong adhesiveness to laminin, but not when grown in static MRS broth. A similar pattern was observed in four L. gasseri strains in terms of adherence to fibronectin. No L. gasseri or L. johnsonii strains exhibited adhesion to type IV collagen under either growth condition. Adhesion of L. acidophilus, L. crispatus, L. amylovorus, and L. gallinarum was not affected by the growth conditions. Although protease treatment of L. gasseri cells abolished the adhesion, periodate oxidation of the cells increased it except in one strain. The adherence of L. gasseri cells was diminished by periodate and alpha-mannosidase treatments of immobilized laminin. The above results suggest that mannose-specific proteinaceous adhesion can be induced in L. gasseri by contact with a mucosal surface in the anaerobic intestinal lumen. PMID:16086101

  15. The Effects of Lactobacillus acidophilus on the Intestinal Smooth Muscle Contraction through PKC/MLCK/MLC Signaling Pathway in TBI Mouse Model

    PubMed Central

    Fang, Huan; Zhu, Lina; Gao, Ning; Zhu, Jingci

    2015-01-01

    Clinical studies have shown that probiotics influence gastrointestinal motility. However, the molecular mechanisms by which probiotic Lactobacillus modulates intestinal motility in traumatic brain injury (TBI) mouse model have not been explored. In the present study, we provided evidence showing that treatment of TBI mice with Lactobacillus acidophilus significantly improved the terminal ileum villus morphology, restored the impaired interstitial cells of Cajal (ICC) and the disrupted ICC networks after TBI, and prevented TBI-mediated inhibition of contractile activity in intestinal smooth muscle. Mechanistically, the decreased concentration of MLCK, phospho-MLC20 and phospho-MYPT1 and increased concentration of MLCP and PKC were observed after TBI, and these events mediated by TBI were efficiently prevented by Lactobacillus acidophilus application. These findings may provide a novel mechanistic basis for the application of Lactobacillus acidophilus in the treatment of TBI. PMID:26030918

  16. The effects of Lactobacillus acidophilus as feed supplement on skin mucosal immune parameters, intestinal microbiota, stress resistance and growth performance of black swordtail (Xiphophorus helleri).

    PubMed

    Hoseinifar, Seyed Hossein; Roosta, Zahra; Hajimoradloo, Abdolmajid; Vakili, Farzaneh

    2015-02-01

    The present study evaluates the effects of different levels of dietary Lactobacillus acidophilus as feed supplement on intestinal microbiota, skin mucus immune parameters and salinity stress resistance as well as growth performance of black swordtail (Xiphophorus helleri). One-thousand and eight hundred healthy black swordtail larvae (0.03 ± 0.001 g) were randomly distributed in 12 tanks (100 L) at a density of 150 fish per aquaria and fed different levels of dietary L. acidophilus (0, 1.5 × 10(8), 3 × 10(8) and 6 × 10(8) CFU g(-1)) for 10 weeks. At the end of trial, there were significant differences among antibacterial activity of skin mucus in probiotic fed fish and control group (P < 0.05). Furthermore, the skin mucus protein level and alkaline phosphatase activity in control group were significantly lower than those of L. acidophilus fed fish (P < 0.05). Microbiological assessments revealed that feeding with probiotic supplemented diet remarkably increased total autochthonous bacteria and autochthonous lactic acid bacteria levels (P < 0.05). The results showed that dietary administration of L. acidophilus significantly elevated black swordtail resistance against salinity stress (i.e survival %) (P < 0.05). Also, dietary administration of different levels of L. acidophilus improved weight gain, SGR, FCR compared to fish fed unsupplemented diet (P < 0.05). These results demonstrate beneficial effects of dietary L. acidophilus on mucosal immune parameters, intestinal microbiota, stress resistance and growth parameters of black swordtail and the appropriate inclusion is 6 × 10(8) CFU g(-1). PMID:25514375

  17. Effect of aqueous and alcoholic Stevia (Stevia rebaudiana) extracts against Streptococcus mutans and Lactobacillus acidophilus in comparison to chlorhexidine: An in vitro study

    PubMed Central

    Ajagannanavar, Sunil Lingaraj; Shamarao, Supreetha; Battur, Hemant; Tikare, Shreyas; Al-Kheraif, Abdulaziz Abdullah; Al Sayed, Mohammed Sayed Al Esawy

    2014-01-01

    Introduction: Stevia (S. rebaudiana) a herb which has medicinal value and was used in ancient times as a remedy for a great diversity of ailments and sweetener. Leaves of Stevia contain a high concentration of Stevioside and Rebaudioside which are supposed to be sweetening agents. Aim: To compare the efficacy of aqueous and alcoholic S. rebaudiana extract against Streptococcus mutans and Lactobacillus acidophilus in comparison to chlorhexidine. Materials and Methods: In the first part of the study, various concentrations of aqueous and ethanolic Stevia extract were prepared in the laboratory of Pharmacy College. It was then subjected to microbiological assay to determine its zone of inhibition using Agar disk diffusion test and minimum inhibitory concentration (MIC) using serial broth dilution method against Streptococcus mutans and Lactobacillus acidophilus. Chlorhexidine was used as a positive control. One way Analysis of Variance (ANOVA) test was used for multiple group comparisons followed by Tukey post hoc for group wise comparisons. Results: Minimum inhibitory concentration (MIC) of aqueous and ethnolic Stevia extract against Streptococcus mutans and Lactobacillus acidophilus were 25% and 12.5% respectively. Mean zone of inhibition of the aqueous and alcoholic Stevia extracts against Streptococcus mutans at 48 hours were 22.8 mm and 26.7 mm respectively. Mean zone of inhibition of the aqueous and alcoholic Stevia extracts against Lactobacillus acidophilus at 48 hours were 14.4 mm and 15.1 mm respectively. Mean zone of inhibition of the chlorhexidine against Streptococcus mutans and Lactobacillus acidophilus at 48 hours was 20.5 and 13.2 respectively. Conclusion: The inhibitory effect shown by alcoholic Stevia extract against Streptococcus mutans and Lactobacillus acidophilus was superior when compared with that of aqueous form and was inferior when compared with Chlorhexidine. PMID:25558451

  18. Effect of Aqueous and Alcoholic Licorice (Glycyrrhiza Glabra) Root Extract Against Streptococcus Mutans and Lactobacillus Acidophilus in Comparison to Chlorhexidine: An In Vitro Study

    PubMed Central

    Ajagannanavar, Sunil Lingaraj; Battur, Hemant; Shamarao, Supreetha; Sivakumar, Vivek; Patil, Pavan Uday; Shanavas, P

    2014-01-01

    Background: Glycyrrhiza (licorice) an herb, which has medicinal value and was used in ancient times as a remedy for a great diversity of ailments and sweetener. Roots of Glycyrrhiza contain a high concentration of saponin and glycyrrhizin, which are supposed to be sweetening agents. The aim of the study was to compare the efficacy of aqueous and alcoholic licorice root extract against Streptococcus mutans and Lactobacillus acidophilus in comparison to chlorhexidine (CHX). Materials and Methods: In the first part of the study, various concentrations of aqueous and ethanolic licorice extract were prepared in the laboratory of Pharmacy College. It was then subjected to microbiological assay to determine its zone of inhibition using agar disk diffusion test and minimum inhibitory concentration (MIC) using serial broth dilution method against S. mutans and L. acidophilus. CHX was used as a positive control. Results: MIC of aqueous and ethnolic licorice root extract against S. mutans and L. acidophilus were 25% and 12.5%, respectively. Mean zone of inhibition of the aqueous and alcoholic licorice extracts against S. mutans at 48 h were 22.8 mm and 26.7 mm, respectively. Mean zone of inhibition of the aqueous and alcoholic licorice extracts against L. acidophilus at 48 h were 14.4 mm and 15.1 mm, respectively. Mean zone of inhibition of the CHX against S. mutans and L. acidophilus at 48 h was 20.5 and 13.2, respectively. Conclusion: The inhibitory effect shown by alcoholic licorice root extract against S. mutans and L. acidophilus was superior when compared with that of aqueous form and CHX. PMID:25214729

  19. Directed chromosomal integration and expression of the reporter gene gusA3 in Lactobacillus acidophilus NCFM.

    PubMed

    Douglas, Grace L; Klaenhammer, Todd R

    2011-10-01

    Lactobacillus acidophilus NCFM is a probiotic microbe that survives passage through the human gastrointestinal tract and interacts with the host epithelium and mucosal immune cells. The potential for L. acidophilus to express antigens at mucosal surfaces has been investigated with various antigens and plasmid expression vectors. Plasmid instability and antibiotic selection complicate the possibility of testing these constructs in human clinical trials. Integrating antigen encoding genes into the chromosome for expression is expected to eliminate selection requirements and provide genetic stability. In this work, a reporter gene encoding a β-glucuronidase (GusA3) was integrated into four intergenic chromosomal locations. The integrants were tested for genetic stability and GusA3 activity. Two locations were selected for insertion downstream of constitutively highly expressed genes, one downstream of slpA (LBA0169), encoding a highly expressed surface-layer protein, and one downstream of phosphopyruvate hydratase (LBA0889), a highly expressed gene with homologs in other lactic acid bacteria. An inducible location was selected downstream of lacZ (LBA1462), encoding a β-galactosidase. A fourth location was selected in a low-expression region. The expression of gusA3 was evaluated from each location by measuring GusA3 activity on 4-methyl-umbelliferyl-β-d-glucuronide (MUG). GusA3 activity from both highly expressed loci was more than three logs higher than the gusA3-negative parent, L. acidophilus NCK1909. GusA3 activity from the lacZ locus was one log higher in cells grown in lactose than in glucose. The differences in expression levels between integration locations highlights the importance of rational targeting with gene cassettes intended for chromosomal expression. PMID:21873486

  20. Solution Structure of Acidocin B, a Circular Bacteriocin Produced by Lactobacillus acidophilus M46

    PubMed Central

    Acedo, Jeella Z.; van Belkum, Marco J.; Lohans, Christopher T.; McKay, Ryan T.; Miskolzie, Mark

    2015-01-01

    Acidocin B, a bacteriocin produced by Lactobacillus acidophilus M46, was originally reported to be a linear peptide composed of 59 amino acid residues. However, its high sequence similarity to gassericin A, a circular bacteriocin from Lactobacillus gasseri LA39, suggested that acidocin B might be circular as well. Acidocin B was purified from culture supernatant by a series of hydrophobic interaction chromatographic steps. Its circular nature was ascertained by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry and tandem mass spectrometry (MS/MS) sequencing. The peptide sequence was found to consist of 58 amino acids with a molecular mass of 5,621.5 Da. The sequence of the acidocin B biosynthetic gene cluster was also determined and showed high nucleotide sequence similarity to that of gassericin A. The nuclear magnetic resonance (NMR) solution structure of acidocin B in sodium dodecyl sulfate micelles was elucidated, revealing that it is composed of four α-helices of similar length that are folded to form a compact, globular bundle with a central pore. This is a three-dimensional structure for a member of subgroup II circular bacteriocins, which are classified based on their isoelectric points of ∼7 or lower. Comparison of acidocin B with carnocyclin A, a subgroup I circular bacteriocin with four α-helices and a pI of 10, revealed differences in the overall folding. The observed variations could be attributed to inherent diversity in their physical properties, which also required the use of different solvent systems for three-dimensional structural elucidation. PMID:25681186

  1. Efficacy of prolonged ingestion of Lactobacillus acidophilus L-92 in adult patients with atopic dermatitis.

    PubMed

    Yamamoto, Kozo; Yokoyama, Kazuhito; Matsukawa, Takehisa; Kato, Sayaka; Kato, Shinji; Yamada, Kazuhisa; Hirota, Tatsuhiko

    2016-07-01

    To evaluate the safety and efficacy of prolonged ingestion of Lactobacillus acidophilus L-92 (L-92) on skin symptoms in adult atopic dermatitis (AD) patients, a placebo-controlled double-blinded parallel-group comparison study was performed. This included daily administration of heat-killed and dried L-92 or placebo for 24wk in 50 AD patients who were 16yr old or older. The severity of skin symptoms was evaluated at baseline and at 4, 8, 12, 16, 20, and 24wk during the intervention using the investigator global assessment, eczema area and severity index, and scoring atopic dermatitis. Serum cytokine and blood marker levels were also measured at baseline and at 4, 8, 16, and 24wk during the intervention. No adverse events were reported during the study period. Compared with the placebo group, the L-92 group showed significant decreases in investigator global assessment, eczema area and severity index, and scoring atopic dermatitis. Subjective symptoms in adult AD patients were reduced by intake of L-92. Furthermore, it was suggested that sustained ingestion of L-92 resulted in suppression of scratching behavior and maintenance of remission status of skin symptoms. Sixteen weeks after the study commenced, a significant decrease in lactate dehydrogenase and a significant increase in transforming growth factor-β were observed in the L-92 group compared with the placebo group. In the L-92 group, a significant elevation of IL-12 (p70) level at the end of treatment period compared with before the treatment was observed. This study suggested that L-92 suppresses type-2-helper-T-cell-dominant inflammation by activating regulatory T cells and type 1 helper T cells. PMID:27108169

  2. Rational engineering of Lactobacillus acidophilus NCFM maltose phosphorylase into either trehalose or kojibiose dual specificity phosphorylase.

    PubMed

    Nakai, Hiroyuki; Petersen, Bent O; Westphal, Yvonne; Dilokpimol, Adiphol; Abou Hachem, Maher; Duus, Jens Ø; Schols, Henk A; Svensson, Birte

    2010-10-01

    Lactobacillus acidophilus NCFM maltose phosphorylase (LaMP) of the (alpha/alpha)(6)-barrel glycoside hydrolase family 65 (GH65) catalyses both phosphorolysis of maltose and formation of maltose by reverse phosphorolysis with beta-glucose 1-phosphate and glucose as donor and acceptor, respectively. LaMP has about 35 and 26% amino acid sequence identity with GH65 trehalose phosphorylase (TP) and kojibiose phosphorylase (KP) from Thermoanaerobacter brockii ATCC35047. The structure of L. brevis MP and multiple sequence alignment identified (alpha/alpha)(6)-barrel loop 3 that forms the rim of the active site pocket as a target for specificity engineering since it contains distinct sequences for different GH65 disaccharide phosphorylases. Substitution of LaMP His413-Glu421, His413-Ile418 and His413-Glu415 from loop 3, that include His413 and Glu415 presumably recognising the alpha-anomeric O-1 group of the glucose moiety at subsite +1, by corresponding segments from Ser426-Ala431 in TP and Thr419-Phe427 in KP, thus conferred LaMP with phosphorolytic activity towards trehalose and kojibiose, respectively. Two different loop 3 LaMP variants catalysed the formation of trehalose and kojibiose in yields superior of maltose by reverse phosphorolysis with (alpha1, alpha1)- and alpha-(1,2)-regioselectivity, respectively, as analysed by nuclear magnetic resonance. The loop 3 in GH65 disaccharide phosphorylase is thus a key determinant for specificity both in phosphorolysis and in regiospecific reverse phosphorolysis. PMID:20713411

  3. Identification and purification of a protein that induces production of the Lactobacillus acidophilus bacteriocin lactacin B.

    PubMed Central

    Barefoot, S F; Chen, Y R; Hughes, T A; Bodine, A B; Shearer, M Y; Hughes, M D

    1994-01-01

    Lactacin B is a heat-stable bacteriocin produced by Lactobacillus acidophilus N2 that is active against closely related lactobacilli, including Lactobacillus delbrueckii subsp. lactis (formerly Lactobacillus leichmannii) ATCC 4797. Pure producer cultures propagated in MRS broth (initial pH 6.5) contain no lactacin B; it is detected only in cultures maintained at pH 5.0 to 6.0 and produced optimally at pH 6.0 S. F. Barefoot and T. R. Klaenhammer, Antimicrob. Agents Chemother. 26:328-334, 1984). Associative growth of producer and indicator, L. delbrueckii subsp. lactis ATCC 4797, resulted in production of an inhibitor identical to lactacin B. Associative growth increased lactacin B production from nondetectable levels (< 100 activity units [AU]/ml) to between 3,200 and 6,400 AU/ml in MRS broth (initial pH 6.5) and resulted in early but equal production of lactacin B (approximately 25,600 AU/ml) in broth maintained at pH 6.0. Indicator cells, but not spent culture filtrates, induced lactacin B production. Indicator cells disrupted by a French pressure cell yielded cell-free filtrates containing inducing activity. Chromatofocusing and gel filtration high-performance liquid chromatography of cell-free filtrates yielded a protein with a pI of 4.1 and a molecular size of approximately 58 kDa that induced lactacin B production. Analytical isoelectric focusing yielded a single protein band. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels contained a 28-kDa protein suggesting a two-subunit structure. Protein sequencing identified an N-terminal serine and 18 additional amino acids. To our knowledge, there are not previous descriptions of proteins that induce bacteriocin production in lactic acid bacteria. Images PMID:7986029

  4. Evaluation of Lactobacillus rhamnosus GG and Lactobacillus acidophilus NCFM encapsulated using a novel impinging aerosol method in fruit food products.

    PubMed

    Sohail, Asma; Turner, Mark S; Prabawati, Elisabeth Kartika; Coombes, Allan G A; Bhandari, Bhesh

    2012-07-01

    This study investigated the effect of microencapsulation on the survival of Lactobacillus rhamnosus GG and Lactobacillus acidophilus NCFM and their acidification in orange juice at 25°C for nine days and at 4°C over thirty five days of storage. Alginate micro beads (10-40 μm) containing the probiotics were produced by a novel dual aerosol method of alginate and CaCl(2) cross linking solution. Unencapsulated L. rhamnosus GG was found to have excellent survivability in orange juice at both temperatures. However unencapsulated L. acidophilus NCFM showed significant reduction in viability. Encapsulation of these two bacteria did not significantly enhance survivability but did reduce acidification at 25°C and 4°C. In agreement with this, encapsulation of L. rhamnosus GG also reduced acidification in pear and peach fruit-based foods at 25°C, however at 4°C difference in pH was insignificant between free and encapsulated cells. In conclusion, L. rhamnosus GG showed excellent survival in orange juice and microencapsulation has potential in reducing acidification and possible negative sensory effects of probiotics in orange juice and other fruit-based products. PMID:22633536

  5. Production of Succinic Acid from Citric Acid and Related Acids by Lactobacillus Strains

    PubMed Central

    Kaneuchi, Choji; Seki, Masako; Komagata, Kazuo

    1988-01-01

    A number of Lactobacillus strains produced succinic acid in de Man-Rogosa-Sharpe broth to various extents. Among 86 fresh isolates from fermented cane molasses in Thailand, 30 strains (35%) produced succinic acid; namely, 23 of 39 Lactobacillus reuteri strains, 6 of 18 L. cellobiosus strains, and 1 of 6 unidentified strains. All of 10 L. casei subsp. casei strains, 5 L. casei subsp. rhamnosus strains, 6 L. mali strains, and 2 L. buchneri strains did not produce succinic acid. Among 58 known strains including 48 type strains of different Lactobacillus species, the strains of L. acidophilus, L. crispatus, L. jensenii, and L. parvus produced succinic acid to the same extent as the most active fresh isolates, and those of L. alimentarius, L. collinoides, L. farciminis, L. fructivorans (1 of 2 strains tested), L. malefermentans, and L. reuteri were also positive, to lesser extents. Diammonium citrate in de Man-Rogosa-Sharpe broth was determined as a precursor of the succinic acid produced. Production rates were about 70% on a molar basis with two fresh strains tested. Succinic acid was also produced from fumaric and malic acids but not from dl-isocitric, α-ketoglutaric, and pyruvic acids. The present study is considered to provide the first evidence on the production of succinic acid, an important flavoring substance in dairy products and fermented beverages, from citrate by lactobacilli. PMID:16347795

  6. Use of colony-based bacterial strain typing for tracking the fate of Lactobacillus strains during human consumption

    PubMed Central

    2009-01-01

    Background The Lactic Acid Bacteria (LAB) are important components of the healthy gut flora and have been used extensively as probiotics. Understanding the cultivable diversity of LAB before and after probiotic administration, and being able to track the fate of administered probiotic isolates during feeding are important parameters to consider in the design of clinical trials to assess probiotic efficacy. Several methods may be used to identify bacteria at the strain level, however, PCR-based methods such as Random Amplified Polymorphic DNA (RAPD) are particularly suited to rapid analysis. We examined the cultivable diversity of LAB in the human gut before and after feeding with two Lactobacillus strains, and also tracked the fate of these two administered strains using a RAPD technique. Results A RAPD typing scheme was developed to genetically type LAB isolates from a wide range of species, and optimised for direct application to bacterial colony growth. A high-throughput strategy for fingerprinting the cultivable diversity of human faeces was developed and used to determine: (i) the initial cultivable LAB strain diversity in the human gut, and (ii) the fate of two Lactobacillus strains (Lactobacillus salivarius NCIMB 30211 and Lactobacillus acidophilus NCIMB 30156) contained within a capsule that was administered in a small-scale human feeding study. The L. salivarius strain was not cultivated from the faeces of any of the 12 volunteers prior to capsule administration, but appeared post-feeding in four. Strains matching the L. acidophilus NCIMB 30156 feeding strain were found in the faeces of three volunteers prior to consumption; after taking the Lactobacillus capsule, 10 of the 12 volunteers were culture positive for this strain. The appearance of both Lactobacillus strains during capsule consumption was statistically significant (p < 0.05). Conclusion We have shown that genetic strain typing of the cultivable human gut microbiota can be evaluated using a high

  7. Growth and Survival of Some Probiotic Strains in Simulated Ice Cream Conditions

    NASA Astrophysics Data System (ADS)

    Homayouni, A.; Ehsani, M. R.; Azizi, A.; Razavi, S. H.; Yarmand, M. S.

    A Completely Randomized Design (CRD) experiment was applied in triplicates to evaluate the survival of four probiotic strains in simulated ice cream conditions. The growth and survival rate of these probiotic strains (Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium longum) in varying amount of sucrose (10, 15, 20 and 25%), oxygen scavenging components (0.05% L-cysteine and 0.05% L-ascorbate) and temperatures (4 and -20°C) during different periods of time (1, 2 and 3 months) were evaluated in MRS-broth medium. Optical density at 580 nm was used to measure growth. Lactobacilli strains proved to be highly resistant in comparison with Biffidobacteria strains. The viable cell number of Lactobacillus casei in different sucrose concentrations, different oxidoreduction potentials and refrigeration temperature was 1x1010, 2x108 and 5x107 cfu mL-1, respectively. Growth and survival rate of Lactobacillus casei showed to be the highest.

  8. Immune modulation of blood leukocytes in humans by lactic acid bacteria: criteria for strain selection.

    PubMed

    Schiffrin, E J; Brassart, D; Servin, A L; Rochat, F; Donnet-Hughes, A

    1997-08-01

    Lactic acid bacteria in food can transiently colonize the intestine and exert beneficial effects (probiotic). Survival during intestinal transit or adhesion to epithelium or both seem to be important for modifying the host's immune reactivity. Because Lactobacillus acidophilus strain La1 is adherent to enterocytes in vitro, we hypothesize that contact with immune cells may occur in vivo. However, Bifidobacterium bifidum strain Bb12, which shows high fecal colonization, is another potential immunomodulator. Twenty-eight volunteers were divided into two groups and given a fermented product containing one of the two strains. Lymphocyte subsets and leukocyte phagocytic activity were studied in blood. No modifications were detected in lymphocyte subsets. In contrast, phagocytosis of Escherichia coli ssp. was enhanced in both groups (P < 0.001 for both). Bacterial adhesion to enterocytes, fecal colonization, or both seem to be valuable selection criteria for immunomodulation. Antiinfective mechanisms of defense can be enhanced after ingestion of specific lactic acid bacteria strains. PMID:9250141

  9. Real-time analysis of metabolic activity within Lactobacillus acidophilus by phasor fluorescence lifetime imaging microscopy of NADH.

    PubMed

    Torno, Keenan; Wright, Belinda K; Jones, Mark R; Digman, Michelle A; Gratton, Enrico; Phillips, Michael

    2013-04-01

    Nicotinamide adenine dinucleotide (NADH) is an endogenous fluorescent molecule commonly used as a metabolic biomarker. Fluorescence lifetime imaging microscopy (FLIM) is a method in which the fluorescence decay is measured at each pixel of an image. While the fluorescence spectrum of free and protein-bound NADH is very similar, free and protein-bound NADH display very different decay profiles. Therefore, FLIM can provide a way to distinguish free/bound NADH at the level of single bacteria within biological samples. The phasor technique is a graphical method to analyse the entire image and to produce a histogram of pixels with different decay profile. In this study, NADH fluorescence decay profiles within Lactobacillus acidophilus samples treated using different protocols indicated discernible variations. Clear distinctions between fluorescence decay profiles of NADH in samples of artificially heightened metabolic activity in comparison to those of samples lacking an accessible carbon source were obtained. PMID:23233088

  10. Advancing the use of Lactobacillus acidophilus surface layer protein A for the treatment of intestinal disorders in humans.

    PubMed

    Sahay, Bikash; Ge, Yong; Colliou, Natacha; Zadeh, Mojgan; Weiner, Chelsea; Mila, Ashley; Owen, Jennifer L; Mohamadzadeh, Mansour

    2015-01-01

    Intestinal immunity is subject to complex and fine-tuned regulation dictated by interactions of the resident microbial community and their gene products with host innate cells. Deterioration of this delicate process may result in devastating autoinflammatory diseases, including inflammatory bowel disease (IBD), which primarily comprises Crohn's disease (CD) and ulcerative colitis (UC). Efficacious interventions to regulate proinflammatory signals, which play critical roles in IBD, require further scientific investigation. We recently demonstrated that rebalancing intestinal immunity via the surface layer protein A (SlpA) from Lactobacillus acidophilus NCFM potentially represents a feasible therapeutic approach to restore intestinal homeostasis. To expand on these findings, we established a new method of purifying bacterial SlpA, a new SlpA-specific monoclonal antibody, and found no SlpA-associated toxicity in mice. Thus, these data may assist in our efforts to determine the immune regulatory efficacy of SlpA in humans. PMID:26647142

  11. Use of a continuous-culture biofilm system to study the antimicrobial susceptibilities of Gardnerella vaginalis and Lactobacillus acidophilus.

    PubMed

    Muli, F; Struthers, J K

    1998-06-01

    Gardnerella vaginalis and Lactobacillus acidophilus have been shown to grow to high titers in a simple biofilm system. This system was used in the present investigation to compare the biofilm-eradicating concentrations (BECs) of amoxicillin, clindamycin, erythromycin, and metronidazole to standard tube MIC and minimum bactericidal concentration (MBC) results. With the lactobacillus, the BEC/tube MBC ratio was at least 16:1, while for G. vaginalis the ratio varied from 2:1 to 512:1. The simple continuous-culture system used in the present investigation is ideal for investigating the BEC for bacteria involved in complex ecological situations such as bacterial vaginosis and may be useful for the identification of the most effective and selective antibiotic therapy. PMID:9624489

  12. Peripheral Light-Harvesting LH2 Complex Can Be Assembled in Cells of Nonsulfur Purple Bacterium Rhodoblastus acidophilus without Carotenoids.

    PubMed

    Bol'shakov, M A; Ashikhmin, A A; Makhneva, Z K; Moskalenko, A A

    2015-09-01

    The effect of carotenoids on the assembly of LH2 complex in cells of the purple nonsulfur bacterium Rhodoblastus acidophilus was investigated. For this purpose, the bacterial culture was cultivated with an inhibitor of carotenoid biosynthesis - 71 µM diphenylamine (DPA). The inhibitor decreased the level of biosynthesis of the colored carotenoids in membranes by ~58%. It was found that a large amount of phytoene was accumulated in them. This carotenoid precursor was bound nonspecifically to LH2 complex and did not stabilize its structure. Thermostability testing of the isolated LH2 complex together with analysis of carotenoid composition revealed that the population of this complex was heterogeneous with respect to carotenoid composition. One fraction of the LH2 complex with carotenoid content around 90% remains stable and was not destroyed under heating for 15 min at 50°C. The other fraction of LH2 complex containing on average less than one molecule of carotenoid per complex was destroyed under heating, forming a zone of free pigments (and polypeptides). The data suggest that a certain part of the LH2 complexes is assembled without carotenoids in cells of the nonsulfur bacterium Rbl. acidophilus grown with DPA. These data contradict the fact that the LH2 complex from nonsulfur bacteria cannot be assembled without carotenoids, but on the other hand, they are in good agreement with the results demonstrated in our earlier studies of the sulfur bacteria Allochromatium minutissimum and Ectothiorhodospira haloalkaliphila. Carotenoidless LH2 complex was obtained from these bacteria with the use of DPA (Moskalenko, A. A., and Makhneva, Z. K. (2012) J. Photochem. Photobiol., 108, 1-7; Ashikhmin, A., et al. (2014) Photosynth. Res., 119, 291-303). PMID:26555469

  13. Lactobacillus acidophilus attenuates Aeromonas hydrophila induced cytotoxicity in catla thymus macrophages by modulating oxidative stress and inflammation.

    PubMed

    Patel, Bhakti; Kumar, Premranjan; Banerjee, Rajanya; Basu, Madhubanti; Pal, Arttatrana; Samanta, Mrinal; Das, Surajit

    2016-07-01

    The pathogenesis of Aeromonas hydrophila, a potent fish pathogen, is attributed to its ability to cause motile aeromonad septicaemia leading to apoptosis in a myriad of fish species, including freshwater carp Catla catla. However, the underlying mechanism of antagonistic activity of probiotics against A. hydrophila induced apoptosis is not elucidated due to lack of appropriate in-vitro models. This study reported that the exposure of catla thymus macrophages (CTM) to A. hydrophila markedly induced cellular injuries as evidenced by elevated levels of reactive oxygen species (ROS), reactive nitrogen species (RNS), increased apoptosis, DNA damage and decreased cellular viability. Flow cytometry analysis and Annexin-V/propidium iodide assay further confirmed increased ROS positive cells leading to cell death after infection. The quantitative real-time PCR analysis, also revealed upregulation of inducible nitric-oxide synthase (iNOS), pro-inflammatory cytokine (TNFα), cyclooxygenase2 (COX-2) and downregulation of anti-inflammatory cytokine (IL-10). Pretreatment of cells with probiotic, Lactobacillus acidophilus attenuated A. hydrophila induced apoptosis as evident from the decrease in the levels of ROS, RNS and DNA damage. Significant increase (P≤0.05) in expression of TNFα and IL-10 and decrease in iNOS and COX-2 was observed on probiotic stimulation. In-vivo study using catla fingerlings confirmed similar pattern of ROS, iNOS, NO production and cytokine expression in thymus. This study provides a comprehensive insight into the mechanistic basis of L. acidophilus induced macrophage mediated inflammatory response against A. hydrophila in CTM cells. Further, it speculates the possibility of using cost-effective in-vitro models for screening probiotic candidates of therapeutic potential in aquaculture industry. PMID:27262084

  14. Crystal structure of α-galactosidase from Lactobacillus acidophilus NCFM: insight into tetramer formation and substrate binding.

    PubMed

    Fredslund, Folmer; Hachem, Maher Abou; Larsen, René Jonsgaard; Sørensen, Pernille Gerd; Coutinho, Pedro M; Lo Leggio, Leila; Svensson, Birte

    2011-09-23

    Lactobacillus acidophilus NCFM is a probiotic bacterium known for its beneficial effects on human health. The importance of α-galactosidases (α-Gals) for growth of probiotic organisms on oligosaccharides of the raffinose family present in many foods is increasingly recognized. Here, the crystal structure of α-Gal from L. acidophilus NCFM (LaMel36A) of glycoside hydrolase (GH) family 36 (GH36) is determined by single-wavelength anomalous dispersion. In addition, a 1.58-Å-resolution crystallographic complex with α-d-galactose at substrate binding subsite -1 was determined. LaMel36A has a large N-terminal twisted β-sandwich domain, connected by a long α-helix to the catalytic (β/α)(8)-barrel domain, and a C-terminal β-sheet domain. Four identical monomers form a tightly packed tetramer where three monomers contribute to the structural integrity of the active site in each monomer. Structural comparison of LaMel36A with the monomeric Thermotoga maritima α-Gal (TmGal36A) reveals that O2 of α-d-galactose in LaMel36A interacts with a backbone nitrogen in a glycine-rich loop of the catalytic domain, whereas the corresponding atom in TmGal36A is from a tryptophan side chain belonging to the N-terminal domain. Thus, two distinctly different structural motifs participate in substrate recognition. The tetrameric LaMel36A furthermore has a much deeper active site than the monomeric TmGal36A, which possibly modulates substrate specificity. Sequence analysis of GH36, inspired by the observed structural differences, results in four distinct subgroups having clearly different active-site sequence motifs. This novel subdivision incorporates functional and architectural features and may aid further biochemical and structural analyses within GH36. PMID:21827767

  15. Enzymology and Structure of the GH13_31 Glucan 1,6-α-Glucosidase That Confers Isomaltooligosaccharide Utilization in the Probiotic Lactobacillus acidophilus NCFM

    PubMed Central

    Møller, Marie S.; Fredslund, Folmer; Majumder, Avishek; Nakai, Hiroyuki; Poulsen, Jens-Christian N.; Lo Leggio, Leila; Svensson, Birte

    2012-01-01

    Isomaltooligosaccharides (IMO) have been suggested as promising prebiotics that stimulate the growth of probiotic bacteria. Genomes of probiotic lactobacilli from the acidophilus group, as represented by Lactobacillus acidophilus NCFM, encode α-1,6 glucosidases of the family GH13_31 (glycoside hydrolase family 13 subfamily 31) that confer degradation of IMO. These genes reside frequently within maltooligosaccharide utilization operons, which include an ATP-binding cassette transporter and α-glucan active enzymes, e.g., maltogenic amylases and maltose phosphorylases, and they also occur separated from any carbohydrate transport or catabolism genes on the genomes of some acidophilus complex members, as in L. acidophilus NCFM. Besides the isolated locus encoding a GH13_31 enzyme, the ABC transporter and another GH13 in the maltooligosaccharide operon were induced in response to IMO or maltotetraose, as determined by reverse transcription-PCR (RT-PCR) transcriptional analysis, suggesting coregulation of α-1,6- and α-1,4-glucooligosaccharide utilization loci in L. acidophilus NCFM. The L. acidophilus NCFM GH13_31 (LaGH13_31) was produced recombinantly and shown to be a glucan 1,6-α-glucosidase active on IMO and dextran and product-inhibited by glucose. The catalytic efficiency of LaGH13_31 on dextran and the dextran/panose (trisaccharide) efficiency ratio were the highest reported for this class of enzymes, suggesting higher affinity at distal substrate binding sites. The crystal structure of LaGH13_31 was determined to a resolution of 2.05 Å and revealed additional substrate contacts at the +2 subsite in LaGH13_31 compared to the GH13_31 from Streptococcus mutans (SmGH13_31), providing a possible structural rationale to the relatively high affinity for dextran. A comprehensive phylogenetic and activity motif analysis mapped IMO utilization enzymes from gut microbiota to rationalize preferential utilization of IMO by gut residents. PMID:22685275

  16. Enzymology and structure of the GH13_31 glucan 1,6-α-glucosidase that confers isomaltooligosaccharide utilization in the probiotic Lactobacillus acidophilus NCFM.

    PubMed

    Møller, Marie S; Fredslund, Folmer; Majumder, Avishek; Nakai, Hiroyuki; Poulsen, Jens-Christian N; Lo Leggio, Leila; Svensson, Birte; Abou Hachem, Maher

    2012-08-01

    Isomaltooligosaccharides (IMO) have been suggested as promising prebiotics that stimulate the growth of probiotic bacteria. Genomes of probiotic lactobacilli from the acidophilus group, as represented by Lactobacillus acidophilus NCFM, encode α-1,6 glucosidases of the family GH13_31 (glycoside hydrolase family 13 subfamily 31) that confer degradation of IMO. These genes reside frequently within maltooligosaccharide utilization operons, which include an ATP-binding cassette transporter and α-glucan active enzymes, e.g., maltogenic amylases and maltose phosphorylases, and they also occur separated from any carbohydrate transport or catabolism genes on the genomes of some acidophilus complex members, as in L. acidophilus NCFM. Besides the isolated locus encoding a GH13_31 enzyme, the ABC transporter and another GH13 in the maltooligosaccharide operon were induced in response to IMO or maltotetraose, as determined by reverse transcription-PCR (RT-PCR) transcriptional analysis, suggesting coregulation of α-1,6- and α-1,4-glucooligosaccharide utilization loci in L. acidophilus NCFM. The L. acidophilus NCFM GH13_31 (LaGH13_31) was produced recombinantly and shown to be a glucan 1,6-α-glucosidase active on IMO and dextran and product-inhibited by glucose. The catalytic efficiency of LaGH13_31 on dextran and the dextran/panose (trisaccharide) efficiency ratio were the highest reported for this class of enzymes, suggesting higher affinity at distal substrate binding sites. The crystal structure of LaGH13_31 was determined to a resolution of 2.05 Å and revealed additional substrate contacts at the +2 subsite in LaGH13_31 compared to the GH13_31 from Streptococcus mutans (SmGH13_31), providing a possible structural rationale to the relatively high affinity for dextran. A comprehensive phylogenetic and activity motif analysis mapped IMO utilization enzymes from gut microbiota to rationalize preferential utilization of IMO by gut residents. PMID:22685275

  17. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1997-01-01

    Logarithmic strain is the preferred measure of strain used by materials scientists, who typically refer to it as the "true strain." It was Nadai who gave it the name "natural strain," which seems more appropriate. This strain measure was proposed by Ludwik for the one-dimensional extension of a rod with length l. It was defined via the integral of dl/l to which Ludwik gave the name "effective specific strain." Today, it is after Hencky, who extended Ludwik's measure to three-dimensional analysis by defining logarithmic strains for the three principal directions.

  18. Microencapsulation of Lactobacillus acidophilus NCIMB 701748 in matrices containing soluble fibre by spray drying: Technological characterization, storage stability and survival after in vitro digestion☆

    PubMed Central

    Yonekura, Lina; Sun, Han; Soukoulis, Christos; Fisk, Ian

    2014-01-01

    We evaluated sodium alginate, chitosan and hydroxypropyl methylcellulose (HPMC) as co-encapsulants for spray dried Lactobacillus acidophilus NCIMB 701748 by assessing their impact on cell viability and physicochemical properties of the dried powders, viability over 35 days of storage at 25 °C and survival after simulated digestion. Fibres were added to a control carrier medium containing whey protein concentrate, d-glucose and maltodextrin. Sodium alginate and HPMC did not affect cell viability but chitosan reduced viable counts in spray dried powders, as compared to the control. Although chitosan caused large losses of viability during spray-drying, these losses were counteracted by the excellent storage stability compared to control, sodium alginate and HPMC, and the overall effect became positive after the 35-day storage. Chitosan also improved survival rates in simulated GI conditions, however no single fibre could improve L. acidophilus NCIMB 701748 viability in all steps from production through storage and digestion. PMID:24748900

  19. Studying the Stability of S-Layer Protein of Lactobacillus Acidophilus ATCC 4356 in Simulated Gastrointestinal Fluids Using SDS-PAGE and Circular Dichroism

    PubMed Central

    Eslami, Neda; Kermanshahi, Rouha Kasra; Erfan, Mohammad

    2013-01-01

    Crystalline arrays of proteinaceous subunits forming surface layers (S-layers) are now recognized as one of the most common outermost cell envelope components of prokaryotic organisms. The surface layer protein of Lactobacillus acidophilus ATCC4356 is composed of a single species of protein of apparent molecular weight of 43-46 KDa. Considering the Lactobacillus acidophilus ATCC4356 having the S-layer is stable in harsh gastrointestinal (GI) conditions, a protective role against destructive GI factors which has been proposed for these nanostructures. It opens interesting perspectives in the using and development of this S-layer as a protective coat for oral administration of unstable drug nanocarriers. To achieve this goal, it is necessary to study the in-vitro stability of the S-layers in the simulated gastrointestinal fluids (SGIF). This study was planned to evaluate the in-vitro stability of the extracted S-layer protein of Lactobacillus acidophilus ATCC4356 in SGIF using it as a protective coat in oral drug delivery. Sodium dodecyl sulfate gel electrophoresis (SDS-PAGE) and circular dichroism (CD) spectroscopy were used to study the stability of the S-layer protein incubated in SGIF. Both the SDS-PAGE and CD spectra results showed that Lactobacillus acidophilus ATCC4356 S-layer protein is stable in simulated gastric fluid (SGF) with pH = 2 up to 5 min. It is stable in SGF pH = 3.2 and above it, with and without pepsin. It is also stable in all the simulated intestinal fluids. This S-layer is also stable in all of the simulated intestinal fluids. PMID:24250671

  20. Development and application of a upp-based counterselective gene replacement system for the study of the S-layer protein SlpX of Lactobacillus acidophilus NCFM.

    PubMed

    Goh, Yong Jun; Azcárate-Peril, M Andrea; O'Flaherty, Sarah; Durmaz, Evelyn; Valence, Florence; Jardin, Julien; Lortal, Sylvie; Klaenhammer, Todd R

    2009-05-01

    In silico genome analysis of Lactobacillus acidophilus NCFM coupled with gene expression studies have identified putative genes and regulatory networks that are potentially important to this organism's survival, persistence, and activities in the gastrointestinal tract. Correlation of key genotypes to phenotypes requires an efficient gene replacement system. In this study, use of the upp-encoded uracil phosphoribosyltransferase (UPRTase) of L. acidophilus NCFM was explored as a counterselection marker to positively select for recombinants that have resolved from chromosomal integration of pORI-based plasmids. An isogenic mutant carrying a upp gene deletion was constructed and was resistant to 5-fluorouracil (5-FU), a toxic uracil analog that is also a substrate for UPRTase. A 3.0-kb pORI-based counterselectable integration vector bearing a upp expression cassette, pTRK935, was constructed and introduced into the Deltaupp host harboring the pTRK669 helper plasmid. Extrachromosomal replication of pTRK935 complemented the mutated chromosomal upp allele and restored sensitivity to 5-FU. This host background provides a platform for a two-step plasmid integration and excision strategy that can select for plasmid-free recombinants with either the wild-type or mutated allele of the targeted gene in the presence of 5-FU. The efficacy of the system was demonstrated by in-frame deletion of the slpX gene (LBA0512) encoding a novel 51-kDa secreted protein associated with the S-layer complex of L. acidophilus. The resulting DeltaslpX mutant exhibited lower growth rates, increased sensitivity to sodium dodecyl sulfate, and greater resistance to bile. Overall, this improved gene replacement system represents a valuable tool for investigating the mechanisms underlying the probiotic functionality of L. acidophilus. PMID:19304841

  1. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1995-01-01

    The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures affiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of of the fundamental body-metric tensors of Lodge. These strain and strain-rate measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian state is obtained.

  2. How does the supernatant of Lactobacillus acidophilus affect the proliferation and differentiation activities of rat bone marrow-derived stromal cells?

    PubMed

    Samadikuchaksaraei, A; Gholipourmalekabadi, M; Saberian, M; Abdollahpour Alitappeh, M; Shahidi Delshad, E

    2016-01-01

    Low proliferation rate and unwanted differentiation of bone marrow-derived stromal cells (rBMSCs) during the frequent passages have limited the use of such cells in clinical cell therapy. Recently, the researchers have focused on the effects of the components produced by some bacteria on proliferation of the stem cells. In this study, we discussed the possible effects of the Lactobacillus acidophilus supernatant on proliferation and differentiation of the rBMSCs. For this aim, the cells were isolated from rat bone marrow, characterized by culturing on tissue specific differentiation media and stained. The cells (passage two) were treated with different concentrations of the L. acidophilus supernatant (0, 0.1, 0.3, 0.9, 3, 9 and 30 &mgr;l/ml) for 14 days. The proliferation and differentiation capacity of the cells were then determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT assay) and tissue specific staining. The results showed a positive effect of the supernatant on the cell proliferation in 3 and 9 &mgr;l/ml concentrations, while did not affect the differentiation capacity of the rBMSCs. The current study strongly suggests the L. acidophilus supernatant as an alternative material that could be added to the media with aim of improvement in the proliferation rate of the rBMSCs without affecting their differentiation capacity. PMID:27609467

  3. Transcriptional analysis of genes associated with stress and adhesion in Lactobacillus acidophilus NCFM during the passage through an in vitro gastrointestinal tract model.

    PubMed

    Weiss, G; Jespersen, L

    2010-01-01

    The aim of the present study was to investigate the transcription of genes associated with stress and adhesion in Lactobacillus acidophilus NCFM during the passage through an in vitro gastrointestinal tract model. As acidified milk exerted a protective effect on the bacteria leading to increased survival, the gene expression studies were carried out with pre-inoculation of L. acidophilus NCFM in acidified milk. The induction of the genes encoding the stress-related proteins GroEL, DnaK and ClpP, and adhesion-related genes encoding mucin-binding proteins, fibronectin-binding protein and S-layer was analyzed by real-time PCR. The genes encoding GroEL, DnaK and ClpP were significantly up-regulated (9- to 16-fold) during gastric digestion and declined upon subsequent duodenal digestion. The genes encoding mucin-binding proteins and fibronectin-binding protein were not influenced by saliva and gastric juice, but they were significantly upregulated during incubation in duodenal juice and bile (6- to 7-fold). A significant induction of the gene encoding the S-layer protein was not detected. Our results give a better understanding of the functionality of L. acidophilus NCFM and other probiotics during passage through the gastrointestinal tract; hence, they provide an implementable basis for the selection of prospective probiotic candidates. PMID:20559014

  4. Lactobacillus acidophilus induces a slow but more sustained chemokine and cytokine response in naïve foetal enterocytes compared to commensal Escherichia coli

    PubMed Central

    2010-01-01

    Background The first exposure to microorganisms at mucosal surfaces is critical for immune maturation and gut health. Facultative anaerobic bacteria are the first to colonise the infant gut, and the impact of these bacteria on intestinal epithelial cells (IEC) may be determinant for how the immune system subsequently tolerates gut bacteria. Results To mirror the influence of the very first bacterial stimuli on infant IEC, we isolated IEC from mouse foetuses at gestational day 19 and from germfree neonates. IEC were stimulated with gut-derived bacteria, Gram-negative Escherichia coli Nissle and Gram-positive Lactobacillus acidophilus NCFM, and expression of genes important for immune regulation was measured together with cytokine production. E. coli Nissle and L. acidophilus NCFM strongly induced chemokines and cytokines, but with different kinetics, and only E. coli Nissle induced down-regulation of Toll-like receptor 4 and up-regulation of Toll-like receptor 2. The sensitivity to stimulation was similar before and after birth in germ-free IEC, although Toll-like receptor 2 expression was higher before birth than immediately after. Conclusions In conclusion, IEC isolated before gut colonisation occurs at birth, are highly responsive to stimulation with gut commensals, with L. acidophilus NCFM inducing a slower, but more sustained response than E. coli Nissle. E. coli may induce intestinal tolerance through very rapid up-regulation of chemokine and cytokine genes and down-regulation of Toll-like receptor 4, while regulating also responsiveness to Gram-positive bacteria. PMID:20085657

  5. Short communication: Viability of culture organisms in honey-enriched acidophilus-bifidus-thermophilus (ABT)-type fermented camel milk.

    PubMed

    Varga, L; Süle, J; Nagy, P

    2014-11-01

    The aim of this research was to monitor the survival during refrigerated storage of Lactobacillus acidophilus LA-5 (A), Bifidobacterium animalis ssp. lactis BB-12 (B), and Streptococcus thermophilus CHCC 742/2130 (T) in cultured dairy foods made from camel and, for comparison, cow milks supplemented with black locust (Robinia pseudoacacia L.) honey and fermented by an acidophilus-bifidus-thermophilus (ABT)-type culture. Two liters of dromedary camel milk and 2 L of cow milk were heated to 90 °C and held for 10 min, then cooled to 40 °C. One half of both types of milk was fortified with black locust honey at the rate of 5.0% (wt/vol), whereas the other half was devoid of honey and served as a control. The camel and cow milks with and without honey were subsequently inoculated with ABT-5 culture and were fermented at 37 °C until a pH value of 4.6 was reached. Thereafter, the probiotic fermented milks were cooled to 15 °C in ice water and were each separated into 18 fractions that were transferred in sterile, tightly capped centrifuge tubes. After 24 h of cooling at 8 °C (d 0), the samples were stored at refrigeration temperature (4 °C). Three tubes of all 4 products (i.e., fermented camel and cow milks with and without honey) were taken at each sampling time (i.e., following 0, 7, 14, 21, 28, and 35 d of storage), and the counts of characteristic microorganisms and those of certain spoilage microbes (yeasts, molds, coliforms, Escherichia coli) were enumerated. The entire experimental program was repeated twice. The results showed that addition of black locust honey at 5% to heat-treated camel and cow milks did not influence the growth and survival of starter streptococci during production and subsequent refrigerated storage of fermented ABT milks. In contrast, honey improved retention of viability of B. animalis ssp. lactis BB-12 in the camel milk-based product during storage at 4 °C up to 5 wk. No spoilage organisms were detected in any of the samples tested

  6. The hsp 16 gene of the probiotic Lactobacillus acidophilus is differently regulated by salt, high temperature and acidic stresses, as revealed by reverse transcription quantitative PCR (qRT-PCR) analysis.

    PubMed

    Capozzi, Vittorio; Arena, Mattia Pia; Crisetti, Elisabetta; Spano, Giuseppe; Fiocco, Daniela

    2011-01-01

    Small heat shock proteins (sHsps) are ubiquitous conserved chaperone-like proteins involved in cellular proteins protection under stressful conditions. In this study, a reverse transcription quantitative PCR (RT-qPCR) procedure was developed and used to quantify the transcript level of a small heat shock gene (shs) in the probiotic bacterium Lactobacillus acidophilus NCFM, under stress conditions such as heat (45 °C and 53 °C), bile (0.3% w/v), hyperosmosis (1 M and 2.5 M NaCl), and low pH value (pH 4). The shs gene of L. acidophilus NCFM was induced by salt, high temperature and acidic stress, while repression was observed upon bile stress. Analysis of the 5' noncoding region of the hsp16 gene reveals the presence of an inverted repeat (IR) sequence (TTAGCACTC-N9-GAGTGCTAA) homologue to the controlling IR of chaperone expression (CIRCE) elements found in the upstream regulatory region of Gram-positive heat shock operons, suggesting that the hsp16 gene of L. acidophilus might be transcriptionally controlled by HrcA. In addition, the alignment of several small heat shock proteins identified so far in lactic acid bacteria, reveals that the Hsp16 of L. acidophilus exhibits a strong evolutionary relationship with members of the Lactobacillus acidophilus group. PMID:21954366

  7. Interaction of Aeromonas Strains with Lactic Acid Bacteria via Caco-2 Cells

    PubMed Central

    Hatje, E.; Neuman, C.

    2014-01-01

    The genus Aeromonas includes some species that have now been identified as human pathogens of significant medical importance. We investigated the ability of 13 selected Aeromonas strains belonging to nine species isolated from clinical cases (n = 5), environmental waters (n = 5), and fish (n = 3) to adhere to and translocate Caco-2 cells in the absence and presence of two lactic acid bacteria (LAB), i.e., Lactobacillus acidophilus and Bifidobacterium breve. Aeromonas isolates were also assessed for their cytotoxicity, the presence of virulence genes, and hemolysin production. Among the clinical isolates, one strain of Aeromonas veronii biovar veronii and two strains of Aeromonas hydrophila carried cytotoxin (act), heat-labile toxin (alt), hemolysin (hlyA), and aerolysin (aerA) genes, were cytotoxic to Vero cells, produced hemolysin, and showed higher adherence to Caco-2 cells. In contrast, this was seen in only one environmental strain, a strain of A. veronii biovar sobria. When Aeromonas strains were coinoculated with LAB onto Caco-2 cells, their level of adhesion was reduced. However, their rate of translocation in the presence of LAB increased and was significantly (P < 0.05) higher among fish strains. We suggest that either the interaction between Aeromonas and LAB strains could have a detrimental effect on the Caco-2 cells, allowing the Aeromonas to translocate more readily, or the presence of the LAB stimulated the Aeromonas strains to produce more toxins and/or increase their translocation rate. PMID:24242240

  8. A novel unsaturated fatty acid hydratase toward C16 to C22 fatty acids from Lactobacillus acidophilus

    PubMed Central

    Hirata, Akiko; Kishino, Shigenobu; Park, Si-Bum; Takeuchi, Michiki; Kitamura, Nahoko; Ogawa, Jun

    2015-01-01

    Hydroxy FAs, one of the gut microbial metabolites of PUFAs, have attracted much attention because of their various bioactivities. The purpose of this study was to identify lactic acid bacteria with the ability to convert linoleic acid (LA) to hydroxy FAs. A screening process revealed that a gut bacterium, Lactobacillus acidophilus NTV001, converts LA mainly into 13-hydroxy-cis-9-octadecenoic acid and resulted in the identification of the hydratase responsible, fatty acid hydratase 1 (FA-HY1). Recombinant FA-HY1 was purified, and its enzymatic characteristics were investigated. FA-HY1 could convert not only C18 PUFAs but also C20 and C22 PUFAs. C18 PUFAs with a cis carbon-carbon double bond at the Δ12 position were converted into the corresponding 13-hydroxy FAs. Arachidonic acid and DHA were converted into the corresponding 15-hydroxy FA and 14-hydroxy FA, respectively. To the best of our knowledge, this is the first report of a bacterial FA hydratase that can convert C20 and C22 PUFAs into the corresponding hydroxy FAs. These novel hydroxy FAs produced by using FA-HY1 should contribute to elucidating the bioactivities of hydroxy FAs. PMID:25966711

  9. Yogurt containing bioactive molecules produced by Lactobacillus acidophilus La-5 exerts a protective effect against enterohemorrhagic Escherichia coli in mice.

    PubMed

    Zeinhom, Mohamed; Tellez, Angela M; Delcenserie, Veronique; El-Kholy, A M; El-Shinawy, S H; Griffiths, Mansel W

    2012-10-01

    An active fraction extracted from Lactobacillus acidophilus La5 cell-free spent medium (LAla-5AF) was incorporated in a dairy matrix and tested to assess its antivirulent effect against enterohemorrhagic Escherichia coli (EHEC). Mice in experimental groups were fed for 4 days with yogurt supplemented with LAla-5AF. On the fifth day, mice were challenged with a single dose (10(7) CFU per mouse) of E. coli O157:H7. The clinical manifestations of the infection were significantly less severe in mice fed the yogurt supplemented with LAla-5AF. EHEC attachment and colonization was attenuated by LAla-5AF. Tumor necrosis factor alpha production was down-regulated, which might indicate a protective effect in the kidney during EHEC infection. To investigate the mechanisms associated with the in vivo effects observed, LAla-5AF was tested by reverse transcription real-time PCR to confirm its effects on the expression of several virulence genes of EHEC O157. The results showed that these fractions were able to down-regulate several virulence genes of EHEC, including stxB2, qseA, luxS, tir, ler, eaeA, and hlyB. PMID:23043828

  10. Differential proteome and cellular adhesion analyses of the probiotic bacterium Lactobacillus acidophilus NCFM grown on raffinose - an emerging prebiotic.

    PubMed

    Celebioglu, Hasan Ufuk; Ejby, Morten; Majumder, Avishek; Købler, Carsten; Goh, Yong Jun; Thorsen, Kristian; Schmidt, Bjarne; O'Flaherty, Sarah; Abou Hachem, Maher; Lahtinen, Sampo J; Jacobsen, Susanne; Klaenhammer, Todd R; Brix, Susanne; Mølhave, Kristian; Svensson, Birte

    2016-05-01

    Whole cell and surface proteomes were analyzed together with adhesive properties of the probiotic bacterium Lactobacillus acidophilus NCFM (NCFM) grown on the emerging prebiotic raffinose, exemplifying a synbiotic. Adhesion of NCFM to mucin and intestinal HT-29 cells increased three-fold after culture with raffinose versus glucose, as also visualized by scanning electron microscopy. Comparative proteomics using 2D-DIGE showed 43 unique proteins to change in relative abundance in whole cell lysates from NCFM grown on raffinose compared to glucose. Furthermore, 14 unique proteins in 18 spots of the surface subproteome underwent changes identified by differential 2DE, including elongation factor G, thermostable pullulanase, and phosphate starvation inducible stress-related protein increasing in a range of +2.1 - +4.7 fold. By contrast five known moonlighting proteins decreased in relative abundance by up to -2.4 fold. Enzymes involved in raffinose catabolism were elevated in the whole cell proteome; α-galactosidase (+13.9 fold); sucrose phosphorylase (+5.4 fold) together with metabolic enzymes from the Leloir pathway for galactose utilization and the glycolysis; β-galactosidase (+5.7 fold); galactose (+2.9/+3.1 fold) and fructose (+2.8 fold) kinases. The insights at the molecular and cellular levels contributed to the understanding of the interplay of a synbiotic composed of NCFM and raffinose with the host. PMID:26959526

  11. Potential of functional strains, isolated from traditional Maasai milk, as starters for the production of fermented milks.

    PubMed

    Patrignani, Francesca; Lanciotti, Rosalba; Mathara, Julius Maina; Guerzoni, Maria Elisabetta; Holzapfel, Wilhelm H

    2006-03-01

    The purpose of this research was the evaluation of technological features and of the ability of functional LAB strains with desirable sensory characteristics, to produce fermented milk. Eight strains of Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus paracasei and Lactococcus lactis, isolated from Maasai traditional fermented milk in Kenya and previously tested for their probiotic properties, were selected for this investigation. Technological features such as growth kinetics in fresh heat-treated whole milk medium and survival in the final product during storage at 4 degrees C, were studied. The strains Lb. acidophilus BFE 6,059, Lb. paracasei BFE 5,264 and Lc. lactis BFE 6,049 showed the best potential and were thus selected for use as starter cultures in further trials with the objective to improve their technological performance and to optimise the sensory features of fermented milk obtained. The effects of fat (F), non-fat milk solids (S) and fermentation temperature (T), modulated according to a Central Composite Design, on fermentation rates and viability losses during refrigerated storage of the chosen starters, and on product texture parameters, were studied. From the data analysis, it was possible to select optimum conditions for enhancing positive sensory traits of final products and for improving the survival of these potentially probiotic cultures. PMID:16271787

  12. Probiotics cultures in animal feed: Effects on ruminal fermentation, immune responses, and resistance to infectious diseases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effects of probiotics included in dairy cattle and mice feed on ruminal fermentation, immune responses, and resistance to Johne’s disease. To unveil the underlying mechanisms, dairy cattle were either fed Bovamine (1.04 x 10**9 cfu of Lactobacillus acidophilus NP51 plus 2.04 x 10**...

  13. Strain Gage

    NASA Technical Reports Server (NTRS)

    1995-01-01

    HITEC Corporation developed a strain gage application for DanteII, a mobile robot developed for NASA. The gage measured bending forces on the robot's legs and warned human controllers when acceptable forces were exceeded. HITEC further developed the technology for strain gage services in creating transducers out of "Indy" racing car suspension pushrods, NASCAR suspension components and components used in motion control.

  14. 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

    2011-10-01

    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. PMID:21807435

  15. Egg quality and productive performance of laying hens fed different levels of skimmed milk powder added to a diet containing Lactobacillus acidophilus.

    PubMed

    Cesari, V; Mangiagalli, M G; Giardini, A; Galimberti, P; Carteri, S; Gallazzi, D; Toschi, I

    2014-05-01

    The current trial was carried out on a commercial poultry farm to study the effect of skim milk powder (SMP) added to a diet containing Lactobacillus acidophilus on performance and egg quality of laying hens from 20 to 49 wk of age. A total of 2,400 Hy-Line W-36 laying hens were housed in 600 unenriched cages (4 hens each) located over 4 tier levels. Animals were assigned to 1 of 3 experimental treatments (0, 3, and 4). The laying hens assigned to treatments 3 and 4 received a diet enriched respectively with 3 and 4% SMP, whereas the animals in treatment 0 were fed a diet without SMP. All diets, moreover, were supplemented with L. acidophilus D2/CSL. Hen performance was determined throughout the experimental period and egg quality was measured on 30 eggs per treatment every week. Results showed that productive performance in terms of egg production, egg weight, and feed conversion ratio was not influenced by SMP at 3 or 4% of the diet. Egg quality was significantly affected by SMP included at 3 or 4% of the diet. Eggs from treatments 3 and 4, in fact, displayed higher shell thickness than those from treatment 0 (P < 0.0001). Likewise, specific gravity, Haugh unit, and shell percentage were significantly affected by the addition of SMP. In conclusion, in our study, SMP added to a diet containing L. acidophilus had no significant effects on the productive parameters of hens during the laying period, whereas significant improvements were found in certain egg quality characteristics. PMID:24795312

  16. Antimicrobial efficacy of Acacia nilotica, Murraya koenigii (L.) Sprengel, Eucalyptus hybrid, Psidium guajava extracts and their combination on Streptococcus mutans and Lactobacillus acidophilus

    PubMed Central

    Chandra Shekar, B. R.; Nagarajappa, Ramesh; Jain, Richa; Singh, Rupal; Thakur, Rupesh; Shekar, Suma

    2016-01-01

    Background: The aim of this in vitro study was to assess antimicrobial efficacy of Acacia nilotica, Murraya koenigii (L.) Sprengel, Eucalyptus hybrid, Psidium guajava extracts, and their combination on Streptococcus mutans and Lactobacillus acidophilus. Materials and Methods: The branches of four plants were collected, identified, and authenticated by a taxonomist. The plants were rinsed in water, healthy leaves were separated and shade dried over a period of 3-4 weeks. Soxhlet apparatus using ethanol was employed for extraction procedure. The combinations of plant extracts were prepared by mixing equal quantities of 10% solutions of each of these extracts. 0.2% chlorhexidine and dimethyl sulfoxide were used as positive and negative controls, respectively. The antimicrobial efficacy testing was done using agar well-diffusion method under anaerobic conditions. The mean diameter of inhibition zone was computed and compared between different categories using one-way analysis of variance and Tukey's post-hoc test. A qualitative assay was carried out to identify the various phytochemical constituents in the plants. The data was assessed by SPSS version 20. The statistical significance was fixed at 0.05. Results: All the plants extracts and their combinations inhibited S. mutans and L. acidophilus. However, the quadruple combination of A. nilotica + M. koenigii (L.) Sprengel + Eucalyptus hybrid + P. guajava produced the maximum inhibition zone (23.5 ± 2.2 mm) against S. mutans. Although, 0.2% chlorhexidine produced the highest inhibition zone against L. acidophilus (18.8 ± 1.2 mm), A. nilotica extract produced maximum inhibition among the various plant extracts and their combinations (14.1 ± 1.8 mm). Conclusion: All the individual plant extracts and their combinations were effective against S. mutans and L. acidophilus. These could be tried as herbal alternates to chlorhexidine. However, these in vitro results have to be further evaluated for any toxicity of the

  17. Preservative effect of food-based fermentate from Lactobacillus acidophilus NX2-6 on chilled pork patties.

    PubMed

    Zhang, Qianying; Lu, Yingjian; Liu, Xiaoxi; Bie, Xiaomei; Lv, Fengxia; Lu, Zhaoxin

    2014-03-01

    The food-based fermentate (FBF) from Lactobacillus acidophilus NX2-6 has a broad-spectrum antibacterial activity but has not previously been reported as a food preservative. Experiments were conducted to assess its application as a preservative in pork patties. The effect of freeze-dried FBF on the microbiological parameters, physicochemical changes, and sensory evaluations of chilled pork patties stored for 15 days at 4°C was investigated. The five treatments evaluated included a control (meat only), nisin (meat plus 0.5% nisin), L.1 (meat plus 2% freeze-dried FBF), L.2 (meat plus 4% freeze-dried FBF), and L.3 (meat plus 8% freeze-dried FBF). The results showed that freeze-dried FBF could significantly (P < 0.05) inhibit aerobic bacteria, coliforms, Pseudomonas spp., and lactic acid bacteria, with the lowest microbial counts observed in L.3. The addition of freeze-dried FBF resulted in concentration-dependent decreases in total volatile basic nitrogen values and pH values but increases in lipid oxidation and color instability. Based on the criteria regarding microbiological and physicochemical parameters, the shelf life was 9 to 12 days for L.1, 12 to 15 days for L.2, and over 15 days for L.3, while the shelf-lives of the control and nisin treatments were 3 to 6 days, indicating that freeze-dried FBF could extend the shelf life by more than 3 days. Although the shelf life of L.1 was shorter than those of L.2 and L.3, the appearance of L.1 was much better than those of L.2 and L.3. Overall, treatment with 4 or 8% freeze-dried FBF could be improved if color and lipid oxidation could be improved by appropriate stabilizers, and a lower concentration (2%) of freeze-dried FBF has great potential as a natural and safe preservative in chilled pork patties. PMID:24674438

  18. Gut microbiota of healthy elderly NSAID users is selectively modified with the administration of Lactobacillus acidophilus NCFM and lactitol.

    PubMed

    Björklund, Marika; Ouwehand, Arthur C; Forssten, Sofia D; Nikkilä, Janne; Tiihonen, Kirsti; Rautonen, Nina; Lahtinen, Sampo J

    2012-08-01

    Ageing changes gut microbiota composition and alters immune system function. Probiotics, prebiotics and synbiotics may improve the health status of elderly individuals by modifying the intestinal environment and the microbiota composition, and by stimulating the immune system. In this work, we studied the effects of synbiotic supplementation on the gut microbiota of healthy elderly volunteers. Fifty-one elders were randomly assigned to consume either a synbiotic dietary supplement or a placebo in addition to their usual diet for a 2-week period. The synbiotic product consisted of the probiotic Lactobacillus acidophilus NCFM and the prebiotic lactitol and was ingested twice a day, with a total daily dose of 10 g lactitol and 2 × 10(10) cells of probiotic bacteria. Before, during and after the intervention period fecal quantities of six phylogenetic bacterial groups were determined using quantitative PCR, and relative changes in total microbiota composition were assessed by percent guanine-plus-cytosine profiling. The microbiota profiles showed certain relative changes within the microbial community, and indicated an increase of bifidobacteria levels during synbiotic supplementation. Quantification by PCR confirmed the in changes in the microbiota composition; for example increases in total levels of endogenous bifidobacteria and lactobacilli were recorded. Throughout the 6-week study period there was a decrease unrelated to intervention in the Blautia coccoides-Eubacterium rectale bacterial group levels and Clostridium cluster XIVab levels, but this decrease appeared to be halted during the synbiotic intervention. In conclusion, putatively beneficial changes in microbiota were observed in the elderly subjects supplemented with the synbiotic product. PMID:21853265

  19. Production of 13S-hydroxy-9(Z)-octadecenoic acid from linoleic acid by whole recombinant cells expressing linoleate 13-hydratase from Lactobacillus acidophilus.

    PubMed

    Park, Ji-Young; Lee, Seon-Hwa; Kim, Kyoung-Rok; Park, Jin-Byung; Oh, Deok-Kun

    2015-08-20

    Linoleate 13-hydratase from Lactobacillus acidophilus LMG 11470 converted linoleic acid to hydroxyl fatty acid, which was identified as 13S-hydroxy-9(Z)-octadecenoic acid (13-HOD) by GC-MS and NMR. The expression of linoleate 13-hydratase gene in Escherichia coli was maximized by using pACYC plasmid and super optimal broth with catabolite repression (SOC) medium containing 40mM Mg(2+). To optimize induction conditions, recombinant cells were cultivated at 37°C, 1mM isopropyl-β-d-thiogalactopyranoside was added at 2h, and the culture was further incubated at 16°C for 18h. Recombinant cells expressing linoleate 13-hydratase from L. acidophilus were obtained under the optimized expression conditions and used for 13-HOD production from linoleic acid. The optimal reaction conditions were pH 6.0, 40°C, 0.25% (v/v) Tween 40, 25gl(-1) cells, and 100gl(-1) linoleic acid, and under these conditions, whole recombinant cells produced 79gl(-1) 13-HOD for 3h with a conversion yield of 79% (w/w), a volumetric productivity of 26.3gl(-1)h(-1), and a specific productivity of 1.05g g-cells(-1)h(-1). To the best of our knowledge, the recombinant cells produced hydroxy fatty acid with the highest concentration and productivity reported so far. PMID:26015260

  20. Implications of modifying membrane fatty acid composition on membrane oxidation, integrity, and storage viability of freeze-dried probiotic, Lactobacillus acidophilus La-5.

    PubMed

    Hansen, Marie-Louise R W; Petersen, Mikael A; Risbo, Jens; Hümmer, Magdalena; Clausen, Anders

    2015-01-01

    The aim of this study was to investigate the effect of altering the fatty acid profile of the lipid membrane on storage survival of freeze-dried probiotic, Lactobacillus acidophilus La-5, as well as study the membrane integrity and lipid oxidation. The fatty acid composition of the lipid membrane of L. acidophilus La-5 was significantly different upon growth in MRS (containing Tween 80, an oleic acid source), or in MRS with Tween 20 (containing C12:0 and C14:0), linoleic, or linolenic acid supplemented. Bacteria grown in MRS showed the highest storage survival rates. No indications of loss of membrane integrity could be found, and membrane integrity could therefore not be connected with loss of viability. Survival of bacteria grown with linoleic or linolenic acid was more negatively affected by the presence of oxygen, than bacteria grown in MRS or with Tween 20 supplemented. A small, but significant, loss of linolenic acid during storage could be identified, and an increase of volatile secondary oxidation products during storage was found for bacteria grown in MRS, or with linoleic, or linolenic acid supplemented, but not for bacteria grown with Tween 20. Overall, the results indicate that lipid oxidation and loss of membrane integrity are not the only or most important detrimental reactions which can occur during storage. By altering the fatty acid composition, it was also found that properties of oleic acid gave rise to more robust bacteria than more saturated or unsaturated fatty acids did. PMID:25823709

  1. Lactobacillus acidophilus Increases the Anti-apoptotic Micro RNA-21 and Decreases the Pro-inflammatory Micro RNA-155 in the LPS-Treated Human Endothelial Cells.

    PubMed

    Kalani, Mehdi; Hodjati, Hossein; Sajedi Khanian, Mahdi; Doroudchi, Mehrnoosh

    2016-06-01

    Given the anti-inflammatory and protective role of probiotics in atherosclerosis and the regulatory role of micro RNA (miRNA) in endothelial cell (dys) functions, this study aimed to investigate the effect of Lactobacillus acidophilus (La) on cellular death and the expression of miRNA-21, 92a, 155, and 663 in human umbilical vein endothelial cell (HUVEC) induced by Escherichia coli lipopolysaccharide (Ec-LPS). LPS-treated and untreated HUVECs were cultured in the presence of different La conditions such as La-conditioned media (LaCM), La water extract (LaWE), La culture-filtered (LaFS) and unfiltered supernatants (LaUFS). After 24 h, apoptosis, necrosis and the levels of the mentioned miRNAs were measured using flow cytometry and real-time PCR methods, respectively. LaCM decreased apoptosis, necrosis and inflammatory miR-155 and conversely increased anti-apoptotic miR-21 in Ec-LPS-treated HUVECs. Association analysis revealed negative correlations between necrosis and the levels of miR-21, miR-92a, and miR-155. The beneficial effects of L. acidophilus on the ECs death and expression of atherosclerosis related miRNAs in these cells imply a new aspect of its regulation in cardiovascular diseases rather than previously described ones and suggest this probiotic bacterium as a candidate in the preventative therapy of atherosclerosis. PMID:27107761

  2. Probiotic properties of Lactobacillus strains isolated from the feces of breast-fed infants and Taiwanese pickled cabbage.

    PubMed

    Wang, Chung-Yi; Lin, Pei-Rong; Ng, Chang-Chai; Shyu, Yuan-Tay

    2010-12-01

    This study assessed potential probiotic Lactobacillus strains isolated from the feces of breast-fed infants and from Taiwanese pickled cabbage for their possible use in probiotic fermented foods by evaluating their (i) in vitro adhesive ability, resistance to biotic stress, resistance to pathogenic bacteria, and production of β-galactosidase; (ii) milk technological properties; and (iii) in vivo adhesive ability, intestinal survival and microbial changes during and after treatment. Five Lactobacillus isolates identified as Lactobacillus reuteri F03, Lactobacillus paracasei F08, Lactobacillus rhamnosus F14, Lactobacillus plantarum C06, and Lactobacillus acidophilus C11 that showed resistance to gastric juice and bile salts were selected for further evaluation of their probiotic properties. All the strains demonstrated the ability to adhere to Caco-2 cells, particularly, strain L. plantarum C06 and L. reuteri F03 showed satisfactory abilities, which were similar to that of the reference strain L. rhamnosus GG. The strains L. paracasei F08 and L. acidophilus C11 had the highest β-galactosidase activity. Most of the strains were resistant to aminoglycosides and vancomycin but sensitive to ampicillin, erythromycin, and penicillin. All the 5 strains elicited antibacterial activity against both Gram-positive (Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus) and -negative (Escherichia coli and Salmonella enterica) pathogens. Moreover, the strains L. reuteri F03, L. paracasei F08, and L. plantarum C06 could grow rapidly in milk without nutrient supplementation and reached 10⁸ cfu/mL after 24 h of fermentation at 37 °C. The viable cell counts of the 3 strains remained above 10⁷ cfu/mL after 21 d of storage at 4 °C. In the animal feeding trial, the number of intestinal lactobacilli increased significantly after administration of milk fermented with the 3 strains, and the counts of fecal coliforms and Clostridium perfringens were markedly reduced

  3. The In Vitro Antimicrobial Activities of Metabolites from Lactobacillus Strains on Candida Species Implicated in Candida Vaginitis

    PubMed Central

    Ogunshe, Adenike A O; Omotoso, Mopelola A; Bello, Victoria B

    2011-01-01

    Background: Research from developing countries, such as Nigeria, on Lactobacillus species in the female urogenital tract and their role as a barrier to vaginal infection is limited. Therefore, the aim of this study was to assess the clinical biotherapeutic potential of indigenous Lactobacillus species. Methods: Antimicrobial metabolites production were characterised using simple and easily reproducible qualitative and quantitative methods. The in vitro inhibitory effect of Lactobacillus antimicrobials on vulvovaginal candidiasis–associated Candida species was investigated using modified agar spot and agar well-diffusion methods. Results: The maximum levels of lactic acid, hydrogen peroxide, and diacetyl from 20 vaginal Lactobacillus strains from diseased subjects were 1.46 mg/L, 1.36 mmol/L, and 1.72 mg/L respectively. From the 4 healthy subjects, the maximum level of lactic acid was 1.08 mg/L; hydrogen peroxide, 1.36 mmol/L; and diacetyl, 0.86 mg/L. The maximum productions of these substances occurred between 72 and 120 hours of incubation. The in vitro antagonistic activities of vaginal L. acidophilus, L. fermentum, L. brevis, L. plantarum, L. casei, L. delbrueckii, and L. jensenii from diseased subjects inhibited a maximum of 5.71% of the 35 Candida species tested, while vaginal L. acidophilus and L. plantarum from healthy subjects inhibited between 57.1% and 68.6% of Candida species in vitro. Conclusion: Antimicrobial-producing lactobacilli can be considered as adjunct biotherapeutic candidates for the treatment of vulvovaginal candidiasis. PMID:22589669

  4. Caries arresting effect of silver diamine fluoride on dentine carious lesion with S. mutans and L. acidophilus dual-species cariogenic biofilm

    PubMed Central

    Mei, May L.; Low, Kan H.; Che, Ching M.; Lo, Edward CM.

    2013-01-01

    Objectives: This in vitro study investigated the effects of silver diamine fluoride (SDF) on dentine carious lesion with cariogenic biofilm. Study Design: Thirty human dentine blocks were inoculated with Streptococcus mutans and Lactobacillus acidophilus dual-species biofilm to create carious lesion. They were equally divided into test and control group to receive topical application of SDF and water. After incubation anaerobically using micro-well plate at 37oC for 7 days, the biofilms were evaluated for kinetics, morphology and viability by colony forming units (CFU), scanning electron microscopy (SEM), and confocal microscopy (CLSM), respectively. The carious lesion underwent crystal characteristics analysis, evaluation of the changes in chemical structure and density of collagen fibrils using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and immune-labeling. Results: The log CFU of S. mutans and L. acidophilus in the test group was significantly lower than control group. SEM and CLSM showed confluent biofilm in control group, but not in test group. XRD showed the loss of crystallinity of dentine due to the dissolution of hydroxyapatite crystal structure in test group was less than control group. FTIR showed that log [Amide I: HPO42-] for test vs. control group was 0.31±0.10 vs. 0.57±0.13 (p<0.05). The gold-labeling density in test vs. control group was 8.54±2.44/µm2 vs. 12.91±4.24/µm2 (p=0.04). Conclusions: SDF had antimicrobial activity against the cariogenic biofilms and reduced demineralization of dentine. Key words:Caries, caries arrest, dentine, silver, silver diamine fluoride, fluoride, biofilm,cariogenic. PMID:23722131

  5. Hip flexor strain - aftercare

    MedlinePlus

    Pulled hip flexor - aftercare; Hip flexor injury - aftercare; Hip flexor tear - aftercare; Iliopsoas strain - aftercare; Strained iliopsoas muscle - aftercare; Torn iliopsoas muscle - aftercare; Psoas strain - aftercare

  6. Systematic review and meta-analysis: Multi-strain probiotics as adjunct therapy for Helicobacter pylori eradication and prevention of adverse events

    PubMed Central

    Huang, Ying; Wang, Lin; Malfertheiner, Peter

    2015-01-01

    Background Eradication rates with triple therapy for Helicobacter pylori infections have currently declined to unacceptable levels worldwide. Newer quadruple therapies are burdened with a high rate of adverse events. Whether multi-strain probiotics can improve eradication rates or diminish adverse events remains uncertain. Methods Relevant publications in which patients with H. pylori infections were randomized to a multi-strain probiotic or control were identified in PubMed, Cochrane Databases, and other sources from 1 January 1960–3 June 2015. Primary outcomes included eradication rates, incidence of any adverse event and the incidence of antibiotic-associated diarrhea. As probiotic efficacy is strain-specific, pooled relative risks and 95% confidence intervals were calculated using meta-analysis stratified by similar multi-strain probiotic mixtures. Results A total of 19 randomized controlled trials (20 treatment arms, n = 2730) assessing one of six mixtures of strains of probiotics were included. Four multi-strain probiotics significantly improved H. pylori eradication rates, five significantly prevented any adverse reactions and three significantly reduced antibiotic-associated diarrhea. Only two probiotic mixtures (Lactobacillus acidophilus/Bifidobacterium animalis and an eight-strain mixture) had significant efficacy for all three outcomes. Conclusions Our meta-analysis found adjunctive use of some multi-strain probiotics may improve H. pylori eradication rates and prevent the development of adverse events and antibiotic-associated diarrhea, but not all mixtures were effective. PMID:27536365

  7. Comparative Analysis of the Effects of Two Probiotic Bacterial Strains on Metabolism and Innate Immunity in the RAW 264.7 Murine Macrophage Cell Line.

    PubMed

    Pradhan, Biswaranjan; Guha, Dipanjan; Ray, Pratikshya; Das, Debashmita; Aich, Palok

    2016-06-01

    Probiotic and potential probiotic bacterial strains are routinely prescribed and used as supplementary therapy for a variety infectious diseases, including enteric disorders among a wide range of individuals. While there are an increasing number of studies defining the possible mechanisms of probiotic activity, a great deal remains unknown regarding the diverse modes of action attributed to these therapeutic agents. More precise information is required to support the appropriate application of probiotics. To address this objective, we selected two probiotics strains, Lactobacillus acidophilus MTCC-10307 (LA) and Bacillus clausii MTCC-8326 (BC) that are frequently prescribed for the treatment of intestinal disorders and investigated their effects on the RAW 264.7 murine macrophage cell line. Our results reveal that LA and BC are potent activators of both metabolic activity and innate immune responses in these cells. We also observed that LA and BC possessed similar activity in preventing infection simulated in vitro in murine macrophages by Salmonella typhimurium serovar enterica. PMID:27038159

  8. High temperature strain gage apparent strain compensation

    NASA Technical Reports Server (NTRS)

    Holmes, Harlan K.; Moore, T. C., Sr.

    1992-01-01

    Once an installed strain gage is connected to a strain indicating device and the instrument is balanced, a subsequent change in temperature of the gage installation will generally produce a resistance change in the gage. This purely temperature-induced resistance will be registered by the indicating device as a strain and is referred to as 'apparent strain' to distinguish it from strain due to applied stress. One desirable technique for apparent strain compensation is to employ two identical gages with identical mounting procedures which are connected with a 'half bridge' configuration where gages see the same thermal environment but only one experiences a mechanical strain input. Their connection in adjacent arms of the bridge will then balance the thermally induced apparent strains and, in principle, only the mechanical strain remains. Two approaches that implement this technique are discussed.

  9. An oral preparation of Lactobacillus acidophilus for the treatment of uncomplicated acute watery diarrhoea in Vietnamese children: study protocol for a multicentre, randomised, placebo-controlled trial

    PubMed Central

    2013-01-01

    Background Diarrhoeal disease is a major global health problem, particularly affecting children under the age of 5 years. Besides oral rehydration solution, probiotics are also commonly prescribed to children with acute watery diarrhoea in some settings. Results from randomised clinical trials (RCTs) in which investigators studied the effect of probiotics on diarrhoeal symptoms have largely shown a positive effect; yet, the overall quality of the data is limited. In Vietnam, probiotics are the most frequently prescribed treatment for children hospitalised with acute watery diarrhoea, but there is little justification for this treatment in this location. We have designed a RCT to test the hypothesis that an oral preparation of Lactobacillus acidophilus is superior to placebo in the treatment of acute watery diarrhoea in Vietnamese children. Methods This RCT was designed to study the effect of treatment with L. acidophilus (4 × 109 colony-forming units/day) for 5 days for acute watery diarrhoea against a placebo in 300 children ages 9 to 60 months admitted to hospitals in Vietnam. Clinical and laboratory data plus samples will be collected on admission, daily during hospitalisation, at discharge, and at follow-up visits for a subset of participants. The primary end point will be defined as the time from the first dose of study medication to the start of the first 24-hour period without diarrhoea as assessed by the on-duty nurse. Secondary endpoints include the time to cessation of diarrhoea as recorded by parents or guardians in an hourly checklist, stool frequency over the first 3 days, treatment failure, rotavirus and norovirus viral loads, and adverse events. Discussion The existing evidence for the use of probiotics in treating acute watery diarrhoea seems to favour their use. However, the size of the effect varies across publications. An array of different probiotic organisms, doses, treatment durations, study populations, designs, settings, and aetiologies

  10. Geobacteraceae strains and methods

    DOEpatents

    Lovley, Derek R.; Nevin, Kelly P.; Yi, Hana

    2015-07-07

    Embodiments of the present invention provide a method of producing genetically modified strains of electricigenic microbes that are specifically adapted for the production of electrical current in microbial fuel cells, as well as strains produced by such methods and fuel cells using such strains. In preferred embodiments, the present invention provides genetically modified strains of Geobacter sulfurreducens and methods of using such strains.

  11. Effects of seven potential probiotic strains on specific immune responses in healthy adults: a double-blind, randomized, controlled trial.

    PubMed

    Paineau, Damien; Carcano, Didier; Leyer, Greg; Darquy, Sylviane; Alyanakian, Marie-Alexandra; Simoneau, Guy; Bergmann, Jean-François; Brassart, Dominique; Bornet, Francis; Ouwehand, Arthur C

    2008-06-01

    This pilot study investigated the immunomodulatory properties of seven probiotic strains. Eighty-three healthy volunteers aged 18-62 years consumed 2 x 10(10) CFU of bacteria or a placebo (maltodextrin) over 3 weeks (D0-D21). Subjects received an oral cholera vaccine at D7 and at D14; blood and saliva samples were collected at D0, D21 and D28. Serum samples were analyzed for specific IgA, IgG and IgM, and saliva samples were analyzed for specific IgA only, by ELISA. Statistical analyses were based on Wilcoxon's signed-rank test (intragroup analyses) and exact median t-test (intergroup analyses). Salivary analysis showed no difference in specific IgA concentrations between groups. Serum analysis indicated an effect of some of the tested strains on specific humoral responses. Between D0 and D21, IgG increased in two probiotic groups, for example, Bifidobacterium lactis Bl-04 and Lactobacillus acidophilus La-14, compared with controls (P=0.01). Trends toward significant changes in immunoglobulin serum concentrations compared with controls (P<0.1) were found for six out of the seven probiotic strains. In conclusion, some strains of probiotics demonstrated a faster immune response measured with serum immunoglobulin indicators, especially IgG, although overall vaccination was not influenced. Specific strains of probiotics may thus act as adjuvants to the humoral immune response following oral vaccination. PMID:18422632

  12. Sulfobacillus thermosulfidooxidans strain Cutipay enhances chalcopyrite bioleaching under moderate thermophilic conditions in the presence of chloride ion.

    PubMed

    Bobadilla-Fazzini, Roberto A; Cortés, Maria Paz; Maass, Alejandro; Parada, Pilar

    2014-12-01

    Currently more than 90% of the world's copper is obtained through sulfide mineral processing. Among the copper sulfides, chalcopyrite is the most abundant and therefore economically relevant. However, primary copper sulfide bioleaching is restricted due to high ionic strength raffinate solutions and particularly chloride coming from the dissolution of ores. In this work we describe the chalcopyrite bioleaching capacity of Sulfobacillus thermosulfidooxidans strain Cutipay (DSM 27601) previously described at the genomic level (Travisany et al. (2012) Draft genome sequence of the Sulfobacillus thermosulfidooxidans Cutipay strain, an indigenous bacterium isolated from a naturally extreme mining environment in Northern Chile. J Bacteriol 194:6327-6328). Bioleaching assays with the mixotrophic strain Cutipay showed a strong increase in copper recovery from chalcopyrite concentrate at 50°C in the presence of chloride ion, a relevant inhibitory element present in copper bioleaching processes. Compared to the abiotic control and a test with Sulfobacillus acidophilus DSM 10332, strain Cutipay showed an increase of 42 and 69% in copper recovery, respectively, demonstrating its high potential for chalcopyrite bioleaching. Moreover, a genomic comparison highlights the presence of the 2-Haloacid dehalogenase predicted-protein related to a potential new mechanism of chloride resistance in acidophiles. This novel and industrially applicable strain is under patent application CL 2013-03335. PMID:26267113

  13. Early administration of probiotic Lactobacillus acidophilus and/or prebiotic inulin attenuates pathogen-mediated intestinal inflammation and Smad 7 cell signaling

    PubMed Central

    Foye, Ondulla T.; Huang, I-Fei; Chiou, Christine C.; Walker, W. Allan; Shi, Hai Ning

    2014-01-01

    Immaturity of gut-associated immunity may contribute to pediatric mortality associated with enteric infections. A murine model to parallel infantile enteric disease was used to determine the effects of probiotic, Lactobacillus acidophilus (La), prebiotic, inulin, or both (synbiotic, syn) on pathogen-induced inflammatory responses, NF-κB, and Smad 7 signaling. Newborn mice were inoculated bi-weekly for 4 weeks with La, inulin, or syn and challenged with Citrobacter rodentium (Cr) at 5 weeks. Mouse intestinal epithelial cells (CMT93) were exposed to Cr to determine temporal alterations in NF-Kappa B and Smad 7 levels. Mice with pretreatment of La, inulin, and syn show reduced intestinal inflammation following Cr infection compared with controls, which is associated with significantly reduced bacterial colonization in La, inulin, and syn animals. Our results further show that host defense against Cr infection correlated with enhanced colonic IL-10 and transforming growth factor-β expression and inhibition of NF-κB in syn-treated mice, whereas mice pretreated with syn, La, or inulin had attenuation of Cr-induced Smad 7 expression. There was a temporal Smad 7 and NF-κB intracellular accumulation post-Cr infection and post-tumor necrosis factor stimulation in CMT93 cells. These results, therefore, suggest that probiotic, La, prebiotic inulin, or synbiotic may promote host-protective immunity and attenuate Cr-induced intestinal inflammation through mechanisms affecting NF-κB and Smad 7 signaling. PMID:22524476

  14. In vitro fermentation of rice bran combined with Lactobacillus acidophilus 14 150B or Bifidobacterium longum 05 by the canine faecal microbiota.

    PubMed

    Ogué-Bon, Eva; Khoo, Christina; Hoyles, Lesley; McCartney, Anne L; Gibson, Glenn R; Rastall, Robert A

    2011-03-01

    The fermentability of rice bran (RB), alone or in combination with one of two probiotics, by canine faecal microbiota was evaluated in stirred, pH-controlled, anaerobic batch cultures. RB enhanced the levels of bacteria detected by probes Bif164 (bifidobacteria) and Lab158 (lactic acid bacteria); however, addition of the probiotics did not have a significant effect on the predominant microbial counts compared with RB alone. RB sustained levels of Bifidobacterium longum 05 throughout the fermentation; in contrast, Lactobacillus acidophilus 14 150B levels decreased significantly after 5-h fermentation. RB fermentation induced changes in the short-chain fatty acid (SCFA) profile. However, RB combined with probiotics did not alter the SCFA levels compared with RB alone. Denaturing gradient gel electrophoresis analysis of samples obtained at 24 h showed a treatment effect with RB, which was not observed in the RB plus probiotic systems. Overall, the negative controls displayed lower species richness than the treatment systems and their banding profiles were distinct. This study illustrates the ability of a common ingredient found in pet food to modulate the canine faecal microbiota and highlights that RB may be an economical alternative to prebiotics for use in dog food. PMID:21204868

  15. Efficient one-pot enzymatic synthesis of alpha-(1-->4)-glucosidic disaccharides through a coupled reaction catalysed by Lactobacillus acidophilus NCFM maltose phosphorylase.

    PubMed

    Nakai, Hiroyuki; Dilokpimol, Adiphol; Abou Hachem, Maher; Svensson, Birte

    2010-05-27

    Lactobacillus acidophilus NCFM maltose phosphorylase (LaMalP) of glycoside hydrolase family 65 catalysed enzymatic synthesis of alpha-(1-->4)-glucosidic disaccharides from maltose and five monosaccharides in a coupled phosphorolysis/reverse phosphorolysis one-pot reaction. Thus phosphorolysis of maltose to beta-glucose 1-phosphate circumvented addition of costly beta-glucose 1-phosphate for reverse phosphorolysis with different monosaccharide acceptors, resulting in 91%, 89%, 88%, 86% and 84% yield of alpha-d-glucopyranosyl-(1-->4)-N-acetyl-D-glucosaminopyranose [N-acetyl-maltosamine], alpha-D-glucopyranosyl-(1-->4)-D-glucosaminopyranose [maltosamine], alpha-D-glucopyranosyl-(1-->4)-D-mannopyranose, alpha-D-glucopyranosyl-(1-->4)-L-fucopyranose and alpha-D-glucopyranosyl-(1-->4)-D-xylopyranose, respectively, from 0.1M maltose, 0.5M N-acetyl glucosamine, 0.1M glucosamine, 0.1M mannose, 1M L-fucose and 0.5M xylose in 0.2M phosphate-citrate pH 6.2. These current yields of 0.27-0.34 g of disaccharide products from 10 mL reaction mixtures are easy to scale up and moreover the strategy can be applied to large-scale production of other oligosaccharides from low-cost disaccharides as catalysed by phosphorylases with different substrate specificities. PMID:20392438

  16. The Differential Proteome of the Probiotic Lactobacillus acidophilus NCFM Grown on the Potential Prebiotic Cellobiose Shows Upregulation of Two β-Glycoside Hydrolases

    PubMed Central

    van Zanten, Gabriella C.; Sparding, Nadja; Majumder, Avishek; Lahtinen, Sampo J.; Svensson, Birte; Jacobsen, Susanne

    2015-01-01

    Probiotics, prebiotics, and combinations thereof, that is, synbiotics, are known to exert beneficial health effects in humans; however interactions between pro- and prebiotics remain poorly understood at the molecular level. The present study describes changes in abundance of different proteins of the probiotic bacterium Lactobacillus acidophilus NCFM (NCFM) when grown on the potential prebiotic cellobiose as compared to glucose. Cytosolic cell extract proteomes after harvest at late exponential phase of NCFM grown on cellobiose or glucose were analyzed by two dimensional difference gel electrophoresis (2D-DIGE) in the acidic (pH 4–7) and the alkaline (pH 6–11) regions showing a total of 136 spots to change in abundance. Proteins were identified by MS or MS/MS from 81 of these spots representing 49 unique proteins and either increasing 1.5–13.9-fold or decreasing 1.5–7.8-fold in relative abundance. Many of these proteins were associated with energy metabolism, including the cellobiose related glycoside hydrolases phospho-β-glucosidase (LBA0881) and phospho-β-galactosidase II (LBA0726). The data provide insight into the utilization of the candidate prebiotic cellobiose by the probiotic bacterium NCFM. Several of the upregulated or downregulated identified proteins associated with utilization of cellobiose indicate the presence of carbon catabolite repression and regulation of enzymes involved in carbohydrate metabolism. PMID:25961012

  17. The Differential Proteome of the Probiotic Lactobacillus acidophilus NCFM Grown on the Potential Prebiotic Cellobiose Shows Upregulation of Two β -Glycoside Hydrolases.

    PubMed

    van Zanten, Gabriella C; Sparding, Nadja; Majumder, Avishek; Lahtinen, Sampo J; Svensson, Birte; Jacobsen, Susanne

    2015-01-01

    Probiotics, prebiotics, and combinations thereof, that is, synbiotics, are known to exert beneficial health effects in humans; however interactions between pro- and prebiotics remain poorly understood at the molecular level. The present study describes changes in abundance of different proteins of the probiotic bacterium Lactobacillus acidophilus NCFM (NCFM) when grown on the potential prebiotic cellobiose as compared to glucose. Cytosolic cell extract proteomes after harvest at late exponential phase of NCFM grown on cellobiose or glucose were analyzed by two dimensional difference gel electrophoresis (2D-DIGE) in the acidic (pH 4-7) and the alkaline (pH 6-11) regions showing a total of 136 spots to change in abundance. Proteins were identified by MS or MS/MS from 81 of these spots representing 49 unique proteins and either increasing 1.5-13.9-fold or decreasing 1.5-7.8-fold in relative abundance. Many of these proteins were associated with energy metabolism, including the cellobiose related glycoside hydrolases phospho-β-glucosidase (LBA0881) and phospho-β-galactosidase II (LBA0726). The data provide insight into the utilization of the candidate prebiotic cellobiose by the probiotic bacterium NCFM. Several of the upregulated or downregulated identified proteins associated with utilization of cellobiose indicate the presence of carbon catabolite repression and regulation of enzymes involved in carbohydrate metabolism. PMID:25961012

  18. The Lactobacillus acidophilus S-layer protein gene expression site comprises two consensus promoter sequences, one of which directs transcription of stable mRNA.

    PubMed Central

    Boot, H J; Kolen, C P; Andreadaki, F J; Leer, R J; Pouwels, P H

    1996-01-01

    S-proteins are proteins which form a regular structure (S-layer) on the outside of the cell walls of many bacteria. Two S-protein-encoding genes are located in opposite directions on a 6.0-kb segment of the chromosome of Lactobacillus acidophilus ATCC 4356 bacteria. Inversion of this chromosomal segment occurs through recombination between two regions with identical sequences, thereby interchanging the expressed and the silent genes. In this study, we show that the region involved in recombination also has a function in efficient S-protein production. Two promoter sequences are present in the S-protein gene expression site, although only the most downstream promoter (P-1) is used to direct mRNA synthesis. S-protein mRNA directed by this promoter has a half-life of 15 min. Its untranslated leader can form a stable secondary structure in which the 5' end is base paired, whereas the ribosome-binding site is exposed. Truncation of this leader sequence results in a reduction in protein production, as shown by reporter gene analysis of Lactobacillus casei. The results obtained indicate that the untranslated leader sequence of S-protein mRNA is involved in efficient S-protein production. PMID:8808926

  19. Early administration of probiotic Lactobacillus acidophilus and/or prebiotic inulin attenuates pathogen-mediated intestinal inflammation and Smad 7 cell signaling.

    PubMed

    Foye, Ondulla T; Huang, I-Fei; Chiou, Christine C; Walker, W Allan; Shi, Hai Ning

    2012-08-01

    Immaturity of gut-associated immunity may contribute to pediatric mortality associated with enteric infections. A murine model to parallel infantile enteric disease was used to determine the effects of probiotic, Lactobacillus acidophilus (La), prebiotic, inulin, or both (synbiotic, syn) on pathogen-induced inflammatory responses, NF-κB, and Smad 7 signaling. Newborn mice were inoculated bi-weekly for 4 weeks with La, inulin, or syn and challenged with Citrobacter rodentium (Cr) at 5 weeks. Mouse intestinal epithelial cells (CMT93) were exposed to Cr to determine temporal alterations in NF-Kappa B and Smad 7 levels. Mice with pretreatment of La, inulin, and syn show reduced intestinal inflammation following Cr infection compared with controls, which is associated with significantly reduced bacterial colonization in La, inulin, and syn animals. Our results further show that host defense against Cr infection correlated with enhanced colonic IL-10 and transforming growth factor-β expression and inhibition of NF-κB in syn-treated mice, whereas mice pretreated with syn, La, or inulin had attenuation of Cr-induced Smad 7 expression. There was a temporal Smad 7 and NF-κB intracellular accumulation post-Cr infection and post-tumor necrosis factor stimulation in CMT93 cells. These results, therefore, suggest that probiotic, La, prebiotic inulin, or synbiotic may promote host-protective immunity and attenuate Cr-induced intestinal inflammation through mechanisms affecting NF-κB and Smad 7 signaling. PMID:22524476

  20. Strains and Sprains

    MedlinePlus

    ... Children's Sports Injuries Computer-Related Repetitive Stress Injuries Knee Injuries Broken Bones, Sprains, and Strains Strains and Sprains ... Pain Going to a Physical Therapist Hamstring Strain Knee Injuries Sports and Exercise Safety Dealing With Sports Injuries ...

  1. Muscle strain (image)

    MedlinePlus

    A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a ... something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the ...

  2. Muscle strain treatment

    MedlinePlus

    Treatment - muscle strain ... Question: How do you treat a muscle strain ? Answer: Rest the strained muscle and apply ice for the first few days after the injury. Anti-inflammatory medicines or acetaminophen ( ...

  3. Program Calibrates Strain Gauges

    NASA Technical Reports Server (NTRS)

    Okazaki, Gary D.

    1991-01-01

    Program dramatically reduces personnel and time requirements for acceptance tests of hardware. Data-acquisition system reads output from Wheatstone full-bridge strain-gauge circuit and calculates strain by use of shunt calibration technique. Program nearly instantaneously tabulates and plots strain data against load-cell outputs. Modified to acquire strain data for other specimens wherever full-bridge strain-gauge circuits used. Written in HP BASIC.

  4. Superlattice strain gage

    DOEpatents

    Noel, Bruce W.; Smith, Darryl L.; Sinha, Dipen N.

    1990-01-01

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element.

  5. Superlattice strain gage

    DOEpatents

    Noel, B.W.; Smith, D.L.; Sinha, D.N.

    1988-06-28

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element. 8 figs.

  6. Quantitative profiling of bacteriocins present in dairy-free probiotic preparations of Lactobacillus acidophilus by nanoliquid chromatography-tandem mass spectrometry.

    PubMed

    Nandakumar, Renu; Talapatra, Kesh

    2014-01-01

    Bacteriocins are a heterogeneous group of ribosomally synthesized peptides or proteins with antimicrobial activity, produced predominantly by lactic acid bacteria, with potential applications as biopreservatives and probiotics. We describe here a novel strategy based on a bottom-up, shotgun proteomic approach using nanoliquid chromatography-tandem mass spectrometry (nanoLC-MS/MS) with multiple fragmentation techniques for the quantitative profiling of bacteriocins present in the probiotic preparations of Lactobacillus acidophilus. A direct LC-MS/MS analysis with alternate collision-induced dissociation, high-energy collision dissociation, and electron-transfer dissociation fragmentation following a filter-assisted size-exclusion sample prefractionation has resulted in the identification of peptides belonging to 37 bacteriocins or related proteins. Peptides from lactacin F, helveticin J, lysin, avicin A, acidocin M, curvaticin FS47, and carocin D were predominant. The process of freeze drying under vacuum was observed to affect both the diversity and abundance of bacteriocins. Data acquisition using alternating complementary peptide fragmentation modes, especially electron-transfer dissociation, has significantly enhanced the peptide sequence coverage and number of bacteriocin peptides identified. Multi-enzyme proteolytic digestion was observed to increase the sample complexity and dynamic range, lowering the chances of detection of low-abundant bacteriocin peptides by LC-MS/MS. An analytical platform integrating size exclusion prefractionation, nanoLC-MS/MS analysis with multiple fragmentation techniques, and data-dependent decision tree-driven bioinformatic data analysis is novel in bacteriocin research and suitable for the comprehensive bioanalysis of diverse, low-abundant bacteriocins in complex samples. PMID:24565320

  7. Lactobacillus acidophilus stimulates intestinal P-glycoprotein expression via a c-Fos/c-Jun-dependent mechanism in intestinal epithelial cells.

    PubMed

    Priyamvada, Shubha; Anbazhagan, Arivarasu N; Kumar, Anoop; Soni, Vikas; Alrefai, Waddah A; Gill, Ravinder K; Dudeja, Pradeep K; Saksena, Seema

    2016-04-15

    Our previous studies showed that Lactobacillus acidophilus (LA) culture supernatant (CS) increased P-glycoprotein [Pgp/multidrug resistance 1 (MDR1)] function, expression, and promoter activity in Caco-2 cells. The current studies were designed to elucidate the molecular mechanisms mediating the stimulatory effects of LA CS on Pgp promoter activity. Deletion analysis indicated that the LA CS response element(s) is located in the -172/+428-bp region, and sequence analysis of this region revealed three potential binding sites for c-Fos or c-Jun: proximal activating protein (AP) 1a (-119/-98 bp), distal AP1b (-99/-78 bp), and AP1c (+175/+196 bp). LA CS (24 h) showed an approximately twofold increase in the protein expression of c-Fos and c-Jun in Caco-2 cells. Electrophoretic mobility shift assay showed that LA CS markedly increased the binding of Caco-2 nuclear proteins to AP1a and AP1b, but not AP1c. The DNA-protein complex was completely eliminated by c-Fos antibody, while c-Jun antibody partially eliminated the complex. Chromatin immunoprecipitation analysis also showed that LA CS enhanced the association of c-Fos and c-Jun (by ∼4- and 1.5-fold, respectively) with endogenous Pgp promoter in Caco-2 cells (p-172/+1). Interestingly, overexpression of c-Fos or c-Jun activated Pgp promoter by nearly twofold each. This increase was further enhanced (∼14-fold) when c-Fos and c-Jun were simultaneously overexpressed, suggesting that the presence of one of these transcription factors potentiates the effect of the other. These studies, for the first time, provide evidence for the involvement of c-Fos/c-Jun in stimulation of Pgp gene expression by LA CS in the human intestine. PMID:26867563

  8. Fructooligosaccharides and Lactobacillus acidophilus modify gut microbial populations, total tract nutrient digestibilities and fecal protein catabolite concentrations in healthy adult dogs.

    PubMed

    Swanson, Kelly S; Grieshop, Christine M; Flickinger, Elizabeth A; Bauer, Laura L; Chow, JoMay; Wolf, Bryan W; Garleb, Keith A; Fahey, George C

    2002-12-01

    The objective of this research was to determine whether fructooligosaccharides (FOS) and (or) Lactobacillus acidophilus (LAC) affected concentrations of gut microbial populations, fermentative end products and nutrient digestibilities in healthy adult dogs. Two experiments were performed using 40 adult dogs (20 dogs/experiment). Dogs in each experiment were randomly assigned to one of 4 treatments. Twice daily, treatments were given orally via gelatin capsules: 1) 2 g sucrose + 80 mg cellulose; 2) 2 g FOS + 80 mg cellulose; 3) 2 g sucrose + 1 x 10(9) colony forming units (cfu) LAC; or 4) 2 g FOS + 1 x 10(9) cfu LAC. Data were analyzed by the General Linear Models procedure of SAS. In Experiment 1, FOS resulted in lower (P = 0.08) Clostridium perfringens and greater fecal butyrate (P = 0.06) and lactate (P < 0.05) concentrations. In Experiment 2, FOS supplementation increased (P < 0.05) bifidobacteria, increased lactobacilli (P = 0.08), increased fecal lactate (P = 0.06) and butyrate (P < 0.05), and decreased (P < 0.05) fecal ammonia, isobutyrate, isovalerate and total branched-chain fatty acid concentrations. Dogs fed LAC had the highest fecal concentrations of hydrogen sulfide and methanethiol in Experiment 1 and dimethyl sulfide in Experiment 2, whereas dogs fed FOS had the lowest concentrations of these compounds. Overall, FOS appeared to enhance indices of gut health by positively altering gut microbial ecology and fecal protein catabolites, whereas LAC was more effective when fed in combination with FOS rather than fed alone. PMID:12468613

  9. Oral inoculation of probiotics Lactobacillus acidophilus NCFM suppresses tumour growth both in segmental orthotopic colon cancer and extra-intestinal tissue.

    PubMed

    Chen, Chien-Chang; Lin, Wei-Chuan; Kong, Man-Shan; Shi, Hai Ning; Walker, W Allan; Lin, Chun-Yen; Huang, Ching-Tai; Lin, Yung-Chang; Jung, Shih-Ming; Lin, Tzou-Yien

    2012-06-01

    Modulation of the cellular response by the administration of probiotic bacteria may be an effective strategy for preventing or inhibiting tumour growth. We orally pre-inoculated mice with probiotics Lactobacillus acidophilus NCFM (La) for 14 d. Subcutaneous dorsal-flank tumours and segmental orthotopic colon cancers were implanted into mice using CT-26 murine colon adenocarcinoma cells. On day 28 after tumour initiation, the lamina propria of the colon, mesenteric lymph nodes (MLN) and spleen were harvested and purified for flow cytometry and mRNA analyses. We demonstrated that La pre-inoculation reduced tumour volume growth by 50·3 %, compared with untreated mice at 28 d after tumour implants (2465·5 (SEM 1290·4) v. 4950·9 (SEM 1689·3) mm³, P<0·001). Inoculation with La reduced the severity of colonic carcinogenesis caused by CT-26 cells, such as level of colonic involvement and structural abnormality of epithelial/crypt damage. Moreover, La enhanced apoptosis of CT-26 cells both in dorsal-flank tumour and segmental orthotopic colon cancer, and the mean counts of apoptotic body were higher in mice pre-inoculated with La (P<0·05) compared with untreated mice. La pre-inoculation down-regulated the CXCR4 mRNA expressions in the colon, MLN and extra-intestinal tissue, compared with untreated mice (P<0·05). In addition, La pre-inoculation reduced the mean fluorescence index of MHC class I (H-2Dd, -Kd and -Ld) in flow cytometry analysis. Taken together, these findings suggest that probiotics La may play a role in attenuating tumour growth during CT-26 cell carcinogenesis. The down-regulated expression of CXCR4 mRNA and MHC class I, as well as increasing apoptosis in tumour tissue, indicated that La may be associated with modulating the cellular response triggered by colon carcinogenesis. PMID:21992995

  10. Impact of two probiotic Lactobacillus strains feeding on fecal lactobacilli and weight gains in chicken.

    PubMed

    Lan, Pham Thi Ngoc; Binh, Le Thanh; Benno, Yoshimi

    2003-02-01

    Two probiotic strains, Lactobacillus agilis JCM 1048 and L. salivarius subsp. salicinius JCM 1230 isolated from chicken intestine, exhibited probiotic characteristics that can be applied for chicken production. After 7 days of probiotic feeding (FD7), the count of intestinal lactobacilli in the probiotic group (group P, n=10) was significantly (p<0.05) higher than that in the control group (group C, n=9). After 40 days of probiotic feeding (FD40), the lactobacilli and enterococci counts were stable but the Enterobacteriaceae number was significantly reduced (p<0.05). A total of 163 isolated lactobacilli were identified as the L. acidophilus/gallinarum group (49.7%), L. agilis (30.7%), L. salivarius (9.2%), L. reuteri (9.2%), and Lactobacillus spp. (1.2%). The probiotic lactobacilli positively affected the Lactobacillus biota in chickens at FD7, with a significant increase in the number (p<0.05) of L. agilis and group P. The viable counts of each Lactobacillus species at FD40, however, showed no differences between two groups. An increasing incidence of L. agilis was also noted with probiotic feeding. The probiotic effect of two strains resulted in significantly increased weight gains (10.7%) of group P in comparison with group C at FD40 (p<0.01). PMID:12682864

  11. Miniature biaxial strain transducer

    NASA Technical Reports Server (NTRS)

    Hoffman, I. S. (Inventor)

    1976-01-01

    A reusable miniature strain transducer for use in the measurement of static or quasi-static, high level, biaxial strain on the surface of test specimens or structures was studied. Two cantilever arms, constructed by machining the material to appropriate flexibility, are self-aligning and constitute the transducing elements of the device. Used in conjunction with strain gages, the device enables testing beyond normal gage limits for high strains and number of load cycles. The device does not require conversion computations since the electrical output of the strain gages is directly proportional to the strain measured.

  12. The inhibitory effect of a fermented papaya preparation on growth, hydrophobicity, and acid production of Streptococcus mutans, Streptococcus mitis, and Lactobacillus acidophilus: its implications in oral health improvement of diabetics

    PubMed Central

    Somanah, Jhoti; Bourdon, Emmanuel; Bahorun, Theeshan; Aruoma, Okezie I

    2013-01-01

    Fermented papaya preparation (FPP) is a “natural health product.” The high incidence of dental caries, gingivitis, periodontitis, and oral microbial infection cases among patients with diabetes mellitus continues to prevail. The potential role of FPP against common oral microbiota (Streptococcus mutans, Streptococcus mitis, and Lactobacillus acidophilus) isolated from the human oral cavity was investigated using in vitro simulation models of dental plaque and caries. FPP showed an inhibitory effect against the growth (at 0.05 mg/mL: S. mutans: −6.9%; S. mitis: −4.47%, P < 0.05), acid production (at 0.05 mg/mL: S. mutans: +6.38%; L. acidophilus: +2.25%), and hydrophobicity (at 50 mg/mL: S. mutans: 1.01%, P < 0.01; S. mitis: 7.66%, P < 0.05) of tested microbiota. The results of this study suggest that low doses of FPP may be a suitable complement to good oral hygiene practice for the effective prevention of dental caries, plaque, and gingivitis. The functional application of FPP as a constituent of a balanced diet and active lifestyle can make a positive contribution to the oral health status and well-being of patients with diabetes. PMID:24804050

  13. AI-2 signalling is induced by acidic shock in probiotic strains of Lactobacillus spp.

    PubMed

    Moslehi-Jenabian, Saloomeh; Gori, Klaus; Jespersen, Lene

    2009-11-15

    Survival and ability to respond to various environmental stresses such as low pH are important factors for lactobacilli for their function as probiotics. LuxS-mediated quorum sensing mechanism, which is based on the production of universal signal molecule called autoinducer-2 (AI-2), regulates important physiological traits and a variety of adaptive processes in different bacteria. The aim of this study was to investigate the effect of acidic stress on LuxS-mediated quorum sensing (AI-2 signalling) in four probiotic strains of different Lactobacillus species. Initially, the production of AI-2-like molecule was investigated in four strains of Lactobacillus spp. at standard growth conditions using Vibrio harveyi bioluminescence assay. Species variation in AI-2 activity was observed. AI-2 activity started at early-exponential growth phase and increased during the mid-exponential phase concomitant with the reduction of pH, reaching maximum at late exponential phase (L. rhamnosus GG) or at stationary phase (L. salivarius UCC118, L. acidophilus NCFM and L. johnsonii NCC533). Acidic shock experiments were conducted on L. rhamnosus GG and L. acidophilus NCFM after exposure to different acidic shocks (pH 5.0, 4.0 and 3.0) and to pH 6.5 as control, measuring AI-2 activity and transcription of the luxS gene. AI-2 activity increased by lowering the pH in a dose dependent manner and was negatively influenced by acid adaptation. In both species, the luxS gene was repressed after exposure to pH 6.5 as control. However, after acidic shock (pH 4.0) a transient response of luxS gene was observed and the transcription augmented over time, reaching a maximum level and decreased subsequently. Acid adaptation of cells attenuated the transcription of this gene. Based on the observations done in the present study, the luxS gene appears to have a clear role in acidic stress response in probiotic lactobacilli. This might be important in the survival of these bacteria during the passage

  14. Strains and Sprains

    MedlinePlus

    ... move the injured part, and you might even think you have broken a bone. How Does a Strain or Sprain Happen? Strains often happen when you put a lot of pressure on a muscle or you push it too far, such as when lifting a heavy object. Strains may be more likely to happen if ...

  15. Sprains and Strains

    MedlinePlus

    ... happens. A strain is a stretched or torn muscle or tendon. Tendons are tissues that connect muscle to bone. Twisting or pulling these tissues can ... suddenly or develop over time. Back and hamstring muscle strains are common. Many people get strains playing ...

  16. The maltodextrin transport system and metabolism in Lactobacillus acidophilus NCFM and production of novel alpha-glucosides through reverse phosphorolysis by maltose phosphorylase.

    PubMed

    Nakai, Hiroyuki; Baumann, Martin J; Petersen, Bent O; Westphal, Yvonne; Schols, Henk; Dilokpimol, Adiphol; Hachem, Maher A; Lahtinen, Sampo J; Duus, Jens Ø; Svensson, Birte

    2009-12-01

    A gene cluster involved in maltodextrin transport and metabolism was identified in the genome of Lactobacillus acidophilus NCFM, which encoded a maltodextrin-binding protein, three maltodextrin ATP-binding cassette transporters and five glycosidases, all under the control of a transcriptional regulator of the LacI-GalR family. Enzymatic properties are described for recombinant maltose phosphorylase (MalP) of glycoside hydrolase family 65 (GH65), which is encoded by malP (GenBank: AAV43670.1) of this gene cluster and produced in Escherichia coli. MalP catalyses phosphorolysis of maltose with inversion of the anomeric configuration releasing beta-glucose 1-phosphate (beta-Glc 1-P) and glucose. The broad specificity of the aglycone binding site was demonstrated by products formed in reverse phosphorolysis using various carbohydrate acceptor substrates and beta-Glc 1-P as the donor. MalP showed strong preference for monosaccharide acceptors with equatorial 3-OH and 4-OH, such as glucose and mannose, and also reacted with 2-deoxy glucosamine and 2-deoxy N-acetyl glucosamine. By contrast, none of the tested di- and trisaccharides served as acceptors. Disaccharide yields obtained from 50 mmbeta-Glc 1-P and 50 mm glucose, glucosamine, N-acetyl glucosamine, mannose, xylose or l-fucose were 99, 80, 53, 93, 81 and 13%, respectively. Product structures were determined by NMR and ESI-MS to be alpha-Glcp-(1-->4)-Glcp (maltose), alpha-Glcp-(1-->4)-GlcNp (maltosamine), alpha-Glcp-(1-->4)-GlcNAcp (N-acetyl maltosamine), alpha-Glcp-(1-->4)-Manp, alpha-Glcp-(1-->4)-Xylp and alpha-Glcp-(1-->4)- L-Fucp, the three latter being novel compounds. Modelling using L. brevis GH65 as the template and superimposition of acarbose from a complex with Thermoanaerobacterium thermosaccharolyticum GH15 glucoamylase suggested that loop 3 of MalP involved in substrate recognition blocked the binding of candidate acceptors larger than monosaccharides. PMID:19919544

  17. Anti-infective activities of lactobacillus strains in the human intestinal microbiota: from probiotics to gastrointestinal anti-infectious biotherapeutic agents.

    PubMed

    Liévin-Le Moal, Vanessa; Servin, Alain L

    2014-04-01

    A vast and diverse array of microbial species displaying great phylogenic, genomic, and metabolic diversity have colonized the gastrointestinal tract. Resident microbes play a beneficial role by regulating the intestinal immune system, stimulating the maturation of host tissues, and playing a variety of roles in nutrition and in host resistance to gastric and enteric bacterial pathogens. The mechanisms by which the resident microbial species combat gastrointestinal pathogens are complex and include competitive metabolic interactions and the production of antimicrobial molecules. The human intestinal microbiota is a source from which Lactobacillus probiotic strains have often been isolated. Only six probiotic Lactobacillus strains isolated from human intestinal microbiota, i.e., L. rhamnosus GG, L. casei Shirota YIT9029, L. casei DN-114 001, L. johnsonii NCC 533, L. acidophilus LB, and L. reuteri DSM 17938, have been well characterized with regard to their potential antimicrobial effects against the major gastric and enteric bacterial pathogens and rotavirus. In this review, we describe the current knowledge concerning the experimental antibacterial activities, including antibiotic-like and cell-regulating activities, and therapeutic effects demonstrated in well-conducted, placebo-controlled, randomized clinical trials of these probiotic Lactobacillus strains. What is known about the antimicrobial activities supported by the molecules secreted by such probiotic Lactobacillus strains suggests that they constitute a promising new source for the development of innovative anti-infectious agents that act luminally and intracellularly in the gastrointestinal tract. PMID:24696432

  18. Anti-Infective Activities of Lactobacillus Strains in the Human Intestinal Microbiota: from Probiotics to Gastrointestinal Anti-Infectious Biotherapeutic Agents

    PubMed Central

    Liévin-Le Moal, Vanessa

    2014-01-01

    SUMMARY A vast and diverse array of microbial species displaying great phylogenic, genomic, and metabolic diversity have colonized the gastrointestinal tract. Resident microbes play a beneficial role by regulating the intestinal immune system, stimulating the maturation of host tissues, and playing a variety of roles in nutrition and in host resistance to gastric and enteric bacterial pathogens. The mechanisms by which the resident microbial species combat gastrointestinal pathogens are complex and include competitive metabolic interactions and the production of antimicrobial molecules. The human intestinal microbiota is a source from which Lactobacillus probiotic strains have often been isolated. Only six probiotic Lactobacillus strains isolated from human intestinal microbiota, i.e., L. rhamnosus GG, L. casei Shirota YIT9029, L. casei DN-114 001, L. johnsonii NCC 533, L. acidophilus LB, and L. reuteri DSM 17938, have been well characterized with regard to their potential antimicrobial effects against the major gastric and enteric bacterial pathogens and rotavirus. In this review, we describe the current knowledge concerning the experimental antibacterial activities, including antibiotic-like and cell-regulating activities, and therapeutic effects demonstrated in well-conducted, placebo-controlled, randomized clinical trials of these probiotic Lactobacillus strains. What is known about the antimicrobial activities supported by the molecules secreted by such probiotic Lactobacillus strains suggests that they constitute a promising new source for the development of innovative anti-infectious agents that act luminally and intracellularly in the gastrointestinal tract. PMID:24696432

  19. Elevated temperature strain gages

    NASA Technical Reports Server (NTRS)

    Brittain, J. O.; Geslin, D.; Lei, J. F.

    1986-01-01

    One of the goals of the HOST Program is the development of electrical resistance strain gages for static strain measurements at temperatures equal to or greater than 1273 K. Strain gage materials must have a reproducible or predictable response to temperature, time and strain. It is the objective of this research to investigate criteria for the selection of materials for such applications through electrical properties studies. The results of the investigation of two groups of materials, refractory compounds and binary alloy solid solutions are presented.

  20. Thin film strain transducer

    NASA Technical Reports Server (NTRS)

    Rand, J. L. (Inventor)

    1984-01-01

    A strain transducer system and process for making the same is disclosed. A beryllium copper ring having four strain gages is electrically connected in Wheatstone bridge fashion to the output instrumentation. Tabs are bonded to a balloon or like surface with strain on the surface causing bending of a ring which provides an electrical signal through the gages proportional to the surface strain. A photographic pattern of a one half ring segment as placed on a sheet of beryllium copper for chem-mill etch formation is illustrated.

  1. Can strain magnetize light?

    NASA Astrophysics Data System (ADS)

    2013-02-01

    Strain in photonic structures can induce pseudomagnetic fields and Landau levels. Nature Photonics spoke to Mordechai Segev, Mikael Rechtsman, Alexander Szameit and Julia Zeuner about their unique approach.

  2. Geodetic Strain Analysis Tool

    NASA Technical Reports Server (NTRS)

    Kedar, Sharon; Baxter, Sean C.; Parker, Jay W.; Webb, Frank H.; Owen, Susan E.; Sibthorpe, Anthony J.; Dong, Danan

    2011-01-01

    A geodetic software analysis tool enables the user to analyze 2D crustal strain from geodetic ground motion, and create models of crustal deformation using a graphical interface. Users can use any geodetic measurements of ground motion and derive the 2D crustal strain interactively. This software also provides a forward-modeling tool that calculates a geodetic velocity and strain field for a given fault model, and lets the user compare the modeled strain field with the strain field obtained from the user s data. Users may change parameters on-the-fly and obtain a real-time recalculation of the resulting strain field. Four data products are computed: maximum shear, dilatation, shear angle, and principal components. The current view and data dependencies are processed first. The remaining data products and views are then computed in a round-robin fashion to anticipate view changes. When an analysis or display parameter is changed, the affected data products and views are invalidated and progressively re-displayed as available. This software is designed to facilitate the derivation of the strain fields from the GPS and strain meter data that sample it to facilitate the understanding of the strengths and weaknesses of the strain field derivation from continuous GPS (CGPS) and other geodetic data from a variety of tectonic settings, to converge on the "best practices" strain derivation strategy for the Solid Earth Science ESDR System (SESES) project given the CGPS station distribution in the western U.S., and to provide SESES users with a scientific and educational tool to explore the strain field on their own with user-defined parameters.

  3. Assessment of technological characteristics of non-fat yoghurt manufactured with prebiotics and probiotic strains.

    PubMed

    Basyigit Kilic, Gülden; Akpinar Kankaya, Didem

    2016-01-01

    Microbiological, physicochemical, aroma and organic acid characteristics of non-fat yoghurt incorporated with β-glucan and probiotic Lactobacillus plantarum strains (AB6-25, AC18-82 and AK4-11) combination as adjunct culture were investigated during a 21 day storage period at 4 °C. Four treatment yoghurts contained 0.25, 0.5, 1 and 1.5 % β-glucan. Treatments also included probiotic combination and commercial culture. Treatments were compared with three controls produced containing commercial culture, commercial culture and probiotic combination, and commercial culture, Lactobacillus acidophilus and inulin. The results indicated that β-glucan promote the viability of lactobacilli. However, the addition of β-glucan (except 0.25 %) resulted in enhanced syneresis (P < 0.05). In general, the use of 0.25 % β-glucan had no significant effect on pH, fat, protein and organic acid content of non-fat yoghurt. The results obtained from this research demonstrated that the use of 0.25 % β-glucan has no adverse effect on the characteristics of non-fat yogurt produced with probiotic combination. PMID:26788009

  4. Protective Effect of Dual-Strain Probiotics in Preterm Infants: A Multi-Center Time Series Analysis

    PubMed Central

    Schwab, Frank; Garten, Lars; Geffers, Christine; Gastmeier, Petra; Piening, Brar

    2016-01-01

    Objective To determine the effect of dual-strain probiotics on the development of necrotizing enterocolitis (NEC), mortality and nosocomial bloodstream infections (BSI) in preterm infants in German neonatal intensive care units (NICUs). Design A multi-center interrupted time series analysis. Setting 44 German NICUs with routine use of dual-strain probiotics on neonatal ward level. Patients Preterm infants documented by NEO-KISS, the German surveillance system for nosocomial infections in preterm infants with birth weights below 1,500 g, between 2004 and 2014. Intervention Routine use of dual-strain probiotics containing Lactobacillus acidophilus and Bifidobacterium spp. (Infloran) on the neonatal ward level. Main outcome measures Incidences of NEC, overall mortality, mortality following NEC and nosocomial BSI. Results Data from 10,890 preterm infants in 44 neonatal wards was included in this study. Incidences of NEC and BSI were 2.5% (n = 274) and 15.0%, (n = 1631), respectively. Mortality rate was 6.1% (n = 665). The use of dual-strain probiotics significantly reduced the risk of NEC (HR = 0.48; 95% CI = 0.38–0.62), overall mortality (HR = 0.60, 95% CI = 0.44–0.83), mortality after NEC (HR = 0.51, 95% CI = 0.26–0.999) and nosocomial BSI (HR = 0.89, 95% CI = 0.81–0.98). These effects were even more pronounced in the subgroup analysis of preterm infants with birth weights below 1,000 g. Conclusion In order to reduce NEC and mortality in preterm infants, it is advisable to add routine prophylaxis with dual-strain probiotics to clinical practice in neonatal wards. PMID:27332554

  5. Mechanical strain isolator mount

    NASA Technical Reports Server (NTRS)

    James, Gordon E. (Inventor)

    1991-01-01

    Certain devices such as optical instruments must preserve their alignmental integrity while being subjected to mechanical strain. A mechanical strain isolator mount is provided to preserve the alignmental integrity of an alignment sensitive instrument. An alignment sensitive instrument is mounted on a rectangular base. Flexural legs are connected at their proximal ends to the rectangular base. Flexural legs are also spaced parallel to the sides. Mounting pads are connected to the legs at the distal end and the mechanical strain isolator mount is attached to the substrate by means of threaded bolts. When a mounting pad and its respective leg is subjected to lateral strain in either the X or Y direction via the substrate, the respective leg relieves the strain by bending in the direction of the strain. An axial strain on a mounting pad in the Z direction is relieved by a rotational motion of the legs in the direction of the strain. When the substrate is stress free, the flexural legs return to their original condition and thus preserve the original alignment integrity of the alignment sensitive instrument.

  6. Light intensity strain analysis

    NASA Technical Reports Server (NTRS)

    Williams, J. G. (Inventor)

    1973-01-01

    A process is described for the analysis of the strain field of structures subjected to large deformations involving a low modulus substrate having a high modulus, relatively thin coating. The optical properties of transmittance and reflectance are measured for the coated substrate while stressed and unstressed to indicate the strain field for the coated substrate.

  7. Strain gauge installation tool

    DOEpatents

    Conard, Lisa Marie

    1998-01-01

    A tool and a method for attaching a strain gauge to a test specimen by maaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  8. Mechanochromic polyurethane strain sensor

    NASA Astrophysics Data System (ADS)

    Cellini, F.; Khapli, S.; Peterson, S. D.; Porfiri, M.

    2014-08-01

    In this Letter, we study the mechanical and optical response of a thermoplastic polyurethane blended with 0.5 wt. % of bis(benzoxazolyl)stilbene dye. The mechanochromic behavior of the material is characterized in a uniaxial stress-relaxation test by simultaneously acquiring the applied force, mechanical deformation, and fluorescence emission. To offer insight into the stress-strain response of the polymer-dye blend, we adapt a classical nonlinear constitutive behavior for elastomeric materials that accounts for stress-induced softening. We correlate the fluorescent response with the mechanical strain to demonstrate the possibility of accurate strain sensing for a broad range of deformations during both loading and unloading.

  9. Strain gauge installation tool

    SciTech Connect

    Conard, Lisa Marie

    1997-12-01

    A tool and a method for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  10. Cholesterol-Lowering Potentials of Lactic Acid Bacteria Based on Bile-Salt Hydrolase Activity and Effect of Potent Strains on Cholesterol Metabolism In Vitro and In Vivo

    PubMed Central

    Lin, Pei-Pei; Hsieh, You-Miin; Zhang, Zi-yi; Wu, Hui-Ching; Huang, Chun-Chih

    2014-01-01

    This study collected different probiotic isolates from animal and plant sources to evaluate the bile-salt hydrolase activity of probiotics in vitro. The deconjugation potential of bile acid was determined using high-performance liquid chromatography. HepG2 cells were cultured with probiotic strains with high BSH activity. The triglyceride (TG) and apolipoprotein B (apo B) secretion by HepG2 cells were evaluated. Our results show that the BSH activity and bile-acid deconjugation abilities of Pediococcus acidilactici NBHK002, Bifidobacterium adolescentis NBHK006, Lactobacillus rhamnosus NBHK007, and Lactobacillus acidophilus NBHK008 were higher than those of the other probiotic strains. The cholesterol concentration in cholesterol micelles was reduced within 24 h. NBHK007 reduced the TG secretion by 100% after 48 h of incubation. NBHK002, NBHK006, and NBHK007 could reduce apo B secretion by 33%, 38%, and 39%, respectively, after 24 h of incubation. The product PROBIO S-23 produced a greater decrease in the total concentration of cholesterol, low-density lipoprotein, TG, and thiobarbituric acid reactive substance in the serum or livers of hamsters with hypercholesterolemia compared with that of hamsters fed with a high-fat and high-cholesterol diet. These results show that the three probiotic strains of lactic acid bacteria are better candidates for reducing the risk of cardiovascular disease. PMID:25538960

  11. Cholesterol-lowering potentials of lactic acid bacteria based on bile-salt hydrolase activity and effect of potent strains on cholesterol metabolism in vitro and in vivo.

    PubMed

    Tsai, Cheng-Chih; Lin, Pei-Pei; Hsieh, You-Miin; Zhang, Zi-yi; Wu, Hui-Ching; Huang, Chun-Chih

    2014-01-01

    This study collected different probiotic isolates from animal and plant sources to evaluate the bile-salt hydrolase activity of probiotics in vitro. The deconjugation potential of bile acid was determined using high-performance liquid chromatography. HepG2 cells were cultured with probiotic strains with high BSH activity. The triglyceride (TG) and apolipoprotein B (apo B) secretion by HepG2 cells were evaluated. Our results show that the BSH activity and bile-acid deconjugation abilities of Pediococcus acidilactici NBHK002, Bifidobacterium adolescentis NBHK006, Lactobacillus rhamnosus NBHK007, and Lactobacillus acidophilus NBHK008 were higher than those of the other probiotic strains. The cholesterol concentration in cholesterol micelles was reduced within 24 h. NBHK007 reduced the TG secretion by 100% after 48 h of incubation. NBHK002, NBHK006, and NBHK007 could reduce apo B secretion by 33%, 38%, and 39%, respectively, after 24 h of incubation. The product PROBIO S-23 produced a greater decrease in the total concentration of cholesterol, low-density lipoprotein, TG, and thiobarbituric acid reactive substance in the serum or livers of hamsters with hypercholesterolemia compared with that of hamsters fed with a high-fat and high-cholesterol diet. These results show that the three probiotic strains of lactic acid bacteria are better candidates for reducing the risk of cardiovascular disease. PMID:25538960

  12. What Are Sprains and Strains?

    MedlinePlus

    ... sprain, one or more ligaments is stretched or torn. What Causes a Sprain? Where Do Sprains Usually ... strain, a muscle or tendon is stretched or torn. What Causes Strains? A strain is caused by ...

  13. Sprains and Strains

    MedlinePlus

    ... people at risk for strains. Gymnastics, tennis, rowing, golf, and other sports that require extensive gripping can ... Trials and You was designed to help people learn more about clinical trials, why they matter, and ...

  14. Nanowires enabling strained photovoltaics

    SciTech Connect

    Greil, J.; Bertagnolli, E.; Lugstein, A.; Birner, S.

    2014-04-21

    Photovoltaic nano-devices have largely been relying on charge separation in conventional p-n junctions. Junction formation via doping, however, imposes major challenges in process control. Here, we report on a concept for photovoltaic energy conversion at the nano scale without the need for intentional doping. Our approach relies on charge carrier separation in inhomogeneously strained germanium nanowires (Ge NWs). This concept utilizes the strain-induced gradient in bandgap along tapered NWs. Experimental data confirms the feasibility of strain-induced charge separation in individual vapor-liquid-solid grown Ge NW devices with an internal quantum efficiency of ∼5%. The charge separation mechanism, though, is not inherently limited to a distinct material. Our work establishes a class of photovoltaic nano-devices with its opto-electronic properties engineered by size, shape, and applied strain.

  15. MEMS Graphene Strain Sensor

    NASA Astrophysics Data System (ADS)

    Young, Clinton Wen-Chieh

    Graphene is a two dimensional honeycomb structure of sp2 hybridized carbon atoms that has possibilities in many applications due to its excellent mechanical and electrical properties. One application for Graphene is in the field of sensors. Graphene's electronic properties do not degrade when it undergoes mechanical strain which is advantageous for strain sensors. In this thesis, certain properties, such as the piezo-resistivity and flexibility, of graphene will be explored to show how they can be utilized to make a strain sensing device. Our original fabrication process of patterning graphene and the transfer process of graphene onto a flexible substrate will be discussed. The development of a stretchable and flexible graphene based rosette strain sensor will also be detailed. Developing a novel, reliable patterning process for the graphene is the first step to manufacture a stretchable graphene based sensor. The graphene was patterned using a photolithography and etching process that was developed by our research team, then it was transferred to a flexible polymer substrate with the use of a combination of soft lithography and wet etching of the Ni foil with ferric chloride solution. Graphene patterning is an essential step in fabricating reliable and sensitive sensors. With this process, graphene can be consistently patterned into different shapes and sizes. To utilize the graphene as the sensing material it also needs to be transferred onto a flexible substrate. The innovative transfer process developed by our research team consistently adheres graphene to a flexible PDMS substrate while removing the original nickel substrate. In the end, the graphene was transferred from the metal substrate to the desired flexible substrate. This process was repeated multiple times to create a stack and multilayer device. While many graphene-based strain sensors have been developed, they are uni-directional and can only measure the strain applied on the sensor in a principle

  16. The atomic strain tensor

    SciTech Connect

    Mott, P.H.; Argon, A.S. ); Suter, U.W. Massachusetts Institute of Technology, Cambridge, MA )

    1992-07-01

    A definition of the local atomic strain increments in three dimensions and an algorithm for computing them is presented. An arbitrary arrangement of atoms is tessellated in to Delaunay tetrahedra, identifying interstices, and Voronoi polyhedra, identifying atomic domains. The deformation gradient increment tensor for interstitial space is obtained from the displacement increments of the corner atoms of Delaunay tetrahedra. The atomic site strain increment tensor is then obtained by finding the intersection of the Delaunay tetrahedra with the Voronoi polyhedra, accumulating the individual deformation gradient contributions of the intersected Delaunay tetrahedra into the Voronoi polyhedra. An example application is discussed, showing how the atomic strain clarifies the relative local atomic movement for a polymeric glass treated at the atomic level. 6 refs. 10 figs.

  17. Strain gauge installation tool

    DOEpatents

    Conard, L.M.

    1998-06-16

    A tool and a method are disclosed for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool. 6 figs.

  18. Diffusion on strained surfaces

    NASA Astrophysics Data System (ADS)

    Schroeder, M.; Wolf, D. E.

    1997-03-01

    The change of diffusion kinetics when elastic fields are present is discussed for diffusion on (001) surfaces of simple cubic, fcc and bcc lattices. All particles interact pairwise with a Lennard-Jones potential. The simple cubic lattice was stabilized by an anisotropic prefactor. It is found that generically compressive strain enhances diffusion whereas tensile strain increases the activation barrier. An approximately linear dependence of the barrier in a wide range of misfits is found. In heteroepitaxy, diffusion on top of large clusters is inhomogeneous and anisotropic. The kinetics close to edges and centers of islands are remarkably different. In many cases changes of binding energies are small compared to those of saddle point energies. Thermodynamic arguments (minimization of free energy) are not appropriate to describe diffusion on strained surfaces in these cases.

  19. Annihilation of strained vortices

    NASA Astrophysics Data System (ADS)

    Kimura, Yoshifumi

    2014-11-01

    As an initial stage of vortex reconnection, approach of nearly anti-parallel vortices has often been observed experimentally and studied numerically. Inspired by the recent experiment by Kleckner and Irvine on the dynamics of knotted vortices, we have studied the motion of two anti-parellel Burgers vortices driven by an axisymmetric linear straining field. We first extend the Burgers vortex solution which is a steady exact solution of the Navier-Stokes equation to a time-dependent exact solution. Then by superposing two such solutions, we investigate the annihilation process analytically. We can demonstrate that during the annihilation process the total vorticity decays exponentially on a time-scale proportional to the inverse of the rate of strain, even as the kinematic viscosity tends to 0. The analytic results are compared with the numerical simulations of two strained vortices with the vortex-vortex nonlinear interaction by Buntine and Pullin.

  20. Strain isolated ceramic coatings

    NASA Technical Reports Server (NTRS)

    Tolokan, R. P.; Brady, J. B.; Jarrabet, G. P.

    1985-01-01

    Plasma sprayed ceramic coatings are used in gas turbine engines to improve component temperature capability and cooling air efficiency. A compliant metal fiber strain isolator between a plasma sprayed ceramic coating and a metal substrate improves ceramic durability while allowing thicker coatings for better insulation. Development of strain isolated coatings has concentrated on design and fabrication of coatings and coating evaluation via thermal shock testing. In thermal shock testing, five types of failure are possible: buckling failure im compression on heat up, bimetal type failure, isothermal expansion mismatch failure, mudflat cracking during cool down, and long term fatigue. A primary failure mode for thermally cycled coatings is designated bimetal type failure. Bimetal failure is tensile failure in the ceramic near the ceramic-metal interface. One of the significant benefits of the strain isolator is an insulating layer protecting the metal substrate from heat deformation and thereby preventing bimetal type failure.

  1. Local Strain Evaluation of Strained-SOI Structures

    NASA Astrophysics Data System (ADS)

    Usuda, Koji; Mizuno, Tomohisa; Numata, Toshinori; Tezuka, Tsutomu; Sugiyama, Naoharu; Moriyama, Yoshihiko; Nakaharai, Shu; Takagi, Shin-Ichi

    The strain relaxation within a strained-Si on SiGe on insulator (SGOI) structure might be one of the key issues in development of strained-Si MOSFET devices for high-performance ULSIs. In order to investigate the strain relaxation within the thin strained-Si layers, a new characterization technique to directly evaluate a local strain variation in the layers is required. Hence, we have developed the nano-beam electron diffraction (NBD) method which has a lateral resolution of 10 nm and a strain resolution of 0.1%. In this paper, we discuss a detailed investigation of whether the NBD method could be utilized to clarify a strain in a strained-Si layer on the SGOI structures.

  2. ConStrains identifies microbial strains in metagenomic datasets

    PubMed Central

    Luo, Chengwei; Knight, Rob; Siljander, Heli; Knip, Mikael; Xavier, Ramnik J; Gevers, Dirk

    2015-01-01

    An important fraction of microbial diversity is harbored in strain individuality, so identification of conspecific bacterial strains is imperative for improved understanding of microbial community functions. Limitations in bioinformatics and sequencing technologies have to date precluded strain identification owing to difficulties in phasing short reads to faithfully recover the original strain-level genotypes, which have highly similar sequences. We present ConStrains, an open-source algorithm that identifies conspecific strains from metagenomic sequence data and reconstructs the phylogeny of these strains in microbial communities. The algorithm uses single-nucleotide polymorphism (SNP) patterns in a set of universal genes to infer within-species structures that represent strains. Applying ConStrains to simulated and host-derived data sets provides insights into microbial community dynamics. PMID:26344404

  3. ConStrains identifies microbial strains in metagenomic datasets.

    PubMed

    Luo, Chengwei; Knight, Rob; Siljander, Heli; Knip, Mikael; Xavier, Ramnik J; Gevers, Dirk

    2015-10-01

    An important fraction of microbial diversity is harbored in strain individuality, so identification of conspecific bacterial strains is imperative for improved understanding of microbial community functions. Limitations in bioinformatics and sequencing technologies have to date precluded strain identification owing to difficulties in phasing short reads to faithfully recover the original strain-level genotypes, which have highly similar sequences. We present ConStrains, an open-source algorithm that identifies conspecific strains from metagenomic sequence data and reconstructs the phylogeny of these strains in microbial communities. The algorithm uses single-nucleotide polymorphism (SNP) patterns in a set of universal genes to infer within-species structures that represent strains. Applying ConStrains to simulated and host-derived datasets provides insights into microbial community dynamics. PMID:26344404

  4. LC-MS/MS analysis of surface layer proteins as a useful method for the identification of lactobacilli from the Lactobacillus acidophilus group.

    PubMed

    Podlesny, Marcin; Jarocki, Piotr; Komon, Elwira; Glibowska, Agnieszka; Targonski, Zdzislaw

    2011-04-01

    For precise identification of a Lactobacillus K1 isolate, LC-MS/MS analysis of the putative surface layer protein was performed. The results obtained from LTQ-FT-ICR mass spectrometry confirmed that the analyzed protein spot is the surface layer protein originating from Lb. helveticus species. Moreover, the identified protein has the highest similarity with the surface layer protein from Lb. helveticus R0052. To evaluate the proteomic study, multilocus sequence analysis of selected housekeeping gene sequences was performed. Combination of 16S rRNA sequencing with partial sequences for the genes encoding the RNA polymerase alpha subunit (rpoA), phenylalanyl-tRNA synthase alpha subunit (pheS), translational elongation factor Tu (tuf), and Hsp60 chaperonins (groEL) also allowed to classify the analyzed isolate as Lb. helveticus. Further classification at the strain level was achieved by sequencing of the slp gene. This gene showed 99.8% identity with the corresponding slp gene of Lb. helveticus R0052, which is in good agreement with data obtained by nano-HPLC coupled to an LTQ-FT-ICR mass spectrometer. Finally, LC-MS/ MS analysis of surface layer proteins extracted from three other Lactobacillus strains proved that the proposed method is the appropriate molecular tool for the identification of S-layer-possessing lactobacilli at the species and even strain levels. PMID:21532327

  5. The strained state cosmology

    NASA Astrophysics Data System (ADS)

    Tartaglia, Angelo

    2016-01-01

    Starting from some relevant facts concerning the behavior of the universe over large scale and time span, the analogy between the geometric approach of General Relativity and the classical description of an elastic strained material continuum is discussed. Extending the elastic deformation approach to four dimensions it is shown that the accelerated expansion of the universe is recovered. The strain field of space-time reproduces properties similar to the ones ascribed to the dark energy currently called in to explain the accelerated expansion. The strain field in the primordial universe behaves as radiation, but asymptotically it reproduces the cosmological constant. Subjecting the theory to a number of cosmological tests confirms the soundness of the approach and gives an optimal value for the one parameter of the model, i.e. the bulk modulus of the space-time continuum. Finally various aspects of the Strained State Cosmology (SSC) are discussed and contrasted with some non-linear massive gravity theories. The possible role of structure topological defects is also mentioned. The conclusion is that SSC is at least as good as the ΛCDM standard cosmology, giving a more intuitive interpretation of the physical nature of the phenomena.

  6. Strain gage barometric transmitter

    NASA Technical Reports Server (NTRS)

    Viton, P.

    1977-01-01

    A strain gage barometric transmitter for measuring the atmospheric pressure in severe environmental conditions is described. This equipment specifications are presented and its performance assessed. It is shown that this barometric sensor can measure the atmospheric pressure with a precision of 0.5 mb during a 6 month period.

  7. Accurate strain measurements in highly strained Ge microbridges

    NASA Astrophysics Data System (ADS)

    Gassenq, A.; Tardif, S.; Guilloy, K.; Osvaldo Dias, G.; Pauc, N.; Duchemin, I.; Rouchon, D.; Hartmann, J.-M.; Widiez, J.; Escalante, J.; Niquet, Y.-M.; Geiger, R.; Zabel, T.; Sigg, H.; Faist, J.; Chelnokov, A.; Rieutord, F.; Reboud, V.; Calvo, V.

    2016-06-01

    Ge under high strain is predicted to become a direct bandgap semiconductor. Very large deformations can be introduced using microbridge devices. However, at the microscale, strain values are commonly deduced from Raman spectroscopy using empirical linear models only established up to ɛ100 = 1.2% for uniaxial stress. In this work, we calibrate the Raman-strain relation at higher strain using synchrotron based microdiffraction. The Ge microbridges show unprecedented high tensile strain up to 4.9% corresponding to an unexpected Δω = 9.9 cm-1 Raman shift. We demonstrate experimentally and theoretically that the Raman strain relation is not linear and we provide a more accurate expression.

  8. Potential probiotic attributes of a new strain of Bacillus coagulans CGMCC 9951 isolated from healthy piglet feces.

    PubMed

    Gu, Shao-Bin; Zhao, Li-Na; Wu, Ying; Li, Shi-Chang; Sun, Jian-Rui; Huang, Jing-Fang; Li, Dan-Dan

    2015-06-01

    A new strain of Bacillus coagulans CGMCC 9551, which has a broad range of antibacterial activities against six main pathogenic bacteria including Escherichia coli O8, Staphylococcus aureus, Salmonella enterica subsp. enterica serovar enteritidis, Streptococcus suis, Listeria monocytogenes and Pasteurella multocida, was isolated from healthy piglet feces. In adhesion assay, the isolate exhibited a stronger adhesion to pig intestinal mucus than that of B. subtilis JT143 and L. acidophilus LY24 respectively isolated from BioPlus(®)2B and FloraFIT(®) Probiotics (P < 0.05). The adhesion activity reached 44.5 ± 3.2, 48.9 ± 2.6, 42.6 ± 3.3 and 37.6 ± 2.4% to jejunum, ileum, transverse colon and sigmoid colon, separately. The survival rate of B. coagulans CGMCC 9551 was reduced by only 20% at 4 h exposure under 0.9% w/v bile salt. The strain was fully resistant to pH 2 for 2 h with 90.1 ± 3.5% survival and susceptible to 15 antibiotics commonly used in veterinary medicine. Additionally, the bacteria showed amylase, protease and cellulase activities. The safety assessment demonstrated the lack of toxicity potential in B. coagulans CGMCC 9551 by ligated rabbit ileal loop assay, acute and subchronic toxicity test. These results implied that that the new strain of B. coagulans CGMCC 9951 isolated from healthy piglet feces has promising probiotic characteristics and offers desirable opportunities for its successful commercialization as one excellent candidate probiotic. PMID:25752235

  9. Lactobacillus strains isolated from the vaginal microbiota of healthy women inhibit Prevotella bivia and Gardnerella vaginalis in coculture and cell culture.

    PubMed

    Atassi, Fabrice; Brassart, Dominique; Grob, Philipp; Graf, Federico; Servin, Alain L

    2006-12-01

    The purpose of this study was to investigate how human vaginal isolates of Lactobacillus acidophilus, Lactobacillus jensenii, Lactobacillus gasseri and Lactobacillus crispatus inhibit the vaginosis-associated pathogens Gardnerella vaginalis and Prevotella bivia. Results show that all the strains in coculture condition reduced the viability of G. vaginalis and P. bivia, but with differing degrees of efficacy. The treatment of G. vaginalis- and P. bivia-infected cultured human cervix epithelial HeLa cells with L. gasseri strain KS120.1 culture or cell-free culture supernatant (CFCS) results in the killing of the pathogens that are adhering to the cells. The mechanism of the killing activity is not attributable to low pH and the presence of lactic acid alone, but rather to the presence of hydrogen peroxide and proteolytic enzyme-resistant compound(s) present in the CFCSs. In addition, coculture of G. vaginalis or P. bivia with L. gasseri KS120.1 culture or KS120.1 bacteria results in inhibition of the adhesion of the pathogens onto HeLa cells. PMID:17059467

  10. Synbiotic Lactobacillus acidophilus NCFM and cellobiose does not affect human gut bacterial diversity but increases abundance of lactobacilli, bifidobacteria and branched-chain fatty acids: a randomized, double-blinded cross-over trial.

    PubMed

    van Zanten, Gabriella C; Krych, Lukasz; Röytiö, Henna; Forssten, Sofia; Lahtinen, Sampo J; Abu Al-Soud, Waleed; Sørensen, Søren; Svensson, Birte; Jespersen, Lene; Jakobsen, Mogens

    2014-10-01

    Probiotics, prebiotics, and combinations thereof, that is synbiotics, have been reported to modulate gut microbiota of humans. In this study, effects of a novel synbiotic on the composition and metabolic activity of human gut microbiota were investigated. Healthy volunteers (n = 18) were enrolled in a double-blinded, randomized, and placebo-controlled cross-over study and received synbiotic [Lactobacillus acidophilus NCFM (10(9) CFU) and cellobiose (5 g)] or placebo daily for 3 weeks. Fecal samples were collected and lactobacilli numbers were quantified by qPCR. Furthermore, 454 tag-encoded amplicon pyrosequencing was used to monitor the effect of synbiotic on the composition of the microbiota. The synbiotic increased levels of Lactobacillus spp. and relative abundances of the genera Bifidobacterium, Collinsella, and Eubacterium while the genus Dialister was decreased (P < 0.05). No other effects were found on microbiota composition. Remarkably, however, the synbiotic increased concentrations of branched-chain fatty acids, measured by gas chromatography, while short-chain fatty acids were not affected. PMID:25098489

  11. Effect of salt stress on morphology and membrane composition of Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidum, and their adhesion to human intestinal epithelial-like Caco-2 cells.

    PubMed

    Gandhi, Akanksha; Shah, Nagendra P

    2016-04-01

    The effects of NaCl reduction (10.0, 7.5, 5.0, 2.5, and 0% NaCl) and its substitution with KCl (50% substitution at each given concentration) on morphology of Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium longum was investigated using transmission electron microscopy. Changes in membrane composition, including fatty acids and phospholipids, were investigated using gas chromatography and thin layer chromatography. Adhesion ability of these bacteria to human intestinal epithelial-like Caco-2 cells, as affected by NaCl and its substitution with KCl, was also evaluated. Bacteria appeared elongated and the intracellular content appeared contracted when subjected to salt stress, as observed by transmission electron microscopy. Fatty acid content was altered with an increase in the ratio of unsaturated to saturated fatty acid content on increasing the NaCl-induced stress. Among the phospholipids, phosphatidylglycerol was reduced, whereas phosphatidylinositol and cardioplipin were increased when the bacteria were subjected to salt stress. There was a significant reduction in adhesion ability of the bacteria to Caco-2 cells when cultured in media supplemented with NaCl; however, the adhesion ability was improved on substitution with KCl at a given total salt concentration. The findings provide insights into bacterial membrane damage caused by NaCl. PMID:26874411

  12. The meaning of role strain.

    PubMed

    Ward, C R

    1986-01-01

    Explicating the meaning of the concept of role strain is important in role theory formulation, an area requiring further development to provide explanations and predictions for both patient and provider roles. In this analysis, the use of the term role strain is traced from the structural-functionalist and symbolic-interactionist perspectives. Descriptive, stipulative, and connotative definitions of role strain are derived, and necessary and relevant properties are proposed. Antecedent and intervening conditions for role strain are outlined from the literature. Role strain manifestations and empirical referents are presented, and an initial step is taken toward a theoretical formulation by defining role strain within the context of role stress. PMID:3079985

  13. Highly stretchable miniature strain sensor for large dynamic strain measurement

    DOE PAGESBeta

    Song, Bo; Yao, Shurong; Nie, Xu; Yu, Xun; Blecke, Jill

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages,more » as its gauge factor is 500 times of that of the conventional foil strain gages.« less

  14. Highly stretchable miniature strain sensor for large dynamic strain measurement

    SciTech Connect

    Song, Bo; Yao, Shurong; Nie, Xu; Yu, Xun; Blecke, Jill

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages, as its gauge factor is 500 times of that of the conventional foil strain gages.

  15. High temperature strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); You, Tao (Inventor)

    2011-01-01

    A ceramic strain gage based on reactively sputtered indium-tin-oxide (ITO) thin films is used to monitor the structural integrity of components employed in aerospace propulsion systems operating at temperatures in excess of 1500.degree. C. A scanning electron microscopy (SEM) of the thick ITO sensors reveals a partially sintered microstructure comprising a contiguous network of submicron ITO particles with well defined necks and isolated nanoporosity. Densification of the ITO particles was retarded during high temperature exposure with nitrogen thus stabilizing the nanoporosity. ITO strain sensors were prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures to incorporate more nitrogen into the films. Under these conditions, sintering and densification of the ITO particles containing these nitrogen rich grain boundaries was retarded and a contiguous network of nano-sized ITO particles was established.

  16. Novel strained superjunction VDMOS

    NASA Astrophysics Data System (ADS)

    Naugarhiya, Alok; Dubey, Shashank; Kondekar, Pravin N.

    2015-09-01

    In this paper, we have proposed novel strained superjunction (s-SJ) vertical double diffused MOS (VDMOS). Through channel engineering, we have introduced strain effects in s-SJ device using thin separate p-type silicon-germanium (p-SiGe) layer over silicon p-pillar. Further, we have designed process flow for the possible fabrication of s-SJ VDMOS. The proposed s-SJ devices fitted with less input capacitance (Cin) and 1.2∼3 times higher output current density than conventional SJ VDMOS. Therefore, 40% less gate charge (Qg) is required to turn-on the s-SJ VDMOS and Ron A is optimized in between 12% and 46%.

  17. Strain Release Amination

    PubMed Central

    Gianatassio, Ryan; Lopchuk, Justin M.; Wang, Jie; Pan, Chung-Mao; Malins, Lara R.; Prieto, Liher; Brandt, Thomas A.; Collins, Michael R.; Gallego, Gary M.; Sach, Neal W.; Spangler, Jillian E.; Zhu, Huichin; Zhu, Jinjiang; Baran, Phil S.

    2015-01-01

    To optimize drug candidates, modern medicinal chemists are increasingly turning to an unconventional structural motif: small, strained ring systems. However, the difficulty of introducing substituents such as bicyclo[1.1.1]pentanes, azetidines, or cyclobutanes often outweighs the challenge of synthesizing the parent scaffold itself. Thus, there is an urgent need for general methods to rapidly and directly append such groups onto core scaffolds. Here we report a general strategy to harness the embedded potential energy of effectively spring-loaded C–C and C–N bonds with the most oft-encountered nucleophiles in pharmaceutical chemistry, amines. Strain release amination can diversify a range of substrates with a multitude of desirable bioisosteres at both the early and late-stages of a synthesis. The technique has also been applied to peptide labeling and bioconjugation. PMID:26816372

  18. Interfacial residual thermal strain

    NASA Astrophysics Data System (ADS)

    Kasen, M.; Santoyo, R.

    A method has been developed for assessing the influence of polymer chemical composition and of processing parameters on the magnitude of residual stress developed in glass-fibre-reinforced composites subjected to various cure cycles and subsequently cooled to cryogenic temperatures. The test method was applied to nine resin types, including epoxy, vinyl ester, polyester, cyanate ester and phenolic formulations. Results suggest that polyester resin develops substantially less overall residual strain than do the other resin systems.

  19. Genealogies of mouse inbred strains.

    PubMed

    Beck, J A; Lloyd, S; Hafezparast, M; Lennon-Pierce, M; Eppig, J T; Festing, M F; Fisher, E M

    2000-01-01

    The mouse is a prime organism of choice for modelling human disease. Over 450 inbred strains of mice have been described, providing a wealth of different genotypes and phenotypes for genetic and other studies. As new strains are generated and others become extinct, it is useful to review periodically what strains are available and how they are related to each other, particularly in the light of available DNA polymorphism data from microsatellite and other markers. We describe the origins and relationships of inbred mouse strains, 90 years after the generation of the first inbred strain. Given the large collection of inbred strains available, and that published information on these strains is incomplete, we propose that all genealogical and genetic data on inbred strains be submitted to a common electronic database to ensure this valuable information resource is preserved and used efficiently. PMID:10615122

  20. Sports Hernia: Misdiagnosed Muscle Strain

    MedlinePlus

    ... Manipulative Treatment Becoming a DO Video Library Misdiagnosed Muscle Strain Can Be A Pain Page Content If ... speeds, sports hernias are frequently confused with common muscle strain ,” says Michael Sampson, DO, who practices in ...

  1. Construction of the Inbred Strain.

    PubMed

    Shinya, Minori

    2016-01-01

    Genetically homogeneous populations such as inbred strains are valuable experimental tools in various fields of biomedical analyses. In many animals, inbred strains are established by consecutive sib-pair mating for a minimum of 20 generations. As the generation proceeds, fitness of the population reduces usually. Therefore, in order to establish inbred strains, the important point is the selection of pairs in good condition at each generation. Here, I describe the procedure and tips for generating inbred strains in zebrafish. PMID:27464804

  2. Strain calibration of optical FBG-based strain sensors

    NASA Astrophysics Data System (ADS)

    Roths, Johannes; Wilfert, Andre; Kratzer, Peter; Jülich, Florian; Kuttler, Rolf

    2010-09-01

    A facility for strain sensitivity calibration of optical FBG-based strain sensors according to the German VDI/VDE 2660 guideline was established and characterized. Statistical analysis of several calibration measurement series performed with one single type of FBG strain sensor and application technique showed a reproducibility of 0.15%. Strain sensitivities for FBGs inscribed in two different types of optical fibres (GF1B and PR2008) showed significantly different strain sensitivities of k = 0.7885+/-0.0026 and k = 0.7758+/-0.0024, respectively.

  3. Strain actuated aeroelastic control

    NASA Technical Reports Server (NTRS)

    Lazarus, Kenneth B.

    1992-01-01

    Viewgraphs on strain actuated aeroelastic control are presented. Topics covered include: structural and aerodynamic modeling; control law design methodology; system block diagram; adaptive wing test article; bench-top experiments; bench-top disturbance rejection: open and closed loop response; bench-top disturbance rejection: state cost versus control cost; wind tunnel experiments; wind tunnel gust alleviation: open and closed loop response at 60 mph; wind tunnel gust alleviation: state cost versus control cost at 60 mph; wind tunnel command following: open and closed loop error at 60 mph; wind tunnel flutter suppression: open loop flutter speed; and wind tunnel flutter suppression: closed loop state cost curves.

  4. Strain balanced quantum posts

    SciTech Connect

    Alonso-Alvarez, D.; Alen, B.; Ripalda, J. M.; Llorens, J. M.; Taboada, A. G.; Briones, F.; Roldan, M. A.; Hernandez-Saz, J.; Hernandez-Maldonado, D.; Herrera, M.; Molina, S. I.

    2011-04-25

    Quantum posts are assembled by epitaxial growth of closely spaced quantum dot layers, modulating the composition of a semiconductor alloy, typically InGaAs. In contrast with most self-assembled nanostructures, the height of quantum posts can be controlled with nanometer precision, up to a maximum value limited by the accumulated stress due to the lattice mismatch. Here, we present a strain compensation technique based on the controlled incorporation of phosphorous, which substantially increases the maximum attainable quantum post height. The luminescence from the resulting nanostructures presents giant linear polarization anisotropy.

  5. [Echinococcus and strain concepts].

    PubMed

    Utük, Armağan Erdem; Simsek, Sami

    2008-01-01

    Hydatid disease (echinococcosis) is one of the most important parasitic zoonoses and remains a public health and economic problem all over the world. Echinococcus granulosus includes a number of genetic variants and, up to date, analyses of mitochondrial DNA sequences have identified ten distinct genetic types (genotypes G1-10). This categorization follows closely the pattern of strain variation emerging based on biological characteristics. The extensive variation in E. granulosus may influence life-cycle patterns, host specificity, development rate, antigenicity, transmission dynamics, sensitivity to chemotherapeutic agents, and pathology. In this review, the recent genetic characterizations of Echinococcus genus have been summarized. PMID:18351549

  6. Compensated High Temperature Strain Gage

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A device for measuring strain in substrates at high temperatures in which the thermally induced apparent strain is nulled is described. Two gages are used, one active gage and one compensating gage. Both gages are placed on the substrate to be gaged; the active gage is attached such that it responds to mechanical and thermally induced apparent strain while the compensating gage is attached such that it does not respond to mechanical strain and and measures only thermally induced apparent strain. A thermal blanket is placed over the two gages to maintain the gages at the same temperature. The two gages are wired as adjacent arms of a wheatstone bridge which nulls the thermally induced apparent strain giving a true reading of the mechanical strain in the substrate.

  7. Individual responses of mother sows to a probiotic Enterococcus faecium strain lead to different microbiota composition in their offspring.

    PubMed

    Starke, I C; Pieper, R; Neumann, K; Zentek, J; Vahjen, W

    2013-12-01

    Pregnant gilts were fed the probiotic Enterococcus faecium NCIMB10415 (SF68) one month before birth of piglets. DNA extracts of sow faeces taken in weekly intervals as well as extracts from the intestine of their offspring during the suckling period at 12 and 26 days of life were analysed by denaturing gradient gel electrophoresis (DGGE) and quantitative PCR. DGGE profiles of faecal bacterial communities from three out of six probiotic-fed sows were distinctly different from the control and other probiotic-fed sows at all time points after probiotic supplementation. The probiotic-fed sows and their offspring were therefore divided into non-responder (n=3) and responder (n=3) groups. The probiotic strain significantly increased faecal lactobacilli cell numbers in mother sows, which could be assigned to a significant increase of Lactobacillus amylovorus and Lactobacillus acidophilus. Responding sows showed a more pronounced increase than non-responding sows. Similarly, suckling piglets from non-responding and responding sows showed numeric and significant differences for different bacterial groups and species. DGGE profiles of suckling piglets from responding sows also grouped more closely than profiles from control animals. Non-metric multiscaling of suckling piglets showed the same tendency for suckling piglets, but not for post-weaning piglets. This study showed that the probiotic E. faecium strain modified the faecal microbiota of sows. This modification is carried over to their offspring, but leads to changes that do not mirror the quantitative composition in the mother sow. Individual variations in the bacterial composition of mother sows before probiotic feed intake may influence the impact of a probiotic in sows and their offspring. PMID:24311318

  8. The Effect of Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM Fermentation on Antioxidant Properties of Selected in Vitro Sprout Culture of Orthosiphon aristatus (Java Tea) as a Model Study

    PubMed Central

    Hunaefi, Dase; Akumo, Divine N.; Riedel, Heidi; Smetanska, Iryna

    2012-01-01

    High rosmarinic acid (RA) productivity has been achieved by applying jasmonic acid and yeast extract elicitors to the in vitro sprout culture of Orthosiphon aritatus (IOSC). The highest RA accumulation from three solvents was detected in IOSC after treatment with yeast extract (5 g/L). HPLC analysis clearly confirmed a drastic increase in RA subjected to yeast extract elicitation. Therefore, this yeast extract elicited IOSC was chosen for a lactic acid bacteria (LAB) fermentation study as a model system. This selected IOSC was subjected to different types of LAB fermentations (Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM) for different periods of time 24, 48 and 72 h. The LAB fermentations consisted of solid state fermentations (SSF) and liquid state fermentations (LSF) in a Digital Control Unit (DCU) fermenter system. The aim was to determine the effect of fermentation on the antioxidant properties of the plant extract. Results indicated that all types of LAB fermentation decreased the level of RA and total phenolics, however, a slight increase in total flavonoids and flavonols was observed in SSF samples. HPLC results confirmed that the longer the fermentation, the greater the reduction in RA content. The highest reduction was obtained in the sample of LSF inoculated with L. plantarum for a period of 72 h. The temperature of fermentation (37 °C) was predicted as contributing to the declining level in RA content. The loss in RA was concomitant with a loss of total antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, Trolox Equivalent Antioxidant Capacity (TEAC), and Superoxide Dismutase (SOD)-like activity). These results indicate that RA is the major contributor to the antioxidant activity of this plant. PMID:26787613

  9. Effect of drying methods of microencapsulated Lactobacillus acidophilus and Lactococcus lactis ssp. cremoris on secondary protein structure and glass transition temperature as studied by Fourier transform infrared and differential scanning calorimetry.

    PubMed

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

    2013-03-01

    Protective mechanisms of casein-based microcapsules containing mannitol on Lactobacillus acidophilus and Lactococcus lactis ssp. cremoris, changes in their secondary protein structures, and glass transition of the microcapsules were studied after spray- or freeze-drying and after 10 wk of storage in aluminum foil pouches containing different desiccants (NaOH, LiCl, or silica gel) at 25°C. An in situ Fourier transform infrared analysis was carried out to recognize any changes in fatty acids (FA) of bacterial cell envelopes, interaction between polar site of cell envelopes and microcapsules, and alteration of their secondary protein structures. Differential scanning calorimetry was used to determine glass transition of microcapsules based on glass transition temperature (T(g)) values. Hierarchical cluster analysis based on functional groups of cell envelopes and secondary protein structures was also carried out to classify the microencapsulated bacteria due to the effects of spray- or freeze-drying and storage for 10 wk. The results showed that drying process did not affect FA and secondary protein structures of bacteria; however, those structures were affected during storage depending upon the type of desiccant used. Interaction between exterior of bacterial cell envelopes and microencapsulant occurred after spray- or freeze-drying; however, these structures were maintained after storage in foil pouch containing sodium hydroxide. Method of drying and type of desiccants influenced the level of similarities of microencapsulated bacteria. Desiccants and method of drying affected glass transition, yet no T(g) ≤25°C was detected. This study demonstrated that the changes in FA and secondary structures of the microencapsulated bacteria still occurred during storage at T(g) above room temperature, indicating that the glassy state did not completely prevent chemical activities. PMID:23357021

  10. Identification, cloning, and nucleotide sequence of a silent S-layer protein gene of Lactobacillus acidophilus ATCC 4356 which has extensive similarity with the S-layer protein gene of this species.

    PubMed Central

    Boot, H J; Kolen, C P; Pouwels, P H

    1995-01-01

    The bacterial S-layer forms a regular structure, composed of a monolayer of one (glyco)protein, on the surfaces of many prokaryotic species. S-layers are reported to fulfil different functions, such as attachment structures for extracellular enzymes and major virulence determinants for pathogenic species. Lactobacillus acidophilus ATCC 4356, which originates from the human pharynx, possesses such an S-layer. No function has yet been assigned to the S-layer of this species. Besides the structural gene (slpA) for the S-layer protein (S-protein) which constitutes this S-layer, we have identified a silent gene (slpB), which is almost identical to slpA in two regions. From the deduced amino acid sequence, it appears that the mature SB-protein (44,884 Da) is 53% similar to the SA-protein (43,636 Da) in the N-terminal and middle parts of the proteins. The C-terminal parts of the two proteins are identical except for one amino acid residue. The physical properties of the deduced S-proteins are virtually the same. Northern (RNA) blot analysis shows that only the slpA gene is expressed in wild-type cells, in line with the results from sequencing and primer extension analyses, which reveal that only the slpA gene harbors a promoter, which is located immediately upstream of the region where the two genes are identical. The occurrence of in vivo chromosomal recombination between the two S-protein-encoding genes will be described elsewhere. PMID:8522531

  11. The Effect of Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM Fermentation on Antioxidant Properties of Selected in Vitro Sprout Culture of Orthosiphon aristatus (Java Tea) as a Model Study.

    PubMed

    Hunaefi, Dase; Akumo, Divine N; Riedel, Heidi; Smetanska, Iryna

    2012-01-01

    High rosmarinic acid (RA) productivity has been achieved by applying jasmonic acid and yeast extract elicitors to the in vitro sprout culture of Orthosiphon aritatus (IOSC). The highest RA accumulation from three solvents was detected in IOSC after treatment with yeast extract (5 g/L). HPLC analysis clearly confirmed a drastic increase in RA subjected to yeast extract elicitation. Therefore, this yeast extract elicited IOSC was chosen for a lactic acid bacteria (LAB) fermentation study as a model system. This selected IOSC was subjected to different types of LAB fermentations (Lactobacillus plantarum ATCC 8014 and Lactobacillus acidophilus NCFM) for different periods of time 24, 48 and 72 h. The LAB fermentations consisted of solid state fermentations (SSF) and liquid state fermentations (LSF) in a Digital Control Unit (DCU) fermenter system. The aim was to determine the effect of fermentation on the antioxidant properties of the plant extract. Results indicated that all types of LAB fermentation decreased the level of RA and total phenolics, however, a slight increase in total flavonoids and flavonols was observed in SSF samples. HPLC results confirmed that the longer the fermentation, the greater the reduction in RA content. The highest reduction was obtained in the sample of LSF inoculated with L. plantarum for a period of 72 h. The temperature of fermentation (37 °C) was predicted as contributing to the declining level in RA content. The loss in RA was concomitant with a loss of total antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, Trolox Equivalent Antioxidant Capacity (TEAC), and Superoxide Dismutase (SOD)-like activity). These results indicate that RA is the major contributor to the antioxidant activity of this plant. PMID:26787613

  12. Impact of inulin and okara on Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 viability in a fermented soy product and probiotic survival under in vitro simulated gastrointestinal conditions.

    PubMed

    Bedani, Raquel; Rossi, Elizeu Antonio; Isay Saad, Susana Marta

    2013-06-01

    The effect of inulin and/or okara flour on Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 viability in a fermented soy product (FSP) and on probiotic survival under in vitro simulated gastrointestinal conditions were investigated throughout 28 days of storage at 4 °C. Employing a 2(2) design, four FSP trials were produced from soymilk fermented with ABT-4 culture (La-5, Bb-12, and Streptococcus thermophilus): FSP (control); FSP-I (with inulin, 3 g/100 mL of soymilk); FSP-O (with okara, 5 g/100 mL); FSP-IO (with inulin + okara, ratio 3:5 g/100 mL). Probiotic viabilities ranged from 8 to 9 log cfu/g during the 28 days of storage, and inulin and/or okara flour did not affect the viability of La-5 and Bb-12. Bb-12 resistance to the artificial gastrointestinal juices was higher than for La-5, since the Bb-12 and La-5 populations decreased approximately 0.6 log cfu/g and 3.8 log cfu/g, respectively, throughout storage period. Even though the protective effect of inulin and/or okara flour on probiotic microorganisms was not significant, when compared to a fresh culture, the FSP matrix improved Bb-12 survival on day 1 of storage and may be considered a good vehicle for Bb-12 and could play an important role in probiotic protection against gastrointestinal juices. PMID:23541206

  13. Geodetic strain measurements in Washington.

    USGS Publications Warehouse

    Savage, J.C.; Lisowski, M.; Prescott, W.H.

    1981-01-01

    Two new geodetic measurements of strain accumulation in the state of Washington for the interval 1972-1979 are reported. Near Seattle the average principal strain rates are 0.07 + or - 0.03 mu strain/yr N19oW and -0.13 + or - 0.02 mu strain/yr N71oE, and near Richland (south central Washington) the average principal strain rates are -0.02 + or - 0.01 mu strain/yr N36oW and -0.04 + or - 0.01 mu strain/yr N54oE. Extension is taken as positive, and the uncertainties quoted are standard deviations. A measurement of shear strain accumulation (dilation not determined) in the epoch 1914- 1966 along the north coast of Vancouver Island by the Geodetic Survey of Canada indicates a marginally significant accumulation of right-lateral shear (0.06 + or - 0.03 mu rad/yr) across the plate boundary (N40oW strike). Although there are significant differences in detail, these strain measurements are roughly consistent with a crude dislocation model that represents subduction of the Juan de Fuca plate. The observed accumulation of strain implies that large, shallow, thrust earthquakes should be expected off the coast of Washington and British Columbia. However, this conclusion is not easily reconciled with either observations of elevation change along the Washington coast or the focal mechanism solutions for shallow earthquakes in Washington. -Authors

  14. Strain Engineering in Graphene

    NASA Astrophysics Data System (ADS)

    Castro Neto, Antonio

    2011-03-01

    Graphene is a unique example of a one atom thick metallic membrane. Hence, graphene brings together properties of soft and hard condensed matter systems. The elementary electronic excitations in graphene, the Dirac quasiparticles, couple in a singular way to structural distortions in the form of scalar and vector potentials. Therefore, graphene has an effective electrodynamics where structural deformations couple to the Dirac particles at equal footing to electric and magnetic fields. This so-called strain engineering of the electronic properties of graphene opens doors for a new paradigm in terms of electronic devices, where electronic properties can be manipulated at will using its membrane-like properties. I thank partial support from from DOE Grant DE-FG02-08ER46512 and ONR Grant MURI N00014-09-1-1063.

  15. Inhomogeneous strains in small particles

    NASA Astrophysics Data System (ADS)

    Marks, L. D.

    1985-02-01

    This paper considers the evidence for strains in small particles. Firstly, the dynamical electron diffraction theory for dark field imaging of small particles is briefly reviewed, considering primarily the effects of strain on wedge crystals and identifying the fingerprint of strain contrast effects under strong beam conditions. Evidence included herein and from published papers by other authors clearly shows inhomogeneous strain effects in both multiply twinned particles and single crystals. Considering these results and earlier reports of lattice parameter changes, there are problems with the uniqueness of these analyses, and the strains in the small single crystals are thought more likely to be due to interfacial stresses or contaminants than any intrinsic particle effect; there are so many different origins of this type of strain that we cannot with confidence isolate a unique source. It is emphasised that the uniqueness of any interpretation of experimental results from small particles must be very carefully considered.

  16. Thermal strain imaging: a review

    PubMed Central

    Seo, Chi Hyung; Shi, Yan; Huang, Sheng-Wen; Kim, Kang; O'Donnell, Matthew

    2011-01-01

    Thermal strain imaging (TSI) or temporal strain imaging is an ultrasound application that exploits the temperature dependence of sound speed to create thermal (temporal) strain images. This article provides an overview of the field of TSI for biomedical applications that have appeared in the literature over the past several years. Basic theory in thermal strain is introduced. Two major energy sources appropriate for clinical applications are discussed. Promising biomedical applications are presented throughout the paper, including non-invasive thermometry and tissue characterization. We present some of the limitations and complications of the method. The paper concludes with a discussion of competing technologies. PMID:22866235

  17. Hydrogen production from microbial strains

    DOEpatents

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  18. Strain in silicon nanowire beams

    NASA Astrophysics Data System (ADS)

    Ureña, Ferran; Olsen, Sarah H.; Šiller, Lidija; Bhaskar, Umesh; Pardoen, Thomas; Raskin, Jean-Pierre

    2012-12-01

    In this work, strain in silicon free standing beams loaded in uniaxial tension is experimentally and theoretically investigated for strain values ranging from 0 to 3.6%. The fabrication method allows multiple geometries (and thus strain values) to be processed simultaneously on the same wafer while being studied independently. An excellent agreement of strain determined by two non-destructive characterization techniques, Raman spectroscopy and mechanical displacement using scanning electron microscopy (SEM) markers, is found for all the sample lengths and widths. The measured data also show good agreement with theoretical predictions of strain based upon continuum mechanical considerations, giving validity to both measurement techniques for the entire range of strain values. The dependence of Young's modulus and fracture strain on size has also been analyzed. The Young's modulus is determined using SEM and compared with that obtained by resonance-based methods. Both methods produced a Young's modulus value close to that of bulk silicon with values obtained by resonance-based methods being slightly lower. Fracture strain is analyzed in 40 sets of samples with different beam geometries, yielding values up to 3.6%. The increase in fracture strain with decreasing beam width is compared with previous reports. Finally, the role of the surface on the mechanical properties is analyzed using UV and visible lasers having different penetration depths in silicon. The observed dependence of Raman shift on laser wavelength is used to assess the thermal conductivity of deformed silicon.

  19. Strain variation in corrugated graphene

    NASA Astrophysics Data System (ADS)

    Wang, Xuanye; Tantiwanichapan, Khwanchai; Christopher, Jason; Paiella, Roberto; Swan, Anna

    2015-03-01

    Raman spectroscopy is a powerful non-destructive technique for analyzing strain in graphene. Recently there has been interest in making corrugated graphene devices with varying spatial wavelengths Λ for plasmonic and THz applications. Transferring graphene onto corrugated substrates introduces strain, which if there was perfect clamping (high fraction) would cause a periodic strain variation. However, the strain variation for pattern size smaller than the diffraction limit λ makes it hard to precisely model the strain distribution. Here we present a detailed study on how strain varies in corrugated graphene with sub-diffraction limit periodicity Λ < λ. Mechanically exfoliated graphene was deposited onto sinusoidal shape silicon dioxide gratings with Λ=400 nm period using the pick and place transfer technique. We observed that the graphene is not rigidly clamped, but partially slides to relieve the strain. We model the linewidth variation to extract the local strain variation as well as the sliding in the presence of charge puddling in graphene. The method gives us a better understanding on graphene slippage and strain distribution in graphene on a corrugated substrate with sub-diffraction limit spatial period.

  20. Hypothetical strain-free oligoradicals

    PubMed Central

    Hoffmann, Roald; Eisenstein, Odile; Balaban, Alexandru T.

    1980-01-01

    Several new classes of oligoradicals free of angle strain are suggested and examined by means of molecular orbital calculations. The collapse products of these hypothetical radicals are highly strained molecules. Various electronic strategies for the stabilization of these oligoradicals have been explored. PMID:16592882

  1. Emerging Enteropathogenic Escherichia coli Strains?

    PubMed Central

    Irino, Kinue; Girão, Dennys M.; Girão, Valéria B.C.; Guth, Beatriz E.C.; Vaz, Tânia M.I.; Moreira, Fabiana C.; Chinarelli, Silvia H.; Vieira, Mônica A.M.

    2004-01-01

    Escherichia coli strains of nonenteropathogenic serogroups carrying eae but lacking the enteropathogenic E. coli adherence factor plasmid and Shiga toxin DNA probe sequences were isolated from patients (children, adults, and AIDS patients) with and without diarrhea in Brazil. Although diverse in phenotype and genotype, some strains are potentially diarrheagenic. PMID:15504277

  2. Difference Between Strain and Sprain.

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    Provided in this description of the differences between a strain (damage to the muscle or tendon) and a sprain (damage to the ligament) are definitions of mild, moderate, and severe (first, second, and third degree) strains and sprains. A final caution is given that these are two separate and distinct problems and should be treated as such. (DC)

  3. [Repetition Strain Injury

    PubMed

    Ribeiro

    1997-01-01

    Muscular-skeletal disorders of the upper limbs resulting from work involving repetition strain (RSI) are now the most frequent work-related diseases in early or late industrialized countries. The author maintains that in addition to being work-related diseases, RSIs are symbolic illnesses revealing the contradictions and social pathogenesis of the new cycle of development and crisis in capitalist production. Discussing the social and historical dimensions of this process, the author insists that the low efficacy of technical interventions by labor engineering, ergonomics, and clinical medicine in the prevention, early and adequate diagnosis, and treatment of such post-modern illnesses and the difficulty in rehabilitating and reincorporating such workers reflect precisely a broader determination of health and illness, since the appropriation, incorporation, and use of technological innovations and the new forms of work management are defined according to the exclusive interests of capital. Thus, a growing contingent of young workers (mainly females) from different labor categories are losing or under threat of losing their health and work capacity, two essential and closely linked public values. The solution to the SRI issue must be political and collective. PMID:10886940

  4. Dietary supplementation of a mixture of Lactobacillus strains enhances performance of broiler chickens raised under heat stress conditions

    NASA Astrophysics Data System (ADS)

    Faseleh Jahromi, Mohammad; Wesam Altaher, Yassir; Shokryazdan, Parisa; Ebrahimi, Roohollah; Ebrahimi, Mahdi; Idrus, Zulkifli; Tufarelli, Vincenzo; Liang, Juan Boo

    2016-07-01

    High ambient temperature is a major problem in commercial broiler production in the humid tropics because high producing broiler birds consume more feed, have higher metabolic activity, and thus higher body heat production. To evaluate the effects of two previously isolated potential probiotic strains ( Lactobacillus pentosus ITA23 and Lactobacillus acidophilus ITA44) on broilers growing under heat stress condition, a total of 192 chicks were randomly allocated into four treatment groups of 48 chickens each as follows: CL, birds fed with basal diet raised in 24 °C; PL, birds fed with basal diet plus 0.1 % probiotic mixture raised in 24 °C; CH, birds fed with basal diet raised in 35 °C; and PH, birds fed with basal diet plus 0.1 % probiotic mixture raised in 35 °C. The effects of probiotic mixture on the performance, expression of nutrient absorption genes of the small intestine, volatile fatty acids (VFA) and microbial population of cecal contents, antioxidant capacity of liver, and fatty acid composition of breast muscle were investigated. Results showed that probiotic positively affected the final body weight under both temperature conditions (PL and PH groups) compared to their respective control groups (CL and CH). Probiotic supplementation numerically improved the average daily gain (ADG) under lower temperature, but significantly improved ADG under the higher temperature ( P < 0.05) by sustaining high feed intake. Under the lower temperature environment, supplementation of the two Lactobacillus strains significantly increased the expression of the four sugar transporter genes tested (GLUT2, GLUT5, SGLT1, and SGLT4) indicating probiotic enhances the absorption of this nutrient. Similar but less pronounced effect was also observed under higher temperature (35 °C) condition. In addition, the probiotic mixture improved bacterial population of the cecal contents, by increasing beneficial bacteria and decreasing Escherichia coli population, which could be

  5. Dietary supplementation of a mixture of Lactobacillus strains enhances performance of broiler chickens raised under heat stress conditions.

    PubMed

    Faseleh Jahromi, Mohammad; Wesam Altaher, Yassir; Shokryazdan, Parisa; Ebrahimi, Roohollah; Ebrahimi, Mahdi; Idrus, Zulkifli; Tufarelli, Vincenzo; Liang, Juan Boo

    2016-07-01

    High ambient temperature is a major problem in commercial broiler production in the humid tropics because high producing broiler birds consume more feed, have higher metabolic activity, and thus higher body heat production. To evaluate the effects of two previously isolated potential probiotic strains (Lactobacillus pentosus ITA23 and Lactobacillus acidophilus ITA44) on broilers growing under heat stress condition, a total of 192 chicks were randomly allocated into four treatment groups of 48 chickens each as follows: CL, birds fed with basal diet raised in 24 °C; PL, birds fed with basal diet plus 0.1 % probiotic mixture raised in 24 °C; CH, birds fed with basal diet raised in 35 °C; and PH, birds fed with basal diet plus 0.1 % probiotic mixture raised in 35 °C. The effects of probiotic mixture on the performance, expression of nutrient absorption genes of the small intestine, volatile fatty acids (VFA) and microbial population of cecal contents, antioxidant capacity of liver, and fatty acid composition of breast muscle were investigated. Results showed that probiotic positively affected the final body weight under both temperature conditions (PL and PH groups) compared to their respective control groups (CL and CH). Probiotic supplementation numerically improved the average daily gain (ADG) under lower temperature, but significantly improved ADG under the higher temperature (P < 0.05) by sustaining high feed intake. Under the lower temperature environment, supplementation of the two Lactobacillus strains significantly increased the expression of the four sugar transporter genes tested (GLUT2, GLUT5, SGLT1, and SGLT4) indicating probiotic enhances the absorption of this nutrient. Similar but less pronounced effect was also observed under higher temperature (35 °C) condition. In addition, the probiotic mixture improved bacterial population of the cecal contents, by increasing beneficial bacteria and decreasing Escherichia coli population, which could

  6. Dietary supplementation of a mixture of Lactobacillus strains enhances performance of broiler chickens raised under heat stress conditions

    NASA Astrophysics Data System (ADS)

    Faseleh Jahromi, Mohammad; Wesam Altaher, Yassir; Shokryazdan, Parisa; Ebrahimi, Roohollah; Ebrahimi, Mahdi; Idrus, Zulkifli; Tufarelli, Vincenzo; Liang, Juan Boo

    2015-11-01

    High ambient temperature is a major problem in commercial broiler production in the humid tropics because high producing broiler birds consume more feed, have higher metabolic activity, and thus higher body heat production. To evaluate the effects of two previously isolated potential probiotic strains (Lactobacillus pentosus ITA23 and Lactobacillus acidophilus ITA44) on broilers growing under heat stress condition, a total of 192 chicks were randomly allocated into four treatment groups of 48 chickens each as follows: CL, birds fed with basal diet raised in 24 °C; PL, birds fed with basal diet plus 0.1 % probiotic mixture raised in 24 °C; CH, birds fed with basal diet raised in 35 °C; and PH, birds fed with basal diet plus 0.1 % probiotic mixture raised in 35 °C. The effects of probiotic mixture on the performance, expression of nutrient absorption genes of the small intestine, volatile fatty acids (VFA) and microbial population of cecal contents, antioxidant capacity of liver, and fatty acid composition of breast muscle were investigated. Results showed that probiotic positively affected the final body weight under both temperature conditions (PL and PH groups) compared to their respective control groups (CL and CH). Probiotic supplementation numerically improved the average daily gain (ADG) under lower temperature, but significantly improved ADG under the higher temperature (P < 0.05) by sustaining high feed intake. Under the lower temperature environment, supplementation of the two Lactobacillus strains significantly increased the expression of the four sugar transporter genes tested (GLUT2, GLUT5, SGLT1, and SGLT4) indicating probiotic enhances the absorption of this nutrient. Similar but less pronounced effect was also observed under higher temperature (35 °C) condition. In addition, the probiotic mixture improved bacterial population of the cecal contents, by increasing beneficial bacteria and decreasing Escherichia coli population, which could be

  7. High temperature strain measurement with a resistance strain gage

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen; Fichtel, ED; Mcdaniel, Amos

    1993-01-01

    A PdCr based electrical resistance strain gage was demonstrated in the laboratory to be a viable sensor candidate for static strain measurement at high temperatures. However, difficulties were encountered while transferring the sensor to field applications. This paper is therefore prepared for recognition and resolution of the problems likely to be encountered with PdCr strain gages in field applications. Errors caused by the measurement system, installation technique and lead wire attachment are discussed. The limitations and some considerations related to the temperature compensation technique used for this gage are also addressed.

  8. Recent advances in echocardiography: strain and strain rate imaging

    PubMed Central

    Mirea, Oana; Duchenne, Jurgen; Voigt, Jens-Uwe

    2016-01-01

    Deformation imaging by echocardiography is a well-established research tool which has been gaining interest from clinical cardiologists since the introduction of speckle tracking. Post-processing of echo images to analyze deformation has become readily available at the fingertips of the user. New parameters such as global longitudinal strain have been shown to provide added diagnostic value, and ongoing efforts of the imaging societies and industry aimed at harmonizing methods will improve the technique further. This review focuses on recent advances in the field of echocardiographic strain and strain rate imaging, and provides an overview on its current and potential future clinical applications. PMID:27158476

  9. Ferroelastic dynamics and strain compatibility

    NASA Astrophysics Data System (ADS)

    Lookman, T.; Shenoy, S. R.; Rasmussen, K. Ø.; Saxena, A.; Bishop, A. R.

    2003-01-01

    We derive underdamped evolution equations for the order-parameter (OP) strains of a proper ferroelastic material undergoing a structural transition, using Lagrangian variations with Rayleigh dissipation, and a free energy as a polynomial expansion in the N=n+Nop symmetry-adapted strains. The Nop strain equations are structurally similar in form to the Lagrange-Rayleigh one-dimensional strain dynamics of Bales and Gooding (BG), with “strain accelerations” proportional to a Laplacian acting on a sum of the free-energy strain derivative and frictional strain force assuming geometric linearity. The tensorial St. Venant’s elastic compatibility constraints that forbid defects, are used to determine the n non-order-parameter strains in terms of the OP strains, generating anisotropic and long-range OP contributions to the free energy, friction, and noise. The same OP equations are obtained by either varying the displacement vector components, or by varying the N strains subject to the Nc compatibility constraints. A Fokker-Planck equation, based on the BG dynamics in more than one dimension with noise terms, is set up. The BG dynamics corresponds to a set of nonidentical nonlinear (strain) oscillators labeled by wave vector k→, with competing short- and long-range couplings. The oscillators have different “strain-mass” densities ρ(k)˜1/k2 and dampings ˜1/ρ(k)˜k2, so the lighter large-k oscillators equilibrate first, corresponding to earlier formation of smaller-scale oriented textures. This produces a sequential-scale scenario for post-quench nucleation, elastic patterning, and hierarchical growth. Neglecting inertial effects yields a late-time dynamics for identifying extremal free-energy states, that is, of the time-dependent Ginzburg-Landau form, with nonlocal, anisotropic Onsager coefficients that become constants for special parameter values. We consider in detail the two-dimensional (2D) unit-cell transitions from a triangular to a centered

  10. Probiotic Dahi containing Lactobacillus acidophilus and Bifidobacterium bifidum modulates the formation of aberrant crypt foci, mucin-depleted foci, and cell proliferation on 1,2-dimethylhydrazine-induced colorectal carcinogenesis in Wistar rats.

    PubMed

    Mohania, Dheeraj; Kansal, Vinod K; Kruzliak, Peter; Kumari, Archana

    2014-08-01

    Aberrant crypt foci (ACF) and mucin-depleted foci (MDF) are pre-neoplastic lesions identified in the colon of carcinogen-treated rodents and in humans at high risk for colon cancer. The present study was carried out to divulge the protective potential of the probiotic Dahi containing Lactobacillus acidophilus LaVK2 and Bifidobacterium bifidum BbVK3 alone or in combination with piroxicam (PXC) on the development of early biomarkers of colorectal carcinogenesis in male Wistar rats administered 1,2-dimethylhydrazine (DMH). DMH was injected subcutaneously at the rate of 40 mg/kg body weight per animal twice a week for 2 weeks. A total of 120 male Wistar rats were randomly allocated to five groups, each group having 24 animals. The rats were fed with buffalo milk or probiotic supplement (20 grams) alone or as an adjunct with PXC in addition to a basal diet ad libitum for 32 weeks. Group I was offered buffalo milk (BM) and served as the control group. Group II was administered DMH along with BM and served as the DMH-control group; group III was administered BM-DMH-PXC, in which besides administering BM-DMH, PXC was also offered. Group IV was offered probiotic LaBb Dahi and DMH, and group V was offered both probiotic LaBb Dahi and PXC along with DMH. The rats were euthanized at the 8(th), 16(th), and 32(nd) week of the experiment and examined for development of ACF, aberrant crypts per ACF (AC/ACF), mucin-depleted foci (MDF), large MDF, and proliferating cell nuclear antigen (PCNA) labeling index. Administration of DMH in rats induced pre-neoplastic lesions (ACF and MDF) and increased the PCNA index in colorectal tissue. A significant (p<0.05) reduction in the number of ACF, AC/ACF, MDF, large MDF, and PCNA labeling index were observed in the probiotic LaBb Dahi group compared with the DMH control group. Feeding rats with LaBb Dahi or treatment with PXC diminished the initiation and progression of DMH-induced pre-neoplastic lesions and the PCNA index, and treatment with

  11. Low TCR nanocomposite strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); Chen, Ximing (Inventor)

    2012-01-01

    A high temperature thin film strain gage sensor capable of functioning at temperatures above 1400.degree. C. The sensor contains a substrate, a nanocomposite film comprised of an indium tin oxide alloy, zinc oxide doped with alumina or other oxide semiconductor and a refractory metal selected from the group consisting of Pt, Pd, Rh, Ni, W, Ir, NiCrAlY and NiCoCrAlY deposited onto the substrate to form an active strain element. The strain element being responsive to an applied force.

  12. High-temperature capacitive strain measurement system

    NASA Technical Reports Server (NTRS)

    Wilson, E. J.; Egger, R. L.

    1975-01-01

    Capacitive strain gage and signal conditioning system measures stress-induced strain and cancels thermal expansion strain at temperatures to 1,500 F (815 C). Gage does not significantly restrain or reinforce specimen.

  13. Anelastic Strain Recovery Analysis Code

    1995-04-05

    ASR4 is a nonlinear least-squares regression of Anelastic Strain Recovery (ASR) data for the purpose of determining in situ stress orientations and magnitudes. ASR4 fits the viscoelastic model of Warpinski and Teufel to measure ASR data, calculates the stress orientations directly, and stress magnitudes if sufficient input data are available. The code also calculates the stress orientation using strain-rosette equations, and it calculates stress magnitudes using Blanton''s approach, assuming sufficient input data are available.

  14. Bacterial Strain Diversity Within Wounds

    PubMed Central

    Kirkup, Benjamin C.

    2015-01-01

    Significance: Rare bacterial taxa (taxa of low relative frequency) are numerous and ubiquitous in virtually any sample—including wound samples. In addition, even the high-frequency genera and species contain multiple strains. These strains, individually, are each only a small fraction of the total bacterial population. Against the view that wounds contain relatively few kinds of bacteria, this newly recognized diversity implies a relatively high rate of migration into the wound and the potential for diversification during infection. Understanding the biological and medical importance of these numerous taxa is an important new element of wound microbiology. Recent Advances: Only recently have these numerous strains been discovered; the technology to detect, identify, and characterize them is still in its infancy. Multiple strains of both gram-negative and gram-positive bacteria have been found in a single wound. In the few cases studied, the distribution of the bacteria suggests microhabitats and biological interactions. Critical Issues: The distribution of the strains, their phenotypic diversity, and their interactions are still largely uncharacterized. The technologies to investigate this level of genomic detail are still developing and have not been largely deployed to investigate wounds. Future Directions: As advanced metagenomics, single-cell genomics, and advanced microscopy develop, the study of wound microbiology will better address the complex interplay of numerous individually rare strains with both the host and each other. PMID:25566411

  15. Optical Strain Measurement System Development

    NASA Technical Reports Server (NTRS)

    Lant, C. T.

    1985-01-01

    Investigations of physical phenomena affecting the durability of SSME components require measurement systems operational in hostile environments. The need for such instrumentation caused the definition and operation of an optical strain measurement system. This optical strain measurement system based on the speckle shift method is being developed. This is a noncontact, automatic method of measuring surface strain in one dimension that corrects for error due to rigid body motion. It provides a gauge length of 1 to 2 mm and allows the region of interest on the test specimen to be mapped point by point. The output is a graphics map of the points inspected on the specimen; data points is stored in quasi-real time. This is the first phase of a multiphase effort in optical strain measurement. The speckle pattern created by the test specimen is interpreted as high order interference fringes resulting from a random diffraction grating, being the natural surface roughness of the specimen. Strain induced on the specimen causes a change in spacing of the surface roughness, which in turn shifts the position of the interference pattern (speckles).

  16. Genome Sequence of Pseudomonas chlororaphis Strain 189

    PubMed Central

    Town, Jennifer; Audy, Patrice; Boyetchko, Susan M.

    2016-01-01

    Pseudomonas chlororaphis strain 189 is a potent inhibitor of the growth of the potato pathogen Phytophthora infestans. We determined the complete, finished sequence of the 6.8-Mbp genome of this strain, consisting of a single contiguous molecule. Strain 189 is closely related to previously sequenced strains of P. chlororaphis. PMID:27340063

  17. Measuring mine roof bolt strains

    DOEpatents

    Steblay, Bernard J.

    1986-01-01

    A mine roof bolt and a method of measuring the strain in mine roof bolts of this type are disclosed. According to the method, a flat portion on the head of the mine roof bolt is first machined. Next, a hole is drilled radially through the bolt at a predetermined distance from the bolt head. After installation of the mine roof bolt and loading, the strain of the mine roof bolt is measured by generating an ultrasonic pulse at the flat portion. The time of travel of the ultrasonic pulse reflected from the hole is measured. This time of travel is a function of the distance from the flat portion to the hole and increases as the bolt is loaded. Consequently, the time measurement is correlated to the strain in the bolt. Compensation for various factors affecting the travel time are also provided.

  18. Spin transport in graphene superlattice under strain

    NASA Astrophysics Data System (ADS)

    Sattari, Farhad

    2016-09-01

    In this paper, the spin-dependent transport and the spin polarization properties for graphene superlattice with Rashba spin-orbit interaction (RSOI) in the presence of zigzag and armchair direction strain are studied. It is found that for the zigzag direction strain the angular range of the spin-inversion can be efficiently controlled by the strain strength. In addition, the efficiency of spin-inversion and spin-dependent conductivity decreases by increasing the strain strength. When the armchair direction strain is applied to a monolayer graphene superlattice the spin polarization can be observed and increases by increasing the strain strength, whereas for the zigzag direction strain it is zero.

  19. Taxonomy of oxalotrophic Methylobacterium strains

    NASA Astrophysics Data System (ADS)

    Sahin, Nurettin; Kato, Yuko; Yilmaz, Ferah

    2008-10-01

    Most of the oxalotrophic bacteria are facultative methylotrophs and play important ecological roles in soil fertility and cycling of elements. This study gives a detailed picture of the taxonomy and diversity of these bacteria and provides new information about the taxonomical variability within the genus Methylobacterium. Twelve mesophilic, pink-pigmented, and facultatively methylotrophic oxalate-oxidizing strains were included in this work that had been previously isolated from the soil and some plant tissues by the potassium oxalate enrichment method. The isolates were characterized using biochemical tests, cellular lipid profiles, spectral characteristics of carotenoid pigments, G+C content of the DNA, and 16S rDNA sequencing. The taxonomic similarities among the strains were analyzed using the simple matching ( S SM) and Jaccard ( S J) coefficients, and the UPGMA clustering algorithm. The phylogenetic position of the strains was inferred by the neighbor-joining method on the basis of the 16S rDNA sequences. All isolates were Gram-negative, facultatively methylotrophic, oxidase and catalase positive, and required no growth factors. Based on the results of numerical taxonomy, the strains formed four closely related clusters sharing ≥85% similarity. Analysis of the 16S rDNA sequences demonstrated that oxalotrophic, pink-pigmented, and facultatively methylotrophic strains could be identified as members of the genus Methylobacterium. Except for M. variabile and M. aquaticum, all of the Methylobacterium type strains tested had the ability of oxalate utilization. Our results indicate that the capability of oxalate utilization seems to be an uncommon trait and could be used as a valuable taxonomic criterion for differentiation of Methylobacterium species.

  20. Photoacoustic spectroscopy of Entamoeba histolytica strains

    NASA Astrophysics Data System (ADS)

    Acosta-Avalos, D.; Alvarado-Gil, J. J.; Silva, E. F.; Orozco, E.; de Menezes, L. F.; Vargas, H.

    2005-06-01

    Pathogenic and non-pathogenic strains of E. histolytica are studied using photoacoustic spectroscopy. It is shown that the pathogenic strain presents a spectrum similar to that of iron sulfur proteins. The non-pathogenic strain does not show any relevant absorption at the studied wavelength range. The differences observed between the optical absorption spectra of both strains opens the possibility of using photoacoustic spectroscopy as a reliable and simple technique to identify different types of E. histolytica strains.

  1. Trials with a Strain Gauge.

    ERIC Educational Resources Information Center

    Auty, Geoff

    1996-01-01

    Describes an attempt to match the goals of the practical demonstration of the use of a strain gauge and the technical applications of science and responding to student questions in early trials, while keeping within the level of electronics in advanced physics. (Author/JRH)

  2. Virulence of 32 Salmonella Strains in Mice

    PubMed Central

    Swearingen, Matthew C.; Porwollik, Steffen; Desai, Prerak T.; McClelland, Michael; Ahmer, Brian M. M.

    2012-01-01

    Virulence and persistence in the BALB/c mouse gut was tested for 32 strains of Salmonella enterica for which genome sequencing is complete or underway, including 17 serovars within subspecies I (enterica), and two representatives of each of the other five subspecies. Only serovar Paratyphi C strain BAA1715 and serovar Typhimurium strain 14028 were fully virulent in mice. Three divergent atypical Enteritidis strains were not virulent in BALB/c, but two efficiently persisted. Most of the other strains in all six subspecies persisted in the mouse intestinal tract for several weeks in multiple repeat experiments although the frequency and level of persistence varied considerably. Strains with heavily degraded genomes persisted very poorly, if at all. None of the strains tested provided immunity to Typhimurium infection. These data greatly expand on the known significant strain-to-strain variation in mouse virulence and highlight the need for comparative genomic and phenotypic studies. PMID:22558320

  3. Mapping microscale strain heterogeneity during creep deformation

    NASA Astrophysics Data System (ADS)

    Quintanilla Terminel, A.; Evans, J.

    2013-12-01

    We use a new technique combining microfabrication technology and compression tests to map the strain field at a micrometric scale in polycrystalline materials. This technique allows us to map local strain while measuring macroscopic strain and rheological properties, and provides insight into the relative contribution of various plasticity mechanisms under varying creep conditions. The micro-strain mapping technique was applied to Carrara Marble under different deformation regimes, at 300 MPa and temperatures ranging from 200 to 700 °C. At 600 °C, strain of 10%, and strain rate of 3e-5s-1, the local strain at twin and grain boundaries is up to 5 times greater than the average sample strain. At these conditions, strains averaged across a particular grain may vary by as much as 100%, but the strain field becomes more homogeneous with increasing strain. For example, for the analyzed experiments, the average wavelength of the strain heterogeneity is 70 micrometers at 10% strain, but increases to 110 micrometers at 20%. For a strain of 10%, heterogeneity is increased at slower strain rate (at 1e-5s-1). This increase seems to be associated with a more important role of twin boundary and grain boundary migration. As expected, twin densities are markedly greater at the lower temperature, though it is still unclear whether the relative twin volume is greater. However, twin strains are still important at 600 °C and accommodate an average of 14 % of the total strain at 10% deformation and a strain rate of 3e-5s-1.

  4. Material mechanical characterization method for multiple strains and strain rates

    DOEpatents

    Erdmand, III, Donald L.; Kunc, Vlastimil; Simunovic, Srdjan; Wang, Yanli

    2016-01-19

    A specimen for measuring a material under multiple strains and strain rates. The specimen including a body having first and second ends and a gage region disposed between the first and second ends, wherein the body has a central, longitudinal axis passing through the first and second ends. The gage region includes a first gage section and a second gage section, wherein the first gage section defines a first cross-sectional area that is defined by a first plane that extends through the first gage section and is perpendicular to the central, longitudinal axis. The second gage section defines a second cross-sectional area that is defined by a second plane that extends through the second gage section and is perpendicular to the central, longitudinal axis and wherein the first cross-sectional area is different in size than the second cross-sectional area.

  5. Modelling to very high strains

    NASA Astrophysics Data System (ADS)

    Bons, P. D.; Jessell, M. W.; Griera, A.; Evans, L. A.; Wilson, C. J. L.

    2009-04-01

    Ductile strains in shear zones often reach extreme values, resulting in typical structures, such as winged porphyroclasts and several types of shear bands. The numerical simulation of the development of such structures has so far been inhibited by the low maximum strains that numerical models can normally achieve. Typical numerical models collapse at shear strains in the order of one to three. We have implemented a number of new functionalities in the numerical platform "Elle" (Jessell et al. 2001), which significantly increases the amount of strain that can be achieved and simultaneously reduces boundary effects that become increasingly disturbing at higher strain. Constant remeshing, while maintaining the polygonal phase regions, is the first step to avoid collapse of the finite-element grid required by finite-element solvers, such as Basil (Houseman et al. 2008). The second step is to apply a grain-growth routine to the boundaries of polygons that represent phase regions. This way, the development of sharp angles is avoided. A second advantage is that phase regions may merge or become separated (boudinage). Such topological changes are normally not possible in finite element deformation codes. The third step is the use of wrapping vertical model boundaries, with which optimal and unchanging model boundaries are maintained for the application of stress or velocity boundary conditions. The fourth step is to shift the model by a random amount in the vertical direction every time step. This way, the fixed horizontal boundary conditions are applied to different material points within the model every time step. Disturbing boundary effects are thus averaged out over the whole model and not localised to e.g. top and bottom of the model. Reduction of boundary effects has the additional advantage that model can be smaller and, therefore, numerically more efficient. Owing to the combination of these existing and new functionalities it is now possible to simulate the

  6. Strains

    MedlinePlus

    Pulled muscle ... can include: Pain and difficulty moving the injured muscle Discolored and bruised skin Swelling ... if you still have pain. Rest the pulled muscle for at least a day. If possible, keep ...

  7. Strain tolerant microfilamentary superconducting wire

    DOEpatents

    Finnemore, D.K.; Miller, T.A.; Ostenson, J.E.; Schwartzkopf, L.A.; Sanders, S.C.

    1993-02-23

    A strain tolerant microfilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments.

  8. Computational strain gradient crystal plasticity

    NASA Astrophysics Data System (ADS)

    Niordson, Christian F.; Kysar, Jeffrey W.

    2014-01-01

    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale.

  9. High Temperature Capacitive Strain Gage

    NASA Technical Reports Server (NTRS)

    Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.

    1990-01-01

    Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.

  10. Design of a strain-gage probe

    NASA Technical Reports Server (NTRS)

    Kolba, V. M.; Vetter, D. L.

    1969-01-01

    Strain-gage spacer probe uses the deflection of a leaf spring to measure strain in a long, slender beam nondestructively. The selected gage is of the smallest practical size, as thin as possible and yet of a standard type.

  11. Strain stiffening in collagen I networks.

    PubMed

    Motte, Stéphanie; Kaufman, Laura J

    2013-01-01

    Biopolymer gels exhibit strain stiffening that is generally not seen in synthetic gels. Here, we investigate the strain-stiffening behavior in collagen I gels that demonstrate elasticity derived from a variety of sources including crosslinking through telopeptides, bundling through low-temperature gelation, and exogenous crosslinking with genipin. In all cases, it is found that these gels exhibit strain stiffening; in general, onset of strain stiffening occurs earlier, yield strain is lower, and degree of strain stiffening is smaller in higher concentration gels and in those displaying thick fibril bundles. Recovery after exposure to high strains is substantial and similar in all gels, suggesting that much of the stiffening comes from reversible network deformations. A key finding of this study is that collagen I gels of identical storage and loss moduli may display different nonlinear responses and different capacities to recover from high strain. PMID:23097228

  12. Turbulent Plane Wakes Subjected to Successive Strains

    NASA Technical Reports Server (NTRS)

    Rogers, Michael M.

    2003-01-01

    Six direct numerical simulations of turbulent time-evolving strained plane wakes have been examined to investigate the response of a wake to successive irrotational plane strains of opposite sign. The orientation of the applied strain field has been selected so that the flow is the time-developing analogue of a spatially developing wake evolving in the presence of either a favourable or an adverse streamwise pressure gradient. The magnitude of the applied strain rate a is constant in time t until the total strain e(sup at) reaches about four. At this point, a new simulation is begun with the sign of the applied strain being reversed (the original simulation is continued as well). When the total strain is reduced back to its original value of one, yet another simulation is begun with the sign of the strain being reversed again back to its original sign. This process is done for both initially "favourable" and initially "adverse" strains, providing simulations for each of these strain types from three different initial conditions. The evolution of the wake mean velocity deficit and width is found to be very similar for all the adversely strained cases, with both measures rapidly achieving exponential growth at the rate associated with the cross-stream expansive strain e(sup at). In the "favourably" strained cases, the wake widths approach a constant and the velocity deficits ultimately decay rapidly as e(sup -2at). Although all three of these cases do exhibit the same asymptotic exponential behaviour, the time required to achieve this is longer for the cases that have been previously adversely strained (by at approx. equals 1). These simulations confirm the generality of the conclusions drawn in Rogers (2002) regarding the response of plane wakes to strain. The evolution of strained wakes is not consistent with the predictions of classical self-similar analysis; a more general equilibrium similarity solution is required to describe the results. At least for the cases

  13. Installing strain gauges on composite material

    NASA Astrophysics Data System (ADS)

    Shull, Larry

    The evolution of the strain gage is traced and problems associated with their use on composite materials are discussed. It is believed that the use of the computer in strain gage data systems has caused some of the attitude problems in measuring strains in composite materials. The performance of strain gages on filament-wound Kevlar pressure vessels is discussed as well as graphite composites during 1984-1986, surface preparation, gage location alignment.

  14. Temperature-Compensating Inactive Strain Gauge

    NASA Technical Reports Server (NTRS)

    Moore, Thomas C., Sr.

    1993-01-01

    Thermal contribution to output of active gauge canceled. High-temperature strain gauges include both active gauge wires sensing strains and inactive gauge wires providing compensation for thermal contributions to gauge readings. Inactive-gauge approach to temperature compensation applicable to commercially available resistance-type strain gauges operating at temperatures up to 700 degrees F and to developmental strain gauges operating at temperatures up to 2,000 degrees F.

  15. Piezoelectric field in strained GaAs.

    SciTech Connect

    Chow, Weng Wah; Wieczorek, Sebastian Maciej

    2005-11-01

    This report describes an investigation of the piezoelectric field in strained bulk GaAs. The bound charge distribution is calculated and suitable electrode configurations are proposed for (1) uniaxial and (2) biaxial strain. The screening of the piezoelectric field is studied for different impurity concentrations and sample lengths. Electric current due to the piezoelectric field is calculated for the cases of (1) fixed strain and (2) strain varying in time at a constant rate.

  16. Strain Monitoring of Flexible Structures

    NASA Technical Reports Server (NTRS)

    Litteken, Douglas A.

    2017-01-01

    , such as tensile testing, fatigue testing, and shear testing, but common measurement techniques cannot be used on fabric. Measuring strain in a material and during a test is a critical parameter for an engineer to monitor the structure during the test and correlate to an analytical model. The ability to measure strain in fabric structures is a challenge for NASA. Foil strain gauges, for example, are commonplace on metallic structures testing, but are extremely difficult to interface with a fabric substrate. New strain measuring techniques need to be developed for use with fabric structures. This paper investigates options for measuring strain in fabric structures for both ground testing and in-space structural health monitoring. It evaluates current commercially available options and outlines development work underway to build custom measurement solutions for NASA's fabric structures.

  17. Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains

    PubMed Central

    Gangaiah, Dharanesh; Webb, Kristen M.; Humphreys, Tricia L.; Fortney, Kate R.; Toh, Evelyn; Tai, Albert; Katz, Samantha S.; Pillay, Allan; Chen, Cheng-Yen; Roberts, Sally A.; Munson, Robert S.; Spinola, Stanley M.

    2015-01-01

    Background Although cutaneous ulcers (CU) in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU) and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin? Methodology/Principal Findings To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya) and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin. Conclusions/Significance These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions. PMID:26147869

  18. Modal strain energies in COSMIC NASTRAN

    NASA Technical Reports Server (NTRS)

    Snyder, B. D.; Venkayya, V. B.

    1989-01-01

    A computer program was developed to take a NASTRAN output file from a normal modes analysis and calculate the modal strain energies of selected elements. The FORTRAN program can determine the modal strain energies for CROD, CBAR, CELAS, CTRMEM, CQDMEM2, and CSHEAR elements. Modal strain energies are useful in estimating damping in structures.

  19. Strains and Sprains Are a Pain

    MedlinePlus

    ... move the injured part, and you may even think you have broken a bone . How Does a Strain or Sprain Happen? Strains often happen when you put a lot of pressure on a muscle or you push it too far, such as when lifting a heavy object. Strains can be more likely to happen if ...

  20. Strainrange partitioning: A total strain range version

    NASA Technical Reports Server (NTRS)

    Halford, G. R.; Saltsman, J. F.

    1983-01-01

    Procedures are presented for expressing the Strainrange Partitioning (SRP) method for creep fatigue life prediction in terms of total strain range. Inelastic and elastic strain-range - life relations are summed to give total strain-range - life relations. The life components due to inelastic strains are dealt with using conventional SRP procedures while the life components due to elastic strains are expressed as families of time-dependent terms for each type of SRP cycle. Cyclic constitutive material behavior plays an important role in establishing the elastic strain-range - life relations as well as the partitioning of the inelastic strains. To apply the approach, however, it is not necessary to have to determine the magnitude of the inelastic strain range. The total strain SRP approach is evaluated and verified using two nickel base superalloys, AF2-1DA and Rene 95. Excellent agreement is demonstrated between observed and predicted cyclic lifetimes with 70 to 80 percent of the predicted lives falling within factors of two of the observed lives. The total strain-range SRP approach should be of considerable practical value to designers who are faced with creep-fatigue problems for which the inelastic strains cannot be calculated with sufficient accuracy to make reliable life predictions by the conventional inelastic strain range SRP approach.

  1. Siderotyping of Antarctic fluorescent Pseudomonas strains.

    PubMed

    Geoffroy, V A; Meyer, J M

    2004-07-01

    Five fluorescent Pseudomonas strains isolated from Antarctica have been previously recognized as producing three structurally different pyoverdines. In the present work, siderotyping procedures have been used to classify these strains, together with 1282 isolates of different origins, into siderovars. The strain biodiversity encountered within each siderovar, as well as the potential taxonomic value of the siderovars, are described and discussed. It is concluded that a majority of antarctic strains are commonly distributed worldwide. One strain, however, presenting a particular pyoverdine structure found in a unique other isolate, was apparently much more specific to cold environment. PMID:15559975

  2. Progress in optical strain measurement system development

    NASA Technical Reports Server (NTRS)

    Lant, Christian T.; Qaqish, Walid

    1987-01-01

    A laser speckle strain measurement system has been built and tested for the NASA Lewis Research Center. The system is based on a speckle shift technique, which automatically corrects for error due to rigid body motion, and provides a near real time measure of strain. The first stage of a multiphase effort to develop an optical strain gauge capable of mapping in two dimensions the strain on the surface of a hot specimen is discussed. The objectives of this first phase have been to provide a noncontact, one-dimensional, differential strain gauge for experimental purposes, and to determine the maximum open air temperature limit of the system.

  3. Strain Engineering of Transition Metal Dichalcogenides

    NASA Astrophysics Data System (ADS)

    Dadgar, Ali; Pasupathy, Abhay; Herman, Irving; Wang, Dennis; Kang, Kyungnam; Yang, Eui-Hyeok

    The application of strain to materials can cause changes to bandwidth, effective masses, degeneracies and even structural phases. In the case of the transition metal dichalcogenide (TMD) semiconductors, small strain (around 1 percent) is expected to change band gaps and mobilities, while larger strains are expected to cause phase changes from the triangular 2H phase to orthorhombic 1T' phases. We will describe experimental techniques to apply small and large (around 10 percent) strains to one or few layer samples of the TMD semiconductors, and describe the effect of the strain using optical (Raman, photoluminescence) and cryogenic transport techniques.

  4. Demonstration test of burner liner strain measurements using resistance strain gages

    NASA Technical Reports Server (NTRS)

    Grant, H. P.; Anderson, W. L.

    1984-01-01

    A demonstration test of burner liner strain measurements using resistance strain gages as well as a feasibility test of an optical speckle technique for strain measurement are presented. The strain gage results are reported. Ten Kanthal A-1 wire strain gages were used for low cycle fatigue strain measurements to 950 K and .002 apparent strain on a JT12D burner can in a high pressure (10 atmospheres) burner test. The procedure for use of the strain gages involved extensive precalibration and postcalibration to correct for cooling rate dependence, drift, and temperature effects. Results were repeatable within + or - .0002 to .0006 strain, with best results during fast decels from 950 K. The results agreed with analytical prediction based on an axisymmetric burner model, and results indicated a non-uniform circumferential distribution of axial strain, suggesting temperature streaking.

  5. Strain flexibility identification of bridges from long-gauge strain measurements

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Xia, Qi; Cheng, YuYao; Wu, ZhiShen

    2015-10-01

    Strain flexibility, defined as the strain response of a structure's element to a unit input force, is import for structural safety evaluation, but its identification is seldom investigated. A novel long-gauge fiber optic sensor has been developed to measure the averaged strain within a long gauge length. Its advantage of measuring both local and global information of the structure offers an excellent opportunity of developing the strain flexibility identification theory. In this article, the method to identify structural strain flexibility from long-gauge dynamic strain measurements is proposed. It includes the following main steps: (a) macro strain frequency response function (FRF) estimation from macro strain measurements and its feature characterization; (b) general strain modal parameter identification; (c) scaling factor calculation, and (d) strain flexibility identification. Numerical and experimental examples successfully verify the effectiveness of the proposed method.

  6. Job Strain in Physical Therapists

    PubMed Central

    Campo, Marc A.; Weiser, Sherri; Koenig, Karen L.

    2009-01-01

    Background: Job stress has been associated with poor outcomes. In focus groups and small-sample surveys, physical therapists have reported high levels of job stress. Studies of job stress in physical therapy with larger samples are needed. Objective: The purposes of this study were: (1) to determine the levels of psychological job demands and job control reported by physical therapists in a national sample, (2) to compare those levels with national norms, and (3) to determine whether high demands, low control, or a combination of both (job strain) increases the risk for turnover or work-related pain. Design: This was a prospective cohort study with a 1-year follow-up period. Methods: Participants were randomly selected members of the American Physical Therapy Association (n=882). Exposure assessments included the Job Content Questionnaire (JCQ), a commonly used instrument for evaluation of the psychosocial work environment. Outcomes included job turnover and work-related musculoskeletal disorders. Results: Compared with national averages, the physical therapists reported moderate job demands and high levels of job control. About 16% of the therapists reported changing jobs during follow-up. Risk factors for turnover included high job demands, low job control, job strain, female sex, and younger age. More than one half of the therapists reported work-related pain. Risk factors for work-related pain included low job control and job strain. Limitations: The JCQ measures only limited dimensions of the psychosocial work environment. All data were self-reported and subject to associated bias. Conclusions: Physical therapists’ views of their work environments were positive, including moderate levels of demands and high levels of control. Those therapists with high levels of demands and low levels of control, however, were at increased risk for both turnover and work-related pain. Physical therapists should consider the psychosocial work environment, along with other

  7. Straining graphene using thin film shrinkage methods.

    PubMed

    Shioya, Hiroki; Craciun, Monica F; Russo, Saverio; Yamamoto, Michihisa; Tarucha, Seigo

    2014-03-12

    Theoretical works suggest the possibility and usefulness of strain engineering of graphene by predicting remarkable properties, such as Dirac cone merging, bandgap opening and pseudo magnetic field generation. However, most of these predictions have not yet been confirmed because it is experimentally difficult to control the magnitude and type (e.g., uniaxial, biaxial, and so forth) of strain in graphene devices. Here we report two novel methods to apply strain without bending the substrate. We employ thin films of evaporated metal and organic insulator deposited on graphene, which shrink after electron beam irradiation or heat application. These methods make it possible to apply both biaxial strain and in-plane isotropic compressive strain in a well-controlled manner. Raman spectroscopy measurements show a clear splitting of the degenerate states of the G-band in the case of biaxial strain, and G-band blue shift without splitting in the case of in-plane isotropic compressive strain. In the case of biaxial strain application, we find out the ratio of the strain component perpendicular to the stretching direction is at least three times larger than what was previously observed, indicating that shrinkage of the metal or organic insulator deposited on graphene induces both tensile and compressive strain in this atomically thin material. Our studies present for the first time a viable way to apply strain to graphene without the need to bend the substrate. PMID:24490629

  8. Straining Graphene Using Thin Film Shrinkage Methods

    PubMed Central

    2014-01-01

    Theoretical works suggest the possibility and usefulness of strain engineering of graphene by predicting remarkable properties, such as Dirac cone merging, bandgap opening and pseudo magnetic field generation. However, most of these predictions have not yet been confirmed because it is experimentally difficult to control the magnitude and type (e.g., uniaxial, biaxial, and so forth) of strain in graphene devices. Here we report two novel methods to apply strain without bending the substrate. We employ thin films of evaporated metal and organic insulator deposited on graphene, which shrink after electron beam irradiation or heat application. These methods make it possible to apply both biaxial strain and in-plane isotropic compressive strain in a well-controlled manner. Raman spectroscopy measurements show a clear splitting of the degenerate states of the G-band in the case of biaxial strain, and G-band blue shift without splitting in the case of in-plane isotropic compressive strain. In the case of biaxial strain application, we find out the ratio of the strain component perpendicular to the stretching direction is at least three times larger than what was previously observed, indicating that shrinkage of the metal or organic insulator deposited on graphene induces both tensile and compressive strain in this atomically thin material. Our studies present for the first time a viable way to apply strain to graphene without the need to bend the substrate. PMID:24490629

  9. Numerical demonstration of MEMS strain sensor

    NASA Astrophysics Data System (ADS)

    Saboonchi, Hossain; Ozevin, Didem

    2012-04-01

    Silicon has piezoresistive property that allows designing strain sensor with higher gauge factor compared to conventional metal foil gauges. The sensing element can be micro-scale using MEMS, which minimizes the effect of strain gradient on measurement at stress concentration regions such as crack tips. The challenge of MEMS based strain sensor design is to decouple the sensing element from substrate for true strain measurement and to compensate the temperature effect on the piezoresistive coefficients of silicon. In this paper, a family of MEMS strain sensors with different geometric designs is introduced. Each strain sensor is made of single crystal silicon and manufactured using deposition/ etching/oxidation steps on a n- doped silicon wafer in (100) plane. The geometries include sensing element connected to the free heads of U shape substrate, a set of two or more sensing elements in an array in order to capture strain gradients and two directional sensors. The response function and the gauge factor of the strain sensors are identified using multi-physics models that combine structural and electrical behaviors of sensors mounted on a strained structure. The relationship between surface strain and strain at microstructure is identified numerically in order to include the relationship in the response function calculation.

  10. Thick film wireless and powerless strain sensor

    NASA Astrophysics Data System (ADS)

    Jia, Yi; Sun, Ke

    2006-03-01

    The development of an innovative wireless strain sensing technology has a great potential to extend its applications in manufacturing, civil engineering and aerospace industry. This paper presents a novel wireless and powerless strain sensor with a multi-layer thick film structure. The sensor employs a planar inductor (L) and capacitive transducer (C) resonant tank sensing circuit, and a strain sensitive material of a polarized polyvinylidene fluoride (PVDF) piezoelectric thick film to realize the wireless strain sensing by strain to frequency conversion and to receive radio frequency electromagnetic energy for powering the sensor. The prototype sensor was designed and fabricated. The results of calibration on a strain constant cantilever beam show a great linearity and sensitivity about 0.0013 in a strain range of 0-0.018.

  11. Strain engineering of graphene: a review

    NASA Astrophysics Data System (ADS)

    Si, Chen; Sun, Zhimei; Liu, Feng

    2016-02-01

    Graphene has intrigued the science community by many unique properties not found in conventional materials. In particular, it is the strongest two-dimensional material ever measured, being able to sustain reversible tensile elastic strain larger than 20%, which yields an interesting possibility to tune the properties of graphene by strain and thus opens a new field called ``straintronics''. In this article, the current progress in the strain engineering of graphene is reviewed. We first summarize the strain effects on the electronic structure and Raman spectra of graphene. We then highlight the electron-phonon coupling greatly enhanced by the biaxial strain and the strong pseudomagnetic field induced by the non-uniform strain with specific distribution. Finally, the potential application of strain-engineering in the self-assembly of foreign atoms on the graphene surface is also discussed. Given the short history of graphene straintronics research, the current progress has been notable, and many further advances in this field are expected.

  12. Preliminary probiotic and technological characterization of Pediococcus pentosaceus strain KID7 and in vivo assessment of its cholesterol-lowering activity

    PubMed Central

    Damodharan, Karthiyaini; Lee, Young Sil; Palaniyandi, Sasikumar A.; Yang, Seung Hwan; Suh, Joo-Won

    2015-01-01

    The study was aimed to characterize the probiotic properties of a Pediococcus pentosaceus strain, KID7, by in vitro and in vivo studies. The strain possessed tolerance to oro-gastrointestinal transit, adherence to the Caco-2 cell line, and antimicrobial activity. KID7 exhibited bile salt hydrolase activity and cholesterol-lowering activity, in vitro. In vivo cholesterol-lowering activity of KID7 was studied using atherogenic diet-fed hypercholesterolemic mice. The experimental animals (C57BL/6J mice) were divided into 4 groups viz., normal diet-fed group (NCD), atherogenic diet-fed group (HCD), atherogenic diet- and KID7-fed group (HCD-KID7), and atherogenic diet- and Lactobacillus acidophilus ATCC 43121-fed group (HCD-L.ac) as positive control. Serum total cholesterol (T-CHO) level was significantly decreased by 19.8% in the HCD-KID7 group (P < 0.05), but not in the HCD-L.ac group compared with the HCD group. LDL cholesterol levels in both HCD-KID7 and HCD-L.ac groups were decreased by 35.5 and 38.7%, respectively, compared with HCD group (both, P < 0.05). Glutamyl pyruvic transaminase (GPT) level was significantly lower in the HCD-KID7 and HCD-L.ac groups compared to HCD group and was equivalent to that of the NCD group. Liver T-CHO levels in the HCD-KID7 group were reduced significantly compared with the HCD group (P < 0.05) but not in the HCD-L.ac group. Analysis of expression of genes associated with lipid metabolism in liver showed that low-density lipoprotein receptor (LDLR), cholesterol-7α-hydroxylase (CYP7A1) and apolipoprotein E (APOE) mRNA expression was significantly increase in the HCD-KID7 group compared to the HCD group. Furthermore, KID7 exhibited desired viability under freeze-drying and subsequent storage conditions with a combination of skim milk and galactomannan. P. pentosaceus KID7 could be a potential probiotic strain, which can be used to develop cholesterol-lowering functional food after appropriate human clinical trials. PMID:26300852

  13. Differential receptor usage by measles virus strains.

    PubMed

    Bartz, R; Firsching, R; Rima, B; ter Meulen, V; Schneider-Schaulies, J

    1998-05-01

    Recently, we demonstrated that infection of cells with all measles virus (MV) strains tested was inhibited by antibodies against CD46, although not all strains caused downregulation of the MV receptor CD46 from the surface of human cells. We now show that infection of cells with MV strain WTFb, a variant of wild-type isolate WTF which has been isolated and propagated on human BJAB cells, is not inhibited by antibodies against CD46. In contrast, infection of cells with the closely related strain WTFv, a Vero cell-adapted variant of WTF, is inhibited by antibodies against CD46. This observation led us to investigate the interaction of these viruses and the vaccine strain Edmonston (Edm) with CD46 and target cells. Cellular receptors with high affinity binding for WTFb are present on BJAB cells, but not on transfected CD46-expressing CHO cells. In contrast to the Edm strain, virus particles and solubilized envelope glycoproteins of WTFb have a very limited binding capacity to CD46. Furthermore, we show that recombinant soluble CD46 either does not bind, or binds very weakly, to WTFb glycoproteins expressed on the cell surface. Our findings indicate that wild-type MV strain WTFb and vaccine strain Edm use different binding sites on human cells. In addition, the results suggest that MV strains may alternatively use CD46 and an unknown molecule as receptors, and that the degree of usage of both receptors may be MV strain-specific. PMID:9603316

  14. Comparison of Strain Rosettes and Digital Image Correlation for Measuring Vertebral Body Strain.

    PubMed

    Gustafson, Hannah; Siegmund, Gunter; Cripton, Peter

    2016-05-01

    Strain gages are commonly used to measure bone strain, but only provide strain at a single location. Digital image correlation (DIC) is an optical technique that provides the displacement, and therefore strain, over an entire region of interest on the bone surface. This study compares vertebral body strains measured using strain gages and DIC. The anterior surfaces of 15 cadaveric porcine vertebrae were prepared with a strain rosette and a speckled paint pattern for DIC. The vertebrae were loaded in compression with a materials testing machine, and two high-resolution cameras were used to image the anterior surface of the bones. The mean noise levels for the strain rosette and DIC were 1 με and 24 με, respectively. Bland-Altman analysis was used to compare strain from the DIC and rosette (excluding 44% of trials with some evidence of strain rosette failure or debonding); the mean difference ± 2 standard deviations (SDs) was -108 με ± 702 με for the minimum (compressive) principal strain and -53 με ± 332 με for the maximum (tensile) principal strain. Although the DIC has higher noise, it avoids the relatively high risk we observed of strain gage debonding. These results can be used to develop guidelines for selecting a method to measure strain on bone. PMID:26902321

  15. Determining Micromechanical Strain in Nitinol

    SciTech Connect

    Strasberg, Matthew; /SLAC

    2006-09-27

    Nitinol is a superelastic alloy made of equal parts nickel and titanium. Due to its unique shape memory properties, nitinol is used to make medical stents, lifesaving devices used to allow blood flow in occluded arteries. Micromechanical models and even nitinol-specific finite element analysis (FEA) software are insufficient for unerringly predicting fatigue and resultant failure. Due to the sensitive nature of its application, a better understanding of nitinol on a granular scale is being pursued through X-ray diffraction techniques at the Stanford Synchrotron Radiation Laboratory (SSRL) at the Stanford Linear Accelerator Center (SLAC). Through analysis of powder diffraction patterns of nitinol under increasing tensile loads, localized strain can be calculated. We compare these results with micromechanical predictions in order to advance nitinol-relevant FEA tools. From this we hope to gain a greater understanding of how nitinol fatigues under multi-axial loads.

  16. Modeling competition between yeast strains

    NASA Astrophysics Data System (ADS)

    de Gee, Maarten; van Mourik, Hilda; de Visser, Arjan; Molenaar, Jaap

    2016-04-01

    We investigate toxin interference competition between S. cerevisiae colonies grown on a solid medium. In vivo experiments show that the outcome of this competition depends strongly on nutrient availability and cell densities. Here we present a new model for S. cerevisiae colonies, calculating the local height and composition of the colonies. The model simulates yeast colonies that show a good fit to experimental data. Simulations of colonies that start out with a homogeneous mixture of toxin producing and toxin sensitive cells can display remarkable pattern formation, depending on the initial ratio of the strains. Simulations in which the toxin producing and toxin sensitive species start at nearby positions clearly show that toxin production is advantageous.

  17. Fiber-optic polarimetric strain gauge

    NASA Astrophysics Data System (ADS)

    Bock, Wojtek J.; Wolinski, Tomasz R.

    A prototype fiber-optic polarimetric strain gauge based on the polarization mode coupling that occurs in highly birefringent optical fibers under the influence of axial strain is presented. Measurement set-up for a bonded strain gauge and its metrological characteristics are discussed together with the interpretation of observed physical effects in terms of changes in beat-length parameter under axial strain. The device is far more sensitive than conventional strain gauges, and can also be readily adjusted to a specified range of strain through an appropriate choice of fiber length and optical signal wavelength. The temperature drift of the device can be compensated in a straightforward procedure. The device is immune to electromagnetic interference, and is intrinsically safe in electrically dangerous, hazardous or explosive environments. Another attraction of this technology is its direct compatibility with fiber-optic telemetry, optical data transmission systems and multiplexing / demultiplexing technology.

  18. Sensor for Measuring Strain in Textile

    PubMed Central

    Mattmann, Corinne; Clemens, Frank; Tröster, Gerhard

    2008-01-01

    In this paper a stain sensor to measure large strain (80%) in textiles is presented. It consists of a mixture of 50wt-% thermoplastic elastomer (TPE) and 50wt-% carbon black particles and is fiber-shaped with a diameter of 0.315mm. The attachment of the sensor to the textile is realized using a silicone film. This sensor configuration was characterized using a strain tester and measuring the resistance (extension-retraction cycles): It showed a linear resistance response to strain, a small hysteresis, no ageing effects and a small dependance on the strain velocity. The total mean error caused by all these effects was ±5.5% in strain. Washing several times in a conventional washing machine did not influence the sensor properties. The paper finishes by showing an example application where 21 strain sensors were integrated into a catsuit. With this garment, 27 upper body postures could be recognized with an accuracy of 97%.

  19. An experimental evaluation of apparent strain from foil strain gauges attached to carbon composite substrates

    NASA Technical Reports Server (NTRS)

    Scott, B. R.; Lanius, S. J.; Auer, C. W.

    1987-01-01

    An experimental evaluation of apparent thermal strains is conducted using various combinations of substrate/gauge/attachment structure and redundant high temperature extensometry. It is found that the extensometry could either confirm independent measurements of the substrate's thermal expansion, or quantify nonzero mechanical strains resulting from uncertain material behavior and boundary conditions. Apparent strain and thermal expansion behavior data can then be used to modify the raw strain measurements in order to determine either stress producing or total strains. Limitation of the correction procedure for the three selected strain gauges is noted which is due to relatively large gauge/attachment variability.

  20. Mechanical strain and degradation of laser heterostructures

    NASA Astrophysics Data System (ADS)

    Ptashchenko, Alexander A.; Ptashchenko, Fedor A.; Maslejeva, Natalia V.; Sadova, Galina V.

    2001-02-01

    The effect of mechanical strain on degradation processes in GaAs-AlGaAs laser heterostructures (LHS) with stripe geometry and in light emitting diodes (LED) was experimentally studied. The strain was produced either by axial pressure or by indentation with a Wickers pyramid. We show that degradation affects the degree of polarization and the far-field distribution of laser emission. The effect of strain on the degradation intensity is estimated.

  1. Polyphasic characterization of xanthomonas strains from onion.

    PubMed

    Gent, David H; Schwartz, Howard F; Ishimaru, Carol A; Louws, Frank J; Cramer, Robert A; Lawrence, Christopher B

    2004-02-01

    ABSTRACT Xanthomonas leaf blight has become an increasingly important disease of onion, but the diversity among Xanthomonas strains isolated from onion is unknown, as is their relationship to other species and pathovars of Xanthomonas. Forty-nine Xanthomonas strains isolated from onion over 27 years from 10 diverse geographic regions were characterized by pathogenicity to onion and dry bean, fatty acid profiles, substrate utilization patterns (Biolog), bactericide resistance, repetitive sequence-based polymerase chain reaction fingerprinting, rDNA internally transcribed spacer (ITS) region, and hrp b6 gene sequencing. Multiplication of onion Xanthomonas strain R-O177 was not different from X. axonopodis pv. phaseoli in dry bean, but typical common bacterial blight disease symptoms were absent in dry bean. Populations from each geographical region were uniformly sensitive to 100 mug of CuSO(4), 100 mug of ZnSO(4), and 100 mug of streptomycin sulfate per ml. Biolog substrate utilization and fatty acid profiles revealed close phenoltypic relatedness between onion strains of Xanthomonas and X. axonopodis pv. dieffenbachiae (57% of strains) and X. arboricola pv. poinsettiicola (37% of strains), respectively. A logistic regression model based on fatty acid composition and substrate utilization classified 69% of strains into their geographical region of origin. Sequencing of a portion of the hrp B6 gene from 24 strains and ITS region from 25 strains revealed greater than 97% sequence similarity among strains. DNA fingerprinting revealed five genotype groups within onion strains of Xanthomonas and a high degree of genetic diversity among geographical regions of origin. Based on pathogenicity to onion, carbon substrate utilization, fatty acid profiles, rDNA genetic diversity, and genomic fingerprints, we conclude that the strains examined in this study are pathovar X. axonopodis pv. allii. Implications of genetic and phenotypic diversity within X. axonopodis pv. allii are

  2. AN ORGANOTYPIC UNIAXIAL STRAIN MODEL USING MICROFLUIDICS

    PubMed Central

    Dollé, Jean-Pierre; Morrison, Barclay; Schloss, Rene R.; Yarmush, Martin L.

    2012-01-01

    Traumatic brain injuries are the leading cause of disability each year in the US. The most common and devastating consequence is the stretching of axons caused by shear deformation that occurs during rotational acceleration of the brain during injury. The injury effects on axonal molecular and functional events are not fully characterized. We have developed a strain injury model that maintains the three dimensional cell architecture and neuronal networks found in vivo with the ability to visualize individual axons and their response to a mechanical injury. The advantage of this model is that it can apply uniaxial strains to axons that make functional connections between two organotypic slices and injury responses can be observed in real-time and over long term. This uniaxial strain model was designed to be capable of applying an array of mechanical strains at various rates of strain, thus replicating a range of modes of axonal injury. Long term culture, preservation of slice and cell orientation, and slice-slice connection on the device was demonstrated. The device has the ability to strain either individual axons or bundles of axons through the control of microchannel dimensions. The fidelity of the model was verified by observing characteristic responses to various strain injuries which included axonal beading, delayed elastic effects and breakdown in microtubules. Microtubule breakdown was shown to be dependent on the degree of the applied strain field, where maximal breakdown was observed at peak strain and minimal breakdown is observed at low strain. This strain injury model could be a powerful tool in assessing strain injury effects on functional axonal connections. PMID:23233120

  3. High strain rate damage of Carrara marble

    NASA Astrophysics Data System (ADS)

    Doan, Mai-Linh; Billi, Andrea

    2011-10-01

    Several cases of rock pulverization have been observed along major active faults in granite and other crystalline rocks. They have been interpreted as due to coseismic pervasive microfracturing. In contrast, little is known about pulverization in carbonates. With the aim of understanding carbonate pulverization, we investigate the high strain rate (c. 100 s-1) behavior of unconfined Carrara marble through a set of experiments with a Split Hopkinson Pressure Bar. Three final states were observed: (1) at low strain, the sample is kept intact, without apparent macrofractures; (2) failure is localized along a few fractures once stress is larger than 100 MPa, corresponding to a strain of 0.65%; (3) above 1.3% strain, the sample is pulverized. Contrary to granite, the transition to pulverization is controlled by strain rather than strain rate. Yet, at low strain rate, a sample from the same marble displayed only a few fractures. This suggests that the experiments were done above the strain rate transition to pulverization. Marble seems easier to pulverize than granite. This creates a paradox: finely pulverized rocks should be prevalent along any high strain zone near faults through carbonates, but this is not what is observed. A few alternatives are proposed to solve this paradox.

  4. Optical fiber sensor technique for strain measurement

    DOEpatents

    Butler, Michael A.; Ginley, David S.

    1989-01-01

    Laser light from a common source is split and conveyed through two similar optical fibers and emitted at their respective ends to form an interference pattern, one of the optical fibers having a portion thereof subjected to a strain. Changes in the strain cause changes in the optical path length of the strain fiber, and generate corresponding changes in the interference pattern. The interference pattern is received and transduced into signals representative of fringe shifts corresponding to changes in the strain experienced by the strained one of the optical fibers. These signals are then processed to evaluate strain as a function of time, typical examples of the application of the apparatus including electrodeposition of a metallic film on a conductive surface provided on the outside of the optical fiber being strained, so that strains generated in the optical fiber during the course of the electrodeposition are measurable as a function of time. In one aspect of the invention, signals relating to the fringe shift are stored for subsequent processing and analysis, whereas in another aspect of the invention the signals are processed for real-time display of the strain changes under study.

  5. Diversity among Streptomyces Strains Causing Potato Scab

    PubMed Central

    Doering-Saad, Christiane; Kämpfer, Peter; Manulis, Shulamit; Kritzman, Giora; Schneider, Jörg; Zakrzewska-Czerwinska, Jolanta; Schrempf, Hildgund; Barash, Isaac

    1992-01-01

    Eighty Streptomyces isolates, including 35 potato scab-inducing strains and 12 reference strains of Streptomyces scabies, were physiologically characterized by a total of 329 miniaturized tests. Overall similarities of all strains were determined by numerical taxonomy, with the unweighted average linkage (UPGMA) algorithm and simple matching (Ssm) and Jaccard (Sj) coefficients used as measures for similarity. Three cluster groups (A to C) were defined at a similarity level of 80.1% (Ssm); these groups contained 14 clusters and 24 unclustered strains defined at a similarity level of 86.5% (Ssm). Cluster group A contained strains phenotypically related to S. griseus or S. exfoliatus, whereas cluster group B contained strains which were phenotypically related to S. violaceus or S. rochei. The majority of the pathogenic isolates and reference strains were assigned to S. violaceus (57%) and S. griseus (22%). A DNA probe derived from the rRNA operon of S. coelicolor IMET 40271 was used to detect restriction fragment length polymorphisms (RELPs) among 40 pathogenic and nonpathogenic Streptomyces isolates. Southern blots revealed a high degree of diversity among the pathogenic strains tested. No significant correlation between numerical classification and RFLP grouping of Streptomyces strains could be revealed. The results obtained suggest that RFLP data are of minor importance in classification of Streptomyces species and that genes for pathogenicity determinants are spread among different Streptomyces species by mobilizable elements. Images PMID:16348823

  6. Distributed strain monitoring for bridges: temperature effects

    NASA Astrophysics Data System (ADS)

    Regier, Ryan; Hoult, Neil A.

    2014-03-01

    To better manage infrastructure assets as they reach the end of their service lives, quantitative data is required to better assess structural behavior and allow for more informed decision making. Distributed fiber optic strain sensors are one sensing technology that could provide comprehensive data for use in structural assessments as these systems potentially allow for strain to be measured with the same accuracy and gage lengths as conventional strain sensors. However, as with many sensor technologies, temperature can play an important role in terms of both the structure's and sensor's performance. To investigate this issue a fiber optic distributed strain sensor system was installed on a section of a two span reinforced concrete bridge on the TransCanada Highway. Strain data was acquired several times a day as well as over the course of several months to explore the effects of changing temperature on the data. The results show that the strain measurements are affected by the bridge behavior as a whole. The strain measurements due to temperature are compared to strain measurements that were taken during a load test on the bridge. The results show that even a small change in temperature can produce crack width and strain changes similar to those due to a fully loaded transport truck. Future directions for research in this area are outlined.

  7. Strain induced fragility transition in metallic glass

    PubMed Central

    Yu, Hai-Bin; Richert, Ranko; Maaß, Robert; Samwer, Konrad

    2015-01-01

    Relaxation dynamics are the central topic in glassy physics. Recently, there is an emerging view that mechanical strain plays a similar role as temperature in altering the relaxation dynamics. Here, we report that mechanical strain in a model metallic glass modulates the relaxation dynamics in unexpected ways. We find that a large strain amplitude makes a fragile liquid become stronger, reduces dynamical heterogeneity at the glass transition and broadens the loss spectra asymmetrically, in addition to speeding up the relaxation dynamics. These findings demonstrate the distinctive roles of strain compared with temperature on the relaxation dynamics and indicate that dynamical heterogeneity inherently relates to the fragility of glass-forming materials. PMID:25981888

  8. Measurement of Sorption-Induced Strain

    SciTech Connect

    Eric P. Robertson; Richard L. Christiansen

    2005-05-01

    Strain caused by the adsorption of gases was measured in samples of subbituminous coal from the Powder River basin of Wyoming, U.S.A. and high-volatile bituminous coal from east-central Utah, U.S.A. using an apparatus developed jointly at the Idaho National Laboratory (Idaho Falls, Idaho, U.S.A.) and Colorado School of Mines (Golden, Colorado, U.S.A.). The apparatus can be used to measure strain on multiple small coal samples based on the optical detection of the longitudinal strain instead of the more common usage of strain gauges, which require larger samples and longer equilibration times. With this apparatus, we showed that the swelling and shrinkage processes were reversible and that accurate strain data could be obtained in a shortened amount of time. A suite of strain curves was generated for these coals using gases that included carbon dioxide, nitrogen, methane, helium, and various mixtures of these gases. A Langmuir-type equation was applied to satisfactorily model the strain data obtained for pure gases. The sorption-induced strain measured in the subbituminous coal was larger than the high-volatile bituminous coal for all gases tested over the range of pressures used in the experimentation, with the CO2-induced strain for the subbituminous coal over twice as great at the bituminous coal.

  9. Lattice Strain Due to an Atomic Vacancy

    PubMed Central

    Li, Shidong; Sellers, Michael S.; Basaran, Cemal; Schultz, Andrew J.; Kofke, David A.

    2009-01-01

    Volumetric strain can be divided into two parts: strain due to bond distance change and strain due to vacancy sources and sinks. In this paper, efforts are focused on studying the atomic lattice strain due to a vacancy in an FCC metal lattice with molecular dynamics simulation (MDS). The result has been compared with that from a continuum mechanics method. It is shown that using a continuum mechanics approach yields constitutive results similar to the ones obtained based purely on molecular dynamics considerations. PMID:19582230

  10. Inflatable device for installing strain gage bridges

    NASA Technical Reports Server (NTRS)

    Cook, C. E.; Smith, G. E.; Monaghan, R. C. (Inventor)

    1983-01-01

    Methods and devices for installing in a tubular shaft multiple strain gages are disclosed with focus on a method and a device for pneumatically forcing strain gages into seated engagement with the internal surfaces of a tubular shaft in an installation of multiple strain gages in a tubular shaft. The strain gages or other electron devices are seated in a template-like component which is wrapped about a pneumatically expansible body. The component is inserted into a shaft and the body is pneumatically expanded after a suitable adhesive was applied to the surfaces.

  11. Acceleration and Velocity Sensing from Measured Strain

    NASA Technical Reports Server (NTRS)

    Pak, Chan-Gi; Truax, Roger

    2016-01-01

    A simple approach for computing acceleration and velocity of a structure from the strain is proposed in this study. First, deflection and slope of the structure are computed from the strain using a two-step theory. Frequencies of the structure are computed from the time histories of strain using a parameter estimation technique together with an Autoregressive Moving Average model. From deflection, slope, and frequencies of the structure, acceleration and velocity of the structure can be obtained using the proposed approach. shape sensing, fiber optic strain sensor, system equivalent reduction and expansion process.

  12. Predictions Of Fatigue Damage From Strain Histories

    NASA Technical Reports Server (NTRS)

    Sire, Robert A.; Besuner, Philip M.; Toomey, Tim

    1989-01-01

    Semiempirical mathematical model of fatigue damage in stressed objects uses experimental histories of strains in those objects to predict fatigue lives. Accounts for initiation and propagation of fatigue cracks on cycle-by-cycle basis. Measured strain history first digitized, then converted to history of turning-point strains for purposes of analysis. Data between turning points not used. When model calibrated against proper test data for each type of object characterized, its predictions of fatigue lives superior to statistical models as one based on root-mean-square strain.

  13. Strain accommodation in inelastic deformation of glasses

    NASA Astrophysics Data System (ADS)

    Murali, P.; Ramamurty, U.; Shenoy, Vijay B.

    2007-01-01

    Motivated by recent experiments on metallic glasses, we examine the micromechanisms of strain accommodation including crystallization and void formation during inelastic deformation of glasses by employing molecular statics simulations. Our atomistic simulations with Lennard-Jones-like potentials suggests that a softer short range interaction between atoms favors crystallization. Compressive hydrostatic strain in the presence of a shear strain promotes crystallization whereas a tensile hydrostatic strain is found to induce voids. The deformation subsequent to the onset of crystallization includes partial reamorphization and recrystallization, suggesting important atomistic mechanisms of plastic dissipation in glasses.

  14. Investigation of a noncontact strain measurement technique

    SciTech Connect

    Damiano, B.; Talarico, L.J.

    1996-05-01

    The goal of this project was to investigate the feasibility of a new noncontact technique for directly and continuously monitoring peak strain in rotating components. The technique utilizes the unique strain-sensitive magnetic material properties of transformation Induced Plasticity (TRIP) steel alloys to measure strain. These alloys are weakly magnetic when unstrained but become strongly ferromagnetic after mechanical deformation. A computer study was performed to determine whether the strain-induced change in the magnetic material properties of a TRIP steel gage bonded to a rotating component would cause significant perturbations in the magnetic flux of a stationary electromagnet. The effects of strain level, distance between the rotating component and the stationary electromagnet, and motion-induced eddy currents on flux perturbation magnitude were investigated. The calculated results indicate that a TRIP steel strain sensing element can cause a significant perturbation in the magnetic flux of a stationary electromagnet. The magnetic flux perturbation magnitude was found to be inversely proportional to the distance between the magnet face and the TRIP steel element and directly proportional to the TRIP steel strain level. The effect of motion-induced eddy currents on the magnetic flux was found to be negligible. It appears that the technique can be successfully applied to measure peak strain in rotating components; however, the sensitivity of the magnetic flux perturbation magnitude to the distance between the strain sensing element and the electromagnet may require making an independent proximity measurement.

  15. True stress-strain curves of cold worked stainless steel over a large range of strains

    NASA Astrophysics Data System (ADS)

    Kamaya, Masayuki; Kawakubo, Masahiro

    2014-08-01

    True stress-strain curves for cold worked stainless steel were obtained over a range of strains that included a large strain exceeding the strain for the tensile strength (post-necking strain). A specified testing method was used to obtain the stress-strain curves in air at room temperature. The testing method employed the digital image correlation (DIC) technique and iterative finite element analyses (FEA) and was referred to as IFD (Iteration FEA procedure based on DIC measurement) method. Although hourglass type specimens have been previously used for the IFD method, in this study, plate specimens with a parallel gage section were used to obtain accurate yield and tensile strengths together with the stress-strain curves. The stress-strain curves including the post-necking strain were successfully obtained by the IFD method, and it was shown that the stress-strain curves for different degrees of cold work collapsed onto a single curve when the offset strain was considered. It was also shown that the Swift type constitutive equation gave good regression for the true stress-strain curves including the post-necking strain regardless of the degree of cold work, although the Ramberg-Osgood type constitutive equation showed poor fit. In the regression for the Swift type constitutive equation, the constant for power law could be assumed to be nS = 0.5.

  16. Strain Rate Dependency of Coarse Crystal Marble Under Uniaxial Compression: Strength, Deformation and Strain Energy

    NASA Astrophysics Data System (ADS)

    Li, Yanrong; Huang, Da; Li, Xi'an

    2014-07-01

    Strain rate during testing, uniaxial or triaxial, has important influence on the measured mechanical properties of rocks. Uniaxial compression tests were performed at nine pre-specified static-to-quasistatic strain rates (ranging from 1 × 10-5 to 1 × 10-1 s-1) on coarse crystal marble. The aim is to gain deep insight into the influence of strain rate on characteristic stresses, deformation properties and conversion of strain energy of such rock. It is found that the strain rate of 5 × 10-3 s-1 is the threshold to delineate the failure modes the tested coarse marble behaves in. At a strain rate less than this threshold, single-plane shear and conjugate X-shaped shear are the main failure modes, while beyond this threshold, extensile and splitting failures are dominant. The stress for crack initiation, the critical stress for dilation, the peak stress, and Young's modulus are all found to increase with strain rate, with an exception that the above stresses and modulus appear relatively low compared to the strain rate in the range of between 1 × 10-4 and 5 × 10-3 s-1. The pre-peak absorbed strain energy, damage strain energy and elastic strain energy are found to increase with strain rate. In addition, the elastic strain energy stored before peak point favors brittle failure of the specimen, as the more stored elastic energy in the specimen, the stronger the fragmenting.

  17. Conduction band structure and electron mobility in uniaxially strained Si via externally applied strain in nanomembranes

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Euaruksakul, Chanan; Liu, Zheng; Himpsel, F. J.; Liu, Feng; Lagally, Max G.

    2011-08-01

    Strain changes the band structure of semiconductors. We use x-ray absorption spectroscopy to study the change in the density of conduction band (CB) states when silicon is uniaxially strained along the [1 0 0] and [1 1 0] directions. High stress can be applied to silicon nanomembranes, because their thinness allows high levels of strain without fracture. Strain-induced changes in both the sixfold degenerate Δ valleys and the eightfold degenerate L valleys are determined quantitatively. The uniaxial deformation potentials of both Δ and L valleys are directly extracted using a strain tensor appropriate to the boundary conditions, i.e., confinement in the plane in the direction orthogonal to the straining direction, which correspond to those of strained CMOS in commercial applications. The experimentally determined deformation potentials match the theoretical predictions well. We predict electron mobility enhancement created by strain-induced CB modifications.

  18. A comparison of eastern North American seismic strain-rates to glacial rebound strain-rates

    NASA Technical Reports Server (NTRS)

    James, Thomas S.; Bent, Allison L.

    1994-01-01

    Glacial rebound strain-rates computed using a simple Laurentide glacial loading model are of the order of 10(exp -9) per year within the region of glaciation and extending several hundred kilometers beyond. The horizontal strain-rates receive approximately equal contributions from horizontal and vertical velocities, a consequence of the spherical geometry adopted for the Earth model. In the eastern United States and southeastern Canada the computed strain-rates are 1-3 orders of magnitude greater than an estimate of the average seismic strain-rate (Anderson, 1986) and approximately 1 order of magnitude greater than predicted erosional strain-rates. The predicted glacial rebound strain-rates are not, in general, oriented in such a way as to augment the observed state of deviatoric stress, possibly explaining why the seismic strain-rates are much smaller than the glacial rebound strain-rates. An exception to this may be seismically active regions in the St. Lawrence valley.

  19. The Stress-Strain Condition Estimation of Detail in Crack Tip by Integral Strain Gauges

    NASA Astrophysics Data System (ADS)

    Syzrantsev, V.; Syzrantseva, K.

    2016-04-01

    The paper considers the task of stress-strain condition calculation of experimental sample in fatigue crack tip on weld boundary at its cyclic deforming. For this task decision authors use the information obtained by original means of cyclic strains measurement: Integral Strain Gauges. The results of carried experimental researches are compared with data of stress-strain condition estimation of detail in crack tip calculated by Finish Element Method.

  20. General Strain Theory and Delinquency: Focusing on the Influences of Key Strain Characteristics on Delinquency

    ERIC Educational Resources Information Center

    Moon, Byongook; Blurton, David; McCluskey, John D.

    2008-01-01

    The study examines the effects of recent, older, and chronic strains and of perceived injustice of strain on delinquency, sampling 777 Korean youth. Seven key strains most likely leading to delinquency, some of which were often overlooked in previous research, were included, and these are family conflict, parental punishment, teachers' punishment,…

  1. Silicon stress/strain activities at JPL

    NASA Technical Reports Server (NTRS)

    Chen, C. P.

    1986-01-01

    In-house Jet Propulsion Laboratory (JPL) work is described for silicon stress/strain, including the study of fracture mechanics, and on the high-temperature test program in which the low-strain response of silicon sheet materials above 1000 C is being measured and high temperature material property data are being determined.

  2. Nanocomposite Strain Gauges Having Small TCRs

    NASA Technical Reports Server (NTRS)

    Gregory, Otto; Chen, Ximing

    2009-01-01

    Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent strain. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic strain gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.

  3. Fiscal Strain in an Era of Retrenchment.

    ERIC Educational Resources Information Center

    Hentschke, Guilbert; Yagielski, John

    Preliminary results of a three-year study of fifteen school districts indicate that fiscal strain results from both "intended" and "unintended" factors. The authors construct a model of fiscal strain that combines budget constraints with school district decision-makers' preference functions and indifference curves. Using this model and 1976 and…

  4. High-Temperature Resistance Strain Gauges

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen

    1994-01-01

    Resistance strain gauges developed for use at high temperatures in demanding applications like testing aircraft engines and structures. Measures static strains at temperatures up to 800 degrees C. Small and highly reproducible. Readings corrected for temperature within small tolerances, provided temperatures measured simultaneously by thermocouples or other suitable devices. Connected in wheatstone bridge.

  5. Marital Role Strain and Sexual Satisfaction.

    ERIC Educational Resources Information Center

    Frank, Ellen; And Others

    1979-01-01

    Responses to a questionnaire pertaining to discrepancies between an individual's ideal and actual marital role behaviors and level of sexual satisfaction indicated lower levels of role strain in nonpatient couples. A higher level of role strain correlated with increased sexual dissatisfaction. (Author)

  6. Genome Annotation of Five Mycoplasma canis Strains

    PubMed Central

    May, M.; Michaels, D. L.; Barbet, A. F.

    2012-01-01

    To understand its potential to cause invasive disease, the genome of Mycoplasma canis strain PG14T from a dog's throat was compared to those of isolates from the genital tract or brain of dogs. The average nucleotide identity between strain pairs is 98%, and their genome annotations are similar. PMID:22815452

  7. Surfactin production by strains of Bacillus mojavensis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacillus mojavensis, RRC101 is an endophytic bacterium patented for control of fungal diseases in maize and other plants. DNA fingerprint analysis of the rep-PCR fragments of 35 B. mojavensis and 4 B. subtilis strains using the Diversilab genotyping system revealed genotypic distinctive strains alon...

  8. Medically Complex Home Care and Caregiver Strain

    ERIC Educational Resources Information Center

    Moorman, Sara M.; Macdonald, Cameron

    2013-01-01

    Purpose of the study: To examine (a) whether the content of caregiving tasks (i.e., nursing vs. personal care) contributes to variation in caregivers' strain and (b) whether the level of complexity of nursing tasks contributes to variation in strain among caregivers providing help with such tasks. Design and methods: The data came from the Cash…

  9. High strain rate behavior of polyurea compositions

    NASA Astrophysics Data System (ADS)

    Joshi, Vasant S.; Milby, Christopher

    2012-03-01

    High-strain-rate response of three polyurea compositions with varying molecular weights has been investigated using a Split Hopkinson Pressure Bar arrangement equipped with aluminum bars. Three polyurea compositions were synthesized from polyamines (Versalink, Air Products) with a multi-functional isocyanate (Isonate 143L, Dow Chemical). Amines with molecular weights of 1000, 650, and a blend of 250/1000 have been used in the current investigation. These materials have been tested to strain rates of over 6000/s. High strain rate results from these tests have shown varying trends as a function of increasing strain. While higher molecular weight composition show lower yield, they do not show dominant hardening behavior at lower strain. On the other hand, the blend of 250/1000 show higher load bearing capability but lower strain hardening effects than the 600 and 1000 molecular weight amine based materials. Results indicate that the initial increase in the modulus of the blend of 250/1000 may lead to the loss of strain hardening characteristics as the material is compressed to 50% strain, compared to 1000 molecular weight amine based material.

  10. Whole genome sequences of four Brucella strains.

    PubMed

    Ding, Jiabo; Pan, Yuanlong; Jiang, Hai; Cheng, Junsheng; Liu, Taotao; Qin, Nan; Yang, Yi; Cui, Buyun; Chen, Chen; Liu, Cuihua; Mao, Kairong; Zhu, Baoli

    2011-07-01

    Brucella melitensis and Brucella suis are intracellular pathogens of livestock and humans. Here we report four genome sequences, those of the virulent strain B. melitensis M28-12 and vaccine strains B. melitensis M5 and M111 and B. suis S2, which show different virulences and pathogenicities, which will help to design a more effective brucellosis vaccine. PMID:21602346

  11. Strain engineering in graphene by laser irradiation

    SciTech Connect

    Papasimakis, N.; Mailis, S.; Huang, C. C.; Al-Saab, F.; Hewak, D. W.; Luo, Z.; Shen, Z. X.

    2015-02-09

    We demonstrate that the Raman spectrum of graphene on lithium niobate can be controlled locally by continuous exposure to laser irradiation. We interpret our results in terms of changes to doping and mechanical strain and show that our observations are consistent with light-induced gradual strain relaxation in the graphene layer.

  12. Differentiation of Lactobacillus strains by ribotyping.

    PubMed Central

    Rodtong, S; Tannock, G W

    1993-01-01

    Fifty-four lactobacillus strains were differentiated by ribotyping. The stability of ribotypes characteristic of four strains of lactobacilli inhabiting the digestive tract of mice was investigated. One of four isolates of Lactobacillus delbrueckii GT21, which had been associated with mice for 22 months, had an altered ribotype. Images PMID:7504432

  13. Bicrystals with strain gradient effects

    SciTech Connect

    Shu, J.Y.

    1997-01-09

    Boundary between two perfectly bonded single crystals plays an important role in determining the deformation of the bicrystals. This work addresses the role of the grain boundary by considering the elevated hardening of a slip system due to a slip gradient. The slip gradients are associated with geometrically necessary dislocations and their effects become pronounced when a representative length scale of the deformation field is comparable to the dominant microstructural length scale of a material. A new rate-dependent crystal plasticity theory is presented and has been implemented within the finite element method framework. A planar bicrystal under uniform in-plane loading is studied using the new crystal theory. The strain is found to be continuous but nonuniform within a boundary layer around the interface. The lattice rotation is also nonuniform within the boundary layer. The width of the layer is determined by the misorientation of the grains, the hardening of slip systems, and most importantly by the characteristic material length scales. The overall yield strength of the bicrystal is also obtained. A significant grain-size dependence of the yield strength, the Hall- Petch effect is predicted.

  14. New naphthalene-degrading marine Pseudomonas strains.

    PubMed Central

    García-Valdés, E; Cozar, E; Rotger, R; Lalucat, J; Ursing, J

    1988-01-01

    Over 100 strains that utilized naphthalene as the only carbon and energy source were isolated from samples of marine sediments taken from a heavily polluted area. The isolates were characterized taxonomically and physiologically. Most of these strains belonged to the genus Pseudomonas, and seven of them did not fit any previous taxonomic description. They differed from type strains in a few biochemical characteristics and in the utilization of aromatic compounds. None had catechol 1,2-dioxygenase activity, and catechol 2,3-dioxygenase was responsible for the aromatic ring cleavage. DNA hybridization demonstrated a close relationship between two isolates and the Pseudomonas stutzeri type strain, and between five isolates and the Pseudomonas testosteroni type strain. On the basis of nutritional and enzymatic characteristics, it was assumed that the seven isolates represent new biovars belonging to the species P. testosteroni and P. stutzeri that are able to degrade aromatic hydrocarbons. Images PMID:3202629

  15. New naphthalene-degrading marine Pseudomonas strains

    SciTech Connect

    Garcia-Valdes, E.; Cozar, E.; Rotger, R. Lalucat, J. ); Ursing, J. )

    1988-10-01

    Over 100 strains that utilized naphthalene as the only carbon and energy source were isolated from samples of marine sediments taken from a heavily polluted area. The isolates were characterized taxonomically and physiologically. Most of these strains belonged to the genus Pseudomonas, and seven of them did not fit any previous taxonomic description. They differed from type strains in a few biochemical characteristics and in the utilization of aromatic compounds. None had catechol 1,2-dioxygenase activity, and catechol 2,3-dioxygenase was responsible for the aromatic ring cleavage. DNA hybridizations demonstrated a close relationship between two isolates and the Pseudomonas stutzeri type strain, and between five isolates and the Pseudomonas testosteroni type strain. On the basis of nutritional and enzymatic characteristics, it was assumed that the seven isolates represent new biovars belonging to the species P. testosteroni and P. stutzeri that are able to degrade aromatic hydrocarbons.

  16. Nanoscale strain mapping in battery nanostructures

    SciTech Connect

    Ulvestad, A. Kim, J. W.; Dietze, S. H.; Shpyrko, O. G.; Cho, H. M.; Meng, Y. S.; Harder, R.; Fohtung, E.

    2014-02-17

    Coherent x-ray diffraction imaging is used to map the local three dimensional strain inhomogeneity and electron density distribution of two individual LiNi{sub 0.5}Mn{sub 1.5}O{sub 4−δ} cathode nanoparticles in both ex-situ and in-situ environments. Our reconstructed images revealed a maximum strain of 0.4%. We observed different variations in strain inhomogeneity due to multiple competing effects. The compressive/tensile component of the strain is connected to the local lithium content and, on the surface, interpreted in terms of a local Jahn-Teller distortion of Mn{sup 3+}. Finally, the measured strain distributions are discussed in terms of their impact on competing theoretical models of the lithiation process.

  17. Mechanical strain effects on black phosphorus nanoresonators.

    PubMed

    Wang, Cui-Xia; Zhang, Chao; Jiang, Jin-Wu; Park, Harold S; Rabczuk, Timon

    2016-01-14

    We perform classical molecular dynamics simulations to investigate the effects of mechanical strain on single-layer black phosphorus nanoresonators at different temperatures. We find that the resonant frequency is highly anisotropic in black phosphorus due to its intrinsic puckered configuration, and that the quality factor in the armchair direction is higher than in the zigzag direction at room temperature. The quality factors are also found to be intrinsically larger than those in graphene and MoS2 nanoresonators. The quality factors can be increased by more than a factor of two by applying tensile strain, with uniaxial strain in the armchair direction being the most effective. However, there is an upper bound for the quality factor increase due to nonlinear effects at large strains, after which the quality factor decreases. The tension induced nonlinear effect is stronger along the zigzag direction, resulting in a smaller maximum strain for quality factor enhancement. PMID:26649476

  18. Human prion strain selection in transgenic mice

    PubMed Central

    Giles, Kurt; Glidden, David V.; Patel, Smita; Korth, Carsten; Groth, Darlene; Lemus, Azucena; DeArmond, Stephen J.; Prusiner, Stanley B.

    2010-01-01

    Transgenic (Tg) mice expressing chimeras of mouse and human prion proteins (PrP) have shorter incubation periods for Creutzfeldt-Jakob disease (CJD) prions than mice expressing full-length human PrP. Increasing the sequence similarity of the chimeric PrP to mouse PrP, by reverting human residues to mouse, resulted in a Tg line, denoted Tg22372, which was susceptible to sporadic (s) CJD prions in ~110 days 1. Reversion of one additional residue (M111V) resulted in a new Tg line, termed Tg1014, susceptible to sCJD prions in ~75 days. Tg1014 mice also has shorter incubation periods for variant (v) CJD prions, providing a more tractable model for studying this prion strain. Transmission of vCJD prions to Tg1014 mice resulted in two different strains, determined by neuropathology and biochemical analysis, which correlated with the length of the incubation time. One strain had the biochemical, neuropathological, and transmission characteristics including longer incubation times of the inoculated vCJD strain; the second strain produced a phenotype resembling that of sCJD prions including relatively shorter incubation periods. Mice with intermediate incubation periods for vCJD prions had a mixture of the two strains. Both strains were serially transmitted in Tg1014 mice, which led to further reduction in incubation periods. Conversion of vCJD-like to sCJD-like strains was favored in Tg1014 mice more than in the Tg22372 line. The single amino acid difference therefore appears to offer selective pressure for propagation of the sCJD-like strain. These two Tg mouse lines provide relatively rapid models to study human prion diseases as well as the evolution of human prion strains. PMID:20695008

  19. Micro-scale strain mapping technique: a tool to quantify strain partitioning during creep deformation

    NASA Astrophysics Data System (ADS)

    Quintanilla-Terminel, Alejandra; Zimmerman, Mark; Evans, Brian; Kohlstedt, David

    2016-04-01

    Several deformation mechanisms interact to accommodate plastic deformation. Quantifying the contribution of each to the total strain is necessary for establishing a better link between observed microstructures and mechanical data, as well as to allow more confident extrapolation from laboratory to natural conditions. In this contribution, we present the experimental and computational technique involved in micro-scale strain mapping (MSSM). The MSSM technique relies on analyzing the relative displacement of initially regularly spaced markers after deformation. We present several microfabrication techniques that permit us to pattern various rocks with micrometric and nanometric metal markers, as well as the challenges faced in working at high temperatures and pressures. A Hough transform algorithm was used to detect the markers and automate as much as possible the strain analysis. The von Mises strain is calculated for a set of n-points and their relative displacements, which allow us to map the strain at different length scales. We applied the MSSM technique to study strain partitioning during deformation creep of Carrara marble and San Carlos olivine at a confining pressure, Pc, of 300 MPa and homologous temperatures of 0.3 to 0.6. We measured the local strain and strain heterogeneity produced during creep deformation of split cylinders of Carrara marble under conventional triaxial loading to inelastic strains of 11 to 36% at a strain rate of 3x10‑5s‑1, Pc = 300 MPa and 400o < T <700oC. We conclude that the evolution of deformation structures in marble takes place over a substantial interval in strain and that the duration of this interval depends on strain rate, temperature, and pressure. Our first results on strain mapping of olivine deformed at T = 1150oC and Pc = 300 MPa demonstrate promise for characterizing intragranular strain and better defining the contribution of grain boundary sliding to the total strain.

  20. Nonlinear stress-strain behavior of carbon nanotube fibers subject to slow sustained strain rate

    NASA Astrophysics Data System (ADS)

    Sun, Gengzhi; Wang, Dong; Pang, John H. L.; Liu, Jun; Zheng, Lianxi

    2013-09-01

    Nonlinear stress-strain behavior of carbon nanotube (CNT) fibers is studied based on the test data where fiber strength can be modeled by the Weibull distribution. CNT fibers spun from vertically aligned arrays are tensioned at slow sustained strain rate (0.00001 1/s) to study the tensile strength resulting from sliding-to-failure effects. A model is developed to estimate the Weibull modulus which characterizes the dispersion of fiber strengths in terms of the maximum sustained stress and failure strain of the fibers. The results show that the sliding indeed has great influence on the stress-strain relation of CNT fibers at low strain rate.

  1. Strain relaxation in buried strained layers by mixture of single and dipolar dislocation arrays

    NASA Astrophysics Data System (ADS)

    Jin, Z.; Yang, S.; Ma, C.; Liu, S.

    1999-06-01

    The strain relaxation in buried strained layers is investigated using an elastic continuum model. The mixture of single dislocations residing at the substrate/strained layer interface (lower interface) and dipolar dislocations in which one is at the lower interface and the other at the strained layer/capping layer interface (upper interface), is proposed. In the mixture, the dislocation distributions are denoted by a parameter which is the ratio of the density of misfit dislocations at the upper interface to that at the lower interface. In a buried strained layer, relaxation of mean strain occurs by introduction of two orthogonal arrays of mixture of single and dipolar dislocations. Considering both the free surface and interactions between dislocations, the total elastic energy per unit area of buried strained layer containing two orthogonal arrays of mixture of single and dipolar dislocations is calculated. The energy is dependent on the misfit dislocation distributions. On energy minimization considerations, the expression of the misfit dislocation distributions in a buried strained layer with arbitrary strain relaxation and capping layer thickness is derived. It is demonstrated that the strain is initially relaxed by the single misfit dislocations and relaxed by the mixture of single and dipolar misfit dislocations in the final stage of strain relaxation in many buried layers of practical interest.

  2. In vitro strain measurement in the porcine antrum using ultrasound doppler strain rate imaging.

    PubMed

    Ahmed, Aymen Bushra; Gilja, Odd Helge; Gregersen, Hans; Ødegaard, Svein; Matre, Knut

    2006-04-01

    Strain rate imaging (SRI) enables study of deformation in soft tissues. The aim of this study was to evaluate the accuracy of SRI in measuring strain in the porcine antral wall in vitro. An experimental set-up enabled controlled distension of a porcine stomach in a saline reservoir. Radial strain obtained by SRI was compared with radial strain calculated from B-mode ultrasonography. Circumferential strain obtained by SRI was compared with circumferential strain calculated from sonomicrometry. The agreement between radial strain values measured by SRI and B-mode, along and across several ultrasound (US) beams, using US frequency 6.7 MHz and strain length (SL) = 1.9 mm was = -1.0 +/- 12.1% and 0.5 +/- 13.4%, respectively (mean difference +/- 2SD%) and it was better than with SL 1.2 mm. Compared with sonomicrometry, SRI-determined circumferential strain using 6.7 MHz and SL = 1.9 mm was less accurate, whether averaging along or across several US beams (-9.2 +/- 46.7% and 13.8 +/- 51.2%, respectively). In conclusion, SRI gave accurate measurement of radial strain of the antral wall, but seemed to be less accurate for measurement of circumferential strain for this in vitro set-up. PMID:16616598

  3. Amerindian Helicobacter pylori Strains Go Extinct, as European Strains Expand Their Host Range

    PubMed Central

    Domínguez-Bello, Maria G.; Pérez, Maria E.; Bortolini, Maria C.; Salzano, Francisco M.; Pericchi, Luis R.; Zambrano-Guzmán, Orlisbeth; Linz, Bodo

    2008-01-01

    We studied the diversity of bacteria and host in the H. pylori-human model. The human indigenous bacterium H. pylori diverged along with humans, into African, European, Asian and Amerindian groups. Of these, Amerindians have the least genetic diversity. Since niche diversity widens the sets of resources for colonizing species, we predicted that the Amerindian H. pylori strains would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes) of 131 strains: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all strains that had been cultured from Africans were African strains (hpAfrica1), all from Spanish were European (hpEurope) and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori strains were hspAmerind. Strains hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination). The lower genetic structure in hpEurope strains is consistent with colonization of a diversity of hosts. If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear. This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts. PMID:18830403

  4. Fabrication and device characteristics of strained-Si-on-insulator (strained-SOI) CMOS

    NASA Astrophysics Data System (ADS)

    Takagi, Shin-ichi; Mizuno, Tomohisa; Tezuka, Tsutomu; Sugiyama, Naoharu; Numata, Toshinori; Usuda, Koji; Moriyama, Yoshihiko; Nakaharai, Shu; Koga, Junji; Tanabe, Akihito; Maeda, Tatsuro

    2004-03-01

    Strained-Si-on-insulator (strained-SOI) CMOS is a promising device structure for satisfying requirements of both high current drive and low supply voltage under sub-100 nm nodes, because of the combination of advantages of SOI MOSFETs and high mobility strained-Si channels. In this paper, we present the concept, the device structures and the fabrication techniques of strained-SOI CMOS. We introduce our original fabrication method of strained-SOI substrates, called the Ge condensation technique. It is experimentally shown that strained-SOI CMOS has higher electron and hole mobility and that strained-SOI CMOS ring oscillators successfully operate with the performance enhancement of 30-70% against conventional SOI CMOS ones.

  5. Highly Invasive Listeria monocytogenes Strains Have Growth and Invasion Advantages in Strain Competition

    PubMed Central

    Manthou, Evanthia; Ciolacu, Luminita; Wagner, Martin; Skandamis, Panagiotis N.

    2015-01-01

    Multiple Listeria monocytogenes strains can be present in the same food sample; moreover, infection with more than one L. monocytogenes strain can also occur. In this study we investigated the impact of strain competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor strains, whose growth was not (or only slightly) influenced by the presence of other strains and two weak competitor strains, which were outcompeted by other strains. Cell contact was essential for growth inhibition. In vitro virulence assays using human intestinal epithelial Caco2 cells showed a correlation between the invasion efficiency and growth inhibition: the strong growth competitor strains showed high invasiveness. Moreover, invasion efficiency of the highly invasive strain was further increased in certain combinations by the presence of a low invasive strain. In all tested combinations, the less invasive strain was outcompeted by the higher invasive strain. Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell. In conclusion, we show that growth of L. monocytogenes can be inhibited by strains of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes strain in food can lead to increased infection rates due to synergistic effects on the virulence potential. PMID:26529510

  6. Volume strain within The Geysers geothermal field

    NASA Astrophysics Data System (ADS)

    Mossop, Antony; Segall, Paul

    1999-12-01

    During the 1970s and 1980s, The Geysers geothermal region was rapidly developed as a site of geothermal power production. The likelihood that this could cause significant strain within the reservoir, with corresponding surface displacements, led to a series of deformation monitoring surveys. In 1973, 1975, 1977, and 1980, The Geysers region was surveyed using first-order, class I, spirit leveling. In 1994, 1995, and 1996, many of the leveling control monuments were resurveyed using high-precision Global Positioning System receivers. The two survey methods are reconciled using the GEOID96 geoid model. The displacements are inverted to determine volume strain within the reservoir. For the period 1980-1994, peak volume strains in excess of 5×10-4 are imaged. There is an excellent correlation between the observed changes in reservoir steam pressures and the imaged volume strain. If reservoir pressure changes are inducing volume strain, then the reservoir quasi-static bulk modulus K must be <4.6×109 Pa. However, seismic velocities indicate a much suffer reservoir with K = 3.4 × 1010 Pa. This apparent discrepancy is shown to be consistent with predicted frequency dependence in K for fractured and water-saturated rock. Inversion of surface deformation data therefore appears to be a powerful method for imaging pressure change within the body of the reservoir. Correlation between induced seismicity at The Geysers and volume strain is observed. However, earthquake distribution does not appear to have a simple relationship with volume strain rate.

  7. Strain engineering of graphene: a review.

    PubMed

    Si, Chen; Sun, Zhimei; Liu, Feng

    2016-02-14

    Graphene has intrigued the science community by many unique properties not found in conventional materials. In particular, it is the strongest two-dimensional material ever measured, being able to sustain reversible tensile elastic strain larger than 20%, which yields an interesting possibility to tune the properties of graphene by strain and thus opens a new field called "straintronics". In this article, the current progress in the strain engineering of graphene is reviewed. We first summarize the strain effects on the electronic structure and Raman spectra of graphene. We then highlight the electron-phonon coupling greatly enhanced by the biaxial strain and the strong pseudomagnetic field induced by the non-uniform strain with specific distribution. Finally, the potential application of strain-engineering in the self-assembly of foreign atoms on the graphene surface is also discussed. Given the short history of graphene straintronics research, the current progress has been notable, and many further advances in this field are expected. PMID:26796960

  8. Strain mapping analysis of textile composites

    NASA Astrophysics Data System (ADS)

    Ivanov, Dmitry; Ivanov, Sergey; Lomov, Stepan; Verpoest, Ignaas

    2009-03-01

    The focus of the work is meso-scale analysis (scale level of the fabric unit cell) of textile composite deformation and failure. The surface strain measurement is used for: (1) experimental investigation, which includes study of strain distribution at various stages of deformation, plasticity detection, damage initiation; (2) numerical validation of the correspondent finite element (FE) models. Two examples are considered: carbon-epoxy triaxial-braided and glass polypropylene-woven composite. The surface strain measurement (by digital image correlation technique) accompanies the tensile tests, aiming at: (1) elastic anisotropic constants characterisation, (2) study of non-linear material behaviour (for the thermoplastic composite), (3) control of homogeneity of the macro-strain distribution, and (4) analysis of damage initiation in brittle composites. Validation of meso-FE models by strain measurements encounters difficulties arising from (1) resolution of the strain measurements, (2) irregularities of the initial structure such as random layer nesting, ply interaction, and deviation of yarns from their theoretical position, which affects the measured strain fields. The paper discusses these difficulties and demonstrates a qualitative agreement with the FE analysis of idealised composite configurations.

  9. Biological characterization of Trypanosoma cruzi strains.

    PubMed

    Martínez-Díaz, R A; Escario, J A; Nogal-Ruiz, J J; Gómez-Barrio, A

    2001-01-01

    Biological parameters of five Trypanosoma cruzi strains from different sources were determined in order to know the laboratory behaviour of natural populations. The parameters evaluated were growth kinetics of epimastigotes, differentiation into metacyclic forms, infectivity in mammalian cells grown in vitro and parasite susceptibility to nifurtimox, benznidazole and gentian violet. Differences in transformation to metacyclic, in the percentage of infected cells as well as in the number of amastigotes per cell were observed among the strains. Regarding to pharmacological assays, Y strain was the most sensitive to the three assayed compounds. These data demonstrate the heterogeneity of natural populations of T. cruzi, the only responsible of infection in humans. PMID:11285475

  10. Electrical measurements as stress-strain monitors

    USGS Publications Warehouse

    Madden, T. R.

    1979-01-01

    Many of the measurements of phyiscal properties being made in earthquake prediction studies are based on the premise that these properties are influenced by stresses and strains, especially so near the failure point. Electrical properties of rocks are controlled by the fluid in the pores and cracks in the rocks. Because these regions are most influenced by stresses, one should expect electrical measurements to be sensitive measures of changing stresses and strains. Nevertheless, the strain changes we are dealing with are very small, and, consequently, we need very sensitive instruments to detect them.  

  11. Dark field electron holography for strain measurement.

    PubMed

    Béché, A; Rouvière, J L; Barnes, J P; Cooper, D

    2011-02-01

    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. PMID:21333860

  12. Strain Determination Using Electron Backscatter Diffraction

    SciTech Connect

    Krause, M.; Graff, A.; Altmann, F.

    2010-11-24

    In the present paper we demonstrate the use of electron backscatter diffraction (EBSD) for high resolution elastic strain determination. Here, we focus on analysis methods based on determination of small shifts in EBSD pattern with respect to a reference pattern using cross-correlation algorithms. Additionally we highlight the excellent spatial and depth resolution of EBSD and introduce the use of simulated diffraction patterns based on dynamical diffraction theory for sensitivity estimation. Moreover the potential of EBSD for strain analysis of strained thin films with particular emphasis on appropriate target preparation which respect to occurring lattice defects is demonstrated.

  13. Transport in Strained Graphene at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Aguilera-Servin, Juan; Nosek, Adrian; Pan, Cheng; Bockrath, Marc

    2015-03-01

    Strain in graphene layers produces synthetic gauge fields that may be used to modify the properties of its electron system. We study single layers of graphene transferred over Ti/Au electrical contacts on oxidized Si wafers with etched triangular holes in the oxide. The layers are strained by applying pressure electrostatically using a gate voltage and hydrostatically using an external inert gas. We investigate electronic transport in this suspended variable-strain graphene system at low temperatures. We will discuss our latest results.

  14. Strain gage balances and buffet gages

    NASA Technical Reports Server (NTRS)

    Ferris, A. T.

    1983-01-01

    One-piece strain gage force balances were developed for use in the National Transonic Facility (NTF). This was accomplished by studying the effects of the cryogenic environment on materials, strain gages, cements, solders, and moisture proofing agents, and selecting those that minimized strain gage output changes due to temperature. In addition, because of the higher loads that may be imposed by the NTF, these balances are designed to carry a larger load for a given diameter than conventional balances. Full cryogenic calibrations were accomplished, and wind tunnel results that were obtained from the Langley 0-3-Meter Transonic Cryogenic Tunnel were used to verify laboratory test results.

  15. Microstructural Analysis of Welding: Deformation and Strain

    NASA Astrophysics Data System (ADS)

    Quane, S. L.; Russell, K.

    2003-12-01

    Welding in pyroclastic deposits involves the sintering, compaction and flattening of hot glassy particles and is attended by systematic changes in physical properties. Welded materials contain implicit information regarding the total accumulated strain as well as the mechanisms of deformation. Here, we use detailed microstructural analysis of synthetic and natural welded materials to make quantitative estimates of strain and constrain the rheology of these materials during the welding process. Part one of our study comprises microstructural analysis of end products from unconfined high temperature deformation experiments on sintered cores of soda-lime silica glass spheres. This analogue material has relatively simple and well-characterized starting properties. Furthermore, the initially spherical shapes of particles provide excellent strain markers. Experiments were run at a variety of temperatures, strain rates and stresses resulting in end products with varying degrees of total strain. The nature of strain partitioning and accumulation are evaluated using image analysis techniques on scanned images and photomicrographs of thin sections cut perpendicular to the loading direction of each experimental product. Shapes of the individual deformed particles (e.g., oblate spheroids) were determined and the Scion image analysis program was used to create a best-fit ellipse for each particle. Statistics collected on each particle include: axial dimension (a), vertical dimension (c) and angle from the horizontal. The data are used to calculate the oblateness of each particle (1-c/a) and the angle of deformation induced foliation. Furthermore, the relative proportions of visible blue epoxy in the sample scans determine bulk porosity. The average oblateness of the particles is a direct, independent measure of the accumulated strain in each sample. Results indicate that these measured values are equal to calculated theoretical values of oblateness for spheroids undergoing the

  16. Freeze-drying Various Strains of Shigella

    PubMed Central

    Berman, Sanford; Altieri, Patricia L.; Groffinger, Albert; Lowenthal, Joseph P.; Formal, Samuel B.

    1968-01-01

    Of six candidate strains of Shigella prepared in Brain Heart Infusion broth as freeze-dried vaccine, low survival rates were obtained with two of the most promising strains. Survival rates with these two strains were increased to acceptable levels when the organisms were suspended in a medium consisting of 8.2% sucrose, 0.01 M phosphate, 0.07% monosodium glutamate, and 2.5% human serum albumin. Alteration of the freezing temperature did not improve the recovery rates significantly. PMID:5726151

  17. A study of the effect of apparent strain on thermal stress measurement for two types of elevated temperature strain gages

    NASA Technical Reports Server (NTRS)

    Jenkins, J. M.

    1983-01-01

    A weldable type strain gage was used to measure low level thermal stress in an elevated temperature environment. Foil strain gages used in a comparative manner reveal that the apparent strain of weldable strain gages is not sufficiently known to acquire accurate low level thermal stress data. Apparent strain data acquired from coupon tests reveals a large scatter in apparent strain characteristics among the weldable strain gages. It is concluded that apparent strain data for individual weldable strain gages must be required prior to installation if valid thermal stress data is to be obtained through the temperature range of room temperature to 755 K (900 F).

  18. 40 CFR 180.1209 - Bacillus subtilis strain QST 713 and strain QST 713 variant soil; exemption from the requirement...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... strain QST 713 variant soil; exemption from the requirement of a tolerance. 180.1209 Section 180.1209... strain QST 713 and strain QST 713 variant soil; exemption from the requirement of a tolerance. An... Bacillus subtilis strain QST 713 and strain QST 713 variant soil when used in or on all food commodities....

  19. 40 CFR 180.1209 - Bacillus subtilis strain QST 713 and strain QST 713 variant soil; exemption from the requirement...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... strain QST 713 variant soil; exemption from the requirement of a tolerance. 180.1209 Section 180.1209... strain QST 713 and strain QST 713 variant soil; exemption from the requirement of a tolerance. An... Bacillus subtilis strain QST 713 and strain QST 713 variant soil when used in or on all food commodities....

  20. A new radial strain and strain rate estimation method using autocorrelation for carotid artery

    NASA Astrophysics Data System (ADS)

    Ye, Jihui; Kim, Hoonmin; Park, Jongho; Yeo, Sunmi; Shim, Hwan; Lim, Hyungjoon; Yoo, Yangmo

    2014-03-01

    Atherosclerosis is a leading cause of cardiovascular disease. The early diagnosis of atherosclerosis is of clinical interest since it can prevent any adverse effects of atherosclerotic vascular diseases. In this paper, a new carotid artery radial strain estimation method based on autocorrelation is presented. In the proposed method, the strain is first estimated by the autocorrelation of two complex signals from the consecutive frames. Then, the angular phase from autocorrelation is converted to strain and strain rate and they are analyzed over time. In addition, a 2D strain image over region of interest in a carotid artery can be displayed. To evaluate the feasibility of the proposed radial strain estimation method, radiofrequency (RF) data of 408 frames in the carotid artery of a volunteer were acquired by a commercial ultrasound system equipped with a research package (V10, Samsung Medison, Korea) by using a L5-13IS linear array transducer. From in vivo carotid artery data, the mean strain estimate was -0.1372 while its minimum and maximum values were -2.961 and 0.909, respectively. Moreover, the overall strain estimates are highly correlated with the reconstructed M-mode trace. Similar results were obtained from the estimation of the strain rate change over time. These results indicate that the proposed carotid artery radial strain estimation method is useful for assessing the arterial wall's stiffness noninvasively without increasing the computational complexity.

  1. Tropical Strains of Ralstonia solanacearum Outcompete Race 3 Biovar 2 Strains at Lowland Tropical Temperatures

    PubMed Central

    Huerta, Alejandra I.; Milling, Annett

    2015-01-01

    Bacterial wilt, caused by members of the heterogenous Ralstonia solanacearum species complex, is an economically important vascular disease affecting many crops. Human activity has widely disseminated R. solanacearum strains, increasing their global agricultural impact. However, tropical highland race 3 biovar 2 (R3bv2) strains do not cause disease in tropical lowlands, even though they are virulent at warm temperatures. We tested the hypothesis that differences in temperature adaptation and competitive fitness explain the uneven geographic distribution of R. solanacearum strains. Using three phylogenetically and ecologically distinct strains, we measured competitive fitness at two temperatures following paired-strain inoculations of their shared host, tomato. Lowland tropical strain GMI1000 was only weakly virulent on tomato under temperate conditions (24°C for day and 19°C for night [24/19°C]), but highland tropical R3bv2 strain UW551 and U.S. warm temperate strain K60 were highly virulent at both 24/19°C and 28°C. Strain K60 was significantly more competitive than both GMI1000 and UW551 in tomato rhizospheres and stems at 28°C, and GMI1000 also outcompeted UW551 at 28°C. The results were reversed at cooler temperatures, at which highland strain UW551 generally outcompeted GMI1000 and K60 in planta. The superior competitive index of UW551 at 24/19°C suggests that adaptation to cool temperatures could explain why only R3bv2 strains threaten highland agriculture. Strains K60 and GMI1000 each produced different bacteriocins that inhibited growth of UW551 in culture. Such interstrain inhibition could explain why R3bv2 strains do not cause disease in tropical lowlands. PMID:25769835

  2. Clostridium thermosaccharolyticum strain deficient in acetate production

    SciTech Connect

    Rothstein, D.M.

    1986-01-01

    A mutant of Clostridium thermosaccharolyticum that is blocked in acetate production was isolated after treatment with nitrosoguanidine and selection for fluoroacetate resistance. The mutant produced more ethanol than the parent strain did.

  3. High Strain Rate Rheology of Polymer Melts

    NASA Astrophysics Data System (ADS)

    Kelly, Adrian; Gough, Tim; Whiteside, Ben; Coates, Phil D.

    2009-07-01

    A modified servo electric injection moulding machine has been used in air-shot mode with capillary dies fitted at the nozzle to examine the rheology of a number of commercial polymers at wall shear strain rates of up to 107 s-1. Shear and extensional flow properties were obtained through the use of long and orifice (close to zero land length) dies of the same diameter. A range of polyethylene, polypropylene and polystyrene melts have been characterized; good agreement was found between the three techniques used in the ranges where strain rates overlapped. Shear viscosity of the polymers studied was found to exhibit a plateau above approximately 1×106 s-1. A relationship between the measured high strain rate rheological behaviour and molecular structure was noted, with polymers containing larger side groups reaching the rate independent plateau at lower strain rates than those with simpler structures.

  4. Strained Hydrocarbons as Potential Hypergolic Fuels

    NASA Technical Reports Server (NTRS)

    2005-01-01

    A storable combination of high-energy hypergolic fuel and oxidizer is advantageous to the future of reusable launch vehicles (RLVs). The combination will allow an increase in energy per unit volume of fuel and eliminate the need for an external ignition system. Strained systems have been studied as potential high-density fuels. Adding hypergolic functional groups, such as amino groups, to these hydrocarbons will potentially allow auto ignition of strained systems with hydrogen peroxide. Several straight chain amines and their strained counterparts containing an equivalent number of carbon atoms have been purchased and synthesized. These amines provide initial studies to determine the effects of fuel vapor pressure, strain energy, fuel miscibility, and amine substitution upon fuel ignition time and hypergolicity with hydrogen peroxide as an oxidizer.

  5. Strain accumulation along the Cascadia Subduction Zone

    NASA Astrophysics Data System (ADS)

    Murray, Mark H.; Lisowski, Michael

    2000-11-01

    We combine triangulation, trilateration, and GPS observations to determine horizontal strain rates along the Cascadia subduction zone from Cape Mendocino to the Strait of Juan de Fuca. Shear-strain rates are significantly greater than zero (95% confidence) in all forearc regions (26-167 nanoradians/yr), and are not significant in the arc and backarc regions. The deformation is primarily uniaxial contraction nearly parallel to Juan de Fuca-North America plate convergence (N55°-80°E). The strain rates are consistent with an elastic dislocation model for interseismic slip with a shallow 100-km wide locked zone and a deeper 75-km transition zone along the entire megathrust, except along the central Oregon coast where relatively lower strain rates are consistent with 30-40 km wide locked and transition zones.

  6. Tuning strain in flexible graphene nanoelectromechanical resonators

    NASA Astrophysics Data System (ADS)

    Guan, Fen; Kumaravadivel, Piranavan; Averin, Dmitri V.; Du, Xu

    2015-11-01

    The structural flexibility of low dimensional nanomaterials offers unique opportunities for studying the impact of strain on their physical properties and for developing innovative devices utilizing strain engineering. A key towards such goals is a device platform which allows the independent tuning and reliable calibration of the strain. Here, we report the fabrication and characterization of graphene nanoelectromechanical resonators (GNEMRs) on flexible substrates. Combining substrate bending and electrostatic gating, we achieve the independent tuning of the strain and sagging in graphene and explore the nonlinear dynamics over a wide parameter space. Analytical and numerical studies of a continuum mechanics model, including the competing higher order nonlinear terms, reveal a comprehensive nonlinear dynamics phase diagram, which quantitatively explains the complex behaviors of GNEMRs.

  7. Measuring strain distributions in amorphous materials

    NASA Astrophysics Data System (ADS)

    Poulsen, Henning F.; Wert, John A.; Neuefeind, Jörg; Honkimäki, Veijo; Daymond, Mark

    2005-01-01

    A number of properties of amorphous materials including fatigue, fracture and component performance are governed by the magnitude of strain fields around inhomogeneities such as inclusions, voids and cracks. At present, localized strain information is only available from surface probes such as optical or electron microscopy. This is unfortunate because surface and bulk characteristics in general differ. Hence, to a large extent, the assessment of strain distributions relies on untested models. Here we present a universal diffraction method for characterizing bulk stress and strain fields in amorphous materials and demonstrate its efficacy by work on a material of current interest in materials engineering: a bulk metallic glass. The macroscopic response is shown to be less stiff than the atomic next-neighbour bonds because of structural rearrangements at the scale of 4-10 Å. The method is also applicable to composites comprising an amorphous matrix and crystalline inclusions.

  8. Survival of Bacillus megaterium strains in water.

    PubMed

    Palmada, F M; Sanchez-Rivas, C

    1996-01-01

    Cultures of Bacillus megaterium strains, producers or not of poly-beta-hydroxy-butyrate (PHB+ and PHB-) were submitted to several shift-downs: nutritional (one hundred fold dilution in saline water S or artificial fresh water ADA) or nutritional and osmotic (one hundred fold dilution in water or W). In all conditions tested, the wild type strain survived, duplicated five times and sporulated. However, the PHB- mutant strain showed a drastic loss of viability in water (< 0.1%) not observed when the shift was only nutritional (S or ADA). Discussion was focused on the advantages of the potential use of Bacillus megaterium as host for delivering bio-insecticides in waters instead of natural hosts such as B. thuringiensis strains. PMID:9017852

  9. Method of transferring strained semiconductor structure

    DOEpatents

    Nastasi, Michael A.; Shao, Lin

    2009-12-29

    The transfer of strained semiconductor layers from one substrate to another substrate involves depositing a multilayer structure on a substrate having surface contaminants. An interface that includes the contaminants is formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the deposited multilayer structure is bonded to a second substrate and is separated away at the interface, which results in transferring a multilayer structure from one substrate to the other substrate. The multilayer structure includes at least one strained semiconductor layer and at least one strain-induced seed layer. The strain-induced seed layer can be optionally etched away after the layer transfer.

  10. Strain Gauges Mounted To Retain Calibration

    NASA Technical Reports Server (NTRS)

    Butler, Barry L.

    1993-01-01

    Silicon-based semiconductor strain gauges mounted in such way they retain original calibration for several years instead of few months. Improvement effected by bonding gauges to ceramic substrates with glasses instead of epoxies as adhesives.

  11. Thin film strain gage development program

    NASA Technical Reports Server (NTRS)

    Grant, H. P.; Przybyszewski, J. S.; Anderson, W. L.; Claing, R. G.

    1983-01-01

    Sputtered thin-film dynamic strain gages of 2 millimeter (0.08 in) gage length and 10 micrometer (0.0004 in) thickness were fabricated on turbojet engine blades and tested in a simulated compressor environment. Four designs were developed, two for service to 600 K (600 F) and two for service to 900 K (1200 F). The program included a detailed study of guidelines for formulating strain-gage alloys to achieve superior dynamic and static gage performance. The tests included gage factor, fatigue, temperature cycling, spin to 100,000 G, and erosion. Since the installations are 30 times thinner than conventional wire strain gage installations, and any alteration of the aerodynamic, thermal, or structural performance of the blade is correspondingly reduced, dynamic strain measurement accuracy higher than that attained with conventional gages is expected. The low profile and good adherence of the thin film elements is expected to result in improved durability over conventional gage elements in engine tests.

  12. Strain field of a buried oxide aperture

    NASA Astrophysics Data System (ADS)

    Kießling, F.; Niermann, T.; Lehmann, M.; Schulze, J.-H.; Strittmatter, A.; Schliwa, A.; Pohl, U. W.

    2015-02-01

    The strain field of an AlOx current aperture, fabricated by selective oxidation of an AlAs/GaAs layer buried in a circular GaAs mesa, is studied. Components of the strain tensor for a thin cross-section lamella cut out of such a structure are evaluated from dark-field electron holography, proving the validity of simulations based on linear elasticity. Simulation of the entire structure is utilized to prepare mesa surfaces with tailored strain fields for controlling the nucleation site of InGaAs quantum dots. The experimental proof of strain simulations allows estimating the magnitude of piezoelectricity, yielding for the studied mesa structures a piezoelectric potential up to 50 mV.

  13. Can a strain yield a qubit?

    NASA Astrophysics Data System (ADS)

    Benjamin, Colin

    2015-03-01

    A Josepshon qubit is designed via the application of a tensile strain to a topological insulator surface, sandwiched between two s-wave superconductors. The strain applied leads to a shift in Dirac point without changing the conducting states existing on the surface of a topological insulator. This strain applied can be tuned to form a π-junction in such a structure. Combining two such junctions in a ring architecture leads to the ground state of the ring being in a doubly degenerate state- ``0'' and ``1'' states of the qubit. A qubit designed this way is easily controlled via the tunable strain. We report on the conditions necessary to design such a qubit. Finally the operating time of a single qubit phase gate is derived. This work was supported by funds from Dept. of Science and Technology (Nanomission), Govt. of India, Grant No. SR/NM/NS-1101/2011.

  14. Design parameters for borehole strain instrumentation

    NASA Astrophysics Data System (ADS)

    Gladwin, Michael T.; Hart, Rhodes

    1985-01-01

    The response of a borehole strain meter to hydrostatic and shear deformations in an isotropic medium is calculated to facilitate optimum instrument design and produce instrument response factors for parameters typically encountered in installed instruments. Results for an empty borehole are first compared with results for an instrument in intimate contact with the surrounding rock. The effects of the grout used to install the instrument are then examined. Where possible, analytic forms for the response factors are given. Results for typical installations are then presented in graphical form for optimizing instrument design in an environment of known elastic parameters. Alternatively, the results may be applied in the measurement of unknown strain signals, to correct for instrument response or to provide in-situ estimates of the elastic properties of the environment by examination of observed strain response to known strain signals.

  15. Broken Bones, Sprains, and Strains (For Parents)

    MedlinePlus

    ... 5 Things to Know About Zika & Pregnancy Broken Bones, Sprains, and Strains KidsHealth > For Parents > Broken Bones, ... home. What to Do: For a Suspected Broken Bone: Do not move a child whose injury involves ...

  16. Dynamic Force Measurement with Strain Gauges

    ERIC Educational Resources Information Center

    Lee, Bruce E.

    1974-01-01

    Discusses the use of four strain gauges, a Wheatstone bridge, and an oscilloscope to measure forces dynamically. Included is an example of determining the centripetal force of a pendulum in a general physics laboratory. (CC)

  17. Silicon ribbon stress-strain activities

    NASA Technical Reports Server (NTRS)

    Wada, B. K.; Shih, C. F.; Kuo, C. P.; Phillips, W. M.

    1984-01-01

    The finite element method is used to investigate stress/strain in silicon ribbon. Failure considerations such as residual stress, buckling material non-linearity and creep are discussed. Temperature profiles are presented.

  18. [Improvement of Trichoderma strains for biocontrol].

    PubMed

    Benítez, T; Rey, M; Delgado-Jarana, J; Rincón, A M; Limón, M C

    2000-03-01

    The use of the fungal genus Trichoderma to control fungal plant diseases is a promising alternative to the use of chemical compounds. The aim of this work has been to obtain Trichoderma strains with improved capacity as biological control agents. To do so, the hydrolytic capacity on fungal cell walls of strains of the fungus Trichoderma harzianum has been increased. On one hand, transformation experiments with genes which coded for chitinases and glucanases have been carried out in T. harzianumstra ins. On the other hand, the medium composition has also been modified in order to eliminate proteolytic degradation of some of the overproduced enzymes. Finally, hybrid chitinolytic enzymes with substrate-binding domains have been produced as an alternative to obtain improved biocontrol strains. The transformant strains, when compared with the wild type, showed improved antifungal capacity against the phytopathogenic fungus Rhizoctonia solani, in in vitro experiments. PMID:15762779

  19. Heat strain during explosive ordnance disposal.

    PubMed

    Stewart, Ian B; Rojek, Amanda M; Hunt, Andrew P

    2011-08-01

    Bomb technicians perform their work while encapsulated in explosive ordnance disposal suits. Designed primarily for safety, these suits have an unintended consequence of impairing the body's natural mechanisms for heat dissipation. Consequently, bomb technicians are known to experience symptoms of heat illness while performing their work. This research provides the first field based analysis of heat strain in bomb technicians. Six participants undertook simulated operational tasks across 2 days of variable climate. All subjects demonstrated high levels of heat strain as evidenced by elevated heart rate, core body temperature, and physiological strain index. Participants also reported signs and symptoms associated with heat illness. These results were exacerbated by more intense physical activity despite being undertaken in a cooler environment. The universal experience of heat strain in this sample has significant implications for the health of bomb technicians and additional research examining methods to improve temperature regulation and performance is warranted. PMID:21882791

  20. The Development of Electrical Strain Gages

    NASA Technical Reports Server (NTRS)

    De Forest, A V; Leaderman, H

    1940-01-01

    The design, construction, and properties of an electrical-resistance strain gage consisting of fine wires molded in a laminated plastic are described. The properties of such gages are discussed and also the problems of molding of wires in plastic materials, temperature compensation, and cementing and removal of the gages. Further work to be carried out on the strain gage, together with instrument problems, is discussed.

  1. Geometric reconstruction using tracked ultrasound strain imaging

    NASA Astrophysics Data System (ADS)

    Pheiffer, Thomas S.; Simpson, Amber L.; Ondrake, Janet E.; Miga, Michael I.

    2013-03-01

    The accurate identification of tumor margins during neurosurgery is a primary concern for the surgeon in order to maximize resection of malignant tissue while preserving normal function. The use of preoperative imaging for guidance is standard of care, but tumor margins are not always clear even when contrast agents are used, and so margins are often determined intraoperatively by visual and tactile feedback. Ultrasound strain imaging creates a quantitative representation of tissue stiffness which can be used in real-time. The information offered by strain imaging can be placed within a conventional image-guidance workflow by tracking the ultrasound probe and calibrating the image plane, which facilitates interpretation of the data by placing it within a common coordinate space with preoperative imaging. Tumor geometry in strain imaging is then directly comparable to the geometry in preoperative imaging. This paper presents a tracked ultrasound strain imaging system capable of co-registering with preoperative tomograms and also of reconstructing a 3D surface using the border of the strain lesion. In a preliminary study using four phantoms with subsurface tumors, tracked strain imaging was registered to preoperative image volumes and then tumor surfaces were reconstructed using contours extracted from strain image slices. The volumes of the phantom tumors reconstructed from tracked strain imaging were approximately between 1.5 to 2.4 cm3, which was similar to the CT volumes of 1.0 to 2.3 cm3. Future work will be done to robustly characterize the reconstruction accuracy of the system.

  2. High Temperature Strain Gage Calibration Fixture

    NASA Technical Reports Server (NTRS)

    Vranas, T. (Inventor)

    1976-01-01

    An apparatus and method are described for calibrating high temperature strain gases which serve for both dead weight and constant deflection measurements. A cantilever support arm allows the test unit to slide into a furnace while one end is subjected to bending strain either by hanging weights upon it or by deflecting it with a push rod. The dual nature of the fixture permits both tests to be run without change of the test specimen or removal from the furnace.

  3. High-Temperature Adhesive Strain Gage Developed

    NASA Technical Reports Server (NTRS)

    Pereira, J. Michael; Roberts, Gary D.

    1997-01-01

    Researchers at the NASA Lewis Research Center have developed a unique strain gage and adhesive system for measuring the mechanical properties of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial strain gages and adhesives. For example, typical commercial strain gage adhesives require a postcure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass-transition temperature of the polymer. In addition, although typical commercial strain gages can be used for short times at temperatures up to 370 C, their long-term use is limited to 230 C. This precludes their use for testing some high-temperature polyimides near their maximum temperature capability. Lewis' strain gage and adhesive system consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer after the specimen has been cured but prior to the normal postcure cycle. The gage is applied with an adhesive specially formulated to cure under the specimen postcure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each strain gage after it was applied to a specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. For these tests, which included static tension, thermal exposure, and creep tests, the gage and adhesive system performed within normal strain gage specifications at 315 C. An example of the performance characteristics of the gage can be seen in the figure, which compares the strain gage measurement on a polyimide specimen at 315 C with an extensometer measurement.

  4. [Consumption of hydrocarbons by psychrotolerant degrader strains].

    PubMed

    Andeeva, I S; Emel'ianova, E K; Ol'kin, S E; Reznikova, I K; Zagrebel'nyĭ, S N; Repin, V E

    2007-01-01

    Oil-oxidizing microorganisms have been sampled in various regions of Siberia and used in strain associations, which degrade n-alkanes of oil from various fields by 64-92% after 6 days of growth in a wide temperature range. These strains are salt-tolerant and psychrotolerant. They are compatible with aboriginal soil microflora. Promising results have been obtained in experiments on growing plants on oil-polluted soil purified with a biodegrader of this series. PMID:17476811

  5. Strain limit criteria to predict failure

    SciTech Connect

    Flanders, H.E.

    1995-12-31

    In recent years extensive effort has been expended to qualify existing structures for conditions that are beyond the original design basis. Determination of the component failure load is useful for this type of evaluation. This paper presents criteria based upon strain limits to predict the load at failure. The failure modes addressed are excessive plastic deformations, localized plastic strains, and structural instability. The effects of analytical method sophistication, as built configurations, material properties degradation, and stress state are addressed by the criteria.

  6. Hydraulic Calibrator for Strain-Gauge Balances

    NASA Technical Reports Server (NTRS)

    Skelly, Kenneth; Ballard, John

    1987-01-01

    Instrument for calibrating strain-gauge balances uses hydraulic actuators and load cells. Eliminates effects of nonparallelism, nonperpendicularity, and changes of cable directions upon vector sums of applied forces. Errors due to cable stretching, pulley friction, and weight inaccuracy also eliminated. New instrument rugged and transportable. Set up quickly. Developed to apply known loads to wind-tunnel models with encapsulated strain-gauge balances, also adapted for use in calibrating dynamometers, load sensors on machinery and laboratory instruments.

  7. Load cell having strain gauges of arbitrary location

    DOEpatents

    Spletzer, Barry

    2007-03-13

    A load cell utilizes a plurality of strain gauges mounted upon the load cell body such that there are six independent load-strain relations. Load is determined by applying the inverse of a load-strain sensitivity matrix to a measured strain vector. The sensitivity matrix is determined by performing a multivariate regression technique on a set of known loads correlated to the resulting strains. Temperature compensation is achieved by configuring the strain gauges as co-located orthogonal pairs.

  8. Strain-tunable Josephson current in graphene-superconductor junction

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Liu, Y.; Wang, B.

    2013-10-01

    Strain effects on Josephson current in a graphene-superconductor junction are explored theoretically. It is demonstrated that the supercurrent is an oscillatory function of zigzag direction strain with a strain-dependent oscillating frequency. Interestingly, it is found that the Josephson current under armchair direction strain can be turned on/off with a cutoff strain. In view of the on/off properties of the Josephson current, we propose the strained graphene Josephson junction to be utilized as a supercurrent switch.

  9. A high-strain-rate superplastic ceramic.

    PubMed

    Kim, B N; Hiraga, K; Morita, K; Sakka, Y

    2001-09-20

    High-strain-rate superplasticity describes the ability of a material to sustain large plastic deformation in tension at high strain rates of the order of 10-2 to 10-1 s-1 and is of great technological interest for the shape-forming of engineering materials. High-strain-rate superplasticity has been observed in aluminium-based and magnesium-based alloys. But for ceramic materials, superplastic deformation has been restricted to low strain rates of the order of 10-5 to 10-4 s-1 for most oxides and nitrides with the presence of intergranular cavities leading to premature failure. Here we show that a composite ceramic material consisting of tetragonal zirconium oxide, magnesium aluminate spinel and alpha-alumina phases exhibits superplasticity at strain rates up to 1 s-1. The composite also exhibits a large tensile elongation, exceeding 1,050 per cent for a strain rate of 0.4 s-1. The tensile flow behaviour and deformed microstructure of the material indicate that superplasticity is due to a combination of limited grain growth in the constitutive phases and the intervention of dislocation-induced plasticity in the zirconium oxide phase. We suggest that the present results hold promise for the application of shape-forming technologies to ceramic materials. PMID:11565026

  10. Fermentation studies using Saccharomyces diastaticus yeast strains

    SciTech Connect

    Erratt, J.A.; Stewart, G.G.

    1981-01-01

    The yeast species, Saccharomyces diastaticus, has the ability to ferment starch and dextrin, because of the extracellular enzyme, glucoamylase, which hydrolyzes the starch/dextrin to glucose. A number of nonallelic genes--DEX 1, DEX 2, and dextrinase B which is allelic to STA 3--have been isolated, which impart to the yeast the ability to ferment dextrin. Various diploid yeast strains were constructed, each being either heterozygous or homozygous for the individual dextrinase genes. Using 12 (sup 0) plato hopped wort (30% corn adjunct) under agitated conditions, the fermentation rates of the various diploid yeast strains were monitored. A gene-dosage effect was exhibited by yeast strains containing DEX 1 or DEX 2, however, not with yeast strains containing dextrinase B (STA 3). The fermentation and growth rates and extents were determined under static conditions at 14.4 C and 21 C. With all yeast strains containing the dextrinase genes, both fermentation and growth were increased at the higher incubation temperature. Using 30-liter fermentors, beer was produced with the various yeast strains containing the dextrinase genes and the physical and organoleptic characteristics of the products were determined. The concentration of glucose in the beer was found to increase during a 3-mo storage period at 21 C, indicating that the glucoamylase from Saccharomyces diastaticus is not inactivated by pasteurization. (Refs. 36).

  11. Strain Tuning of Ferroelectric Thin Films *

    NASA Astrophysics Data System (ADS)

    Schlom, Darrell G.; Chen, Long-Qing; Eom, Chang-Beom; Rabe, Karin M.; Streiffer, Stephen K.; Triscone, Jean-Marc

    2007-08-01

    Predictions and measurements of the effect of biaxial strain on the properties of epitaxial ferroelectric thin films and superlattices are reviewed. Results for single-layer ferroelectric films of biaxially strained SrTiO3, BaTiO3, and PbTiO3 as well as PbTiO3/SrTiO3 and BaTiO3/SrTiO3 superlattices are described. Theoretical approaches, including first principles, thermodynamic analysis, and phase-field models, are applied to these biaxially strained materials, the assumptions and limitations of each technique are explained, and the predictions are compared. Measurements of the effect of biaxial strain on the paraelectric-to-ferroelectric transition temperature (TC) are shown, demonstrating the ability of percent-level strains to shift TC by hundreds of degrees in agreement with the predictions that predated such experiments. Along the way, important experimental techniques for characterizing the properties of strained ferroelectric thin films and superlattices, as well as appropriate substrates on which to grow them, are mentioned.

  12. Fiber optic strain monitoring for pipelines

    SciTech Connect

    Berthold, J.W.

    1998-04-08

    The objective of this project was to demonstrate the feasibility of using fiber optic Bragg grating sensors (BGS) to measure axial and bending strain in pipes. Work was performed by McDermott Technology Inc. (MTI) and included BGS design and procurement. In addition to the pipe strain testing, a number of BGS evaluations were performed. Several methods were evaluated to protect and encapsulate the BGS, which are embedded inside an optical fiber, and strain transfer tests were performed on two of the encapsulation approaches. A high strain bending test to failure was performed on one BGS. A special test section was used to characterize the performance of the BGS and compare to standard electrical resistance foil strain gages. Two sets of pipe strain tests were performed. In the first test series, optical fiber was positioned along the pipe test section and embedded BGS were attached directly to the outside of the pipe wall. In the second tests series, the BGS were encapsulated inside a stainless steel tube which was attached to the outside of the pipe wall. All the tests were successfully completed, the data analyzed, and the results summarized in this report.

  13. [Screening of strain producing extracellular penicillin acylase].

    PubMed

    Wang, Z; Han, W; Men, D; Wang, Q

    1992-04-01

    Ninety-eight strains having extracellular penicillin acylase activity were derived from soil samples by colour-developing method. 10 strains of them possess higher activity of penicillin acylase. All of those are found to be Bacillus megaterium. The optimum condition of enzyme production was investigated with the strain No. 46 which is from No. 247 by single colony isolation. The productivity of penicillin acylase in the optimum condition have been enhanced 2.5 times more than that in the screening condition. The mutant strain, Bacillus megaterium UL-81, which penicillin acylase activity reached the level of 723u/100ml of broth was obtained from No. 46 by treatment with physical and chemical factors. The penicillin acylase activity of UL-81 can reach 820u/100 ml in 500L fermentor. The mutant strain differed from parent strain in the morphology of colony, the size of cells, the effect of concentration and the addition time of phenylacetic acid on the production of penicillin acylase. PMID:1598760

  14. A closer look at prion strains

    PubMed Central

    Solforosi, Laura; Milani, Michela; Mancini, Nicasio; Clementi, Massimo; Burioni, Roberto

    2013-01-01

    Prions are infectious proteins that are responsible for transmissible spongiform encephalopathies (TSEs) and consist primarily of scrapie prion protein (PrPSc), a pathogenic isoform of the host-encoded cellular prion protein (PrPC). The absence of nucleic acids as essential components of the infectious prions is the most striking feature associated to these diseases. Additionally, different prion strains have been isolated from animal diseases despite the lack of DNA or RNA molecules. Mounting evidence suggests that prion-strain-specific features segregate with different PrPSc conformational and aggregation states. Strains are of practical relevance in prion diseases as they can drastically differ in many aspects, such as incubation period, PrPSc biochemical profile (e.g., electrophoretic mobility and glycoform ratio) and distribution of brain lesions. Importantly, such different features are maintained after inoculation of a prion strain into genetically identical hosts and are relatively stable across serial passages. This review focuses on the characterization of prion strains and on the wide range of important implications that the study of prion strains involves. PMID:23357828

  15. Strain-displacement relations for strain engineering in single-layer 2d materials

    NASA Astrophysics Data System (ADS)

    Midtvedt, Daniel; Lewenkopf, Caio H.; Croy, Alexander

    2016-03-01

    We investigate the electromechanical coupling in single-layer 2d materials. For non-Bravais lattices, we find important corrections to the standard macroscopic strain-microscopic atomic-displacement theory. We put forward a general and systematic approach to calculate strain-displacement relations for several classes of 2d materials. We apply our findings to graphene as a study case, by combining a tight binding and a valence force-field model to calculate electronic and mechanical properties of graphene nanoribbons under strain. The results show good agreement with the predictions of the Dirac equation coupled to continuum mechanics. For this long wave-limit effective theory, we find that the strain-displacement relations lead to a renormalization correction to the strain-induced pseudo-magnetic fields. A similar renormalization is found for the strain-induced band-gap of black phosphorous. Implications for nanomechanical properties and electromechanical coupling in 2d materials are discussed.

  16. Internal elastic strains in an IF steel following changes in strain path

    SciTech Connect

    Wilson, D.V.; Bate, P.S.

    1996-08-01

    Residual elastic strains present in an IF steel following rolling and subsequent tensile deformation have been evaluated using X-ray diffraction. It was possible to decompose diffraction profiles into two symmetrical components notionally corresponding to dislocation walls and cell interiors and so estimate the volume fractions and mean elastic strains associated with these components of the microstructure following different deformation modes. The residual long range elastic strains were very small following rolling, but they were much greater following subsequent tensile elongation to macroscopic yield. The mean strains could only account for about one-third of the strain induced anisotropy of flow stress. It is concluded that insufficient dislocations accumulate at cell walls at macroscopic yield following a path change to give homogeneous loading of the dislocation walls, and that this effect can account for the difference between the macroscopic mechanical behavior and predictions from the X-ray strain measurements.

  17. Strain rate change tests with the Split Hopkinson Bar method

    NASA Astrophysics Data System (ADS)

    Isakov, M.; Kokkonen, J.; Östman, K.; Kuokkala, V.-T.

    2016-05-01

    In this paper, methods to produce rapid strain rate changes for strain rate sensitivity measurements in Split Hopkinson Bar arrangements are presented and discussed. Two different cases are considered: a strain rate change test within the high strain rate region in compression, and a tension test incorporating a large strain rate jump directly from the low strain rate region to high strain rates. The former method is based on the loading wave amplitude manipulation, while the latter method is based on the incorporation of a low strain rate loading device into a Tensile Split Hopkinson Bar apparatus.

  18. COMPARISON OF A REFERENCE STRAIN AND FOUR GEOGRAPHICAL STRAINS OF 'ARTEMIA' AS FOOD FOR WINTER FLOUNDER (PSEUDOPLEURONECTES AMERICANUS) LARVAE

    EPA Science Inventory

    A reference strain and four commercially available geographical strains of Artemia nauplii were each tested as a diet for winter flounder (Pseudopleuronectes americanus) larvae. The Reference strain was provided by the Artemia Reference Center, Ghent, Belgium. The geographical st...

  19. Complete Genome Sequence of Rat Cytomegalovirus Strain ALL-03 (Malaysian Strain).

    PubMed

    Balakrishnan, Krishnan Nair; Abdullah, Ashwaq Ahmed; Camalxaman, Siti Nazrina; Quah, Yi Wan; Abba, Yusuf; Hani, Homayoun; Loh, Hwei San; Kamal, Farina Mustaffa; Zeenathul, Nazariah Allaudin; Aini, Ideris; Omar, A R; Noordin, Mohamed Mustapha; Mohd Azmi, Mohd Lila

    2015-01-01

    The complete genome sequence of the ALL-03 strain of rat cytomegalovirus (RCMV) has been determined. The RCMV genome has a length of 197,958 bp and is arranged as a single unique sequence flanked by 504-bp terminal direct repeats. This strain is closely related to the English strain of RCMV in terms of genetic arrangement but differs slightly in size. PMID:26044413

  20. The influence of strain rate and hydrogen on the plane-strain ductility of Zircaloy cladding

    SciTech Connect

    Link, T.M.; Motta, A.T.; Koss, D.A.

    1998-03-01

    The authors studied the ductility of unirradiated Zircaloy-4 cladding under loading conditions prototypical of those found in reactivity-initiated accidents (RIA), i.e.: near plane-strain deformation in the hoop direction (transverse to the cladding axis) at room temperature and 300 C and high strain rates. To conduct these studies, they developed a specimen configuration in which near plane-strain deformation is achieved in the gage section, and a testing methodology that allows one to determine both the limit strain at the onset of localized necking and the fracture strain. The experiments indicate that there is little effect of strain rate (10{sup {minus}3} to 10{sup 2} s{sup {minus}1}) on the ductility of unhydrided Zircaloy tubing deformed under near plane-strain conditions at either room temperature or 300 C. Preliminary experiments on cladding containing 190 ppm hydrogen show only a small loss of fracture strain but no clear effect on limit strain. The experiments also indicate that there is a significant loss of Zircaloy ductility when surface flaws are present in the form of thickness imperfections.

  1. Bone strain magnitude is correlated with bone strain rate in tetrapods: implications for models of mechanotransduction

    PubMed Central

    Aiello, B. R.; Iriarte-Diaz, J.; Blob, R. W.; Butcher, M. T.; Carrano, M. T.; Espinoza, N. R.; Main, R. P.; Ross, C. F.

    2015-01-01

    Hypotheses suggest that structural integrity of vertebrate bones is maintained by controlling bone strain magnitude via adaptive modelling in response to mechanical stimuli. Increased tissue-level strain magnitude and rate have both been identified as potent stimuli leading to increased bone formation. Mechanotransduction models hypothesize that osteocytes sense bone deformation by detecting fluid flow-induced drag in the bone's lacunar–canalicular porosity. This model suggests that the osteocyte's intracellular response depends on fluid-flow rate, a product of bone strain rate and gradient, but does not provide a mechanism for detection of strain magnitude. Such a mechanism is necessary for bone modelling to adapt to loads, because strain magnitude is an important determinant of skeletal fracture. Using strain gauge data from the limb bones of amphibians, reptiles, birds and mammals, we identified strong correlations between strain rate and magnitude across clades employing diverse locomotor styles and degrees of rhythmicity. The breadth of our sample suggests that this pattern is likely to be a common feature of tetrapod bone loading. Moreover, finding that bone strain magnitude is encoded in strain rate at the tissue level is consistent with the hypothesis that it might be encoded in fluid-flow rate at the cellular level, facilitating bone adaptation via mechanotransduction. PMID:26063842

  2. Strain analysis and strain path modelling in the Loch Tollie gneisses, Gairloch, NW Scotland

    NASA Astrophysics Data System (ADS)

    Odling, N. E.

    A quantitative structural analysis is presented for the Loch Tullie gneisses of the Lewisian complex outcropping at Gairloch. The gneisses and the dykes they contain are folded into a large antiformal structure known as the Tollic Antiform. Quartz aggregates in quartzo-feldspathic gneisses have been used as finite strain markers in eleven specimens across the antiform. Two models, using rotational strain (simple shear) and irrotational strain (pure shear), are used to reconstruct the strain path. Results show that only the rotational strain model satisfies the strain data and the field evidence, and indicates a steeply northeast (75°) dipping shear plane and moderately northwest (55°) plunging shear direction, with a southwest-side-down sense of shear. A strain profile is constructed for the Tollie gneisses using the model and the attitude of gneissose layering. This shows increasing shear strain to the southwest to a maximum gamma value of approximately 8. The strain profile indicates a horizontal dextral displacement of 4.7 km and a vertical displacement of 6.8 km for the Tollie gneisses. The Tollie Antiform thus lies on the northeast margin of a large-scale shear zone, the main zone of deformation of which can be traced southwestwards some 4 km. Such a shear zone presents a major tectonic boundary within the Lewisian of northwest Scotland.

  3. Genome-Wide Transcription Study of Cryptococcus neoformans H99 Clinical Strain versus Environmental Strains

    PubMed Central

    Movahed, Elaheh; Munusamy, Komathy; Tan, Grace Min Yi; Looi, Chung Yeng; Tay, Sun Tee; Wong, Won Fen

    2015-01-01

    The infection of Cryptococcus neoformans is acquired through the inhalation of desiccated yeast cells and basidiospores originated from the environment, particularly from bird’s droppings and decaying wood. Three environmental strains of C. neoformans originated from bird droppings (H4, S48B and S68B) and C. neoformans reference clinical strain (H99) were used for intranasal infection in C57BL/6 mice. We showed that the H99 strain demonstrated higher virulence compared to H4, S48B and S68B strains. To examine if gene expression contributed to the different degree of virulence among these strains, a genome-wide microarray study was performed to inspect the transcriptomic profiles of all four strains. Our results revealed that out of 7,419 genes (22,257 probes) examined, 65 genes were significantly up-or down-regulated in H99 versus H4, S48B and S68B strains. The up-regulated genes in H99 strain include Hydroxymethylglutaryl-CoA synthase (MVA1), Mitochondrial matrix factor 1 (MMF1), Bud-site-selection protein 8 (BUD8), High affinity glucose transporter 3 (SNF3) and Rho GTPase-activating protein 2 (RGA2). Pathway annotation using DAVID bioinformatics resource showed that metal ion binding and sugar transmembrane transporter activity pathways were highly expressed in the H99 strain. We suggest that the genes and pathways identified may possibly play crucial roles in the fungal pathogenesis. PMID:26360021

  4. Imploding Liner Material Strength Measurements at High-Strain and High Strain Rate

    SciTech Connect

    Bartsch, R.R.; Lee, H.; Holtkamp, D.; Wright, B.; Stokes, J.; Morgan, D.; Anderson, W.; Broste, W.

    1998-10-18

    Imploding, cylindrical liners provide a unique, shockless means of simultaneously accessing high strain and high-strain-rate for measurement of strength of materials in plastic flow. The radial convergence in the liner geometry results in the liner thickening as the circumference becomes smaller. Strains of up to {approximately}1.25 and strain rates of up to {approximately}10{sup 6} sec{sup -1} can be readily achieved in a material sample placed inside of an aluminum driver liner, using the Pegasus II capacitor bank. This provides yield strength data at conditions where none presently exists. The heating from work done against the yield strength is measured with multichannel pyrometry from infrared radiation emitted by the material sample. The temperature data as a function of liner position are unfolded to give the yield strength along the strain, strain-rate trajectory. Proper design of the liner and sample configuration ensures that the current diffused into the sample adds negligible heating. An important issue, in this type of temperature measurement, is shielding of the pickup optics from other sources of radiation. At strains greater than those achievable on Pegasus, e.g. the LANL Atlas facility, some materials may be heated all the way to melt by this process. Recent data on 6061-T6 Aluminum will be compared with an existing model for strain and strain-rate heating. The liner configuration and pyrometry diagnostic will also be discussed.

  5. A numerical method for determining the strain rate intensity factor under plane strain conditions

    NASA Astrophysics Data System (ADS)

    Alexandrov, S.; Kuo, C.-Y.; Jeng, Y.-R.

    2016-07-01

    Using the classical model of rigid perfectly plastic solids, the strain rate intensity factor has been previously introduced as the coefficient of the leading singular term in a series expansion of the equivalent strain rate in the vicinity of maximum friction surfaces. Since then, many strain rate intensity factors have been determined by means of analytical and semi-analytical solutions. However, no attempt has been made to develop a numerical method for calculating the strain rate intensity factor. This paper presents such a method for planar flow. The method is based on the theory of characteristics. First, the strain rate intensity factor is derived in characteristic coordinates. Then, a standard numerical slip-line technique is supplemented with a procedure to calculate the strain rate intensity factor. The distribution of the strain rate intensity factor along the friction surface in compression of a layer between two parallel plates is determined. A high accuracy of this numerical solution for the strain rate intensity factor is confirmed by comparison with an analytic solution. It is shown that the distribution of the strain rate intensity factor is in general discontinuous.

  6. Heterogeneity within Corynebacterium minutissimum strains is explained by misidentified Corynebacterium amycolatum strains.

    PubMed

    Zinkernagel, A S; von Graevenitz, A; Funke, G

    1996-09-01

    Forty-eight clinical strains that were tentatively identified as Corynebacterium minutissimum on the basis of standard biochemical reactions (Hollis-Weaver tables) as well as by the use of the API (RAPID) Coryne system were examined further. Two different groups of strains were observed. The first group (including the type strain of C minutissimum) contained 27 strains showing creamy colonies. These strains grew homogeneously in 6.5% NaCl broth, exhibited DNase activity, were susceptible to the vibriocidal compound O/129, produced succinic acid, and contained mycolic acids. The second group comprised 21 strains with dry colonies. They grew in clumps at the surface of 6.5% NaCl broth, DNase activity was not detected, they were resistant against O/129, produced large amounts of propionic acid, and mycolic acids were not detected. In combination with quantitative DNA-DNA hybridizations, it was demonstrated that strains of the second cluster belonged, in fact, to C amycolatum. Furthermore, it was observed that a few C minutissimum strains may also ferment mannitol. These data indicate that the clinical microbiologist must be careful not to misidentify C amycolatum strains as C minutissimum. PMID:8816598

  7. True stress-strain curve acquisition for irradiated stainless steel including the range exceeding necking strain

    NASA Astrophysics Data System (ADS)

    Kamaya, Masayuki; Kitsunai, Yuji; Koshiishi, Masato

    2015-10-01

    True stress-strain curves were obtained for irradiated 316L stainless steel by a tensile test and by a curve estimation procedure. In the tensile test, the digital image correlation technique together with iterative finite element analysis was applied in order to identify curves for strain larger than the necking strain. The true stress-strain curves were successfully obtained for the strain of more than 0.4 whereas the necking strain was about 0.2 in the minimum case. The obtained true stress-strain curves were approximated well with the Swift-type equation including the post-necking strain even if the exponential constant n was fixed to 0.5. Then, the true stress-strain curves were estimated by a curve estimation procedure, which was referred to as the K-fit method. Material properties required for the K-fit method were the yield and ultimate strengths or only the yield strength. Some modifications were made for the K-fit method in order to improve estimation accuracy for irradiated stainless steels.

  8. Stress-Strain Relation and strain-Induced Crystallization in Rubber

    SciTech Connect

    Toki,S.

    2006-01-01

    Rubber is composed of flexible chains and network points. Theory of rubber elasticity succeeds to elucidate stress-strain relation of rubber using the inverse Langevin equation of entropy modulus. However, actual rubber is much different from ideal networks composed of ideal rubber chains. Network points may not distribute homogeneously and the molecular weight between two network points may show wide distribution. Flexible chains show strain-induced crystallization. Recent synchrotron X-ray and simultaneous stress-strain measurements reveal that strain-induced crystallization reduces the stress by increasing the length of molecules along the stretching direction. Also, strain-induced crystals are created not at the middle of the network points, but at the close location to the network points. The hybrid structure of strain-induced crystallites and network points may be stronger than network points alone. Therefore, strain induced crystallization may increase the tensile strength of rubber by two mechanisms, they are, increase of elongation at break and reinforcement of network points. Natural rubber has biotic network points in nature. After vulcanization, the biotic network may contribute the superior toughness of NR, comparing to IR. Carbon filled NR also shows strain induced crystallization. In order to acquire high tensile strength, molecules should have higher flexibility to perform strain induced crystallization by selecting a kind of carbon blacks, an accelerator and a curing condition.

  9. Elastocaloric cooling processes: The influence of material strain and strain rate on efficiency and temperature span

    NASA Astrophysics Data System (ADS)

    Schmidt, Marvin; Schütze, Andreas; Seelecke, Stefan

    2016-06-01

    This paper discusses the influence of material strain and strain rate on efficiency and temperature span of elastocaloric cooling processes. The elastocaloric material, a newly developed quaternary Ni-Ti-Cu-V alloy, is characterized at different maximum strains and strain rates. The experiments are performed with a specially designed test setup, which enables the measurement of mechanical and thermal process parameters. The material efficiency is compared to the efficiency of the Carnot process at equivalent thermal operation conditions. This method allows for a direct comparison of the investigated material with other caloric materials.

  10. Inexpensive Implementation of Many Strain Gauges

    NASA Technical Reports Server (NTRS)

    Berkun, Andrew C.

    2010-01-01

    It has been proposed to develop arrays of strain gauges as arrays of ordinary metal film resistors and associated electronic readout circuitry on printed circuit boards or other suitable substrates. This proposal is a by-product of a development of instrumentation utilizing metal film resistors on printed-circuit boards to measure temperatures at multiple locations. In the course of that development, it was observed that in addition to being sensitive to temperature, the metal film resistors were also sensitive to strains in the printed-circuit boards to which they were attached. Because of the low cost of ordinary metal film resistors (typically <$0.01 apiece at 2007 prices), the proposal could enable inexpensive implementation of arrays of many (e.g., 100 or more) strain gauges, possibly concentrated in small areas. For example, such an array could be designed for use as a computer keyboard with no moving parts, as a device for sensing the shape of an object resting on a surface, or as a device for measuring strains at many points on a mirror, a fuel tank, an airplane wing, or other large object. Ordinarily, the effect of strain on resistance would be regarded as a nuisance in a temperature-measuring application, and the effect of temperature on resistance would be regarded as a nuisance in a strain-measuring application. The strain-induced changes in resistance of the metal film resistors in question are less than those of films in traditional strain gauges. The main novel aspect of present proposal lies in the use of circuitry affording sufficient sensitivity to measure strain plus means for compensating for the effect of temperature. For an array of metal film resistors used as proposed, the readout circuits would include a high-accuracy analog-to-digital converter fed by a low noise current source, amplifier chain, and an analog multiplexer chain. Corrections would be provided by use of high-accuracy calibration resistors and a temperature sensor. By use of

  11. Volume strain within the Geysers geothermal field

    SciTech Connect

    Mossop, Antony; Segall, Paul

    1999-12-10

    During the 1970s and 1980s. The Geysers geothermal region was rapidly developed as a site of geothermal power production. The likelihood that this could cause significant strain within the reservoir, with corresponding surface displacements, led to a series of deformation monitoring surveys. In 1973, 1975, 1977, and 1980, The Geysers region was surveyed using first-order, class I, spirit leveling. In 1994, 1995, and 1996, many of the leveling control monuments were resurveyed using high-precision Global Positioning System receivers. The two survey methods are reconciled using the GEOID96 geoid model. The displacements are inverted to determine volume strain within the reservoir. For the period 1980-1994, peak volume strains in excess of 5x10{sup -4} are imaged. There is an excellent correlation between the observed changes in reservoir steam pressures and the imaged volume strain. If reservoir pressure changes are inducing volume strain, then the reservoir quasi-static bulk modulus K must be <4.6x10{sup 9} Pa. However, seismic velocities indicate a much stiffer reservoir with K=3.4x10{sup 10} Pa. This apparent discrepancy is shown to be consistent with predicted frequency dependence in K for fractured and water-saturated rock. Inversion of surface deformation data therefore appears to be a powerful method for imaging pressure change within the body of the reservoir. Correlation between induced seismicity at The Geysers and volume strain is observed. However, earthquake distribution does not appear to have a simple relationship with volume strain rate. (c) 1999 American Geophysical Union.

  12. Psychological strains found in the suicides of 72 celebrities.

    PubMed

    Zhang, Jie; Tan, Jiandan; Lester, David

    2013-07-01

    The interpretation of suicide involves theories from many disciplines, and the strain theory of suicide is a social-psychological model that attempts to account for this complicated behavior. We have earlier explored the presence of psychological strains in a number of diverse samples of suicides and in the present study, we identified the strains experienced throughout the lives as documented in the biographies of 72 celebrities. The biographies were systematically identified through a number of requirements and composed by one of the authors of this study years before the strain theory of suicide was proposed. A graduate student coder, who was unaware of the strain theory of suicide, was hired to carry out a content analysis of the biography essays and categorize the life events and the responses of the suicide in terms of the four types of strains. Of the 72 suicides, one had no strains, one had all the four strains, four had only one, 30 had two, and 36 had three strains. The most common strain was aspiration strain (97%), followed by deprivation strain (89%), value strain (54%) and coping deficiency strain (4%). It is also noted that religious celebrities were more likely to experience value strain, while those celebrities who had experienced a downhill path in their careers were more likely to experience deprivation and coping strains. This analysis of the 72 celebrity suicides supported the strain theory of suicide. PMID:23462347

  13. The Effect of Ivermectin in Seven Strains of Aedes aegypti (Diptera: Culicidae) Including a Genetically Diverse Laboratory Strain and Three Permethrin Resistant Strains

    PubMed Central

    Deus, K. M.; Saavedra-rodriguez, K.; Butters, M. P.; Black, W. C.; Foy, B. D.

    2014-01-01

    Seven different strains of Aedes aegypti (L.), including a genetically diverse laboratory strain, three laboratory-selected permethrin-resistant strains, a standard reference strain, and two recently colonized strains were fed on human blood containing various concentrations of ivermectin. Ivermectin reduced adult survival, fecundity, and hatch rate of eggs laid by ivermectin-treated adults in all seven strains. The LC50 of ivermectin for adults and the concentration that prevented 50% of eggs from hatching was calculated for all strains. Considerable variation in adult survival after an ivermectin-bloodmeal occurred among strains, and all three permethrin-resistant strains were significantly less susceptible to ivermectin than the standard reference strain. The hatch rate after an ivermectin bloodmeal was less variable among strains, and only one of the permethrin-resistant strains differed significantly from the standard reference strain. Our studies suggest that ivermectin induces adult mortality and decreases the hatch rate of eggs through different mechanisms. A correlation analysis of log-transformed LC50 among strains suggests that permethrin and ivermectin cross-resistance may occur. PMID:22493855

  14. Anisotropic nature of radially strained metal tubes

    NASA Astrophysics Data System (ADS)

    Strickland, Julie N.

    Metal pipes are sometimes swaged by a metal cone to enlarge them, which increases the strain in the material. The amount of strain is important because it affects the burst and collapse strength. Burst strength is the amount of internal pressure that a pipe can withstand before failure, while collapse strength is the amount of external pressure that a pipe can withstand before failure. If the burst or collapse strengths are exceeded, the pipe may fracture, causing critical failure. Such an event could cost the owners and their customers millions of dollars in clean up, repair, and lost time, in addition to the potential environmental damage. Therefore, a reliable way of estimating the burst and collapse strength of strained pipe is desired and valuable. The sponsor currently rates strained pipes using the properties of raw steel, because those properties are easily measured (for example, yield strength). In the past, the engineers assumed that the metal would be work-hardened when swaged, so that yield strength would increase. However, swaging introduces anisotropic strain, which may decrease the yield strength. This study measured the yield strength of strained material in the transverse and axial direction and compared them to raw material, to determine the amount of anisotropy. This information will be used to more accurately determine burst and collapse ratings for strained pipes. More accurate ratings mean safer products, which will minimize risk for the sponsor's customers. Since the strained metal has a higher yield strength than the raw material, using the raw yield strength to calculate burst and collapse ratings is a conservative method. The metal has even higher yield strength after strain aging, which indicates that the stresses are relieved. Even with the 12% anisotropy in the strained and 9% anisotropy in the strain aged specimens, the raw yield strengths are lower and therefore more conservative. I recommend that the sponsor continue using the raw

  15. [Acetobutylic fermentation: strains and regional raw materials].

    PubMed

    Benassi, F O; Bloos, R K; de Rambaldo, L A

    1983-01-01

    The purpose of the present work was to show, as a first stage, that it is possible to characterize autochtohnous strains of Clostridium acetobutilicum of a good solvent producing capacity, specially N-butanol, through the utilization of suitable techniques for isolating anaerobic microorganisms. Cassava roots were employed as raw material using suitable culture media and an anaerobic jar of cold catalyst. The fermentative capacity of the strains thus isolated was evaluated against a control strain of Clostridium acetobutilicum. Even though some of the strains showed a greater solvent producing power, most of them showed lower fermentation capacity than the control strain, which could be increased, by applying successive thermic treatments. As a second stage, and due to the low cost production of cassava in the Province of Misiones, we studied its utilization as an acetone-butanol fermentation substrate. Mashes composed of binary mixtures of cassava flour and variable amounts of integral flour maize or soy were treated with selected "starters" of Clostridium acetobutilicum, being further processed according to standardized techniques in order to obtain the already mentioned solvents. Mashes concentration influence was also studied using culture media the composition of which proved to be excellent in all experiments carried out under "static system" conditions. The highest fermentative yields (maximum value recorded: 26,20 g of total solvents, with respect to dry solids), were recorded for mashes obtained from mixtures containing integral maize flour; these showed a higher degree of nutrients utilization than those prepared with integral soy flour. PMID:6400763

  16. Secretome analysis of Clostridium difficile strains.

    PubMed

    Boetzkes, Alexander; Felkel, Katharina Wiebke; Zeiser, Johannes; Jochim, Nelli; Just, Ingo; Pich, Andreas

    2012-08-01

    Clostridium difficile causes infections ranging from mild C. difficile-associated diarrhea to severe pseudomembranous colitis. Since 2003 new hypervirulent C. difficile strains (PCR ribotype 027) emerged characterized by a dramatically increased mortality. The secretomes of the three C. difficile strains CDR20291, CD196, and CD630 were analyzed and compared. Proteins were separated and analyzed by means of SDS--PAGE and LC-MS. MS data were analyzed using Mascot and proteins were checked for export signals with SecretomeP and SignalP. LC-MS analysis revealed 158 different proteins in the supernatant of C. difficile. Most of the identified proteins originate from the cytoplasm. Thirty-two proteins in CDR20291, 36 in CD196 and 26 in CD630 were identified to be secreted by C. difficile strains. Those were mainly S-layer proteins, substrate-binding proteins of ABC-transporters, cell wall hydrolases, pilin and unknown hypothetical proteins. Toxin A and toxin B were identified after growth in brain heart infusion medium using immunological techniques. The ADP-ribosyltransferase-binding component protein, which is a part of the binary toxin CDT, was only identified in the hypervirulent ribotype 027 strains. Further proteins that are secreted specifically by hypervirulent strains were identified. PMID:22398929

  17. Crack initiation under generalized plane strain conditions

    SciTech Connect

    Shum, D.K.M.; Merkle, J.G.

    1991-01-01

    A method for estimating the decrease in crack-initiation toughness, from a reference plane strain value, due to positive straining along the crack front of a circumferential flaw in a reactor pressure vessel is presented in this study. This method relates crack initiation under generalized plane strain conditions with material failure at points within a distance of a few crack-tip-opening displacements ahead of a crack front, and involves the formulation of a micromechanical crack-initiation model. While this study is intended to address concerns regarding the effects of positive out-of- plane straining on ductile crack initiation, the approach adopted in this work can be extended in a straightforward fashion to examine conditions of macroscopic cleavage crack initiation. Provided single- parameter dominance of near-tip fields exists in the flawed structure, results from this study could be used to examine the appropriateness of applying plane strain fracture toughness to the evaluation of circumferential flaws, in particular to those in ring-forged vessels which have no longitudinal welds. In addition, results from this study could also be applied toward the analysis of the effects of thermal streaming on the fracture resistance of circumferentially oriented flaws in a pressure vessel. 37 refs., 8 figs., 1 tab.

  18. Extraordinary strain hardening by gradient structure

    PubMed Central

    Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T.

    2014-01-01

    Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures. PMID:24799688

  19. Closure of fatigue cracks at high strains

    NASA Technical Reports Server (NTRS)

    Iyyer, N. S.; Dowling, N. E.

    1985-01-01

    Experiments were conducted on smooth specimens to study the closure behavior of short cracks at high cyclic strains under completely reversed cycling. Testing procedures and methodology, and closure measurement techniques, are described in detail. The strain levels chosen for the study cover from predominantly elastic to grossly plastic strains. Crack closure measurements are made at different crack lengths. The study reveals that, at high strains, cracks close only as the lowest stress level in the cycle is approached. The crack opening is observed to occur in the compressive part of the loading cycle. The applied stress needed to open a short crack under high strain is found to be less than for cracks under small scale yielding. For increased plastic deformations, the value of sigma sub op/sigma sub max is observed to decrease and approaches the value of R. Comparison of the experimental results with existing analysis is made and indicates the limitations of the small scale yielding approach where gross plastic deformation behavior occurs.

  20. Strains and tilts on crustal blocks

    NASA Technical Reports Server (NTRS)

    Bilham, R. G.; Beavan, R. J.

    1979-01-01

    Geodetic work done over the past century is examined to investigate block motion in areas of intense tectonic deformation, with special attention to geodetic releveling data obtained for Japan. Problems in interpreting strainmeter and tiltmeter to study the behavior of crustal blocks and block boundaries are discussed. Block dimensions of 5 to 50 km seem to occur frequently in regions of intense tectonic activity. Block boundaries are often considerably weaker than contiguous crustal blocks, resulting in a concentration of strains at boundaries and decrease of strains within blocks. Block to block variations in tilt phase and magnitude are observed. There is some evidence that block boundaries may exhibit strain-dependent elastic properties or respond viscoelastically, possibly accounting for the slow transmission of tectonic deformation reported in Japan. If nonlinear behavior is characteristic of regions fragmented by crustal blocks, it will generally not be possible to apply a site correction factor based on the observed distortion of tidal or seismic strains in interpreting secular strains.