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Sample records for acetic acid lactic

  1. Hydrogen production by fermentation using acetic acid and lactic acid.

    PubMed

    Matsumoto, Mitsufumi; Nishimura, Yasuhiko

    2007-03-01

    Microbial hydrogen production from sho-chu post-distillation slurry solution (slurry solution) containing large amounts of organic acids was investigated. The highest hydrogen producer, Clostridium diolis JPCC H-3, was isolated from natural environment and produced hydrogen at 6.03+/-0.15 ml from 5 ml slurry solution in 30 h. Interestingly, the concentration of acetic acid and lactic acid in the slurry solution decreased during hydrogen production. The substrates for hydrogen production by C. diolis JPCC H-3, in particular organic acids, were investigated in an artificial medium. No hydrogen was produced from acetic acid, propionic acid, succinic acid, or citric acid on their own. Hydrogen and butyric acid were produced from a mixture of acetic acid and lactic acid, showing that C. diolis. JPCC H-3 could produce hydrogen from acetic acid and lactic acid. Furthermore, calculation of the Gibbs free energy strongly suggests that this reaction would proceed. In this paper, we describe for the first time microbial hydrogen production from acetic acid and lactic acid by fermentation.

  2. Interaction effects of lactic acid and acetic acid at different temperatures on ethanol production by Saccharomyces cerevisiae in corn mash.

    PubMed

    Graves, Tara; Narendranath, Neelakantam V; Dawson, Karl; Power, Ronan

    2007-01-01

    The combined effects of lactic acid and acetic acid on ethanol production by S. cerevisiae in corn mash, as influenced by temperature, were examined. Duplicate full factorial experiments (three lactic acid concentrations x three acetic acid concentrations) were performed to evaluate the interaction between lactic and acetic acids on the ethanol production of yeast at each of the three temperatures, 30, 34, and 37 degrees C. Corn mash at 30% dry solids adjusted to pH 4 after lactic and acetic acid addition was used as the substrate. Ethanol production rates and final ethanol concentrations decreased (P<0.001) progressively as the concentration of combined lactic and acetic acids in the corn mash increased and the temperature was raised from 30 to 37 degrees C. At 30 degrees C, essentially no ethanol was produced after 96 h when 0.5% w/v acetic acid was present in the mash (with 0.5, 2, and 4% w/v lactic acid). At 34 and 37 degrees C, the final concentrations of ethanol produced by the yeast were noticeably reduced by the presence of 0.3% w/v acetic acid and >or=2% w/v lactic acid. It can be concluded that, as in previous studies with defined media, lactic acid and acetic acid act synergistically to reduce ethanol production by yeast in corn mash. In addition, the inhibitory effects of combined lactic and acetic acid in corn mash were more apparent at elevated temperatures.

  3. L-Lactic acid production from glycerol coupled with acetic acid metabolism by Enterococcus faecalis without carbon loss.

    PubMed

    Murakami, Nao; Oba, Mana; Iwamoto, Mariko; Tashiro, Yukihiro; Noguchi, Takuya; Bonkohara, Kaori; Abdel-Rahman, Mohamed Ali; Zendo, Takeshi; Shimoda, Mitsuya; Sakai, Kenji; Sonomoto, Kenji

    2016-01-01

    Glycerol is a by-product in the biodiesel production process and considered as one of the prospective carbon sources for microbial fermentation including lactic acid fermentation, which has received considerable interest due to its potential application. Enterococcus faecalis isolated in our laboratory produced optically pure L-lactic acid from glycerol in the presence of acetic acid. Gas chromatography-mass spectrometry analysis using [1, 2-(13)C2] acetic acid proved that the E. faecalis strain QU 11 was capable of converting acetic acid to ethanol during lactic acid fermentation of glycerol. This indicated that strain QU 11 restored the redox balance by oxidizing excess NADH though acetic acid metabolism, during ethanol production, which resulted in lactic acid production from glycerol. The effects of pH control and substrate concentration on lactic acid fermentation were also investigated. Glycerol and acetic acid concentrations of 30 g/L and 10 g/L, respectively, were expected to be appropriate for lactic acid fermentation of glycerol by strain QU 11 at a pH of 6.5. Furthermore, fed-batch fermentation with 30 g/L glycerol and 10 g/L acetic acid wholly exhibited the best performance including lactic acid production (55.3 g/L), lactic acid yield (0.991 mol-lactic acid/mol-glycerol), total yield [1.08 mol-(lactic acid and ethanol)]/mol-(glycerol and acetic acid)], and total carbon yield [1.06 C-mol-(lactic acid and ethanol)/C-mol-(glycerol and acetic acid)] of lactic acid and ethanol. In summary, the strain QU 11 successfully produced lactic acid from glycerol with acetic acid metabolism, and an efficient fermentation system was established without carbon loss.

  4. Acetate accumulation enhances mixed culture fermentation of biomass to lactic acid.

    PubMed

    Khor, Way Cern; Roume, Hugo; Coma, Marta; Vervaeren, Han; Rabaey, Korneel

    2016-10-01

    Lactic acid is a high-in-demand chemical, which can be produced through fermentation of lignocellulosic feedstock. However, fermentation of complex substrate produces a mixture of products at efficiencies too low to justify a production process. We hypothesized that the background acetic acid concentration plays a critical role in lactic acid yield; therefore, its retention via selective extraction of lactic acid or its addition would improve overall lactic acid production and eliminate net production of acetic acid. To test this hypothesis, we added 10 g/L of acetate to fermentation broth to investigate its effect on products composition and concentration and bacterial community evolution using several substrate-inoculum combinations. With rumen fluid inoculum, lactate concentrations increased by 80 ± 12 % (cornstarch, p < 0.05) and 16.7 ± 0.4 % (extruded grass, p < 0.05) while with pure culture inoculum (Lactobacillus delbrueckii and genetically modified (GM) Escherichia coli), a 4 to 23 % increase was observed. Using rumen fluid inoculum, the bacterial community was enriched within 8 days to >69 % lactic acid bacteria (LAB), predominantly Lactobacillaceae. Higher acetate concentration promoted a more diverse LAB population, especially on non-inoculated bottles. In subsequent tests, acetate was added in a semi-continuous percolation system with grass as substrate. These tests confirmed our findings producing lactate at concentrations 26 ± 5 % (p < 0.05) higher than the control reactor over 20 days operation. Overall, our work shows that recirculating acetate has the potential to boost lactic acid production from waste biomass to levels more attractive for application.

  5. Evaluation of clastogenicity of formic acid, acetic acid and lactic acid on cultured mammalian cells.

    PubMed

    Morita, T; Takeda, K; Okumura, K

    1990-03-01

    Using Chinese hamster ovary K1 cells, chromosomal aberration tests were carried out with formic acid, acetic acid and lactic acid, and the relationship between the pH of the medium and the clastogenic activity was examined. The medium used was Ham's F12 supplemented with 17 mM NaHCO3 and 10% fetal calf serum. All of these acids induced chromosomal aberrations at the initial pH of ca. 6.0 or below (about 10-14 mM of each acid) both with and without S9 mix. Exposure of cells to about pH 5.7 or below (about 12-16 mM of each acid) was found to be toxic. When the culture medium was first acidified with each of these acids and then neutralized to pH 6.4 or pH 7.2 with NaOH, no clastogenic activity was observed. Using F12 medium supplemented with 34 mM NaHCO3 as a buffer, no clastogenic activity was observed at doses up to 25 mM of these acids (initial pH 5.8-6.0). However, it was found that about 10% of the cells had aberrations at pH 5.7 or below (27.5-32.5 mM of each acid). Furthermore, when 30 mM HEPES was used as a buffer, chromosomal aberrations were not induced at doses up to 20 mM formic acid and acetic acid (initial pH 7.0-7.1), and at doses up to 30 mM lactic acid (initial pH 6.6). In the initial pH range of 6.4-6.7 (25-32.5 mM of each acid), chromosomal aberrations were observed. The above results show that these acids themselves are non-clastogenic, and the pseudo-positive reactions attributable to non-physiological pH could be eliminated by either neutralization of the treatment medium or enhancement of the buffering ability.

  6. Effects of acetic acid and lactic acid on physicochemical characteristics of native and cross-linked wheat starches.

    PubMed

    Majzoobi, Mahsa; Beparva, Paniz

    2014-03-15

    The effects of two common organic acids; lactic and acetic acids (150 mg/kg) on physicochemical properties of native and cross-linked wheat starches were investigated prior and after gelatinization. These acids caused formation of some cracks and spots on the granules. The intrinsic viscosity of both starches decreased in the presence of the acids particularly after gelatinization. Water solubility increased while water absorption reduced after addition of the acids. The acids caused reduction in gelatinization temperature and enthalpy of gelatinization of both starches. The starch gels became softer, less cohesive, elastic and gummy when acids were added. These changes may indicate the degradation of the starch molecules by the acids. Cross-linked wheat starch was more resistant to the acids. However, both starches became more susceptible to the acids after gelatinization. The effect of lactic acid on physicochemical properties of both starches before and after gelatinization was greater than acetic acid.

  7. The role of glass composition in the behaviour of glass acetic acid and glass lactic acid cements.

    PubMed

    Shahid, Saroash; Billington, R W; Pearson, G J

    2008-02-01

    Cements have recently been described, made from glass ionomer glass reacted with acetic and lactic acid instead of polymeric carboxylic acid. From their behaviour a theory relating to a possible secondary setting mechanism of glass ionomer has been adduced. However, only one glass (G338) was used throughout. In this study a much simpler glass ionomer glass (MP4) was compared with G338. This produced very different results. With acetic acid G338 formed cement which became resistant to water over a period of hours, as previously reported, MP4 formed cement which was never stable to water. With lactic acid G338 behaved similarly to G338 with acetic acid, again as reported, but MP4 produced a cement which was completely resistant to water at early exposure and unusually became slightly less resistant if exposure was delayed for 6 h or more. These findings indicate that the theories relating to secondary setting in glass ionomer maturation may need revision.

  8. Effect of pH and lactic or acetic acid on ethanol productivity by Saccharomyces cerevisiae in corn mash.

    PubMed

    Graves, Tara; Narendranath, Neelakantam V; Dawson, Karl; Power, Ronan

    2006-06-01

    The effects of lactic and acetic acids on ethanol production by Saccharomyces cerevisiae in corn mash, as influenced by pH and dissolved solids concentration, were examined. The lactic and acetic acid concentrations utilized were 0, 0.5, 1.0, 2.0, 3.0 and 4.0% w/v, and 0, 0.1, 0.2, 0.4, 0.8 and 1.6% w/v, respectively. Corn mashes (20, 25 and 30% dry solids) were adjusted to the following pH levels after lactic or acetic acid addition: 4.0, 4.5, 5.0 or 5.5 prior to yeast inoculation. Lactic acid did not completely inhibit ethanol production by the yeast. However, lactic acid at 4% w/v decreased (P<0.05) final ethanol concentration in all mashes at all pH levels. In 30% solids mash set at pH < or =5, lactic acid at 3% w/v reduced (P<0.05) ethanol production. In contrast, inhibition by acetic acid increased as the concentration of solids in the mash increased and the pH of the medium declined. Ethanol production was completely inhibited in all mashes set at pH 4 in the presence of acetic acid at concentrations > or =0.8% w/v. In 30% solids mash set at pH 4, final ethanol levels decreased (P<0.01) with only 0.1% w/v acetic acid. These results suggest that the inhibitory effects of lactic acid and acetic acid on ethanol production in corn mash fermentation when set at a pH of 5.0-5.5 are not as great as that reported thus far using laboratory media.

  9. Lactic acid as potential substitute of acetic acid for dissolution of chitosan: preharvest application to Butterhead lettuce.

    PubMed

    Goñi, María Gabriela; Tomadoni, Bárbara; Roura, Sara Inés; Moreira, María Del Rosario

    2017-03-01

    Chitosan must be dissolved in acid solution to activate its antimicrobial properties. The objectives of present study were to determine whether acetic and lactic acids used to dissolve chitosan would influence its effectiveness to control the native microflora of Butterhead lettuce at harvest and during postharvest storage (7-8 °C, 5 days). Chitosan was applied as a SINGLE DOSE (14, 10, 7, 3 or 0 days previous to harvest) or in SUCCESSIVE DOSES (at 14 + 10 + 7+3 + 0 days prior to harvest). Although chitosan in acetic acid showed antimicrobial activity, treated plants showed dried brown stains which significantly reduced sensorial quality. Chitosan in lactic acid applied in a SINGLE DOSE at harvest or in SUCCESSIVE DOSES reduced microbial counts of all populations at harvest without affecting sensorial quality. After postharvest storage, lettuce treated with SUCCESSIVE APPLICATIONS of chitosan in lactic acid presented significant reductions in the microbial populations compared with untreated sample (-2.02 log in yeast and molds, -1.83 log in total coliforms, -1.4 log CFU g(-1) in mesophilic bacteria and -1.1 log in psychrophilic bacteria). In conclusion, replacement of acetic by lactic acid did not affect the antimicrobial activity of chitosan, reducing microbial counts at harvest and after postharvest storage without affecting sensorial quality.

  10. A PCR assay for detection of acetic acid-tolerant lactic acid bacteria in acidic food products.

    PubMed

    Nakano, Shigeru; Matsumura, Atsushi; Yamada, Toshihiro

    2004-03-01

    A PCR assay for the detection of acetic acid-tolerant lactic acid bacteria in the genera of Lactobacillus and Pediococcus was developed in this study. Primers targeting the bacterial 16S rRNA gene were newly designed and used in this PCR assay. To determine the specificity of the assay, 56 different bacterial strains (of 33 genera), 2 fungi, 3 animals, and 4 plants were tested. Results were positive for most tested bacterial members of 16S rRNA gene-based phylogenetic groups (classified in the Lactobacillus casei and Pediococcus group), including Lactobacillus fructivorans, Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus plantarum, and Lactobacillus paracasei. For all other bacterial strains and eukaryote tested, results were negative. Bacterial DNA for PCR was prepared with a simple procedure with the use of Chelex 100 resin from culture after growth in deMan Rogosa Sharpe broth (pH 6.0). To test this PCR assay for the monitoring of the acetic acid-tolerant lactic acid bacteria, L. fructivorans was inoculated into several acidic food as an indicator. Before the PCR, the inoculation of 10 to 50 CFU of bacteria per g of food was followed by a 28-h enrichment culture step, and the PCR assay allowed the detection of bacterial cells. Including the enrichment culture step, the entire PCR detection process can be completed within 30 h.

  11. A peculiar stimulatory effect of acetic and lactic acid on growth and fermentative metabolism of Zygosaccharomyces bailii.

    PubMed

    Dang, T D T; Vermeulen, A; Ragaert, P; Devlieghere, F

    2009-05-01

    Stimulatory or protective effects of organic acids at low concentrations, e.g. acetic and lactic acid, on microorganisms have previously been reported. Especially in case of Zygosaccharomyces bailii, a peculiar growth stimulation by these two acids has recently been noticed. In order to elucidate this interesting phenomenon, growth and fermentative metabolism of Z. bailii was investigated in media with low pH (pH 4.0), high sugar (15% (w/v)) and different acetic and lactic acid concentrations. At both experimental temperatures (7 and 30 degrees C), a growth stimulation in the presence of 2.5% (v/v) lactic acid was observed. Furthermore at 7 degrees C, the yeast exhibited another unusual behaviour as it grew much faster in media containing 1.25% (v/v) acetic acid than in the control (without any acid). Production of fermentative metabolites was also increased together with the enhanced growth at both temperatures. These possible stimulatory effects of acetic and lactic acid should be taken into consideration when the acids are used at low doses for food preservative purpose. Presence of the acids may stimulate Z. bailii growth and fermentative metabolism, particularly at refrigeration temperature, consequently resulting in an earlier spoilage.

  12. Microarray-based transcriptome of Listeria monocytogenes adapted to sublethal concentrations of acetic acid, lactic acid, and hydrochloric acid.

    PubMed

    Tessema, Girum Tadesse; Møretrø, Trond; Snipen, Lars; Heir, Even; Holck, Askild; Naterstad, Kristine; Axelsson, Lars

    2012-09-01

    Listeria monocytogenes , an important foodborne pathogen, commonly encounters organic acids in food-related environments. The transcriptome of L. monocytogenes L502 was analyzed after adaptation to pH 5 in the presence of acetic acid, lactic acid, or hydrochloric acid (HCl) at 25 °C, representing a condition encountered in mildly acidic ready-to-eat food kept at room temperature. The acid-treated cells were compared with a reference culture with a pH of 6.7 at the time of RNA harvesting. The number of genes and magnitude of transcriptional responses were higher for the organic acids than for HCl. Protein coding genes described for low pH stress, energy transport and metabolism, virulence determinates, and acid tolerance response were commonly regulated in the 3 acid-stressed cultures. Interestingly, the transcriptional levels of histidine and cell wall biosynthetic operons were upregulated, indicating possible universal response against low pH stress in L. monocytogenes. The opuCABCD operon, coding proteins for compatible solutes transport, and the transcriptional regulator sigL were significantly induced in the organic acids, strongly suggesting key roles during organic acid stress. The present study revealed the complex transcriptional responses of L. monocytogenes towards food-related acidulants and opens the roadmap for more specific and in-depth future studies.

  13. Recycling of carbon dioxide and acetate as lactic acid by the hydrogen-producing bacterium Thermotoga neapolitana.

    PubMed

    d'Ippolito, Giuliana; Dipasquale, Laura; Fontana, Angelo

    2014-09-01

    The heterotrophic bacterium Thermotoga neapolitana produces hydrogen by fermentation of sugars. Under capnophilic (carbon dioxide requiring) conditions, the process is preferentially associated with the production of lactic acid, which, as shown herein, is synthesized by reductive carboxylation of acetyl coenzyme A. The enzymatic coupling is dependent on the carbon dioxide stimulated activity of heterotetrameric pyruvate:ferredoxin oxidoreductase. Under the same culture conditions, T. neapolitana also operates the unfavorable synthesis of lactic acid from an exogenous acetate supply. This process, which requires carbon dioxide (or carbonate) and an unknown electron donor, allows for the conversion of carbon dioxide into added-value chemicals without biomass deconstruction.

  14. Quantifying Effect of Lactic, Acetic, and Propionic Acids on Growth of Molds Isolated from Spoiled Bakery Products.

    PubMed

    Dagnas, Stéphane; Gauvry, Emilie; Onno, Bernard; Membré, Jeanne-Marie

    2015-09-01

    The combined effect of undissociated lactic acid (0 to 180 mmol/liter), acetic acid (0 to 60 mmol/liter), and propionic acid (0 to 12 mmol/liter) on growth of the molds Aspergillus niger, Penicillium corylophilum, and Eurotium repens was quantified at pH 3.8 and 25°C on malt extract agar acid medium. The impact of these acids on lag time for growth (λ) was quantified through a gamma model based on the MIC. The impact of these acids on radial growth rate (μ) was analyzed statistically through polynomial regression. Concerning λ, propionic acid exhibited a stronger inhibitory effect (MIC of 8 to 20 mmol/liter depending on the mold species) than did acetic acid (MIC of 23 to 72 mmol/liter). The lactic acid effect was null on E. repens and inhibitory on A. niger and P. corylophilum. These results were validated using independent sets of data for the three acids at pH 3.8 but for only acetic and propionic acids at pH 4.5. Concerning μ, the effect of acetic and propionic acids was slightly inhibitory for A. niger and P. corylophilum but was not significant for E. repens. In contrast, lactic acid promoted radial growth of all three molds. The gamma terms developed here for these acids will be incorporated in a predictive model for temperature, water activity, and acid. More generally, results for μ and λ will be used to identify and evaluate solutions for controlling bakery product spoilage.

  15. Minimal inhibitory concentrations of undissociated lactic, acetic, citric and propionic acid for Listeria monocytogenes under conditions relevant to cheese.

    PubMed

    Wemmenhove, Ellen; van Valenberg, Hein J F; Zwietering, Marcel H; van Hooijdonk, Toon C M; Wells-Bennik, Marjon H J

    2016-09-01

    Minimal inhibitory concentrations (MICs) of undissociated lactic acid were determined for six different Listeria monocytogenes strains at 30 °C and in a pH range of 4.2-5.8. Small increments in pH and acid concentrations were used to accurately establish the growth/no growth limits of L. monocytogenes for these acids. The MICs of undissociated lactic acid in the pH range of 5.2-5.8 were generally higher than at pH 4.6 for the different L. monocytogenes strains. The average MIC of undissociated lactic acid was 5.0 (SD 1.5) mM in the pH range 5.2-5.6, which is relevant to Gouda cheese. Significant differences in MICs of undissociated lactic acid were found between strains of L. monocytogenes at a given pH, with a maximum observed level of 9.0 mM. Variations in MICs were mostly due to strain variation. In the pH range 5.2-5.6, the MICs of undissociated lactic acid were not significantly different at 12 °C and 30 °C. The average MICs of undissociated acetic acid, citric acid, and propionic acid were 19.0 (SD 6.5) mM, 3.8 (SD 0.9) mM, and 11.0 (SD 6.3) mM, respectively, for the six L. monocytogenes strains tested in the pH range 5.2-5.6. Variations in MICs of these organic acids for L. monocytogenes were also mostly due to strain variation. The generated data contribute to improved predictions of growth/no growth of L. monocytogenes in cheese and other foods containing these organic acids.

  16. Sensitivity of acid-adapted and acid-shocked Shigella flexneri to reduced pH achieved with acetic, lactic, and propionic acids.

    PubMed

    Tetteh, G L; Beuchat, L R

    2001-07-01

    Survival and growth characteristics of unadapted, acid-adapted, and acid-shocked Shigella flexneri 2a cells in acidified (pH 3.5 to 5.5) tryptic soy broth with 0.25% glucose (TSB) and tryptic soy agar (TSA) were determined. S. flexneri was grown at 37 degrees C for 18 h in tryptic soy broth without glucose (TSBNG) (unadapted) and TSBNG supplemented with 1% glucose (TSBG) (acid-adapted). Cells grown in TSBNG were acid shocked by adjusting 16-h cultures to pH 5.05 +/- 0.05 with lactic acid. Cells were then inoculated into TSB acidified with acetic, lactic, or propionic acids to pH 5.5, 4.5, or 3.5 and incubated at 37 degrees C for 6 h. The order of lethality at a given pH was lactic acid < acetic acid < propionic acid. Significantly (P < or = 0.05) higher numbers of acid-adapted cells, compared to acid-shocked and unadapted cells, were recovered from TSB acidified (pH 3.5) with lactic or acetic acids. None of the cells survived a 30-min exposure in TSB acidified with propionic acid to pH 3.5. When the three cell types were plated on TSA acidified with lactic, acetic, or propionic acids at pH < or = 4.5, < or = 5.5, and < or = 5.5, respectively, visible colonies were not detected. Viable unadapted, acid-adapted, and acid-shocked cells were, however, recovered from TSA acidified with all three acids at pH > or = 4.5. Acid-adapted and, to a lesser extent, acid-shocked cells survived at lower pH than did unadapted cells, indicating that prior exposure to mild acidic environment results in increased acid resistance. Survival of S. flexneri at a given pH was influenced by the type of acidulant used, a response characteristic exhibited by other gram-negative enteric pathogens.

  17. Influence of acetic, citric, and lactic acids on Escherichia coli O157:H7 membrane lipid composition, verotoxin secretion, and acid resistance in simulated gastric fluid.

    PubMed

    Yuk, Hyun-Gyun; Marshall, Douglas L

    2005-04-01

    The effect of organic acid (acetic, citric, and lactic acids) adaptation at equivalent initial pH values (6.4 and 5.4) on changes in membrane lipid composition, verotoxin concentration, and acid resistance in simulated gastric fluid (pH 1.5, 37 degrees C) was determined for Escherichia coli O157:H7 ATCC 43895 (HEC) and an rpoS mutant of E. coli O157:H7 ATCC 43895 (RM, FRIK 816-3). For HEC, lactic acid-adapted (pH 5.4) cells had the greatest D-value (32.2 min) and acetic acid-adapted (pH 5.4) cells had the smallest D-value (16.6 min) in simulated gastric fluid. For RM, D-values of citric and acetic acid-adapted cells were similar to those for nonadapted cells grown at pH 7.3, but D-values increased from 13.1 to 27.9 min in lactic acid-adapted cells (from pH 7.3 to pH 5.4). For both strains, the ratio of cis-vaccenic to palmitic acids decreased for citric and lactic acid-adapted cells, but the ratio increased for acetic acid-adapted cells at pH 5.4. Organic acid-adapted cells produced less total verotoxin than did nonadapted cells at approximately 10(8) CFU/ml. Extracellular verotoxin concentration proportionally decreased with decreasing pH for both HEC and RM. Changes in membrane lipid composition, verotoxin concentration, and acid resistance in HEC and RM were dependent on both pH and organic acid. Deletion of the rpoS gene did not affect these changes but did decrease acid resistance in citric acid-adapted cells. Results indicate that decreased membrane fluidity may have caused increased acid resistance and decreased verotoxin secretion.

  18. Molecular identification and physiological characterization of yeasts, lactic acid bacteria and acetic acid bacteria isolated from heap and box cocoa bean fermentations in West Africa.

    PubMed

    Visintin, Simonetta; Alessandria, Valentina; Valente, Antonio; Dolci, Paola; Cocolin, Luca

    2016-01-04

    Yeast, lactic acid bacteria (LAB) and acetic acid bacteria (AAB) populations, isolated from cocoa bean heap and box fermentations in West Africa, have been investigated. The fermentation dynamicswere determined by viable counts, and 106 yeasts, 105 LAB and 82 AAB isolateswere identified by means of rep-PCR grouping and sequencing of the rRNA genes. During the box fermentations, the most abundant species were Saccharomyces cerevisiae, Candida ethanolica, Lactobacillus fermentum, Lactobacillus plantarum, Acetobacter pasteurianus and Acetobacter syzygii, while S. cerevisiae, Schizosaccharomyces pombe, Hanseniaspora guilliermondii, Pichia manshurica, C. ethanolica, Hanseniaspora uvarum, Lb. fermentum, Lb. plantarum, A. pasteurianus and Acetobacter lovaniensis were identified in the heap fermentations. Furthermore, the most abundant species were molecularly characterized by analyzing the rep-PCR profiles. Strains grouped according to the type of fermentations and their progression during the transformation process were also highlighted. The yeast, LAB and AAB isolates were physiologically characterized to determine their ability to grow at different temperatures, as well as at different pH, and ethanol concentrations, tolerance to osmotic stress, and lactic acid and acetic acid inhibition. Temperatures of 45 °C, a pH of 2.5 to 3.5, 12% (v/v) ethanol and high concentrations of lactic and acetic acid have a significant influence on the growth of yeasts, LAB and AAB. Finally, the yeastswere screened for enzymatic activity, and the S. cerevisiae, H. guilliermondii, H. uvarumand C. ethanolica species were shown to possess several enzymes that may impact the quality of the final product.

  19. Yeast genes involved in response to lactic acid and acetic acid: acidic conditions caused by the organic acids in Saccharomyces cerevisiae cultures induce expression of intracellular metal metabolism genes regulated by Aft1p.

    PubMed

    Kawahata, Miho; Masaki, Kazuo; Fujii, Tsutomu; Iefuji, Haruyuki

    2006-09-01

    Using two types of genome-wide analysis to investigate yeast genes involved in response to lactic acid and acetic acid, we found that the acidic condition affects metal metabolism. The first type is an expression analysis using DNA microarrays to investigate 'acid shock response' as the first step to adapt to an acidic condition, and 'acid adaptation' by maintaining integrity in the acidic condition. The other is a functional screening using the nonessential genes deletion collection of Saccharomyces cerevisiae. The expression analysis showed that genes involved in stress response, such as YGP1, TPS1 and HSP150, were induced under the acid shock response. Genes such as FIT2, ARN1 and ARN2, involved in metal metabolism regulated by Aft1p, were induced under the acid adaptation. AFT1 was induced under acid shock response and under acid adaptation with lactic acid. Moreover, green fluorescent protein-fused Aft1p was localized to the nucleus in cells grown in media containing lactic acid, acetic acid, or hydrochloric acid. Both analyses suggested that the acidic condition affects cell wall architecture. The depletion of cell-wall components encoded by SED1, DSE2, CTS1, EGT2, SCW11, SUN4 and YNL300W and histone acetyltransferase complex proteins encoded by YID21, EAF3, EAF5, EAF6 and YAF9 increased resistance to lactic acid. Depletion of the cell-wall mannoprotein Sed1p provided resistance to lactic acid, although the expression of SED1 was induced by exposure to lactic acid. Depletion of vacuolar membrane H+-ATPase and high-osmolarity glycerol mitogen-activated protein kinase proteins caused acid sensitivity. Moreover, our quantitative PCR showed that expression of PDR12 increased under acid shock response with lactic acid and decreased under acid adaptation with hydrochloric acid.

  20. Biodiversity of yeasts, lactic acid bacteria and acetic acid bacteria in the fermentation of "Shanxi aged vinegar", a traditional Chinese vinegar.

    PubMed

    Wu, Jia Jia; Ma, Ying Kun; Zhang, Fen Fen; Chen, Fu Sheng

    2012-05-01

    Shanxi aged vinegar is a famous traditional Chinese vinegar made from several kinds of cereal by spontaneous solid-state fermentation techniques. In order to get a comprehensive understanding of culturable microorganism's diversity present in its fermentation, the indigenous microorganisms including 47 yeast isolates, 28 lactic acid bacteria isolates and 58 acetic acid bacteria isolates were recovered in different fermenting time and characterized based on a combination of phenotypic and genotypic approaches including inter-delta/PCR, PCR-RFLP, ERIC/PCR analysis, as well as 16S rRNA and 26S rRNA partial gene sequencing. In the alcoholic fermentation, the dominant yeast species Saccharomyces (S.) cerevisiae (96%) exhibited low phenotypic and genotypic diversity among the isolates, while Lactobacillus (Lb.) fermentum together with Lb. plantarum, Lb. buchneri, Lb. casei, Pediococcus (P.) acidilactici, P. pentosaceus and Weissella confusa were predominated in the bacterial population at the same stage. Acetobacter (A.) pasteurianus showing great variety both in genotypic and phenotypic tests was the dominant species (76%) in the acetic acid fermentation stage, while the other acetic acid bacteria species including A. senegalensis, A. indonesiensis, A. malorum and A. orientalis, as well as Gluconobacter (G.) oxydans were detected at initial point of alcoholic and acetic acid fermentation stage respectively.

  1. Lactic acid test

    MedlinePlus

    Lactate test ... test. Exercise can cause a temporary increase in lactic acid levels. ... not getting enough oxygen. Conditions that can increase lactic acid levels include: Heart failure Liver disease Lung disease ...

  2. Modelling the unexpected effect of acetic and lactic acid in combination with pH and aw on the growth/no growth interface of Zygosaccharomyces bailii.

    PubMed

    Vermeulen, A; Dang, T D T; Geeraerd, A H; Bernaerts, K; Debevere, J; Van Impe, J; Devlieghere, F

    2008-05-10

    Microbial spoilage of shelf-stable acidified sauces is predominantly caused by lactic acid bacteria and yeasts. A specific spoilage yeast in these products is Zygosaccharomyces bailii, as this fructophilic, osmotolerant, and weak acid resistant yeast is difficult to control. A growth/no growth model was developed describing the influence of (i) pH in a range from pH 3.0 to pH 5.0 (5 levels), (ii) acetic acid in a range from 0 to 3.5% (w/v), and (iii) lactic acid in a range from 0 to 3.0% (w/v). aw was fixed at a level of 0.95 which is representative for acidified sauces with high sugar content. Modified Sabouraud medium was inoculated at +/- 10(4) CFU/ml, incubated at 30 degrees C and growth was assessed by optical density measurements. All combinations of environmental conditions were tested in at least twelve replicates, yielding precise values for the probability of growth. Results showed that replacing acetic acid by lactic acid, which has a milder taste, may imply some risks on food spoilage because, under some conditions, stimulation of growth by lactic acid was observed. This stimulation had also consequences on the model development: (i) only ordinary logistic regression models were able to describe this phenomenon due to their flexible behaviour, (ii) it was necessary to split up the data set into two subsets to have the best description of the obtained data. Two different ordinary logistic regression models were fitted on these data sets taking either the total acid concentration as one of the explanatory variables or differentiating between the undissociated and dissociated acid concentrations. The obtained models were compared with the CIMSCEE code [CIMSCEE, 1992. Code for the production of microbiologically safe and stable emulsified and non-emulsified sauces containing acetic acid. Comité des Industries des Mayonnaise et Sauces Condimentaires, de la Communauté Economique Européenne, Brussels, Belgium], a formula which is nowadays often used by the

  3. Flecainide acetate acetic acid solvates.

    PubMed

    Veldre, Kaspars; Actiņs, Andris; Eglite, Zane

    2011-02-01

    Flecainide acetate forms acetic acid solvates with 0.5 and 2 acetic acid molecules. Powder X-ray diffraction, differential thermal analysis/thermogravimetric, infrared, and potentiometric titration were used to determine the composition of solvates. Flecainide acetate hemisolvate with acetic acid decomposes to form a new crystalline form of flecainide acetate. This form is less stable than the already known polymorphic form at all temperatures, and it is formed due to kinetic reasons. Both flecainide acetate nonsolvated and flecainide acetate hemisolvate forms crystallize in monoclinic crystals, but flecainide triacetate forms triclinic crystals. Solvate formation was not observed when flecainide base was treated with formic acid, propanoic acid, and butanoic acid. Only nonsolvated flecainide salts were obtained in these experiments.

  4. Simultaneous determination of 4-hydroxyphenyl lactic acid, 4-hydroxyphenyl acetic acid, and 3-4-hydroxyphenyl propionic acid in human urine by Ultra high performance liquid chromatography with fluorescence detection.

    PubMed

    Yang, Yongli; Liu, Fan; Wan, Yiqun

    2017-03-27

    A simple and reliable method was established for simultaneous determination of 4-hydroxyphenyl acetic acid, 4-hydroxyphenyl lactic acid, and 3-4-hydroxyphenyl propionic acid in human urine by high-performance liquid chromatography with fluorescence detection. Solid-phase extraction was used to eliminate the interferences in urine. The separation of three analytes was achieved using a C18 column and a mobile phase formed by a 95:5 v/v mixture of 50 mmol/L ammonium acetate buffer at pH 6.8 that contained 5 mmol/L tetrabutyl ammonium bromide and acetonitrile. Under the optimized conditions, the detection limits of 4-hydroxyphenyl acetic acid, 4-hydroxyphenyl lactic acid, and 3-4-hydroxyphenyl propionic acid were 4.8 × 10(-3) , 8.80 × 10(-3) , and 9.00 × 10(-3) mg/L, respectively, and the recoveries were in the range of 85.0-120.0% with relative standard deviations of 1.5-3.1%. This method was used to analyze urine samples from breast cancer patients, healthy people and postsurgery breast cancer patients. Significant differences of urinary levels of 4-hydroxyphenyl acetic acid and 4-hydroxyphenyl lactic acid could be found between the breast cancer patients group and other two groups. No effect of age and sex was observed on the urinary levels of 4-hydroxyphenyl acetic acid and 4-hydroxyphenyl lactic acid. This method might be helpful for cancer biomarkers discovery in urine. This article is protected by copyright. All rights reserved.

  5. Influence of Turning and Environmental Contamination on the Dynamics of Populations of Lactic Acid and Acetic Acid Bacteria Involved in Spontaneous Cocoa Bean Heap Fermentation in Ghana▿

    PubMed Central

    Camu, Nicholas; González, Ángel; De Winter, Tom; Van Schoor, Ann; De Bruyne, Katrien; Vandamme, Peter; Takrama, Jemmy S.; Addo, Solomon K.; De Vuyst, Luc

    2008-01-01

    The influence of turning and environmental contamination on six spontaneous cocoa bean heap fermentations performed in Ghana was studied through a multiphasic approach, encompassing both microbiological (culture-dependent and culture-independent techniques) and metabolite target analyses. A sensory analysis of chocolate made from the fermented, dried beans was performed as well. Only four clusters were found among the isolates of acetic acid bacteria (AAB) identified: Acetobacter pasteurianus, Acetobacter ghanensis, Acetobacter senegalensis, and a potential new Acetobacter lovaniensis-like species. Two main clusters were identified among the lactic acid bacteria (LAB) isolated, namely, Lactobacillus plantarum and Lactobacillus fermentum. No differences in biodiversity of LAB and AAB were seen for fermentations carried out at the farm and factory sites, indicating the cocoa pod surfaces and not the general environment as the main inoculum for spontaneous cocoa bean heap fermentation. Turning of the heaps enhanced aeration and increased the relative population size of AAB and the production of acetic acid. This in turn gave a more sour taste to chocolate made from these beans. Bitterness was reduced through losses of polyphenols and alkaloids upon fermentation and cocoa bean processing. PMID:17993565

  6. Property tuning of poly(lactic acid)/cellulose bio-composites through blending with modified ethylene-vinyl acetate copolymer.

    PubMed

    Pracella, Mariano; Haque, Md Minhaz-Ul; Paci, Massimo; Alvarez, Vera

    2016-02-10

    The effect of addition of an ethylene-vinyl acetate copolymer modified with glycidyl methacrylate (EVA-GMA) on the structure and properties of poly(lactic acid) (PLA) composites with cellulose micro fibres (CF) was investigated. Binary (PLA/CF) and ternary (PLA/EVA-GMA/CF) composites obtained by melt mixing in Brabender mixer were analysed by SEM, POM, WAXS, DSC, TGA and tensile tests. The miscibility and morphology of PLA/EVA-GMA blends were first examined as a function of composition: a large rise of PLA spherulite growth rate in the blends was discovered with increasing the EVA-GMA content (0-30 wt%) in the isothermal crystallization both from the melt and the solid state. PLA/EVA-GMA/CF ternary composites displayed improved adhesion and dispersion of fibres into the matrix as compared to PLA/CF system. Marked changes of thermodynamic and tensile parameters, as elastic modulus, strength and elongation at break were observed for the composites, depending on blend composition, polymer miscibility and fibre-matrix chemical interactions at the interface.

  7. Vaginal concentrations of lactic acid potently inactivate HIV

    PubMed Central

    Aldunate, Muriel; Tyssen, David; Johnson, Adam; Zakir, Tasnim; Sonza, Secondo; Moench, Thomas; Cone, Richard; Tachedjian, Gilda

    2013-01-01

    Objectives When Lactobacillus spp. dominate the vaginal microbiota of women of reproductive age they acidify the vagina to pH <4.0 by producing ∼1% lactic acid in a nearly racemic mixture of d- and l-isomers. We determined the HIV virucidal activity of racemic lactic acid, and its d- and l-isomers, compared with acetic acid and acidity alone (by the addition of HCl). Methods HIV-1 and HIV-2 were transiently treated with acids in the absence or presence of human genital secretions at 37°C for different time intervals, then immediately neutralized and residual infectivity determined in the TZM-bl reporter cell line. Results l-lactic acid at 0.3% (w/w) was 17-fold more potent than d-lactic acid in inactivating HIVBa-L. Complete inactivation of different HIV-1 subtypes and HIV-2 was achieved with ≥0.4% (w/w) l-lactic acid. At a typical vaginal pH of 3.8, l-lactic acid at 1% (w/w) more potently and rapidly inactivated HIVBa-L and HIV-1 transmitter/founder strains compared with 1% (w/w) acetic acid and with acidity alone, all adjusted to pH 3.8. A final concentration of 1% (w/w) l-lactic acid maximally inactivated HIVBa-L in the presence of cervicovaginal secretions and seminal plasma. The anti-HIV activity of l-lactic acid was pH dependent, being abrogated at neutral pH, indicating that its virucidal activity is mediated by protonated lactic acid and not the lactate anion. Conclusions l-lactic acid at physiological concentrations demonstrates potent HIV virucidal activity distinct from acidity alone and greater than acetic acid, suggesting a protective role in the sexual transmission of HIV. PMID:23657804

  8. The effect of lactic acid bacteria on cocoa bean fermentation.

    PubMed

    Ho, Van Thi Thuy; Zhao, Jian; Fleet, Graham

    2015-07-16

    Cocoa beans (Theobroma cacao L.) are the raw material for chocolate production. Fermentation of cocoa pulp by microorganisms is crucial for developing chocolate flavor precursors. Yeasts conduct an alcoholic fermentation within the bean pulp that is essential for the production of good quality beans, giving typical chocolate characters. However, the roles of bacteria such as lactic acid bacteria and acetic acid bacteria in contributing to the quality of cocoa bean and chocolate are not fully understood. Using controlled laboratory fermentations, this study investigated the contribution of lactic acid bacteria to cocoa bean fermentation. Cocoa beans were fermented under conditions where the growth of lactic acid bacteria was restricted by the use of nisin and lysozyme. The resultant microbial ecology, chemistry and chocolate quality of beans from these fermentations were compared with those of indigenous (control) fermentations. The yeasts Hanseniaspora guilliermondii, Pichia kudriavzevii, Kluyveromyces marxianus and Saccharomyces cerevisiae, the lactic acid bacteria Lactobacillus plantarum, Lactobacillus pentosus and Lactobacillus fermentum and the acetic acid bacteria Acetobacter pasteurianus and Gluconobacter frateurii were the major species found in control fermentations. In fermentations with the presence of nisin and lysozyme, the same species of yeasts and acetic acid bacteria grew but the growth of lactic acid bacteria was prevented or restricted. These beans underwent characteristic alcoholic fermentation where the utilization of sugars and the production of ethanol, organic acids and volatile compounds in the bean pulp and nibs were similar for beans fermented in the presence of lactic acid bacteria. Lactic acid was produced during both fermentations but more so when lactic acid bacteria grew. Beans fermented in the presence or absence of lactic acid bacteria were fully fermented, had similar shell weights and gave acceptable chocolates with no differences

  9. Effect of gamma ray on poly(lactic acid)/poly(vinyl acetate-co-vinyl alcohol) blends as biodegradable food packaging films

    NASA Astrophysics Data System (ADS)

    Razavi, Seyed Mohammad; Dadbin, Susan; Frounchi, Masoud

    2014-03-01

    Poly(lactic acid) (PLA)/poly(vinyl acetate-co-vinyl alcohol) [P(VAc-co-VA)] blends as new transparent film packaging materials were prepared at various blend compositions and different vinyl alcohol contents. The blends and pure PLA were irradiated by gamma rays to investigate the extent of changes in the packaging material during gamma ray sterilization process. The miscibility of the blends was dependent on the blend composition and vinyl alcohol content; gamma irradiation had little effect on the extent of miscibility. The glass transition temperature of pure PLA and PLA/P(VAc-co-VA) miscible blends reduced after irradiation. On the other hand in PLA/P(VAc-co-VA) immiscible blends, while the glass transition temperature of the PLA phase decreased; that of the copolymer phase slightly increased. The reduction in the glass transition was about 10 percent for samples irradiated with 50 kGy indicating dominance of chain scission of PLA molecules at high irradiation dose. The latter was verified by drop in mechanical properties of pure PLA after exposing to gamma irradiation at 50 kGy. Blending of PLA with the copolymer P(VAc-co-VA) compensated greatly the adverse effects of irradiation on PLA. The oxygen-barrier property of the blend was superior to the neat PLA and remained almost intact with irradiation. The un-irradiated and irradiated blends had excellent transparency. Gamma ray doses used for sterilization purposes are usually less than 20 kGy. It was shown that gamma irradiation at 20 kGy had no or little adverse effects on PLA/P(VAc-co-VA) blends mechanical and gas barrier properties.

  10. Biopreservation by lactic acid bacteria.

    PubMed

    Stiles, M E

    1996-10-01

    Biopreservation refers to extended storage life and enhanced safety of foods using the natural microflora and (or) their antibacterial products. Lactic acid bacteria have a major potential for use in biopreservation because they are safe to consume and during storage they naturally dominate the microflora of many foods. In milk, brined vegetables, many cereal products and meats with added carbohydrate, the growth of lactic acid bacteria produces a new food product. In raw meats and fish that are chill stored under vacuum or in an environment with elevated carbon dioxide concentration, the lactic acid bacteria become the dominant population and preserve the meat with a "hidden' fermentation. The same applies to processed meats provided that the lactic acid bacteria survive the heat treatment or they are inoculated onto the product after heat treatment. This paper reviews the current status and potential for controlled biopreservation of foods.

  11. [Teichoic acids from lactic acid bacteria].

    PubMed

    Livins'ka, O P; Harmasheva, I L; Kovalenko, N K

    2012-01-01

    The current view of the structural diversity of teichoic acids and their involvement in the biological activity of lactobacilli has been reviewed. The mechanisms of effects of probiotic lactic acid bacteria, in particular adhesive and immunostimulating functions have been described. The prospects of the use of structure data of teichoic acid in the assessment of intraspecific diversity of lactic acid bacteria have been also reflected.

  12. Amylolytic bacterial lactic acid fermentation - a review.

    PubMed

    Reddy, Gopal; Altaf, Md; Naveena, B J; Venkateshwar, M; Kumar, E Vijay

    2008-01-01

    Lactic acid, an enigmatic chemical has wide applications in food, pharmaceutical, leather, textile industries and as chemical feed stock. Novel applications in synthesis of biodegradable plastics have increased the demand for lactic acid. Microbial fermentations are preferred over chemical synthesis of lactic acid due to various factors. Refined sugars, though costly, are the choice substrates for lactic acid production using Lactobacillus sps. Complex natural starchy raw materials used for production of lactic acid involve pretreatment by gelatinization and liquefaction followed by enzymatic saccharification to glucose and subsequent conversion of glucose to lactic acid by Lactobacillus fermentation. Direct conversion of starchy biomass to lactic acid by bacteria possessing both amylolytic and lactic acid producing character will eliminate the two step process to make it economical. Very few amylolytic lactic acid bacteria with high potential to produce lactic acid at high substrate concentrations are reported till date. In this view, a search has been made for various amylolytic LAB involved in production of lactic acid and utilization of cheaply available renewable agricultural starchy biomass. Lactobacillus amylophilus GV6 is an efficient and widely studied amylolytic lactic acid producing bacteria capable of utilizing inexpensive carbon and nitrogen substrates with high lactic acid production efficiency. This is the first review on amylolytic bacterial lactic acid fermentations till date.

  13. Acid hydrolysis of sugarcane bagasse for lactic acid production.

    PubMed

    Laopaiboon, Pattana; Thani, Arthit; Leelavatcharamas, Vichean; Laopaiboon, Lakkana

    2010-02-01

    In order to use sugarcane bagasse as a substrate for lactic acid production, optimum conditions for acid hydrolysis of the bagasse were investigated. After lignin extraction, the conditions were varied in terms of hydrochloric (HCl) or sulfuric (H(2)SO(4)) concentration (0.5-5%, v/v), reaction time (1-5h) and incubation temperature (90-120 degrees C). The maximum catalytic efficiency (E) was 10.85 under the conditions of 0.5% of HCl at 100 degrees C for 5h, which the main components (in gl(-1)) in the hydrolysate were glucose, 1.50; xylose, 22.59; arabinose, 1.29; acetic acid, 0.15 and furfural, 1.19. To increase yield of lactic acid production from the hydrolysate by Lactococcus lactis IO-1, the hydrolysate was detoxified through amberlite and supplemented with 7 g l(-1) of xylose and 7 g l(-1) of yeast extract. The main products (in gl(-1)) of the fermentation were lactic acid, 10.85; acetic acid, 7.87; formic acid, 6.04 and ethanol, 5.24.

  14. 21 CFR 582.1061 - Lactic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Lactic acid. 582.1061 Section 582.1061 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1061 Lactic acid. (a) Product. Lactic acid. (b) Conditions of use. This substance is...

  15. 21 CFR 582.1061 - Lactic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Lactic acid. 582.1061 Section 582.1061 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1061 Lactic acid. (a) Product. Lactic acid. (b) Conditions of use. This substance is...

  16. 21 CFR 582.1061 - Lactic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Lactic acid. 582.1061 Section 582.1061 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1061 Lactic acid. (a) Product. Lactic acid. (b) Conditions of use. This substance is...

  17. 21 CFR 582.1061 - Lactic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Lactic acid. 582.1061 Section 582.1061 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1061 Lactic acid. (a) Product. Lactic acid. (b) Conditions of use. This substance is...

  18. 21 CFR 582.1061 - Lactic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Lactic acid. 582.1061 Section 582.1061 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1061 Lactic acid. (a) Product. Lactic acid. (b) Conditions of use. This substance is...

  19. A continuous acetic acid system for polyacrylamide gel electrophoresis of gliadins and other prolamines.

    PubMed

    Clements, R L

    1988-02-01

    A polyacrylamide gel electrophoresis system buffered by acetic acid alone was developed for electrophoresis of prolamines. When applied to gliadin electrophoresis, the acetic acid system produces more bands than does a conventional aluminum lactate-lactic acid system (using 12% acrylamide gels). The acetic acid system is relatively simple, requiring a single buffer component that is universally available in high purity.

  20. Alteration of the phospho- or neutral lipid content and fatty acid composition in Listeria monocytogenes due to acid adaptation mechanisms for hydrochloric, acetic and lactic acids at pH 5.5 or benzoic acid at neutral pH.

    PubMed

    Mastronicolis, Sofia K; Berberi, Anita; Diakogiannis, Ioannis; Petrova, Evanthia; Kiaki, Irene; Baltzi, Triantafillia; Xenikakis, Polydoros

    2010-10-01

    This study provides a first approach to observe the effects on Listeria monocytogenes of cellular exposure to acid stress at low or neutral pH, notably how phospho- or neutral lipids are involved in this mechanism, besides the fatty acid profile alteration. A thorough investigation of the composition of polar and neutral lipids from L. monocytogenes grown at pH 5.5 in presence of hydrochloric, acetic and lactic acids, or at neutral pH 7.3 in presence of benzoic acid, is described relative to cells grown in acid-free medium. The results showed that only low pH values enhance the antimicrobial activity of an acid. We suggest that, irrespective of pH, the acid adaptation response will lead to a similar alteration in fatty acid composition [decreasing the ratio of branched chain/saturated straight fatty acids of total lipids], mainly originating from the neutral lipid class of adapted cultures. Acid adaptation in L. monocytogenes was correlated with a decrease in total lipid phosphorus and, with the exception of cells adapted to benzoic acid, this change in the amount of phosphorus reflected a higher content of the neutral lipid class. Upon acetic or benzoic acid stress the lipid phosphorus proportion was analysed in the main phospholipids present: cardiolipin, phosphatidylglycerol, phosphoaminolipid and phosphatidylinositol. Interestingly only benzoic acid had a dramatic effect on the relative quantities of these four phospholipids.

  1. Lactic acid oligomers (OLAs) as prodrug moieties.

    PubMed

    Kruse, J; Lachmann, B; Lauer, R; Eppacher, S; Noe, C R

    2013-02-01

    In this paper we propose the use of lactic acid oligomers (OLAs) as prodrug moieties. Two synthetic approaches are presented, on the one hand a non selective oligomerisation of lactic acid and on the other hand a block synthesis to tetramers of lactic acid. Dimers of lactic acid were investigated with respect to their plasma stability and their adsorption to albumine. Ibuprofen was chosen as the first drug for OLAylation. The ester 19 of LA(1)-ibuprofen was evaluated with respect to the degradation to human plasma and the adsorption to albumine. All results indicate that lactic acid oligomers are promising prodrug moieties.

  2. Process for the preparation of lactic acid and glyceric acid

    DOEpatents

    Jackson, James E [Haslett, MI; Miller, Dennis J [Okemos, MI; Marincean, Simona [Dewitt, MI

    2008-12-02

    Hexose and pentose monosaccharides are degraded to lactic acid and glyceric acid in an aqueous solution in the presence of an excess of a strongly anionic exchange resin, such as AMBERLITE IRN78 and AMBERLITE IRA400. The glyceric acid and lactic acid can be separated from the aqueous solution. Lactic acid and glyceric acid are staple articles of commerce.

  3. Degradation of organic acids by dairy lactic acid bacteria.

    PubMed

    Hegazi, F Z; Abo-Elnaga, I G

    1980-01-01

    One hundred and twelve different strains of lactic acid bacteria, belonging to the genera Leuconostoc, Streptococcus, and Lactobacillus, were examined for the ability to degrade 10 organic acids by detecting gas production, using the conventional Durham tube method. All the strains did not break down succinate, glutarate, 2-oxo-glutarate, and mucate. Malate, citrate, pyruvate, fumarate, tartrate, and gluconate were variably attacked. Streptococcus cremoiris AM2, ML8, and SK11 required glucose to produce gas from citrate, whereas Leuconostoc citrovorum and Streptococcus faecalis did not. Streptococcus cremoris differed from the other streptococci in not producing gas from gluconate. From all lactic acid bacteria examined, only Lactobacillus plantarum formed gas from tartarate. Determination of acetoin and diacetyl proved to be a more reliable evidence for assessing the degradation of pyruvate, compared with detection of gas production. Homofermentative lactobacilli and Leuconostoc citrovorum produced acetoin and diacetyl from pyruvate, whereas beta-bacteria did not, a character that would be of taxonomic value. Streptobacteria degraded pyruvate in the presence of glucose with lactate as the major product together with a mean acetate of 4.1%, ethanol 7.9%, acetoin 1.7%, and diacetyl 2.6% yield on a molar basis after 60 days at 30 degrees C. L. brevis produced acetate and lactate. Formation of diacetyl from pyruvate by lactic acid bacteria may play an important role in flavour development in fermenting dairy products, especially in cheese, where lactic acid bacteria usually predominate, and pyruvate is probably excreted in the breaking down of lactose and in the oxidative deamination of alanine by the accompanying microflora.

  4. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Lactic acid. 184.1061 Section 184.1061 Food and... Substances Affirmed as GRAS § 184.1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid,...

  5. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Lactic acid. 184.1061 Section 184.1061 Food and... Substances Affirmed as GRAS § 184.1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid,...

  6. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Lactic acid. 184.1061 Section 184.1061 Food and... Substances Affirmed as GRAS § 184.1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid,...

  7. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Lactic acid. 184.1061 Section 184.1061 Food and....1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid, occurs naturally in several foods. It...

  8. 21 CFR 184.1061 - Lactic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Lactic acid. 184.1061 Section 184.1061 Food and... Substances Affirmed as GRAS § 184.1061 Lactic acid. (a) Lactic acid (C3H6O3, CAS Reg. Nos.: dl mixture, 598-82-3; l-isomer, 79-33-4; d-isomer, 10326-41-7), the chemical 2-hydroxypropanoic acid,...

  9. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ....1450 Lactic acid test system. (a) Identification. A lactic acid test system is a device intended to measure lactic acid in whole blood and plasma. Lactic acid measurements that evaluate the acid-base status... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Lactic acid test system. 862.1450 Section...

  10. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ....1450 Lactic acid test system. (a) Identification. A lactic acid test system is a device intended to measure lactic acid in whole blood and plasma. Lactic acid measurements that evaluate the acid-base status... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Lactic acid test system. 862.1450 Section...

  11. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ....1450 Lactic acid test system. (a) Identification. A lactic acid test system is a device intended to measure lactic acid in whole blood and plasma. Lactic acid measurements that evaluate the acid-base status... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Lactic acid test system. 862.1450 Section...

  12. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Lactic acid test system. 862.1450 Section 862.1450....1450 Lactic acid test system. (a) Identification. A lactic acid test system is a device intended to measure lactic acid in whole blood and plasma. Lactic acid measurements that evaluate the acid-base...

  13. 21 CFR 862.1450 - Lactic acid test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Lactic acid test system. 862.1450 Section 862.1450....1450 Lactic acid test system. (a) Identification. A lactic acid test system is a device intended to measure lactic acid in whole blood and plasma. Lactic acid measurements that evaluate the acid-base...

  14. Genetics of Lactic Acid Bacteria

    NASA Astrophysics Data System (ADS)

    Zagorec, Monique; Anba-Mondoloni, Jamila; Coq, Anne-Marie Crutz-Le; Champomier-Vergès, Marie-Christine

    Many meat (or fish) products, obtained by the fermentation of meat originating from various animals by the flora that naturally contaminates it, are part of the human diet since millenaries. Historically, the use of bacteria as starters for the fermentation of meat, to produce dry sausages, was thus performed empirically through the endogenous micro-biota, then, by a volunteer addition of starters, often performed by back-slopping, without knowing precisely the microbial species involved. It is only since about 50 years that well defined bacterial cultures have been used as starters for the fermentation of dry sausages. Nowadays, the indigenous micro-biota of fermented meat products is well identified, and the literature is rich of reports on the identification of lactic acid bacteria (LAB) present in many traditional fermented products from various geographical origin, obtained without the addition of commercial starters (See Talon, Leroy, & Lebert, 2007, and references therein).

  15. Preservation of acidified cucumbers with a natural preservative combination of fumaric acid and allyl isothiocyanate that target lactic acid bacteria and yeasts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Without the addition of preservative compounds cucumbers acidified with 150 mM acetic acid with pH adjusted to 3.5 typically undergo fermentation by lactic acid bacteria. Fumaric acid (20 mM) inhibited growth of Lactobacillus plantarum and the lactic acid bacteria present on fresh cucumbers, but sp...

  16. Lignin poly(lactic acid) copolymers

    DOEpatents

    Olsson, Johan Vilhelm; Chung, Yi-Lin; Li, Russell Jingxian; Waymouth, Robert; Sattely, Elizabeth; Billington, Sarah; Frank, Curtis W.

    2017-02-14

    Provided herein are graft co-polymers of lignin and poly(lactic acid) (lignin-g-PLA copolymer), thermoset and thermoplastic polymers including them, methods of preparing these polymers, and articles of manufacture including such polymers.

  17. Effect of phenolic acids on glucose and organic acid metabolism by lactic acid bacteria from wine.

    PubMed

    Campos, Francisco M; Figueiredo, Ana R; Hogg, Tim A; Couto, José A

    2009-06-01

    The influence of phenolic (p-coumaric, caffeic, ferulic, gallic and protocatechuic) acids on glucose and organic acid metabolism by two strains of wine lactic acid bacteria (Oenococcus oeni VF and Lactobacillus hilgardii 5) was investigated. Cultures were grown in modified MRS medium supplemented with different phenolic acids. Cellular growth was monitored and metabolite concentrations were determined by HPLC-RI. Despite the strong inhibitory effect of most tested phenolic acids on the growth of O. oeni VF, the malolactic activity of this strain was not considerably affected by these compounds. While less affected in its growth, the capacity of L. hilgardii 5 to degrade malic acid was clearly diminished. Except for gallic acid, the addition of phenolic acids delayed the metabolism of glucose and citric acid in both strains tested. It was also found that the presence of hydroxycinnamic acids (p-coumaric, caffeic and ferulic) increased the yield of lactic and acetic acid production from glucose by O. oeni VF and not by L. hilgardii 5. The results show that important oenological characteristics of wine lactic acid bacteria, such as the malolactic activity and the production of volatile organic acids, may be differently affected by the presence of phenolic acids, depending on the bacterial species or strain.

  18. Fermentative production of L: -(+)-lactic acid by an alkaliphilic marine microorganism.

    PubMed

    Calabia, Buenaventurada P; Tokiwa, Yutaka; Aiba, Seiichi

    2011-07-01

    Of six strains of lactic acid-producing alkaliphilic microorganisms, Halolactibacillus halophilus was most efficient. It produced the highest concentration and yield of lactic acid, with minimal amounts of acetic and formic acid when sucrose and glucose were used as substrate. Mannose and xylose were poorly utilized. In batch fermentation at 30°C, pH 9 with 4 and 8% (w/v) sucrose, lactic acid was produced at 37.7 and 65.8 g l(-1), with yields of 95 and 83%, respectively. Likewise, when 4 and 8% (w/v) glucose were used, 33.4 and 59.6 g lactic acid l(-1) were produced with 85 and 76% yields, respectively. L: -(+)-lactic acid had an optical purity of 98.8% (from sucrose) and 98.3% (from glucose).

  19. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It...

  20. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  1. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  2. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  3. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  4. 21 CFR 582.1005 - Acetic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1005 Acetic acid. (a) Product. Acetic acid. (b) Conditions of use. This substance is...

  5. Lactic acid fermentation of crude sorghum extract

    SciTech Connect

    Samuel, W.A.; Lee, Y.Y.; Anthony, W.B.

    1980-04-01

    Crude extract from sweet sorghum supplemented with vetch juice was utilized as the carbohydrate source for fermentative production of lactic acid. Fermentation of media containing 7% (w/v) total sugar was completed in 60-80 hours by Lactobacillus plantarum, product yield averaging 85%. Maximum acid production rates were dependent on pH, initial substrate distribution, and concentration, the rates varying from 2 to 5 g/liter per hour. Under limited medium supplementation the lactic acid yield was lowered to 67%. The fermented ammoniated product contained over eight times as much equivalent crude protein (N x 6.25) as the original medium. Unstructured kinetic models were developed for cell growth, lactic acid formation, and substrate consumption in batch fermentation. With the provision of experimentally determined kinetic parameters, the proposed models accurately described the fermentation process. 15 references.

  6. Comparative genomics of the lactic acid bacteria

    SciTech Connect

    Makarova, K.; Slesarev, A.; Wolf, Y.; Sorokin, A.; Mirkin, B.; Koonin, E.; Pavlov, A.; Pavlova, N.; Karamychev, V.; Polouchine, N.; Shakhova, V.; Grigoriev, I.; Lou, Y.; Rokhsar, D.; Lucas, S.; Huang, K.; Goodstein, D. M.; Hawkins, T.; Plengvidhya, V.; Welker, D.; Hughes, J.; Goh, Y.; Benson, A.; Baldwin, K.; Lee, J. -H.; Diaz-Muniz, I.; Dosti, B.; Smeianov, V; Wechter, W.; Barabote, R.; Lorca, G.; Altermann, E.; Barrangou, R.; Ganesan, B.; Xie, Y.; Rawsthorne, H.; Tamir, D.; Parker, C.; Breidt, F.; Broadbent, J.; Hutkins, R.; O'Sullivan, D.; Steele, J.; Unlu, G.; Saier, M.; Klaenhammer, T.; Richardson, P.; Kozyavkin, S.; Weimer, B.; Mills, D.

    2006-06-01

    Lactic acid-producing bacteria are associated with various plant and animal niches and play a key role in the production of fermented foods and beverages. We report nine genome sequences representing the phylogenetic and functional diversity of these bacteria. The small genomes of lactic acid bacteria encode a broad repertoire of transporters for efficient carbon and nitrogen acquisition from the nutritionally rich environments they inhabit and reflect a limited range of biosynthetic capabilities that indicate both prototrophic and auxotrophic strains. Phylogenetic analyses, comparison of gene content across the group, and reconstruction of ancestral gene sets indicate a combination of extensive gene loss and key gene acquisitions via horizontal gene transfer during the coevolution of lactic acid bacteria with their habitats.

  7. Extractive fermentation of acetic acid

    SciTech Connect

    Busche, R.M.

    1991-12-31

    In this technoeconomic evaluation of the manufacture of acetic acid by fermentation, the use of the bacterium: Acetobacter suboxydans from the old vinegar process was compared with expected performance of the newer Clostridium thermoaceticum bacterium. Both systems were projected to operate as immobilized cells in a continuous, fluidized bed bioreactor, using solvent extraction to recover the product. Acetobacter metabolizes ethanol aerobically to produce acid at 100 g/L in a low pH medium. This ensures that the product is in the form of a concentrated extractable free acid, rather than as an unextractable salt. Unfortunately, yields from glucose by way of the ethanol fermentation are poor, but near the biological limits of the organisms involved. Conversely, C. thermoaceticum is a thermophilic anaerobe that operates at high fermentation rates on glucose at neutral pH to produce acetate salts directly in substantially quantitative yields. However, it is severely inhibited by product, which restricts concentration to a dilute 20 g/L. An improved Acetobacter system operating with recycled cells at 50 g/L appears capable of producing acid at $0.38/lb, as compared with a $0.29/lb price for synthetic acid. However, this system has only a limited margin for process improvement. The present Clostridium system cannot compete, since the required selling price would be $0.42/lb. However, if the organism could be adapted to tolerate higher product concentrations at acid pH, selling price could be reduced to $0.22/lb, or about 80% of the price of synthetic acid.

  8. Efficient production of l-lactic acid by an engineered Thermoanaerobacterium aotearoense with broad substrate specificity

    PubMed Central

    2013-01-01

    Background Efficient conversion of lignocellulosic biomass to optically pure lactic acid is a key challenge for the economical production of biodegradable poly-lactic acid. A recently isolated strain, Thermoanaerobacterium aotearoense SCUT27, is promising as an efficient lactic acid production bacterium from biomass due to its broad substrate specificity. Additionally, its strictly anaerobic and thermophilic characteristics suppress contamination from other microoragnisms. Herein, we report the significant improvements of concentration and yield in lactic acid production from various lignocellulosic derived sugars, achieved by the carbon flux redirection through homologous recombination in T. aotearoense SCUT27. Results T. aotearoense SCUT27 was engineered to block the acetic acid formation pathway to improve the lactic acid production. The genetic manipulation resulted in 1.8 and 2.1 fold increase of the lactic acid yield using 10 g/L of glucose or 10 g/L of xylose as substrate, respectively. The maximum l-lactic acid yield of 0.93 g/g glucose with an optical purity of 99.3% was obtained by the engineered strain, designated as LA1002, from 50 g/L of substrate, which is very close to the theoretical value (1.0 g/g of glucose). In particular, LA1002 produced lactic acid at an unprecedented concentration up to 3.20 g/L using 10 g/L xylan as the single substrate without any pretreatment after 48 h fermentation. The non-sterilized fermentative production of l-lactic acid was also carried out, achieving values of 44.89 g/L and 0.89 g/g mixed sugar for lactic acid concentration and yield, respectively. Conclusions Blocking acetic acid formation pathway in T. aotearoense SCUT27 increased l-lactic acid production and yield dramatically. To our best knowledge, this is the best performance of fermentation on lactic acid production using xylan as the sole carbon source, considering the final concentration, yield and fermentation time. In addition, it should be

  9. Efficient production of optically pure L-lactic acid from food waste at ambient temperature by regulating key enzyme activity.

    PubMed

    Li, Xiang; Chen, Yinguang; Zhao, Shu; Chen, Hong; Zheng, Xiong; Luo, Jinyang; Liu, Yanan

    2015-03-01

    Bio-production of optically pure L-lactic acid from food waste has attracted much interest as it can treat organic wastes with simultaneous recovery of valuable by-products. However, the yield of L-lactic acid was very low and no optically pure L-lactic acid was produced in the literature due to (1) the lower activity of enzymes involved in hydrolysis and L-lactic acid generation, and (2) the participation of other enzymes related to D-lactic acid and acetic and propionic acids production. In this paper, a new strategy was reported for effective production of optically pure L-lactic acid from food waste at ambient temperature, i.e. via regulating key enzyme activity by sewage sludge supplement and intermittent alkaline fermentation. It was found that not only optically pure L-lactic acid was produced, but the yield was enhanced by 2.89-fold. The mechanism study showed that the activities of enzymes relevant to food waste hydrolysis and lactic acid production were enhanced, and the key enzymes related to volatile fatty acids and D-lactic acid generations were severally decreased or inhibited. Also, the microbes responsible for L-lactic acid production were selectively proliferated. Finally, the pilot-scale continuous experiment was conducted to testify the feasibility of this new technique.

  10. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  11. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  12. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  13. 21 CFR 184.1005 - Acetic acid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Acetic acid. 184.1005 Section 184.1005 Food and... Substances Affirmed as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2H4O2, CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant and animal tissues. It is produced by fermentation...

  14. Precision genome engineering in lactic acid bacteria.

    PubMed

    van Pijkeren, Jan Peter; Britton, Robert A

    2014-08-29

    Innovative new genome engineering technologies for manipulating chromosomes have appeared in the last decade. One of these technologies, recombination mediated genetic engineering (recombineering) allows for precision DNA engineering of chromosomes and plasmids in Escherichia coli. Single-stranded DNA recombineering (SSDR) allows for the generation of subtle mutations without the need for selection and without leaving behind any foreign DNA. In this review we discuss the application of SSDR technology in lactic acid bacteria, with an emphasis on key factors that were critical to move this technology from E. coli into Lactobacillus reuteri and Lactococcus lactis. We also provide a blueprint for how to proceed if one is attempting to establish SSDR technology in a lactic acid bacterium. The emergence of CRISPR-Cas technology in genome engineering and its potential application to enhancing SSDR in lactic acid bacteria is discussed. The ability to perform precision genome engineering in medically and industrially important lactic acid bacteria will allow for the genetic improvement of strains without compromising safety.

  15. Why engineering lactic acid bacteria for biobutanol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Gram-positive Lactic acid bacteria (LAB) are considered attractive biocatalysts for biomass to biofuels for several reasons. They have GRAS (Generally Recognized As Safe) status that are acceptable in food, feed, and medical applications. LAB are fermentative: selected strains are capable of f...

  16. Precision genome engineering in lactic acid bacteria

    PubMed Central

    2014-01-01

    Innovative new genome engineering technologies for manipulating chromosomes have appeared in the last decade. One of these technologies, recombination mediated genetic engineering (recombineering) allows for precision DNA engineering of chromosomes and plasmids in Escherichia coli. Single-stranded DNA recombineering (SSDR) allows for the generation of subtle mutations without the need for selection and without leaving behind any foreign DNA. In this review we discuss the application of SSDR technology in lactic acid bacteria, with an emphasis on key factors that were critical to move this technology from E. coli into Lactobacillus reuteri and Lactococcus lactis. We also provide a blueprint for how to proceed if one is attempting to establish SSDR technology in a lactic acid bacterium. The emergence of CRISPR-Cas technology in genome engineering and its potential application to enhancing SSDR in lactic acid bacteria is discussed. The ability to perform precision genome engineering in medically and industrially important lactic acid bacteria will allow for the genetic improvement of strains without compromising safety. PMID:25185700

  17. Photoautotrophic production of D-lactic acid in an engineered cyanobacterium

    PubMed Central

    2013-01-01

    Background The world faces the challenge to develop sustainable technologies to replace thousands of products that have been generated from fossil fuels. Microbial cell factories serve as promising alternatives for the production of diverse commodity chemicals and biofuels from renewable resources. For example, polylactic acid (PLA) with its biodegradable properties is a sustainable, environmentally friendly alternative to polyethylene. At present, PLA microbial production is mainly dependent on food crops such as corn and sugarcane. Moreover, optically pure isomers of lactic acid are required for the production of PLA, where D-lactic acid controls the thermochemical and physical properties of PLA. Henceforth, production of D-lactic acid through a more sustainable source (CO2) is desirable. Results We have performed metabolic engineering on Synechocystis sp. PCC 6803 for the phototrophic synthesis of optically pure D-lactic acid from CO2. Synthesis of optically pure D-lactic acid was achieved by utilizing a recently discovered enzyme (i.e., a mutated glycerol dehydrogenase, GlyDH*). Significant improvements in D-lactic acid synthesis were achieved through codon optimization and by balancing the cofactor (NADH) availability through the heterologous expression of a soluble transhydrogenase. We have also discovered that addition of acetate to the cultures improved lactic acid production. More interestingly, 13C-pathway analysis revealed that acetate was not used for the synthesis of lactic acid, but was mainly used for synthesis of certain biomass building blocks (such as leucine and glutamate). Finally, the optimal strain was able to accumulate 1.14 g/L (photoautotrophic condition) and 2.17 g/L (phototrophic condition with acetate) of D-lactate in 24 days. Conclusions We have demonstrated the photoautotrophic production of D-lactic acid by engineering a cyanobacterium Synechocystis 6803. The engineered strain shows an excellent D-lactic acid productivity from CO2. In

  18. Synovial fluid lactic acid levels in septic arthritis.

    PubMed

    Riley, T V

    1981-01-01

    Synovial fluid lactic acid estimations were carried out on 50 samples by gas liquid chromatography. Specimens from 4 patients with bacteria arthritis, other than gonococcal, had a mean lactic acid concentration of 215 mg/dl. One patient with gonococcal arthritis had a synovial fluid lactic acid of 30 mg/dl. Forty-one patients with inflammatory arthritis and 4 patients with degenerative arthritis had mean synovial fluid lactic acid levels of 27 and 23 mg/dl respectively. The estimation of synovial fluid lactic acid is reliable in differentiating septic arthritis from inflammatory and degenerative arthritis except when the infecting organism is NEisseria gonorrhoeae.

  19. Distribution of D-amino acids in vinegars and involvement of lactic acid bacteria in the production of D-amino acids.

    PubMed

    Mutaguchi, Yuta; Ohmori, Taketo; Akano, Hirofumi; Doi, Katsumi; Ohshima, Toshihisa

    2013-01-01

    Levels of free D-amino acids were compared in 11 vinegars produced from different sources or through different manufacturing processes. To analyze the D- and L-amino acids, the enantiomers were initially converted into diastereomers using pre-column derivatization with o-phthaldialdehyde plus N-acethyl-L-cysteine or N-tert-butyloxycarbonyl-L-cysteine. This was followed by separation of the resultant fluorescent isoindol derivatives on an octadecylsilyl stationary phase using ultra-performance liquid chromatography. The analyses showed that the total D-amino acid level in lactic fermented tomato vinegar was very high. Furthermore, analysis of the amino acids in tomato juice samples collected after alcoholic, lactic and acetic fermentation during the production of lactic fermented tomato vinegar showed clearly that lactic fermentation is responsible for the D-amino acids production; marked increases in D-amino acids were seen during lactic fermentation, but not during alcoholic or acetic fermentation. This suggests lactic acid bacteria have a greater ability to produce D-amino acids than yeast or acetic acid bacteria.

  20. Vesicles protect activated acetic acid.

    PubMed

    Todd, Zoe R; House, Christopher H

    2014-10-01

    Abstract Methyl thioacetate, or activated acetic acid, has been proposed to be central to the origin of life and an important energy currency molecule in early cellular evolution. We have investigated the hydrolysis of methyl thioacetate under various conditions. Its uncatalyzed rate of hydrolysis is about 3 orders of magnitude faster (K=0.00663 s(-1); 100°C, pH 7.5, concentration=0.33 mM) than published rates for its catalyzed production, making it unlikely to accumulate under prebiotic conditions. However, our experiments showed that methyl thioacetate was protected from hydrolysis when inside its own hydrophobic droplets. Further, we found that methyl thioacetate protection from hydrolysis was also possible in droplets of hexane and in the membranes of nonanoic acid vesicles. Thus, the hydrophobic regions of prebiotic vesicles and early cell membranes could have offered a refuge for this energetic molecule, increasing its lifetime in close proximity to the reactions for which it would be needed. This model of early energy storage evokes an additional critical function for the earliest cell membranes.

  1. Impacts of lignocellulose-derived inhibitors on L-lactic acid fermentation by Rhizopus oryzae.

    PubMed

    Zhang, Li; Li, Xin; Yong, Qiang; Yang, Shang-Tian; Ouyang, Jia; Yu, Shiyuan

    2016-03-01

    Inhibitors generated in the pretreatment and hydrolysis of corn stover and corn cob were identified. In general, they inhibited cell growth, lactate dehydrogenase, and lactic acid production but with less or no adverse effect on alcohol dehydrogenase and ethanol production in batch fermentation by Rhizopus oryzae. Furfural and 5-hydroxymethyl furfural (HMF) were highly toxic at 0.5-1 g L(-1), while formic and acetic acids at less than 4 g L(-1) and levulinic acid at 10 g L(-1) were not toxic. Among the phenolic compounds at 1 g L(-1), trans-cinnamic acid and syringaldehyde had the highest toxicity while syringic, ferulic and p-coumaric acids were not toxic. Although these inhibitors were present at concentrations much lower than their separately identified toxic levels, lactic acid fermentation with the hydrolysates showed much inferior performance compared to the control without inhibitor, suggesting synergistic or compounded effects of the lignocellulose-degraded compounds on inhibiting lactic acid fermentation.

  2. Electron transfer induced fragmentation of acetic acid

    NASA Astrophysics Data System (ADS)

    Ferreira da Silva, F.; Meneses, G.; Almeida, D.; Limão-Vieira, P.

    2014-04-01

    We present negative ion formation driven by electron transfer in atom (K) molecule (acetic acid) collisions. Acetic acid has been found in the interstellar medium, is also considered a biological related compound and as such studying low energy electron interactions will bring new insights as far as induced chemistry is concerned.

  3. Production of lactic acid from hemicellulose extracts by Bacillus coagulans MXL-9.

    PubMed

    Walton, Sara L; Bischoff, Kenneth M; van Heiningen, Adriaan R P; van Walsum, G Peter

    2010-08-01

    Bacillus coagulans MXL-9 was found capable of growing on pre-pulping hemicellulose extracts, utilizing all of the principle monosugars found in woody biomass. This organism is a moderate thermophile isolated from compost for its pentose-utilizing capabilities. It was found to have high tolerance for inhibitors such as acetic acid and sodium, which are present in pre-pulping hemicellulose extracts. Fermentation of 20 g/l xylose in the presence of 30 g/l acetic acid required a longer lag phase but overall lactic acid yield was not diminished. Similarly, fermentation of xylose in the presence of 20 g/l sodium increased the lag time but did not affect overall product yield, though 30 g/l sodium proved completely inhibitory. Fermentation of hot water-extracted Siberian larch containing 45 g/l total monosaccharides, mainly galactose and arabinose, produced 33 g/l lactic acid in 60 h and completely consumed all sugars. Small amounts of co-products were formed, including acetic acid, formic acid, and ethanol. Hemicellulose extract formed during autohydrolysis of mixed hardwoods contained mainly xylose and was converted into lactic acid with a 94% yield. Green liquor-extracted hardwood hemicellulose containing 10 g/l acetic acid and 6 g/l sodium was also completely converted into lactic acid at a 72% yield. The Bacillus coagulans MXL-9 strain was found to be well suited to production of lactic acid from lignocellulosic biomass due to its compatibility with conditions favorable to industrial enzymes and its ability to withstand inhibitors while rapidly consuming all pentose and hexose sugars of interest at high product yields.

  4. [Bacteriocins produced by lactic acid bacteria].

    PubMed

    Bilková, Andrea; Sepova, Hana Kinová; Bilka, Frantisek; Balázová, Andrea

    2011-04-01

    Lactic acid bacteria comprise several genera of gram-positive bacteria that are known for the production of structurally different antimicrobial substances. Among them, bacteriocins are nowadays in the centre of scientific interest. Bacteriocins, proteinaceous antimicrobial substances, are produced ribosomally and have usually a narrow spectrum of bacterial growth inhibition. According to their structure and the target of their activity, they are divided into four classes, although there are some suggestions for a renewed classification. The most interesting and usable class are lantibiotics. They comprise the most widely commercially used and well examined bacteriocin, nisin. The non-pathogenic character of lactic acid bacteria is advantageous for using their bacteriocins in food preservation as well as in feed supplements or in veterinary medicine.

  5. Photocurable bioadhesive based on lactic acid.

    PubMed

    Marques, D S; Santos, J M C; Ferreira, P; Correia, T R; Correia, I J; Gil, M H; Baptista, C M S G

    2016-01-01

    Novel photocurable and low molecular weight oligomers based on l-lactic acid with proven interest to be used as bioadhesive were successfully manufactured. Preparation of lactic acid oligomers with methacrylic end functionalizations was carried out in the absence of catalyst or solvents by self-esterification in two reaction steps: telechelic lactic acid oligomerization with OH end groups and further functionalization with methacrylic anhydride. The final adhesive composition was achieved by the addition of a reported biocompatible photoinitiator (Irgacure® 2959). Preliminary in vitro biodegradability was investigated by hydrolytic degradation in PBS (pH=7.4) at 37 °C. The adhesion performance was evaluated using glued aminated substrates (gelatine pieces) subjected to pull-to-break test. Surface energy measured by contact angles is lower than the reported values of the skin and blood. The absence of cytoxicity was evaluated using human fibroblasts. A notable antimicrobial behaviour was observed using two bacterial models (Staphylococcus aureus and Escherichia coli). The cured material exhibited a strong thrombogenic character when placed in contact with blood, which can be predicted as a haemostatic effect for bleeding control. This novel material was subjected to an extensive characterization showing great potential for bioadhesive or other biomedical applications where biodegradable and biocompatible photocurable materials are required.

  6. Utilization of renewables for lactic acid fermentation.

    PubMed

    Venus, Joachim

    2006-12-01

    Originally, lactic acid was produced from pure substrates like glucose. Increasingly, however, agricultural feedstocks such as grains and green biomass are also being used as raw materials for the biotechnological production of lactic acid. A high-productivity lactic acid bacterium strain was selected, process parameters were optimized for the batch fermentation on a laboratory scale, and its performance at cultivation on a barley hydrolysate medium together with different supplements was examined. The present results for the cultivation of the Lactobacillus paracasei on complex nutrient broth are in the same range as those for another strain of the same species with pure glucose, de Man, Rogosa and Sharpe medium (MRS) minerals, peptone and yeast extract. Under these conditions, this strain was able to accumulate more than 100 g lactate/L in the MRS medium. Medium optimization experiments showed that the main part of the nitrogen-containing nutrients in the medium (peptone, yeast extract) can be replaced by protein extracts from green biomass (lucerne green juice). The green juice after pressing fresh biomass contains a series of nitrogen-containing compounds and inorganic salts, which are essential for cell growth. Thus, on laboratory scale, we have demonstrated that it is possible to substitute synthetic nutrients by renewable resources like cereals and green biomass without any loss of productivity. This high biomass concentration together with the number of living cells could increase the productivity to higher levels compared to the well-adapted synthetic nutrients of MRS.

  7. Poly(ethylene glycol) (PEG)-lactic acid nanocarrier-based degradable hydrogels for restoring the vaginal microenvironment.

    PubMed

    Sundara Rajan, Sujata; Turovskiy, Yevgeniy; Singh, Yashveer; Chikindas, Michael L; Sinko, Patrick J

    2014-11-28

    Women with bacterial vaginosis (BV) display reduced vaginal acidity, which make them susceptible to associated infections such as HIV. In the current study, poly(ethylene glycol) (PEG) nanocarrier-based degradable hydrogels were developed for the controlled release of lactic acid in the vagina of BV-infected women. PEG-lactic acid (PEG-LA) nanocarriers were prepared by covalently attaching lactic acid to 8-arm PEG-SH via cleavable thioester bonds. PEG-LA nanocarriers with 4 copies of lactic acid per molecule provided controlled release of lactic acid with a maximum release of 23% and 47% bound lactic acid in phosphate buffered saline (PBS, pH7.4) and acetate buffer (AB, pH4.3), respectively. The PEG nanocarrier-based hydrogels were formed by cross-linking the PEG-LA nanocarriers with 4-arm PEG-NHS via degradable thioester bonds. The nanocarrier-based hydrogels formed within 20 min under ambient conditions and exhibited an elastic modulus that was 100-fold higher than the viscous modulus. The nanocarrier-based degradable hydrogels provided controlled release of lactic acid for several hours; however, a maximum release of only 10%-14% bound lactic acid was observed possibly due to steric hindrance of the polymer chains in the cross-linked hydrogel. In contrast, hydrogels with passively entrapped lactic acid showed burst release with complete release within 30 min. Lactic acid showed antimicrobial activity against the primary BV pathogen Gardnerella vaginalis with a minimum inhibitory concentration (MIC) of 3.6 mg/ml. In addition, the hydrogels with passively entrapped lactic acid showed retained antimicrobial activity with complete inhibition G. vaginalis growth within 48 h. The results of the current study collectively demonstrate the potential of PEG nanocarrier-based hydrogels for vaginal administration of lactic acid for preventing and treating BV.

  8. Key volatile aroma compounds of lactic acid fermented malt based beverages - impact of lactic acid bacteria strains.

    PubMed

    Nsogning Dongmo, Sorelle; Sacher, Bertram; Kollmannsberger, Hubert; Becker, Thomas

    2017-08-15

    This study aims to define the aroma composition and key aroma compounds of barley malt wort beverages produced from fermentation using six lactic acid bacteria (LAB) strains. Gas chromatography mass spectrometry-olfactometry and flame ionization detection was employed; key aroma compounds were determined by means of aroma extract dilution analysis. Fifty-six detected volatile compounds were similar among beverages. However, significant differences were observed in the concentration of individual compounds. Key aroma compounds (flavor dilution (FD) factors ≥16) were β-damascenone, furaneol, phenylacetic acid, 2-phenylethanol, 4-vinylguaiacol, sotolon, methional, vanillin, acetic acid, nor-furaneol, guaiacol and ethyl 2-methylbutanoate. Furthermore, acetaldehyde had the greatest odor activity value of up to 4266. Sensory analyses revealed large differences in the flavor profile. Beverage from L. plantarum Lp. 758 showed the highest FD factors in key aroma compounds and was correlated to fruity flavors. Therefore, we suggest that suitable LAB strain selection may improve the flavor of malt based beverages.

  9. Conversion of Aqueous Ammonia-Treated Corn Stover to Lactic Acid by Simultaneous Saccharification and Cofermentation

    NASA Astrophysics Data System (ADS)

    Zhu, Yongming; Lee, Y. Y.; Elander, Richard T.

    Treatment of corn stover with aqueous ammonia removes most of the structural lignin, whereas retaining the majority of the carbohydrates in the solids. After treatment, both the cellulose and hemicellulose in corn stover become highly susceptible to enzymatic digestion. In this study, corn stover treated by aqueous ammonia was investigated as the substrate for lactic acid production by simultaneous saccharification and cofermentation (SSCF). A commercial cellulase (Spezyme-CP) and Lactobacillus pentosus American Type Culture Collection (ATCC) 8041 (Spanish Type Culture Collection [CECT]-4023) were used for hydrolysis and fermentation, respectively. In batch SSCF operation, the carbohydrates in the treated corn stover were converted to lactic acid with high yields, the maximum lactic acid yield reaching 92% of the stoichiometric maximum based on total fermentable carbohydrates (glucose, xylose, and arabinose). A small amount of acetic acid was also produced from pentoses through the phosphoketolase pathway. Among the major process variables for batch SSCF, enzyme loading and the amount of yeast extract were found to be the key factors affecting lactic acid production. Further tests on nutrients indicated that corn steep liquor could be substituted for yeast extract as a nitrogen source to achieve the same lactic acid yield. Fed-batch operation of the SSCF was beneficial in raising the concentration of lactic acid to a maximum value of 75.0 g/L.

  10. Technological and economic potential of poly(lactic acid) and lactic acid derivatives

    SciTech Connect

    Datta, R.; Tsai, S.P.; Bonsignore, P.; Moon, S.H.; Frank, J.R.

    1993-10-01

    Lactic acid has been an intermediate-volume specialty chemical (world production {approximately}40,000 tons/yr) used in a wide range of food processing and industrial applications. lactic acid h,as the potential of becoming a very large volume, commodity-chemical intermediate produced from renewable carbohydrates for use as feedstocks for biodegradable polymers, oxygenated chemicals, plant growth regulators, environmentally friendly ``green`` solvents, and specially chemical intermediates. In the past, efficient and economical technologies for the recovery and purification of lactic acid from crude fermentation broths and the conversion of tactic acid to the chemical or polymer intermediates had been the key technology impediments and main process cost centers. The development and deployment of novel separations technologies, such as electrodialysis (ED) with bipolar membranes, extractive distillations integrated with fermentation, and chemical conversion, can enable low-cost production with continuous processes in large-scale operations. The use of bipolar ED can virtually eliminate the salt or gypsum waste produced in the current lactic acid processes. In this paper, the recent technical advances in tactic and polylactic acid processes are discussed. The economic potential and manufacturing cost estimates of several products and process options are presented. The technical accomplishments at Argonne National Laboratory (ANL) and the future directions of this program at ANL are discussed.

  11. Recent advances in lactic acid production by microbial fermentation processes.

    PubMed

    Abdel-Rahman, Mohamed Ali; Tashiro, Yukihiro; Sonomoto, Kenji

    2013-11-01

    Fermentative production of optically pure lactic acid has roused interest among researchers in recent years due to its high potential for applications in a wide range of fields. More specifically, the sharp increase in manufacturing of biodegradable polylactic acid (PLA) materials, green alternatives to petroleum-derived plastics, has significantly increased the global interest in lactic acid production. However, higher production costs have hindered the large-scale application of PLA because of the high price of lactic acid. Therefore, reduction of lactic acid production cost through utilization of inexpensive substrates and improvement of lactic acid production and productivity has become an important goal. Various methods have been employed for enhanced lactic acid production, including several bioprocess techniques facilitated by wild-type and/or engineered microbes. In this review, we will discuss lactic acid producers with relation to their fermentation characteristics and metabolism. Inexpensive fermentative substrates, such as dairy products, food and agro-industrial wastes, glycerol, and algal biomass alternatives to costly pure sugars and food crops are introduced. The operational modes and fermentation methods that have been recently reported to improve lactic acid production in terms of concentrations, yields, and productivities are summarized and compared. High cell density fermentation through immobilization and cell-recycling techniques are also addressed. Finally, advances in recovery processes and concluding remarks on the future outlook of lactic acid production are presented.

  12. The Acetic Acid Tolerance Response induces cross-protection to salt stress in Salmonella typhimurium.

    PubMed

    Greenacre, E J; Brocklehurst, T F

    2006-10-15

    Salmonella typhimurium induces an Acid Tolerance Response (ATR) upon exposure to mildly acidic conditions in order to protect itself against severe acid shock. This response can also induce cross-protection to other stresses such as heat and salt. We investigated whether both the acetic acid induced and lactic acid induced ATR in S. typhimurium provided cross-protection to a salt stress at 20 degrees C. Acid-adapted cells were challenged with both a sodium chloride (NaCl) and potassium chloride (KCl) shock and their ability to survive ascertained. Acetic acid adaptation provided cells with protection against both NaCl and KCl stress. However, lactic acid adaptation did not protect against either osmotic stressor and rendered cells hypersensitive to NaCl. These results have implications for the food industry where hurdle technology means multiple sub-lethal stresses such as mild pH and low salt are commonly used in the preservation of products.

  13. Lactic acid bacteria as probiotics.

    PubMed

    Ljungh, Asa; Wadström, Torkel

    2006-09-01

    A number of Lactobacillus species, Bifidobacterium sp, Saccharomyces boulardii, and some other microbes have been proposed as and are used as probiotic strains, i.e. live microorganisms as food supplement in order to benefit health. The health claims range from rather vague as regulation of bowel activity and increasing of well-being to more specific, such as exerting antagonistic effect on the gastroenteric pathogens Clostridium difficile, Campylobacter jejuni, Helicobacter pylori and rotavirus, neutralising food mutagens produced in colon, shifting the immune response towards a Th2 response, and thereby alleviating allergic reactions, and lowering serum cholesterol (Tannock, 2002). Unfortunately, most publications are case reports, uncontrolled studies in humans, or reports of animal or in vitro studies. Whether or not the probiotic strains employed shall be of human origin is a matter of debate but this is not a matter of concern, as long as the strains can be shown to survive the transport in the human gastrointestinal (GI) tract and to colonise the human large intestine. This includes survival in the stressful environment of the stomach - acidic pH and bile - with induction of new genes encoding a number of stress proteins. Since the availability of antioxidants decreases rostrally in the GI tract production of antioxidants by colonic bacteria provides a beneficial effect in scavenging free radicals. LAB strains commonly produce antimicrobial substance(s) with activity against the homologous strain, but LAB strains also often produce microbicidal substances with effect against gastric and intestinal pathogens and other microbes, or compete for cell surface and mucin binding sites. This could be the mechanism behind reports that some probiotic strains inhibit or decrease translocation of bacteria from the gut to the liver. A protective effect against cancer development can be ascribed to binding of mutagens by intestinal bacteria, reduction of the enzymes beta

  14. Beneficial effects of lactic acid bacteria on human beings.

    PubMed

    Masood, Muhammad Irfan; Qadir, Muhammad Imran; Shirazi, Jafir Hussain; Khan, Ikram Ullah

    2011-02-01

    Lactic acid bacteria are a diverse group of bacteria that produce lactic acid as their major fermented product. Most of them are normal flora of human being and animals and produce myriad beneficial effects for human beings include, alleviation of lactose intolerance, diarrhea, peptic ulcer, stimulation of immune system, antiallergic effects, antifungal actions, preservation of food, and prevention of colon cancer. This review highlights the potential species of Lactic acid bacteria responsible for producing these effects. It has been concluded that lactic acid bacteria are highly beneficial microorganisms for human beings and are present abundantly in dairy products so their use should be promoted for good human health.

  15. Modeling the continuous lactic acid production process from wheat flour.

    PubMed

    Gonzalez, Karen; Tebbani, Sihem; Lopes, Filipa; Thorigné, Aurore; Givry, Sébastien; Dumur, Didier; Pareau, Dominique

    2016-01-01

    A kinetic model of the simultaneous saccharification, protein hydrolysis, and fermentation (SSPHF) process for lactic acid production from wheat flour has been developed. The model describes the bacterial growth, substrate consumption, lactic acid production, and maltose hydrolysis. The model was fitted and validated with data from SSPHF experiments obtained under different dilution rates. The results of the model are in good agreement with the experimental data. Steady state concentrations of biomass, lactic acid, glucose, and maltose as function of the dilution rate were predicted by the model. This steady state analysis is further useful to determine the operating conditions that maximize lactic acid productivity.

  16. Isolation of thermophilic L-lactic acid producing bacteria showing homo-fermentative manner under high aeration condition.

    PubMed

    Tongpim, Saowanit; Meidong, Ratchanu; Poudel, Pramod; Yoshino, Satoshi; Okugawa, Yuki; Tashiro, Yukihiro; Taniguchi, Masayuki; Sakai, Kenji

    2014-03-01

    By applying non-sterile open fermentation of food waste, various thermotolerant l-lactic acid-producing bacteria were isolated and identified. The predominant bacterial isolates showing higher accumulation of l-lactic acid belong to 3 groups of Bacillus coagulans, according to their 16S rRNA gene sequence similarities. B. coagulans strains M21 and M36 produced high amounts of l-lactic acid of high optical purity and lactic acid selectivity in model kitchen refuse medium and glucose-yeast extract-peptone medium. Other thermotolerant isolates resembling to Bacillus humi, B. ruris, B. subtilis, B. niacini and B. soli were also identified. These bacteria produced low amounts of l-lactic acid of more than 99% optical purity. All isolated strains showed the highest growth rate at temperatures around 55-60°C. They showed unique responses to various oxygen supply conditions. The majority of isolates produced l-lactic acid at a low overall oxygen transfer coefficient (KLa); however, acetic acid was produced instead of l-lactic acid at a high KLa. B. coagulans M21 was the only strain that produced high, consistent, and reproducible amounts of optically pure l-lactic acid (>99% optical purity) under high and low KLa conditions in a homo-fermentative manner.

  17. Acetic acid in aged vinegar affects molecular targets for thrombus disease management.

    PubMed

    Jing, Li; Yanyan, Zhang; Junfeng, Fan

    2015-08-01

    To elucidate the mechanism underlying the action of dietary vinegar on antithrombotic activity, acetic acid, the main acidic component of dietary vinegar, was used to determine antiplatelet and fibrinolytic activity. The results revealed that acetic acid significantly inhibits adenosine diphosphate (ADP)-, collagen-, thrombin-, and arachidonic acid (AA)-induced platelet aggregation. Acetic acid (2.00 mM) reduced AA-induced platelet aggregation to approximately 36.82 ± 1.31%, and vinegar (0.12 mL L(-1)) reduced the platelet aggregation induced by AA to 30.25 ± 1.34%. Further studies revealed that acetic acid exerts its effects by inhibiting cyclooxygenase-1 and the formation of thromboxane-A2. Organic acids including acetic acid, formic acid, lactic acid, citric acid, and malic acid also showed fibrinolytic activity; specifically, the fibrinolytic activity of acetic acid amounted to 1.866 IU urokinase per mL. Acetic acid exerted its fibrinolytic activity by activating plasminogen during fibrin crossing, thus leading to crosslinked fibrin degradation by the activated plasmin. These results suggest that organic acids in dietary vinegar play important roles in the prevention and cure of cardiovascular diseases.

  18. [Regulating acid stress resistance of lactic acid bacteria--a review].

    PubMed

    Wu, Chongde; Huang, Jun; Zhou, Rongqing

    2014-07-04

    As cell factories, lactic acid bacteria are widely used in food, agriculture, pharmaceutical and other industries. Acid stress is one the important survival challenges encountered by lactic acid bacteria both in fermentation process and in the gastrointestinal tract. Recently, the development of systems biology and metabolic engineering brings unprecedented opportunity for further elucidating the acid tolerance mechanisms and improving the acid stress resistance of lactic acid bacteria. This review addresses physiological mechanisms of lactic acid bacteria during acid stress. Moreover, strategies to improve the acid stress resistance of lactic acid were proposed.

  19. Microbial production of lactic acid: the latest development.

    PubMed

    Juturu, Veeresh; Wu, Jin Chuan

    2016-12-01

    Lactic acid is an important platform chemical for producing polylactic acid (PLA) and other value-added products. It is naturally produced by a wide spectrum of microbes including bacteria, yeast and filamentous fungi. In general, bacteria ferment C5 and C6 sugars to lactic acid by either homo- or hetero-fermentative mode. Xylose isomerase, phosphoketolase, transaldolase, l- and d-lactate dehydrogenases are the key enzymes that affect the ways of lactic acid production. Metabolic engineering of microbial strains are usually needed to produce lactic acid from unconventional carbon sources. Production of d-LA has attracted much attention due to the demand for producing thermostable PLA, but large scale production of d-LA has not yet been commercialized. Thermophilic Bacillus coagulans strains are able to produce l-lactic acid from lignocellulose sugars homo-fermentatively under non-sterilized conditions, but the lack of genetic tools for metabolically engineering them severely affects their development for industrial applications. Pre-treatment of agriculture biomass to obtain fermentable sugars is a pre-requisite for utilization of the huge amounts of agricultural biomass to produce lactic acid. The major challenge is to obtain quality sugars of high concentrations in a cost effective-way. To avoid or minimize the use of neutralizing agents during fermentation, genetically engineering the strains to make them resist acidic environment and produce lactic acid at low pH would be very helpful for reducing the production cost of lactic acid.

  20. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, P.V.; Coleman, R.D.

    1996-10-08

    A water and UV light degradable copolymer is described made from monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene glycol, propylene glycol, P-dioxanone, 1,5 dioxepan-2-one, 1,4-oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2 by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  1. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, Patrick V.; Coleman, Robert D.

    1996-01-01

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene glycol, propylene glycol, P-dioxanone, 1,5 dioxepan-2-one, 1,4-oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2 by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  2. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, Patrick V.; Coleman, Robert D.

    1994-01-01

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene and polyethylene glycols, propylene and polypropylene glycols, P-dioxanone, 1,5 dioxepan-2-one, 1,4 -oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2% by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  3. Water and UV degradable lactic acid polymers

    DOEpatents

    Bonsignore, P.V.; Coleman, R.D.

    1994-11-01

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer were selected from the class consisting of ethylene and polyethylene glycols, propylene and polypropylene glycols, P-dioxanone, 1,5 dioxepan-2-one, 1,4 -oxathialan-2-one, 1,4-dioxide and mixtures. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide where the high molecular weight polyethylene oxide is present in the range of from about 2% by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures to an agricultural site is also disclosed.

  4. Water and UV degradable lactic acid polymers

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.

    1990-06-26

    A water and UV light degradable copolymer of monomers of lactic acid and a modifying monomer selected from the class consisting of ethylene and polyethylane glycols (PVB 6/22/90), propylene and and polypropylene (PVB 6/22/90) glycols, P-dioxanone, 1, 5 dioxepan-2-one, 1,4 -oxathialan-2-one, 1,4-dioxide and mixtures thereof. These copolymers are useful for waste disposal and agricultural purposes. Also disclosed is a water degradable blend of polylactic acid or modified polylactic acid and high molecular weight polyethylene oxide wherein the high molecular weight polyethylene oxide is present in the range of from about 2% by weight to about 50% by weight, suitable for films. A method of applying an active material selected from the class of seeds, seedlings, pesticides, herbicides, fertilizers and mixtures thereof to an agricultural site is also disclosed.

  5. Vaginal pH and Microbicidal Lactic Acid When Lactobacilli Dominate the Microbiota

    PubMed Central

    O’Hanlon, Deirdre E.; Moench, Thomas R.; Cone, Richard A.

    2013-01-01

    Lactic acid at sufficiently acidic pH is a potent microbicide, and lactic acid produced by vaginal lactobacilli may help protect against reproductive tract infections. However, previous observations likely underestimated healthy vaginal acidity and total lactate concentration since they failed to exclude women without a lactobacillus-dominated vaginal microbiota, and also did not account for the high carbon dioxide, low oxygen environment of the vagina. Fifty-six women with low (0-3) Nugent scores (indicating a lactobacillus-dominated vaginal microbiota) and no symptoms of reproductive tract disease or infection, provided a total of 64 cervicovaginal fluid samples using a collection method that avoided the need for sample dilution and rigorously minimized aerobic exposure. The pH of samples was measured by microelectrode immediately after collection and under a physiological vaginal concentration of CO2. Commercial enzymatic assays of total lactate and total acetate concentrations were validated for use in CVF, and compared to the more usual HPLC method. The average pH of the CVF samples was 3.5 ± 0.3 (mean ± SD), range 2.8-4.2, and the average total lactate was 1.0% ± 0.2% w/v; this is a five-fold higher average hydrogen ion concentration (lower pH) and a fivefold higher total lactate concentration than in the prior literature. The microbicidal form of lactic acid (protonated lactic acid) was therefore eleven-fold more concentrated, and a markedly more potent microbicide, than indicated by prior research. This suggests that when lactobacilli dominate the vaginal microbiota, women have significantly more lactic acid-mediated protection against infections than currently believed. Our results invite further evaluations of the prophylactic and therapeutic actions of vaginal lactic acid, whether provided in situ by endogenous lactobacilli, by probiotic lactobacilli, or by products that reinforce vaginal lactic acid. PMID:24223212

  6. Vaginal pH and microbicidal lactic acid when lactobacilli dominate the microbiota.

    PubMed

    O'Hanlon, Deirdre E; Moench, Thomas R; Cone, Richard A

    2013-01-01

    Lactic acid at sufficiently acidic pH is a potent microbicide, and lactic acid produced by vaginal lactobacilli may help protect against reproductive tract infections. However, previous observations likely underestimated healthy vaginal acidity and total lactate concentration since they failed to exclude women without a lactobacillus-dominated vaginal microbiota, and also did not account for the high carbon dioxide, low oxygen environment of the vagina. Fifty-six women with low (0-3) Nugent scores (indicating a lactobacillus-dominated vaginal microbiota) and no symptoms of reproductive tract disease or infection, provided a total of 64 cervicovaginal fluid samples using a collection method that avoided the need for sample dilution and rigorously minimized aerobic exposure. The pH of samples was measured by microelectrode immediately after collection and under a physiological vaginal concentration of CO2. Commercial enzymatic assays of total lactate and total acetate concentrations were validated for use in CVF, and compared to the more usual HPLC method. The average pH of the CVF samples was 3.5 ± 0.3 (mean ± SD), range 2.8-4.2, and the average total lactate was 1.0% ± 0.2% w/v; this is a five-fold higher average hydrogen ion concentration (lower pH) and a fivefold higher total lactate concentration than in the prior literature. The microbicidal form of lactic acid (protonated lactic acid) was therefore eleven-fold more concentrated, and a markedly more potent microbicide, than indicated by prior research. This suggests that when lactobacilli dominate the vaginal microbiota, women have significantly more lactic acid-mediated protection against infections than currently believed. Our results invite further evaluations of the prophylactic and therapeutic actions of vaginal lactic acid, whether provided in situ by endogenous lactobacilli, by probiotic lactobacilli, or by products that reinforce vaginal lactic acid.

  7. Metabolic engineering as a tool for enhanced lactic acid production.

    PubMed

    Upadhyaya, Bikram P; DeVeaux, Linda C; Christopher, Lew P

    2014-12-01

    Metabolic engineering is a powerful biotechnological tool that finds, among others, increased use in constructing microbial strains for higher lactic acid productivity, lower costs and reduced pollution. Engineering the metabolic pathways has concentrated on improving the lactic acid fermentation parameters, enhancing the acid tolerance of production organisms and their abilities to utilize a broad range of substrates, including fermentable biomass-derived sugars. Recent efforts have focused on metabolic engineering of lactic acid bacteria as they produce high yields and have a small genome size that facilitates their genetic manipulation. We summarize here the current trends in metabolic engineering techniques and strategies for manipulating lactic acid producing organisms developed to address and overcome major challenges in the lactic acid production process.

  8. Towards lactic acid bacteria-based biorefineries.

    PubMed

    Mazzoli, Roberto; Bosco, Francesca; Mizrahi, Itzhak; Bayer, Edward A; Pessione, Enrica

    2014-11-15

    Lactic acid bacteria (LAB) have long been used in industrial applications mainly as starters for food fermentation or as biocontrol agents or as probiotics. However, LAB possess several characteristics that render them among the most promising candidates for use in future biorefineries in converting plant-derived biomass-either from dedicated crops or from municipal/industrial solid wastes-into biofuels and high value-added products. Lactic acid, their main fermentation product, is an attractive building block extensively used by the chemical industry, owing to the potential for production of polylactides as biodegradable and biocompatible plastic alternative to polymers derived from petrochemicals. LA is but one of many high-value compounds which can be produced by LAB fermentation, which also include biofuels such as ethanol and butanol, biodegradable plastic polymers, exopolysaccharides, antimicrobial agents, health-promoting substances and nutraceuticals. Furthermore, several LAB strains have ascertained probiotic properties, and their biomass can be considered a high-value product. The present contribution aims to provide an extensive overview of the main industrial applications of LAB and future perspectives concerning their utilization in biorefineries. Strategies will be described in detail for developing LAB strains with broader substrate metabolic capacity for fermentation of cheaper biomass.

  9. Acetic acid production from food wastes using yeast and acetic acid bacteria micro-aerobic fermentation.

    PubMed

    Li, Yang; He, Dongwei; Niu, Dongjie; Zhao, Youcai

    2015-05-01

    In this study, yeast and acetic acid bacteria strains were adopted to enhance the ethanol-type fermentation resulting to a volatile fatty acids yield of 30.22 g/L, and improve acetic acid production to 25.88 g/L, with food wastes as substrate. In contrast, only 12.81 g/L acetic acid can be obtained in the absence of strains. The parameters such as pH, oxidation reduction potential and volatile fatty acids were tested and the microbial diversity of different strains and activity of hydrolytic ferment were investigated to reveal the mechanism. The optimum pH and oxidation reduction potential for the acetic acid production were determined to be at 3.0-3.5 and -500 mV, respectively. Yeast can convert organic matters into ethanol, which is used by acetic acid bacteria to convert the organic wastes into acetic acid. The acetic acid thus obtained from food wastes micro-aerobic fermentation liquid could be extracted by distillation to get high-pure acetic acid.

  10. D-lactic acid production by metabolically engineered Saccharomyces cerevisiae.

    PubMed

    Ishida, Nobuhiro; Suzuki, Tomiko; Tokuhiro, Kenro; Nagamori, Eiji; Onishi, Toru; Saitoh, Satoshi; Kitamoto, Katsuhiko; Takahashi, Haruo

    2006-02-01

    Poly D-lactic acid is an important polymer because it improves the thermostability of poly L-lactic acid by the stereo complex formation. We constructed a metabolically engineered Saccharomyces cerevisiae that produces D-lactic acid efficiently. In this recombinant, the coding region of pyruvate decarboxylase 1 (PDC1) was completely deleted, and two copies of the D-lactate dehydrogenase (D-LDH) gene from Leuconostoc mesenteroides subsp. mesenteroides strain NBRC3426 were introduced into the genome. The D-lactate production reached 61.5 g/l, the amount of glucose being transformed into D-lactic acid being 61.2% under neutralizing conditions. Additionally, the yield of free D-lactic acid was also shown to be 53.0% under non-neutralizing conditions. It was confirmed that D-lactic acid of extremely high optical purity of 99.9% or higher. Our finding obtained the possibility of a new approach for pure d-lactic acid production without a neutralizing process compared with other techniques involving lactic acid bacteria and transgenic Escherichia coli.

  11. Microhydration of Neutral and Charged Acetic Acid.

    PubMed

    Krishnakumar, Parvathi; Maity, Dilip Kumar

    2017-01-19

    A systematic theoretical study has been carried out on the effect of sequential addition of water molecules to neutral and mono positively charged acetic acid molecules by applying first principle based electronic structure theory. Geometry, dipole moment, and polarizability of hydrated clusters of neutral and mono positively charged acetic acid of the type CH3COOH·nH2O (n = 1-8) and [CH3COOH·nH2O](+) (n = 1, 2) are calculated at the ωB97X-D/aug-cc-pVDZ level of theory. Free energies of formation of the hydrated acid clusters, at different temperatures and pressures are determined. Solvent stabilization energy and interaction energy are also calculated at the CCSD(T)/6-311++G(d,p) level of theory. It is observed that in the case of neutral acetic acid, proton transfer from the acid molecule to solvent water molecules does not occur even with eight water molecules and the acid molecule remains in the undissociated form. High-energy equilibrium structures showing dissociation of acetic acid are obtained in case of hexahydrated and larger hydrated clusters only. However, dissociation of mono positively charged acetic acid occurs with just two water molecules. Interestingly, it is noted that in the case of dissociation, calculated bond dipole moments of the dissociating bonds of acetic acid in microhydated clusters shows a characteristic feature. IR spectra of CH3COOH·nH2O (n = 1-8) and [CH3COOH·nH2O](+) (n = 1-3) clusters are simulated and compared with the available experimental data.

  12. Dynamic Protonation Equilibrium of Solvated Acetic Acid

    SciTech Connect

    Gu, Wei; Frigato, Tomaso; Straatsma, TP; Helms, Volkhard H.

    2007-04-13

    For the first time, the dynamic protonation equilibrium between an amino acid side chain analogue and bulk water as well as the diffusion properties of the excess proton were successfully reproduced through unbiased computer simulations. During a 50 ns Q-HOP MD simulation, two different regimes of proton transfer were observed. Extended phases of frequent proton swapping between acetic acid and nearby water were separated by phases where the proton freely diffuses in the simulation box until it is captured again by acetic acid. The pKa of acetic acid was calculated around 3.0 based on the relative population of protonated and deprotonated states and the diffusion coefficient of excess proton was computed from the average mean squared displacement in the simulation. Both calculated values agree well with the experimental measurements.

  13. Acetic acid bacteria spoilage of bottled red wine -- a review.

    PubMed

    Bartowsky, Eveline J; Henschke, Paul A

    2008-06-30

    Acetic acid bacteria (AAB) are ubiquitous organisms that are well adapted to sugar and ethanol rich environments. This family of Gram-positive bacteria are well known for their ability to produce acetic acid, the main constituent in vinegar. The oxidation of ethanol through acetaldehyde to acetic acid is well understood and characterised. AAB form part of the complex natural microbial flora of grapes and wine, however their presence is less desirable than the lactic acid bacteria and yeast. Even though AAB were described by Pasteur in the 1850s, wine associated AAB are still difficult to cultivate on artificial laboratory media and until more recently, their taxonomy has not been well characterised. Wine is at most risk of spoilage during production and the presence of these strictly aerobic bacteria in grape must and during wine maturation can be controlled by eliminating, or at least limiting oxygen, an essential growth factor. However, a new risk, spoilage of wine by AAB after packaging, has only recently been reported. As wine is not always sterile filtered prior to bottling, especially red wine, it often has a small resident bacterial population (<10(3) cfu/mL), which under conducive conditions might proliferate. Bottled red wines, sealed with natural cork closures, and stored in a vertical upright position may develop spoilage by acetic acid bacteria. This spoilage is evident as a distinct deposit of bacterial biofilm in the neck of the bottle at the interface of the wine and the headspace of air, and is accompanied with vinegar, sherry, bruised apple, nutty, and solvent like off-aromas, depending on the degree of spoilage. This review focuses on the wine associated AAB species, the aroma and flavour changes in wine due to AAB metabolism, discusses the importance of oxygen ingress into the bottle and presents a hypothesis for the mechanism of spoilage of bottled red wine.

  14. Glycerol metabolism and bitterness producing lactic acid bacteria in cidermaking.

    PubMed

    Garai-Ibabe, G; Ibarburu, I; Berregi, I; Claisse, O; Lonvaud-Funel, A; Irastorza, A; Dueñas, M T

    2008-02-10

    Several lactic acid bacteria were isolated from bitter tasting ciders in which glycerol was partially removed. The degradation of glycerol via glycerol dehydratase pathway was found in 22 out of 67 isolates. The confirmation of glycerol degradation by this pathway was twofold: showing their glycerol dehydratase activity and detecting the presence of the corresponding gene by a PCR method. 1,3-propanediol (1,3-PDL) and 3-hydroxypropionic acid (3-HP) were the metabolic end-products of glycerol utilization, and the accumulation of the acrolein precursor 3-hydroxypropionaldehyde (3-HPA) was also detected in most of them. The strain identification by PCR-DGGE rpoB showed that Lactobacillus collinoides was the predominant species and only 2 belonged to Lactobacillus diolivorans. Environmental conditions conducting to 3-HPA accumulation in cidermaking were studied by varying the fructose concentration, pH and incubation temperature in L. collinoides 17. This strain failed to grow with glycerol as sole carbon source and the addition of fructose enhanced both growth and glycerol degradation. Regarding end-products of glycerol metabolism, 1,3-PDL was always the main end-product in all environmental conditions assayed, the only exception being the culture with 5.55 mM fructose, where equimolar amounts of 1,3-PDL and 3-HP were found. The 3-HPA was transitorily accumulated in the culture medium under almost all culture conditions, the degradation rate being notably slower at 15 degrees C. However, no disappearance of 3-HPA was found at pH 3.6, a usual value in cider making. After sugar exhaustion, L. collinoides 17 oxidated lactic acid and/or mannitol to obtain energy and these oxidations were accompanied by the removal of the toxic 3-HPA increasing the 1,3-PDL, 3-HP and acetic acid contents.

  15. Production of lactic acid from pulp mill solid waste and xylose using Lactobacillus delbrueckii (NRRL B445).

    PubMed

    Thomas, S

    2000-01-01

    Using the simultaneous saccharification and fermentation (SSF) technique, pulp mill solid waste cellulose was converted into glucose using cellulase enzyme and glucose into lactic acid using NRRL B445. SSF experiments were conducted at various pH levels, temperatures, and nutrient concentrations, and the lactic acid yield ranged from 86 to 97%. The depletion of xylose in SSF was further investigated by inoculating NRRL B445 into a xylose-only medium. On prolonged incubation, depletion of xylose with lactic acid production was observed. An experimental procedure with a nonglucose medium was developed to eliminate the lag phase. From xylose fermentation, Lactobacillus delbrueckii yielded 88-92% lactic acid and 2-12% acetic acid.

  16. Lactic acid production in Saccharomyces cerevisiae is modulated by expression of the monocarboxylate transporters Jen1 and Ady2.

    PubMed

    Pacheco, António; Talaia, Gabriel; Sá-Pessoa, Joana; Bessa, Daniela; Gonçalves, Maria José; Moreira, Roxana; Paiva, Sandra; Casal, Margarida; Queirós, Odília

    2012-05-01

    We aimed to manipulate the metabolism of Saccharomyces cerevisiae to produce lactic acid and search for the potential influence of acid transport across the plasma membrane in this process. Saccharomyces cerevisiae W303-1A is able to use l-lactic acid but its production in our laboratory has not previously been detected. When the l-LDH gene from Lactobacillus casei was expressed in S. cerevisiae W303-1A and in the isogenic mutants jen1∆, ady2∆ and jen1∆ ady2∆, all strains were able to produce lactic acid, but higher titres were achieved in the mutant strains. In strains constitutively expressing both LDH and JEN1 or ADY2, a higher external lactic acid concentration was found when glucose was present in the medium, but when glucose was exhausted, its consumption was more pronounced. These results demonstrate that expression of monocarboxylate permeases influences lactic acid production. Ady2 has been previously characterized as an acetate permease but our results demonstrated its additional role in lactate uptake. Overall, we demonstrate that monocarboxylate transporters Jen1 and Ady2 are modulators of lactic acid production and may well be used to manipulate lactic acid export in yeast cells.

  17. Progress in lactic acid bacterial phage research

    PubMed Central

    2014-01-01

    Research on lactic acid bacteria (LAB) has advanced significantly over the past number of decades and these developments have been driven by the parallel advances in technologies such as genomics, bioinformatics, protein expression systems and structural biology, combined with the ever increasing commercial relevance of this group of microorganisms. Some of the more significant and impressive outputs have been in the domain of bacteriophage-host interactions which provides a prime example of the cutting-edge model systems represented by LAB research. Here, we present a retrospective overview of the key advances in LAB phage research including phage-host interactions and co-evolution. We describe how in many instances this knowledge can be pivotal in creating real improvements in the application of LAB cultures in commercial practice. PMID:25185514

  18. Biotechnological production of enantiomerically pure d-lactic acid.

    PubMed

    Klotz, Silvia; Kaufmann, Norman; Kuenz, Anja; Prüße, Ulf

    2016-11-01

    The fermentation process of l-lactic acid is well known. Little importance was attached to d-lactic acid, but in the past 10 years, d-lactic acid gained significantly in importance. d-Lactic acid is an interesting precursor for manufacturing heat-resistant polylactic acid (PLA) bioplastics which can be widely used, for example as packaging material, coatings, for textiles or in the automotive industry.This review provides a comprehensive overview of the most recent developments, including a spectrum of studied microorganisms and their capabilities for the production of d-lactic acid. Additionally, the technological achievements in biotechnological d-lactic acid production including fermentation techniques like fed batch, simultaneous saccharification, and fermentation and continuous techniques are presented. Attention is also turned to suitable alternative substrates and their applicability in fermentation processes. Furthermore, advantages and disadvantages of product recovery and purification are discussed. Economic aspects of PLA are pointed out, and the present industrial producers of lactic acid are briefly introduced.

  19. Progress in engineering acid stress resistance of lactic acid bacteria.

    PubMed

    Wu, Chongde; Huang, Jun; Zhou, Rongqing

    2014-02-01

    Lactic acid bacteria (LAB) are widely used for the production of a variety of fermented foods, and are considered as probiotic due to their health-promoting effect. However, LAB encounter various environmental stresses both in industrial fermentation and application, among which acid stress is one of the most important survival challenges. Improving the acid stress resistance may contribute to the application and function of probiotic action to the host. Recently, the advent of genomics, functional genomics and high-throughput technologies have allowed for the understanding of acid tolerance mechanisms at a systems level, and many method to improve acid tolerance have been developed. This review describes the current progress in engineering acid stress resistance of LAB. Special emphasis is placed on engineering cellular microenvironment (engineering amino acid metabolism, introduction of exogenous biosynthetic capacity, and overproduction of stress response proteins) and maintaining cell membrane functionality. Moreover, strategies to improve acid tolerance and the related physiological mechanisms are also discussed.

  20. L-Lactic Acid Production by Lactobacillus rhamnosus ATCC 10863

    PubMed Central

    Senedese, Ana Lívia Chemeli; Maciel Filho, Rubens; Maciel, Maria Regina Wolf

    2015-01-01

    Lactic acid has been shown to have the most promising application in biomaterials as poly(lactic acid). L. rhamnosus ATCC 10863 that produces L-lactic acid was used to perform the fermentation and molasses was used as substrate. A solution containing 27.6 g/L of sucrose (main composition of molasses) and 3.0 g/L of yeast extract was prepared, considering the final volume of 3,571 mL (14.0% (v/v) inoculum). Batch and fed batch fermentations were performed with temperature of 43.4°C and pH of 5.0. At the fed batch, three molasses feed were applied at 12, 24, and 36 hours. Samples were taken every two hours and the amounts of lactic acid, sucrose, glucose, and fructose were determined by HPLC. The sucrose was barely consumed at both processes; otherwise the glucose and fructose were almost entirely consumed. 16.5 g/L of lactic acid was produced at batch and 22.0 g/L at fed batch. Considering that lactic acid was produced due to the low concentration of the well consumed sugars, the final amount was considerable. The cell growth was checked and no substrate inhibition was observed. A sucrose molasses hydrolysis is suggested to better avail the molasses fermentation with this strain, surely increasing the L-lactic acid. PMID:25922852

  1. Direct fermentation of potato starch and potato residues to lactic acid by Geobacillus stearothermophilus under non-sterile conditions

    PubMed Central

    Smerilli, Marina; Neureiter, Markus; Wurz, Stefan; Haas, Cornelia; Frühauf, Sabine; Fuchs, Werner

    2015-01-01

    BACKGROUND Lactic acid is an important biorefinery platform chemical. The use of thermophilic amylolytic microorganisms to produce lactic acid by fermentation constitutes an efficient strategy to reduce operating costs, including raw materials and sterilization costs. RESULTS A process for the thermophilic production of lactic acid by Geobacillus stearothermophilus directly from potato starch was characterized and optimized. Geobacillus stearothermophilus DSM 494 was selected out of 12 strains screened for amylolytic activity and the ability to form lactic acid as the major product of the anaerobic metabolism. In total more than 30 batches at 3–l scale were run at 60 °C under non-sterile conditions. The process developed produced 37 g L−1 optically pure (98%) L-lactic acid in 20 h from 50 g L−1 raw potato starch. As co-metabolites smaller amounts (<7% w/v) of acetate, formate and ethanol were formed. Yields of lactic acid increased from 66% to 81% when potato residues from food processing were used as a starchy substrate in place of raw potato starch. CONCLUSIONS Potato starch and residues were successfully converted to lactic acid by G. stearothermophilus. The process described in this study provides major benefits in industrial applications and for the valorization of starch-rich waste streams. © 2015 The Authors.Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:25937690

  2. Acetal phosphatidic acids: novel platelet aggregating agents.

    PubMed

    Brammer, J P; Maguire, M H; Walaszek, E J; Wiley, R A

    1983-05-01

    1 Palmitaldehyde, olealdehyde and linolealdehyde acetal phosphatidic acids induced rapid shape change and dose-dependent biphasic aggregation of human platelets in platelet-rich plasma; aggregation was reversible at low doses and irreversible at high doses of the acetal phosphatidic acids. The palmitaldehyde congener elicited monophasic dose-dependent aggregation of sheep platelets in platelet-rich plasma.2 The threshold concentration for palmitaldehyde acetal phosphatidic acid (PGAP)-induced platelet aggregation was 2.5-5 muM for human platelets and 0.25-0.5 muM for sheep platelets. PGAP was 4-5 times as potent versus human platelets as the olealdehyde and linolealdehyde acetal phosphatidic acids, which were equipotent.3 PGAP-induced irreversible aggregation of [(14)C]-5-hydroxytryptamine ([(14)C]-5-HT)-labelled human platelets in platelet-rich plasma was accompanied by release of 44.0+/-2.4% (s.e.) of the platelet [(14)C]-5-HT; reversible aggregation was not associated with release. In contrast, PGAP-induced release of [(14)C]-5-HT-labelled sheep platelets was dose-dependent.4 The adenosine diphosphate (ADP) antagonist, 2-methylthio-AMP, and the cyclo-oxygenase inhibitor, aspirin, abolished PGAP-induced second phase aggregation and release in human platelets but did not affect the first, reversible, phase of aggregation. Both the first and second phases of PGAP-induced aggregation were abolished by chlorpromazine, by the phospholipase A(2) inhibitor, mepacrine, and by nmolar concentrations of prostaglandin E(1) (PGE(1)); these agents abolished the second, but not the first phase of ADP-induced aggregation.5 The related phospholipids, lecithin, lysolecithin and phosphatidic acid, at <100 muM, neither induced aggregation of human platelets in platelet-rich plasma, nor modified PGAP-induced aggregation; 1-palmityl lysophosphatidic acid elicited aggregation of human platelets at a threshold concentration of 100 muM.6 It is concluded that the acetal phosphatidic acids

  3. Use of autochthonous lactic acid bacteria starters to ferment mango juice for promoting its probiotic roles.

    PubMed

    Liao, Xue-Yi; Guo, Li-Qiong; Ye, Zhi-Wei; Qiu, Ling-Yan; Gu, Feng-Wei; Lin, Jun-Fang

    2016-05-18

    Strains of Leuconostoc mesenteroides, Pediococcus pentosaceus, and Lactobacillus brevis were identified from mango fruits by partial 16S rDNA gene sequence. Based on the ability of producing mannitol and diacetyl, Leuconostoc mesenteroides MPL18 and MPL39 were selected within the lactic acid bacteria isolates, and used as mixed starters to ferment mango juice (MJ). Both the autochthonous strains grew well in fermented mango juice (FMJ) and remained viable at 9.81 log cfu mL(-1) during 30 days of storage at 4°C. The content of total sugar of FMJ was lower than that of MJ, while the concentration of mannitol was higher than that of MJ, and the concentration of diacetyl was 3.29 ± 0.12 mg L(-1). Among detected organic acids including citric acid, gallic acid, lactic acid, and acetic acid, only citric acid and gallic acid were found in MJ, while all detected organic acids were found in FMJ. The concentration of lactic acid of FMJ was the highest (78.62 ± 13.66 mM) among all detected organic acids. The DPPH radical scavenging capacity of FMJ was higher than that of MJ. Total phenolic compounds were better preserved in FMJ. The acidity and sweetness had a noticeable impact on the overall acceptance of the treated sample.

  4. Lactic acid bacteria production from whey.

    PubMed

    Mondragón-Parada, María Elena; Nájera-Martínez, Minerva; Juárez-Ramírez, Cleotilde; Galíndez-Mayer, Juvencio; Ruiz-Ordaz, Nora; Cristiani-Urbina, Eliseo

    2006-09-01

    The main purpose of this work was to isolate and characterize lactic acid bacteria (LAB) strains to be used for biomass production using a whey-based medium supplemented with an ammonium salt and with very low levels of yeast extract (0.25 g/L). Five strains of LAB were isolated from naturally soured milk after enrichment in whey-based medium. One bacterial isolate, designated MNM2, exhibited a remarkable capability to utilize whey lactose and give a high biomass yield on lactose. This strain was identified as Lactobacillus casei by its 16S rDNA sequence. A kinetic study of cell growth, lactose consumption, and titratable acidity production of this bacterial strain was performed in a bioreactor. The biomass yield on lactose, the percentage of lactose consumption, and the maximum increase in cell mass obtained in the bioreactor were 0.165 g of biomass/g of lactose, 100%, and 2.0 g/L, respectively, which were 1.44, 1.11, and 2.35 times higher than those found in flask cultures. The results suggest that it is possible to produce LAB biomass from a whey-based medium supplemented with minimal amounts of yeast extract.

  5. Efficient non-sterilized fermentation of biomass-derived xylose to lactic acid by a thermotolerant Bacillus coagulans NL01.

    PubMed

    Ouyang, Jia; Cai, Cong; Chen, Hai; Jiang, Ting; Zheng, Zhaojuan

    2012-12-01

    Xylose is the major pentose and the second most abundant sugar in lignocellulosic feedstock. Its efficient utilization is regarded as a technical barrier to the commercial production of bulk chemicals from lignocellulosic biomass. This work aimed at evaluating the lactic acid production from the biomass-derived xylose using non-sterilized fermentation by Bacillus coagulans NL01. A maximum lactic acid concentration of about 75 g/L was achieved from xylose of 100 g/L after 72 h batch fermentation. Acetic acid and levulinic acid were identified as important inhibitors in xylose fermentation, which markedly reduced lactic acid productivity at 15 and 1.0 g/L, respectively. But low concentrations of formic acid (<2 g/L) exerted a stimulating effect on the lactic acid production. When prehydrolysate containing total 25.45 g/L monosaccharide was fermented with B. coagulans NL01, the same preference for glucose, xylose, and arabinose was observed and18.2 g/L lactic acid was obtained after 48 h fermentation. These results proved that B. coagulans NL01 was potentially well-suited for producing lactic acid from underutilized xylose-rich prehydrolysates.

  6. Impact of Lactic Acid and Hydrogen Ion on the Simultaneous Fermentation of Glucose and Xylose by the Carbon Catabolite Derepressed Lactobacillus brevis ATCC 14869.

    PubMed

    Jeong, Kyung Hun; Israr, Beenish; Shoemaker, Sharon P; Mills, David A; Kim, Jaehan

    2016-07-28

    Lactobacillus brevis ATCC 14869 exhibited a carbon catabolite de-repressed (CCR) phenotype which has ability to consume fermentable sugar simultaneously with glucose. To evaluate this unusual phenotype under harsh conditions during fermentation, the effect of lactic acid and hydrogen ion concentrations on L. brevis ATCC 14869 were examined. Kinetic equations describing the relationship between specific cell growth rate and lactic acid or hydrogen ion concentration has been reduced. The change of substrate utilization and product formation according to lactic acid and hydrogen ion concentration in the media were quantitatively described. Moreover; utilization of other compounds were also observed along with hydrogen ion and lactic acid concentration simultaneously. It has been found that substrate preference changes significantly regarding to utilization of compounds in media. That could result into formation of two-carbon products. In particular, acetic acid present in the media as sodium acetate were consumed by L. brevis ATCC 14869 under extreme pH of both acid and alkaline conditions.

  7. Hydroxycinnamic Acids Used as External Acceptors of Electrons: an Energetic Advantage for Strictly Heterofermentative Lactic Acid Bacteria

    PubMed Central

    Filannino, Pasquale; Gobbetti, Marco; De Angelis, Maria

    2014-01-01

    The metabolism of hydroxycinnamic acids by strictly heterofermentative lactic acid bacteria (19 strains) was investigated as a potential alternative energy route. Lactobacillus curvatus PE5 was the most tolerant to hydroxycinnamic acids, followed by strains of Weissella spp., Lactobacillus brevis, Lactobacillus fermentum, and Leuconostoc mesenteroides, for which the MIC values were the same. The highest sensitivity was found for Lactobacillus rossiae strains. During growth in MRS broth, lactic acid bacteria reduced caffeic, p-coumaric, and ferulic acids into dihydrocaffeic, phloretic, and dihydroferulic acids, respectively, or decarboxylated hydroxycinnamic acids into the corresponding vinyl derivatives and then reduced the latter compounds to ethyl compounds. Reductase activities mainly emerged, and the activities of selected strains were further investigated in chemically defined basal medium (CDM) under anaerobic conditions. The end products of carbon metabolism were quantified, as were the levels of intracellular ATP and the NAD+/NADH ratio. Electron and carbon balances and theoretical ATP/glucose yields were also estimated. When CDM was supplemented with hydroxycinnamic acids, the synthesis of ethanol decreased and the concentration of acetic acid increased. The levels of these metabolites reflected on the alcohol dehydrogenase and acetate kinase activities. Overall, some biochemical traits distinguished the common metabolism of strictly heterofermentative strains: main reductase activity toward hydroxycinnamic acids, a shift from alcohol dehydrogenase to acetate kinase activities, an increase in the NAD+/NADH ratio, and the accumulation of supplementary intracellular ATP. Taken together, the above-described metabolic responses suggest that strictly heterofermentative lactic acid bacteria mainly use hydroxycinnamic acids as external acceptors of electrons. PMID:25261518

  8. Hydroxycinnamic acids used as external acceptors of electrons: an energetic advantage for strictly heterofermentative lactic acid bacteria.

    PubMed

    Filannino, Pasquale; Gobbetti, Marco; De Angelis, Maria; Di Cagno, Raffaella

    2014-12-01

    The metabolism of hydroxycinnamic acids by strictly heterofermentative lactic acid bacteria (19 strains) was investigated as a potential alternative energy route. Lactobacillus curvatus PE5 was the most tolerant to hydroxycinnamic acids, followed by strains of Weissella spp., Lactobacillus brevis, Lactobacillus fermentum, and Leuconostoc mesenteroides, for which the MIC values were the same. The highest sensitivity was found for Lactobacillus rossiae strains. During growth in MRS broth, lactic acid bacteria reduced caffeic, p-coumaric, and ferulic acids into dihydrocaffeic, phloretic, and dihydroferulic acids, respectively, or decarboxylated hydroxycinnamic acids into the corresponding vinyl derivatives and then reduced the latter compounds to ethyl compounds. Reductase activities mainly emerged, and the activities of selected strains were further investigated in chemically defined basal medium (CDM) under anaerobic conditions. The end products of carbon metabolism were quantified, as were the levels of intracellular ATP and the NAD(+)/NADH ratio. Electron and carbon balances and theoretical ATP/glucose yields were also estimated. When CDM was supplemented with hydroxycinnamic acids, the synthesis of ethanol decreased and the concentration of acetic acid increased. The levels of these metabolites reflected on the alcohol dehydrogenase and acetate kinase activities. Overall, some biochemical traits distinguished the common metabolism of strictly heterofermentative strains: main reductase activity toward hydroxycinnamic acids, a shift from alcohol dehydrogenase to acetate kinase activities, an increase in the NAD(+)/NADH ratio, and the accumulation of supplementary intracellular ATP. Taken together, the above-described metabolic responses suggest that strictly heterofermentative lactic acid bacteria mainly use hydroxycinnamic acids as external acceptors of electrons.

  9. Heart Rate Response and Lactic Acid Concentration in Squash Players.

    ERIC Educational Resources Information Center

    Beaudin, Paula; And Others

    1978-01-01

    It was concluded that playing squash is an activity that results in heart rate responses of sufficient intensity to elicit aerobic training effects without producing high lactic acid concentration in the blood. (MM)

  10. Fermentation and recovery process for lactic acid production

    DOEpatents

    Tsai, S.P.; Moon, S.H.; Coleman, R.

    1995-11-07

    A method is described for converting starch to glucose and fermenting glucose to lactic acid, including simultaneous saccharification and fermentation through use of a novel consortium of bacterial strains. 2 figs.

  11. Materials and methods for efficient lactic acid production

    DOEpatents

    Zhou, Shengde; Ingram, Lonnie O'Neal; Shanmugam, Keelnatham T.; Yomano, Lorraine; Grabar, Tammy B.; Moore, Jonathan C.

    2009-12-08

    The present invention provides derivatives of ethanologenic Escherichia coli K011 constructed for the production of lactic acid. The transformed E. coli of the invention are prepared by deleting the genes that encode competing pathways followed by a growth-based selection for mutants with improved performance. These transformed E. coli are useful for providing an increased supply of lactic acid for use in food and industrial applications.

  12. The Role of Lactic Acid Adsorption by Ion Exchange Chromatography

    PubMed Central

    Zhang, Tongcun; Zhang, Jian; Jia, Shiru; Yu, Changyan; Jiang, Kunyu; Gao, Nianfa

    2010-01-01

    Background The polyacrylic resin Amberlite IRA-67 is a promising adsorbent for lactic acid extraction from aqueous solution, but little systematic research has been devoted to the separation efficiency of lactic acid under different operating conditions. Methodology/Principal Findings In this paper, we investigated the effects of temperature, resin dose and lactic acid loading concentration on the adsorption of lactic acid by Amberlite IRA-67 in batch kinetic experiments. The obtained kinetic data followed the pseudo-second order model well and both the equilibrium and ultimate adsorption slightly decreased with the increase of the temperature at 293–323K and 42.5 g/liter lactic acid loading concentration. The adsorption was a chemically heterogeneous process with a mean free energy value of 12.18 kJ/mol. According to the Boyd_plot, the lactic acid uptake process was primarily found to be an intraparticle diffusion at a lower concentration (<50 g/liter) but a film diffusion at a higher concentration (>70 g/liter). The values of effective diffusion coefficient Di increased with temperature. By using our Equation (21), the negative values of ΔG° and ΔH° revealed that the adsorption process was spontaneous and exothermic. Moreover, the negative value of ΔS° reflected the decrease of solid-liquid interface randomness at the solid-liquid interface when adsorbing lactic acid on IRA-67. Conclusions/Significance With the weakly basic resin IRA-67, in situ product removal of lactic acid can be accomplished especially from an open and thermophilic fermentation system without sterilization. PMID:21085600

  13. Materials and methods for efficient lactic acid production

    SciTech Connect

    Zhou, Shengde; Ingram, Lonnie O'Neal; Shanmugam, Keelnatham T; Yomano, Lorraine; Grabar, Tammy B; Moore, Jonathan C

    2013-04-23

    The present invention provides derivatives of Escherichia coli constructed for the production of lactic acid. The transformed E. coli of the invention are prepared by deleting the genes that encode competing pathways followed by a growth-based selection for mutants with improved performance. These transformed E. coli are useful for providing an increased supply of lactic acid for use in food and industrial applications.

  14. Metabolism of lactic acid in fermented cucumbers by Lactobacillus buchneri and related species, potential spoilage organisms in reduced salt fermentations.

    PubMed

    Johanningsmeier, Suzanne D; McFeeters, Roger F

    2013-09-01

    Recent evidence suggests that Lactobacillus buchneri may play an important role in spoilage-associated secondary fermentation of cucumbers. Lactic acid degradation during fermented cucumber spoilage is influenced by sodium chloride (NaCl) concentration, pH, and presence of oxygen. Objectives were to evaluate these factors on lactic acid utilization by L. buchneri, and to compare the biochemical changes to those which occur during fermented cucumber spoilage. Effects of NaCl (0, 2, 4, and 6% w/w), pH (3.8 vs 5.0), and aerobic environment were investigated using fermented cucumber media (FC) inoculated with spoilage microorganisms. At pH 3.8, L. buchneri degraded lactic acid in all NaCl concentrations. The highest rate of lactic acid utilization occurred in FC with 2% NaCl (P < 0.05). Lactic acid utilization was nearly identical under aerobic and anaerobic conditions, indicating that oxygen does not influence lactate metabolism by L. buchneri. Lactic acid utilization was accompanied by increases in acetic acid and 1,2-propanediol, and Lactobacillus rapi was able to convert 1,2-propanediol to propionic acid and propanol. L. buchneri initiated spoilage in a wide range of environmental conditions that may be present in commercial cucumber fermentations, and L. rapi may act syntrophically with L. buchneri to produce the commonly observed spoilage metabolites.

  15. Food phenolics and lactic acid bacteria.

    PubMed

    Rodríguez, Héctor; Curiel, José Antonio; Landete, José María; de las Rivas, Blanca; López de Felipe, Félix; Gómez-Cordovés, Carmen; Mancheño, José Miguel; Muñoz, Rosario

    2009-06-30

    Phenolic compounds are important constituents of food products of plant origin. These compounds are directly related to sensory characteristics of foods such as flavour, astringency, and colour. In addition, the presence of phenolic compounds on the diet is beneficial to health due to their chemopreventive activities against carcinogenesis and mutagenesis, mainly due to their antioxidant activities. Lactic acid bacteria (LAB) are autochthonous microbiota of raw vegetables. To get desirable properties on fermented plant-derived food products, LAB has to be adapted to the characteristics of the plant raw materials where phenolic compounds are abundant. Lactobacillus plantarum is the commercial starter most frequently used in the fermentation of food products of plant origin. However, scarce information is still available on the influence of phenolic compounds on the growth and viability of L. plantarum and other LAB species. Moreover, metabolic pathways of biosynthesis or degradation of phenolic compounds in LAB have not been completely described. Results obtained in L. plantarum showed that L. plantarum was able to degrade some food phenolic compounds giving compounds influencing food aroma as well as compounds presenting increased antioxidant activity. Recently, several L. plantarum proteins involved in the metabolism of phenolic compounds have been genetically and biochemically characterized. The aim of this review is to give a complete and updated overview of the current knowledge among LAB and food phenolics interaction, which could facilitate the possible application of selected bacteria or their enzymes in the elaboration of food products with improved characteristics.

  16. Overview on mechanisms of acetic acid resistance in acetic acid bacteria.

    PubMed

    Wang, Bin; Shao, Yanchun; Chen, Fusheng

    2015-02-01

    Acetic acid bacteria (AAB) are a group of gram-negative or gram-variable bacteria which possess an obligate aerobic property with oxygen as the terminal electron acceptor, meanwhile transform ethanol and sugar to corresponding aldehydes, ketones and organic acids. Since the first genus Acetobacter of AAB was established in 1898, 16 AAB genera have been recorded so far. As the main producer of a world-wide condiment, vinegar, AAB have evolved an elegant adaptive system that enables them to survive and produce a high concentration of acetic acid. Some researches and reviews focused on mechanisms of acid resistance in enteric bacteria and made the mechanisms thoroughly understood, while a few investigations did in AAB. As the related technologies with proteome, transcriptome and genome were rapidly developed and applied to AAB research, some plausible mechanisms conferring acetic acid resistance in some AAB strains have been published. In this review, the related mechanisms of AAB against acetic acid with acetic acid assimilation, transportation systems, cell morphology and membrane compositions, adaptation response, and fermentation conditions will be described. Finally, a framework for future research for anti-acid AAB will be provided.

  17. Poly(lactic acid) and poly(lactic-co-glycolic acid) particles as versatile carrier platforms for vaccine delivery.

    PubMed

    Pavot, Vincent; Berthet, Morgane; Rességuier, Julien; Legaz, Sophie; Handké, Nadège; Gilbert, Sarah C; Paul, Stéphane; Verrier, Bernard

    2014-12-01

    The development of safe and effective vaccines for cancer and infectious diseases remains a major goal in public health. Over the last two decades, controlled release of vaccine antigens and immunostimulant molecules has been achieved using nanometer or micron-sized delivery vehicles synthesized using biodegradable polymers. In addition to achieving a depot effect, enhanced vaccine efficacy using such delivery vehicles has been attributed to efficient targeting of antigen presenting cells such as dendritic cells. Biodegradable and biocompatible poly(lactic acid) and poly(lactic-co-glycolic acid) polymers belong to one such family of polymers that have been a popular choice of material used in the design of these delivery vehicles. This review summarizes research findings from ourselves and others highlighting the promise of poly(lactic acid)- and poly(lactic-co-glycolic acid)-based vaccine carriers in enhancing immune responses.

  18. Analysis of microbial community variation during the mixed culture fermentation of agricultural peel wastes to produce lactic acid.

    PubMed

    Liang, Shaobo; Gliniewicz, Karol; Gerritsen, Alida T; McDonald, Armando G

    2016-05-01

    Mixed cultures fermentation can be used to convert organic wastes into various chemicals and fuels. This study examined the fermentation performance of four batch reactors fed with different agricultural (orange, banana, and potato (mechanical and steam)) peel wastes using mixed cultures, and monitored the interval variation of reactor microbial communities with 16S rRNA genes using Illumina sequencing. All four reactors produced similar chemical profile with lactic acid (LA) as dominant compound. Acetic acid and ethanol were also observed with small fractions. The Illumina sequencing results revealed the diversity of microbial community decreased during fermentation and a community of largely lactic acid producing bacteria dominated by species of Lactobacillus developed.

  19. Production of Optically Pure D-Lactic Acid by the Combined use of Weissella sp. S26 and Bacillus sp. ADS3.

    PubMed

    Li, Qingxin; Hudari, Mohammad Sufian Bin; Wu, Jin Chuan

    2016-01-01

    Optically pure D-lactic acid was produced from glucose, xylose, or starch by the combined use of Weissella sp. S26 and Bacillus sp. ADS3, two native bacterial strains isolated from Singapore environment. Weissella sp. S26 was used to ferment various sugars to lactic acid rich in D-isomer followed by sterilization of the broth and inoculation of Bacillus sp. ADS3 cells to selectively degrade acetic acid (if any) and L-lactic acid. In a simultaneous saccharification and fermentation of starch by Weissella sp. S26 in 1 L of modified MRS medium containing 50 g/L starch at 30 °C, lactic acid reached 24.2 g/L (23.6 g/L of D-isomers and 0.6 g/L of L-isomers), and acetic acid was 11.8 g/L at 37 h. The fermentation broth was sterilized at 100 °C for 20 min and cooled down to 30 °C followed by inoculation of Bacillus sp. ADS3 (10 %, v/v), and the mixture was kept at 30 °C for 115 h. Acetic acid was completely removed, and L-lactic acid was largely removed giving an optical purity of D-lactic acid as high as 99.5 %.

  20. Rotational study of the bimolecule acetic acid-fluoroacetic acid

    NASA Astrophysics Data System (ADS)

    Feng, Gang; Gou, Qian; Evangelisti, Luca; Caminati, Walther

    2017-01-01

    The rotational spectrum of the acetic acid-fluoroacetic acid bimolecule was measured by using a pulsed jet Fourier transform microwave spectrometer. One conformer, in which fluoroacetic acid is in trans form, has been observed. The rotational transitions are split into two component lines, due to the internal rotation of the methyl group of acetic acid. From these splittings, the corresponding V3 barrier has been determined. The dissociation energy of this complex has been estimated to 66 kJ/mol. An increase of the distance between the two monomers upon the OH → OD substitution (Ubbelohde effect) has been observed.

  1. Longitudinal acoustic properties of poly(lactic acid) and poly(lactic-co-glycolic acid).

    PubMed

    Parker, N G; Mather, M L; Morgan, S P; Povey, M J W

    2010-10-01

    Acoustics offers rich possibilities for characterizing and monitoring the biopolymer structures being employed in the field of biomedical engineering. Here we explore the rudimentary acoustic properties of two common biodegradable polymers: poly(lactic acid) and poly(lactic-co-glycolic acid). A pulse-echo technique is developed to reveal the bulk speed of sound, acoustic impedance and acoustic attenuation of small samples of the polymer across a pertinent temperature range of 0-70 °C. The glass transition appears markedly as both a discontinuity in the first derivative of the speed of sound and a sharp increase in the acoustic attenuation. We further extend our analysis to consider the role of ethanol, whose presence is observed to dramatically modify the acoustic properties and reduce the glass transition temperature of the polymers. Our results highlight the sensitivity of acoustic properties to a range of bulk properties, including visco-elasticity, molecular weight, co-polymer ratio, crystallinity and the presence of plasticizers.

  2. Acetic acid vapor levels associated with facial prosthetics

    SciTech Connect

    McElroy, T.H.; Guerra, O.N.; Lee, S.A.

    1985-01-01

    The use of Silastic Medical Adhesive Type A in the fabrication of facial prostheses may cause health hazards to the patient and the operator because of acetic acid emissions. Caution must be exercised to remove acetic acid vapors from the air and unliberated acetic acid from material applied directly to the skin.

  3. Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins

    ERIC Educational Resources Information Center

    Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines

    2011-01-01

    A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The…

  4. Stress responses in lactic acid bacteria.

    PubMed

    van de Guchte, Maarten; Serror, Pascale; Chervaux, Christian; Smokvina, Tamara; Ehrlich, Stanislav D; Maguin, Emmanuelle

    2002-08-01

    Lactic acid bacteria (LAB) constitute a heterogeneous group of bacteria that are traditionally used to produce fermented foods. The industrialization of food bio-transformations increased the economical importance of LAB, as they play a crucial role in the development of the organoleptique and hygienic quality of fermented products. Therefore, the reliability of starter strains in terms of quality and functional properties (important for the development of aroma and texture), but also in terms of growth performance and robustness has become essential. These strains should resist to adverse conditions encountered in industrial processes, for example during starter handling and storage (freeze-drying, freezing or spray-drying). The development of new applications such as life vaccines and probiotic foods reinforces the need for robust LAB since they may have to survive in the digestive tract, resist the intestinal flora, maybe colonize the digestive or uro-genital mucosa and express specific functions under conditions that are unfavorable to growth (for example, during stationary phase or storage). Also in nature, the ability to quickly respond to stress is essential for survival and it is now well established that LAB, like other bacteria, evolved defense mechanisms against stress that allow them to withstand harsh conditions and sudden environmental changes. While genes implicated in stress responses are numerous, in LAB the levels of characterization of their actual role and regulation differ widely between species. The functional conservation of several stress proteins (for example, HS proteins, Csp, etc) and of some of their regulators (for example, HrcA, CtsR) renders even more striking the differences that exist between LAB and the classical model micro-organisms. Among the differences observed between LAB species and B. subtilis, one of the most striking is the absence of a sigma B orthologue in L. lactis ssp. lactis as well as in at least two streptococci

  5. D-lactic acid production from cellooligosaccharides and beta-glucan using L-LDH gene-deficient and endoglucanase-secreting Lactobacillus plantarum.

    PubMed

    Okano, Kenji; Zhang, Qiao; Yoshida, Shogo; Tanaka, Tsutomu; Ogino, Chiaki; Fukuda, Hideki; Kondo, Akihiko

    2010-01-01

    In order to achieve direct fermentation of an optically pure D: -lactic acid from cellulosic materials, an endoglucanase from a Clostridium thermocellum (CelA)-secreting plasmid was introduced into an L: -lactate dehydrogenase gene (ldhL1)-deficient Lactobacillus plantarum (ldhL1) bacterial strain. CelA expression and its degradation of beta-glucan was confirmed by western blot analysis and enzyme assay, respectively. Although the CelA-secreting ldhL1 assimilated cellooligosaccharides up to cellohexaose (although not cellotetraose), the main end product was acetic acid, not lactic acid, due to the conversion of lactic acid to acetic acid. Cultivation under anaerobic conditions partially suppressed this conversion resulting in the production of 1.27 g/l of D: -lactic acid with a high optical purity of 99.5% from a medium containing 2 g/l of cellohexaose. Subsequently, D: -lactic acid fermentation from barley beta-glucan was carried out with the addition of Aspergillus aculeatus beta-glucosidase produced by recombinant Aspergillus oryzae and 1.47 g/l of D: -lactic was produced with a high optical purity of 99.7%. This is the first report of direct lactic acid fermentation from beta-glucan and a cellooligosaccharide that is a more highly polymerized sugar than cellotriose.

  6. Gut mucosal immunostimulation by lactic acid bacteria.

    PubMed

    Vitiñi, E; Alvarez, S; Medina, M; Medici, M; de Budeguer, M V; Perdigón, G

    2000-12-01

    The beneficial properties of lactic acid bacteria (LAB) on human health have been frequently demonstrated. The interaction of LAB with the lymphoid cells associated to the gut to activate the mucosal immune system and the mechanisms by which they can exert an adjuvant effect is still unclear, as well as if this property is common for all the LAB. We studied the influence of the oral administration of different geneous of LAB such as Lactobacillus casei, L. acidophilus, L. rhamnosus, L. delbrueckii subsp. bulgaricus, L. plantarum, Lactococcus lactis and Streptococcus thermophilus. We determined if the LAB assayed were able to stimulate the specific, the non-specific immune response (inflammatory response), or both. We demonstrated that all the bacteria assayed were able to increase the number of IgA producing cells associated to the lamina propria of small intestine. This effect was dose dependent. The increase in IgA+ producing cells was not always correlated with an increase in the CD4+ T cell number, indicating that some LAB assayed only induced clonal expansion of B cells triggered to produce IgA. Most of them, induced an increase in the number of cells involved in the inflammatory immune response. CD8+ T cell were diminished or not affected, with exception of L. plantarum that induced an increase at low dose. This fact would mean that LAB are unable to induce cytotoxicity mechanisms. We demonstrated the importance in the selection of LAB to be used as gut mucosal adjuvant. The different behaviours observed among them on the gut mucosal immune response, specially those that induce inflammatory immune response, show that not all the LAB can be used as oral adjuvant and that the beneficial effect of them can not generalized to genous or specie. The immunoadjuvant capacity would be a property of the strain assayed.

  7. Separating acetic acid from furol (furfural) by electrodialysis method

    SciTech Connect

    Guan, S.F.; Li, C.S. Ye, S.T.; Shen, S.Y.; Wang, Y.T.; Yu, S.H.

    1981-01-01

    Furfural production by hydrolysis of fibrous plant materials is accompanied by formation of acetic acid in amounts depending on the material used. The amount of acetic formed in the hydrolysis of the fruit shell of oil-tea camellia (Camellia oleosa) (an oilseed-bearing tree) is equal to the amount of furfural. The acetic acid can be separated from the furfural and concentrated to 10% by electrodialysis. A smaller amount of furfural is separated with acetic acid.

  8. Overexpression of ESBP6 improves lactic acid resistance and production in Saccharomyces cerevisiae.

    PubMed

    Sugiyama, Minetaka; Akase, Shin-Pei; Nakanishi, Ryota; Kaneko, Yoshinobu; Harashima, Satoshi

    2016-10-01

    Polylactic acid plastics are receiving increasing attention for the control of atmospheric CO2 emissions. Lactic acid, the building block for polylactic acid, is produced by fermentation technology from renewable carbon sources. The yeast Saccharomyces cerevisiae, harboring the lactate dehydrogenases gene (LDH), produces lactic acid at a large scale due to its strong acid resistance, to its simple nutritional requirements and to its ease of genetic engineering. Since improvement of lactic acid resistance is correlated with an increase of lactic acid production under non-neutralizing condition, we isolated a novel gene that enhances lactic acid resistance using a multi-copy yeast genomic DNA library. In this study, we identified the ESBP6 gene, which increases lactic acid resistance when overexpressed and which encodes a protein with similarity to monocarboxylate permeases. Although ESBP6 was not induced in response to lactic acid stress, it caused weak but reproducible sensitivity to lactic acid when disrupted. Furthermore, intracellular pH in the ESBP6 overexpressing strain was higher than that in the wild-type strain under lactic acid stressed condition, suggesting that Esbp6 plays some roles in lactic acid adaptation response. The ESBP6 overexpressing strain carrying the LDH gene induced 20% increase in lactic acid production compared with the wild-type strain carrying the LDH gene under non-neutralizing conditions. These results indicate that overexpression of ESBP6 provides a novel and useful tool to improve lactic acid resistance and lactic acid production in yeast.

  9. Adaptation and tolerance of bacteria against acetic acid.

    PubMed

    Trček, Janja; Mira, Nuno Pereira; Jarboe, Laura R

    2015-08-01

    Acetic acid is a weak organic acid exerting a toxic effect to most microorganisms at concentrations as low as 0.5 wt%. This toxic effect results mostly from acetic acid dissociation inside microbial cells, causing a decrease of intracellular pH and metabolic disturbance by the anion, among other deleterious effects. These microbial inhibition mechanisms enable acetic acid to be used as a preservative, although its usefulness is limited by the emergence of highly tolerant spoilage strains. Several biotechnological processes are also inhibited by the accumulation of acetic acid in the growth medium including production of bioethanol from lignocellulosics, wine making, and microbe-based production of acetic acid itself. To design better preservation strategies based on acetic acid and to improve the robustness of industrial biotechnological processes limited by this acid's toxicity, it is essential to deepen the understanding of the underlying toxicity mechanisms. In this sense, adaptive responses that improve tolerance to acetic acid have been well studied in Escherichia coli and Saccharomyces cerevisiae. Strains highly tolerant to acetic acid, either isolated from natural environments or specifically engineered for this effect, represent a unique reservoir of information that could increase our understanding of acetic acid tolerance and contribute to the design of additional tolerance mechanisms. In this article, the mechanisms underlying the acetic acid tolerance exhibited by several bacterial strains are reviewed, with emphasis on the knowledge gathered in acetic acid bacteria and E. coli. A comparison of how these bacterial adaptive responses to acetic acid stress fit to those described in the yeast Saccharomyces cerevisiae is also performed. A systematic comparison of the similarities and dissimilarities of the ways by which different microbial systems surpass the deleterious effects of acetic acid toxicity has not been performed so far, although such exchange

  10. Selection of tropical lactic acid bacteria for enhancing the quality of maize silage.

    PubMed

    Santos, A O; Ávila, C L S; Schwan, R F

    2013-01-01

    The objective of this study was to select lactic acid bacteria (LAB) strains isolated from silage and assess their effect on the quality of maize silage. The LAB strains were inoculated into aqueous extract obtained from maize to evaluate their production of metabolites and pH reduction. The ability to inhibit the pathogenic and silage-spoilage microorganisms' growth was evaluated. Nine LAB strains that showed the best results were assessed in polyvinyl chloride experimental silos. The inoculation of the LAB strains influenced the concentration of lactic and acetic acids and the diversity of Listeria. The inoculation of silages with Lactobacillus buchneri (UFLA SLM11 and UFLA SLM103 strains) resulted in silages with greater LAB populations and improvements after aerobic exposure. The UFLA SLM11 and SLM103 strains identified as L. buchneri showed to be promising in the treatment of maize silage.

  11. Citric acid metabolism in hetero- and homofermentative lactic acid bacteria.

    PubMed Central

    Drinan, D F; Robin, S; Cogan, T M

    1976-01-01

    The effect of citrate on production of diacetyl and acetoin by four strains each of heterofermentative and homofermentative lactic acid bacteria capable of utilizing citrate was studied. Acetoin was quantitatively the more important compound. The heterofermentative bacteria produced no acetoin or diacetyl in the absence of citrate, and two strains produced traces of acetoin in its presence. Citrate stimulated the growth rate of the heterofermentative lactobacilli. Acidification of all heterofermentative cultures with citric acid resulted in acetoin production. Destruction of accumulated acetoin appeared to coincide with the disappearance of citrate. All homofermentative bacteria produced more acetoin and diacetyl in the presence of citrate than in its absence. Citrate utilization was begun immediately by the streptococci but was delayed until at least the middle of the exponential phase in the case of the lactobacilli. PMID:5054

  12. Functional genomics of lactic acid bacteria: from food to health

    PubMed Central

    2014-01-01

    Genome analysis using next generation sequencing technologies has revolutionized the characterization of lactic acid bacteria and complete genomes of all major groups are now available. Comparative genomics has provided new insights into the natural and laboratory evolution of lactic acid bacteria and their environmental interactions. Moreover, functional genomics approaches have been used to understand the response of lactic acid bacteria to their environment. The results have been instrumental in understanding the adaptation of lactic acid bacteria in artisanal and industrial food fermentations as well as their interactions with the human host. Collectively, this has led to a detailed analysis of genes involved in colonization, persistence, interaction and signaling towards to the human host and its health. Finally, massive parallel genome re-sequencing has provided new opportunities in applied genomics, specifically in the characterization of novel non-GMO strains that have potential to be used in the food industry. Here, we provide an overview of the state of the art of these functional genomics approaches and their impact in understanding, applying and designing lactic acid bacteria for food and health. PMID:25186768

  13. Functional genomics of lactic acid bacteria: from food to health.

    PubMed

    Douillard, François P; de Vos, Willem M

    2014-08-29

    Genome analysis using next generation sequencing technologies has revolutionized the characterization of lactic acid bacteria and complete genomes of all major groups are now available. Comparative genomics has provided new insights into the natural and laboratory evolution of lactic acid bacteria and their environmental interactions. Moreover, functional genomics approaches have been used to understand the response of lactic acid bacteria to their environment. The results have been instrumental in understanding the adaptation of lactic acid bacteria in artisanal and industrial food fermentations as well as their interactions with the human host. Collectively, this has led to a detailed analysis of genes involved in colonization, persistence, interaction and signaling towards to the human host and its health. Finally, massive parallel genome re-sequencing has provided new opportunities in applied genomics, specifically in the characterization of novel non-GMO strains that have potential to be used in the food industry. Here, we provide an overview of the state of the art of these functional genomics approaches and their impact in understanding, applying and designing lactic acid bacteria for food and health.

  14. A sulfuric-lactic acid process for efficient purification of fungal chitosan with intact molecular weight.

    PubMed

    Naghdi, Mitra; Zamani, Akram; Karimi, Keikhosro

    2014-02-01

    The most recent method of fungal chitosan purification, i.e., two steps of dilute sulfuric acid treatment, pretreatment of cell wall at room temperature for phosphate removal and extraction of chitosan from the phosphate free cell wall at high temperature, significantly reduces the chitosan molecular weight. This study was aimed at improvement of this method. In the pretreatment step, to choose the best conditions, cell wall of Rhizopus oryzae, containing 9% phosphate, 10% glucosamine, and 21% N-acetyl glucosamine, was treated with sulfuric, lactic, acetic, nitric, or hydrochloric acid, at room temperature. Sulfuric acid showed the best performance in phosphate removal (90%) and cell wall recovery (89%). To avoid depolymerisation of chitosan, hot sulfuric acid extraction was replaced with lactic acid treatment at room temperature, and a pure fungal chitosan was obtained (0.12 g/g cell wall). Similar pretreatment and extraction processes were conducted on pure shrimp chitosan and resulted in a chitosan recovery of higher than 87% while the reduction of chitosan viscosity was less than 15%. Therefore, the sulfuric-lactic acid method purified the fungal chitosan without significant molecular weight manipulation.

  15. Importance of lactic acid bacteria in Asian fermented foods

    PubMed Central

    2011-01-01

    Lactic acid bacteria play important roles in various fermented foods in Asia. Besides being the main component in kimchi and other fermented foods, they are used to preserve edible food materials through fermentation of other raw-materials such as rice wine/beer, rice cakes, and fish by producing organic acids to control putrefactive microorganisms and pathogens. These bacteria also provide a selective environment favoring fermentative microorganisms and produce desirable flavors in various fermented foods. This paper discusses the role of lactic acid bacteria in various non-dairy fermented food products in Asia and their nutritional and physiological functions in the Asian diet. PMID:21995342

  16. Recovery of very dilute acetic acid using ion exchange

    SciTech Connect

    Cloete, F.L.D.; Marais, A.P.

    1995-07-01

    Acetic and related acids occur in many industrial wastewaters, often mixed with several other classes of organic compounds. Acetic acid can be recovered from 1% solutions using weakly basic ion exchange resins. The acid is adsorbed by the free-base form of the resin, which can then be eluted using a slurry of lime to give a solution of calcium acetate. This solution could either be evaporated to crystallize calcium acetate or reacted with sulfuric acid to form acetic acid and gypsum. Laboratory tests of the proposed process gave product solutions of 15--20% acetic acid using pure 1% acetic acid as feed. Some measurements using a typical industrial effluent gave similar recoveries and showed that there was no initial fouling of the resins.

  17. Disruption of multiple genes whose deletion causes lactic-acid resistance improves lactic-acid resistance and productivity in Saccharomyces cerevisiae.

    PubMed

    Suzuki, Toshihiro; Sakamoto, Takatoshi; Sugiyama, Minetaka; Ishida, Nobuhiro; Kambe, Hiromi; Obata, Shusei; Kaneko, Yoshinobu; Takahashi, Haruo; Harashima, Satoshi

    2013-05-01

    To create strains that have high productivity of lactic acid without neutralization, a genome-wide screening for strains showing hyper-resistance to 6% l-lactic acid (pH 2.6) was performed using the gene deletion collection of Saccharomyces cerevisiae. We identified 94 genes whose disruption led to resistance to 6% lactic acid in rich medium. We also found that multiple combinations of Δdse2, Δscw11, Δeaf3, and/or Δsed1 disruption led to enhanced resistance to lactic acid depending upon their combinations. In particular, the quadruple disruptant Δdse2Δscw11Δeaf3Δsed1 grew well in 6% lactic acid with the shortest lag phase. We then introduced an exogenous lactate dehydrogenase gene (LDH) into those single and multiple disruptants to evaluate their productivity of lactic acid. It was found that the quadruple disruptant displaying highest lactic-acid resistance showed a 27% increase of lactic-acid productivity as compared with the LDH-harboring wild-type strain. These observations suggest that disruption of multiple genes whose deletion leads to lactic-acid resistance is an effective way to enhance resistance to lactic acid, leading to high lactic-acid productivity without neutralization.

  18. Sphingolipids contribute to acetic acid resistance in Zygosaccharomyces bailii.

    PubMed

    Lindahl, Lina; Genheden, Samuel; Eriksson, Leif A; Olsson, Lisbeth; Bettiga, Maurizio

    2016-04-01

    Lignocellulosic raw material plays a crucial role in the development of sustainable processes for the production of fuels and chemicals. Weak acids such as acetic acid and formic acid are troublesome inhibitors restricting efficient microbial conversion of the biomass to desired products. To improve our understanding of weak acid inhibition and to identify engineering strategies to reduce acetic acid toxicity, the highly acetic-acid-tolerant yeast Zygosaccharomyces bailii was studied. The impact of acetic acid membrane permeability on acetic acid tolerance in Z. bailii was investigated with particular focus on how the previously demonstrated high sphingolipid content in the plasma membrane influences acetic acid tolerance and membrane permeability. Through molecular dynamics simulations, we concluded that membranes with a high content of sphingolipids are thicker and more dense, increasing the free energy barrier for the permeation of acetic acid through the membrane. Z. bailii cultured with the drug myriocin, known to decrease cellular sphingo-lipid levels, exhibited significant growth inhibition in the presence of acetic acid, while growth in medium without acetic acid was unaffected by the myriocin addition. Furthermore, following an acetic acid pulse, the intracellular pH decreased more in myriocin-treated cells than in control cells. This indicates a higher inflow rate of acetic acid and confirms that the reduction in growth of cells cultured with myriocin in the medium with acetic acid was due to an increase in membrane permeability, thereby demonstrating the importance of a high fraction of sphingolipids in the membrane of Z. bailii to facilitate acetic acid resistance; a property potentially transferable to desired production organisms suffering from weak acid stress.

  19. Isolation of acetic, propionic and butyric acid-forming bacteria from biogas plants.

    PubMed

    Cibis, Katharina Gabriela; Gneipel, Armin; König, Helmut

    2016-02-20

    In this study, acetic, propionic and butyric acid-forming bacteria were isolated from thermophilic and mesophilic biogas plants (BGP) located in Germany. The fermenters were fed with maize silage and cattle or swine manure. Furthermore, pressurized laboratory fermenters digesting maize silage were sampled. Enrichment cultures for the isolation of acid-forming bacteria were grown in minimal medium supplemented with one of the following carbon sources: Na(+)-dl-lactate, succinate, ethanol, glycerol, glucose or a mixture of amino acids. These substrates could be converted by the isolates to acetic, propionic or butyric acid. In total, 49 isolates were obtained, which belonged to the phyla Firmicutes, Tenericutes or Thermotogae. According to 16S rRNA gene sequences, most isolates were related to Clostridium sporosphaeroides, Defluviitoga tunisiensis and Dendrosporobacter quercicolus. Acetic, propionic or butyric acid were produced in cultures of isolates affiliated to Bacillus thermoamylovorans, Clostridium aminovalericum, Clostridium cochlearium/Clostridium tetani, C. sporosphaeroides, D. quercicolus, Proteiniborus ethanoligenes, Selenomonas bovis and Tepidanaerobacter sp. Isolates related to Thermoanaerobacterium thermosaccharolyticum produced acetic, butyric and lactic acid, and isolates related to D. tunisiensis formed acetic acid. Specific primer sets targeting 16S rRNA gene sequences were designed and used for real-time quantitative PCR (qPCR). The isolates were physiologically characterized and their role in BGP discussed.

  20. Genetic Engineering of Rhizopus for Enhancing Lactic Acid Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Rhizopus is frequently used to convert, or ferment sugars obtained from agricultural crops to lactic acid. This natural product has long been utilized by the food industry as an additive for preservation, flavor, and acidity. Additionally, it is used for the manufacture of environmental...

  1. Isolation of lactic acid-forming bacteria from biogas plants.

    PubMed

    Bohn, Jelena; Yüksel-Dadak, Aytül; Dröge, Stefan; König, Helmut

    2017-02-20

    Direct molecular approaches provide hints that lactic acid bacteria play an important role in the degradation process of organic material to methanogenetic substrates in biogas plants. However, their diversity in biogas fermenter samples has not been analyzed in detail yet. For that reason, five different biogas fermenters, which were fed mainly with maize silage and manure from cattle or pigs, were examined for the occurrence of lactic acid-forming bacteria. A total of 197 lactic acid-forming bacterial strains were isolated, which we assigned to 21 species, belonging to the genera Bacillus, Clostridium, Lactobacillus, Pediococcus, Streptococcus and Pseudoramibacter-related. A qualitative multiplex system and a real-time quantitative PCR could be developed for most isolates, realized by the selection of specific primers. Their role in biogas plants was discussed on the basis of the quantitative results and on physiological data of the isolates.

  2. Production of L-lactic Acid from Biomass Wastes Using Scallop Crude Enzymes and Novel Lactic Acid Bacterium

    NASA Astrophysics Data System (ADS)

    Yanagisawa, Mitsunori; Nakamura, Kanami; Nakasaki, Kiyohiko

    In the present study, biomass waste raw materials including paper mill sludge, bamboo, sea lettuce, and shochu residue (from a distiller) and crude enzymes derived from inedible and discarded scallop parts were used to produce L-lactic acid for the raw material of biodegradable plastic poly-lactic acid. The activities of cellulase and amylase in the crude enzymes were 22 and 170units/L, respectively, and L-lactic acid was produced from every of the above mentioned biomass wastes, by the method of liquid-state simultaneous saccharification and fermentation (SSF) . The L-lactic acid concentrations produced from sea lettuce and shochu residue, which contain high concentration of starch were 3.6 and 9.3g/L, respectively, and corresponded to greater than 25% of the conversion of glucans contained in these biomass wastes. Furthermore, using the solid state SSF method, concentrations as high as 13g/L of L-lactic acid were obtained from sea lettuce and 26g/L were obtained from shochu residue.

  3. Utilization of lactic acid bacterial genes in Synechocystis sp. PCC 6803 in the production of lactic acid.

    PubMed

    Joseph, Ancy; Aikawa, Shimpei; Sasaki, Kengo; Tsuge, Yota; Matsuda, Fumio; Tanaka, Tsutomu; Kondo, Akihiko

    2013-01-01

    Metabolic pathway engineering of cyanobacteria for the production of industrially important chemicals from atmospheric CO2 has generated interest recently. Here, we engineered Synechocystis sp. PCC 6803 to produce lactic acid using a lactate dehydrogenase (ldh) gene from various lactic acid-producing bacteria, Lactococcus lactis (ldhB and ldhX), Lactobacillus plantarum (ldhL and ldh), and Lactobacillus rhamnosus (ldhL). The lactic acid was secreted outside the cell using a transporter (lldp) gene from L. plantarum. Expression of each ldh in Synechocystis sp. PCC6803 was ascertained by reverse-transcriptase polymerase chain reaction. Five transformants led to the production of L-lactic acid. Co-expression of lldp with ldhB from L. plantarum or ldhL from L. rhamnosus led to the secretion of lactic acid into the medium at concentration of 0.17 ± 0.02 or 0.14 ± 0.02 mM after 18 d of cultivation.

  4. Lactic acid bacteria in the quality improvement and depreciation of wine.

    PubMed

    Lonvaud-Funel, A

    1999-01-01

    The winemaking process includes two main steps: lactic acid bacteria are responsible for the malolactic fermentation which follows the alcoholic fermentation by yeasts. Both types of microorganisms are present on grapes and on cellar equipment. Yeasts are better adapted to growth in grape must than lactic acid bacteria, so the alcoholic fermentation starts quickly. In must, up to ten lactic acid bacteria species can be identified. They belong to the Lactobacillus, Pediococcus, Leuconostoc and Oenococcus genera. Throughout alcoholic fermentation, a natural selection occurs and finally the dominant species is O. oeni, due to interactions between yeasts and bacteria and between bacteria themselves. After bacterial growth, when the population is over 10(6) CFU/ml, malolactic transformation is the obvious change in wine composition. However, many other substrates can be metabolized. Some like remaining sugars and citric acid are always assimilated by lactic acid bacteria, thus providing them with energy and carbon. Other substrates such as some amino acids may be used following pathways restricted to strains carrying the adequate enzymes. Some strains can also produce exopolysaccharides. All these transformations greatly influence the sensory and hygienic quality of wine. Malic acid transformation is encouraged because it induces deacidification. Diacetyl produced from citric acid is also helpful to some extent. Sensory analyses show that many other reactions change the aromas and make malolactic fermentation beneficial, but they are as yet unknown. On the contrary, an excess of acetic acid, the synthesis of glucane, biogenic amines and precursors of ethylcarbamate are undesirable. Fortunately, lactic acid bacteria normally multiply in dry wines; moreover some of these activities are not widespread. Moreover, the most striking trait of wine lactic acid bacteria is their capacity to adapt to a hostile environment. The mechanisms for this are not yet completely elucidated

  5. Molecular screening of wine lactic acid bacteria degrading hydroxycinnamic acids.

    PubMed

    de las Rivas, Blanca; Rodríguez, Héctor; Curiel, José Antonio; Landete, José María; Muñoz, Rosario

    2009-01-28

    The potential to produce volatile phenols from hydroxycinnamic acids was investigated for lactic acid bacteria (LAB) isolated from Spanish grape must and wine. A PCR assay was developed for the detection of LAB that potentially produce volatile phenols. Synthetic degenerate oligonucleotides for the specific detection of the pdc gene encoding a phenolic acid decarboxylase were designed. The pdc PCR assay amplifies a 321 bp DNA fragment from phenolic acid decarboxylase. The pdc PCR method was applied to 85 strains belonging to the 6 main wine LAB species. Lactobacillus plantarum, Lactobacillus brevis, and Pediococcus pentosaceus strains produce a positive response in the pdc PCR assay, whereas Oenococcus oeni, Lactobacillus hilgardii, and Leuconostoc mesenteroides strains did not produce the expected PCR product. The production of vinyl and ethyl derivatives from hydroxycinnamic acids in culture media was determined by high-performance liquid chromatography. A relationship was found between pdc PCR amplification and volatile phenol production, so that the LAB strains that gave a positive pdc PCR response produce volatile phenols, whereas strains that did not produce a PCR amplicon did not produce volatile phenols. The proposed method could be useful for a preliminary identification of LAB strains able to produce volatile phenols in wine.

  6. Lactic Acid and Biosurfactants Production from Residual Cellulose Films.

    PubMed

    Portilla Rivera, Oscar Manuel; Arzate Martínez, Guillermo; Jarquín Enríquez, Lorenzo; Vázquez Landaverde, Pedro Alberto; Domínguez González, José Manuel

    2015-11-01

    The increasing amounts of residual cellulose films generated as wastes all over the world represent a big scale problem for the meat industry regarding to environmental and economic issues. The use of residual cellulose films as a feedstock of glucose-containing solutions by acid hydrolysis and further fermentation into lactic acid and biosurfactants was evaluated as a method to diminish and revalorize these wastes. Under a treatment consisting in sulfuric acid 6% (v/v); reaction time 2 h; solid liquid ratio 9 g of film/100 mL of acid solution, and temperature 130 °C, 35 g/L of glucose and 49% of solubilized film was obtained. From five lactic acid strains, Lactobacillus plantarum was the most suitable for metabolizing the glucose generated. The process was scaled up under optimized conditions in a 2-L bioreactor, producing 3.4 g/L of biomass, 18 g/L of lactic acid, and 15 units of surface tension reduction of a buffer phosphate solution. Around 50% of the cellulose was degraded by the treatment applied, and the liqueurs generated were useful for an efficient production of lactic acid and biosurfactants using L. plantarum. Lactobacillus bacteria can efficiently utilize glucose from cellulose films hydrolysis without the need of clarification of the liqueurs.

  7. Lactose behaviour in the presence of lactic acid and calcium.

    PubMed

    Wijayasinghe, Rangani; Vasiljevic, Todor; Chandrapala, Jayani

    2016-08-01

    Physical properties of lactose appeared influenced by presence of lactic acid in the system. Some other components such as Ca may further attenuate lactose behaviour and impact its phase transition. A model-based study was thus implemented with varying concentrations of Ca (0·12, 0·072 or 0·035% w/w) and lactic acid (0·05, 0·2, 0·4 or 1% w/w) in establishing the effects of these two main acid whey constituents on lactose phase behaviour. Concentrated solutions (50% w/w) containing lactose, lactic acid and Ca were analysed for thermal behaviour and structural changes by Differential Scanning Colorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR), respectively. Presence of 1% (w/w) lactic acid and 0·12% (w/w) Ca in lactose solution significantly increased the evaporation enthalpy of water, delayed and increased the energy required for lactose crystallisation as compared to pure lactose. FTIR analysis indicated a strong hydration layer surrounding lactose molecules, restricting water mobility and/or inducing structural changes of lactose, hindering its crystallisation. The formation of calcium lactate, which restricts the diffusion of lactose molecules, is also partly responsible. It appears that Ca removal from acid whey may be a necessary step in improving the processability of acid whey.

  8. 40 CFR 180.1090 - Lactic acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Lactic acid; exemption from the... Exemptions From Tolerances § 180.1090 Lactic acid; exemption from the requirement of a tolerance. Lactic acid (2-hydroxypropanoic acid) is exempted from the requirement of a tolerance when used as a plant...

  9. Lactic acid production from xylose by the fungus Rhizopus oryzae.

    PubMed

    Maas, Ronald H W; Bakker, Robert R; Eggink, Gerrit; Weusthuis, Ruud A

    2006-10-01

    Lignocellulosic biomass is considered nowadays to be an economically attractive carbohydrate feedstock for large-scale fermentation of bulk chemicals such as lactic acid. The filamentous fungus Rhizopus oryzae is able to grow in mineral medium with glucose as sole carbon source and to produce optically pure L(+)-lactic acid. Less is known about the conversion by R. oryzae of pentose sugars such as xylose, which is abundantly present in lignocellulosic hydrolysates. This paper describes the conversion of xylose in synthetic media into lactic acid by ten R. oryzae strains resulting in yields between 0.41 and 0.71 g g(-1). By-products were fungal biomass, xylitol, glycerol, ethanol and carbon dioxide. The growth of R. oryzae CBS 112.07 in media with initial xylose concentrations above 40 g l(-1) showed inhibition of substrate consumption and lactic acid production rates. In case of mixed substrates, diauxic growth was observed where consumption of glucose and xylose occurred subsequently. Sugar consumption rate and lactic acid production rate were significantly higher during glucose consumption phase compared to xylose consumption phase. Available xylose (10.3 g l(-1)) and glucose (19.2 g l(-1)) present in a mild-temperature alkaline treated wheat straw hydrolysate was converted subsequently by R. oryzae with rates of 2.2 g glucose l(-1) h(-1) and 0.5 g xylose l(-1) h(-1). This resulted mainly into the product lactic acid (6.8 g l(-1)) and ethanol (5.7 g l(-1)).

  10. Isolating and evaluating lactic acid bacteria strains for effectiveness of Leymus chinensis silage fermentation.

    PubMed

    Zhang, Q; Li, X J; Zhao, M M; Yu, Z

    2014-10-01

    Five LAB strains were evaluated using the acid production ability test, morphological observation, Gram staining, physiological, biochemical and acid tolerance tests. All five strains (LP1, LP2, LP3, LC1 and LC2) grew at pH 4·0, and LP1 grew at 15°C. Strains LP1, LP2 and LP3 were identified as Lactobacillus plantarum, whereas LC1 and LC2 were classified as Lactobacillus casei by sequencing 16S rDNA. The five isolated strains and two commercial inoculants (PS and CL) were added to native grass and Leymus chinensis (Trin.) Tzvel. for ensiling. All five isolated strains decreased the pH and ammonia nitrogen content, increased the lactic acid content and LP1, LP2 and LP3 increased the acetic content and lactic/acetic acid ratio of L. chinensis silage significantly. The five isolated strains and two commercial inoculants decreased the butyric acid content of the native grass silage. LP2 treatment had lower butyric acid content and ammonia nitrogen content than the other treatments. The five isolated strains improved the quality of L. chinensis silage. The five isolated strains and the two commercial inoculants were not effective in improving the fermentation quality of the native grass silage, but LP2 performed better comparatively. Significance and impact of the study: Leymus chinensis is an important grass in China and Russia, being the primary grass of the short grassland 'steppe' regions of central Asia. However, it has been difficult to make high-quality silage of this species because of low concentration of water-soluble carbohydrates (WSC). Isolating and evaluating lactic acid bacteria strains will be helpful for improving the silage quality of this extensively grown species.

  11. Antimicrobial and immune modulatory effects of lactic acid and short chain fatty acids produced by vaginal microbiota associated with eubiosis and bacterial vaginosis.

    PubMed

    Aldunate, Muriel; Srbinovski, Daniela; Hearps, Anna C; Latham, Catherine F; Ramsland, Paul A; Gugasyan, Raffi; Cone, Richard A; Tachedjian, Gilda

    2015-01-01

    Lactic acid and short chain fatty acids (SCFAs) produced by vaginal microbiota have reported antimicrobial and immune modulatory activities indicating their potential as biomarkers of disease and/or disease susceptibility. In asymptomatic women of reproductive-age the vaginal microbiota is comprised of lactic acid-producing bacteria that are primarily responsible for the production of lactic acid present at ~110 mM and acidifying the vaginal milieu to pH ~3.5. In contrast, bacterial vaginosis (BV), a dysbiosis of the vaginal microbiota, is characterized by decreased lactic acid-producing microbiota and increased diverse anaerobic bacteria accompanied by an elevated pH>4.5. BV is also characterized by a dramatic loss of lactic acid and greater concentrations of mixed SCFAs including acetate, propionate, butyrate, and succinate. Notably women with lactic acid-producing microbiota have more favorable reproductive and sexual health outcomes compared to women with BV. Regarding the latter, BV is associated with increased susceptibility to sexually transmitted infections (STIs) including HIV. In vitro studies demonstrate that lactic acid produced by vaginal microbiota has microbicidal and virucidal activities that may protect against STIs and endogenous opportunistic bacteria as well as immune modulatory properties that require further characterization with regard to their effects on the vaginal mucosa. In contrast, BV-associated SCFAs have far less antimicrobial activity with the potential to contribute to a pro-inflammatory vaginal environment. Here we review the composition of lactic acid and SCFAs in respective states of eubiosis (non-BV) or dysbiosis (BV), their effects on susceptibility to bacterial/viral STIs and whether they have inherent microbicidal/virucidal and immune modulatory properties. We also explore their potential as biomarkers for the presence and/or increased susceptibility to STIs.

  12. Antimicrobial and immune modulatory effects of lactic acid and short chain fatty acids produced by vaginal microbiota associated with eubiosis and bacterial vaginosis

    PubMed Central

    Aldunate, Muriel; Srbinovski, Daniela; Hearps, Anna C.; Latham, Catherine F.; Ramsland, Paul A.; Gugasyan, Raffi; Cone, Richard A.; Tachedjian, Gilda

    2015-01-01

    Lactic acid and short chain fatty acids (SCFAs) produced by vaginal microbiota have reported antimicrobial and immune modulatory activities indicating their potential as biomarkers of disease and/or disease susceptibility. In asymptomatic women of reproductive-age the vaginal microbiota is comprised of lactic acid-producing bacteria that are primarily responsible for the production of lactic acid present at ~110 mM and acidifying the vaginal milieu to pH ~3.5. In contrast, bacterial vaginosis (BV), a dysbiosis of the vaginal microbiota, is characterized by decreased lactic acid-producing microbiota and increased diverse anaerobic bacteria accompanied by an elevated pH>4.5. BV is also characterized by a dramatic loss of lactic acid and greater concentrations of mixed SCFAs including acetate, propionate, butyrate, and succinate. Notably women with lactic acid-producing microbiota have more favorable reproductive and sexual health outcomes compared to women with BV. Regarding the latter, BV is associated with increased susceptibility to sexually transmitted infections (STIs) including HIV. In vitro studies demonstrate that lactic acid produced by vaginal microbiota has microbicidal and virucidal activities that may protect against STIs and endogenous opportunistic bacteria as well as immune modulatory properties that require further characterization with regard to their effects on the vaginal mucosa. In contrast, BV-associated SCFAs have far less antimicrobial activity with the potential to contribute to a pro-inflammatory vaginal environment. Here we review the composition of lactic acid and SCFAs in respective states of eubiosis (non-BV) or dysbiosis (BV), their effects on susceptibility to bacterial/viral STIs and whether they have inherent microbicidal/virucidal and immune modulatory properties. We also explore their potential as biomarkers for the presence and/or increased susceptibility to STIs. PMID:26082720

  13. ASIC3: a lactic acid sensor for cardiac pain.

    PubMed

    Immke, D C; McCleskey, E W

    2001-10-05

    Angina, the prototypic vasoocclusive pain, is a radiating chest pain that occurs when heart muscle gets insufficient blood because of coronary artery disease. Other examples of vasoocclusive pain include the acute pain of heart attack and the intermittent pains that accompany sickle cell anemia and peripheral artery disease. All these conditions cause ischemia - insufficient oxygen delivery for local metabolic demand - and this releases lactic acid as cells switch to anaerobic metabolism. Recent discoveries demonstrate that sensory neurons innervating the heart are richly endowed with an ion channel that is opened by, and perfectly tuned for, the lactic acid released by muscle ischemia.

  14. Submillimeter wave spectrum of acetic acid

    NASA Astrophysics Data System (ADS)

    Ilyushin, Vadim V.; Endres, Christian P.; Lewen, Frank; Schlemmer, Stephan; Drouin, Brian J.

    2013-08-01

    We present a new global study of the submillimeter wave spectrum of the lowest three torsional states of acetic acid (CH3COOH). New measurements involving torsion-rotation transitions with J up to 79 and Ka up to 44 have been carried out between 230 and 845 GHz using the submillimeter wave spectrometers in University of Cologne and Jet Propulsion Laboratory. The new data were combined with previously published measurements and fitted using the rho-axis-method torsion-rotation Hamiltonian. The final fit used 93 parameters to give an overall weighted root-mean-square deviation of 0.85 for a dataset consisting of 7543, 6087, and 5171 transitions belonging, respectively, to the ground, first, and second excited torsional states and 1888 Δvt ≠ 0 transitions. This investigation presents more than a twofold expansion both in the J quantum number and frequency range coverage of the acetic acid spectrum. Numerous inter-torsional interactions have been observed. Furthermore, this is the highest J value ever treated with the rho-axis-method and provides a good test case for the theoretical model in use.

  15. Lactic acid fermentation from food waste with indigenous microbiota: Effects of pH, temperature and high OLR.

    PubMed

    Tang, Jialing; Wang, Xiaochang; Hu, Yisong; Zhang, Yongmei; Li, Yuyou

    2016-06-01

    The effects of pH, temperature and high organic loading rate (OLR) on lactic acid production from food waste without extra inoculum addition were investigated in this study. Using batch experiments, the results showed that although the hydrolysis rate increased with pH adjustment, the lactic acid concentration and productivity were highest at pH 6. High temperatures were suitable for solubilization but seriously restricted the acidification processes. The highest lactic acid yield (0.46g/g-TS) and productivity (278.1mg/Lh) were obtained at 37°C and pH 6. In addition, the lactic acid concentration gradually increased with the increase in OLR, and the semi-continuous reactor could be stably operated at an OLR of 18g-TS/Ld. However, system instability, low lactic acid yield and a decrease in VS removal were noticed at high OLRs (22g-TS/Ld). The concentrations of volatile fatty acids (VFAs) in the fermentation mixture were relatively low but slightly increased with OLR, and acetate was the predominant VFA component. Using high-throughput pyrosequencing, Lactobacillus from the raw food waste was found to selectively accumulate and become dominant in the semi-continuous reactor.

  16. Lactic acid production from biomass-derived sugars via co-fermentation of Lactobacillus brevis and Lactobacillus plantarum.

    PubMed

    Zhang, Yixing; Vadlani, Praveen V

    2015-06-01

    Lignocellulosic biomass is an attractive alternative resource for producing chemicals and fuels. Xylose is the dominating sugar after hydrolysis of hemicellulose in the biomass, but most microorganisms either cannot ferment xylose or have a hierarchical sugar utilization pattern in which glucose is consumed first. To overcome this barrier, Lactobacillus brevis ATCC 367 was selected to produce lactic acid. This strain possesses a relaxed carbon catabolite repression mechanism that can use glucose and xylose simultaneously; however, lactic acid yield was only 0.52 g g(-1) from a mixture of glucose and xylose, and 5.1 g L(-1) of acetic acid and 8.3 g L(-1) of ethanol were also formed during production of lactic acid. The yield was significantly increased and ethanol production was significantly reduced if L. brevis was co-cultivated with Lactobacillus plantarum ATCC 21028. L. plantarum outcompeted L. brevis in glucose consumption, meaning that L. brevis was focused on converting xylose to lactic acid and the by-product, ethanol, was reduced due to less NADH generated in the fermentation system. Sequential co-fermentation of L. brevis and L. plantarum increased lactic acid yield to 0.80 g g(-1) from poplar hydrolyzate and increased yield to 0.78 g lactic acid per g of biomass from alkali-treated corn stover with minimum by-product formation. Efficient utilization of both cellulose and hemicellulose components of the biomass will improve overall lactic acid production and enable an economical process to produce biodegradable plastics.

  17. Tested Demonstrations: Buffer Capacity of Various Acetic Acid-Sodium Acetate Systems: A Lecture Experiment.

    ERIC Educational Resources Information Center

    Donahue, Craig J.; Panek, Mary G.

    1985-01-01

    Background information and procedures are provided for a lecture experiment which uses indicators to illustrate the concept of differing buffer capacities by titrating acetic acid/sodium acetate buffers with 1.0 molar hydrochloric acid and 1.0 molar sodium hydroxide. A table with data used to plot the titration curve is included. (JN)

  18. Differential titration of bases in glacial acetic acid.

    PubMed

    Castellano, T; Medwick, T; Shinkai, J H; Bailey, L

    1981-01-01

    A study of bases in acetic acid and their differential titration was carried out. The overall basicity constants for 20 bases were measured in acetic acid, and the differential titration of five binary mixtures of variable delta pKb values in acetic acid was followed using a glass electrode-modified calomel electrode system. Agreement with literature values was good. A leveling diagram was constructed that indicated that bases stronger than aqueous pKb 10 are leveled to an acetous pKb 5.69, whereas weaker bases are not leveled but instead exhibit their own intrinsic basicity, with the acetous pKb to aqueous pKb values being linearly related (slope 1.18, correlation coefficient 0.962). A minimum acetous delta pKb of four units is required for the satisfactory differential titration of two bases in acetic acid.

  19. Genetic dissection of acetic acid tolerance in Saccharomyces cerevisiae.

    PubMed

    Geng, Peng; Xiao, Yin; Hu, Yun; Sun, Haiye; Xue, Wei; Zhang, Liang; Shi, Gui-Yang

    2016-09-01

    Dissection of the hereditary architecture underlying Saccharomyces cerevisiae tolerance to acetic acid is essential for ethanol fermentation. In this work, a genomics approach was used to dissect hereditary variations in acetic acid tolerance between two phenotypically different strains. A total of 160 segregants derived from these two strains were obtained. Phenotypic analysis indicated that the acetic acid tolerance displayed a normal distribution in these segregants, and suggested that the acetic acid tolerant traits were controlled by multiple quantitative trait loci (QTLs). Thus, 220 SSR markers covering the whole genome were used to detect QTLs of acetic acid tolerant traits. As a result, three QTLs were located on chromosomes 9, 12, and 16, respectively, which explained 38.8-65.9 % of the range of phenotypic variation. Furthermore, twelve genes of the candidates fell into the three QTL regions by integrating the QTL analysis with candidates of acetic acid tolerant genes. These results provided a novel avenue to obtain more robust strains.

  20. Lactic acid production from xylose by engineered Saccharomyces cerevisiae without PDC or ADH deletion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Production of lactic acid from renewable sugars has received growing attention as lactic acid can be used for making renewable and bio-based plastics. However, most prior studies have focused on production of lactic acid from glucose despite cellulosic hydrolysates contain xylose as well as glucose....

  1. Lactic acid delays the inflammatory response of human monocytes

    SciTech Connect

    Peter, Katrin; Rehli, Michael; Singer, Katrin; Renner-Sattler, Kathrin; Kreutz, Marina

    2015-02-13

    Lactic acid (LA) accumulates under inflammatory conditions, e.g. in wounds or tumors, and influences local immune cell functions. We previously noted inhibitory effects of LA on glycolysis and TNF secretion of human LPS-stimulated monocytes. Here, we globally analyze the influence of LA on gene expression during monocyte activation. To separate LA-specific from lactate- or pH-effects, monocytes were treated for one or four hours with LPS in the presence of physiological concentrations of LA, sodium lactate (NaL) or acidic pH. Analyses of global gene expression profiles revealed striking effects of LA during the early stimulation phase. Up-regulation of most LPS-induced genes was significantly delayed in the presence of LA, while this inhibitory effect was attenuated in acidified samples and not detected after incubation with NaL. LA targets included genes encoding for important monocyte effector proteins like cytokines (e.g. TNF and IL-23) or chemokines (e.g. CCL2 and CCL7). LA effects were validated for several targets by quantitative RT-PCR and/or ELISA. Further analysis of LPS-signaling pathways revealed that LA delayed the phosphorylation of protein kinase B (AKT) as well as the degradation of IκBα. Consistently, the LPS-induced nuclear accumulation of NFκB was also diminished in response to LA. These results indicate that the broad effect of LA on gene expression and function of human monocytes is at least partially caused by its interference with immediate signal transduction events after activation. This mechanism might contribute to monocyte suppression in the tumor environment. - Highlights: • Lactic acid broadly delays LPS-induced gene expression in human monocytes. • Expression of important monocyte effector molecules is affected by lactic acid. • Interference of lactic acid with TLR signaling causes the delayed gene expression. • The profound effect of lactic acid might contribute to immune suppression in tumors.

  2. Effects of lactic acid bacteria contamination on lignocellulosic ethanol fermentation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Slower fermentation rates, mixed sugar compositions, and lower sugar concentrations may make lignocellulosic fermentations more susceptible to contamination by lactic acid bacteria (LAB), which is a common and costly problem to the corn-based fuel ethanol industry. To examine the effects of LAB con...

  3. Production of Value-added Products by Lactic Acid Bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lactic acid bacteria (LAB) are a group of facultative anaerobic, catalase negative, nonmotile and nonsporeforming–Gram positive bacteria. Most LAB utilize high energy C sources including monomer sugars to produce energy to maintain cellular structure and function. This anaerobic fermentation proce...

  4. Thermal properties of poly (lactic acid)/milkweed composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, most polymer composites utilize petroleum-based materials that are non-degradable and difficult to recycle or incur substantial cost for disposal. Green composites can be used in nondurable limited applications. In order to determine the degree of compatibility between Poly (lactic Acid...

  5. GAS PERMEATION PROPERTIES OF POLY(LACTIC ACID). (R826733)

    EPA Science Inventory

    Abstract

    The need for the development of polymeric materials based on renewable resources has led to the development of poly(lactic acid) (PLA) which is being produced from a feedstock of corn rather than petroleum. The present study examines the permeation of nitrogen...

  6. Poly(lactic acid) degradable plastics, coatings, and binders

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.; Mudde, J.P.

    1992-05-01

    Biochemical processes to derive value from the management of high carbohydrate food wastes, such as potato starch, corn starch, and cheese whey permeate, have typically been limited to the production of either ethanol or methane. Argonne National Laboratory (ANL) believes that lactic acid presents an attractive option for an alternate fermentation end product, especially in light of lactic acids` being a viable candidate for conversion to environmentally safe poly(lactic acid) (PLA) degradable plastics, coatings, and binders. Technology is being developed at ANL to permit a more cost effective route to modified high molecular weight PLA. Preliminary data on the degradation behavior of these modified PLAs shows the retention to the inherent hydrolytic degradability of the PLA modified, however, by introduced compositional variables. A limited study was done on the hydrolytic stability of soluble oligomers of poly(L-lactic acid). Over a 34 day hold period, water-methanol solutions of Pl-LA oligomers in the 2-10 DP range retained some 75% of their original molecular weight.

  7. Poly(lactic acid) degradable plastics, coatings, and binders

    SciTech Connect

    Bonsignore, P.V.; Coleman, R.D.; Mudde, J.P.

    1992-01-01

    Biochemical processes to derive value from the management of high carbohydrate food wastes, such as potato starch, corn starch, and cheese whey permeate, have typically been limited to the production of either ethanol or methane. Argonne National Laboratory (ANL) believes that lactic acid presents an attractive option for an alternate fermentation end product, especially in light of lactic acids' being a viable candidate for conversion to environmentally safe poly(lactic acid) (PLA) degradable plastics, coatings, and binders. Technology is being developed at ANL to permit a more cost effective route to modified high molecular weight PLA. Preliminary data on the degradation behavior of these modified PLAs shows the retention to the inherent hydrolytic degradability of the PLA modified, however, by introduced compositional variables. A limited study was done on the hydrolytic stability of soluble oligomers of poly(L-lactic acid). Over a 34 day hold period, water-methanol solutions of Pl-LA oligomers in the 2-10 DP range retained some 75% of their original molecular weight.

  8. Systems solutions by lactic acid bacteria: from paradigms to practice

    PubMed Central

    2011-01-01

    Lactic acid bacteria are among the powerhouses of the food industry, colonize the surfaces of plants and animals, and contribute to our health and well-being. The genomic characterization of LAB has rocketed and presently over 100 complete or nearly complete genomes are available, many of which serve as scientific paradigms. Moreover, functional and comparative metagenomic studies are taking off and provide a wealth of insight in the activity of lactic acid bacteria used in a variety of applications, ranging from starters in complex fermentations to their marketing as probiotics. In this new era of high throughput analysis, biology has become big science. Hence, there is a need to systematically store the generated information, apply this in an intelligent way, and provide modalities for constructing self-learning systems that can be used for future improvements. This review addresses these systems solutions with a state of the art overview of the present paradigms that relate to the use of lactic acid bacteria in industrial applications. Moreover, an outlook is presented of the future developments that include the transition into practice as well as the use of lactic acid bacteria in synthetic biology and other next generation applications. PMID:21995776

  9. Use of Gas-Liquid Chromatography to Determine the End Products of Growth of Lactic Acid Bacteria

    PubMed Central

    Thornhill, Patrick J.; Cogan, Timothy M.

    1984-01-01

    A simple gas-liquid chromatographic procedure for analyzing ethanol, acetic acid, acetoin, and racemic and meso-2,3-butylene glycol in broth media is described. Overnight broth cultures were filtered or centrifuged, and the filtrate or supernatant was treated with formic acid to aid separation of volatile fatty acids. Samples were then directly analyzed by gas-liquid chromatography on a 20% Tween 80-Chromosorb W-AW column and propionic acid as an internal standard. A complete analysis took ca. 8 min. The method can be used to distinguish homofermentative from heterofermentative lactic acid bacteria based on the level of ethanol produced and citrate-utilizing from non-citrate-utilizing lactic acid bacteria based on the levels of acetic acid produced. The method also has potential in distinguishing other bacterial fermentations. Of the 13 species of lactic acid bacteria tested, Streptococcus lactis subsp. diacetylactis was the major producer of 2,3-butylene glycol (total range, 0.3 to 3.5 mM), and, except for strain DRC1, both the racemic and meso isomers were produced in approximately equal amounts. PMID:16346562

  10. [Metabolic engineering of wild acid-resistant yeast for L-lactic acid production].

    PubMed

    Zhang, Qin; Zhang, Liang; Ding, Zhongyang; Wang, Zhengxiang; Shi, Guiyang

    2011-07-01

    In order to obtain a yeast strain able to produce L-lactic acid under the condition of low pH and high lactate content, one wild acid-resistant yeast strain isolated from natural samples, was found to be able to grow well in YEPD medium (20 g/L glucose, 20 g/L tryptone, 10 g/L yeast extract, adjusted pH 2.5 with lactic acid) without consuming lactic acid. Based on further molecular biological tests, the strain was identified as Candida magnolia. Then, the gene ldhA, encoding a lactate dehydrogenase from Rhizopus oryzae, was cloned into a yeast shuttle vector containing G418 resistance gene. The resultant plasmid pYX212-kanMX-ldhA was introduced into C. magnolia by electroporation method. Subsequently, a recombinant L-lactic acid producing yeast C. magnolia-2 was obtained. The optimum pH of the recombinant yeast is 3.5 for lactic acid production. Moreover, the recombinant strain could grow well and produce lactic acid at pH 2.5. This recombinant yeast strain could be useful for producing L-lactic acid.

  11. Isolation and characterisation of lactic acid bacterium for effective fermentation of cellobiose into optically pure homo L-(+)-lactic acid.

    PubMed

    Abdel-Rahman, Mohamed Ali; Tashiro, Yukihiro; Zendo, Takeshi; Shibata, Keisuke; Sonomoto, Kenji

    2011-02-01

    Effective utilisation of cellulosic biomasses for economical lactic acid production requires a microorganism with potential ability to utilise efficiently its major components, glucose and cellobiose. Amongst 631 strains isolated from different environmental samples, strain QU 25 produced high yields of l-(+)-lactic acid of high optical purity from cellobiose. The QU 25 strain was identified as Enterococcus mundtii based on its sugar fermentation pattern and 16S rDNA sequence. The production of lactate by fermentation was optimised for the E. mundtii QU25 strain. The optimal pH and temperature for batch culturing were found to be 7.0°C and 43°C, respectively. E. mundtii QU 25 was able to metabolise a mixture of glucose and cellobiose simultaneously without apparent carbon catabolite repression. Moreover, under the optimised culture conditions, production of optically pure l-lactic acid (99.9%) increased with increasing cellobiose concentrations. This indicates that E. mundtii QU 25 is a potential candidate for effective lactic acid production from cellulosic hydrolysate materials.

  12. Influence of sodium chloride, pH, and lactic acid bacteria on anaerobic lactic acid utilization during fermented cucumber spoilage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucumbers are preserved commercially by natural fermentations in 5% to 8% sodium chloride (NaCl) brines. Occasionally, fermented cucumbers spoil after the primary fermentation is complete. This spoilage has been characterized by decreases in lactic acid and a rise in brine pH caused by microbial ins...

  13. Growth and Metabolism of Lactic Acid Bacteria during and after Malolactic Fermentation of Wines at Different pH

    PubMed Central

    Davis, C. R.; Wibowo, D. J.; Lee, T. H.; Fleet, G. H.

    1986-01-01

    Commercially produced red wines were adjusted to pH 3.0, 3.2, 3.5, 3.7, or 4.0 and examined during and after malolactic fermentation for growth of lactic acid bacteria and changes in the concentrations of carbohydrates, organic acids, amino acids, and acetaldehyde. With one exception, Leuconostoc oenos conducted the malolactic fermentation in all wines and was the only species to occur in wines at pH below 3.5. Malolactic fermentation by L. oenos was accompanied by degradation of malic, citric, and fumaric acids and production of lactic and acetic acids. The concentrations of arginine, histidine, and acetaldehyde also decreased at this stage, but the behavior of hexose and pentose sugars was complicated by other factors. Pediococcus parvulus conducted the malolactic fermentation in one wine containing 72 mg of total sulfur dioxide per liter. Fumaric and citric acids were not degraded during this malolactic fermentation, but hexose sugars were metabolized. P. parvulus and species of Lactobacillus grew after malolactic fermentation in wines with pH adjusted above 3.5. This growth was accompanied by the utilization of wine sugars and production of lactic and acetic acids. PMID:16347015

  14. Oxidation of indole-3-acetic acid to oxindole-3-acetic acid by an enzyme preparation from Zea mays

    NASA Technical Reports Server (NTRS)

    Reinecke, D. M.; Bandurski, R. S.

    1988-01-01

    Indole-3-acetic acid is oxidized to oxindole-3-acetic acid by Zea mays tissue extracts. Shoot, root, and endosperm tissues have enzyme activities of 1 to 10 picomoles per hour per milligram protein. The enzyme is heat labile, is soluble, and requires oxygen for activity. Cofactors of mixed function oxygenase, peroxidase, and intermolecular dioxygenase are not stimulatory to enzymic activity. A heat-stable, detergent-extractable component from corn enhances enzyme activity 6- to 10-fold. This is the first demonstration of the in vitro enzymic oxidation of indole-3-acetic acid to oxindole-3-acetic acid in higher plants.

  15. Viscometric study of chitosan solutions in acetic acid/sodium acetate and acetic acid/sodium chloride.

    PubMed

    Costa, Cristiane N; Teixeira, Viviane G; Delpech, Marcia C; Souza, Josefa Virginia S; Costa, Marcos A S

    2015-11-20

    A viscometric study was carried out at 25°C to assess the physical-chemical behavior in solution and the mean viscometric molar mass (M¯v) of chitosan solutions with different deacetylation degrees, in two solvent mixtures: medium 1-acetic acid 0.3mol/L and sodium acetate 0.2mol/L; and medium 2-acetic acid 0.1mol/L and sodium chloride 0.2mol/L. Different equations were employed, by graphical extrapolation, to calculate the intrinsic viscosities [η] and the viscometric constants, to reveal the solvent's quality: Huggins (H), Kraemer (K) and Schulz-Blaschke (SB). For single-point determination, the equations used were SB, Solomon-Ciuta (SC) and Deb-Chanterjee (DC), resulting in a faster form of analysis. The values of ̄M¯v were calculated by applying the equation of Mark-Houwink-Sakurada. The SB and SC equations were most suitable for single-point determination of [η] and ̄M¯v and the Schulz-Blachke constant (kSB), equal to 0.28, already utilized for various systems, can also be employed to analyze chitosan solutions under the conditions studied.

  16. Recovery of acetic acid from waste streams by extractive distillation.

    PubMed

    Demiral, H; Yildirim, M Ercengiz

    2003-01-01

    Wastes have been considered to be a serious worldwide environmental problem in recent years. Because of increasing pollution, these wastes should be treated. However, industrial wastes can contain a number of valuable organic components. Recovery of these components is important economically. Using conventional distillation techniques, the separation of acetic acid and water is both impractical and uneconomical, because it often requires large number of trays and a high reflux ratio. In practice special techniques are used depending on the concentration of acetic acid. Between 30 and 70% (w/w) acetic acid contents, extractive distillation was suggested. Extractive distillation is a multicomponent-rectification method similar in purpose to azeotropic distillation. In extractive distillation, to a binary mixture which is difficult or impossible to separate by ordinary means, a third component termed an entrainer is added which alters the relative volatility of the original constituents, thus permitting the separation. In our department acetic acid is used as a solvent during the obtaining of cobalt(III) acetate from cobalt(II) acetate by an electrochemical method. After the operation, the remaining waste contains acetic acid. In thiswork, acetic acid which has been found in this waste was recovered by extractive distillation. Adiponitrile and sulfolane were used as high boiling solvents and the effects of solvent feed rate/solution feed rate ratio and type were investigated. According to the experimental results, it was seem that the recovery of acetic acid from waste streams is possible by extractive distillation.

  17. The thermodynamic properties of S-lactic acid

    NASA Astrophysics Data System (ADS)

    Emel'Yanenko, V. N.; Verevkin, S. P.; Schick, C.; Stepurko, E. N.; Roganov, G. N.; Georgieva, M. K.

    2010-09-01

    The enthalpies of combustion and formation of S-lactic acid at 298.15 K, Δc H {m/o}(cr.) = -1337.9 ± 0.8 and Δf H {m/o}(cr.) = -700.1 ± 0.9 kJ/mol, were determined by calorimetry. The temperature dependence of acid vapor pressure was studied by the transpiration method, and the enthalpy of its vaporization was obtained, Δvap H o(298.15 K) = 69.1 ± 1.0 kJ/mol. The temperature and enthalpy of fusion, T m (330.4 K) and Δm H o(298.15 K) = 14.7 ± 0.2 kJ/mol, were determined by differential scanning calorimetry. The enthalpy of formation of the acid in the gas phase was obtained. Ab initio methods were used to perform a conformational analysis of the acid, calculate fundamental vibration frequencies, moments of inertia, and total and relative energies of the stablest conformers. Thermodynamic properties were calculated in the ideal gas state over the temperature range 0-1500 K. A thermodynamic analysis of mutual transformation processes (the formation of SS- and RS(meso)-lactides from S-lactic acid and the racemization of these lactides) and the formation of poly-(RS)-lactide from S-lactic acid and SS- and RS(meso)-lactides was performed.

  18. Micelles Protect and Concentrate Activated Acetic Acid

    NASA Astrophysics Data System (ADS)

    Todd, Zoe; House, C.

    2014-01-01

    As more and more exoplanets are discovered and the habitability of such planets is considered, one can turn to searching for the origin of life on Earth in order to better understand what makes a habitable planet. Activated acetic acid, or methyl thioacetate, has been proposed to be central to the origin of life on Earth, and also as an important energy currency molecule in early cellular evolution. We have investigated the hydrolysis of methyl thioacetate under various conditions. Its uncatalyzed rate of hydrolysis is about three orders of magnitude faster (K = 0.00663 s^-1; 100°C, pH 7.5, concentration = 0.33mM) than published rates for its catalyzed production making it unlikely to accumulate under prebiotic conditions. However, we also observed that methyl thioacetate was protected from hydrolysis when inside its own hydrophobic droplets. We found that methyl thioacetate protection from hydrolysis was also possible in droplets of hexane and in the membranes of nonanoic acid micelles. Thus, the hydrophobic regions of prebiotic micelles and early cell membranes could have offered a refuge for this energetic molecule increasing its lifetime in close proximity to the reactions for which it would be needed. Methyl thioacetate could thus be important for the origin of life on Earth and perhaps for better understanding the potential habitability of other planets.

  19. Mechanism of L-lactic acid transport in L6 skeletal muscle cells.

    PubMed

    Kobayashi, Masaki; Itagaki, Shirou; Hirano, Takeshi; Iseki, Ken

    2004-10-01

    L-lactic acid transport plays an important role in the regulation of L-lactic acid circulation into and out of muscle. To clarify the transport mechanism of L-lactic acid in skeletal muscle, L-lactic acid uptake was investigated using a L6 cell line. mRNAs of monocarboxylate transporter (MCT) 1, 2 and 4 were found to be expressed in L6 cells. The [(14)C] L-lactic acid uptake by L6 cells increased up to pH of 6.0. The [(14)C] L-lactic acid uptake at pH 6.0 was concentration-dependent with a K(m) of 3.7 mM. This process was reduced by alpha-cyano-4-hydroxycinnamate, a typical MCT1, 2 and 4 inhibitor. These results suggest that an MCT participates in the uptake of L-lactic acid by L6 cells. [(14)C] L-lactic acid uptake was markedly inhibited by monocarboxylic acids and monocarboxylate drugs but not by dicarboxylic acids and amino acids. Moreover, benzoic acid, a substrate for MCT1, competitively inhibited this process with K(i) of 1.7 mM. [(14)C] L-lactic acid efflux in L6 cells was inhibited by alpha-cyano-4-hydroxycinnamate but not by benzoic acid. These results suggest that [(14)C] L-lactic acid efflux in L6 cells is mediated by MCT other than MCT1.

  20. Effect of monolaurin and lactic acid on Listeria monocytogenes attached to catfish fillets.

    PubMed

    Verhaegh, E G; Marshall, D L; Oh, D H

    1996-04-01

    The purpose of this study was to determine the effects of monolaurin and lactic acid, singly or combined, on Listeria monocytogenes attached to catfish fillets. Skinless catfish fillets were inoculated with L. monocytogenes and dip treated in monolaurin and/or lactic acid solution for various time periods. Results showed that monolaurin up to 400 micrograms/ml had no influence on counts. Conversely, lactic acid-treated fillets had reduced counts compared to controls. Dipping in 0.85, 1.70, or 2.55% lactic acid for 30 min reduced counts by 0.9, 1.4, or 1.3 logs, respectively. Extending the dipping time to 60 min resulted in little additional decrease in counts. Combining monolaurin with lactic acid yielded results similar to lactic acid alone. Hence, population reduction ability resides with lactic acid and not monolaurin.

  1. pH-Uncontrolled lactic acid fermentation with activated carbon as an adsorbent.

    PubMed

    Gao, Min-Tian; Shimamura, Takashi; Ishida, Nobuhiro; Takahashi, Haruo

    2011-05-06

    In this paper, we presented a novel process involving activated carbon (AC) as an adsorbent for lactic acid fermentation, separation and oligomerization. It was found that pH has a significant effect on the adsorption of lactic acid on AC. The use of AC for in situ removal of lactic acid successfully decreased the inhibitory effect of lactic acid, resulting in significant increases in both productivity and yield. Acetone was used to desorb lactic acid and it was confirmed that the acetone treatment did not decrease the optical purity of the lactic acid, i.e., the optical purity was as high as 99.5% after desorption. Due to the presence of little materials influencing lactic acid oligomerization, oligomers with an optical purity of above 96% and a weight-average molecular weight (M(w)) of 2400 were obtained in the oligomerization process.

  2. Biological Function of Acetic Acid-Improvement in Obesity and Glucose Tolerance by Acetic Acid in Type 2 Diabetic Rats.

    PubMed

    Yamashita, Hiromi

    2016-07-29

    Fatty acids derived from adipose tissue are oxidized by β-oxidation to form ketone bodies as final products under the starving condition. Previously, we found that free acetic acid was formed concomitantly with the production of ketone bodies in isolated rat liver perfusion, and mitochondrial acetyl CoA hydrolase was appeared to be involved with the acetic acid production. It was revealed that acetic acid was formed as a final product of enhanced β-oxidation of fatty acids and utilized as a fuel in extrahepatic tissues under the starving condition. Under the fed condition, β-oxidation is suppressed and acetic acid production is decreased. When acetic acid was taken daily by obesity-linked type 2 diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats under the fed condition, it protected OLETF rats against obesity. Furthermore, acetic acid contributed to protect from the accumulation of lipid in the liver as well as abdominal fat in OLETF rats. Transcripts of lipogenic genes in the liver were decreased, while transcripts of myoglobin and Glut4 genes in abdominal muscles were increased in the acetic acid-administered OLETF rats. It is indicated that exogenously administered acetic acid would have effects on lipid metabolism in both the liver and the skeletal muscles, and have function that works against obesity and obesity-linked type 2 diabetes.

  3. Trehalose accumulation enhances tolerance of Saccharomyces cerevisiae to acetic acid.

    PubMed

    Yoshiyama, Yoko; Tanaka, Koichi; Yoshiyama, Kohei; Hibi, Makoto; Ogawa, Jun; Shima, Jun

    2015-02-01

    Trehalose confers protection against various environmental stresses on yeast cells. In this study, trehalase gene deletion mutants that accumulate trehalose at high levels showed significant stress tolerance to acetic acid. The enhancement of trehalose accumulation can thus be considered a target in the breeding of acetic acid-tolerant yeast strains.

  4. Stereocomplexes of enantiomeric lactic acid and sebacic acid ester-anhydride triblock copolymers.

    PubMed

    Slivniak, Raia; Domb, Abraham J

    2002-01-01

    A systematic study on the synthesis, characterization, degradation, and drug release of d-, l-, and dl-poly(lactic acid) (PLA)-terminated poly(sebacic acid) (PSA) and their stereocomplexes is reported. PLA-terminated sebacic acid polymers were synthesized by melt condensation of the acetate anhydride derivatives of PLA oligomers and sebacic anhydride oligomers to yield ABA triblock copolymers of molecular weights between 3000 and 9000 that melt at temperatures between 35 and 80 degrees C. Pairs of the corresponding enantiomeric ABA copolymers composed of l-PLA-PSA-l-PLA and d-PLA-PSA-d-PLA were solvent mixed to form stereocomplexes. The formed stereocomplexes exhibited higher crystalline melting temperature than the enantiomeric polymers, which indicate stereocomplex formulation. The PLA terminals had a significant effect on the polymer degradation and drug release rate. PSA with up to 20% w/w of PLA terminals degraded and released the incorporated drug for more than 3 weeks as compared with 10 days for PSA homopolymer.

  5. Lactic acid production from xylose by engineered Saccharomyces cerevisiae without PDC or ADH deletion.

    PubMed

    Turner, Timothy L; Zhang, Guo-Chang; Kim, Soo Rin; Subramaniam, Vijay; Steffen, David; Skory, Christopher D; Jang, Ji Yeon; Yu, Byung Jo; Jin, Yong-Su

    2015-10-01

    Production of lactic acid from renewable sugars has received growing attention as lactic acid can be used for making renewable and bio-based plastics. However, most prior studies have focused on production of lactic acid from glucose despite that cellulosic hydrolysates contain xylose as well as glucose. Microbial strains capable of fermenting both glucose and xylose into lactic acid are needed for sustainable and economic lactic acid production. In this study, we introduced a lactic acid-producing pathway into an engineered Saccharomyces cerevisiae capable of fermenting xylose. Specifically, ldhA from the fungi Rhizopus oryzae was overexpressed under the control of the PGK1 promoter through integration of the expression cassette in the chromosome. The resulting strain exhibited a high lactate dehydrogenase activity and produced lactic acid from glucose or xylose. Interestingly, we observed that the engineered strain exhibited substrate-dependent product formation. When the engineered yeast was cultured on glucose, the major fermentation product was ethanol while lactic acid was a minor product. In contrast, the engineered yeast produced lactic acid almost exclusively when cultured on xylose under oxygen-limited conditions. The yields of ethanol and lactic acid from glucose were 0.31 g ethanol/g glucose and 0.22 g lactic acid/g glucose, respectively. On xylose, the yields of ethanol and lactic acid were <0.01 g ethanol/g xylose and 0.69 g lactic acid/g xylose, respectively. These results demonstrate that lactic acid can be produced from xylose with a high yield by S. cerevisiae without deleting pyruvate decarboxylase, and the formation patterns of fermentations can be altered by substrates.

  6. Fermentation of lignocellulosic sugars to acetic acid by Moorella thermoacetica.

    PubMed

    Ehsanipour, Mandana; Suko, Azra Vajzovic; Bura, Renata

    2016-06-01

    A systematic study of bioconversion of lignocellulosic sugars to acetic acid by Moorella thermoacetica (strain ATCC 39073) was conducted. Four different water-soluble fractions (hydrolysates) obtained after steam pretreatment of lignocellulosic biomass were selected and fermented to acetic acid in batch fermentations. M. thermoacetica can effectively ferment xylose and glucose in hydrolysates from wheat straw, forest residues, switchgrass, and sugarcane straw to acetic acid. Xylose and glucose were completely utilized, with xylose being consumed first. M. thermoacetica consumed up to 62 % of arabinose, 49 % galactose and 66 % of mannose within 72 h of fermentation in the mixture of lignocellulosic sugars. The highest acetic acid yield was obtained from sugarcane straw hydrolysate, with 71 % of theoretical yield based on total sugars (17 g/L acetic acid from 24 g/L total sugars). The lowest acetic acid yield was observed in forest residues hydrolysate, with 39 % of theoretical yield based on total sugars (18 g/L acetic acid from 49 g/L total sugars). Process derived compounds from steam explosion pretreatment, including 5-hydroxymethylfurfural (0.4 g/L), furfural (0.1 g/L) and total phenolics (3 g/L), did not inhibit microbial growth and acetic acid production yield. This research identified two major factors that adversely affected acetic acid yield in all hydrolysates, especially in forest residues: (i) glucose to xylose ratio and (ii) incomplete consumption of arabinose, galactose and mannose. For efficient bioconversion of lignocellulosic sugars to acetic acid, it is imperative to have an appropriate balance of sugars in a hydrolysate. Hence, the choice of lignocellulosic biomass and steam pretreatment design are fundamental steps for the industrial application of this process.

  7. Enhanced Osteoblast Functions on Nanophase Titania in Poly-lactic-co-glycolic Acid (PLGA) Composites

    DTIC Science & Technology

    2005-01-01

    Poly - lactic -co-glycolic Acid (PLGA) Composites Huinan Liu’, Elliott B. Slamovich’ and Thomas J. Webster’ 2 1School of Materials Engineering, 501...collagen matrix. For this purpose, poly - lactic -co- glycolic acid (PLGA) was dissolved in chloroform and nanometer grain size titania was dispersed by...gelatin, fibrin or collagen [4-6]), synthetic bioresorbable polymers (e.g., polylactic acid , polyglycolic acid and poly - lactic -co-glycolic acid [7-9

  8. Accelerated fatigue of dentin with exposure to lactic acid.

    PubMed

    Do, Dominic; Orrego, Santiago; Majd, Hessam; Ryou, Heonjune; Mutluay, Mustafa M; Xu, Hockin H K; Arola, Dwayne D

    2013-11-01

    Composite restorations accumulate more biofilm than other dental materials. This increases the likelihood for the hard tissues supporting a restoration (i.e. dentin and enamel) to be exposed to acidic conditions beyond that resulting from dietary variations. In this investigation the fatigue strength and fatigue crack growth resistance of human coronal dentin were characterized within a lactic acid solution (with pH = 5) and compared to that of controls evaluated in neutral conditions (pH = 7). A comparison of the fatigue life distributions showed that the lactic acid exposure resulted in a significant reduction in the fatigue strength (p ≤ 0.001), and nearly 30% reduction in the apparent endurance limit (from 44 MPa to 32 MPa). The reduction in pH also caused a significant decrease (p ≤ 0.05) in the threshold stress intensity range required for the initiation of cyclic crack growth, and significant increase in the incremental rate of crack extension. Exposure of tooth structure to lactic acid may cause demineralization, but it also increases the likelihood of restored tooth failures via fatigue, and after short time periods.

  9. Measurement of the rates of oxindole-3-acetic acid turnover, and indole-3-acetic acid oxidation in Zea mays seedlings

    NASA Technical Reports Server (NTRS)

    Nonhebel, H. M.; Bandurski, R. S. (Principal Investigator)

    1986-01-01

    Oxindole-3-acetic acid is the principal catabolite of indole-3-acetic acid in Zea mays seedlings. In this paper measurements of the turnover of oxindole-3-acetic acid are presented and used to calculate the rate of indole-3-acetic acid oxidation. [3H]Oxindole-3-acetic acid was applied to the endosperm of Zea mays seedlings and allowed to equilibrate for 24 h before the start of the experiment. The subsequent decrease in its specific activity was used to calculate the turnover rate. The average half-life of oxindole-3-acetic acid in the shoots was found to be 30 h while that in the kernels had an average half-life of 35h. Using previously published values of the pool sizes of oxindole-3-acetic acid in shoots and kernels from seedlings of the same age and variety, and grown under the same conditions, the rate of indole-3-acetic acid oxidation was calculated to be 1.1 pmol plant-1 h-1 in the shoots and 7.1 pmol plant-1 h-1 in the kernels.

  10. Lactic acid fermentation by cells immobilised on various porous cellulosic materials and their alginate/poly-lactic acid composites.

    PubMed

    Kumar, Mrinal Nishant; Gialleli, Angelika-Ioanna; Masson, Jean Bernard; Kandylis, Panagiotis; Bekatorou, Argyro; Koutinas, Athanasios A; Kanellaki, Maria

    2014-08-01

    Porous delignified cellulose (or tubular cellulose, abbr. TC) from Indian Mango (Mangifera indica) and Sal (Shorea robusta) wood and Rice husk, and TC/Ca-alginate/polylactic acid composites, were used as Lactobacillus bulgaricus immobilisation carriers leading to improvements in lactic acid fermentation of cheese whey and synthetic lactose media, compared to free cells. Specifically, shorter fermentation rates, higher lactic acid yields (g/g sugar utilised) and productivities (g/Ld), and higher amounts of volatile by-products were achieved, while no significant differences were observed on the performance of the different immobilised biocatalysts. The proposed biocatalysts are of food grade purity, cheap and easy to prepare, and they are attractive for bioprocess development based on immobilised cells. Such composite biocatalysts may be used for the co-immobilisation of different microorganisms or enzymes (in separate layers of the biocatalyst), to efficiently conduct different types of fermentations in the same bioreactor, avoiding inhibition problems of chemical or biological (competition) nature.

  11. Bacteriocins of lactic acid bacteria: extending the family.

    PubMed

    Alvarez-Sieiro, Patricia; Montalbán-López, Manuel; Mu, Dongdong; Kuipers, Oscar P

    2016-04-01

    Lactic acid bacteria (LAB) constitute a heterogeneous group of microorganisms that produce lactic acid as the major product during the fermentation process. LAB are Gram-positive bacteria with great biotechnological potential in the food industry. They can produce bacteriocins, which are proteinaceous antimicrobial molecules with a diverse genetic origin, posttranslationally modified or not, that can help the producer organism to outcompete other bacterial species. In this review, we focus on the various types of bacteriocins that can be found in LAB and the organization and regulation of the gene clusters responsible for their production and biosynthesis, and consider the food applications of the prototype bacteriocins from LAB. Furthermore, we propose a revised classification of bacteriocins that can accommodate the increasing number of classes reported over the last years.

  12. Lactic acid fermentation in cell-recycle membrane bioreactor.

    PubMed

    Choudhury, B; Swaminathan, T

    2006-02-01

    Traditional lactic acid fermentation suffers from low productivity and low product purity. Cell-recycle fermentation has become one of the methods to obtain high cell density, which results in higher productivity. Lactic acid fermentation was investigated in a cell-recycle membrane bioreactor at higher substrate concentrations of 100 and 120 g/dm3. A maximum cell density of 145 g/dm3 and a maximum productivity of 34 g/(dm3.h) were achieved in cell-recycle fermentation. In spite of complete consumption of substrate, there was a continuous increase in cell density in cell-recycle fermentation. Control of cell density in cell-recycle fermentation was attempted by cell bleeding and reduction in yeast extract concentration.

  13. Oxidation of indole-3-acetic acid and oxindole-3-acetic acid to 2,3-dihydro-7-hydroxy-2-oxo-1H indole-3-acetic acid-7'-O-beta-D-glucopyranoside in Zea mays seedlings

    NASA Technical Reports Server (NTRS)

    Nonhebel, H. M.; Bandurski, R. S.

    1984-01-01

    Radiolabeled oxindole-3-acetic acid was metabolized by roots, shoots, and caryopses of dark grown Zea mays seedlings to 2,3-dihydro-7-hydroxy-2-oxo-1H indole-3-acetic acid-7'-O-beta-D-glycopyranoside with the simpler name of 7-hydroxyoxindole-3-acetic acid-glucoside. This compound was also formed from labeled indole-3-acetic acid supplied to intact seedlings and root segments. The glucoside of 7-hydroxyoxindole-3-acetic acid was also isolated as an endogenous compound in the caryopses and shoots of 4-day-old seedlings. It accumulates to a level of 4.8 nanomoles per plant in the kernel, more than 10 times the amount of oxindole-3-acetic acid. In the shoot it is present at levels comparable to that of oxindole-3-acetic acid and indole-3-acetic acid (62 picomoles per shoot). We conclude that 7-hydroxyoxindole-3-acetic acid-glucoside is a natural metabolite of indole-3-acetic acid in Z. mays seedlings. From the data presented in this paper and in previous work, we propose the following route as the principal catabolic pathway for indole-3-acetic acid in Zea seedlings: Indole-3-acetic acid --> Oxindole-3-acetic acid --> 7-Hydroxyoxindole-3-acetic acid --> 7-Hydroxyoxindole-3-acetic acid-glucoside.

  14. RECOVERY OF LACTIC ACID FROM AMERICAN CRYSTAL SUGAR COMPANY WASTEWATER

    SciTech Connect

    Daniel J. Stepan; Edwin S. Olson; Richard E. Shockey; Bradley G. Stevens; John R. Gallagher

    2001-04-30

    This project has shown that the recovery of several valuable lactic acid products is both technically feasible and economically viable. One of the original objectives of this project was to recover lactic acid. However, the presence of a variety of indigenous bacteria in the wastewater stream and technical issues related to recovery and purification have resulted in the production of lactic acid esters. These esters could by hydrolyzed to lactic acid, but only with unacceptable product losses that would be economically prohibitive. The developed process is projected to produce approximately 200,000 lb per day of lactate esters from wastewater at a single factory at costs that compete with conventional solvents. The lactate esters are good solvents for polymers and resins and could replace acetone, methyl ethyl ketone, MIBK, and other polar solvents used in the polymer industry. Because of their low volatility and viscosity-lowering properties, they will be especially useful for inks for jet printers, alkyl resins, and high-solid paints. Owing to their efficiency in dissolving salts and flux as well as oils and sealants, lactate esters can be used in cleaning circuit boards and machine and engine parts. Unlike conventional solvents, lactate esters exhibit low toxicity, are biodegradable, and are not hazardous air pollutants. Another application for lactate esters is in the production of plasticizers. Severe health problems have been attributed to widely used phthalate ester plasticizers. The U.S. Department of Agriculture showed that replacement of these with inexpensive lactate esters is feasible, owing to their superior polymer compatibility properties. A very large market is projected for polymers prepared from lactic acid. These are called polylactides and are a type of polyester. Thermoplastics of this type have a variety of uses, including moldings, fibers, films, and packaging of both manufactured goods and food products. Polylactides form tough, orientable

  15. Complete genome sequence of Lactococcus lactis IO-1, a lactic acid bacterium that utilizes xylose and produces high levels of L-lactic acid.

    PubMed

    Kato, Hiroaki; Shiwa, Yuh; Oshima, Kenshiro; Machii, Miki; Araya-Kojima, Tomoko; Zendo, Takeshi; Shimizu-Kadota, Mariko; Hattori, Masahira; Sonomoto, Kenji; Yoshikawa, Hirofumi

    2012-04-01

    We report the complete genome sequence of Lactococcus lactis IO-1 (= JCM7638). It is a nondairy lactic acid bacterium, produces nisin Z, ferments xylose, and produces predominantly L-lactic acid at high xylose concentrations. From ortholog analysis with other five L. lactis strains, IO-1 was identified as L. lactis subsp. lactis.

  16. Lactic acid microflora of the gut of snail Cornu aspersum

    PubMed Central

    Koleva, Zdravka; Dedov, Ivaylo; Kizheva, Joana; Lipovanska, Roxana; Moncheva, Penka; Hristova, Petya

    2014-01-01

    The intestinal lactic acid microflora of the edible snail Cornu aspersum was studied by culture-based methods and was phenotypically and molecularly characterized. The antibacterial activity of lactic acid bacteria (LAB) isolates was investigated. Snails in different stages of development were collected from farms located in several regions of Bulgaria. One hundred twenty-two isolates, belonging to the group of LAB, were characterized morphologically and were divided into four groups. Representative isolates from each morphological type were subjected to phenotypic characterization and molecular identification. The snail gut lactic acid microflora was composed by Enterococcus (17 isolates), Lactococcus (12 isolates), Leuconostoc (7 isolates), Lactobacillus (18 isolates) and Weissella (1 isolate). The species affiliation of Lactococcus lactis (12), Leuconostoc mesenteroides (4) and Lactobacillus plantarum (2) was confirmed by species-specific primers. The Lactobacillus isolates were identified by sequence analysis of 16S rDNA as Lactobacillus brevis (12), L. plantarum (2), Lactobacillus graminis (1) and Lactobacillus curvatus (3). The species L. brevis, L. graminis and L. curvatus were found in snails in a phase of hibernation, whereas L. plantarum was identified both in active and hibernation phases. Antibacterial activity (bacteriocine-like) was shown only by one strain of L. mesentereoides P4/8 against Propionibacterium acnes. The present study showed that the LAB are a component of the microbial communities in the snail digestive system. This is the first report on Lactobacillus strains detected in the gut of C. aspersum. PMID:26019550

  17. Bioconversion of renewable resources into lactic acid: an industrial view.

    PubMed

    Yadav, A K; Chaudhari, A B; Kothari, R M

    2011-03-01

    Lactic acid, an anaerobic product of glycolysis, can be theoretically produced by synthetic route; however, it is commercially produced by homo-fermentative batch mode of operations. Factors affecting its production and strategies improving it are considered while devising an optimized protocol. Although a hetero-fermentative mode of production exists, it is rarely used for commercial production. Attempts to use Rhizopus sp. for lactic acid production through either hetero-fermentative or thermophilic conditions were not economical. Since almost 70% of the cost of its production is accounted by raw materials, R & D efforts are still focused to find economically attractive agri-products to serve as sources of carbon and complex nitrogen inputs to meet fastidious nutrient needs for microbial growth and lactic acid production. Therefore, need exists for using multi-pronged strategies for higher productivity. Its present production and consumption scenario is examined. Its optically active isomers and chemical structure permit its use for the production of several industrially important chemicals, health products (probiotics), food preservatives, and bio-plastics. In addition, its salts and esters appear to have a variety of applications.

  18. Effect of 82% Lactic Acid in Treatment of Melasma

    PubMed Central

    Singh, Rashmi; Goyal, Sapna; Ahmed, Qazi Rais; Gupta, Narendra; Singh, Sujata

    2014-01-01

    Melasma is an acquired, chronic, and symmetrical hypermelanosis, characterized by brown patches of variable darkness on sun exposed areas of body. There are numerous modalities of treatment currently in use for this disease, of which the chemical peeling is very commonly used. Therefore, the present work was done to see the effect of 82% lactic acid peel in the treatment of melasma. A total number of 20 patients of either sex attending the OPD of dermatology department with clinically evident melasma were included in the study. 82% Lactic acid peel was applied on the face for 12 weeks in each patient. Patients were evaluated clinically and photographically at various intervals and in follow-up till 24 weeks. Assessment of patient satisfaction and side effects were also noted. All the subjects completed the study. Application of this peel for 12 weeks significantly decreased the melasma area severity index score and also melasma severity scale score. Patient and physician analogue scales also showed the improvement by the treatment. Regarding the adverse effects, burning sensation was the only side effect noted in our study. In conclusion, 82% lactic acid peel is well tolerated and can be used for the treatment of melasma. PMID:27355080

  19. Technology and economic assessment of lactic acid production and uses

    SciTech Connect

    Datta, R.; Tsai, S.P.

    1996-03-01

    Lactic acid has been an intermediate-volume specialty chemical (world production {approximately}50,000 tons/yr) used in a wide range of food-processing and industrial applications. Potentially, it can become a very large-volume, commodity-chemical intermediate produced from carbohydrates for feedstocks of biodegradable polymers, oxygenated chemicals, environmentally friendly ``green`` solvents, and other intermediates. In the past, efficient and economical technologies for the recovery and purification of lactic acid from fermentation broths and its conversion to the chemical or polymer intermediates had been the key technology impediments and main process cost centers. Development and deployment of novel separations technologies, such as electrodialysis with bipolar membranes, extractive and catalytic distillations, and chemical conversion, can enable low-cost production with continuous processes in large-scale operations. The emerging technologies can use environmentally sound lactic acid processes to produce environmentally useful products, with attractive process economics. These technology advances and recent product and process commercialization strategies are reviewed and assessed.

  20. Dynamic modeling of lactic acid fermentation metabolism with Lactococcus lactis.

    PubMed

    Oh, Euhlim; Lu, Mingshou; Park, Changhun; Park, Changhun; Oh, Han Bin; Lee, Sang Yup; Lee, Jinwon

    2011-02-01

    A dynamic model of lactic acid fermentation using Lactococcus lactis was constructed, and a metabolic flux analysis (MFA) and metabolic control analysis (MCA) were performed to reveal an intensive metabolic understanding of lactic acid bacteria (LAB). The parameter estimation was conducted with COPASI software to construct a more accurate metabolic model. The experimental data used in the parameter estimation were obtained from an LC-MS/ MS analysis and time-course simulation study. The MFA results were a reasonable explanation of the experimental data. Through the parameter estimation, the metabolic system of lactic acid bacteria can be thoroughly understood through comparisons with the original parameters. The coefficients derived from the MCA indicated that the reaction rate of L-lactate dehydrogenase was activated by fructose 1,6-bisphosphate and pyruvate, and pyruvate appeared to be a stronger activator of L-lactate dehydrogenase than fructose 1,6-bisphosphate. Additionally, pyruvate acted as an inhibitor to pyruvate kinase and the phosphotransferase system. Glucose 6-phosphate and phosphoenolpyruvate showed activation effects on pyruvate kinase. Hexose transporter was the strongest effector on the flux through L-lactate dehydrogenase. The concentration control coefficient (CCC) showed similar results to the flux control coefficient (FCC).

  1. Lactic acid bacteria as a cell factory for riboflavin production

    PubMed Central

    Thakur, Kiran; De, Sachinandan

    2015-01-01

    Summary Consumers are increasingly becoming aware of their health and nutritional requirements, and in this context, vitamins produced in situ by microbes may suit their needs and expectations. B groups vitamins are essential components of cellular metabolism and among them riboflavin is one of the vital vitamins required by bacteria, plants, animals and humans. Here, we focus on the importance of microbial production of riboflavin over chemical synthesis. In addition, genetic abilities for riboflavin biosynthesis by lactic acid bacteria are discussed. Genetically modified strains by employing genetic engineering and chemical analogues have been developed to enhance riboflavin production. The present review attempts to collect the currently available information on riboflavin production by microbes in general, while placing greater emphasis on food grade lactic acid bacteria and human gut commensals. For designing riboflavin‐enriched functional foods, proper selection and exploitation of riboflavin‐producing lactic acid bacteria is essential. Moreover, eliminating the in situ vitamin fortification step will decrease the cost of food production. PMID:26686515

  2. The behavior and importance of lactic acid complexation in Talspeak extraction systems

    SciTech Connect

    Grimes, Travis S.; Nilsson, Mikael; Nash, Kenneth L.

    2008-07-01

    Advanced partitioning of spent nuclear fuel in the UREX +la process relies on the TALSPEAK process for separation of fission-product lanthanides from trivalent actinides. The classic TALSPEAK utilizes an aqueous medium of both lactic acid and diethylenetriaminepentaacetic acid and the extraction reagent di(2-ethylhexyl)phosphoric acid in an aromatic diluent. In this study, the specific role of lactic acid and the complexes involved in the extraction of the trivalent actinides and lanthanides have been investigated using {sup 14}C-labeled lactic acid. Our results show that lactic acid partitions between the phases in a complex fashion. (authors)

  3. Computerized image analysis for acetic acid induced intraepithelial lesions

    NASA Astrophysics Data System (ADS)

    Li, Wenjing; Ferris, Daron G.; Lieberman, Rich W.

    2008-03-01

    Cervical Intraepithelial Neoplasia (CIN) exhibits certain morphologic features that can be identified during a visual inspection exam. Immature and dysphasic cervical squamous epithelium turns white after application of acetic acid during the exam. The whitening process occurs visually over several minutes and subjectively discriminates between dysphasic and normal tissue. Digital imaging technologies allow us to assist the physician analyzing the acetic acid induced lesions (acetowhite region) in a fully automatic way. This paper reports a study designed to measure multiple parameters of the acetowhitening process from two images captured with a digital colposcope. One image is captured before the acetic acid application, and the other is captured after the acetic acid application. The spatial change of the acetowhitening is extracted using color and texture information in the post acetic acid image; the temporal change is extracted from the intensity and color changes between the post acetic acid and pre acetic acid images with an automatic alignment. The imaging and data analysis system has been evaluated with a total of 99 human subjects and demonstrate its potential to screening underserved women where access to skilled colposcopists is limited.

  4. The effect of lactic acid bacterial starter culture and chemical additives on wilted rice straw silage.

    PubMed

    Wang, Yan-Su; Shi, Wei; Huang, Lin-Ting; Ding, Cheng-Long; Dai, Chuan-Chao

    2016-04-01

    Lactic acid bacteria (LAB) are suitable for rice straw silage fermentation, but have been studied rarely, and rice straw as raw material for ensiling is difficult because of its disadvantages, such as low nutrition for microbial activities and low abundances of natural populations of LAB. So we investigated the effect of application of LAB and chemical additives on the fermentation quality and microbial community of wilted rice straw silage. Treatment with chemical additives increased the concentrations of crude protein (CP), water soluble carbohydrate (WSC), acetic acid and lactic acid, reduced the concentrations of acid detergent fiber (ADF) and neutral detergent fiber (NDF), but did not effectively inhibit the growth of spoilage organisms. Inoculation with LABs did not improve the nutritional value of the silage because of poor growth of LABs in wilted rice straw. Inoculation with LAB and addition of chemical materials improved the quality of silage similar to the effects of addition of chemical materials alone. Growth of aerobic and facultatively anaerobic bacteria was inhibited by this mixed treatment and the LAB gradually dominated the microbial community. In summary, the fermentation quality of wilted rice straw silage had improved by addition of LAB and chemical materials.

  5. Identification and quantification of antifungal compounds produced by lactic acid bacteria and propionibacteria.

    PubMed

    Le Lay, Céline; Coton, Emmanuel; Le Blay, Gwenaëlle; Chobert, Jean-Marc; Haertlé, Thomas; Choiset, Yvan; Van Long, Nicolas Nguyen; Meslet-Cladière, Laurence; Mounier, Jérôme

    2016-12-19

    Fungal growth in bakery products represents the most frequent cause of spoilage and leads to economic losses for industrials and consumers. Bacteria, such as lactic acid bacteria and propionibacteria, are commonly known to play an active role in preservation of fermented food, producing a large range of antifungal metabolites. In a previous study (Le Lay et al., 2016), an extensive screening performed both in vitro and in situ allowed for the selection of bacteria exhibiting an antifungal activity. In the present study, active supernatants against Penicillium corylophilum and Aspergillus niger were analyzed to identify and quantify the antifungal compounds associated with the observed activity. Supernatant treatments (pH neutralization, heating and addition of proteinase K) suggested that organic acids played the most important role in the antifungal activity of each tested supernatant. Different methods (HPLC, mass spectrometry, colorimetric and enzymatic assays) were then applied to analyze the supernatants and it was shown that the main antifungal compounds corresponded to lactic, acetic and propionic acids, ethanol and hydrogen peroxide, as well as other compounds present at low levels such as phenyllactic, hydroxyphenyllactic, azelaic and caproic acids. Based on these results, various combinations of the identified compounds were used to evaluate their effect on conidial germination and fungal growth of P. corylophilum and Eurotium repens. Some combinations presented the same activity than the bacterial culture supernatant thus confirming the involvement of the identified molecules in the antifungal activity. The obtained results suggested that acetic acid was mainly responsible for the antifungal activity against P. corylophilum and played an important role in E. repens inhibition.

  6. Transport of acetic acid in Zygosaccharomyces bailii: effects of ethanol and their implications on the resistance of the yeast to acidic environments.

    PubMed Central

    Sousa, M J; Miranda, L; Côrte-Real, M; Leão, C

    1996-01-01

    Cells of Zygosaccharomyces bailii ISA 1307 grown in a medium with acetic acid, ethanol, or glycerol as the sole carbon and energy source transported acetic acid by a saturable transport system. This system accepted propionic and formic acids but not lactic, sorbic, and benzoic acids. When the carbon source was glucose or fructose, the cells displayed activity of a mediated transport system specific for acetic acid, apparently not being able to recognize other monocarboxylic acids. In both types of cells, ethanol inhibited the transport of labelled acetic acid. The inhibition was noncompetitive, and the dependence of the maximum transport rate on the ethanol concentration was found to be exponential. These results reinforced the belief that, under the referenced growth conditions, the acid entered the cells mainly through a transporter protein. The simple diffusion of the undissociated acid appeared to contribute, with a relatively low weight, to the overall acid uptake. It was concluded that in Z. bailii, ethanol plays a protective role against the possible negative effects of acetic acid by inhibiting its transport and accumulation. Thus, the intracellular concentration of the acid could be maintained at levels lower than those expected if the acid entered the cells only by simple diffusion. PMID:8795203

  7. Microbiological and biochemical profile of cv. Conservolea naturally black olives during controlled fermentation with selected strains of lactic acid bacteria.

    PubMed

    Panagou, Efstathios Z; Schillinger, Ulrich; Franz, Charles M A P; Nychas, George-John E

    2008-04-01

    The effect of controlled fermentation processes on the microbial association and biochemical profile of cv. Conservolea naturally black olives processed by the traditional anaerobic method was studied. The different treatments included (a) inoculation with a commercial starter culture of Lactobacillus pentosus, (b) inoculation with a strain of Lactobacillus plantarum isolated from a fermented cassava product and (c) uninoculated spontaneous process. Microbial growth, pH, titratable acidity, organic acids and volatile compounds were monitored throughout the fermentation. The initial microbiota consisted of Gram-negative bacteria, lactic acid bacteria and yeasts. Inhibition of Gram-negative bacteria was evident in all processes. Both starter cultures were effective in establishing an accelerated fermentation process and reduced the survival period of Gram-negative bacteria by 5 days compared with the spontaneous process, minimizing thus the likelihood of spoilage. Higher acidification of the brines was observed in inoculated processes without any significant difference between the two selected starter cultures (113.5 and 117.6mM for L. plantarum and L. pentosus, respectively). L. pentosus was also determined as the major species present during the whole process of spontaneous olive fermentation. It is characteristic that lactic acid fermentation was also initiated rapidly in the spontaneous process, as the conditions of fermentation, mainly the low salt level (6%, w/v) favored the dominance of lactic acid bacteria over yeasts. Lactic, acetic and propionic were the organic acids detected by HPLC in considerable amounts, whereas citric and malic acids were also present at low levels and degraded completely during the processes. Ethanol, methanol, acetaldehyde, ethyl acetate were the major volatile compounds identified by GC. Their concentrations varied among the different treatments, reflecting varying degrees of microbial activity in the brines. The results obtained

  8. Uranyl complexes of n-alkanediaminotetra-acetic acids.

    PubMed

    Gonçalves, M L; Mota, A M; da Silva, J J

    1984-07-01

    The uranyl complexes of n-propanediaminetetra-acetic acid, n-butanediaminetetra-acetic acid and n-hexanediaminetetra-acetic acid have been studied by potentiometry, with computer evaluation of the titration data by the MINIQUAD program. Stability constants of the 1:1 and 2:1 metal:ligand chelates have been determined as well as the respective hydrolysis and polymerization constants at 25 degrees in 0.10M and 1.00M KNO(3). The influence of the length of the alkane chain of the ligands on the complexes formed is discussed.

  9. Disproportionation Kinetics of Hypoiodous Acid As Catalyzed and Suppressed by Acetic Acid-Acetate Buffer.

    PubMed

    Urbansky, Edward T.; Cooper, Brian T.; Margerum, Dale W.

    1997-03-26

    The kinetics of the disproportionation of hypoiodous acid to give iodine and iodate ion (5HOI right harpoon over left harpoon 2I(2) + IO(3)(-) + H(+) + 2H(2)O) are investigated in aqueous acetic acid-sodium acetate buffer. The rate of iodine formation is followed photometrically at -log [H(+)] = 3.50, 4.00, 4.50, and 5.00, &mgr; = 0.50 M (NaClO(4)), and 25.0 degrees C. Both catalytic and inhibitory buffer effects are observed. The first process is proposed to be a disproportionation of iodine(I) to give HOIO and I(-); the iodide then reacts with HOI to give I(2). The reactive species (acetato-O)iodine(I), CH(3)CO(2)I, is postulated to increase the rate by assisting in the formation of I(2)O, a steady-state species that hydrolyzes to give HOIO and I(2). Inhibition is postulated to result from the formation of the stable ion bis(acetato-O)iodate(I), (CH(3)CO(2))(2)I(-), as buffer concentration is increased. This species is observed spectrophotometrically with a UV absorption shoulder (lambda = 266 nm; epsilon = 530 M(-)(1) cm(-)(1)). The second process is proposed to be a disproportionation of HOIO to give IO(3)(-) and I(2). Above 1 M total buffer, the reaction becomes reversible with less than 90% I(2) formation. Rate and equilibrium constants are resolved and reported for the proposed mechanism.

  10. Antifungal sourdough lactic acid bacteria as biopreservation tool in quinoa and rice bread.

    PubMed

    Axel, Claudia; Brosnan, Brid; Zannini, Emanuele; Furey, Ambrose; Coffey, Aidan; Arendt, Elke K

    2016-12-19

    The use of sourdough fermented with specific strains of antifungal lactic acid bacteria can reduce chemical preservatives in bakery products. The main objective of this study was to investigate the production of antifungal carboxylic acids after sourdough fermentation of quinoa and rice flour using the antifungal strains Lactobacillus reuteri R29 and Lactobacillus brevis R2Δ as bioprotective cultures and the non-antifungal L. brevis L1105 as a negative control strain. The impact of the fermentation substrate was evaluated in terms of metabolic activity, acidification pattern and quantity of antifungal carboxylic acids. These in situ produced compounds (n=20) were extracted from the sourdough using a QuEChERS method and detected by a new UHPLC-MS/MS chromatography. Furthermore, the sourdough was applied in situ using durability tests against environmental moulds to investigate the biopreservative potential to prolong the shelf life of bread. Organic acid production and TTA values were lowest in rice sourdough. The sourdough fermentation of the different flour substrates generated a complex and significantly different profile of carboxylic acids. Extracted quinoa sourdough detected the greatest number of carboxylic acids (n=11) at a much higher concentration than what was detected from rice sourdough (n=9). Comparing the lactic acid bacteria strains, L. reuteri R29 fermented sourdoughs contained generally higher concentrations of acetic and lactic acid but also the carboxylic acids. Among them, 3-phenyllactic acid and 2-hydroxyisocaproic acid were present at a significant concentration. This was correlated with the superior protein content of quinoa flour and its high protease activity. With the addition of L. reuteri R29 inoculated sourdough, the shelf life was extended by 2 days for quinoa (+100%) and rice bread (+67%) when compared to the non-acidified controls. The L. brevis R2Δ fermented sourdough bread reached a shelf life of 4 days for quinoa (+100%) and

  11. Sequential injection redox or acid-base titration for determination of ascorbic acid or acetic acid.

    PubMed

    Lenghor, Narong; Jakmunee, Jaroon; Vilen, Michael; Sara, Rolf; Christian, Gary D; Grudpan, Kate

    2002-12-06

    Two sequential injection titration systems with spectrophotometric detection have been developed. The first system for determination of ascorbic acid was based on redox reaction between ascorbic acid and permanganate in an acidic medium and lead to a decrease in color intensity of permanganate, monitored at 525 nm. A linear dependence of peak area obtained with ascorbic acid concentration up to 1200 mg l(-1) was achieved. The relative standard deviation for 11 replicate determinations of 400 mg l(-1) ascorbic acid was 2.9%. The second system, for acetic acid determination, was based on acid-base titration of acetic acid with sodium hydroxide using phenolphthalein as an indicator. The decrease in color intensity of the indicator was proportional to the acid content. A linear calibration graph in the range of 2-8% w v(-1) of acetic acid with a relative standard deviation of 4.8% (5.0% w v(-1) acetic acid, n=11) was obtained. Sample throughputs of 60 h(-1) were achieved for both systems. The systems were successfully applied for the assays of ascorbic acid in vitamin C tablets and acetic acid content in vinegars, respectively.

  12. Flow Cytometric Assessment of Viability of Lactic Acid Bacteria

    PubMed Central

    Bunthof, Christine J.; Bloemen, Karen; Breeuwer, Pieter; Rombouts, Frank M.; Abee, Tjakko

    2001-01-01

    The viability of lactic acid bacteria is crucial for their applications as dairy starters and as probiotics. We investigated the usefulness of flow cytometry (FCM) for viability assessment of lactic acid bacteria. The esterase substrate carboxyfluorescein diacetate (cFDA) and the dye exclusion DNA binding probes propidium iodide (PI) and TOTO-1 were tested for live/dead discrimination using a Lactococcus, a Streptococcus, three Lactobacillus, two Leuconostoc, an Enterococcus, and a Pediococcus species. Plate count experiments were performed to validate the results of the FCM assays. The results showed that cFDA was an accurate stain for live cells; in exponential-phase cultures almost all cells were labeled, while 70°C heat-killed cultures were left unstained. PI did not give clear live/dead discrimination for some of the species. TOTO-1, on the other hand, gave clear discrimination between live and dead cells. The combination of cFDA and TOTO-1 gave the best results. Well-separated subpopulations of live and dead cells could be detected with FCM. Cell sorting of the subpopulations and subsequent plating on agar medium provided direct evidence that cFDA labels the culturable subpopulation and that TOTO-1 labels the nonculturable subpopulation. Applied to cultures exposed to deconjugated bile salts or to acid, cFDA and TOTO-1 proved to be accurate indicators of culturability. Our experiments with lactic acid bacteria demonstrated that the combination of cFDA and TOTO-1 makes an excellent live/dead assay with versatile applications. PMID:11319119

  13. The Promotion of Erythropoiesis via the Regulation of Reactive Oxygen Species by Lactic Acid

    PubMed Central

    Luo, Shun-Tao; Zhang, Dong-Mei; Qin, Qing; Lu, Lian; Luo, Min; Guo, Fu-Chun; Shi, Hua-Shan; Jiang, Li; Shao, Bin; Li, Meng; Yang, Han-Shuo; Wei, Yu-Quan

    2017-01-01

    The simultaneous increases in blood lactic acid and erythrocytes after intense exercise could suggest a link between lactate and the erythropoiesis. However, the effects of lactic acid on erythropoiesis remain to be elucidated. Here, we utilized a mouse model to determine the role of lactic acid in this process in parallel with studies using leukaemic K562 cells. Treatment of K562 cells in vitro with lactic acid increased the mRNA and protein expression of haemoglobin genes and the frequency of GPA+ cells. Also, increases in haematocrit and CD71−/Ter119+ erythroid cells were observed in lactic acid-treated mice, which showed a physiological increase in blood lactate. Mouse bone marrow CD34+/CD117− cells showed an increase in erythroid burst-forming units after stimulation with lactic acid in vitro. Furthermore, lactic acid increased the intracellular reactive oxygen species (ROS) content in bone marrow and in K562 cells. Erythroid differentiation induced in Haematopoietic Stem Cells (HSCs) and K562 cells by lactic acid was abolished by reducing ROS levels with SOD or 2-mercaptoethanol, which suggests that ROS is a critical regulator of this process. These findings provide a better understanding of the role of lactic acid in cellular metabolism and physiological functions. PMID:28165036

  14. An integrated bioconversion process for the production of L-lactic acid from starchy feedstocks

    SciTech Connect

    Tsai, S.P.; Moon, S.H.

    1997-07-01

    The potential market for lactic acid as the feedstock for biodegradable polymers, oxygenated chemicals, and specialty chemicals is significant. L-lactic acid is often the desired enantiomer for such applications. However, stereospecific lactobacilli do not metabolize starch efficiently. In this work, Argonne researchers have developed a process to convert starchy feedstocks into L-lactic acid. The processing steps include starch recovery, continuous liquefaction, and simultaneous saccharification and fermentation. Over 100 g/L of lactic acid was produced in less than 48 h. The optical purity of the product was greater than 95%. This process has potential economical advantages over the conventional process.

  15. The Promotion of Erythropoiesis via the Regulation of Reactive Oxygen Species by Lactic Acid.

    PubMed

    Luo, Shun-Tao; Zhang, Dong-Mei; Qin, Qing; Lu, Lian; Luo, Min; Guo, Fu-Chun; Shi, Hua-Shan; Jiang, Li; Shao, Bin; Li, Meng; Yang, Han-Shuo; Wei, Yu-Quan

    2017-02-06

    The simultaneous increases in blood lactic acid and erythrocytes after intense exercise could suggest a link between lactate and the erythropoiesis. However, the effects of lactic acid on erythropoiesis remain to be elucidated. Here, we utilized a mouse model to determine the role of lactic acid in this process in parallel with studies using leukaemic K562 cells. Treatment of K562 cells in vitro with lactic acid increased the mRNA and protein expression of haemoglobin genes and the frequency of GPA(+) cells. Also, increases in haematocrit and CD71(-)/Ter119(+) erythroid cells were observed in lactic acid-treated mice, which showed a physiological increase in blood lactate. Mouse bone marrow CD34(+)/CD117(-) cells showed an increase in erythroid burst-forming units after stimulation with lactic acid in vitro. Furthermore, lactic acid increased the intracellular reactive oxygen species (ROS) content in bone marrow and in K562 cells. Erythroid differentiation induced in Haematopoietic Stem Cells (HSCs) and K562 cells by lactic acid was abolished by reducing ROS levels with SOD or 2-mercaptoethanol, which suggests that ROS is a critical regulator of this process. These findings provide a better understanding of the role of lactic acid in cellular metabolism and physiological functions.

  16. l-(+)-Lactic acid production by Lactobacillus rhamnosus B103 from dairy industry waste.

    PubMed

    Bernardo, Marcela Piassi; Coelho, Luciana Fontes; Sass, Daiane Cristina; Contiero, Jonas

    2016-01-01

    Lactic acid, which can be obtained through fermentation, is an interesting compound because it can be utilized in different fields, such as in the food, pharmaceutical and chemical industries as a bio-based molecule for bio-refinery. In addition, lactic acid has recently gained more interest due to the possibility of manufacturing poly(lactic acid), a green polymer that can replace petroleum-derived plastics and be applied in medicine for the regeneration of tissues and in sutures, repairs and implants. One of the great advantages of fermentation is the possibility of using agribusiness wastes to obtain optically pure lactic acid. The conventional batch process of fermentation has some disadvantages such as inhibition by the substrate or the final product. To avoid these problems, this study was focused on improving the production of lactic acid through different feeding strategies using whey, a residue of agribusiness. The downstream process is a significant bottleneck because cost-effective methods of producing high-purity lactic acid are lacking. Thus, the investigation of different methods for the purification of lactic acid was one of the aims of this work. The pH-stat strategy showed the maximum production of lactic acid of 143.7g/L. Following purification of the lactic acid sample, recovery of reducing sugars and protein and color removal were 0.28%, 100% and 100%, respectively.

  17. Enterococcus faecium QU 50: a novel thermophilic lactic acid bacterium for high-yield l-lactic acid production from xylose.

    PubMed

    Abdel-Rahman, Mohamed Ali; Tashiro, Yukihiro; Zendo, Takeshi; Sakai, Kenji; Sonomoto, Kenji

    2015-01-01

    Production of optically pure lactic acid from lignocellulosic material for commercial purposes is hampered by several difficulties, including heterofermentation of pentose sugars and high energy consumption by mesophilic lactic acid bacteria. Here, we report a novel lactic acid bacterium, strain QU 50, that has the potential to produce optically pure l-lactic acid (≥99.2%) in a homofermentative manner from xylose under thermophilic conditions. Strain QU 50 was isolated from Egyptian fertile soil and identified as Enterococcus faecium QU 50 by analyzing its sugar fermentation pattern and 16S rRNA gene sequence. Enterococcus faecium QU 50 fermented xylose efficiently to produce lactic acid over wide pH (6.0-10.0) and temperature ranges (30-52°C), with a pH of 6.5 and temperature of 50°C being optimal. To our knowledge, this is the first report of homofermentative lactic acid production from xylose by a thermophilic lactic acid bacterium.

  18. Ethanol Production by Selected Intestinal Microorganisms and Lactic Acid Bacteria Growing under Different Nutritional Conditions

    PubMed Central

    Elshaghabee, Fouad M. F.; Bockelmann, Wilhelm; Meske, Diana; de Vrese, Michael; Walte, Hans-Georg; Schrezenmeir, Juergen; Heller, Knut J.

    2016-01-01

    To gain some specific insight into the roles microorganisms might play in non-alcoholic fatty liver disease (NAFLD), some intestinal and lactic acid bacteria and one yeast (Anaerostipes caccae, Bacteroides thetaiotaomicron, Bifidobacterium longum, Enterococcus fecalis, Escherichia coli, Lactobacillus acidophilus, Lactobacillus fermentum, Lactobacillus plantarum, Weissella confusa, Saccharomyces cerevisiae) were characterized by high performance liquid chromatography for production of ethanol when grown on different carbohydrates: hexoses (glucose and fructose), pentoses (arabinose and ribose), disaccharides (lactose and lactulose), and inulin. Highest amounts of ethanol were produced by S. cerevisiae, L. fermentum, and W. confusa on glucose and by S. cerevisiae and W. confusa on fructose. Due to mannitol-dehydrogenase expressed in L. fermentum, ethanol production on fructose was significantly (P < 0.05) reduced. Pyruvate and citrate, two potential electron acceptors for regeneration of NAD+/NADP+, drastically reduced ethanol production with acetate produced instead in L. fermentum grown on glucose and W. confusa grown on glucose and fructose, respectively. In fecal slurries prepared from feces of four overweight volunteers, ethanol was found to be produced upon addition of fructose. Addition of A. caccae, L. acidophilus, L. fermentum, as well as citrate and pyruvate, respectively, abolished ethanol production. However, addition of W. confusa resulted in significantly (P < 0.05) increased production of ethanol. These results indicate that microorganisms like W. confusa, a hetero-fermentative, mannitol-dehydrogenase negative lactic acid bacterium, may promote NAFLD through ethanol produced from sugar fermentation, while other intestinal bacteria and homo- and hetero-fermentative but mannitol-dehydrogenase positive lactic acid bacteria may not promote NAFLD. Also, our studies indicate that dietary factors interfering with gastrointestinal microbiota and microbial

  19. Degradation by acetic acid for crystalline Si photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Masuda, Atsushi; Uchiyama, Naomi; Hara, Yukiko

    2015-04-01

    The degradation of crystalline Si photovoltaic modules during damp-heat test was studied using some test modules with and without polymer film insertion by observing electrical and electroluminescence properties and by chemical analyses. Acetic acid generated by the hydrolysis decomposition of ethylene vinyl acetate used as an encapsulant is the main origin of degradation. The change in electroluminescence images is explained on the basis of the corrosion of electrodes by acetic acid. On the other hand, little change was observed at the pn junction even after damp-heat test for a long time. Therefore, carrier generation occurs even after degradation; however, such generated carriers cannot be collected owing to corrosion of electrodes. The guiding principle that module structure and module materials without saving acetic acid into the modules was obtained.

  20. Lactic acid fermentation of food waste for swine feed.

    PubMed

    Yang, S Y; Ji, K S; Baik, Y H; Kwak, W S; McCaskey, T A

    2006-10-01

    This study was conducted to determine the effects of lactic acid bacteria (LAB, Lactobacillus salivarius) inoculation on the microbial, physical and chemical properties of food waste mixture (FWM) stored at ambient temperature (25 degrees C) for 10 and 30 days. A complete pig diet including restaurant food waste, bakery by-product, barley and wheat bran, and broiler poultry litter was amended with LAB at the levels of 0.1%, 0.2%, 0.5% and 1.0% and fermented anaerobically. These treatments were compared with intact FWM before storage and non-anaerobically stored FWM. Non-anaerobic storage of FWM showed microbial putrefaction with the loss (P < 0.05) of water and water soluble carbohydrate (WSC) and increases (P < 0.005) in protein and fiber. Anaerobic fermentation of FWM with or without LAB seemed effective in both 10- and 30-day-storage. The addition of LAB inoculants to FWM showed a linear trend (P < 0.05) toward an increase in the number of total and lactic acid bacteria and toward the nutritional improvement with WSC increased and fiber decreased. Long-term (30 days) storage resulted in consistent reduction (P < 0.05) in numbers of total and lactic acid bacteria and pH and showed little change in chemical components, compared with short-term (10 days) storage. On the basis of these results, LAB inoculation improved fermentative characteristics of FWM. Among anaerobic treatments, further WSC increase and NDF reduction did not occur (P > 0.05) when LAB-added levels were over 0.2%. Based on these observations the optimum level of LAB addition to FWM was 0.2%.

  1. Laser photocoagulation stops diabetic retinopathy by controlling lactic acid formation

    NASA Astrophysics Data System (ADS)

    Wolbarsht, Myron L.

    1994-08-01

    Many different types of proliferative retinopathy induced by various types of initial disorders have a common pathology in their mid and terminal stages. Thus, proper therapy is devoted toward elimination of the initial cause as well as alleviation of the proliferative processes. Vasodilatation, which is an initial symptom of diabetes, is itself destructive to the retinal capillary bed and appears to be a constant feature in all stages of diabetic retinopathy. In the mid and late stages, the vasodilatation seems very dependent upon capillary dropout, whereas the initial vasodilatation may derive from quite different causes. The efficacy of photocoagulation as a therapy for all stages seems to derive from decreasing the metabolism in the photoreceptor layer sufficiently to result in vasoconstriction of the retinal vessels. A model is proposed to show how diabetes, by altering the metabolism in the photoreceptor layer to produce excess lactic acid, causes the initial vasodilatation. The lactic acid also induces free radical (superoxide) formation; both act together to destroy the retinal capillary bed followed by vasoproliferation. Photocoagulation, thus, is even more appropriate for this particular syndrome than previously had been thought, as it not only reduces potentially destructive vasodilatation but also removes the metabolic cause of the free radical induced destruction of the capillary endothelium which is the initial step in capillary drop-out. A review of the present data indicates that the best type of pan- retinal photocoagulation is a very light type affecting the photoreceptors only with a minimal amount of damage to other parts of retina and the vessels in the choroid. The possible use of photochemical types of destruction of the photoreceptor as a therapeutic modality is attractive, but it is certainly too speculative to use until more detailed investigations have been completed. However, the basic therapeutic approach of choice may be to prevent the

  2. Identification of lactic acid bacteria constituting the predominating microflora in an acid-fermented condiment (tempoyak) popular in Malaysia.

    PubMed

    Leisner, J J; Vancanneyt, M; Rusul, G; Pot, B; Lefebvre, K; Fresi, A; Tee, L K

    2001-01-22

    Tempoyak is a traditional Malaysian fermented condiment made from the pulp of the durian fruit (Durio zibethinus). Salt is sometime added to proceed fermentation at ambient temperature. In various samples obtained from night markets, lactic acid bacteria (LAB) were the predominant microorganisms, ranging from log 8.4 to log 9.2 cfu g(-1). No other microorganisms were present to such a level. These samples contained reduced amount of saccharose, glucose and fructose but increased amount of D- and L-lactic acid and acetic acid compared with samples of non-fermented durian fruit. Sixty-four isolates of LAB were divided into five groups by use of a few phenotypic tests. A total of 38 strains of LAB were selected for comparison by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of their whole cell protein patterns with a SDS-PAGE database of LAB. These strains were also examined for their carbohydrate fermentation patterns by use of API 50 CH. Isolates belonging to the Lactobacillus plantarum group were shown to be the predominant members of the LAB flora. In addition, isolates belonging to the Lactobacillus brevis group, Leuconostoc mesenteroides, Lactobacillus mali, Lactobacilus fermentum and an unidentified Lactobacillus sp. were also observed. A high degree of diversity among isolates belonging to the Lb. plantarum group was demonstrated by analysis of their plasmid profiles.

  3. Tetrazole acetic acid: Tautomers, conformers, and isomerization

    SciTech Connect

    Araujo-Andrade, C.; Reva, I. Fausto, R.

    2014-02-14

    Monomers of (tetrazol-5-yl)-acetic acid (TAA) were obtained by sublimation of the crystalline compound and the resulting vapors were isolated in cryogenic nitrogen matrices at 13 K. The conformational and tautomeric composition of TAA in the matrix was characterized by infrared spectroscopy and vibrational calculations carried out at the B3LYP/6-311++G(d,p) level. TAA may adopt two tautomeric modifications, 1H- and 2H-, depending on the position of the annular hydrogen atom. Two-dimensional potential energy surfaces (PESs) of TAA were theoretically calculated at the MP2/6-311++G(d,p) level, for each tautomer. Four and six symmetry-unique minima were located on these PESs, for 1H- and 2H-TAA, respectively. The energetics of the detected minima was subsequently refined by calculations at the QCISD level. Two 1H- and three 2H-conformers fall within the 0–8 kJ mol{sup −1} energy range and should be appreciably populated at the sublimation temperature (∼330 K). Observation of only one conformer for each tautomer (1ccc and 2pcc) is explained in terms of calculated barriers to conformational rearrangements. All conformers with the cis O=COH moiety are separated by low barriers (less than 10 kJ mol{sup −1}) and collapse to the most stable 1ccc (1H-) and 2pcc (2H-) forms during deposition of the matrix. On the trans O=COH surfaces, the relative energies are very high (between 12 and 27 kJ mol{sup −1}). The trans forms are not thermally populated at the sublimation conditions and were not detected in matrices. One high-energy form in each tautomer, 1cct (1H-) and 2pct (2H-), was found to differ from the most stable form only by rotation of the OH group and separated from other forms by high barriers. This opened a perspective for their stabilization in a matrix. 1cct and 2pct were generated in the matrices selectively by means of narrow-band near-infrared (NIR) irradiations of the samples at 6920 and 6937 cm{sup −1}, where the first OH stretching overtone

  4. Using banana to generate lactic acid through batch process fermentation.

    PubMed

    Chan-Blanco, Y; Bonilla-Leiva, A R; Velázquez, A C

    2003-12-01

    We evaluated the usefulness of waste banana for generating lactic acid through batch fermentation, using Lactobacillus casei under three treatments. Two treatments consisted of substrates of diluted banana purée, one of which was enriched with salts and amino acids. The control treatment comprised a substrate suitable for L. casei growth. When fermentation was evaluated over time, significant differences (P<0.05) were found in the three treatments for each of five variables analyzed (generation and productivity of lactic acid, and consumption of glucose, fructose, and sucrose). Maximum productivity was (in g l(-1) h(-1)) 0.13 for the regular banana treatment, 1.49 for the enriched banana, and 1.48 for the control, with no significant differences found between the latter two treatments. Glucose consumption curves showed that L. casei made greater use of the substrate in the enriched banana and control treatments than in the regular banana treatment. For fructose intake, the enriched banana treatment showed significantly better (P<0.05) results than the regular one. Sucrose consumption was insignificant (P<0.05), probably because fermentation time was too short. Even when enriched, diluted banana purée is an ineffective substrate for L. casei, probably because it lacks nutrients.

  5. In vaginal fluid, bacteria associated with bacterial vaginosis can be suppressed with lactic acid but not hydrogen peroxide

    PubMed Central

    2011-01-01

    Background Hydrogen peroxide (H2O2) produced by vaginal lactobacilli is generally believed to protect against bacteria associated with bacterial vaginosis (BV), and strains of lactobacilli that can produce H2O2 are being developed as vaginal probiotics. However, evidence that led to this belief was based in part on non-physiological conditions, antioxidant-free aerobic conditions selected to maximize both production and microbicidal activity of H2O2. Here we used conditions more like those in vivo to compare the effects of physiologically plausible concentrations of H2O2 and lactic acid on a broad range of BV-associated bacteria and vaginal lactobacilli. Methods Anaerobic cultures of seventeen species of BV-associated bacteria and four species of vaginal lactobacilli were exposed to H2O2, lactic acid, or acetic acid at pH 7.0 and pH 4.5. After two hours, the remaining viable bacteria were enumerated by growth on agar media plates. The effect of vaginal fluid (VF) on the microbicidal activities of H2O2 and lactic acid was also measured. Results Physiological concentrations of H2O2 (< 100 μM) failed to inactivate any of the BV-associated bacteria tested, even in the presence of human myeloperoxidase (MPO) that increases the microbicidal activity of H2O2. At 10 mM, H2O2 inactivated all four species of vaginal lactobacilli but only one of seventeen species of BV-associated bacteria. Moreover, the addition of just 1% vaginal fluid (VF) blocked the microbicidal activity of 1 M H2O2. In contrast, lactic acid at physiological concentrations (55-111 mM) and pH (4.5) inactivated all the BV-associated bacteria tested, and had no detectable effect on the vaginal lactobacilli. Also, the addition of 10% VF did not block the microbicidal activity of lactic acid. Conclusions Under optimal, anaerobic growth conditions, physiological concentrations of lactic acid inactivated BV-associated bacteria without affecting vaginal lactobacilli, whereas physiological concentrations of H2O2

  6. Fast identification of wine related lactic acid bacteria by multiplex PCR.

    PubMed

    Petri, A; Pfannebecker, J; Fröhlich, J; König, H

    2013-02-01

    The microflora of must and wine consists of yeasts, acetic acid bacteria and lactic acid bacteria (LAB). The latter group plays an important role for wine quality. The malolactic fermentation carried out by LAB leads to deacidification and stabilisation of wines. Nevertheless, LAB are often associated with wine spoilage. They are mainly responsible for the formation of biogenic amines. Furthermore, some strains produce exopolysaccharide slimes, acetic acid, diacetyl and other off-flavours. In this context a better monitoring of the vinification process is crucial to improve wine quality. Moreover, a lot of biodiversity studies would also profit from a fast and reliable identification method. In this study, we propose a species-specific multiplex PCR system for a rapid and simultaneous detection of 13 LAB species, frequently occurring in must or wine: Lactobacillus brevis, Lb. buchneri, Lb. curvatus, Lb. hilgardii, Lb. plantarum, Leuconostoc mesenteroides, Oenococcus oeni, Pediococcus acidilactici, P. damnosus, P. inopinatus, P. parvulus, P. pentosaceus and Weissella paramesenteroides.

  7. Safety evaluation of poly(lactic-co-glycolic acid)/poly(lactic-acid) microspheres through intravitreal injection in rabbits.

    PubMed

    Rong, Xianfang; Yuan, Weien; Lu, Yi; Mo, Xiaofen

    2014-01-01

    Poly(lactic-co-glycolic acid) (PLGA) and/or poly(lactic-acid) (PLA) microspheres are important drug delivery systems. This study investigated eye biocompatibility and safety of PLGA/PLA microspheres through intravitreal injection in rabbits. Normal New Zealand rabbits were randomly selected and received intravitreal administration of different doses (low, medium, or high) of PLGA/PLA microspheres and erythropoietin-loaded PLGA/PLA microspheres. The animals were clinically examined and sacrificed at 1, 2, 4, 8, and 12 weeks postadministration, and retinal tissues were prepared for analysis. Retinal reactions to the microspheres were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick end staining and glial fibrillary acidic protein immunohistochemistry. Retinal structure changes were assessed by hematoxylin and eosin staining and transmission electron microscopy. Finally, retinal function influences were explored by the electroretinography test. Terminal deoxynucleotidyl transferase-mediated dUTP nick end staining revealed no apoptotic cells in the injected retinas; immunohistochemistry did not detect any increased glial fibrillary acidic protein expression. Hematoxylin and eosin staining and transmission electron microscopy revealed no micro- or ultrastructure changes in the retinas at different time points postintravitreal injection. The electroretinography test showed no significant influence of scotopic or photopic amplitudes. The results demonstrated that PLGA/PLA microspheres did not cause retinal histological changes or functional damage and were biocompatible and safe enough for intravitreal injection in rabbits for controlled drug delivery.

  8. Improvement of lactic acid production in Saccharomyces cerevisiae by a deletion of ssb1.

    PubMed

    Lee, Jinsuk J; Crook, Nathan; Sun, Jie; Alper, Hal S

    2016-01-01

    Polylactic acid (PLA) is an important renewable polymer, but current processes for producing its precursor, lactic acid, suffer from process inefficiencies related to the use of bacterial hosts. Therefore, improving the capacity of Saccharomyces cerevisiae to produce lactic acid is a promising approach to improve industrial production of lactic acid. As one such improvement required, the lactic acid tolerance of yeast must be significantly increased. To enable improved tolerance, we employed an RNAi-mediated genome-wide expression knockdown approach as a means to rapidly identify potential genetic targets. In this approach, several gene knockdown targets were identified which confer increased acid tolerance to S. cerevisiae BY4741, of which knockdown of the ribosome-associated chaperone SSB1 conferred the highest increase (52%). This target was then transferred into a lactic acid-overproducing strain of S. cerevisiae CEN.PK in the form of a knockout and the resulting strain demonstrated up to 33% increased cell growth, 58% increased glucose consumption, and 60% increased L-lactic acid production. As SSB1 contains a close functional homolog SSB2 in yeast, this result was counterintuitive and may point to as-yet-undefined functional differences between SSB1 and SSB2 related to lactic acid production. The final strain produced over 50 g/L of lactic acid in under 60 h of fermentation.

  9. Impact property enhancement of poly (lactic acid) with different flexible copolymers

    NASA Astrophysics Data System (ADS)

    Likittanaprasong, N.; Seadan, M.; Suttiruengwong, S.

    2015-07-01

    The objective of this work was to improve the impact property of Poly (lactic acid) (PLA) by blending with different copolymers. Six flexible copolymers, namely, acrylonitrile butadiene styrene (ABS) powder, Biomax, polybutyrate adipate co-terephthalate (PBAT), polyether block amide (PEBAX), ethylene-vinyl acetate (EVA) and ethylene acrylic elastomer (EAE), with loading less than 20wt% were used and compared. The rheological, mechanical and morphological properties of samples were investigated by melt flow index, tensile testing, impact testing and scanning electron microscope (SEM), respectively. It was found that PLA added 20wt% EAE showed the highest impact strength (59.5 kJ/m2), which was 22 times higher than neat PLA. The elongation at break was also increased by 12 folds compared to neat PLA. The SEM images showed good interface and distribution for PLA containing 20wt% EAE, 15 phr Biomax and 20 wt% PEBAX.

  10. d-lactic acid production from renewable lignocellulosic biomass via genetically modified Lactobacillus plantarum.

    PubMed

    Zhang, Yixing; Kumar, Amit; Hardwidge, Philip R; Tanaka, Tsutomu; Kondo, Akihiko; Vadlani, Praveen V

    2016-03-01

    d-lactic acid is of great interest because of increasing demand for biobased poly-lactic acid (PLA). Blending poly-l-lactic acid with poly-d-lactic acid greatly improves PLA's mechanical and physical properties. Corn stover and sorghum stalks treated with 1% sodium hydroxide were investigated as possible substrates for d-lactic acid production by both sequential saccharification and fermentation and simultaneous saccharification and cofermentation (SSCF). A commercial cellulase (Cellic CTec2) was used for hydrolysis of lignocellulosic biomass and an l-lactate-deficient mutant strain Lactobacillus plantarum NCIMB 8826 ldhL1 and its derivative harboring a xylose assimilation plasmid (ΔldhL1-pCU-PxylAB) were used for fermentation. The SSCF process demonstrated the advantage of avoiding feedback inhibition of released sugars from lignocellulosic biomass, thus significantly improving d-lactic acid yield and productivity. d-lactic acid (27.3 g L(-1) ) and productivity (0.75 g L(-1) h(-1) ) was obtained from corn stover and d-lactic acid (22.0 g L(-1) ) and productivity (0.65 g L(-1) h(-1) ) was obtained from sorghum stalks using ΔldhL1-pCU-PxylAB via the SSCF process. The recombinant strain produced a higher concentration of d-lactic acid than the mutant strain by using the xylose present in lignocellulosic biomass. Our findings demonstrate the potential of using renewable lignocellulosic biomass as an alternative to conventional feedstocks with metabolically engineered lactic acid bacteria to produce d-lactic acid. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:271-278, 2016.

  11. Enhanced D-lactic acid production from renewable resources using engineered Lactobacillus plantarum.

    PubMed

    Zhang, Yixing; Vadlani, Praveen V; Kumar, Amit; Hardwidge, Philip R; Govind, Revathi; Tanaka, Tsutomu; Kondo, Akihiko

    2016-01-01

    D-lactic acid is used as a monomer in the production of poly-D-lactic acid (PDLA), which is used to form heat-resistant stereocomplex poly-lactic acid. To produce cost-effective D-lactic acid by using all sugars derived from biomass efficiently, xylose-assimilating genes encoding xylose isomerase and xylulokinase were cloned into an L-lactate-deficient strain, Lactobacillus plantarum. The resulting recombinant strain, namely L. plantarum NCIMB 8826 ∆ldhL1-pLEM-xylAB, was able to produce D-lactic acid (at optical purity >99 %) from xylose at a yield of 0.53 g g(-1). Simultaneous utilization of glucose and xylose to produce D-lactic acid was also achieved by this strain, and 47.2 g L(-1) of D-lactic acid was produced from 37.5 g L(-1) glucose and 19.7 g L(-1) xylose. Corn stover and soybean meal extract (SBME) were evaluated as cost-effective medium components for D-lactic acid production. Optimization of medium composition using response surface methodology resulted in 30 % reduction in enzyme loading and 70 % reduction in peptone concentration. In addition, we successfully demonstrated D-lactic acid fermentation from corn stover and SBME in a fed-batch fermentation, which yielded 61.4 g L(-1) D-lactic acid with an overall yield of 0.77 g g(-1). All these approaches are geared to attaining high D-lactic acid production from biomass sugars to produce low-cost, highly thermostable biodegradable plastics.

  12. Phenolic Biotransformations during Conversion of Ferulic Acid to Vanillin by Lactic Acid Bacteria

    PubMed Central

    Kaur, Baljinder; Kumar, Balvir

    2013-01-01

    Vanillin is widely used as food additive and as a masking agent in various pharmaceutical formulations. Ferulic acid is an important precursor of vanillin that is available in abundance in cell walls of cereals like wheat, corn, and rice. Phenolic biotransformations can occur during growth of lactic acid bacteria (LAB), and their production can be made feasible using specialized LAB strains that have been reported to produce ferulic acid esterases. The present study aimed at screening a panel of LAB isolates for their ability to release phenolics from agrowaste materials like rice bran and their biotransformation to industrially important compounds such as ferulic acid, 4-ethyl phenol, vanillic acid, vanillin, and vanillyl alcohol. Bacterial isolates were evaluated using ferulic acid esterase, ferulic acid decarboxylase, and vanillin dehydrogenase assays. This work highlights the importance of lactic acid bacteria in phenolic biotransformations for the development of food grade flavours and additives. PMID:24066293

  13. Evolution of the Lactic Acid Bacterial Community during Malt Whisky Fermentation: a Polyphasic Study

    PubMed Central

    van Beek, Sylvie; Priest, Fergus G.

    2002-01-01

    The development of the lactic acid bacterial community in a commercial malt whisky fermentation occurred in three broad phases. Initially, bacteria were inhibited by strong yeast growth. Fluorescence microscopy and environmental scanning electron microscopy revealed, in this early stage, both cocci and rods that were at least partly derived from the wort and yeast but also stemmed from the distillery plant. Denaturing gradient gel electrophoresis (DGGE) of partial 16S rRNA genes and sequence analysis revealed cocci related to Streptococcus thermophilus or Saccharococcus thermophilus, Lactobacillus brevis, and Lactobacillus fermentum. The middle phase began 35 to 40 h after yeast inoculation and was characterized by exponential growth of lactobacilli and residual yeast metabolism. Lactobacillus casei or Lactobacillus paracasei, L. fermentum, and Lactobacillus ferintoshensis were detected in samples of fermenting wort examined by DGGE during this stage. Bacterial growth was accompanied by the accumulation of acetic and lactic acids and the metabolism of residual maltooligosaccharides. By 70 h, two new PCR bands were detected on DGGE gels, and the associated bacteria were largely responsible for the final phase of the fermentation. The bacteria were phylogenetically related to Lactobacillus acidophilus and Lactobacillus delbrueckii, and strains similar to the former had previously been recovered from malt whisky fermentations in Japan. These were probably obligately homofermentative bacteria, required malt wort for growth, and could not be cultured on normal laboratory media, such as MRS. Their metabolism during the last 20 to 30 h of fermentation was associated with yeast death and autolysis and further accumulation of lactate but no additional acetate. PMID:11772639

  14. Improvement of the antifungal activity of lactic acid bacteria by addition to the growth medium of phenylpyruvic acid, a precursor of phenyllactic acid.

    PubMed

    Valerio, Francesca; Di Biase, Mariaelena; Lattanzio, Veronica M T; Lavermicocca, Paola

    2016-04-02

    The aim of the current study was to improve the antifungal activity of eight lactic acid bacterial (LAB) strains by the addition of phenylpyruvic acid (PPA), a precursor of the antifungal compound phenyllactic acid (PLA), to a defined growth medium (DM). The effect of PPA addition on the LABs antifungal activity related to the production of organic acids (PLA, d-lactic, l-lactic, acetic, citric, formic and 4-hydroxy-phenyllactic acids) and of other phenylpyruvic-derived molecules, was investigated. In the presence of PPA the inhibitory activity (expressed as growth inhibition percentage) against fungal bread contaminants Aspergillus niger and Penicillium roqueforti significantly increased and was, even if not completely, associated to PLA increase (from a mean value of 0.44 to 0.93 mM). While the inhibitory activity against Endomyces fibuliger was mainly correlated to the low pH and to lactic, acetic and p-OH-PLA acids. When the PCA analysis based on data of growth inhibition percentage and organic acid concentrations was performed, strains grown in DM+PPA separated from those grown in DM and the most active strains Lactobacillus plantarum 21B, Lactobacillus fermentum 18B and Lactobacillus brevis 18F grouped together. The antifungal activity resulted to be strain-related, based on a different mechanism of action for filamentous fungi and the yeast and was not exclusively associated to the increase of PLA. Therefore, a further investigation on the unique unidentified peak in HPLC-UV chromatograms, was performed by LC-MS/MS analysis. Actually, full scan mass spectra (negative ion mode) recorded at the retention time of the unknown compound, showed a main peak of m/z 291.0 which was consistent with the nominal mass of the molecular ion [M-H](-) of polyporic acid, a PPA derivative whose antifungal activity has been previously reported (Brewer et al., 1977). In conclusion, the addition of PPA to the growth medium contributed to improve the antifungal activity of LAB

  15. Potential of lactic acid bacteria in aflatoxin risk mitigation.

    PubMed

    Ahlberg, Sara H; Joutsjoki, Vesa; Korhonen, Hannu J

    2015-08-17

    Aflatoxins (AF) are ubiquitous mycotoxins contaminating food and feed. Consumption of contaminated food and feed can cause a severe health risk to humans and animals. A novel biological method could reduce the health risks of aflatoxins through inhibiting mold growth and binding aflatoxins. Lactic acid bacteria (LAB) are commonly used in fermented food production. LAB are known to inhibit mold growth and, to some extent, to bind aflatoxins in different matrices. Reduced mold growth and aflatoxin production may be caused by competition for nutrients between bacterial cells and fungi. Most likely, binding of aflatoxins depends on environmental conditions and is strain-specific. Killed bacteria cells possess consistently better binding abilities for aflatoxin B1 (AFB1) than viable cells. Lactobacilli especially are relatively well studied and provide noticeable possibilities in binding of aflatoxin B1 and M1 in food. It seems that binding is reversible and that bound aflatoxins are released later on (Haskard et al., 2001; Peltonen et al., 2001). This literature review suggests that novel biological methods, such as lactic acid bacteria, show potential in mitigating toxic effects of aflatoxins in food and feed.

  16. A solid form of ambazone with lactic acid

    NASA Astrophysics Data System (ADS)

    Borodi, Gh.; Muresan-Pop, M.; Kacsó, I.; Bratu, I.

    2012-02-01

    In recent years, much research has been carried out on the preparation of pharmaceutical solid forms due to their improved physical-chemical parameters such as solubility, dissolution rate of the drug, chemical stability, melting point and hygroscopic parameter. The aim of this study was to obtain and to investigate the structural properties of the ambazone (AMB) with lactic acid (LA) solid form. The solid form was obtained starting from the mixture of ambazone with lactic acid (1:1), by grinding method at constant temperature. The obtained compound was investigated via X-ray powder diffraction (PXRD), thermal analysis (DSC, TG-DTA) and infrared (FTIR) spectroscopy. The difference between the patterns of AMB•LA and of the starting compounds evidenced a new compound. Using X-ray powder diffraction method, by indexing procedure the unit cell and the lattice parameters were determined. Thermal and FTIR measurements on the pure compounds and on the (1:1) ground mixture of AMB with LA confirm the new salt form formation.

  17. Engineering a Cyanobacterial Cell Factory for Production of Lactic Acid

    PubMed Central

    Angermayr, S. Andreas; Paszota, Michal

    2012-01-01

    Metabolic engineering of microorganisms has become a versatile tool to facilitate production of bulk chemicals, fuels, etc. Accordingly, CO2 has been exploited via cyanobacterial metabolism as a sustainable carbon source of biofuel and bioplastic precursors. Here we extended these observations by showing that integration of an ldh gene from Bacillus subtilis (encoding an l-lactate dehydrogenase) into the genome of Synechocystis sp. strain PCC6803 leads to l-lactic acid production, a phenotype which is shown to be stable for prolonged batch culturing. Coexpression of a heterologous soluble transhydrogenase leads to an even higher lactate production rate and yield (lactic acid accumulating up to a several-millimolar concentration in the extracellular medium) than those for the single ldh mutant. The expression of a transhydrogenase alone, however, appears to be harmful to the cells, and a mutant carrying such a gene is rapidly outcompeted by a revertant(s) with a wild-type growth phenotype. Furthermore, our results indicate that the introduction of a lactate dehydrogenase rescues this phenotype by preventing the reversion. PMID:22865063

  18. Engineering a cyanobacterial cell factory for production of lactic acid.

    PubMed

    Angermayr, S Andreas; Paszota, Michal; Hellingwerf, Klaas J

    2012-10-01

    Metabolic engineering of microorganisms has become a versatile tool to facilitate production of bulk chemicals, fuels, etc. Accordingly, CO(2) has been exploited via cyanobacterial metabolism as a sustainable carbon source of biofuel and bioplastic precursors. Here we extended these observations by showing that integration of an ldh gene from Bacillus subtilis (encoding an l-lactate dehydrogenase) into the genome of Synechocystis sp. strain PCC6803 leads to l-lactic acid production, a phenotype which is shown to be stable for prolonged batch culturing. Coexpression of a heterologous soluble transhydrogenase leads to an even higher lactate production rate and yield (lactic acid accumulating up to a several-millimolar concentration in the extracellular medium) than those for the single ldh mutant. The expression of a transhydrogenase alone, however, appears to be harmful to the cells, and a mutant carrying such a gene is rapidly outcompeted by a revertant(s) with a wild-type growth phenotype. Furthermore, our results indicate that the introduction of a lactate dehydrogenase rescues this phenotype by preventing the reversion.

  19. Identification of lactic acid bacteria isolated from corn stovers.

    PubMed

    Pang, Huili; Zhang, Meng; Qin, Guangyong; Tan, Zhongfang; Li, Zongwei; Wang, Yanping; Cai, Yimin

    2011-10-01

    One hundred and twenty-six strains were isolated from corn stover in Henan Province, China, of which 105 isolates were considered to be lactic acid bacteria (LAB) according to Gram-positive, catalase-negative and mainly metabolic lactic acid product. Analysis of the 16S ribosomal DNA sequence of 21 representative strains was used to confirm the presence of the predominant groups and to determine the phylogenetic affiliation of isolates. The sequences from the various LAB isolates showed high degrees of similarity to those of the GenBank type strains between 99.4% and 100%. The prevalent LAB, predominantly Lactobacillus (85.6%), consisted of L. plantarum (33.3%), L. pentosus (28.6%) and L. brevis (23.7%). Other LAB species as Leuconostoc lactis (4.8%), Weissella cibaria (4.8%) and Enterococcus mundtii (4.8%) also presented in corn stover. The present study is the first to fully document corn stover-associated LAB involved in the silage fermentation. The identification results revealed LAB composition inhabiting corn stover and enabling the future design of appropriate inoculants aimed at improving the fermentation quality of silage.

  20. Naturally Occurring Lactic Acid Bacteria Isolated from Tomato Pomace Silage

    PubMed Central

    Wu, Jing-jing; Du, Rui-ping; Gao, Min; Sui, Yao-qiang; Xiu, Lei; Wang, Xiao

    2014-01-01

    Silage making has become a significant method of forage conservation worldwide. To determine how tomato pomace (TP) may be used effectively as animal feed, it was ensilaged for 90 days and microbiology counts, fermentation characteristics and chemical composition of tomato pomace silage (TPS) were evaluated at the 30th, 60th, and 90th days, respectively. In addition, 103 lactic acid bacteria were isolated from TPS. Based on the phenotypic and chemotaxonomic characteristics, 16S rDNA sequence and carbohydrate fermentation tests, the isolates were identified as 17 species namely: Lactobacillus coryniformis subsp. torquens (0.97%), Lactobacillus pontis (0.97%), Lactobacillus hilgardii (0.97%), Lactobacillus pantheris (0.97%), Lactobacillus amylovorus (1.9%), Lactobacillus panis (1.9%), Lactobacillus vaginalis (1.9%), Lactobacillus rapi (1.9%), Lactobacillus buchneri (2.9%), Lactobacillus parafarraginis (2.9%), Lactobacillus helveticus (3.9%), Lactobacillus camelliae (3.9%), Lactobacillus fermentum (5.8%), Lactobacillus manihotivorans (6.8%), Lactobacillus plantarum (10.7%), Lactobacillus harbinensis (16.5%) and Lactobacillus paracasei subsp. paracasei (35.0%). This study has shown that TP can be well preserved for 90 days by ensilaging and that TPS is not only rich in essential nutrients, but that physiological and biochemical properties of the isolates could provide a platform for future design of lactic acid bacteria (LAB) inoculants aimed at improving the fermentation quality of silage. PMID:25049999

  1. Failure of polymerized lactic acid tacks in shoulder surgery.

    PubMed

    Wilkerson, John P; Zvijac, John E; Uribe, John W; Schürhoff, Matthias R; Green, Jeremy B

    2003-01-01

    The purpose of this study was to evaluate 4 cases in which bioabsorbable polymerized lactic acid tacks failed after arthroscopic shoulder surgery. Four male elite athletes with recurrent shoulder pain were seen a mean of 7.5 months (range, 3-10 months) after initial arthroscopy. Three of the cases involved superior labrum anterior-to-posterior (SLAP) lesion stabilization, and the fourth case was a rotator cuff (RTC) repair. In the three labral repairs, the implant had broken and the unabsorbed fragments were visible with magnetic resonance imaging. The device used in the RTC repair showed no signs of absorption. All 4 patients underwent arthroscopic removal of the polymer tack fragments to alleviate their symptoms, 2 of whom had foreign-body reactions that required synovectomy. On the basis of clinical examination and magnetic resonance imaging, 2 of the SLAP lesions and the RTC tear had healed. The third patient with a SLAP lesion required arthroscopic debridement of a portion of the labrum. The intact RTC implant had backed out of its insertion point. In all 3 labral repairs, the polymerized lactic acid implant experienced a mechanical failure near the head-shaft junction. We theorize that the labral implants failed because of the variable rate of degradation along the shaft of the devices from the intraarticular to intraosseous regions.

  2. Acetic acid removal from corn stover hydrolysate using ethyl acetate and the impact on Saccharomyces cerevisiae bioethanol fermentation.

    PubMed

    Aghazadeh, Mahdieh; Ladisch, Michael R; Engelberth, Abigail S

    2016-07-08

    Acetic acid is introduced into cellulose conversion processes as a consequence of composition of lignocellulose feedstocks, causing significant inhibition of adapted, genetically modified and wild-type S. cerevisiae in bioethanol fermentation. While adaptation or modification of yeast may reduce inhibition, the most effective approach is to remove the acetic acid prior to fermentation. This work addresses liquid-liquid extraction of acetic acid from biomass hydrolysate through a pathway that mitigates acetic acid inhibition while avoiding the negative effects of the extractant, which itself may exhibit inhibition. Candidate solvents were selected using simulation results from Aspen Plus™, based on their ability to extract acetic acid which was confirmed by experimentation. All solvents showed varying degrees of toxicity toward yeast, but the relative volatility of ethyl acetate enabled its use as simple vacuum evaporation could reduce small concentrations of aqueous ethyl acetate to minimally inhibitory levels. The toxicity threshold of ethyl acetate, in the presence of acetic acid, was found to be 10 g L(-1) . The fermentation was enhanced by extracting 90% of the acetic acid using ethyl acetate, followed by vacuum evaporation to remove 88% removal of residual ethyl acetate along with 10% of the broth. NRRL Y-1546 yeast was used to demonstrate a 13% increase in concentration, 14% in ethanol specific production rate, and 11% ethanol yield. This study demonstrated that extraction of acetic acid with ethyl acetate followed by evaporative removal of ethyl acetate from the raffinate phase has potential to significantly enhance ethanol fermentation in a corn stover bioethanol facility. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:929-937, 2016.

  3. Photodissociation spectroscopy of the Mg{sup +}-acetic acid complex

    SciTech Connect

    Abate, Yohannes; Kleiber, P. D.

    2006-11-14

    We have studied the structure and photodissociation of Mg{sup +}-acetic acid clusters. Ab initio calculations suggest four relatively strongly bound ground state isomers for the [MgC{sub 2}H{sub 4}O{sub 2}]{sup +} complex. These isomers include the cis and trans forms of the Mg{sup +}-acetic acid association complex with Mg{sup +} bonded to the carbonyl O atom of acetic acid, the Mg{sup +}-acetic acid association complex with Mg{sup +} bonded to the hydroxyl O atom of acetic acid, or to a Mg{sup +}-ethenediol association complex. Photodissociation through the Mg{sup +}-based 3p<-3s absorption bands in the near UV leads to direct (nonreactive) and reactive dissociation products: Mg{sup +}, MgOH{sup +}, Mg(H{sub 2}O){sup +}, CH{sub 3}CO{sup +}, and MgCH{sub 3}{sup +}. At low energies the dominant reactive quenching pathway is through dehydration to Mg(H{sub 2}O){sup +}, but additional reaction channels involving C-H and C-C bond activation are also open at higher energies.

  4. Simultaneous acetic acid separation and monosaccharide concentration by reverse osmosis.

    PubMed

    Zhou, Fanglei; Wang, Cunwen; Wei, Jiang

    2013-03-01

    This study aimed to investigate the feasibility and efficiency of simultaneous acetic acid separation and sugar concentration in model lignocellulosic hydrolyzates by reverse osmosis. The effects of operation parameters such as pH, temperature, pressure and feed concentration on the solute retentions were examined with a synthetic xylose–glucose–acetic acid model solution. Results showed that the monosaccharides were almost completely rejected at above 20 bar, while the acetic acid retention increased with the increase in pH and pressure, and decreased with the temperature increase. The maximum separation factors of acetic acid over xylose and glucose reached as high as 211.5 and 228.4 at pH 2.93 (the initial pH of model lignocellulosic hydrolyzates), 40 °C and 20 bar. Furthermore, the concentration and diafiltration process were employed at optimal operation conditions. Consequently, a high sugar concentration and a beneficially lower acetic acid concentration were simultaneously achieved by reverse osmosis.

  5. Plasma D-lactic acid level: a useful marker to distinguish perforated from acute simple appendicitis.

    PubMed

    Demircan, Mehmet; Cetin, Selma; Uguralp, Sema; Sezgin, Nurzen; Karaman, Abdurrahman; Gozukara, Engin M

    2004-10-01

    Early diagnosis of perforated appendicitis is important for reducing morbidity rates. The aim of this study was to determine the value and utility of plasma D-lactic acid levels in identifying the type of appendicitis. In this clinical study, plasma D-lactic acid levels were assessed in 44 consecutive paediatric patients (23 with acute appendicitis, 21 with perforated appendicitis) before laparotomy. D-lactic acid levels were determined by an enzymatic spectrophotometric technique using a D-lactic acid dehydrogenase kit. Patients with perforated appendicitis had higher D-lactic acid levels (3.970 +/- 0.687 mg/dL) than patients in the control group (0.478 +/- 0.149 mg/dL) and patients with acute appendicitis (1.409 +/- 0.324 mg/dL; p < 0.05). For a plasma D-lactic acid level greater than 2.5 mg/dL, the sensitivity and specificity of the D-lactic acid assay were 96% and 87%, respectively. The positive predictive value was 87%, the negative predictive value was 96%, and the diagnostic value was 91%. These results suggest that the measurement of plasma D-lactic acid levels may be a useful adjunct to clinical and radiological findings in distinguishing perforated from acute non-perforated appendicitis in children.

  6. Capillary electrophoresis as a tool for evaluating lactic acid production from sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Interest in the use of renewable resources for the production of bio-industrial chemicals and fuels is increasing. One industrial chemical that can be produced from renewable resources is lactic acid. Lactic acid is used in the food industry as a flavor compound, preservative, and to acidify produ...

  7. Efficient production of L-lactic acid from xylose by a recombinant Candida utilis strain.

    PubMed

    Tamakawa, Hideyuki; Ikushima, Shigehito; Yoshida, Satoshi

    2012-01-01

    Efficient L-lactic acid production from xylose was achieved using a pyruvate decarboxylase-deficient Candida utilis strain expressing an L-lactate dehydrogenase, an NADH-preferring mutated xylose reductase (XR), a xylitol dehydrogenase and a xylulokinase. The recombinant strain showed 53% increased L-lactic acid production compared with the reference strain expressing native XR (NADPH-preferring).

  8. Production of lactic acid using a new homofermentative Enterococcus faecalis isolate.

    PubMed

    Subramanian, Mohan Raj; Talluri, Suvarna; Christopher, Lew P

    2015-03-01

    Lactic acid is an intermediate-volume specialty chemical for a wide range of food and industrial applications such as pharmaceuticals, cosmetics and chemical syntheses. Although lactic acid production has been well documented, improved production parameters that lead to reduced production costs are always of interest in industrial developments. In this study, we describe the production of lactic acid at high concentration, yield and volumetric productivity utilizing a novel homofermentative, facultative anaerobe Enterococcus faecalis CBRD01. The highest concentration of 182 g lactic acid l(-1) was achieved after 38 h of fed-batch fermentation on glucose. The bacterial isolate utilized only 2-13% of carbon for its growth and energy metabolism, while 87-98% of carbon was converted to lactic acid at an overall volumetric productivity of 5 g l(-1)  h(-1). At 13 h of fermentation, the volumetric productivity of lactate production reached 10.3 g l(-1)  h(-1), which is the highest ever reported for microbial production of lactic acid. The lactic acid produced was of high purity as formation of other metabolites was less than 0.1%. The present investigation demonstrates a new opportunity for enhanced production of lactic acid with potential for reduced purification costs.

  9. Synthesis and characterization of poly(lactic acid-co-glycolic acid) complex microspheres as drug carriers.

    PubMed

    Wang, Fang; Liu, Xiuxiu; Yuan, Jian; Yang, Siqian; Li, Yueqin; Gao, Qinwei

    2016-10-01

    Poly(lactic-co-glycolic) acid (PLGA) is synthesized via melt polycondensation directly from lactic acid and glycolic acid with a feed molar ratio of 75/25. Bovine serum albumin, which is used as model protein, is entrapped into the poly(lactic-co-glycolic acid) microspheres with particle size of 260.9 ± 20.0 nm by the double emulsification method. Then it is the first report of producing more carboxyl groups by poly(lactic-co-glycolic acid) surface hydrolysis. The purpose is developing poly(lactic-co-glycolic acid) microspheres surface, which is modified with chitosan by chemical reaction between carboxyl groups and amine groups. The particle size and the positive zeta potential of the poly(lactic-co-glycolic acid)/chitosan microspheres are 388.2 ± 35.6 nm and 10.4 ± 2.9 mV, respectively. The drug loading ratio and encapsulation efficacy of poly(lactic-co-glycolic acid)/chitosan microspheres are 36.3% and 57.5%, which are higher than PLGA microspheres. Furthermore, the drug burst release of poly(lactic-co-glycolic acid)/chitosan microspheres at 10 h is decreased to 21.72% while the corresponding value of the poly(lactic-co-glycolic acid) microsphere is 64.56%. These results reveal that surface hydrolysis modification of poly(lactic-co-glycolic acid) is an efficient method to improve the negative potential and chemical reaction properties of the polymer. And furthermore, this study shows that chitosan-modified poly(lactic-co-glycolic acid) microspheres is a promising system for the controlled release of pharmaceutical proteins.

  10. Production of lactic acid and fungal biomass by Rhizopus fungi from food processing waste streams.

    PubMed

    Jin, Bo; Yin, Pinghe; Ma, Yihong; Zhao, Ling

    2005-12-01

    This study proposed a novel waste utilization bioprocess for production of lactic acid and fungal biomass from waste streams by fungal species of Rhizopus arrhizus 36017 and R. oryzae 2062. The lactic acid and fungal biomass were produced in a single-stage simultaneous saccharification and fermentation process using potato, corn, wheat and pineapple waste streams as production media. R. arrhizus 36017 gave a high lactic acid yield up to 0.94-0.97 g/g of starch or sugars associated with 4-5 g/l of fungal biomass produced, while 17-19 g/l fungal biomass with a lactic acid yield of 0.65-0.76 g/g was produced by the R. oryzae 2062 in 36-48 h fermentation. Supplementation of 2 g/l of ammonium sulfate, yeast extract and peptone stimulated an increase in 8-15% lactic acid yield and 10-20% fungal biomass.

  11. Semicontinuous Production of Lactic Acid From Cheese Whey Using Integrated Membrane Reactor

    NASA Astrophysics Data System (ADS)

    Li, Yebo; Shahbazi, Abolghasem; Coulibaly, Sekou; Mims, Michele M.

    Semicontinuous production of lactic acid from cheese whey using free cells of Bifidobacterium longum with and without nanofiltration was studied. For the semicontinuous fermentation without membrane separation, the lactic acid productivity of the second and third runs is much lower than the first run. The semicontinuous fermentation with nanoseparation was run semicontinuously for 72 h with lactic acid to be harvested every 24 h using a nanofiltration membrane unit. The cells and unutilized lactose were kept in the reactor and mixed with newly added cheese whey in the subsequent runs. Slight increase in the lactic acid productivity was observed in the second and third runs during the semicontinuous fermentation with nanofiltration. It can be concluded that nanoseparation could improve the lactic acid productivity of the semicontinuous fermentation process.

  12. Reactive Extraction of Lactic Acid by Using Tri-n-octylamine: Structure of the Ionic Phase.

    PubMed

    Aimer, Matthias; Klemm, Elias; Langanke, Bernd; Gehrke, Helmut; Stubenrauch, Cosima

    2016-03-01

    Lactic acid is a promising biogenic platform chemical which can be produced by fermentation of cellulose and hemicellulose. However, separating lactic acid from the fermentation broth is extremely costly and technically complex. We therefore investigated whether liquid/liquid extraction of lactic acid with tri-n-octylamine is a cost-effective alternative to the existing downstream processing method. In order to find an answer to this question, the structure of the middle phase of the occurring three-phase region, which is enriched with up to 20 wt. % lactic acid, was explored. The results of our IR, small-angle X-ray scattering and NMR measurements show that this phase is ionic and has a bicontinuous structure. Due to the analogy with bicontinuous microemulsions, it should be possible to further enrich the lactic acid, which could lead to a rethink regarding the design of extraction processes.

  13. Betaine and beet molasses enhance L-lactic acid production by Bacillus coagulans.

    PubMed

    Xu, Ke; Xu, Ping

    2014-01-01

    Lactic acid is an important chemical with various industrial applications, and it can be efficiently produced by fermentation, in which Bacillus coagulans strains present excellent performance. Betaine can promote lactic acid fermentation as an effective osmoprotectant. Here, positive effect of betaine on fermentation by B. coagulans is revealed. Betaine could enhance lactic acid production by protecting l-LDH activity and cell growth from osmotic inhibition, especially under high glucose concentrations and with poor organic nitrogen nutrients. The fermentation with 0.05 g/L betaine could produce 17.9% more lactic acid compared to the fermentation without betaine. Beet molasses, which is rich in sucrose and betaine, was utilized in a co-feeding fermentation and raised the productivity by 22%. The efficient lactic acid fermentation by B. coagulans is thus developed by using betaine and beet molasses.

  14. Chirality Matters: Synthesis and Consumption of the d-Enantiomer of Lactic Acid by Synechocystis sp. Strain PCC6803.

    PubMed

    Angermayr, S Andreas; van der Woude, Aniek D; Correddu, Danilo; Kern, Ramona; Hagemann, Martin; Hellingwerf, Klaas J

    2015-12-18

    Both enantiomers of lactic acid, l-lactic acid and d-lactic acid, can be produced in a sustainable way by a photosynthetic microbial cell factory and thus from CO2, sunlight, and water. Several properties of polylactic acid (a polyester of polymerized lactic acid) depend on the controlled blend of these two enantiomers. Recently, cyanobacterium Synechocystis sp. strain PCC6803 was genetically modified to allow formation of either of these two enantiomers. This report elaborates on the d-lactic acid production achieved by the introduction of a d-specific lactate dehydrogenase from the lactic acid bacterium Leuconostoc mesenteroides into Synechocystis. A typical batch culture of this recombinant strain initially shows lactic acid production, followed by a phase of lactic acid consumption, until production "outcompetes" consumption at later growth stages. We show that Synechocystis is able to use d-lactic acid, but not l-lactic acid, as a carbon source for growth. Deletion of the organism's putative d-lactate dehydrogenase (encoded by slr1556), however, does not eliminate this ability with respect to d-lactic acid consumption. In contrast, d-lactic acid consumption does depend on the presence of glycolate dehydrogenase GlcD1 (encoded by sll0404). Accordingly, this report highlights the need to match a product of interest of a cyanobacterial cell factory with the metabolic network present in the host used for its synthesis and emphasizes the need to understand the physiology of the production host in detail.

  15. Chirality Matters: Synthesis and Consumption of the d-Enantiomer of Lactic Acid by Synechocystis sp. Strain PCC6803

    PubMed Central

    Angermayr, S. Andreas; Correddu, Danilo; Kern, Ramona; Hagemann, Martin; Hellingwerf, Klaas J.

    2015-01-01

    Both enantiomers of lactic acid, l-lactic acid and d-lactic acid, can be produced in a sustainable way by a photosynthetic microbial cell factory and thus from CO2, sunlight, and water. Several properties of polylactic acid (a polyester of polymerized lactic acid) depend on the controlled blend of these two enantiomers. Recently, cyanobacterium Synechocystis sp. strain PCC6803 was genetically modified to allow formation of either of these two enantiomers. This report elaborates on the d-lactic acid production achieved by the introduction of a d-specific lactate dehydrogenase from the lactic acid bacterium Leuconostoc mesenteroides into Synechocystis. A typical batch culture of this recombinant strain initially shows lactic acid production, followed by a phase of lactic acid consumption, until production “outcompetes” consumption at later growth stages. We show that Synechocystis is able to use d-lactic acid, but not l-lactic acid, as a carbon source for growth. Deletion of the organism's putative d-lactate dehydrogenase (encoded by slr1556), however, does not eliminate this ability with respect to d-lactic acid consumption. In contrast, d-lactic acid consumption does depend on the presence of glycolate dehydrogenase GlcD1 (encoded by sll0404). Accordingly, this report highlights the need to match a product of interest of a cyanobacterial cell factory with the metabolic network present in the host used for its synthesis and emphasizes the need to understand the physiology of the production host in detail. PMID:26682849

  16. Characterization of acetic acid bacteria in "traditional balsamic vinegar".

    PubMed

    Gullo, Maria; Caggia, Cinzia; De Vero, Luciana; Giudici, Paolo

    2006-02-01

    This study evaluated the glucose tolerance of acetic acid bacteria strains isolated from Traditional Balsamic Vinegar. The results showed that the greatest hurdle to acetic acid bacteria growth is the high sugar concentration, since the majority of the isolated strains are inhibited by 25% of glucose. Sugar tolerance is an important technological trait because Traditional Balsamic Vinegar is made with concentrated cooked must. On the contrary, ethanol concentration of the cooked and fermented must is less significant for acetic acid bacteria growth. A tentative identification of the isolated strains was done by 16S-23S-5S rDNA PCR/RFLP technique and the isolated strains were clustered: 32 strains belong to Gluconacetobacter xylinus group, two strains to Acetobacter pasteurianus group and one to Acetobacter aceti.

  17. Metabolic strategies of beer spoilage lactic acid bacteria in beer.

    PubMed

    Geissler, Andreas J; Behr, Jürgen; von Kamp, Kristina; Vogel, Rudi F

    2016-01-04

    Beer contains only limited amounts of readily fermentable carbohydrates and amino acids. Beer spoilage lactic acid bacteria (LAB) have to come up with metabolic strategies in order to deal with selective nutrient content, high energy demand of hop tolerance mechanisms and a low pH. The metabolism of 26 LAB strains of 6 species and varying spoilage potentialwas investigated in order to define and compare their metabolic capabilities using multivariate statistics and outline possible metabolic strategies. Metabolic capabilities of beer spoilage LAB regarding carbohydrate and amino acids did not correlate with spoilage potential, but with fermentation type (heterofermentative/homofermentative) and species. A shift to mixed acid fermentation by homofermentative (hof) Pediococcus claussenii and Lactobacillus backii was observed as a specific feature of their growth in beer. For heterofermentative (hef) LAB a mostly versatile carbohydrate metabolism could be demonstrated, supplementing the known relevance of organic acids for their growth in beer. For hef LAB a distinct amino acid metabolism, resulting in biogenic amine production, was observed, presumably contributing to energy supply and pH homeostasis.

  18. Fermentation of aqueous plant seed extracts by lactic acid bacteria

    SciTech Connect

    Schafner, D.W.; Beuchat, R.L.

    1986-05-01

    The effects of lactic acid bacterial fermentation on chemical and physical changes in aqueous extracts of cowpea (Vigna unguiculata), peanut (Arachis hypogea), soybean (Glycine max), and sorghum (Sorghum vulgare) were studied. The bacteria investigated were Lactobacillus helveticus, L. delbrueckii, L. casei, L. bulgaricus, L. acidophilus, and Streptococcus thermophilus. Organisms were inoculated individually into all of the seed extracts; L. bulgaricus and S. thermophilus were also evaluated together as inocula for fermenting the legume extracts. During fermentation, bacterial population and changes in titratable acidity, pH, viscosity, and color were measured over a 72 h period at 37 degrees C. Maximum bacterial populations, titratable acidity, pH, and viscosity varied depending upon the type of extract and bacterial strain. The maximum population of each organism was influenced by fermentable carbohydrates, which, in turn, influenced acid production and change in pH. Change in viscosity was correlated with the amount of protein and titratable acidity of products. Color was affected by pasteurization treatment and fermentation as well as the source of extract. In the extracts inoculated simultaneously with L. bulgaricus and S. thermophilus, a synergistic effect resulted in increased bacterial populations, titratable acidity, and viscosity, and decreased pH in all the legume extracts when compared to the extracts fermented with either of these organisms individually. Fermented extracts offer potential as substitutes for cultured dairy products. 24 references.

  19. Catalysis of the Carbonylation of Alcohols to Carboxylic Acids Including Acetic Acid Synthesis from Methanol.

    ERIC Educational Resources Information Center

    Forster, Denis; DeKleva, Thomas W.

    1986-01-01

    Monsanto's highly successful synthesis of acetic acid from methanol and carbon monoxide illustrates use of new starting materials to replace pretroleum-derived ethylene. Outlines the fundamental aspects of the acetic acid process and suggests ways of extending the synthesis to higher carboxylic acids. (JN)

  20. M2-like macrophage polarization in high lactic acid-producing head and neck cancer.

    PubMed

    Ohashi, Toshimitsu; Aoki, Mitsuhiro; Tomita, Hiroyuki; Akazawa, Takashi; Sato, Katsuya; Kuze, Bunya; Mizuta, Keisuke; Hara, Akira; Nagaoka, Hitoshi; Inoue, Norimitsu; Ito, Yatsuji

    2017-04-01

    Reprogramming of glucose metabolism in tumor cells is referred to as the Warburg effect and results in increased lactic acid secretion into the tumor microenvironment. We have previously shown that lactic acid has important roles as a proinflammatory and immunosuppressive mediator and promotes tumor progression. In this study, we examined the relationship between the lactic acid concentration and expression of lactate dehydrogenase-A (LDHA) and glucose transporter-1 (GLUT1), which are related to the Warburg effect, in human head and neck squamous cell carcinoma (HNSCC). Tumors expressing lower levels of LDHA and GLUT1 had a higher concentration of lactic acid than those with higher LDHA and GLUT1 expression. Lactic acid also suppressed the expression of LDHA and GLUT1 in vitro. We previously reported that lactic acid enhances expression of a M2 macrophage marker, arginase I (ARG1), in murine macrophages. Therefore, we investigated the relationship between the lactic acid concentration and polarization of M2 macrophages in HNSCC by measuring the expression of M2 macrophage markers, colony stimulating factor 1 receptor (CSF1R) and CD163, normalized using a pan-macrophage marker, CD68. Tumors with lower levels of CD68 showed a higher concentration of lactic acid, while those with higher levels of CSF1R showed a significantly higher concentration of lactic acid. A similar tendency was observed for CD163. These results suggest that tumor-secreted lactic acid is linked to the reduction of macrophages in tumors and promotes induction of M2-like macrophage polarization in human HNSCC. This article is protected by copyright. All rights reserved.

  1. Genomic reconstruction of transcriptional regulatory networks in lactic acid bacteria

    PubMed Central

    2013-01-01

    Background Genome scale annotation of regulatory interactions and reconstruction of regulatory networks are the crucial problems in bacterial genomics. The Lactobacillales order of bacteria collates various microorganisms having a large economic impact, including both human and animal pathogens and strains used in the food industry. Nonetheless, no systematic genome-wide analysis of transcriptional regulation has been previously made for this taxonomic group. Results A comparative genomics approach was used for reconstruction of transcriptional regulatory networks in 30 selected genomes of lactic acid bacteria. The inferred networks comprise regulons for 102 orthologous transcription factors (TFs), including 47 novel regulons for previously uncharacterized TFs. Numerous differences between regulatory networks of the Streptococcaceae and Lactobacillaceae groups were described on several levels. The two groups are characterized by substantially different sets of TFs encoded in their genomes. Content of the inferred regulons and structure of their cognate TF binding motifs differ for many orthologous TFs between the two groups. Multiple cases of non-orthologous displacements of TFs that control specific metabolic pathways were reported. Conclusions The reconstructed regulatory networks substantially expand the existing knowledge of transcriptional regulation in lactic acid bacteria. In each of 30 studied genomes the obtained regulatory network contains on average 36 TFs and 250 target genes that are mostly involved in carbohydrate metabolism, stress response, metal homeostasis and amino acids biosynthesis. The inferred networks can be used for genetic experiments, functional annotations of genes, metabolic reconstruction and evolutionary analysis. All reconstructed regulons are captured within the Streptococcaceae and Lactobacillaceae collections in the RegPrecise database (http://regprecise.lbl.gov). PMID:23398941

  2. Lactic acid and exercise performance : culprit or friend?

    PubMed

    Cairns, Simeon P

    2006-01-01

    This article critically discusses whether accumulation of lactic acid, or in reality lactate and/or hydrogen (H+) ions, is a major cause of skeletal muscle fatigue, i.e. decline of muscle force or power output leading to impaired exercise performance. There exists a long history of studies on the effects of increased lactate/H+ concentrations in muscle or plasma on contractile performance of skeletal muscle. Evidence suggesting that lactate/H+ is a culprit has been based on correlation-type studies, which reveal close temporal relationships between intramuscular lactate or H+ accumulation and the decline of force during fatiguing stimulation in frog, rodent or human muscle. In addition, an induced acidosis can impair muscle contractility in non-fatigued humans or in isolated muscle preparations, and several mechanisms to explain such effects have been provided. However, a number of recent high-profile papers have seriously challenged the 'lactic acid hypothesis'. In the 1990s, these findings mainly involved diminished negative effects of an induced acidosis in skinned or intact muscle fibres, at higher more physiological experimental temperatures. In the early 2000s, it was conclusively shown that lactate has little detrimental effect on mechanically skinned fibres activated by artificial stimulation. Perhaps more remarkably, there are now several reports of protective effects of lactate exposure or induced acidosis on potassium-depressed muscle contractions in isolated rodent muscles. In addition, sodium-lactate exposure can attenuate severe fatigue in rat muscle stimulated in situ, and sodium lactate ingestion can increase time to exhaustion during sprinting in humans. Taken together, these latest findings have led to the idea that lactate/H+ is ergogenic during exercise. It should not be taken as fact that lactic acid is the deviant that impairs exercise performance. Experiments on isolated muscle suggest that acidosis has little detrimental effect or may even

  3. 21 CFR 862.1390 - 5-Hydroxyindole acetic acid/serotonin test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false 5-Hydroxyindole acetic acid/serotonin test system... Test Systems § 862.1390 5-Hydroxyindole acetic acid/serotonin test system. (a) Identification. A 5-hydroxyindole acetic acid/serotonin test system is a device intended to measure 5-hydroxyindole acetic...

  4. 21 CFR 862.1390 - 5-Hydroxyindole acetic acid/serotonin test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false 5-Hydroxyindole acetic acid/serotonin test system... Test Systems § 862.1390 5-Hydroxyindole acetic acid/serotonin test system. (a) Identification. A 5-hydroxyindole acetic acid/serotonin test system is a device intended to measure 5-hydroxyindole acetic...

  5. 21 CFR 862.1390 - 5-Hydroxyindole acetic acid/serotonin test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false 5-Hydroxyindole acetic acid/serotonin test system... Test Systems § 862.1390 5-Hydroxyindole acetic acid/serotonin test system. (a) Identification. A 5-hydroxyindole acetic acid/serotonin test system is a device intended to measure 5-hydroxyindole acetic...

  6. 21 CFR 862.1390 - 5-Hydroxyindole acetic acid/serotonin test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false 5-Hydroxyindole acetic acid/serotonin test system... Test Systems § 862.1390 5-Hydroxyindole acetic acid/serotonin test system. (a) Identification. A 5-hydroxyindole acetic acid/serotonin test system is a device intended to measure 5-hydroxyindole acetic...

  7. Engineering cellular redox balance in Saccharomyces cerevisiae for improved production of L-lactic acid.

    PubMed

    Lee, Ju Young; Kang, Chang Duk; Lee, Seung Hyun; Park, Young Kyoung; Cho, Kwang Myung

    2015-04-01

    Owing to the growing market for the biodegradable and renewable polymer, polylactic acid, world demand for lactic acid is rapidly increasing. However, the very high concentrations desired for industrial production of the free lactic acid create toxicity and low pH concerns for manufacturers. Saccharomyces cerevisiae is the most well characterized eukaryote, a preferred microbial cell factory for the largest industrial biotechnology product (bioethanol), and a robust, commercially compatible workhorse to be exploited for the production of diverse chemicals. S. cerevisiae has also been explored as a host for lactic acid production because of its high acid tolerance. Here, we constructed an L-lactic acid-overproducing S. cerevisiae by redirecting cellular metabolic fluxes to the production of L-lactic acid. To this end, we deleted the S. cerevisiae genes encoding pyruvate decarboxylase 1 (PDC1), L-lactate cytochrome-c oxidoreductase (CYB2), and glycerol-3-phosphate dehydrogenase (GPD1), replacing them with a heterologous L-lactate dehydrogenase (LDH) gene. Two new target genes encoding isoenzymes of the external NADH dehydrogenase (NDE1 and NDE2), were also deleted from the genome to re-engineer the intracellular redox balance. The resulting strain was found to produce L-lactic acid more efficiently (32.6% increase in final L-lactic acid titer). When tested in a bioreactor in fed-batch mode, this engineered strain produced 117 g/L of L-lactic acid under low pH conditions. This result demonstrates that the redox balance engineering should be coupled with the metabolic engineering in the construction of L-lactic acid-overproducing S. cerevisiae.

  8. Development of Mucosal Vaccines Based on Lactic Acid Bacteria

    NASA Astrophysics Data System (ADS)

    Bermúdez-Humarán, Luis G.; Innocentin, Silvia; Lefèvre, Francois; Chatel, Jean-Marc; Langella, Philippe

    Today, sufficient data are available to support the use of lactic acid bacteria (LAB), notably lactococci and lactobacilli, as delivery vehicles for the development of new mucosal vaccines. These non-pathogenic Gram-positive bacteria have been safely consumed by humans for centuries in fermented foods. They thus constitute an attractive alternative to the attenuated pathogens (most popular live vectors actually studied) which could recover their pathogenic potential and are thus not totally safe for use in humans. This chapter reviews the current research and advances in the use of LAB as live delivery vectors of proteins of interest for the development of new safe mucosal vaccines. The use of LAB as DNA vaccine vehicles to deliver DNA directly to antigen-presenting cells of the immune system is also discussed.

  9. Lactic acid bacteria as adjuvants for sublingual allergy vaccines.

    PubMed

    Van Overtvelt, Laurence; Moussu, Helene; Horiot, Stéphane; Samson, Sandrine; Lombardi, Vincent; Mascarell, Laurent; van de Moer, Ariane; Bourdet-Sicard, Raphaëlle; Moingeon, Philippe

    2010-04-09

    We compared immunomodulatory properties of 11 strains of lactic acid bacteria as well as their capacity to enhance sublingual immunotherapy efficacy in a murine asthma model. Two types of bacterial strains were identified, including: (i) potent inducers of IL-12p70 and IL-10 in dendritic cells, supporting IFN-gamma and IL-10 production in CD4+ T cells such as Lactobacillus helveticus; (ii) pure Th1 inducers such as L. casei. Sublingual administration in ovalbumin-sensitized mice of L. helveticus, but not L. casei, reduced airways hyperresponsiveness, bronchial inflammation and proliferation of specific T cells in cervical lymph nodes. Thus, probiotics acting as a Th1/possibly Treg, but not Th1 adjuvant, potentiate tolerance induction via the sublingual route.

  10. Application of poly(lactic acid) modified by radiation crosslinking

    NASA Astrophysics Data System (ADS)

    Nagasawa, Naotsugu; Kaneda, Ayako; Kanazawa, Shinichi; Yagi, Toshiaki; Mitomo, Hiroshi; Yoshii, Fumio; Tamada, Masao

    2005-07-01

    Poly(L-lactic acid), PLLA was irradiated using electron beam (EB) in the presence of polyfunctional monomers (PFM) as crosslinking agent. Among the PFMs, triallyl isocyanurate (TAIC) at 3% concentration was found to be the most effective for crosslinking of PLLA by irradiation technique. The crosslinked PLLA obtained has heat resistance higher than 200 °C. From this fact, the crosslinked PLLA is applied on heat-shrinkable tube, cup and plate. The shrinkable tube has several advantages such as high heat resistance and transparency. In addition, the unirradiated cup deformed and changed to milky-like transparency but the crosslinked one retained its original shape and transparency after boiling water was poured into the cups. The heat resistance is attributed to the protection of crystallization of crosslinking structure. It is therefore proven that crosslinking technology is beneficial to expanding the application of PLLA.

  11. Current taxonomy of phages infecting lactic acid bacteria

    PubMed Central

    Mahony, Jennifer; van Sinderen, Douwe

    2013-01-01

    Phages infecting lactic acid bacteria have been the focus of significant research attention over the past three decades. Through the isolation and characterization of hundreds of phage isolates, it has been possible to classify phages of the dairy starter and adjunct bacteria Lactococus lactis, Streptococcus thermophilus, Leuconostoc spp., and Lactobacillus spp. Among these, phages of L. lactis have been most thoroughly scrutinized and serve as an excellent model system to address issues that arise when attempting taxonomic classification of phages infecting other LAB species. Here, we present an overview of the current taxonomy of phages infecting LAB genera of industrial significance, the methods employed in these taxonomic efforts and how these may be employed for the taxonomy of phages of currently underrepresented and emerging phage species. PMID:24478767

  12. Variations in prebiotic oligosaccharide fermentation by intestinal lactic acid bacteria.

    PubMed

    Endo, Akihito; Nakamura, Saki; Konishi, Kenta; Nakagawa, Junichi; Tochio, Takumi

    2016-01-01

    Prebiotic oligosaccharides confer health benefits on the host by modulating the gut microbiota. Intestinal lactic acid bacteria (LAB) are potential targets of prebiotics; however, the metabolism of oligosaccharides by LAB has not been fully characterized. Here, we studied the metabolism of eight oligosaccharides by 19 strains of intestinal LAB. Among the eight oligosaccharides used, 1-kestose, lactosucrose and galactooligosaccharides (GOSs) led to the greatest increases in the numbers of the strains tested. However, mono- and disaccharides accounted for more than half of the GOSs used, and several strains only metabolized the mono- and di-saccharides in GOSs. End product profiles indicated that the amounts of lactate produced were generally consistent with the bacterial growth recorded. Oligosaccharide profiling revealed the interesting metabolic manner in Lactobacillus paracasei strains, which metabolized all oligosaccharides, but left sucrose when cultured with fructooligosaccharides. The present study clearly indicated that the prebiotic potential of each oligosaccharide differs.

  13. Screening and characterization of novel bacteriocins from lactic acid bacteria.

    PubMed

    Zendo, Takeshi

    2013-01-01

    Bacteriocins produced by lactic acid bacteria (LAB) are expected to be safe antimicrobial agents. While the best studied LAB bacteriocin, nisin A, is widely utilized as a food preservative, various novel ones are required to control undesirable bacteria more effectively. To discover novel bacteriocins at the early step of the screening process, we developed a rapid screening system that evaluates bacteriocins produced by newly isolated LAB based on their antibacterial spectra and molecular masses. By means of this system, various novel bacteriocins were identified, including a nisin variant, nisin Q, a two-peptide bacteriocin, lactococcin Q, a leaderless bacteriocin, lacticin Q, and a circular bacteriocin, lactocyclicin Q. Moreover, some LAB isolates were found to produce multiple bacteriocins. They were characterized as to their structures, mechanisms of action, and biosynthetic mechanisms. Novel LAB bacteriocins and their biosynthetic mechanisms are expected for applications such as food preservation and peptide engineering.

  14. Antiviral potential of lactic acid bacteria and their bacteriocins.

    PubMed

    Al Kassaa, I; Hober, D; Hamze, M; Chihib, N E; Drider, D

    2014-12-01

    Emerging resistance to antiviral agents is a growing public health concern worldwide as it was reported for respiratory, sexually transmitted and enteric viruses. Therefore, there is a growing demand for new, unconventional antiviral agents which may serve as an alternative to the currently used drugs. Meanwhile, published literature continues shedding the light on the potency of lactic acid bacteria (LAB) and their bacteriocins as antiviral agents. Health-promoting LAB probiotics may exert their antiviral activity by (1) direct probiotic-virus interaction; (2) production of antiviral inhibitory metabolites; and/or (3) via stimulation of the immune system. The aim of this review was to highlight the antiviral activity of LAB and substances they produce with antiviral activity.

  15. Determination of peroxy radical-scavenging of lactic acid bacteria.

    PubMed

    Stecchini, M L; Del Torre, M; Munari, M

    2001-02-28

    Responses of lactic acid bacteria (LAB) to peroxy radicals generated via thermal (40 degrees C) decomposition of the diazocompound 2,2,-azo-bis (2-amidinopropane) dihydrochloride (ABAP), were studied. In general, LAB displayed survival curves with shoulders and tails indicative of 'multihit' killing by exposure to peroxy radicals. One strain, Lactococcus lactis subsp. lactis DIP15, producing a slope of 0.0105 in the kinetic analysis when exposed to 4 mM ABAP, exhibited a measurable antioxidant capacity. The other LAB failed to show any significant antioxidant capacity. The antioxidant capacity of strain DIP15 remained constant after cells have been heat-treated, suggesting that compounds bearing free radical scavenging capacity are rather stable.

  16. Poly(lactic acid) for delivery of bioactive macromolecules.

    PubMed

    James, Roshan; Manoukian, Ohan S; Kumbar, Sangamesh G

    2016-12-15

    Therapeutic biomolecules often require frequent administration and supramolecular dosing to achieve therapeutic efficiencies and direct infusion into treatment or defect sites results in inadequate physiological response and at times severe side effects or mis-targeting. Delivery systems serve several purposes such as increased circulatory time, increased biomolecule half-life, and incorporation of new innovations can enable highly specific cell targeting and improved cell and nucleus permeability. Poly(lactic acid) (PLA) has become a "material of choice" due to wide availability, reproducible synthetic route, customization, versatility, biodegradability and biocompatibility. Furthermore, PLA is amenable to a variety of fabrication methodologies and chemistries allowing an expansive library correlating physio-chemical properties, characteristics, and applications. This article discusses challenges to biomolecule delivery, and classical approaches of PLA based biomolecule delivery and targeting strategies under development and in trials.

  17. Frustrated smectic liquid crystalline phases in lactic acid derivatives

    NASA Astrophysics Data System (ADS)

    Glogarová, M.; Novotná, V.

    2016-08-01

    We have prepared and studied a series of compounds with different types of molecular core and lactate unit in the chiral terminal chain. We draw a survey and comparison of their mesomorphic properties with respect to the occurrence of twist grain boundary (TGB) phases. The materials exhibit extremely wide TGBA phase more than 60K broad, unique TGBA-TGBC-SmC*-SmCA* phase sequence and unique re-entrant TGBA phase below the SmA phase. TGB phases have been induced in binary mixtures of molecules with different molecular shape and chirality (chiral lactic acid derivative and non-chiral hockey-stick mesogen). Unique effect is observed for compounds with TGBA phase, where the applied electric field transforms the planar texture into the homeotropic one, homogeneously dark in crossed polarizers. The process is analogy of the Frederiks transition so far known only for nematics. This effect, changing the bright state to the dark one, is promising for applications.

  18. Regulation of acetic acid production by homo- and heterofermentative lactobacilli in whole-wheat sour-doughs.

    PubMed

    Martínez-Anaya, M A; Llin, M L; Pilar Macías, M; Collar, C

    1994-09-01

    The efficiency of sour-dough as a possible preservative agent of microbial spoilage of bread depends on its acetic acid content. As a secondary metabolite of sugar fermentation by lactic acid bacteria, acetic acid may be promoted in the presence of O2 or H+ acceptors. This paper studies the influence of O2 and high fructose content products (pure sugar, invert sugar, fructose syrup) addition on acetic acid production by hetero- (Lactobacillus brevis 25a, B-21, L-62; L. sanfrancisco L-99) and homofermentative (L. plantarum B-39) lactobacilli in whole-wheat sour-doughs [280 and 250 dough yield (DY)]. The pH and total titratable acidity (TTA) of sour-doughs after 44 h fermentation varied with DY and strain. As expected, the addition of O2 promoted greater increases in TTA with heterofermentative lactobacilli (15-42%) than with L. plantarum (15%). Fructose addition was only effective for heterofermentative strains, but the overall effects were smaller than those observed for oxygenation. The ability of lactobacilli to produce acetic acid in sour-doughs without treatment varied from 0.16 g/100 g flour at 44 h (B-39, 280, 350 DY) to 0.47-0.65% (L-62, 280, 350 DY). The production of acetic acid was positively promoted by all treatments. Oxygenation was again the most effective way of inducing acetic acid production; increases ranged from 54% (B-21) to 269% (L-99, 350 DY). The addition of H+ acceptors had variable effects.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. A glutamic acid-producing lactic acid bacteria isolated from Malaysian fermented foods.

    PubMed

    Zareian, Mohsen; Ebrahimpour, Afshin; Bakar, Fatimah Abu; Mohamed, Abdul Karim Sabo; Forghani, Bita; Ab-Kadir, Mohd Safuan B; Saari, Nazamid

    2012-01-01

    l-glutamaic acid is the principal excitatory neurotransmitter in the brain and an important intermediate in metabolism. In the present study, lactic acid bacteria (218) were isolated from six different fermented foods as potent sources of glutamic acid producers. The presumptive bacteria were tested for their ability to synthesize glutamic acid. Out of the 35 strains showing this capability, strain MNZ was determined as the highest glutamic-acid producer. Identification tests including 16S rRNA gene sequencing and sugar assimilation ability identified the strain MNZ as Lactobacillus plantarum. The characteristics of this microorganism related to its glutamic acid-producing ability, growth rate, glucose consumption and pH profile were studied. Results revealed that glutamic acid was formed inside the cell and excreted into the extracellular medium. Glutamic acid production was found to be growth-associated and glucose significantly enhanced glutamic acid production (1.032 mmol/L) compared to other carbon sources. A concentration of 0.7% ammonium nitrate as a nitrogen source effectively enhanced glutamic acid production. To the best of our knowledge this is the first report of glutamic acid production by lactic acid bacteria. The results of this study can be further applied for developing functional foods enriched in glutamic acid and subsequently γ-amino butyric acid (GABA) as a bioactive compound.

  20. Condensation of acetol and acetic acid vapor with sprayed liquid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A cellulose-derived fraction of biomass pyrolysis vapor was simulated by evaporating acetol and acetic acid (AA) from flasks on a hot plate. The liquid in the flasks was infused with heated nitrogen. The vapor/nitrogen stream was superheated in a tube oven and condensed by contact with a cloud of ...

  1. Intramolecular carbon isotope distribution of acetic acid in vinegar.

    PubMed

    Hattori, Ryota; Yamada, Keita; Kikuchi, Makiko; Hirano, Satoshi; Yoshida, Naohiro

    2011-09-14

    Compound-specific carbon isotope analysis of acetic acid is useful for origin discrimination and quality control of vinegar. Intramolecular carbon isotope distributions, which are each carbon isotope ratios of the methyl and carboxyl carbons in the acetic acid molecule, may be required to obtain more detailed information to discriminate such origin. In this study, improved gas chromatography-pyrolysis-gas chromatography-combustion-isotope ratio mass spectrometry (GC-Py-GC-C-IRMS) combined with headspace solid-phase microextraction (HS-SPME) was used to measure the intramolecular carbon isotope distributions of acetic acid in 14 Japanese vinegars. The results demonstrated that the methyl carbons of acetic acid molecules in vinegars produced from plants were mostly isotopically depleted in (13)C relative to the carboxyl carbon. Moreover, isotopic differences (δ(13)C(carboxyl) - δ(13)C(methyl)) had a wide range from -0.3 to 18.2‰, and these values differed among botanical origins, C3, C4, and CAM plants.

  2. Who will win the race in childrens' oral cavities? Streptococcus mutans or beneficial lactic acid bacteria?

    PubMed

    Güngör, Ö E; Kırzıoğlu, Z; Dinçer, E; Kıvanç, M

    2013-09-01

    Adhesion to oral soft and hard tissue is crucial for bacterial colonisation in the mouth. The aim of this work was to select strains of oral lactic acid bacteria that could be used as probiotics for oral health. To this end, the adhesive properties of some lactic acid bacteria were investigated. Seventeen lactic acid bacteria including two Streptococcus mutans strains were isolated from the oral cavity of healthy children, while other strains were isolated from fermented meat products. The bacterial strains were applied to teeth surfaces covered with saliva or without saliva. A significant diversity in adhesion capacity to teeth surfaces among the lactic acid bacteria was observed. Lactic acid bacteria isolated from the oral cavity adhered the best to teeth surfaces covered with saliva, whereas lactic acid bacteria isolated from fermented meat samples adhered the best to tooth surface without saliva. All strains of lactic acid bacteria were able to reduce the number of S. mutans cells, in particular on saliva-coated tooth surface. Therefore, they might have potential as probiotics for the oral cavity.

  3. Separate and Concentrate Lactic Acid Using Combination of Nanofiltration and Reverse Osmosis Membranes

    NASA Astrophysics Data System (ADS)

    Li, Yebo; Shahbazi, Abolghasem; Williams, Karen; Wan, Caixia

    The processes of lactic acid production include two key stages, which are (a) fermentation and (b) product recovery. In this study, free cell of Bifidobacterium longum was used to produce lactic acid from cheese whey. The produced lactic acid was then separated and purified from the fermentation broth using combination of nanofiltration and reverse osmosis membranes. Nanofiltration membrane with a molecular weight cutoff of 100-400 Da was used to separate lactic acid from lactose and cells in the cheese whey fermentation broth in the first step. The obtained permeate from the above nanofiltration is mainly composed of lactic acid and water, which was then concentrated with a reverse osmosis membrane in the second step. Among the tested nanofiltration membranes, HL membrane from GE Osmonics has the highest lactose retention (97±1%). In the reverse osmosis process, the ADF membrane could retain 100% of lactic acid to obtain permeate with water only. The effect of membrane and pressure on permeate flux and retention of lactose/lactic acid was also reported in this paper.

  4. Effects of lactic acid and NaCl on creatine kinase from rabbit muscle.

    PubMed

    Tang, Hong-Min; Ou, Wen-Bin; Zhou, Hai-Meng

    2003-02-01

    The lactic acid induced unfolding and the salt-induced folding of creatine kinase (CK) were studied by enzyme activity, fluorescence emission spectra, circular dichroism spectra, and native polyacrylamide gel electrophoresis. The results showed that the kinetics of CK inactivation was a monophase process. Lactic acid caused inactivation and unfolding of CK with no aggregation during CK denaturation. The unfolding of the whole molecule and the inactivation of CK in solutions of different concentration of lactic acid were compared. Much lower lactic acid concentration values were required to bring about inactivation than were required to produce significant conformational changes of the enzyme molecule. At higher concentrations of lactic acid (more than 0.2 mM) the CK dimers were partially dissociated, as proved by native polyacrylamide gel electrophoresis. NaCl induced the molten globule state with a compact structure after CK was denatured with 0.8 mM lactic acid, and the increasing of anions led to a tight side-chain. The above results suggest that the effect of lactic acid differed from that of other denaturants such as guanidine hydrochloride, HCI, or urea during CK folding, and the molten globule state indicates that intermediates exist during CK folding.

  5. Separate and concentrate lactic acid using combination of nanofiltration and reverse osmosis membranes.

    PubMed

    Li, Yebo; Shahbazi, Abolghasem; Williams, Karen; Wan, Caixia

    2008-03-01

    The processes of lactic acid production include two key stages, which are (a) fermentation and (b) product recovery. In this study, free cell of Bifidobacterium longum was used to produce lactic acid from cheese whey. The produced lactic acid was then separated and purified from the fermentation broth using combination of nanofiltration and reverse osmosis membranes. Nanofiltration membrane with a molecular weight cutoff of 100-400 Da was used to separate lactic acid from lactose and cells in the cheese whey fermentation broth in the first step. The obtained permeate from the above nanofiltration is mainly composed of lactic acid and water, which was then concentrated with a reverse osmosis membrane in the second step. Among the tested nanofiltration membranes, HL membrane from GE Osmonics has the highest lactose retention (97 +/- 1%). In the reverse osmosis process, the ADF membrane could retain 100% of lactic acid to obtain permeate with water only. The effect of membrane and pressure on permeate flux and retention of lactose/lactic acid was also reported in this paper.

  6. Poly(lactic-co-glycolic acid) conduit for repair of injured sciatic nerve: A mechanical analysis

    PubMed Central

    Yu, Tao; Zhao, Changfu; Li, Peng; Liu, Guangyao; Luo, Min

    2013-01-01

    Tensile stress and tensile strain directly affect the quality of nerve regeneration after bridging nerve defects by poly(lactic-co-glycolic acid) conduit transplantation and autogenous nerve grafting for sciatic nerve injury. This study collected the sciatic nerve from the gluteus maximus muscle from fresh human cadaver, and established 10-mm-long sciatic nerve injury models by removing the ischium, following which poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts were transplanted. Scanning electron microscopy revealed that the axon and myelin sheath were torn, and the vessels of basilar membrane were obstructed in the poly(lactic-co-glycolic acid) conduit-repaired sciatic nerve following tensile testing. There were no significant differences in tensile tests with autogenous nerve graft-repaired sciatic nerve. Following poly(lactic-co-glycolic acid) conduit transplantation for sciatic nerve repair, tensile test results suggest that maximum tensile load, maximum stress, elastic limit load and elastic limit stress increased compared with autogenous nerve grafts, but elastic limit strain and maximum strain decreased. Moreover, the tendencies of stress-strain curves of sciatic nerves were similar after transplantation of poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts. Results showed that after transplantation in vitro for sciatic nerve injury, poly(lactic-co-glycolic acid) conduits exhibited good intensity, elasticity and plasticity, indicating that poly(lactic-co-glycolic acid) conduits are suitable for sciatic nerve injury repair. PMID:25206505

  7. Wireless Biosensor System for Real-Time l-Lactic Acid Monitoring in Fish

    PubMed Central

    Hibi, Kyoko; Hatanaka, Kengo; Takase, Mai; Ren, Huifeng; Endo, Hideaki

    2012-01-01

    We have developed a wireless biosensor system to continuously monitor l-lactic acid concentrations in fish. The blood l-lactic acid level of fish is a barometer of stress. The biosensor comprised Pt-Ir wire (φ0.178 mm) as the working electrode and Ag/AgCl paste as the reference electrode. Lactate oxidase was immobilized on the working electrode using glutaraldehyde. The sensor calibration was linear and good correlated with l-lactic acid levels (R = 0.9959) in the range of 0.04 to 6.0 mg·dL−1. We used the eyeball interstitial sclera fluid (EISF) as the site of sensor implantation. The blood l-lactic acid levels correlated closely with the EISF l-lactic acid levels in the range of 3 to 13 mg·dL−1 (R = 0.8173, n = 26). Wireless monitoring of l-lactic acid was performed using the sensor system in free-swimming fish in an aquarium. The sensor response was stable for over 60 h. Thus, our biosensor provided a rapid and convenient method for real-time monitoring of l-lactic acid levels in fish. PMID:22778641

  8. Antimicrobial Effect of Calcium Chloride Alone and Combined with Lactic Acid Injected into Chicken Breast Meat

    PubMed Central

    Alahakoon, Amali U.; Jayasena, Dinesh D.; Jung, Samooel; Kim, Sun Hyo

    2014-01-01

    Chicken breast meat was injected with calcium chloride alone and in combination with lactic acid (0.01% and 0.002%, respectively). The inhibitory effects of the treatments on microbial growth were determined in the injected chicken breast meat stored at 4°C under aerobic packaging condition for 0, 3, and 7 d. Calcium chloride combined with 0.002% and 0.01% lactic acid reduced microbial counts by 0.14 and 1.08 Log CFU/g, respectively, however, calcium chloride alone was unable to inhibit microbial growth. Calcium chloride combined with 0.01% lactic acid was the most effective antimicrobial treatment and resulted in the highest initial redness value. Calcium chloride alone and combined with lactic acid suppressed changes in pH and the Hunter color values during storage. However, injection of calcium chloride and lactic acid had adverse effects on lipid oxidation and sensory characteristics. The higher TBARS values were observed in samples treated with calcium chloride and lactic acid when compared to control over the storage period. Addition of calcium chloride and lactic acid resulted in lower sensory scores for parameters tested, except odor and color, compared to control samples. Therefore, the formulation should be improved in order to overcome such defects prior to industrial application. PMID:26760942

  9. Poly(lactic-co-glycolic acid) conduit for repair of injured sciatic nerve: A mechanical analysis.

    PubMed

    Yu, Tao; Zhao, Changfu; Li, Peng; Liu, Guangyao; Luo, Min

    2013-07-25

    Tensile stress and tensile strain directly affect the quality of nerve regeneration after bridging nerve defects by poly(lactic-co-glycolic acid) conduit transplantation and autogenous nerve grafting for sciatic nerve injury. This study collected the sciatic nerve from the gluteus maximus muscle from fresh human cadaver, and established 10-mm-long sciatic nerve injury models by removing the ischium, following which poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts were transplanted. Scanning electron microscopy revealed that the axon and myelin sheath were torn, and the vessels of basilar membrane were obstructed in the poly(lactic-co-glycolic acid) conduit-repaired sciatic nerve following tensile testing. There were no significant differences in tensile tests with autogenous nerve graft-repaired sciatic nerve. Following poly(lactic-co-glycolic acid) conduit transplantation for sciatic nerve repair, tensile test results suggest that maximum tensile load, maximum stress, elastic limit load and elastic limit stress increased compared with autogenous nerve grafts, but elastic limit strain and maximum strain decreased. Moreover, the tendencies of stress-strain curves of sciatic nerves were similar after transplantation of poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts. Results showed that after transplantation in vitro for sciatic nerve injury, poly(lactic-co-glycolic acid) conduits exhibited good intensity, elasticity and plasticity, indicating that poly(lactic-co-glycolic acid) conduits are suitable for sciatic nerve injury repair.

  10. Highly efficient production of D-lactic acid from chicory-derived inulin by Lactobacillus bulgaricus.

    PubMed

    Xu, Qianqian; Zang, Ying; Zhou, Jie; Liu, Peng; Li, Xin; Yong, Qiang; Ouyang, Jia

    2016-11-01

    Inulin is a readily available feedstock for cost-effective production of biochemicals. To date, several studies have explored the production of bioethanol, high-fructose syrup and fructooligosaccharide, but there are no studies regarding the production of D-lactic acid using inulin as a carbon source. In the present study, chicory-derived inulin was used for D-lactic acid biosynthesis by Lactobacillus bulgaricus CGMCC 1.6970. Compared with separate hydrolysis and fermentation processes, simultaneous saccharification and fermentation (SSF) has demonstrated the best performance of D-lactic acid production. Because it prevents fructose inhibition and promotes the complete hydrolysis of inulin, the highest D-lactic acid concentration (123.6 ± 0.9 g/L) with a yield of 97.9 % was obtained from 120 g/L inulin by SSF. Moreover, SSF by L. bulgaricus CGMCC 1.6970 offered another distinct advantage with respect to the higher optical purity of D-lactic acid (>99.9 %) and reduced number of residual sugars. The excellent performance of D-lactic acid production from inulin by SSF represents a high-yield method for D-lactic acid production from non-food grains.

  11. Diversity of the Lactic Acid Bacterium and Yeast Microbiota in the Switch from Firm- to Liquid-Sourdough Fermentation

    PubMed Central

    Di Cagno, Raffaella; Pontonio, Erica; Buchin, Solange; De Angelis, Maria; Lattanzi, Anna; Valerio, Francesca; Calasso, Maria

    2014-01-01

    Four traditional type I sourdoughs were comparatively propagated (28 days) under firm (dough yield, 160) and liquid (dough yield, 280) conditions to mimic the alternative technology options frequently used for making baked goods. After 28 days of propagation, liquid sourdoughs had the lowest pH and total titratable acidity (TTA), the lowest concentrations of lactic and acetic acids and free amino acids, and the most stable density of presumptive lactic acid bacteria. The cell density of yeasts was the highest in liquid sourdoughs. Liquid sourdoughs showed simplified microbial diversity and harbored a low number of strains, which were persistent. Lactobacillus plantarum dominated firm sourdoughs over time. Leuconostoc lactis and Lactobacillus brevis dominated only some firm sourdoughs, and Lactobacillus sanfranciscensis persisted for some time only in some firm sourdoughs. Leuconostoc citreum persisted in all firm and liquid sourdoughs, and it was the only species detected in liquid sourdoughs at all times; it was flanked by Leuconostoc mesenteroides in some sourdoughs. Saccharomyces cerevisiae, Candida humilis, Saccharomyces servazzii, Saccharomyces bayanus-Kazachstania sp., and Torulaspora delbrueckii were variously identified in firm and liquid sourdoughs. A total of 197 volatile components were identified through purge and trap–/solid-phase microextraction–gas chromatography-mass spectrometry (PT–/SPME–GC-MS). Aldehydes, several alcohols, and some esters were at the highest levels in liquid sourdoughs. Firm sourdoughs mainly contained ethyl acetate, acetic acid, some sulfur compounds, and terpenes. The use of liquid fermentation would change the main microbial and biochemical features of traditional baked goods, which have been manufactured under firm conditions for a long time. PMID:24632249

  12. Nonstarter lactic acid bacteria volatilomes produced using cheese components.

    PubMed

    Sgarbi, E; Lazzi, C; Tabanelli, G; Gatti, M; Neviani, E; Gardini, F

    2013-07-01

    In long-ripened cheese, flavor formation occurs during ripening. The metabolism of lactic acid bacteria (LAB) leads to the production of different compounds that contribute to the flavor of cheese. The contribution of LAB to the formation of cheese flavor has previously been studied. However, the specific nonstarter LAB (NSLAB) metabolic reactions in ripened cheese that lead to the formation of flavor compounds remain unclear. In ripened cheese, the nutrient sources available include small peptides or amino acids, citrate, lactate, free fatty acids, and starter LAB cell lysis products. Thus, the aim of this study was to evaluate the ability of NSLAB to produce volatile flavor compounds by using an in vitro system that used only the nutrients available in ripened cheese as the energy source. Moreover, the potential contribution of the NSLAB volatilome on total cheese flavor is discussed. For this purpose, the production of volatile compounds on cheese-based medium (CBM) and on starter LAB lysed cell medium (LCM) by 2 Lactobacillus casei and 2 Lactobacillus rhamnosus strains, previously isolated from ripened Parmigiano Reggiano cheese, was investigated. The generated volatile compounds were analyzed with head-space gas chromatography mass spectrometry. Overall, ketones, aldehydes, alcohols, and acids were the most abundant compounds produced. Differences in volatilome production were found between NSLAB grown in LCM and CBM. The catabolic metabolism of amino acids and fatty acids were required for NSLAB growth on LCM. Conversely, pyruvate metabolism was the main catabolic pathway that supported growth of NSLAB in CBM. This study can be considered a first step toward a better understanding of how microbiota involved in the long ripening of cheese may contribute to the development of cheese flavor.

  13. Lactic acid permeabilizes gram-negative bacteria by disrupting the outer membrane.

    PubMed

    Alakomi, H L; Skyttä, E; Saarela, M; Mattila-Sandholm, T; Latva-Kala, K; Helander, I M

    2000-05-01

    The effect of lactic acid on the outer membrane permeability of Escherichia coli O157:H7, Pseudomonas aeruginosa, and Salmonella enterica serovar Typhimurium was studied utilizing a fluorescent-probe uptake assay and sensitization to bacteriolysis. For control purposes, similar assays were performed with EDTA (a permeabilizer acting by chelation) and with hydrochloric acid, the latter at pH values corresponding to those yielded by lactic acid, and also in the presence of KCN. Already 5 mM (pH 4.0) lactic acid caused prominent permeabilization in each species, the effect in the fluorescence assay being stronger than that of EDTA or HCl. Similar results were obtained in the presence of KCN, except for P. aeruginosa, for which an increase in the effect of HCl was observed in the presence of KCN. The permeabilization by lactic and hydrochloric acid was partly abolished by MgCl(2). Lactic acid sensitized E. coli and serovar Typhimurium to the lytic action of sodium dodecyl sulfate (SDS) more efficiently than did HCl, whereas both acids sensitized P. aeruginosa to SDS and to Triton X-100. P. aeruginosa was effectively sensitized to lysozyme by lactic acid and by HCl. Considerable proportions of lipopolysaccharide were liberated from serovar Typhimurium by these acids; analysis of liberated material by electrophoresis and by fatty acid analysis showed that lactic acid was more active than EDTA or HCl in liberating lipopolysaccharide from the outer membrane. Thus, lactic acid, in addition to its antimicrobial property due to the lowering of the pH, also functions as a permeabilizer of the gram-negative bacterial outer membrane and may act as a potentiator of the effects of other antimicrobial substances.

  14. Lactic Acid Permeabilizes Gram-Negative Bacteria by Disrupting the Outer Membrane

    PubMed Central

    Alakomi, H.-L.; Skyttä, E.; Saarela, M.; Mattila-Sandholm, T.; Latva-Kala, K.; Helander, I. M.

    2000-01-01

    The effect of lactic acid on the outer membrane permeability of Escherichia coli O157:H7, Pseudomonas aeruginosa, and Salmonella enterica serovar Typhimurium was studied utilizing a fluorescent-probe uptake assay and sensitization to bacteriolysis. For control purposes, similar assays were performed with EDTA (a permeabilizer acting by chelation) and with hydrochloric acid, the latter at pH values corresponding to those yielded by lactic acid, and also in the presence of KCN. Already 5 mM (pH 4.0) lactic acid caused prominent permeabilization in each species, the effect in the fluorescence assay being stronger than that of EDTA or HCl. Similar results were obtained in the presence of KCN, except for P. aeruginosa, for which an increase in the effect of HCl was observed in the presence of KCN. The permeabilization by lactic and hydrochloric acid was partly abolished by MgCl2. Lactic acid sensitized E. coli and serovar Typhimurium to the lytic action of sodium dodecyl sulfate (SDS) more efficiently than did HCl, whereas both acids sensitized P. aeruginosa to SDS and to Triton X-100. P. aeruginosa was effectively sensitized to lysozyme by lactic acid and by HCl. Considerable proportions of lipopolysaccharide were liberated from serovar Typhimurium by these acids; analysis of liberated material by electrophoresis and by fatty acid analysis showed that lactic acid was more active than EDTA or HCl in liberating lipopolysaccharide from the outer membrane. Thus, lactic acid, in addition to its antimicrobial property due to the lowering of the pH, also functions as a permeabilizer of the gram-negative bacterial outer membrane and may act as a potentiator of the effects of other antimicrobial substances. PMID:10788373

  15. Mechanism of Synergistic Inhibition of Listeria monocytogenes Growth by Lactic Acid, Monolaurin, and Nisin▿

    PubMed Central

    Tokarskyy, Oleksandr; Marshall, Douglas L.

    2008-01-01

    The combined lactic acid, monolaurin, and nisin effects on time-to-detection (optical density at 600 nm) extension were greater (P < 0.05) than any single or paired combination effect, which demonstrates a synergistic interaction among the antimicrobials. Monolaurin exposure caused C12:0 cell membrane incorporation. Lactic acid caused increased monolaurin C12:0 membrane incorporation, while nisin had no influence. We postulate that lactic acid-enhanced monolaurin C12:0 incorporation into the cell membrane increased membrane fluidity resulting in increased nisin activity. PMID:18820062

  16. Mechanism of synergistic inhibition of Listeria monocytogenes growth by lactic acid, monolaurin, and nisin.

    PubMed

    Tokarskyy, Oleksandr; Marshall, Douglas L

    2008-12-01

    The combined lactic acid, monolaurin, and nisin effects on time-to-detection (optical density at 600 nm) extension were greater (P < 0.05) than any single or paired combination effect, which demonstrates a synergistic interaction among the antimicrobials. Monolaurin exposure caused C12:0 cell membrane incorporation. Lactic acid caused increased monolaurin C12:0 membrane incorporation, while nisin had no influence. We postulate that lactic acid-enhanced monolaurin C12:0 incorporation into the cell membrane increased membrane fluidity resulting in increased nisin activity.

  17. Use of wastewater sludge as a raw material for production of L-lactic acid

    SciTech Connect

    Nakasaki, Kiyohiko; Akakura, Naoki; Adachi, Tomohiko; Akiyama, Tetsuo

    1999-01-01

    This study utilizes wastewater sludges to produce L-lactic acid, a precursor of biodegradable plastic. The high concentrations of cellulose contained in the sludge, derived from a paper manufacturing facility, have been found to be convertible to L-lactic acid at a rate as high as 6.91 g/L. To achieve such a high conversion rate, the sludge must be pretreated with cellulase. This pretreatment includes inoculation of the sludge with lactic acid bacteria, strain LA1, after the sludge has been subjected to enzymatic hydrolysis.

  18. Occurrence and metabolism of 7-hydroxy-2-indolinone-3-acetic acid in Zea mays

    NASA Technical Reports Server (NTRS)

    Lewer, P.; Bandurski, R. S.

    1987-01-01

    7-Hydroxy-2-indolinone-3-acetic acid was identified as a catabolite of indole-3-acetic acid in germinating kernels of Zea mays and found to be present in amounts of ca 3.1 nmol/kernel. 7-Hydroxy-2-indolinone-3-acetic acid was shown to be a biosynthetic intermediate between 2-indolinone-3-acetic acid and 7-hydroxy-2-indolinone-3-acetic acid-7'-O-glucoside in both kernels and roots of Zea mays. Further metabolism of 7-hydroxy-2-[5-3H]-indolinone-3-acetic acid-7'-O-glucoside occurred to yield tritiated water plus, as yet, uncharacterized products.

  19. Simultaneous production of acetic and gluconic acids by a thermotolerant Acetobacter strain during acetous fermentation in a bioreactor.

    PubMed

    Mounir, Majid; Shafiei, Rasoul; Zarmehrkhorshid, Raziyeh; Hamouda, Allal; Ismaili Alaoui, Mustapha; Thonart, Philippe

    2016-02-01

    The activity of bacterial strains significantly influences the quality and the taste of vinegar. Previous studies of acetic acid bacteria have primarily focused on the ability of bacterial strains to produce high amounts of acetic acid. However, few studies have examined the production of gluconic acid during acetous fermentation at high temperatures. The production of vinegar at high temperatures by two strains of acetic acid bacteria isolated from apple and cactus fruits, namely AF01 and CV01, respectively, was evaluated in this study. The simultaneous production of gluconic and acetic acids was also examined in this study. Biochemical and molecular identification based on a 16s rDNA sequence analysis confirmed that these strains can be classified as Acetobacter pasteurianus. To assess the ability of the isolated strains to grow and produce acetic acid and gluconic acid at high temperatures, a semi-continuous fermentation was performed in a 20-L bioreactor. The two strains abundantly grew at a high temperature (41°C). At the end of the fermentation, the AF01 and CV01 strains yielded acetic acid concentrations of 7.64% (w/v) and 10.08% (w/v), respectively. Interestingly, CV01 was able to simultaneously produce acetic and gluconic acids during acetic fermentation, whereas AF01 mainly produced acetic acid. In addition, CV01 was less sensitive to ethanol depletion during semi-continuous fermentation. Finally, the enzymatic study showed that the two strains exhibited high ADH and ALDH enzyme activity at 38°C compared with the mesophilic reference strain LMG 1632, which was significantly susceptible to thermal inactivation.

  20. Phenolic acid degradation potential and growth behavior of lactic acid bacteria in sunflower substrates.

    PubMed

    Fritsch, Caroline; Heinrich, Veronika; Vogel, Rudi F; Toelstede, Simone

    2016-08-01

    Sunflower flour provides a high content of protein with a well-balanced amino acid composition and is therefore regarded as an attractive source for protein. The use for human nutrition is hindered by phenolic compounds, mainly chlorogenic acid, which can lead under specific circumstances to undesirable discolorations. In this study, growth behavior and degradation ability of chlorogenic acid of four lactic acid bacteria were explored. Data suggested that significant higher fermentation performances on sunflower flour as compared to sunflower protein concentrate were reached by Lactobacillus plantarum, Pediococcus pentosaceus, Lactobacillus gasseri and Bifidobacterium animalis subsp. lactis. In fermentation with the latter two strains reduced amounts of chlorogenic acid were observed in sunflower flour (-11.4% and -19.8%, respectively), which were more pronounced in the protein concentrate (-50.7% and -95.6%, respectively). High tolerances against chlorogenic acid and the cleavage product quinic acid with a minimum inhibitory concentration (MIC) of ≥20.48 mg/ml after 48 h were recorded for all strains except Bifidobacterium animalis subsp. lactis, which was more sensitive. The second cleavage compound, caffeic acid revealed a higher antimicrobial potential with MIC values of 0.64-5.12 mg/ml. In this proof of concept study, degradation versus inhibitory effect suggest the existence of basic mechanisms of interaction between phenolic acids in sunflower and lactic acid bacteria and a feasible way to reduce the chlorogenic acid content, which may help to avoid undesired color changes.

  1. Acid hydrolysis of Curcuma longa residue for ethanol and lactic acid fermentation.

    PubMed

    Nguyen, Cuong Mai; Nguyen, Thanh Ngoc; Choi, Gyung Ja; Choi, Yong Ho; Jang, Kyoung Soo; Park, Youn-Je; Kim, Jin-Cheol

    2014-01-01

    This research examines the acid hydrolysis of Curcuma longa waste, to obtain the hydrolysate containing lactic acid and ethanol fermentative sugars. A central composite design for describing regression equations of variables was used. The selected optimum condition was 4.91% sulphuric acid, 122.68°C and 50 min using the desirability function under the following conditions: the maximum reducing sugar (RS) yield is within the limited range of the 5-hydroxymethylfurfural (HMF) and furfural concentrations. Under the condition, the obtained solution contained 144 g RS/L, 0.79 g furfural/L and 2.59 g HMF/L and was directly fermented without a detoxification step. The maximum product concentration, average productivity, RS conversion and product yield were 115.36 g/L, 2.88 g/L/h, 89.43% and 64% for L-lactic acid; 113.92 g/L, 2.59 g/L/h, 88.31% and 63.29% for D-lactic acid; and 55.03 g/L, 1.38 g/L/h, 42.66 and 30.57%, respectively, for ethanol using a 7-L jar fermenter.

  2. [Conversion of acetic acid to methane by thermophiles: Progress report

    SciTech Connect

    Zinder, S.

    1991-12-31

    The objective of this project is to provide an understanding of thermophilic anaerobic microorganisms capable of breaking down acetic acid, the precursor of two-thirds of the methane produced by anaerobic bioreactors. Recent results include: (1) the isolation of Methanothrix strain CALLS-1, which grows much more rapidly than mesophilic strains; (2) the demonstration that thermophilic cultures of Methanosarcina and Methanothrix show minimum thresholds for acetate utilization of 1--2.5 mM and 10--20{mu}m respectively, in agreement with ecological data indicating that Methanothrix is favored by low acetate concentration; (3) the demonstration of high levels of thermostable acetyl-coA synthetase and carbon monoxide dehydrogenase in cell-free extracts of Methanothrix strains CALS-1; (4) the demonstration of methanogenesis from acetate and ATP in cell free extracts of strain CALS-1. (5) the demonstration that methanogenesis from acetate required 2 ATP/methane, and, in contrast to Methanosarcina, was independent of hydrogen and other electron donors; (6) the finding that entropy effects must be considered when predicting the level of hydrogen in thermophilic syntrophic cultures. (7) the isolation and characterization of the Desulfotomaculum thermoacetoxidans. Current research is centered on factors which allow thermophilic Methanothrix to compete with Methanosarcina.

  3. (Conversion of acetic acid to methane by thermophiles: Progress report)

    SciTech Connect

    Zinder, S.

    1991-01-01

    The objective of this project is to provide an understanding of thermophilic anaerobic microorganisms capable of breaking down acetic acid, the precursor of two-thirds of the methane produced by anaerobic bioreactors. Recent results include: (1) the isolation of Methanothrix strain CALLS-1, which grows much more rapidly than mesophilic strains; (2) the demonstration that thermophilic cultures of Methanosarcina and Methanothrix show minimum thresholds for acetate utilization of 1--2.5 mM and 10--20{mu}m respectively, in agreement with ecological data indicating that Methanothrix is favored by low acetate concentration; (3) the demonstration of high levels of thermostable acetyl-coA synthetase and carbon monoxide dehydrogenase in cell-free extracts of Methanothrix strains CALS-1; (4) the demonstration of methanogenesis from acetate and ATP in cell free extracts of strain CALS-1. (5) the demonstration that methanogenesis from acetate required 2 ATP/methane, and, in contrast to Methanosarcina, was independent of hydrogen and other electron donors; (6) the finding that entropy effects must be considered when predicting the level of hydrogen in thermophilic syntrophic cultures. (7) the isolation and characterization of the Desulfotomaculum thermoacetoxidans. Current research is centered on factors which allow thermophilic Methanothrix to compete with Methanosarcina.

  4. Assessing physio-macromolecular effects of lactic acid on Zygosaccharomyces bailii cells during microaerobic fermentation.

    PubMed

    Kuanyshev, Nurzhan; Ami, Diletta; Signori, Lorenzo; Porro, Danilo; Morrissey, John P; Branduardi, Paola

    2016-08-01

    The ability of Zygosaccharomyces bailii to grow at low pH and in the presence of considerable amounts of weak organic acids, at lethal condition for Saccharomyces cerevisiae, increased the interest in the biotechnological potential of the yeast. To understand the mechanism of tolerance and growth effect of weak acids on Z. bailii, we evaluated the physiological and macromolecular changes of the yeast exposed to sub lethal concentrations of lactic acid. Lactic acid represents one of the important commodity chemical which can be produced by microbial fermentation. We assessed physiological effect of lactic acid by bioreactor fermentation using synthetic media at low pH in the presence of lactic acid. Samples collected from bioreactors were stained with propidium iodide (PI) which revealed that, despite lactic acid negatively influence the growth rate, the number of PI positive cells is similar to that of the control. Moreover, we have performed Fourier Transform Infra-Red (FTIR) microspectroscopy analysis on intact cells of the same samples. This technique has been never applied before to study Z. bailii under this condition. The analyses revealed lactic acid induced macromolecular changes in the overall cellular protein secondary structures, and alterations of cell wall and membrane physico-chemical properties.

  5. Lactic acid bacterial extract as a biogenic mineral growth modifier

    NASA Astrophysics Data System (ADS)

    Borah, Ballav M.; Singh, Atul K.; Ramesh, Aiyagari; Das, Gopal

    2009-04-01

    The formation of minerals and mechanisms by which bacteria could control their formation in natural habitats is now of current interest for material scientists to have an insight of the mechanism of in vivo mineralization, as well as to seek industrial and technological applications. Crystalline uniform structures of calcium and barium minerals formed micron-sized building blocks when synthesized in the presence of an organic matrix consisting of secreted protein extracts from three different lactic acid bacteria (LAB) viz.: Lactobacillus plantarum MTCC 1325, Lactobacillus acidophilus NRRL B4495 and Pediococcus acidilactici CFR K7. LABs are not known to form organic matrix in biological materialization processes. The influence of these bacterial extracts on the crystallization behavior was investigated in details to test the basic coordination behavior of the acidic protein. In this report, varied architecture of the mineral crystals obtained in presence of high molecular weight protein extracts of three different LAB strains has been discussed. The role of native form of high molecular weight bacterial protein extracts in the generation of nucleation centers for crystal growth was clearly established. A model for the formation of organic matrix-cation complex and the subsequent events leading to crystal growth is proposed.

  6. Evaporation kinetics of acetic acid-water solutions

    NASA Astrophysics Data System (ADS)

    Duffey, K.; Wong, N.; Saykally, R.; Cohen, R. C.

    2012-12-01

    The transport of water molecules across vapor-liquid interfaces in the atmosphere is a crucial step in the formation and evolution of cloud droplets. Despite decades of study, the effects of solutes on the mechanism and rate of evaporation and condensation remain poorly characterized. The present work aims to determine the effect of atmospherically-relevant solutes on the evaporation rate of water. In our experiments, we create a train of micron-sized droplets and measure their temperature via Raman thermometry as they undergo evaporation without condensation. Analysis of the cooling rate yields the evaporation coefficient (γ). Previous work has shown that inorganic salts have little effect on γ, with surface-adsorbing anions causing a slight reduction in the coefficient from that measured for pure water. Organic acids are ubiquitous in aqueous aerosol and have been shown to disrupt the surface structure of water. Here we describe measurements of the evaporation rate of acetic acid solutions, showing that acetic acid reduces γ to a larger extent than inorganic ions, and that γ decreases with increasing acetic acid concentration.

  7. Crystal structure of febuxostat-acetic acid (1/1).

    PubMed

    Wu, Min; Hu, Xiu-Rong; Gu, Jian-Ming; Tang, Gu-Ping

    2015-05-01

    The asymmetric unit of the title compound [systematic name: 2-(3-cyano-4-iso-butyl-oxyphen-yl)-4-methyl-thia-zole-5-carb-oxy-lic acid-acetic acid (1/1)], C16H16N2O3S·CH3COOH, contains a febuxostat mol-ecule and an acetic acid mol-ecule. In the febuxostat mol-ecule, the thia-zole ring is nearly coplanar with the benzene ring [dihedral angle = 3.24 (2)°]. In the crystal, the febuxostat and acetic acid mol-ecules are linked by O-H⋯O, O-H⋯N hydrogen bonds and weak C-H⋯O hydrogen bonds, forming supra-molecular chains propagating along the b-axis direction. π-π stacking is observed between nearly parallel thia-zole and benzene rings of adjacent mol-ecules; the centroid-to-centroid distances are 3.8064 (17) and 3.9296 (17) Å.

  8. Bacillus spp. produce antibacterial activities against lactic acid bacteria that contaminate fuel ethanol plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lactic acid bacteria (LAB) frequently contaminate commercial fuel ethanol fermentations, reducing yields and decreasing profitability of biofuel production. Microorganisms from environmental sources in different geographic regions of Thailand were tested for antibacterial activity against LAB. Fou...

  9. Leguminose green juice as an efficient nutrient for l(+)-lactic acid production.

    PubMed

    Dietz, Donna; Schneider, Roland; Papendiek, Franka; Venus, Joachim

    2016-10-20

    Lactic acid is one of the most important building blocks for the production of bioplastic. Many investigations have been conducted to reduce the lactic acid production costs. In this work, the focus was put on the application of legume pressed juice or green juice as nutrient source. The pressed juice was utilized directly without prior pre-treatment and sterilization. Using two different alfalfa green juices and a clover green juice from two different harvest years as sole nutrients, non-sterile fermentations were performed at 52°C and pH 6.0 with a thermotolerant strain Bacillus coagulans AT107. The results showed that alfalfa green juices generally were more suitable for high lactic acid production than clover green juices, presumably due to the higher nitrogen content. A final titer of 98.8g/L after 30h with l(+)-lactic acid purity of >99% was obtained.

  10. Chemical synthesis of lactic acid from cellulose catalysed by lead(II) ions in water.

    PubMed

    Wang, Yanliang; Deng, Weiping; Wang, Binju; Zhang, Qinghong; Wan, Xiaoyue; Tang, Zhenchen; Wang, Ye; Zhu, Chun; Cao, Zexing; Wang, Guichang; Wan, Huilin

    2013-01-01

    The direct transformation of cellulose, which is the main component of lignocellulosic biomass, into building-block chemicals is the key to establishing biomass-based sustainable chemical processes. Only limited successes have been achieved for such transformations under mild conditions. Here we report the simple and efficient chemocatalytic conversion of cellulose in water in the presence of dilute lead(II) ions, into lactic acid, which is a high-value chemical used for the production of fine chemicals and biodegradable plastics. The lactic acid yield from microcrystalline cellulose and several lignocellulose-based raw biomasses is >60% at 463 K. Both theoretical and experimental studies suggest that lead(II) in combination with water catalyses a series of cascading steps for lactic acid formation, including the isomerization of glucose formed via the hydrolysis of cellulose into fructose, the selective cleavage of the C3-C4 bond of fructose to trioses and the selective conversion of trioses into lactic acid.

  11. Rheological behavior of poly(lactic acid)/synthetic mica nanocomposites.

    PubMed

    Souza, D H S; Andrade, C T; Dias, M L

    2013-04-01

    Poly(lactic acid) nanocomposites were prepared with three synthetic fluoromicas in a twin-screw extruder. Sodium and two organomodified synthetic fluoromicas at different compositions were used. The effect of mica type and composition on the rheological behavior of the nanocomposites was evaluated. The sodium fluoromica did not have a significant effect on the poly(lactic acid) rheological properties, while addition of the organophilic micas to poly(lactic acid) has a strong effect on the rheology, showing a pronounced shear thinning behavior. The dynamic rheological studies revealed that the nanocomposites with organomica have a higher viscosity and more pronounced elastic properties than neat poly(lactic acid). Both storage and loss moduli increased with mica content.

  12. Lactic acid production from Cellobiose and xylose by engineered Saccharomyces cerevisiae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Efficient and rapid production of value-added chemicals from lignocellulosic biomass is an important step towards a sustainable society. Lactic acid, used for synthesizing the bioplastic polylactide, has been produced by microbial fermentation using primarily glucose. Lignocellulosic hydrolysates co...

  13. Recombinant lactobacillus for fermentation of xylose to lactic acid and lactate

    DOEpatents

    Picataggio, Stephen K.; Zhang, Min; Franden, Mary Ann; Mc Millan, James D.; Finkelstein, Mark

    1998-01-01

    A recombinant Lactobacillus MONT4 is provided which has been genetically engineered with xylose isomerase and xylulokinase genes from Lactobacillus pentosus to impart to the Lactobacillus MONT4 the ability to ferment lignocellulosic biomass containing xylose to lactic acid.

  14. 16 years research on lactic acid production with yeast - ready for the market?

    PubMed

    Sauer, Michael; Porro, Danilo; Mattanovich, Diethard; Branduardi, Paola

    2010-01-01

    The use of plastic produced from non-renewable resources constitutes a major environmental problem of the modern society. Polylactide polymers (PLA) have recently gained enormous attention as one possible substitution of petroleum derived polymers. A prerequisite for high quality PLA production is the provision of optically pure lactic acid, which cannot be obtained by chemical synthesis in an economical way. Microbial fermentation is therefore the commercial option to obtain lactic acid as monomer for PLA production. However, one major economic hurdle for commercial lactic acid production as basis for PLA is the costly separation procedure, which is needed to recover and purify the product from the fermentation broth. Yeasts, such as Saccharomyces cerevisiae (bakers yeast) offer themselves as production organisms because they can tolerate low pH and grow on mineral media what eases the purification of the acid. However, naturally yeasts do not produce lactic acid. By metabolic engineering, ethanol was exchanged with lactic acid as end product of fermentation. A vast amount of effort has been invested into the development of yeasts for lactic acid production since the first paper on this topic by Dequin and Barre appeared 1994. Now yeasts are very close to industrial exploitation - here we summarize the developments in this field.

  15. Extracellular protease derived from lactic acid bacteria stimulates the fermentative lactic acid production from the by-products of rice as a biomass refinery function.

    PubMed

    Watanabe, Masanori; Techapun, Charin; Kuntiya, Ampin; Leksawasdi, Noppol; Seesuriyachan, Phisit; Chaiyaso, Thanongsak; Takenaka, Shinji; Maeda, Isamu; Koyama, Masahiro; Nakamura, Kozo

    2017-02-01

    A lactic acid producing bacterium, Lactobacillus rhamnosus M-23, newly isolated from a rice washing drainage storage tank was found to produce l-(+)-lactic acid from a non-sterilized mixture of rice washing drainage and rice bran without any additions of nutrients under the simultaneous saccharification and fermentation (SSF) process. This strain has the ability to utilize the non-sterilized rice washing drainage and rice bran as a source of carbohydrate, saccharifying enzymes and nutrients for lactic acid production. Observation of extracellular protease activity in SSF culture broth showed that a higher protease activity was present in strain M-23 than in other isolated lactic acid producing bacteria (LABs). To investigate the structural changes of solid particles of rice washing drainage throughout LAB cultivation, scanning electron microscopic (SEM) observation and Fourier transform infrared-spectroscopy (FT-IR) analysis were performed. The results of the SEM observation showed that the surface material could be removed from solid particles of rice washing drainage treated by culture broth (supernatant) of strain M-23, thus exposing the crystal structure of the starch particle surface. The results of the FT-IR analysis revealed that the specific transmittance decrease of the CC and CO stretching and OH group of the solid particles of the rice washing drainage were highly correlated with the produced lactic acid concentration and extracellular protease activity, respectively. These results demonstrate the high lactic acid producing ability of strain M-23 from a non-sterilized mixture of rice washing drainage and rice bran under the SSF condition due to the removal of proteinaceous material and exposure of the starch particle surface by extracellular protease.

  16. Production of D-lactic acid in a continuous membrane integrated fermentation reactor by genetically modified Saccharomyces cerevisiae: enhancement in D-lactic acid carbon yield.

    PubMed

    Mimitsuka, Takashi; Sawai, Kenji; Kobayashi, Koji; Tsukada, Takeshi; Takeuchi, Norihiro; Yamada, Katsushige; Ogino, Hiroyasu; Yonehara, Tetsu

    2015-01-01

    Poly d-lactic acid is an important polymer because it improves the thermostability of poly l-lactic acid by stereo complex formation. To demonstrate potency of continuous fermentation using a membrane-integrated fermentation reactor (MFR) system, continuous fermentation using genetically modified Saccharomyces cerevisiae which produces d-lactic acid was performed at the low pH and microaerobic conditions. d-Lactic acid continuous fermentation using the MFR system by genetically modified yeast increased production rate by 11-fold compared with batch fermentation. In addition, the carbon yield of d-lactic acid in continuous fermentation was improved to 74.6 ± 2.3% compared to 39.0 ± 1.7% with batch fermentation. This dramatic improvement in carbon yield could not be explained by a reduction in carbon consumption to form cells compared to batch fermentation. Further detailed analysis at batch fermentation revealed that the carbon yield increased to 76.8% at late stationary phase. S. cerevisiae, which exhibits the Crabtree-positive effect, demonstrated significant changes in metabolic activities at low sugar concentrations (Rossignol et al., Yeast, 20, 1369-1385, 2003). Moreover, lactate-producing S. cerevisiae requires ATP supplied not only from the glycolytic pathway but also from the TCA cycle (van Maris et al., Appl. Environ. Microbiol., 70, 2898-2905, 2004). Our finding was revealed that continuous fermentation, which can maintain the conditions of both a low sugar concentration and air supply, results in Crabtree-positive and lactate-producing S. cerevisiae for suitable conditions of d-lactic acid production with respect to redox balance and ATP generation because of releasing the yeast from the Crabtree effect.

  17. 40 CFR 721.10448 - Acetic acid, hydroxy- methoxy-, methyl ester, reaction products with substituted alkylamine...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... ester, reaction products with substituted alkylamine (generic). 721.10448 Section 721.10448 Protection... Acetic acid, hydroxy- methoxy-, methyl ester, reaction products with substituted alkylamine (generic). (a... generically as acetic acid, hydroxymethoxy-, methyl ester, reaction products with substituted alkylamine...

  18. 40 CFR 721.10448 - Acetic acid, hydroxy- methoxy-, methylester, reaction products with substituted alkylamine...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-, methylester, reaction products with substituted alkylamine (generic). 721.10448 Section 721.10448 Protection... Acetic acid, hydroxy- methoxy-, methylester, reaction products with substituted alkylamine (generic). (a... generically as acetic acid, hydroxymethoxy-, methyl ester, reaction products with substituted alkylamine...

  19. Dichloroacetate improves immune dysfunction caused by tumor-secreted lactic acid and increases antitumor immunoreactivity.

    PubMed

    Ohashi, Toshimitsu; Akazawa, Takashi; Aoki, Mitsuhiro; Kuze, Bunya; Mizuta, Keisuke; Ito, Yatsuji; Inoue, Norimitsu

    2013-09-01

    The activation of oncogenic signaling pathways induces the reprogramming of glucose metabolism in tumor cells and increases lactic acid secretion into the tumor microenvironment. This is a well-known characteristic of tumor cells, termed the Warburg effect, and is a candidate target for antitumor therapy. Previous reports show that lactic acid secreted by tumor cells is a proinflammatory mediator that activates the IL-23/IL-17 pathway, thereby inducing inflammation, angiogenesis and tissue remodeling. Here, we show that lactic acid, or more specifically the acidification it causes, increases arginase I (ARG1) expression in macrophages to inhibit T-cell proliferation and activation. Accordingly, we hypothesized that counteraction of the immune effects by lactic acid might suppress tumor development. We show that dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinases, targets macrophages to suppress activation of the IL-23/IL-17 pathway and the expression of ARG1 by lactic acid. Furthermore, lactic acid-pretreated macrophages inhibited CD8+ T-cell proliferation, but CD8+ T-cell proliferation was restored when macrophages were pretreated with lactic acid and DCA. DCA treatment decreased ARG1 expression in tumor-infiltrating immune cells and increased the number of IFN-γ-producing CD8+ T cells and NK cells in tumor-bearing mouse spleen. Although DCA treatment alone did not suppress tumor growth, it increased antitumor immunotherapeutic activity of Poly(IC) in both CD8+ T cell- and NK cell-sensitive tumor models. Therefore, DCA acts not only on tumor cells to suppress glycolysis but also on immune cells to improve the immune status modulated by lactic acid and to increase the effectiveness of antitumor immunotherapy.

  20. Anaerobic lactic acid degradation during ensilage of whole crop maize inoculated with lactobacillus buchneri inhibits yeast growth and improves aerobic stability

    PubMed

    Driehuis; Elferink; Spoelstra

    1999-10-01

    Aerobic deterioration of silages is initiated by (facultative) aerobic micro-organisms, usually yeasts, that oxidize the preserving organic acids. In this study, a Lactobacillus buchneri strain isolated from maize silage was evaluated for its potential as a bacterial inoculant that enhances aerobic stability of silages. In four experiments, chopped whole crop maize (30-43% dry matter (DM)) was inoculated with Lact. buchneri and ensiled in laboratory silos. Uninoculated silages served as controls. Analysis of silages treated with Lact. buchneri at levels of 103-106 cfu g-1 after about 3 months of anaerobic storage showedthat acetic acid and 1-propanol contents increased with inoculum levels above 104 cfu g-1,whereas lactic acid decreased. Propionic acid, silage pH and DM loss increased withinoculum levels above 105 cfu g-1. Time course experiments with maize inoculated with Lact. buchneri at 4 x 104-2 x 105 cfu g-1 showed that up to 7-14 d after ensiling, Lact. buchneri had no effect on silage characteristics. Thereafter, the lactic acid content of the inoculated silages declined and, simultaneously, acetic acid and, to a lesser extent, propionic acid and 1-propanol, accumulated. Inoculation reduced survival of yeasts during the anaerobic storage phase and inhibited yeast growth when the silage was exposed to O2, resulting in a substantial improvement in aerobic stability. The results indicate that the use of Lact. buchneri as a silage inoculant can enhance aerobic stability by inhibition of yeasts. The ability of the organism to ferment lactic acid to acetic acid appears to be an important underlying principle of this effect.

  1. Biofilm formation by lactic acid bacteria and resistance to environmental stress.

    PubMed

    Kubota, Hiromi; Senda, Shouko; Nomura, Nobuhiko; Tokuda, Hajime; Uchiyama, Hiroo

    2008-10-01

    We investigated the formation of biofilms by 3 type strains of lactic acid bacteria (LAB), Lactobacillus plantarum, Lactobacillus brevis and Lactobacillus fructivorans, as representatives of LAB that cause food deterioration or contamination. Lactobacillus plantarum subsp. plantarum JCM1149 and Lactobacillus brevis JCM1059 appeared to adhere and accumulate on glass cover slips. Lactobacillus fructivorans JCM1117 cells made thin cellophane-like biofilms, and most of the biofilm cells became longer than the planktonic cells. We tested the resistance of biofilm and planktonic L. plantarum subsp. plantarum JCM1149 cells to acetic acid and ethanol, which strongly inhibit the growth of bacteria and are important in food preservation. The biofilm cells were more resistant than the planktonic cells and the surfaces of the treated planktonic cells were badly damaged, whereas those of the biofilm cells were only slightly damaged. We isolated 43 LAB from onions and the biofolm cells of an isolate, L. plantarum M606 also had high resistance. These results demonstrate the significance of studying biofilms of LAB in the food industry.

  2. Coulometric titration of bases in acetic acid and acetonitrile media.

    PubMed

    Vajgand, V J; Mihajlović, R

    1969-09-01

    The working conditions and the results for coulometric titration of milligram amounts of some bases in 0.1M sodium perchlorate in a mixture of acetic acid and acetic anhydride (1:6), are given. Determinations were made both by coulometric back-titration or direct titration at the platinum anode. Back-titration was done in the catholyte, by coulometric titration of the excess of added perchloric acid. The titration end-point was detected photometrically with Crystal Violet as indicator. The direct titration of bases was done at the platinum anode, in the same electrolyte, to which hydroquinone was added as anode depolarizer and as the source of hydrogen ions, Malachite Green being used as indicator. Similarly, bases can be determined in acetonitrile if sodium perchlorate, hydroquinone and Malachite Green are added to the solvent. Errors are below 1 %, and the precision is satisfactory.

  3. Acetic acid pretreatment improves the hardness of cooked potato slices.

    PubMed

    Zhao, Wenlin; Shehzad, Hussain; Yan, Shoulei; Li, Jie; Wang, Qingzhang

    2017-08-01

    The effects of acetic acid pretreatment on the texture of cooked potato slices were investigated in this work. Potato slices were pretreated with acetic acid immersion (AAI), distilled water immersion (DWI), or no immersion (NI). Subsequently, the cell wall material of the pretreated samples was isolated and fractioned to evaluate changes in the monosaccharide content and molar mass (MM), and the hardness and microscopic structure of the potato slices in different pretreatments before and after cooking were determined. The results showed that the highest firmness was obtained with more intact structure of the cell wall for cooked potato slices with AAI pretreatment. Furthermore, the MM and sugar ratio demonstrated that the AAI pretreated potato slices contained a higher content of the small molecular polysaccharides of cell walls, especially in the hemicellulose fraction. This work may provide a reference for potato processing.

  4. Evaluation of sanitizing efficacy of acetic acid on Piper betle leaves and its effect on antioxidant properties.

    PubMed

    Singla, Richu; Ganguli, Abhijit; Ghosh, Moushumi; Sohal, Sapna

    2009-01-01

    The sanitizing efficacy of acetic acid and its effect on health beneficial properties of Piper betle leaves were determined. Betel leaves artificially inoculated with Aeromonas, Salmonella and Yersinia were subjected to organic acid (citric acid, acetic acid and lactic acid) treatment. Pathogen populations reduced by 4 log upon individual inoculation and up to 2 log in a mixed cocktail following treatment with 2% acetic acid during storage up to 20 h at 28 degrees C, indicating a residual antimicrobial effect on pathogen during storage. Antioxidant potential ethanolic extracts of both raw and treated P. betle leaves were assayed for free radical scavenging activities against 2,2-diphenyl-1-picryhydrazyl. Polyphenols, flavonoids and the reducing power of treated and untreated P. betle were also compared. No significant (P>0.05) changes were observed in antioxidant status; flavonoids, polyphenols and reducing power of treated betel leaves. Results indicate the feasibility of a simple intervention strategy for inactivating pathogens in edible leaves of P. betle.

  5. Cell wall structure and function in lactic acid bacteria

    PubMed Central

    2014-01-01

    The cell wall of Gram-positive bacteria is a complex assemblage of glycopolymers and proteins. It consists of a thick peptidoglycan sacculus that surrounds the cytoplasmic membrane and that is decorated with teichoic acids, polysaccharides, and proteins. It plays a major role in bacterial physiology since it maintains cell shape and integrity during growth and division; in addition, it acts as the interface between the bacterium and its environment. Lactic acid bacteria (LAB) are traditionally and widely used to ferment food, and they are also the subject of more and more research because of their potential health-related benefits. It is now recognized that understanding the composition, structure, and properties of LAB cell walls is a crucial part of developing technological and health applications using these bacteria. In this review, we examine the different components of the Gram-positive cell wall: peptidoglycan, teichoic acids, polysaccharides, and proteins. We present recent findings regarding the structure and function of these complex compounds, results that have emerged thanks to the tandem development of structural analysis and whole genome sequencing. Although general structures and biosynthesis pathways are conserved among Gram-positive bacteria, studies have revealed that LAB cell walls demonstrate unique properties; these studies have yielded some notable, fundamental, and novel findings. Given the potential of this research to contribute to future applied strategies, in our discussion of the role played by cell wall components in LAB physiology, we pay special attention to the mechanisms controlling bacterial autolysis, bacterial sensitivity to bacteriophages and the mechanisms underlying interactions between probiotic bacteria and their hosts. PMID:25186919

  6. Determination of plasma lactic acid concentration and specific activity using high-performance liquid chromatography.

    PubMed

    Bleiberg, B; Steinberg, J J; Katz, S D; Wexler, J; LeJemtel, T

    1991-08-23

    Assessment of lactate metabolism is of particular interest during exercise and in disease states such as diabetes, shock, and absorptive abnormalities of short-chain fatty acids by the colon. We describe an analytical method that introduces radio-active tracers and high-performance liquid chromatography (HPLC) to simultaneously analyze concentrations and specific activities (SAs) of plasma lactate. The HPLC conditions included separation on a reversed-phase column (octadecylsilane) and an isocratic buffer (30% acetonitrile in water). [3H]Acetate served as an internal standard. Lactate and acetate were extracted from plasma samples with diethyl ether following a pH adjustment to less than 1.0 and back-extracted into a hydrophilic phase with sodium carbonate (2 mM, pH greater than 10.0). Lactate is detected in the ultraviolet range (242 and 320 nm) by derivatization with alpha-bromoacetophenone. Control plasma samples were studied after an overnight fast for precision and analytical recovery. Calibration curves were linear in the range 0.18-6.0 mM (r = 0.92). The precision was 3% and the analytical recovery was 87%. The detection limit of the method was 36 pmol. Determination of lactate metabolism was performed in a patient with chronic congestive heart failure who was administered primed-continuous L-[U-14C]lactate (10 microCi bolus and 0.3 microCi/min continuously) during a 60-min rest period. Mean arterial lactate concentration and SA were 1.69 +/- 0.2 mM and 253.8 +/- 22 dpm/mumol, respectively. Systemic lactate turnover was 25.65 mumol/kg per min. Lactic acid systemic turnover, organ uptake and release rates can be accurately determined by isocratic HPLC.

  7. Core Fluxome and Metafluxome of Lactic Acid Bacteria under Simulated Cocoa Pulp Fermentation Conditions

    PubMed Central

    Adler, Philipp; Bolten, Christoph Josef; Dohnt, Katrin; Hansen, Carl Erik

    2013-01-01

    In the present work, simulated cocoa fermentation was investigated at the level of metabolic pathway fluxes (fluxome) of lactic acid bacteria (LAB), which are typically found in the microbial consortium known to convert nutrients from the cocoa pulp into organic acids. A comprehensive 13C labeling approach allowed to quantify carbon fluxes during simulated cocoa fermentation by (i) parallel 13C studies with [13C6]glucose, [1,2-13C2]glucose, and [13C6]fructose, respectively, (ii) gas chromatography-mass spectrometry (GC/MS) analysis of secreted acetate and lactate, (iii) stoichiometric profiling, and (iv) isotopomer modeling for flux calculation. The study of several strains of L. fermentum and L. plantarum revealed major differences in their fluxes. The L. fermentum strains channeled only a small amount (4 to 6%) of fructose into central metabolism, i.e., the phosphoketolase pathway, whereas only L. fermentum NCC 575 used fructose to form mannitol. In contrast, L. plantarum strains exhibited a high glycolytic flux. All strains differed in acetate flux, which originated from fractions of citrate (25 to 80%) and corresponding amounts of glucose and fructose. Subsequent, metafluxome studies with consortia of different L. fermentum and L. plantarum strains indicated a dominant (96%) contribution of L. fermentum NCC 575 to the overall flux in the microbial community, a scenario that was not observed for the other strains. This highlights the idea that individual LAB strains vary in their metabolic contribution to the overall fermentation process and opens up new routes toward streamlined starter cultures. L. fermentum NCC 575 might be one candidate due to its superior performance in flux activity. PMID:23851099

  8. Acetic acid enhances endurance capacity of exercise-trained mice by increasing skeletal muscle oxidative properties.

    PubMed

    Pan, Jeong Hoon; Kim, Jun Ho; Kim, Hyung Min; Lee, Eui Seop; Shin, Dong-Hoon; Kim, Seongpil; Shin, Minkyeong; Kim, Sang Ho; Lee, Jin Hyup; Kim, Young Jun

    2015-01-01

    Acetic acid has been shown to promote glycogen replenishment in skeletal muscle during exercise training. In this study, we investigated the effects of acetic acid on endurance capacity and muscle oxidative metabolism in the exercise training using in vivo mice model. In exercised mice, acetic acid induced a significant increase in endurance capacity accompanying a reduction in visceral adipose depots. Serum levels of non-esterified fatty acid and urea nitrogen were significantly lower in acetic acid-fed mice in the exercised mice. Importantly, in the mice, acetic acid significantly increased the muscle expression of key enzymes involved in fatty acid oxidation and glycolytic-to-oxidative fiber-type transformation. Taken together, these findings suggest that acetic acid improves endurance exercise capacity by promoting muscle oxidative properties, in part through the AMPK-mediated fatty acid oxidation and provide an important basis for the application of acetic acid as a major component of novel ergogenic aids.

  9. First Acetic Acid Survey with CARMA in Hot Molecular Cores

    NASA Astrophysics Data System (ADS)

    Shiao, Y.-S. Jerry; Looney, Leslie W.; Remijan, Anthony J.; Snyder, Lewis E.; Friedel, Douglas N.

    2010-06-01

    Acetic acid (CH3COOH) has been detected mainly in hot molecular cores where the distribution between oxygen (O) and nitrogen (N) containing molecular species is cospatial within the telescope beam. Previous work has presumed that similar cores with cospatial O and N species may be an indicator for detecting acetic acid. However, does this presumption hold as higher spatial resolution observations of large O- and N-containing molecules become available? As the number of detected acetic acid sources is still low, more observations are needed to support this postulate. In this paper, we report the first acetic acid survey conducted with the Combined Array for Research in Millimeter-wave Astronomy at 3 mm wavelengths toward G19.61-0.23, G29.96-0.02, and IRAS 16293-2422. We have successfully detected CH3COOH via two transitions toward G19.61-0.23 and tentatively confirmed the detection toward IRAS 16293-2422 A. The determined column density of CH3COOH is 2.0(1.0) × 1016 cm-2 and the abundance ratio of CH3COOH to methyl formate (HCOOCH3) is 2.2(0.1) × 10-1 toward G19.61-0.23. Toward IRAS 16293 A, the determined column density of CH3COOH is ~1.6 × 1015 cm-2 and the abundance ratio of CH3COOH to methyl formate (HCOOCH3) is ~1.0 × 10-1, both of which are consistent with abundance ratios determined toward other hot cores. Finally, we model all known line emission in our passband to determine physical conditions in the regions and introduce a new metric to better reveal weak spectral features that are blended with stronger lines or that may be near the 1σ-2σ detection limit.

  10. Characterization of the spoilage lactic acid bacteria in "sliced vacuum-packed cooked ham".

    PubMed

    Kalschne, Daneysa Lahis; Womer, Rute; Mattana, Ademir; Sarmento, Cleonice Mendes Pereira; Colla, Luciane Maria; Colla, Eliane

    2015-03-01

    The lactic acid bacteria are involved with food fermentation and in such cases with food spoilage. Considering the need to reduce the lactic acid bacteria growth in meat products, the aim of this work was to enumerated and investigated the lactic acid bacteria present on sliced vacuum-packed cooked ham stored at 4 °C and 8 °C for 45 days by phenotypic and molecular techniques. The quantification showed that the lactic acid bacteria were present from the first day with mean count of 1.98 log cfu/g for the four batches analyzed. The lactic acid bacteria grew rapidly on the samples, and plate counts around 7.59 log cfu/g and 8.25 log cfu/g were detected after 45 days of storage at 4 °C and 8 °C, respectively; storage temperatures studied showed significant influence on the microorganism in study growth. The predominant lactic acid bacteria associated with the spoilage samples at one day of storage includes Lactobacillus sp., the phenotypic overlap Leuconostoc / Weissella sp. and Enterococcus sp. At 45 days of storage at 4 and 8 °C the mainly specie was Lactobacillus curvatus , following by Lactobacillus sakei and Leuconostoc mesentereoides ; the Enterococcus sp. was not present in the samples.

  11. Isolation of alkaliphilic bacteria for production of high optically pure L-(+)-lactic acid.

    PubMed

    Yokaryo, Hiroto; Tokiwa, Yutaka

    2014-01-01

    Lactic acid bacteria that grow under alkaline conditions (pH 10) were isolated from various sources in Okinawa (Japan). These alkali-tolerant and alkaliphilic bacteria were classified as follows: Microbacterium sp. (1 strain), Enterococcus spp. (9 strains), Alkalibacterium spp. (3 strains), Exiguobacterium spp. (5 strains), Oceanobacillus spp. (3 strains) and Bacillus spp. (7 strains) by 16S rRNA gene sequencing. By fermentation, many strains were able to convert glucose into mainly L-(+)-lactic acid of high optical purity in alkaline broth. This result indicated that valuable L-(+)-lactic acid-producing bacteria could be isolated efficiently by screening under alkaline conditions. Six strains were selected and their ability to produce lactic acid at different initial pH was compared. Enterococcus casseliflavus strain 79w3 gave the highest lactic acid concentration. Lactic acid concentration and productivity were 103 g L(-1) (optical purity of 99.5% as L-isomer) and 2.2 g L(-1) h(-1), respectively when 129 g L(-1) of glucose was used by batch fermentation.

  12. Enhancement of L(+)-Lactic Acid Production of Immobilized Rhizopus Oryzae Implanted by Ion Beams

    NASA Astrophysics Data System (ADS)

    Fan, Yonghong; Yang, Yingge; Zheng, Zhiming; Li, Wen; Wang, Peng; Yao, Liming; Yu, Zengliang

    2008-02-01

    Immobilized Rhizopus oryzae culturing may be a solution to the inhibited production of L(+)-lactic acid in submerged fermentation, which is caused by aggregated mycelia floc. In the present study, a R. oryzae mutant (RL6041) with a 90% conversion rate of glucose into L-lactic acid was obtained by N+ implantation under the optimized conditions of a beam energy of 15 keV and a dose of 2.6 × 1015 ions/cm2. Using polyurethane foam as the immobilization matrix, the optimal L-lactic acid production conditions were determined as 4 mm polyurethane foam, 150 r/min, 50 g/L ~ 80 g/L of initial glucose, 38°C and pH 6.0. 15-cycle repeated productions of L-lactic acid by immobilized RL6041 were performed under the optimized culturing conditions and over 80% of the glucose was converted into L-lactic acid in 30 hours on average. The results show that immobilized RL6041 is a promising candidate for continuous L-lactic acid production.

  13. Characterization of the spoilage lactic acid bacteria in “sliced vacuum-packed cooked ham”

    PubMed Central

    Kalschne, Daneysa Lahis; Womer, Rute; Mattana, Ademir; Sarmento, Cleonice Mendes Pereira; Colla, Luciane Maria; Colla, Eliane

    2015-01-01

    The lactic acid bacteria are involved with food fermentation and in such cases with food spoilage. Considering the need to reduce the lactic acid bacteria growth in meat products, the aim of this work was to enumerated and investigated the lactic acid bacteria present on sliced vacuum-packed cooked ham stored at 4 °C and 8 °C for 45 days by phenotypic and molecular techniques. The quantification showed that the lactic acid bacteria were present from the first day with mean count of 1.98 log cfu/g for the four batches analyzed. The lactic acid bacteria grew rapidly on the samples, and plate counts around 7.59 log cfu/g and 8.25 log cfu/g were detected after 45 days of storage at 4 °C and 8 °C, respectively; storage temperatures studied showed significant influence on the microorganism in study growth. The predominant lactic acid bacteria associated with the spoilage samples at one day of storage includes Lactobacillus sp., the phenotypic overlap Leuconostoc / Weissella sp. and Enterococcus sp. At 45 days of storage at 4 and 8 °C the mainly specie was Lactobacillus curvatus , following by Lactobacillus sakei and Leuconostoc mesentereoides ; the Enterococcus sp. was not present in the samples. PMID:26221105

  14. Production of optically pure D-lactic acid from brown rice using metabolically engineered Lactobacillus plantarum.

    PubMed

    Okano, Kenji; Hama, Shinji; Kihara, Maki; Noda, Hideo; Tanaka, Tsutomu; Kondo, Akihiko

    2017-03-01

    Simultaneous saccharification and fermentation (SSF) of D-lactic acid was performed using brown rice as both a substrate and a nutrient source. An engineered Lactobacillus plantarum NCIMB 8826 strain, in which the ʟ-lactate dehydrogenase gene was disrupted, produced 97.7 g/L D-lactic acid from 20% (w/v) brown rice without any nutrient supplementation. However, a significant amount of glucose remained unconsumed and the yield of lactic acid was as low as 0.75 (g/g-glucose contained in brown rice). Interestingly, the glucose consumption was significantly improved by adapting L. plantarum cells to the low-pH condition during the early stage of SSF (8-17 h). As a result, 117.1 g/L D-lactic acid was produced with a high yield of 0.93 and an optical purity of 99.6% after 144 h of fermentation. SSF experiments were repeatedly performed for ten times and D-lactic acid was stably produced using recycled cells (118.4-129.8 g/L). On average, D-lactic acid was produced with a volumetric productivity of 2.18 g/L/h over 48 h.

  15. Lactic acid production from cellobiose and xylose by engineered Saccharomyces cerevisiae.

    PubMed

    Turner, Timothy L; Zhang, Guo-Chang; Oh, Eun Joong; Subramaniam, Vijay; Adiputra, Andrew; Subramaniam, Vimal; Skory, Christopher D; Jang, Ji Yeon; Yu, Byung Jo; Park, In; Jin, Yong-Su

    2016-05-01

    Efficient and rapid production of value-added chemicals from lignocellulosic biomass is an important step toward a sustainable society. Lactic acid, used for synthesizing the bioplastic polylactide, has been produced by microbial fermentation using primarily glucose. Lignocellulosic hydrolysates contain high concentrations of cellobiose and xylose. Here, we constructed a recombinant Saccharomyces cerevisiae strain capable of fermenting cellobiose and xylose into lactic acid. Specifically, genes (cdt-1, gh1-1, XYL1, XYL2, XYL3, and ldhA) coding for cellobiose transporter, β-glucosidase, xylose reductase, xylitol dehydrogenase, xylulokinase, and lactate dehydrogenase were integrated into the S. cerevisiae chromosomes. The resulting strain produced lactic acid from cellobiose or xylose with high yields. When fermenting a cellulosic sugar mixture containing 10 g/L glucose, 40 g/L xylose, and 80 g/L cellobiose, the engineered strain produced 83 g/L of lactic acid with a yield of 0.66 g lactic acid/g sugar (66% theoretical maximum). This study demonstrates initial steps toward the feasibility of sustainable production of lactic acid from lignocellulosic sugars by engineered yeast.

  16. Efficient production of L-lactic acid by Crabtree-negative yeast Candida boidinii.

    PubMed

    Osawa, Fumi; Fujii, Toshio; Nishida, Takehisa; Tada, Nobuki; Ohnishi, Toru; Kobayashi, Osamu; Komeda, Toshihiro; Yoshida, Satoshi

    2009-09-01

    Industrial production of L-lactic acid, which in polymerized form as poly-lactic acid is widely used as a biodegradable plastic, has been attracting world-wide attention. By genetic engineering we constructed a strain of the Crabtree-negative yeast Candida boidinii that efficiently produced a large amount of L-lactic acid. The alcohol fermentation pathway of C. boidinii was altered by disruption of the PDC1 gene encoding pyruvate decarboxylase, resulting in an ethanol production that was reduced to 17% of the wild-type strain. The alcohol fermentation pathway of the PDC1 deletion strain was then successfully utilized for the synthesis of L-lactic acid by placing the bovine L-lactate dehydrogenase-encoding gene under the control of the PDC1 promoter by targeted integration. Optimizing the conditions for batch culture in a 5 l jar-fermenter resulted in an L-lactic acid production reaching 85.9 g/l within 48 h. This productivity (1.79 g/l/h) is the highest thus far reported for L-lactic acid-producing yeasts.

  17. Effect of fermentation conditions on L-lactic acid production from soybean straw hydrolysate.

    PubMed

    Wang, Juan; Wang, Qunhui; Xu, Zhong; Zhang, Wenyu; Xiang, Juan

    2015-01-01

    Four types of straw, namely, soybean, wheat, corn, and rice, were investigated for use in lactic acid production. These straws were mainly composed of cellulose, hemicellulose, and lignin. After pretreatment with ammonia, the cellulose content increased, whereas the hemicellulose and lignin contents decreased. Analytical results also showed that the liquid enzymatic hydrolysates were primarily composed of glucose, xylose, and cellobiose. Preliminary experiments showed that a higher lactic acid concentration could be obtained from the wheat and soybean straw. However, soybean straw was chosen as the substrate for lactic acid production owing to its high protein content. The maximum lactic acid yield (0.8 g/g) and lactic acid productivity (0.61 g/(l/h)) were obtained with an initial reducing sugar concentration of 35 g/l at 30°C when using Lactobacillus casei (10% inoculum) for a 42 h fermentation period. Thus, the experimental results demonstrated the feasibility of using a soybean straw enzymatic hydrolysate as a substrate for lactic acid production.

  18. Kefir immobilized on corn grains as biocatalyst for lactic acid fermentation and sourdough bread making.

    PubMed

    Plessas, Stavros; Alexopoulos, Athanasios; Bekatorou, Argyro; Bezirtzoglou, Eugenia

    2012-12-01

    The natural mixed culture kefir was immobilized on boiled corn grains to produce an efficient biocatalyst for lactic acid fermentation with direct applications in food production, such as sourdough bread making. The immobilized biocatalyst was initially evaluated for its efficiency for lactic acid production by fermentation of cheese whey at various temperatures. The immobilized cells increased the fermentation rate and enhanced lactic acid production compared to free kefir cells. Maximum lactic acid yield (68.8 g/100 g) and lactic acid productivity (12.6 g/L per day) were obtained during fermentation by immobilized cells at 37 °C. The immobilized biocatalyst was then assessed as culture for sourdough bread making. The produced sourdough breads had satisfactory specific loaf volumes and good sensory characteristics. Specifically, bread made by addition of 60% w/w sourdough containing kefir immobilized on corn was more resistant regarding mould spoilage (appearance during the 11(th) day), probably due to higher lactic acid produced (2.86 g/Kg of bread) compared to the control samples. The sourdough breads made with the immobilized biocatalyst had aroma profiles similar to that of the control samples as shown by headspace SPME GC-MS analysis.

  19. Laboratory evaluation of lactic acid on attraction of Culex spp. (Diptera: Culicidae).

    PubMed

    Allan, Sandra A; Bernier, Ulrich R; Kline, Daniel L

    2010-12-01

    The role of lactic acid was evaluated for attraction of Culex nigripalpus, Culex quinquefasciatus, Culex tarsalis, and Aedes aegypti in the laboratory using a dual-port olfactometer. When lactic acid was combined with chicken odor, attraction was increased for Cx. quinquefasciatus compared to chicken odor alone but not for Cx. nigripalpus, Cx. tarsalis, and Ae. aegypti. Lactic acid combined with hand odor did not change attraction of Cx. tarsalis and Ae. aegypti but decreased attraction of Cx. nigripalpus and Cx. quinquefasciatus. The addition of lactic acid to CO(2) increased attraction of Ae. aegypti and Cx. quinquefasciatus but reduced attraction of Cx. nigripalpus and Cx. tarsalis. Use of commercial lactic acid baits with CO(2) resulted in a similar trend except for Cx. nigripalpus which showed no difference. A blend of lactic acid, acetone, and dimethyl disulfide was attractive to Ae. aegypti (63.4%) but elicited low responses by all Culex spp. (1.3-26.8%). Addition of the blend to CO(2) increased attraction of Ae. aegypti and Cx. quinquefasciatus but reduced attraction of Cx. nigripalpus and Cx. tarsalis. The mixture of compounds plus CO(2) was as attractive as a hand for Cx. quinquefasciatus, Cx. tarsalis, and Ae. aegypti.

  20. Kinetic modeling of lactic acid production from batch submerged fermentation of cheese whey

    SciTech Connect

    Tango, M.S.A.; Ghaly, A.E.

    1999-12-01

    A kinetic model for the production of lactic acid through batch submerged fermentation of cheese whey using Lactobacillus helveticus was developed. The model accounts for the effect of substrate limitation, substrate inhibition, lactic acid inhibition, maintenance energy and cell death on the cell growth, substrate utilization, and lactic acid production during the fermentation process. The model was evaluated using experimental data from Tango and Ghaly (1999). The predicted results obtained from the model compared well with experimental (R{sup 2} = 0.92--0.98). The model was also used to investigate the effect of the initial substrate concentration on the lag period, fermentation time, specific growth rate, and cell productivity during batch fermentation. The maximum specific growth rate ({micro}{sub m}), the saturation constant (K{sub S}), the substrate inhibition constant (K{sub IS}), and the lactic acid inhibition constant (K{sub IP}) were found to be 0.25h{sup {minus}1}, 0.9 g/L, 250.0 g/L, and 60.0 g/L, respectively. High initial lactose concentration in cheese whey reduced both the specific growth rate and substrate utilization rate due to the substrate inhibition phenomenon. The maximum lactic acid production occurred at about 100 g/L initial lactose concentration after 40 h of fermentation. The maximum lactic acid concentration above which Lactobacillus helveticus did not grow was found to be 80.0 g/L.

  1. Opportunities to overcome the current limitations and challenges for efficient microbial production of optically pure lactic acid.

    PubMed

    Abdel-Rahman, Mohamed Ali; Sonomoto, Kenji

    2016-10-20

    There has been growing interest in the microbial production of optically pure lactic acid due to the increased demand for lactic acid-derived environmentally friendly products, for example biodegradable plastic (poly-lactic acid), as an alternative to petroleum-derived materials. To maximize the market uptake of these products, their cost should be competitive and this could be achieved by decreasing the production cost of the raw material, that is, lactic acid. It is of great importance to isolate and develop robust and highly efficient microbial lactic acid producers. Alongside the fermentative substrate and concentration, the yield and productivity of lactic acid are key parameters and major factors in determining the final production cost of lactic acid. In this review, we will discuss the current limitations and challenges for cost-efficient microbial production of optically pure lactic acid. The main obstacles to effective fermentation are the use of food resources, indirect utilization of polymeric sugars, sensitivity to inhibitory compounds released during biomass treatments, substrate inhibition, decreased lactic acid yield and productivity, inefficient utilization of mixed sugars, end product inhibition, increased use of neutralizing agents, contamination problems, and decreased optical purity of lactic acid. Furthermore, opportunities to address and overcome these limitations, either by fermentation technology or metabolic engineering approaches, will be introduced and discussed.

  2. Probiotic lactic acid bacteria detoxify N-nitrosodimethylamine.

    PubMed

    Nowak, Adriana; Kuberski, Sławomir; Libudzisz, Zdzisława

    2014-01-01

    Humans can be exposed to N-nitroso compounds (NOCs) due to many environmental sources, as well as endogenous formation. The main nitrosamine found in food products and also synthesised in vivo by intestinal microbiota is N-nitrosodimethylamine (NDMA). It can cause cancer of the stomach, kidney and colon. The effect of four probiotic Lactobacillus strains on NDMA was studied under different culture conditions (24 h in MRS, 168 h in modified MRS N, and 168 h in phosphate buffer). HPLC and GC-TEA methods were used for NDMA determination in supernatants. The influence of lactic acid bacteria on NDMA genotoxicity was investigated by means of the comet assay. Additionally, the effect of NDMA (2-100 µg ml⁻¹) on the growth and survival of the probiotic strains was studied. The results indicate that the bacteria decreased NDMA concentration by up to 50%, depending on the culture conditions, time of incubation, NDMA concentration, pH and bacterial strain. Lb. brevis 0945 lowered the concentration and genotoxicity of NDMA most effectively by up to 50%. This could be due to either adsorption or metabolism. The growth and survival of the bacteria was not affected by any of the tested NDMA concentrations.

  3. Molecular characterization of lactic acid populations associated with wine spoilage.

    PubMed

    Beneduce, L; Spano, G; Vernile, A; Tarantino, D; Massa, S

    2004-01-01

    We have investigated the prevalence of spoilage lactic acid bacteria (LAB) in table wines produced in the Apulia region. The occurrence of LAB was evaluated in wines produced with low sulphur dioxide doses and not supplemented with selected malolactic starters such as Oenococcus oeni. About 150 strains were isolated from wine must and a molecular characterization was performed using PCR-based techniques. Most of the strains analysed belonged to Lactobacillus plantarum species. However, some of the strains were identified as Pediococcus damnosus and Leuconostoc sp. The amplified fragments of Pediococcus damnosus were cloned and sequenced. The coding sequence was highly homologous to that of the ropy plasmid confirming that the isolated strain was a ropy(+) Pediococcus damnosus. In all the samples analysed, the final must pH value reached was relatively high (from 3.78 to 3.90). The high pH values had probably negatively influenced (counteracted) the activity of sulphur dioxide added, allowing proliferation of spoilage wine microorganisms.

  4. Adhesion Properties of Lactic Acid Bacteria on Intestinal Mucin

    PubMed Central

    Nishiyama, Keita; Sugiyama, Makoto; Mukai, Takao

    2016-01-01

    Lactic acid bacteria (LAB) are Gram-positive bacteria that are natural inhabitants of the gastrointestinal (GI) tracts of mammals, including humans. Since Mechnikov first proposed that yogurt could prevent intestinal putrefaction and aging, the beneficial effects of LAB have been widely demonstrated. The region between the duodenum and the terminal of the ileum is the primary region colonized by LAB, particularly the Lactobacillus species, and this region is covered by a mucus layer composed mainly of mucin-type glycoproteins. The mucus layer plays a role in protecting the intestinal epithelial cells against damage, but is also considered to be critical for the adhesion of Lactobacillus in the GI tract. Consequently, the adhesion exhibited by lactobacilli on mucin has attracted attention as one of the critical factors contributing to the persistent beneficial effects of Lactobacillus in a constantly changing intestinal environment. Thus, understanding the interactions between Lactobacillus and mucin is crucial for elucidating the survival strategies of LAB in the GI tract. This review highlights the properties of the interactions between Lactobacillus and mucin, while concomitantly considering the structure of the GI tract from a histochemical perspective. PMID:27681930

  5. Isolation and characterisation of lactic acid bacteria from donkey milk.

    PubMed

    Soto Del Rio, Maria de Los Dolores; Andrighetto, Christian; Dalmasso, Alessandra; Lombardi, Angiolella; Civera, Tiziana; Bottero, Maria Teresa

    2016-08-01

    During the last years the interest in donkey milk has increased significantly mainly because of its compelling functional elements. Even if the composition and nutritional properties of donkey milk are known, its microbiota is less studied. This Research Communication aimed to provide a comprehensive characterisation of the lactic acid bacteria in raw donkey milk. RAPD-PCR assay combined with 16S rDNA sequencing analysis were used to describe the microbial diversity of several donkey farms in the North West part of Italy. The more frequently detected species were: Lactobacillus paracasei, Lactococcus lactis and Carnobacterium maltaromaticum. Less abundant genera were Leuconostoc, Enterococcus and Streptococcus. The yeast Kluyveromyces marxianus was also isolated. The bacterial and biotype distribution notably diverged among the farms. Several of the found species, not previously detected in donkey milk, could have an important probiotic activity and biotechnological potential. This study represents an important insight to the ample diversity of the microorganisms present in the highly selective ecosystem of raw donkey milk.

  6. Perspectives of engineering lactic acid bacteria for biotechnological polyol production.

    PubMed

    Monedero, Vicente; Pérez-Martínez, Gaspar; Yebra, María J

    2010-04-01

    Polyols are sugar alcohols largely used as sweeteners and they are claimed to have several health-promoting effects (low-caloric, low-glycemic, low-insulinemic, anticariogenic, and prebiotic). While at present chemical synthesis is the only strategy able to assure the polyol market demand, the biotechnological production of polyols has been implemented in yeasts, fungi, and bacteria. Lactic acid bacteria (LAB) are a group of microorganisms particularly suited for polyol production as they display a fermentative metabolism associated with an important redox modulation and a limited biosynthetic capacity. In addition, LAB participate in food fermentation processes, where in situ production of polyols during fermentation may be useful in the development of novel functional foods. Here, we review the polyol production by LAB, focusing on metabolic engineering strategies aimed to redirect sugar fermentation pathways towards the synthesis of biotechnologically important sugar alcohols such as sorbitol, mannitol, and xylitol. Furthermore, possible approaches are presented for engineering new fermentation routes in LAB for production of arabitol, ribitol, and erythritol.

  7. Genome level analysis of bacteriocins of lactic acid bacteria.

    PubMed

    Singh, Neetigyata Pratap; Tiwari, Abhay; Bansal, Ankiti; Thakur, Shruti; Sharma, Garima; Gabrani, Reema

    2015-06-01

    Bacteriocins are antimicrobial peptides which are ribosomally synthesized by mainly all bacterial species. LABs (lactic acid bacteria) are a diverse group of bacteria that include around 20 genera of various species. Though LABs have a tremendous potential for production of anti-microbial peptides, this group of bacteria is still underexplored for bacteriocins. To study the diversity among bacteriocin encoding clusters and the putative bacteriocin precursors, genome mining was performed on 20 different species of LAB not reported to be bacteriocin producers. The phylogenetic tree of gyrB, rpoB, and 16S rRNA were constructed using MEGA6 software to analyze the diversity among strains. Putative bacteriocins operons identified were found to be diverse and were further characterized on the basis of physiochemical properties and the secondary structure. The presence of at least two cysteine residues in most of the observed putative bacteriocins leads to disulphide bond formation and provide stability. Our data suggests that LABs are prolific source of low molecular weight non modified peptides.

  8. Heat Capacity of Poly(L-lactic acid)

    NASA Astrophysics Data System (ADS)

    Pyda, Marek; Bopp, C. Bopp Richard C.; Richard, C.; Wunderlich, Bernhard

    2002-03-01

    The heat capacity of poly(L-lactic acid) (PLA) is reported from 5-520 K from standard differential scanning calorimetry (DSC), temperature modulated DSC (TMDSC), and adiabatic calorimetry. The semicrystalline PLA has a melting endotherm between 418 and 432 K, with variable heats of fusion, depending on thermal history. The thermodynamic heat of fusion is 6.15 kJ/mol. The heat capacity is linked to its group vibrational spectrum and the skeletal vibrations described by the Tarasov equation (theta parameters 574 and 52 K, N = 9). Calculated and experimental heat capacities agree to ±3compares within ±0.5contributions of other polymers with the same constituent groups. The glass transition temperature of liquid PLA is at 333 K with a change in heat capacity of about 41 J/(K mol). With these results, the enthalpy, entropy, and Gibbs function were obtained. For semicrystalline samples one can then discuss the crystallinity changes with temperature, the question of a rigid-amorphous fraction, and the reversible melting. --- Supported by NSF, Polymers Program, DMR-9703692, and the Div. of Mat. Sci., BES, DOE at ORNL, managed by UT-Batelle, LLC, for the U.S. Department of Energy, under contract number DOE-AC05-00OR22725.

  9. Lactic acid bacteria in dried vegetables and spices.

    PubMed

    Säde, Elina; Lassila, Elisa; Björkroth, Johanna

    2016-02-01

    Spices and dried vegetable seasonings are potential sources of bacterial contamination for foods. However, little is known about lactic acid bacteria (LAB) in spices and dried vegetables, even though certain LAB may cause food spoilage. In this study, we enumerated LAB in 104 spices and dried vegetables products aimed for the food manufacturing industry. The products were obtained from a spice wholesaler operating in Finland, and were sampled during a one-year period. We picked isolates (n = 343) for species identification based on numerical analysis of their ribotyping patterns and comparing them with the corresponding patterns of LAB type strains. We found LAB at levels >2 log CFU/g in 68 (65%) of the samples, with the highest counts detected from dried onion products and garlic powder with counts ranging from 4.24 to 6.64 log CFU/g. The LAB identified were predominantly Weissella spp. (61%) and Pediococcus spp. (15%) with Weissella confusa, Weissella cibaria, Weissella paramesenteroides, Pediococcus acidilactici and Pediococcus pentosaceus being the species identified. Other species identified belonged to the genera of Enterococcus spp. (8%), Leuconostoc spp. (6%) and Lactobacillus spp. (2%). Among the LAB identified, Leuconostoc citreum, Leuconostoc mesenteroides and W. confusa have been associated with food spoilage. Our findings suggest that spices and dried vegetables are potential sources of LAB contamination in the food industry.

  10. A gene network engineering platform for lactic acid bacteria.

    PubMed

    Kong, Wentao; Kapuganti, Venkata S; Lu, Ting

    2016-02-29

    Recent developments in synthetic biology have positioned lactic acid bacteria (LAB) as a major class of cellular chassis for applications. To achieve the full potential of LAB, one fundamental prerequisite is the capacity for rapid engineering of complex gene networks, such as natural biosynthetic pathways and multicomponent synthetic circuits, into which cellular functions are encoded. Here, we present a synthetic biology platform for rapid construction and optimization of large-scale gene networks in LAB. The platform involves a copy-controlled shuttle for hosting target networks and two associated strategies that enable efficient genetic editing and phenotypic validation. By using a nisin biosynthesis pathway and its variants as examples, we demonstrated multiplex, continuous editing of small DNA parts, such as ribosome-binding sites, as well as efficient manipulation of large building blocks such as genes and operons. To showcase the platform, we applied it to expand the phenotypic diversity of the nisin pathway by quickly generating a library of 63 pathway variants. We further demonstrated its utility by altering the regulatory topology of the nisin pathway for constitutive bacteriocin biosynthesis. This work demonstrates the feasibility of rapid and advanced engineering of gene networks in LAB, fostering their applications in biomedicine and other areas.

  11. 21 CFR 175.350 - Vinyl acetate/crotonic acid copolymer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Vinyl acetate/crotonic acid copolymer. 175.350... COATINGS Substances for Use as Components of Coatings § 175.350 Vinyl acetate/crotonic acid copolymer. A copolymer of vinyl acetate and crotonic acid may be safely used as a coating or as a component of a...

  12. 40 CFR 180.1258 - Acetic acid; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Acetic acid; exemption from the... Exemptions From Tolerances § 180.1258 Acetic acid; exemption from the requirement of a tolerance. An... acetic acid when used as a preservative on post-harvest agricultural commodities intended for animal...

  13. 75 FR 52269 - Acetic Acid Ethenyl Ester, Polymer With Oxirane; Tolerance Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-25

    ...-2010-0429; FRL-8841-2] Acetic Acid Ethenyl Ester, Polymer With Oxirane; Tolerance Exemption AGENCY... from the requirement of a tolerance for residues of acetic acid ethenyl ester, polymer with oxirane... permissible level for residues of acetic acid ethenyl ester, polymer with oxirane on food or feed...

  14. 75 FR 40736 - Acetic Acid; Exemption from the Requirement of a Tolerance

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-14

    ... AGENCY 40 CFR Part 180 Acetic Acid; Exemption from the Requirement of a Tolerance AGENCY: Environmental... for acetic acid by establishing an exemption from the requirement of a tolerance for residues of acetic acid, also known as vinegar in or on all food crops resulting from unintentional spray and...

  15. Industrial application of selected lactic acid bacteria isolated from local semolinas for typical sourdough bread production.

    PubMed

    Corona, Onofrio; Alfonzo, Antonio; Ventimiglia, Giusi; Nasca, Anna; Francesca, Nicola; Martorana, Alessandra; Moschetti, Giancarlo; Settanni, Luca

    2016-10-01

    Four obligate heterofermentative lactic acid bacteria (LAB) strains (Weissella cibaria PON10030 and PON10032 and Leuconostoc citreum PON 10079 and PON10080) were tested as single strain starters, mono-species dual strain starters, and multiple strain starter for the preparation and propagation of sourdoughs for the production of a typical bread at industrial level. The kinetics of pH and TTA during the daily sourdough refreshments indicated a correct acidification process for all trials. The concentration of lactic and acetic acid increased consistently during fermentation. The resulting molar ratios between these two organic acids in the experimental trials were lower than those observed in the control trial. The microbiological investigation showed levels of approximately 10(9) CFU/mL in almost all sourdoughs and the comparison of the genetic polymorphisms of the dominating LAB with those of the pure cultures evidenced the persistence of the added strains over time. The resulting breads were evaluated for several quality parameters. The breads with the greatest height were obtained with the quadruple combination of leuconostocs and weissellas. The highest softness was registered for the breads obtained from fermentations performed by W. cibaria PON10032 alone and in combination. The different inocula influenced also the color, the void fraction, the cell density and the mean cell area of the breads. Different levels of acids, alcohols, aldehydes, esters, hydrocarbons, ketones, terpenes, furans and phenol were emitted by the breads. The sensory tests indicated the breads from the sourdoughs fermented with the seven LAB inocula as sweeter and less acidic than control breads and the breads from the trials with the highest complexity of LAB inoculums were those more appreciated by tasters. A multivariate approach found strong differences among the trials. In particular, control breads and the breads obtained with different starter LAB were quite distant and a more

  16. Indole-3-acetic acid in plant-microbe interactions.

    PubMed

    Duca, Daiana; Lorv, Janet; Patten, Cheryl L; Rose, David; Glick, Bernard R

    2014-07-01

    Indole-3-acetic acid (IAA) is an important phytohormone with the capacity to control plant development in both beneficial and deleterious ways. The ability to synthesize IAA is an attribute that many bacteria including both plant growth-promoters and phytopathogens possess. There are three main pathways through which IAA is synthesized; the indole-3-pyruvic acid, indole-3-acetamide and indole-3-acetonitrile pathways. This chapter reviews the factors that effect the production of this phytohormone, the role of IAA in bacterial physiology and in plant-microbe interactions including phytostimulation and phytopathogenesis.

  17. Animal Rennets as Sources of Dairy Lactic Acid Bacteria

    PubMed Central

    Cruciata, Margherita; Sannino, Ciro; Ercolini, Danilo; Scatassa, Maria L.; De Filippis, Francesca; Mancuso, Isabella; La Storia, Antonietta; Moschetti, Giancarlo

    2014-01-01

    The microbial composition of artisan and industrial animal rennet pastes was studied by using both culture-dependent and -independent approaches. Pyrosequencing targeting the 16S rRNA gene allowed to identify 361 operational taxonomic units (OTUs) to the genus/species level. Among lactic acid bacteria (LAB), Streptococcus thermophilus and some lactobacilli, mainly Lactobacillus crispatus and Lactobacillus reuteri, were the most abundant species, with differences among the samples. Twelve groups of microorganisms were targeted by viable plate counts revealing a dominance of mesophilic cocci. All rennets were able to acidify ultrahigh-temperature-processed (UHT) milk as shown by pH and total titratable acidity (TTA). Presumptive LAB isolated at the highest dilutions of acidified milks were phenotypically characterized, grouped, differentiated at the strain level by randomly amplified polymorphic DNA (RAPD)-PCR analysis, and subjected to 16S rRNA gene sequencing. Only 18 strains were clearly identified at the species level, as Enterococcus casseliflavus, Enterococcus faecium, Enterococcus faecalis, Enterococcus lactis, Lactobacillus delbrueckii, and Streptococcus thermophilus, while the other strains, all belonging to the genus Enterococcus, could not be allotted into any previously described species. The phylogenetic analysis showed that these strains might represent different unknown species. All strains were evaluated for their dairy technological performances. All isolates produced diacetyl, and 10 of them produced a rapid pH drop in milk, but only 3 isolates were also autolytic. This work showed that animal rennet pastes can be sources of LAB, mainly enterococci, that might contribute to the microbial diversity associated with dairy productions. PMID:24441167

  18. Animal rennets as sources of dairy lactic acid bacteria.

    PubMed

    Cruciata, Margherita; Sannino, Ciro; Ercolini, Danilo; Scatassa, Maria L; De Filippis, Francesca; Mancuso, Isabella; La Storia, Antonietta; Moschetti, Giancarlo; Settanni, Luca

    2014-04-01

    The microbial composition of artisan and industrial animal rennet pastes was studied by using both culture-dependent and -independent approaches. Pyrosequencing targeting the 16S rRNA gene allowed to identify 361 operational taxonomic units (OTUs) to the genus/species level. Among lactic acid bacteria (LAB), Streptococcus thermophilus and some lactobacilli, mainly Lactobacillus crispatus and Lactobacillus reuteri, were the most abundant species, with differences among the samples. Twelve groups of microorganisms were targeted by viable plate counts revealing a dominance of mesophilic cocci. All rennets were able to acidify ultrahigh-temperature-processed (UHT) milk as shown by pH and total titratable acidity (TTA). Presumptive LAB isolated at the highest dilutions of acidified milks were phenotypically characterized, grouped, differentiated at the strain level by randomly amplified polymorphic DNA (RAPD)-PCR analysis, and subjected to 16S rRNA gene sequencing. Only 18 strains were clearly identified at the species level, as Enterococcus casseliflavus, Enterococcus faecium, Enterococcus faecalis, Enterococcus lactis, Lactobacillus delbrueckii, and Streptococcus thermophilus, while the other strains, all belonging to the genus Enterococcus, could not be allotted into any previously described species. The phylogenetic analysis showed that these strains might represent different unknown species. All strains were evaluated for their dairy technological performances. All isolates produced diacetyl, and 10 of them produced a rapid pH drop in milk, but only 3 isolates were also autolytic. This work showed that animal rennet pastes can be sources of LAB, mainly enterococci, that might contribute to the microbial diversity associated with dairy productions.

  19. Electrospun poly(lactic acid) based conducting nanofibrous networks

    NASA Astrophysics Data System (ADS)

    Patra, S. N.; Bhattacharyya, D.; Ray, S.; Easteal, A. J.

    2009-08-01

    Multi-functionalised micro/nanostructures of conducting polymers in neat or blended forms have received much attention because of their unique properties and technological applications in electrical, magnetic and biomedical devices. Biopolymer-based conducting fibrous mats are of special interest for tissue engineering because they not only physically support tissue growth but also are electrically conductive, and thus are able to stimulate specific cell functions or trigger cell responses. They are effective for carrying current in biological environments and can thus be considered for delivering local electrical stimuli at the site of damaged tissue to promote wound healing. Electrospinning is an established way to process polymer solutions or melts into continuous fibres with diameter often in the nanometre range. This process primarily depends on a number of parameters, including the type of polymer, solution viscosity, polarity and surface tension of the solvent, electric field strength and the distance between the spinneret and the collector. The present research has included polyaniline (PANi) as the conducting polymer and poly(L-lactic acid) (PLLA) as the biopolymer. Dodecylbenzene sulphonic acid (DBSA) doped PANi and PLLA have been dissolved in a common solvent (mixtures of chloroform and dimethyl formamide (DMF)), and the solutions successfully electrospun. DMF enhanced the dielectric constant of the solvent, and tetra butyl ammonium bromide (TBAB) was used as an additive to increase the conductivity of the solution. DBSA-doped PANi/PLLA mat exhibits an almost bead-free network of nanofibres that have extraordinarily smooth surface and diameters in the range 75 to 100 nm.

  20. Regulation of the expression and activity of glucose and lactic acid metabolism-related genes by protein kinase C in skeletal muscle cells.

    PubMed

    Otake, Sho; Kobayashi, Masaki; Narumi, Katsuya; Sasaki, Shotaro; Kikutani, Yurika; Furugen, Ayako; Watanabe, Meguho; Takahashi, Natsuko; Ogura, Jiro; Yamaguchi, Hiroaki; Iseki, Ken

    2013-01-01

    Protein kinase C (PKC) modulators are very attractive therapeutic targets in cancer. Since most cancer cells display increased glycolysis, elucidations of the effects of PKC activation on glycolysis is necessary for the development of effective medicine. In the present study, to clarify the role of PKC in the regulation of glycolysis, we examined the effect of phorbol 12-myristate 13-acetate (PMA), a PKC activator, on the expression and activity of glucose and lactic acid metabolism-related genes in human rhabdomyosarcoma cells (RD cells). In parallel to increases in glucose uptake and mRNA levels of glucose transporters (GLUTs) induced by PMA treatment for 6 h, the hexokinase (HK) mRNA level and activity were also significantly increased in RD cells. On the other hand, a significant increase in lactate dehydrogenase (LDH) mRNA level and activity was seen when the cells were incubated with PMA for 24 h, but not for 6 or 12 h, and was associated with lactic acid production. These effects by PMA treatment were markedly suppressed by Bisindolylmaleimide (BIM), a PKC inhibitor. Furthermore, chetomin, a hypoxia-inducible factor 1 (HIF-1) inhibitor, completely abrogated the increment of LDH mRNA level and activity as well as monocarboxylate transporter (MCT) 4, a lactic acid efflux transporter. In conclusion, we found that HK and LDH activity induced by PKC activation was associated with the glucose uptake and lactic acid level and that LDH and MCT4 are modulated by a common factor, HIF-1.

  1. Change in the plasmid copy number in acetic acid bacteria in response to growth phase and acetic acid concentration.

    PubMed

    Akasaka, Naoki; Astuti, Wiwik; Ishii, Yuri; Hidese, Ryota; Sakoda, Hisao; Fujiwara, Shinsuke

    2015-06-01

    Plasmids pGE1 (2.5 kb), pGE2 (7.2 kb), and pGE3 (5.5 kb) were isolated from Gluconacetobacter europaeus KGMA0119, and sequence analyses revealed they harbored 3, 8, and 4 genes, respectively. Plasmid copy numbers (PCNs) were determined by real-time quantitative PCR at different stages of bacterial growth. When KGMA0119 was cultured in medium containing 0.4% ethanol and 0.5% acetic acid, PCN of pGE1 increased from 7 copies/genome in the logarithmic phase to a maximum of 12 copies/genome at the beginning of the stationary phase, before decreasing to 4 copies/genome in the late stationary phase. PCNs for pGE2 and pGE3 were maintained at 1-3 copies/genome during all phases of growth. Under a higher concentration of ethanol (3.2%) the PCN for pGE1 was slightly lower in all the growth stages, and those of pGE2 and pGE3 were unchanged. In the presence of 1.0% acetic acid, PCNs were higher for pGE1 (10 copies/genome) and pGE3 (6 copies/genome) during the logarithmic phase. Numbers for pGE2 did not change, indicating that pGE1 and pGE3 increase their PCNs in response to acetic acid. Plasmids pBE2 and pBE3 were constructed by ligating linearized pGE2 and pGE3 into pBR322. Both plasmids were replicable in Escherichia coli, Acetobacter pasteurianus and G. europaeus, highlighting their suitability as vectors for acetic acid bacteria.

  2. Effect of Lactic Acid Etching on Bonding Effectiveness of Orthodontic Bracket after Water Storage

    PubMed Central

    Alsulaimani, Fahad F.

    2014-01-01

    Objective. To determine the effect of lactic acid at various concentrations on the shear bond strength of orthodontic brackets bonded with the resin adhesive system before and after water storage. Materials and Methods. Hundred extracted human premolars were divided into 5 treatment groups and etched for 30 seconds with one of the following agents: lactic acid solution with (A) 10%, (B) 20%, (C) 30%, and (D) 50%; group E, 37% phosphoric acid (control). Metal brackets were bonded using a Transbond XT. Bonding effectiveness was assessed by shear bond strength after 24 hours and 6 months of water storage at 37°C. The data were analyzed with 2-way analysis of variance and Tukey's Honestly Significant Difference (HSD) test (α = .001). Results. Lactic acid concentration and water storage resulted in significant differences for brackets bond strength (P < .001). 20% lactic acid had significantly higher mean bond strength values (SD) for all conditions: 24 hours [12.2 (.7) MPa] and 6 months [10.1 (.6) MPa] of water storage. 37% phosphoric acid had intermediate bond strength values for all conditions: 24 hours [8.2 (.6) MPa] and 6 months [6.2 (.6) MPa] of water storage. Also, there were differences in bond strength between storage time, with a reduction in values from 24 hours and 6 months for all experimental groups (P < .001). Conclusion. Lactic acid could be used in place of phosphoric acid as an enamel etchant for bonding of orthodontic brackets. PMID:25006465

  3. Lactic acid bacteria: promising supplements for enhancing the biological activities of kombucha.

    PubMed

    Nguyen, Nguyen Khoi; Dong, Ngan Thi Ngoc; Nguyen, Huong Thuy; Le, Phu Hong

    2015-01-01

    Kombucha is sweetened black tea that is fermented by a symbiosis of bacteria and yeast embedded within a cellulose membrane. It is considered a health drink in many countries because it is a rich source of vitamins and may have other health benefits. It has previously been reported that adding lactic acid bacteria (Lactobacillus) strains to kombucha can enhance its biological functions, but in that study only lactic acid bacteria isolated from kefir grains were tested. There are many other natural sources of lactic acid bacteria. In this study, we examined the effects of lactic acid bacteria from various fermented Vietnamese food sources (pickled cabbage, kefir and kombucha) on kombucha's three main biological functions: glucuronic acid production, antibacterial activity and antioxidant ability. Glucuronic acid production was determined by high-performance liquid chromatography-mass spectrometry, antibacterial activity was assessed by the agar-well diffusion method and antioxidant ability was evaluated by determining the 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity. Four strains of food-borne pathogenic bacteria were used in our antibacterial experiments: Listeria monocytogenes ATCC 19111, Escherichia coli ATCC 8739, Salmonella typhimurium ATCC 14028 and Bacillus cereus ATCC 11778. Our findings showed that lactic acid bacteria strains isolated from kefir are superior to those from other sources for improving glucuronic acid production and enhancing the antibacterial and antioxidant activities of kombucha. This study illustrates the potential of Lactobacillus casei and Lactobacillus plantarum isolated from kefir as biosupplements for enhancing the bioactivities of kombucha.

  4. Activity of virgin coconut oil, lauric acid or monolaurin in combination with lactic acid against Staphylococcus aureus.

    PubMed

    Tangwatcharin, Pussadee; Khopaibool, Prapaporn

    2012-07-01

    The objective of this study was to investigate the in vitro activities of virgin coconut oil, lauric acid and monolaurin in combination with lactic acid against two strains of Staphylococcus aureus, ATCC 25923 and an isolate from a pig carcass, by determination of Fractional Bactericidal Concentration Index (FBCI), time-kill method, as well as scanning and transmission electron microscopy. Minimum bactericidal concentrations (MBC) of lauric acid, monolaurin and lactic acid were 3.2 mg/ml, 0.1 mg/ml and 0.4% (v/v), respectively. The effects of lauric acid + lactic acid and monolaurin + lactic acid combinations were synergistic against both strains, exhibiting FBCIs of 0.25 and 0.63, respectively. In time-kill studies, lauric acid and monolaurin + lactic acid combinations added at their minimum inhibitory concentrations produced a bactericidal effect. The induction of stress in non-stressed cells was dependent on the type and concentration of antimicrobial. This resulted in a loss and change of the cytoplasm and membrane in cells of the bacterium. In contrast, virgin coconut oil (10%) was not active against S. aureus. The bacterial counts found in pork loin treated with lauric acid and monolaurin alone were significantly higher (p <0.05) than those treated with both lipids in combination with lactic acid at sub-inhibitory concentrations. The color, odor and overall acceptability of the pork loins were adversely affected by treatment with the three lipids and lactic acid alone but when combinations of the agents were used the sensory quality was acceptable.

  5. Determination of gaseous formic acid and acetic acid by pulsed ultraviolet photoacoustic spectroscopy

    SciTech Connect

    Cvijin, P.V.; Gilmore, D.A.; Atkinson, G.H.

    1988-07-01

    The quantitative determination of gaseous formic acid and acetic acid by photoacoustic spectroscopy (PAS) using pulsed laser excitation in the ultraviolet is reported. Instrumentation utilizing continuously tunable laser excitation in the 220-nm wavelength region is used to record time-resolved PA signals from samples of each acid. Detection limits of 140 ppbv for formic acid and 120 ppbv for acetic acid in dry nitrogen at one atmosphere total pressure are attained. Considerable background signal originating from atmospheric oxygen is found to impose limitations on the detection sensitive with air samples.

  6. Randomized clinical efficacy of superficial peeling with 85% lactic acid versus 70% glycolic acid*

    PubMed Central

    Prestes, Paula Souza; de Oliveira, Márcia Motta Maia; Leonardi, Gislaine Ricci

    2013-01-01

    BACKGROUND: Peeling is a procedure which aims to accelerate the process of skin exfoliation. OBJECTIVES Development of formulations containing lactic acid at 85% or glycolic acid at 70% and the evaluation of these formulations on clinical efficacy in reduction of fine wrinkles. METHODS Preliminary stability tests were carried out and an in vivo study was performed with three groups with 9 representatives each. One was the control group, which used only sunscreen; another one used lactic acid+sunscreen, and the last group used acid glycolic+sunscreen. Clinical efficacy was assessed with a CCD color microscope, through the digitization of images before and after treatment. The applications were carried out by a dermatologist, once a mont h every 30 days, during 3 months. The area with wrinkles was calculated by planimetry point counting, in accordance with Mandarin-de-Lacerda. RESULTS The formulations were stable in the visual and Ph evaluation. There was no improvement in the control group; for lactic acid, there was significant improvement after the second peeling application on the outer lateral area of the right eye and after the third application on the outer lateral area of the left eye. For the glycolic acid group, there was significant improvement in the outer lateral area of the left eye after the first application, and of the right eye region, after three applications. The formulations used must be kept under refrigeration and should be manipulated every 30 days. CONCLUSIONS Both peelings were effective in reducing fine wrinkles of the outer lateral eye area after three applications (p≤0.05%). It was observed that peeling efficacy in the external-lateral region of one eye might be different compared with that in skin of the external-lateral region of the other eye, relative to the speed of skin improvement. PMID:24474097

  7. Selective catalysis for cellulose conversion to lactic acid and other α-hydroxy acids.

    PubMed

    Dusselier, Michiel; Sels, Bert F

    2014-01-01

    This review discusses topical chemical routes and their catalysis for the conversion of cellulose, hexoses, and smaller carbohydrates to lactic acid and other useful α-hydroxy acids. Lactic acid is a top chemical opportunity from carbohydrate biomass as it not only features tremendous potential as a chemical platform molecule; it is also a common building block for commercially employed green solvents and near-commodity bio-plastics. Its current scale fermentative synthesis is sufficient, but it could be considered a bottleneck for a million ton scale breakthrough. Alternative chemical routes are therefore investigated using multifunctional, often heterogeneous, catalysis. Rather than summarizing yields and conditions, this review attempts to guide the reader through the complex reaction networks encountered when synthetic lactates from carbohydrate biomass are targeted. Detailed inspection of the cascade of reactions emphasizes the need for a selective retro-aldol activity in the catalyst. Recently unveiled catalytic routes towards other promising α-hydroxy acids such as glycolic acid, and vinyl and furyl glycolic acids are highlighted as well.

  8. Distinct effects of sorbic acid and acetic acid on the electrophysiology and metabolism of Bacillus subtilis.

    PubMed

    van Beilen, J W A; Teixeira de Mattos, M J; Hellingwerf, K J; Brul, S

    2014-10-01

    Sorbic acid and acetic acid are among the weak organic acid preservatives most commonly used to improve the microbiological stability of foods. They have similar pKa values, but sorbic acid is a far more potent preservative. Weak organic acids are most effective at low pH. Under these circumstances, they are assumed to diffuse across the membrane as neutral undissociated acids. We show here that the level of initial intracellular acidification depends on the concentration of undissociated acid and less on the nature of the acid. Recovery of the internal pH depends on the presence of an energy source, but acidification of the cytosol causes a decrease in glucose flux. Furthermore, sorbic acid is a more potent uncoupler of the membrane potential than acetic acid. Together these effects may also slow the rate of ATP synthesis significantly and may thus (partially) explain sorbic acid's effectiveness.

  9. High-efficiency l-lactic acid production by Rhizopus oryzae using a novel modified one-step fermentation strategy.

    PubMed

    Fu, Yong-Qian; Yin, Long-Fei; Zhu, Hua-Yue; Jiang, Ru

    2016-10-01

    In this study, lactic acid fermentation by Rhizopus oryzae was investigated using the two different fermentation strategies of one-step fermentation (OSF) and conventional fermentation (CF). Compared to CF, OSF reduced the demurrage of the production process and increased the production of lactic acid. However, the qp was significantly lower than during CF. Based on analysis of μ, qs and qp, a novel modified OSF strategy was proposed. This strategy aimed to achieve a high final concentration of lactic acid, and a high qp by R. oryzae. In this strategy, the maximum lactic acid concentration and productivity of the lactic acid production stage reached 158g/l and 5.45g/(lh), which were 177% and 366% higher, respectively, than the best results from CF. Importantly, the qp and yield did not decrease. This strategy is a convenient and economical method for l-lactic acid fermentation by R. oryzae.

  10. Overexpression of acetyl-CoA synthetase in Saccharomyces cerevisiae increases acetic acid tolerance.

    PubMed

    Ding, Jun; Holzwarth, Garrett; Penner, Michael H; Patton-Vogt, Jana; Bakalinsky, Alan T

    2015-01-01

    Acetic acid-mediated inhibition of the fermentation of lignocellulose-derived sugars impedes development of plant biomass as a source of renewable ethanol. In order to overcome this inhibition, the capacity of Saccharomyces cerevisiae to synthesize acetyl-CoA from acetic acid was increased by overexpressing ACS2 encoding acetyl-coenzyme A synthetase. Overexpression of ACS2 resulted in higher resistance to acetic acid as measured by an increased growth rate and shorter lag phase relative to a wild-type control strain, suggesting that Acs2-mediated consumption of acetic acid during fermentation contributes to acetic acid detoxification.

  11. Codominance of Lactobacillus plantarum and obligate heterofermentative lactic acid bacteria during sourdough fermentation.

    PubMed

    Ventimiglia, Giusi; Alfonzo, Antonio; Galluzzo, Paola; Corona, Onofrio; Francesca, Nicola; Caracappa, Santo; Moschetti, Giancarlo; Settanni, Luca

    2015-10-01

    Fifteen sourdoughs produced in western Sicily (southern Italy) were analysed by classical methods for their chemico-physical characteristics and the levels of lactic acid bacteria (LAB). pH and total titratable acidity (TTA) were mostly in the range commonly reported for similar products produced in Italy, but the fermentation quotient (FQ) of the majority of samples was above 4.0, due to the low concentration of acetic acid estimated by high performance liquid chromatography (HPLC). Specific counts of LAB showed levels higher than 10(8) CFU g(-1) for many samples. The colonies representing various morphologies were isolated and, after the differentiation based on phenotypic characteristics, divided into 10 groups. The most numerous group was composed of facultative heterofermentative isolates, indicating a relevance of this bacterial group during fermentation. The genetic analysis by randomly amplified polymorphic DNA (RAPD)-PCR, 16S rRNA gene sequencing and species-specific PCRs identified 33 strains as Lactobacillus plantarum, Lactobacillus curvatus and Lactobacillus graminis. Due to the consistent presence of L. plantarum, it was concluded that this species codominates with obligate heterofermentative LAB in sourdough production in this geographical area. In order to evaluate the performances at the basis of their fitness, the 29 L. plantarum strains were investigated for several technological traits. Twelve cultures showed good acidifying abilities in vitro and L. plantarum PON100148 produced the highest concentrations of organic acids. Eleven strains were positive for extracellular protease activity. Bacteriocin-like inhibitory substances (BLIS) production and antifungal activity was scored positive for several strains, included L. plantarum PON100148 which was selected as starter for experimental sourdough production. The characteristics of the sourdoughs and the resulting breads indicated that the best productions were obtained in presence of L

  12. Determination of tertiary amines and salts of organic acids in acetic acid by catalytic thermometric titration.

    PubMed

    Vajgand, V J; Gaál, F F

    1967-03-01

    A new method of determination of tertiary amines and salts of organic adds in acetic acid solution, to which about 2 % of water and 8% acetic anhydride are added, is described. After the equivalence point, the excess of perchloric acid catalyses the exothermic reaction of water with acetic anhydride. The end-point is determined from the graph of temperature against volume of added titrant. If a slightly soluble compound is produced during the titration, the precision of the new method is superior to that of the potentiometric method.

  13. Short communication: Conversion of lactose and whey into lactic acid by engineered yeast.

    PubMed

    Turner, Timothy L; Kim, Eunbee; Hwang, ChangHoon; Zhang, Guo-Chang; Liu, Jing-Jing; Jin, Yong-Su

    2017-01-01

    Lactose is often considered an unwanted and wasted byproduct, particularly lactose trapped in acid whey from yogurt production. But using specialized microbial fermentation, the surplus wasted acid whey could be converted into value-added chemicals. The baker's yeast Saccharomyces cerevisiae, which is commonly used for industrial fermentation, cannot natively ferment lactose. The present study describes how an engineered S. cerevisiae yeast was constructed to produce lactic acid from purified lactose, whey, or dairy milk. Lactic acid is an excellent proof-of-concept chemical to produce from lactose, because lactic acid has many food, pharmaceutical, and industrial uses, and over 250,000 t are produced for industrial use annually. To ferment the milk sugar lactose, a cellodextrin transporter (CDT-1, which also transports lactose) and a β-glucosidase (GH1-1, which also acts as a β-galactosidase) from Neurospora crassa were expressed in a S. cerevisiae strain. A heterologous lactate dehydrogenase (encoded by ldhA) from the fungus Rhizopus oryzae was integrated into the CDT-1/GH1-1-expressing strain of S. cerevisiae. As a result, the engineered strain was able to produce lactic acid from purified lactose, whey, and store-bought milk. A lactic acid yield of 0.358g/g of lactose was achieved from whey fermentation, providing an initial proof of concept for the production of value-added chemicals from excess industrial whey using engineered yeast.

  14. Rationale and Safety Assessment of a Novel Intravaginal Drug-Delivery System with Sustained DL-Lactic Acid Release, Intended for Long-Term Protection of the Vaginal Microbiome.

    PubMed

    Verstraelen, Hans; Vervaet, Chris; Remon, Jean-Paul

    2016-01-01

    Bacterial vaginosis is a prevalent state of dysbiosis of the vaginal microbiota with wide-ranging impact on human reproductive health. Based on recent insights in community ecology of the vaginal microbiome, we hypothesize that sustained vaginal DL-lactic acid enrichment will enhance the recruitment of lactobacilli, while counteracting bacterial vaginosis-associated bacteria. We therefore aimed to develop an intravaginal device that would be easy to insert and remove, while providing sustained DL-lactic acid release into the vaginal lumen. The final prototype selected is a vaginal ring matrix system consisting of a mixture of ethylene vinyl acetate and methacrylic acid-methyl methacrylate copolymer loaded with 150 mg DL-lactic acid with an L/D-lactic acid ratio of 1:1. Preclinical safety assessment was performed by use of the Slug Mucosal Irritation test, a non-vertebrate assay to evaluate vaginal mucosal irritation, which revealed no irritation. Clinical safety was evaluated in a phase I trial with six healthy nulliparous premenopausal volunteering women, with the investigational drug left in place for 7 days. Colposcopic monitoring according to the WHO/CONRAD guidelines for the evaluation of vaginal products, revealed no visible cervicovaginal mucosal changes. No adverse events related to the investigational product occurred. Total release from the intravaginal ring over 7 days was estimated through high performance liquid chromatography at 37.1 (standard deviation 0.9) mg DL-lactic acid. Semisolid lactic acid formulations have been studied to a limited extent in the past and typically consist of a large volume of excipients and very high doses of lactic acid, which is of major concern to mucosal safety. We have documented the feasability of enriching the vaginal environment with pure DL-lactic acid with a prototype intravaginal ring. Though the efficacy of this platform remains to be established possibly requiring further development, this approach may offer a

  15. Transport mechanism for L-lactic acid in human myocytes using human prototypic embryonal rhabdomyosarcoma cell line (RD cells).

    PubMed

    Kobayashi, Masaki; Fujita, Itaru; Itagaki, Shirou; Hirano, Takeshi; Iseki, Ken

    2005-07-01

    Monocarboxylate transporter (MCT), which cotransport L-lactic acid and protons across cell membranes, are important for regulation of muscle pH. However, it has not been demonstrated in detail whether MCT isoform contribute to the transport of L-lactic acid in skeletal muscle. The aim of this study was to characterize L-lactic acid transport using an human rhabdomyosarcoma (RD) cell line as a model of human skeletal muscle. mRNAs of MCT 1, 2 and 4 were found to be expressed in RD cells. The [14C] L-lactic acid uptake was concentration-dependent with a Km of 1.19 mM. This Km value was comparable to its Km values for MCT1 or MCT2. MCT1 mRNA was found to be present markedly greater than that MCT2. Therefore, MCT1 most probably acts on L-lactic acid uptake at RD cells. [14C] L-Lactic acid efflux in RD cells was inhibited by alpha-cyano-4-hydroxycinnamate (CHC) but not by butyric acid, a substrate of MCT1. Accordingly, MCT2 or MCT4 is responsible for L-lactic acid efflux by RD cells. MCT4 mRNA was found to be present significantly greater than that MCT2. We conclude that MCT1 is responsible for L-lactic acid uptake and L-lactic acid efflux is mediated by MCT4 in RD cells.

  16. Formation of biologically relevant carboxylic acids during the gamma irradiation of acetic acid

    NASA Technical Reports Server (NTRS)

    Negron-Mendoza, A.; Ponnamperuma, C.

    1976-01-01

    Irradiation of aqueous solutions of acetic acid with gamma rays produced several carboxylic acids in small yield. Their identification was based on the technique of gas chromatography combined with mass spectrometry. Some of these acids are Krebs Cycle intermediates. Their simultaneous formation in experiments simulating the primitive conditions on the earth suggests that metabolic pathways may have had their origin in prebiotic chemical processes.

  17. Production of L-lactic acid by Rhizopus oryzae using semicontinuous fermentation in bioreactor.

    PubMed

    Wu, Xuefeng; Jiang, Shaotong; Liu, Mo; Pan, Lijun; Zheng, Zhi; Luo, Shuizhong

    2011-04-01

    Semicontinuous fermentation using pellets of Rhizopus oryzae has been recognized as a promising technology for L-lactic acid production. In this work, semicontinuous fermentation of R. oryzae AS 3.819 for L-lactic acid production has been developed with high L-lactic acid yield and volumetric productivity. The effects of factors such as inoculations, CaCO₃ addition time, and temperature on L-lactic acid yield and R. oryzae morphology were researched in detail. The results showed that optimal fermentation conditions for the first cycle were: inoculation with 4% spore suspension, CaCO₃ added to the culture medium at the beginning of culture, and culture temperature of 32-34 °C. In orthogonal experiments, high L-lactic acid yield was achieved when the feeding medium was (g/l): glucose, 100; (NH₄)₂SO₄, 2; KH₂PO₄, 0.1; ZnSO₄·7H₂O, 0.33; MgSO₄·7H₂O, 0.15; CaCO₃, 50. Twenty cycles of semicontinuous fermentation were carried out in flask culture. L: -lactic acid yield was 78.75% for the first cycle and 80-90% for the repeated cycles; the activities of lactate dehydrogenases (LDH) were 7.2-9.2 U/mg; fermentation was completed in 24 h for each repeated cycle. In a 7-l magnetically stirred fermentor, semicontinuous fermentation lasted for 25 cycles using pellets of R. oryzae AS 3.819 under the optimal conditions determined from flask cultures. The final L-lactic acid concentration (LLAC) reached 103.7 g/l, and the volumetric productivity was 2.16 g/(l·h) for the first cycle; in the following 19 repeated cycles, the final LLAC reached 81-95 g/l, and the volumetric productivities were 3.40-3.85 g/(l·h).

  18. L: (+)-Lactic acid production from non-food carbohydrates by thermotolerant Bacillus coagulans.

    PubMed

    Ou, Mark S; Ingram, Lonnie O; Shanmugam, K T

    2011-05-01

    Lactic acid is used as an additive in foods, pharmaceuticals, and cosmetics, and is also an industrial chemical. Optically pure lactic acid is increasingly used as a renewable bio-based product to replace petroleum-based plastics. However, current production of lactic acid depends on carbohydrate feedstocks that have alternate uses as foods. The use of non-food feedstocks by current commercial biocatalysts is limited by inefficient pathways for pentose utilization. B. coagulans strain 36D1 is a thermotolerant bacterium that can grow and efficiently ferment pentoses using the pentose-phosphate pathway and all other sugar constituents of lignocellulosic biomass at 50°C and pH 5.0, conditions that also favor simultaneous enzymatic saccharification and fermentation (SSF) of cellulose. Using this bacterial biocatalyst, high levels (150-180 g l(-1)) of lactic acid were produced from xylose and glucose with minimal by-products in mineral salts medium. In a fed-batch SSF of crystalline cellulose with fungal enzymes and B. coagulans, lactic acid titer was 80 g l(-1) and the yield was close to 80%. These results demonstrate that B. coagulans can effectively ferment non-food carbohydrates from lignocellulose to L: (+)-lactic acid at sufficient concentrations for commercial application. The high temperature fermentation of pentoses and hexoses to lactic acid by B. coagulans has these additional advantages: reduction in cellulase loading in SSF of cellulose with a decrease in enzyme cost in the process and a reduction in contamination of large-scale fermentations.

  19. A novel fermentation pathway in an Escherichia coli mutant producing succinic acid, acetic acid, and ethanol.

    SciTech Connect

    Donnelly, M. I.; Millard, C. S.; Clark, D. P.; Chen, M. J.; Rathke, J. W.; Southern Illinois Univ.

    1998-04-01

    Escherichia coli strain NZN111, which is unable to grow fermentatively because of insertional inactivation of the genes encoding pyruvate: formate lyase and the fermentative lactate dehydrogenase, gave rise spontaneously to a chromosomal mutation that restored its ability to ferment glucose. The mutant strain, named AFP111, fermented glucose more slowly than did its wild-type ancestor, strain W1485, and generated a very different spectrum of products. AFP111 produced succinic acid, acetic acid, and ethanol in proportions of approx 2:1:1. Calculations of carbon and electron balances accounted fully for the observed products; 1 mol of glucose was converted to 1 mol of succinic acid and 0.5 mol each of acetic acid and ethanol. The data support the emergence in E.coli of a novel succinic acid:acetic acid:ethanol fermentation pathway.

  20. Antibiotic resistance of lactic acid bacteria isolated from Chinese yogurts.

    PubMed

    Zhou, N; Zhang, J X; Fan, M T; Wang, J; Guo, G; Wei, X Y

    2012-09-01

    The aim of this study was to evaluate the susceptibility of 43 strains of lactic acid bacteria, isolated from Chinese yogurts made in different geographical areas, to 11 antibiotics (ampicillin, penicillin G, roxithromycin, chloramphenicol, tetracycline, chlortetracycline, lincomycin, kanamycin, streptomycin, neomycin, and gentamycin). The 43 isolates (18 Lactobacillus bulgaricus and 25 Streptococcus thermophilus) were identified at species level and were typed by random amplified polymorphic DNA analysis. Thirty-five genotypically different strains were detected and their antimicrobial resistance to 11 antibiotics was determined using the agar dilution method. Widespread resistance to ampicillin, chloramphenicol, chlortetracycline, tetracyclines, lincomycin, streptomycin, neomycin, and gentamycin was found among the 35 strains tested. All of the Strep. thermophilus strains tested were susceptible to penicillin G and roxithromycin, whereas 23.5 and 64.7% of Lb. bulgaricus strains, respectively, were resistant. All of the Strep. thermophilus and Lb. bulgaricus strains were found to be resistant to kanamycin. The presence of the corresponding resistance genes in the resistant isolates was investigated through PCR, with the following genes detected: tet(M) in 1 Lb. bulgaricus and 2 Strep. thermophilus isolates, ant(6) in 2 Lb. bulgaricus and 2 Strep. thermophilus isolates, and aph(3')-IIIa in 5 Lb. bulgaricus and 2 Strep. thermophilus isolates. The main threat associated with these bacteria is that they may transfer resistance genes to pathogenic bacteria, which has been a major cause of concern to human and animal health. To our knowledge, the aph(3')-IIIa and ant(6) genes were found in Lb. bulgaricus and Strep. thermophilus for the first time. Further investigations are required to analyze whether the genes identified in Lb. bulgaricus and Strep. thermophilus isolates might be horizontally transferred to other species.

  1. Magnesium phenylphosphonate: a additive for poly(L-lactic acid)

    NASA Astrophysics Data System (ADS)

    Cai, Yan-Hua; Zhao, Li-Sha

    2017-03-01

    Developing a advanced additive to promote the crystallization of poly(L-lactic acid) (PLLA) is still one of the main challenges for application. Here, magnesium phenylphosphonate (MgP), as a heterogeneous nucleating agent, was prepared to investigate directly its influence on the crystallization behavior and thermal stability of PLLA via a combination of differential scanning calorimetry (DSC), x-ray diffraction (XRD), and thermogravimetric analysis (TGA). The relevant results, from measurements of non-isothermal crystallization, the glass transition temperature, and XRD after melt crystallization, revealed that the MgP had excellent acceleration effectiveness in the melt crystallization of PLLA, and PLLA–0.7% MgP exhibited the sharpest non-isothermal crystallization peak and the highest non-isothermal crystallization enthalpy, suggesting that 0.7 wt% MgP is the optimal concentration in the PLLA matrix. In addition, these measurements also indicated that the incorporation of MgP could not change the crystal form of PLLA, and the non-isothermal crystallization behavior of PLLA–0.7% MgP did not have a significant relationship with the set final melting temperature. The melting behavior after non-isothermal crystallization further confirmed the crystallization-promoting effect of MgP for PLLA, and the second heating rate significantly affected the melting behavior of PLLA–MgP samples, resulting from the effect of heating rate on formation of crystallites. Thermal stability measurement showed that the addition of MgP could not change the thermal decomposition behavior of the primary PLLA, though MgP exhibited completely different thermal decomposition behavior. Furthermore, the influence of MgP concentration on the thermal decomposition temperatures of PLLA–MgP samples is negligible.

  2. Interactions between Cooccurring Lactic Acid Bacteria in Honey Bee Hives.

    PubMed

    Rokop, Z P; Horton, M A; Newton, I L G

    2015-10-01

    In contrast to the honey bee gut, which is colonized by a few characteristic bacterial clades, the hive of the honey bee is home to a diverse array of microbes, including many lactic acid bacteria (LAB). In this study, we used culture, combined with sequencing, to sample the LAB communities found across hive environments. Specifically, we sought to use network analysis to identify microbial hubs sharing nearly identical operational taxonomic units, evidence which may indicate cooccurrence of bacteria between environments. In the process, we identified interactions between noncore bacterial members (Fructobacillus and Lactobacillaceae) and honey bee-specific "core" members. Both Fructobacillus and Lactobacillaceae colonize brood cells, bee bread, and nectar and may serve the role of pioneering species, establishing an environment conducive to the inoculation by honey bee core bacteria. Coculture assays showed that these noncore bacterial members promote the growth of honey bee-specific bacterial species. Specifically, Fructobacillus by-products in spent medium supported the growth of the Firm-5 honey bee-specific clade in vitro. Metabolic characterization of Fructobacillus using carbohydrate utilization assays revealed that this strain is capable of utilizing the simple sugars fructose and glucose, as well as the complex plant carbohydrate lignin. We tested Fructobacillus for antibiotic sensitivity and found that this bacterium, which may be important for establishment of the microbiome, is sensitive to the commonly used antibiotic tetracycline. Our results point to the possible significance of "noncore" and environmental microbial community members in the modulation of honey bee microbiome dynamics and suggest that tetracycline use by beekeepers should be limited.

  3. Effect of acetic acid on citric acid fermentation in an integrated citric acid-methane fermentation process.

    PubMed

    Xu, Jian; Chen, Yang-Qiu; Zhang, Hong-Jian; Tang, Lei; Wang, Ke; Zhang, Jian-Hua; Chen, Xu-Sheng; Mao, Zhong-Gui

    2014-09-01

    An integrated citric acid-methane fermentation process was proposed to solve the problem of extraction wastewater in citric acid fermentation process. Extraction wastewater was treated by anaerobic digestion and then recycled for the next batch of citric acid fermentation to eliminate wastewater discharge and reduce water resource consumption. Acetic acid as an intermediate product of methane fermentation was present in anaerobic digestion effluent. In this study, the effect of acetic acid on citric acid fermentation was investigated and results showed that lower concentration of acetic acid could promote Aspergillus niger growth and citric acid production. 5-Cyano-2,3-ditolyl tetrazolium chloride (CTC) staining was used to quantify the activity of A. niger cells, and the results suggested that when acetic acid concentration was above 8 mM at initial pH 4.5, the morphology of A. niger became uneven and the part of the cells' activity was significantly reduced, thereby resulting in deceasing of citric acid production. Effects of acetic acid on citric acid fermentation, as influenced by initial pH and cell number in inocula, were also examined. The result indicated that inhibition by acetic acid increased as initial pH declined and was rarely influenced by cell number in inocula.

  4. Phenotypic and genotypic characterization of lactic acid bacteria isolated from raw goat milk and effect of farming practices on the dominant species of lactic acid bacteria.

    PubMed

    Tormo, Hélène; Ali Haimoud Lekhal, Djamila; Roques, C

    2015-10-01

    Lactic acid bacteria, in particular Lactococcus lactis, play a decisive role in the cheese making process and more particularly in lactic cheeses which are primarily produced on goat dairy farms. The objective of this study was therefore to identify the main lactic acid bacteria found in raw goats' milk from three different regions in France and evaluate if certain farming practices have an effect on the distribution of species of lactic acid bacteria in the various milk samples. Identification at genus or species level was carried out using phenotypic tests and genotypic methods including repetitive element REP-PCR, species-specific PCR and 16S rRNA gene sequencing. The distribution of the main bacterial species in the milk samples varied depending on farms and their characteristics. Out of the 146 strains identified, L. lactis was the dominant species (60% of strains), followed by Enterococcus (38%) of which Enterococcus faecalis and Enterococcus faecium. Within the species L. lactis, L. lactis subsp lactis was detected more frequently than L. lactis subsp cremoris (74% vs. 26%). The predominance of L. lactis subsp cremoris was linked to geographical area studied. It appears that the animals' environment plays a role in the balance between the dominance of L. lactis and enterococci in raw goats' milk. The separation between the milking parlor and the goat shed (vs no separation) and only straw in the bedding (vs straw and hay) seems to promote L. lactis in the milk (vs enterococci).

  5. Genetic engineering of Candida utilis yeast for efficient production of L-lactic acid.

    PubMed

    Ikushima, Shigehito; Fujii, Toshio; Kobayashi, Osamu; Yoshida, Satoshi; Yoshida, Aruto

    2009-08-01

    Polylactic acid is receiving increasing attention as a renewable alternative for conventional petroleum-based plastics. In the present study, we constructed a metabolically-engineered Candida utilis strain that produces L-lactic acid with the highest efficiency yet reported in yeasts. Initially, the gene encoding pyruvate decarboxylase (CuPDC1) was identified, followed by four CuPDC1 disruption events in order to obtain a null mutant that produced little ethanol (a by-product of L-lactic acid). Two copies of the L-lactate dehydrogenase (L-LDH) gene derived from Bos taurus under the control of the CuPDC1 promoter were then integrated into the genome of the CuPdc1-null deletant. The resulting strain produced 103.3 g/l of L-lactic acid from 108.7 g/l of glucose in 33 h, representing a 95.1% conversion. The maximum production rate of L-lactic acid was 4.9 g/l/h. The optical purity of the L-lactic acid was found to be more than 99.9% e.e.

  6. Glucose metabolic flux distribution of Lactobacillus amylophilus during lactic acid production using kitchen waste saccharified solution.

    PubMed

    Liu, Jianguo; Wang, Qunhui; Zou, Hui; Liu, Yingying; Wang, Juan; Gan, Kemin; Xiang, Juan

    2013-11-01

    The (13) C isotope tracer method was used to investigate the glucose metabolic flux distribution and regulation in Lactobacillus amylophilus to improve lactic acid production using kitchen waste saccharified solution (KWSS). The results demonstrate that L. amylophilus is a homofermentative bacterium. In synthetic medium, 60.6% of the glucose entered the Embden-Meyerhof-Parnas (EMP) to produce lactic acid, whereas 36.4% of the glucose entered the pentose phosphate metabolic pathway (HMP). After solid-liquid separation of the KWSS, the addition of Fe(3+) during fermentation enhanced the NADPH production efficiency and increased the NADH content. The flux to the EMP was also effectively increased. Compared with the control (60.6% flux to EMP without Fe(3+) addition), the flux to the EMP with the addition of Fe(3+) (74.3%) increased by 23.8%. In the subsequent pyruvate metabolism, Fe(3+) also increased lactate dehydrogenase activity, and inhibited alcohol dehydrogenase, pyruvate dehydrogenase and pyruvate carboxylase, thereby increasing the lactic acid production to 9.03 g l(-1) , an increase of 8% compared with the control. All other organic acid by-products were lower than in the control. However, the addition of Zn(2+) showed an opposite effect, decreasing the lactic acid production. In conclusion it is feasible and effective means using GC-MS, isotope experiment and MATLAB software to integrate research the metabolic flux distribution of lactic acid bacteria, and the results provide the theoretical foundation for similar metabolic flux distribution.

  7. Characterization and application of lactic acid bacteria for tropical silage preparation.

    PubMed

    Pholsen, Suradej; Khota, Waroon; Pang, Huili; Higgs, David; Cai, Yimin

    2016-10-01

    Strains TH 14, TH 21 and TH 64 were isolated from tropical silages, namely corn stover, sugar cane top and rice straw, respectively, prepared in Thailand. These strains were selected by low pH growth range and high lactic acid-producing ability, similar to some commercial inoculants. Based on the analysis of 16S ribosomal RNA gene sequence and DNA-DNA relatedness, strain TH 14 was identified as Lactobacillus casei, and strains TH 21 and TH 64 were identified as L. plantarum. Strains TH 14, TH 21, TH 64 and two commercial inoculants, CH (L. plantarum) and SN (L. rhamnosus), were used as additives to fresh and wilted purple Guinea and sorghum silages prepared using a small-scale fermentation method. The number of epiphytic lactic acid bacteria (LAB) in the forages before ensilage was relatively low but the numbers of coliform and aerobic bacteria were higher. Sorghum silages at 30 days of fermentation were all well preserved with low pH (3.56) and high lactic acid production (72.86 g/kg dry matter). Purple Guinea silage inoculated with LAB exhibited reduced count levels of aerobic and coliform bacteria, lower pH, butyric acid and ammonia nitrogen and increased lactic acid concentration, compared with the control. Strain TH 14 more effectively improved lactic acid production compared with inoculants and other strains. © 2016 Japanese Society of Animal Science.

  8. Utilization of by-products derived from bioethanol production process for cost-effective production of lactic acid.

    PubMed

    Moon, Se-Kwon; Wee, Young-Jung; Choi, Gi-Wook

    2014-10-01

    The by-products of bioethanol production such as thin stillage (TS) and condensed distillers solubles (CDS) were used as a potential nitrogen source for economical production of lactic acid. The effect of those by-products and their concentrations on lactic acid fermentation were investigated using Lactobacillus paracasei CHB2121. Approximately, 6.7 g/L of yeast extract at a carbon source to nitrogen source ratio of 15 was required to produce 90 g/L of lactic acid in the medium containing 100 g/L of glucose. Batch fermentation of TS medium resulted in 90 g/L of lactic acid after 48 h, and the medium containing 10 % CDS resulted in 95 g/L of lactic acid after 44 h. Therefore, TS and CDS could be considered as potential alternative fermentation medium for the economical production of lactic acid. Furthermore, lactic acid fermentation was performed using only cassava and CDS for commercial production of lactic acid. The volumetric productivity of lactic acid [2.94 g/(L·h)] was 37 % higher than the productivity obtained from the medium with glucose and CDS.

  9. Simultaneous Saccharification and Fermentation of Sugar Beet Pulp with Mixed Bacterial Cultures for Lactic Acid and Propylene Glycol Production.

    PubMed

    Berlowska, Joanna; Cieciura, Weronika; Borowski, Sebastian; Dudkiewicz, Marta; Binczarski, Michal; Witonska, Izabela; Otlewska, Anna; Kregiel, Dorota

    2016-10-17

    Research into fermentative production of lactic acid from agricultural by-products has recently concentrated on the direct conversion of biomass, whereby pure sugars are replaced with inexpensive feedstock in the process of lactic acid production. In our studies, for the first time, the source of carbon used is sugar beet pulp, generated as a by-product of industrial sugar production. In this paper, we focus on the simultaneous saccharification of lignocellulosic biomass and fermentation of lactic acid, using mixed cultures with complementary assimilation profiles. Lactic acid is one of the primary platform chemicals, and can be used to synthesize a wide variety of useful products, including green propylene glycol. A series of controlled batch fermentations was conducted under various conditions, including pretreatment with enzymatic hydrolysis. Inoculation was performed in two sequential stages, to avoid carbon catabolite repression. Biologically-synthesized lactic acid was catalytically reduced to propylene glycol over 5% Ru/C. The highest lactic acid yield was obtained with mixed cultures. The yield of propylene glycol from the biological lactic acid was similar to that obtained with a water solution of pure lactic acid. Our results show that simultaneous saccharification and fermentation enables generation of lactic acid, suitable for further chemical transformations, from agricultural residues.

  10. Covalent interaction of chloroacetic and acetic acids with cholesterol.

    PubMed

    Bhat, H K; Ansari, G A

    1989-01-01

    The covalent interaction of chloroacetic acid with rat liver lipids was studied in vivo. Rats were given a single oral dose (8.75 mg/kg, 50 microCi) of 1-[14C]chloroacetic acid and sacrificed after 24 hours. Lipids extracted from the livers were separated into neutral lipids and phospholipids by solid-phase extraction using sep-pak silica cartridges. The neutral lipid fraction was further fractionated by preparative thin-layer chromatography followed by reverse-phase high-performance liquid chromatography. The fraction corresponding to the retention time of standard cholesteryl chloroacetate gave a pseudomolecular ion peak at m/z 480/482 ratio: (3:1) on ammonia chemical ionization mass spectrometry, and the fragmentation pattern was found to be similar to that of the standard sample. Under similar conditions, acetic acid resulted in the formation of cholesteryl acetate. The effect of such conjugation reactions on the cell membrane and their contribution to toxicity is presently unknown.

  11. Radioiron utilization and gossypol acetic acid in male rats

    SciTech Connect

    Tone, J.N.; Jensen, D.R.

    1985-01-01

    The 24-h incorporation of VZFe into circulating red blood cells, bone marrow, urine, liver, spleen, and skeletal muscle was measured in splenectomized and sham-splenectomized rats which had received a daily, oral dose of gossypol acetic acid (20 mg GAA/kg body wt) for 91 days. A significant decrease in total body weight gain was observed in all GAA treated animals. Splenectomized rats dosed with GAA exhibited a significant decrease in hemoglobin concentration, hematocrit and erythrocyte count. A significant increase in VZFe incorporation by red blood cells and a decrease in hepatic incorporation of VZFe indicate a preferential utilization of iron in erythropoiesis among GAA treated animals.

  12. FIRST ACETIC ACID SURVEY WITH CARMA IN HOT MOLECULAR CORES

    SciTech Connect

    Shiao, Y.-S. Jerry; Looney, Leslie W.; Snyder, Lewis E.; Friedel, Douglas N.; Remijan, Anthony J. E-mail: aremijan@nrao.ed

    2010-06-10

    Acetic acid (CH{sub 3}COOH) has been detected mainly in hot molecular cores where the distribution between oxygen (O) and nitrogen (N) containing molecular species is cospatial within the telescope beam. Previous work has presumed that similar cores with cospatial O and N species may be an indicator for detecting acetic acid. However, does this presumption hold as higher spatial resolution observations of large O- and N-containing molecules become available? As the number of detected acetic acid sources is still low, more observations are needed to support this postulate. In this paper, we report the first acetic acid survey conducted with the Combined Array for Research in Millimeter-wave Astronomy at 3 mm wavelengths toward G19.61-0.23, G29.96-0.02, and IRAS 16293-2422. We have successfully detected CH{sub 3}COOH via two transitions toward G19.61-0.23 and tentatively confirmed the detection toward IRAS 16293-2422 A. The determined column density of CH{sub 3}COOH is 2.0(1.0) x 10{sup 16} cm{sup -2} and the abundance ratio of CH{sub 3}COOH to methyl formate (HCOOCH{sub 3}) is 2.2(0.1) x 10{sup -1} toward G19.61-0.23. Toward IRAS 16293 A, the determined column density of CH{sub 3}COOH is {approx}1.6 x 10{sup 15} cm{sup -2} and the abundance ratio of CH{sub 3}COOH to methyl formate (HCOOCH{sub 3}) is {approx}1.0 x 10{sup -1}, both of which are consistent with abundance ratios determined toward other hot cores. Finally, we model all known line emission in our passband to determine physical conditions in the regions and introduce a new metric to better reveal weak spectral features that are blended with stronger lines or that may be near the 1{sigma}-2{sigma} detection limit.

  13. The contribution of lactic acid to acidification of tumours: studies of variant cells lacking lactate dehydrogenase.

    PubMed Central

    Yamagata, M.; Hasuda, K.; Stamato, T.; Tannock, I. F.

    1998-01-01

    Solid tumours develop an acidic extracellular environment with high concentration of lactic acid, and lactic acid produced by glycolysis has been assumed to be the major cause of tumour acidity. Experiments using lactate dehydrogenase (LDH)-deficient ras-transfected Chinese hamster ovarian cells have been undertaken to address directly the hypothesis that lactic acid production is responsible for tumour acidification. The variant cells produce negligible quantities of lactic acid and consume minimal amounts of glucose compared with parental cells. Lactate-producing parental cells acidified lightly-buffered medium but variant cells did not. Tumours derived from parental and variant cells implanted into nude mice were found to have mean values of extracellular pH (pHe) of 7.03 +/- 0.03 and 7.03 +/- 0.05, respectively, both of which were significantly lower than that of normal muscle (pHe = 7.43 +/- 0.03; P < 0.001). Lactic acid concentration in variant tumours (450 +/- 90 microg g(-1) wet weight) was much lower than that in parental tumours (1880 +/- 140 microg/g(-1)) and similar to that in serum (400 +/- 35 microg/g(-1)). These data show discordance between mean levels of pHe and lactate content in tumours; the results support those of Newell et al (1993) and suggest that the production of lactic acid via glycolysis causes acidification of culture medium, but is not the only mechanism, and is probably not the major mechanism responsible for the development of an acidic environment within solid tumours. PMID:9667639

  14. Screening, selection and characterization of phytic acid degrading lactic acid bacteria from chicken intestine.

    PubMed

    Raghavendra, Ponnala; Halami, Prakash M

    2009-07-31

    This study was undertaken to screen and select potent phytate degrading lactic acid bacteria and to evaluate their additional characteristic features. Forty lactic acid bacterial strains were isolated from different sources and screened for their ability to degrade myo-inositol hexaphosphate or IP(6) by cobalt chloride staining (plate assay) method, using calcium or sodium salt of phytic acid as substrate. All the forty isolates were able to degrade calcium phytate. However, only two Pediococcus pentosaceus strains (CFR R38 and CFR R35) were found to degrade sodium phytate. These strains showed phytase activity of 213 and 89 U at 50 degrees C, respectively and poor acid phosphatase activity. These strains were further evaluated for additional characteristic features. At pH 2, P. pentosaceus strains CFR R38 and CFR R35 showed 50.7 and 48.5 percentage survivability after 2 h of incubation respectively and they could also withstand 0.3% ox-bile. These cultures exhibited 54.6 and 44.8% of hydrophobicity to xylene, antibacterial activity against food borne pathogens and possessed beta-galactosidase activity. The resistance pattern to several antibiotics was also analyzed. The present study indicates that these strains, having phytate degrading ability and other characteristic features can be exploited as starter cultures in fermented foods to improve the mineral bioavailability.

  15. Physicochemical Properties and Applications of Poly(lactic-co-glycolic acid) for Use in Bone Regeneration

    PubMed Central

    Félix Lanao, Rosa P.; Jonker, Anika M.; Wolke, Joop G.C.; Jansen, John A.; van Hest, Jan C.M.

    2013-01-01

    Poly(lactic-co-glycolic acid) (PLGA) is the most often used synthetic polymer within the field of bone regeneration owing to its biocompatibility and biodegradability. As a consequence, a large number of medical devices comprising PLGA have been approved for clinical use in humans by the American Food and Drug Administration. As compared with the homopolymers of lactic acid poly(lactic acid) and poly(glycolic acid), the co-polymer PLGA is much more versatile with regard to the control over degradation rate. As a material for bone regeneration, the use of PLGA has been extensively studied for application and is included as either scaffolds, coatings, fibers, or micro- and nanospheres to meet various clinical requirements. PMID:23350707

  16. [Effect of pH and fermentation time on yield and optical purity of lactic acid from kitchen wastes fermentation].

    PubMed

    Zhang, Bo; He, Pin-Jing; Shao, Li-Ming

    2007-04-01

    Batch experiments were carried out to analyze the effect of pH and fermentation time on the yield of total lactic acid and the distribution of L- and D-lactic acid among total lactic acid during the non-sterilized fermentation of kitchen wastes. The results show that the concentration of reduced sugar (calculated as organic carbon) is low, and its concentration was higher at neutral and alkali conditions (pH 6 - 8) than at acidic conditions (non-controlled pH and pH = 5). The maximum total lactic acid production rate and yield is 0.59 g x (L x h)(-1) and 0.62 g per gram VS at pH 7, respectively. The proportion of lactic acid (calculated as organic carbon) among the TOC reaches 78% and 89% at controlled pH 7 and 8, respectively. The L-lactic acid is the predominant isomer form at pH 8. Lactic acid concentration depends on pH, fermentation time and interaction from the response surface analysis. pH and fermentation time have a significant effect on the optical purity of lactic acid. At acidic conditions, the ratio of L-lactic acid to the total lactic acid increases with the fermentation time before 120 h, and the ratio reaches 0.9 at 120 h. At alkaline conditions, the ratio keeps at above 0.86 in the whole experimental fermentation time and reachs the maximum value (0.93) at 48 h. It decreases with fermentation time at pH 7. To obtain high lactic acid yield and optical purity simultaneously, it is suggested that pH should be contralled at 8.

  17. Isolation of lactic acid bacteria with potential protective culture characteristics from fruits

    NASA Astrophysics Data System (ADS)

    Hashim, Nurul Huda; Sani, Norrakiah Abdullah

    2015-09-01

    Lactic acid bacteria are also known as beneficial microorganisms abundantly found in fermented food products. In this study, lactic acid bacteria were isolated from fresh cut fruits obtained from local markets. Throughout the isolation process from 11 samples of fruits, 225 presumptive lactic acid bacteria were isolated on MRS agar medium. After catalase and oxidase tests, 149 resulted to fit the characteristics of lactic acid bacteria. Further identification using Gram staining was conducted to identify the Gram positive bacteria. After this confirmation, the fermentation characteristics of these isolates were identified. It was found that 87 (58.4%) isolates were heterofermentative, while the rest of 62 (41.6%) are homofermentative lactic acid bacteria. Later, all these isolates were investigated for the ability to inhibit growth of Staphylococcus aureus using agar spot assay method. Seven (4.7%) isolates showed strong antagonistic capacity, while 127 (85.2%) and 8 (5.4%) isolates have medium and weak antagonistic capacity, respectively. The other 7 (4.7%) isolates indicated to have no antagonistic effect on S. aureus. Results support the potential of LAB isolated in this study which showed strong antagonistic activity against S. aureus may be manipulated to become protective cultures in food products. While the homofermentative or heterofermentative LAB can be utilized in fermentation of food and non-food products depending on the by-products required during the fermentation.

  18. Fermentative production of lactic acid from renewable materials: recent achievements, prospects, and limits.

    PubMed

    Wang, Ying; Tashiro, Yukihiro; Sonomoto, Kenji

    2015-01-01

    The development and implementation of renewable materials for the production of versatile chemical resources have gained considerable attention recently, as this offers an alternative to the environmental problems caused by the petroleum industry and the limited supply of fossil resources. Therefore, the concept of utilizing biomass or wastes from agricultural and industrial residues to produce useful chemical products has been widely accepted. Lactic acid plays an important role due to its versatile application in the food, medical, and cosmetics industries and as a potential raw material for the manufacture of biodegradable plastics. Currently, the fermentative production of optically pure lactic acid has increased because of the prospects of environmental friendliness and cost-effectiveness. In order to produce lactic acid with high yield and optical purity, many studies focus on wild microorganisms and metabolically engineered strains. This article reviews the most recent advances in the biotechnological production of lactic acid mainly by lactic acid bacteria, and discusses the feasibility and potential of various processes.

  19. Antimicrobial activity of ethanol, glycerol monolaurate or lactic acid against Listeria monocytogenes.

    PubMed

    Oh, D H; Marshall, D L

    1993-12-01

    Minimal inhibitory concentrations (MIC) and antimicrobial effects of glycerol monolaurate (monolaurin), ethanol and lactic acid, either alone or in combination, against Listeria monocytogenes in tryptic soy broth were determined. Ethanol at concentrations up to 1.25% did not inhibit growth, but growth was strongly inhibited in the presence of 5% ethanol. MIC values of monolaurin and ethanol alone were 10 micrograms/ml (0.001%) and 50,000 micrograms/ml (5%), respectively. However, MIC values were not changed when monolaurin was combined with ethanol. When 5 micrograms/ml monolaurin was combined with 5% ethanol, the inhibitory effect of the combination was similar to the most active compound alone after 24 h incubation. These data indicate little interaction between monolaurin and ethanol against L. monocytogenes. MIC value of lactic acid alone was 5000 micrograms/ml (0.5%), but was lower when 1.25% ethanol was combined with 0.25% lactic acid. When 2.5% ethanol was combined with 0.25% lactic acid, the combination did not increase the inhibitory effect of the most active single compound alone. This result also indicates that there was little interaction between ethanol and lactic acid.

  20. In vivo blood lactic acid monitoring using microdialysis and surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Hsu, Po-Hsiang; Tsai, Tung-Hu; Chiang, Huihua Kenny

    2008-08-01

    Blood lactic acid concentration is an important indicator for physiological functions. To develop a rapid and sensitive measurement technique for monitoring blood lactic acid may provide a useful tool in clinical diagnosis. We proposed to develop a microdialysis surface-enhanced Raman spectroscopy (microdialysis-SERS) approach to filter/reduce interference from other large metabolites in blood and enhance the detection sensitivity for blood lactic acid. In this study, a microdialysis probe was constructed using 13 kDa cut-off dialysis membrane. The dialysate was mixed with 50 nm Ag colloidal nanoparticles automatically in a micro-fluid chamber for SERS detection under blood microdialysis of Sprague-Dawley rat. The linear range of SERS-lactic acid measurement is 10-5~3x10-4 M with R2 value of 0.99. The optimal mixing flow rate of nanoparticles is 18 μl/min under microdialysis at constant flow rate (2 μl/min). Real time lactic acid monitoring in vivo also has been demonstrated using microdialysis-SERS system.

  1. Efficient production of L-lactic acid from cassava powder by Lactobacillus rhamnosus.

    PubMed

    Wang, Limin; Zhao, Bo; Liu, Bo; Yang, Chunyu; Yu, Bo; Li, Qinggang; Ma, Cuiqing; Xu, Ping; Ma, Yanhe

    2010-10-01

    Cassava is one of the most efficient and rich crops in terms of carbohydrate production, which is a tropical perennial plant that grows on poor or depleted soils. Microbial conversion of such a renewable raw material to useful products is an important objective in industrial biotechnology. L-Lactic acid was efficiently produced from cassava powder by a Lactobacillus rhamnosus strain CASL. The fermentation properties of cassava powder were compared with those of glucose and corn powder. The efficiencies of various fermentation strategies for L-lactic acid production from cassava powder, including simultaneous saccharification and fermentation (SSF), two-step fermentation (TSF) and simultaneous liquefaction, saccharification and fermentation (SLSF), were investigated. The high L-lactic acid concentration (175.4 g/l) was obtained using 275 g/l of cassava powder concentration (total sugar of 222.5 g/l) in SSF batch fermentation. This is the highest L-lactic acid concentration reported, from cassava source, and it provides an efficient L-lactic acid production process with cheap raw bioresources, such as cassava powder.

  2. The importance of lactic acid bacteria for phytate degradation during cereal dough fermentation.

    PubMed

    Reale, Anna; Konietzny, Ursula; Coppola, Raffaele; Sorrentino, Elena; Greiner, Ralf

    2007-04-18

    Lactic acid fermentation of cereal flours resulted in a 100 (rye), 95-100 (wheat), and 39-47% (oat) reduction in phytate content within 24 h. The extent of phytate degradation was shown to be independent from the lactic acid bacteria strain used for fermentation. However, phytate degradation during cereal dough fermentation was positively correlated with endogenous plant phytase activity (rye, 6750 mU g(-1); wheat, 2930 mU g(-1); and oat, 23 mU g(-1)), and heat inactivation of the endogenous cereal phytases prior to lactic acid fermentation resulted in a complete loss of phytate degradation. Phytate degradation was restored after addition of a purified phytase to the liquid dough. Incubation of the cereal flours in buffered solutions resulted in a pH-dependent phytate degradation. The optimum of phytate degradation was shown to be around pH 5.5. Studies on phytase production of 50 lactic acid bacteria strains, previously isolated from sourdoughs, did not result in a significant production of intra- as well as extracellular phytase activity. Therefore, lactic acid bacteria do not participate directly in phytate degradation but provide favorable conditions for the endogenous cereal phytase activity by lowering the pH value.

  3. Viscoelasticity of repaired sciatic nerve by poly(lactic-co-glycolic acid) tubes.

    PubMed

    Piao, Chengdong; Li, Peng; Liu, Guangyao; Yang, Kun

    2013-11-25

    Medical-grade synthetic poly(lactic-co-glycolic acid) polymer can be used as a biomaterial for nerve repair because of its good biocompatibility, biodegradability and adjustable degradation rate. The stress relaxation and creep properties of peripheral nerve can be greatly improved by repair with poly(lactic-co-glycolic acid) tubes. Ten sciatic nerve specimens were harvested from fresh corpses within 24 hours of death, and were prepared into sciatic nerve injury models by creating a 10 mm defect in each specimen. Defects were repaired by anastomosis with nerve autografts and poly(lactic-co-glycolic acid) tubes. Stress relaxation and creep testing showed that at 7 200 seconds, the sciatic nerve anastomosed by poly(lactic-co-glycolic acid) tubes exhibited a greater decrease in stress and increase in strain than those anastomosed by nerve autografts. These findings suggest that poly(lactic-co-glycolic acid) exhibits good viscoelasticity to meet the biomechanical require-ments for a biomaterial used to repair sciatic nerve injury.

  4. Detoxification of Sap from Felled Oil Palm Trunks for the Efficient Production of Lactic Acid.

    PubMed

    Kunasundari, Balakrishnan; Arai, Takamitsu; Sudesh, Kumar; Hashim, Rokiah; Sulaiman, Othman; Stalin, Natra Joseph; Kosugi, Akihiko

    2017-03-30

    The availability of fermentable sugars in high concentrations in the sap of felled oil palm trunks and the thermophilic nature of the recently isolated Bacillus coagulans strain 191 were exploited for lactic acid production under non-sterile conditions. Screening indicated that strain 191 was active toward most sugars including sucrose, which is a major component of sap. Strain 191 catalyzed a moderate conversion of sap sugars to lactic acid (53%) with a productivity of 1.56 g/L/h. Pretreatment of oil palm sap (OPS) using alkaline precipitation improved the sugar fermentability, providing a lactic acid yield of 92% and productivity of 2.64 g/L/h. To better characterize potential inhibitors in the sap, phenolic, organic, and mineral compounds were analyzed using non-treated sap and saps treated with activated charcoal and alkaline precipitation. Phthalic acid, 3,4-dimethoxybenzoic acid, aconitic acid, syringic acid, and ferulic acid were reduced in the sap after treatment. High concentrations of Mg, P, K, and Ca were also precipitated by the alkaline treatment. These results suggest that elimination of excess phenolic and mineral compounds in OPS can improve the fermentation yield. OPS, a non-food resource that is readily available in bulk quantities from plantation sites, is a promising source for lactic acid production.

  5. Use of ionic chromatography in determining the contamination of apple juice by lactic acid.

    PubMed

    Wojtczak, M; Antczak, A; Przybyt, M

    2010-06-01

    High-performance anion exchange chromatography (HPAEC) with conductometric detection was used for the determination of the lactic acid content of apple juice subjected to fermentation with the strains of Lactobacillus brevis and Lactobacillus plantarum, obtained from a collection, at 20 and 30 degrees C. At the same time, lactate content was determined by means of enzymatic tests and biosensors. Lactic acid concentrations determined by the chromatographic method are similar to those obtained during analysis by enzymatic tests. However, acid concentrations determined by means of biosensors substantially diverge from these results.

  6. Quantitative Structure of an Acetate Dye Molecule Analogue at the TiO2-Acetic Acid Interface.

    PubMed

    Hussain, Hadeel; Torrelles, Xavier; Cabailh, Gregory; Rajput, Parasmani; Lindsay, Robert; Bikondoa, Oier; Tillotson, Marcus; Grau-Crespo, Ricardo; Zegenhagen, Jörg; Thornton, Geoff

    2016-04-14

    The positions of atoms in and around acetate molecules at the rutile TiO2(110) interface with 0.1 M acetic acid have been determined with a precision of ±0.05 Å. Acetate is used as a surrogate for the carboxylate groups typically employed to anchor monocarboxylate dye molecules to TiO2 in dye-sensitized solar cells (DSSC). Structural analysis reveals small domains of ordered (2 × 1) acetate molecules, with substrate atoms closer to their bulk terminated positions compared to the clean UHV surface. Acetate is found in a bidentate bridge position, binding through both oxygen atoms to two 5-fold titanium atoms such that the molecular plane is along the [001] azimuth. Density functional theory calculations provide adsorption geometries in excellent agreement with experiment. The availability of these structural data will improve the accuracy of charge transport models for DSSC.

  7. Quantitative Structure of an Acetate Dye Molecule Analogue at the TiO2–Acetic Acid Interface

    PubMed Central

    2016-01-01

    The positions of atoms in and around acetate molecules at the rutile TiO2(110) interface with 0.1 M acetic acid have been determined with a precision of ±0.05 Å. Acetate is used as a surrogate for the carboxylate groups typically employed to anchor monocarboxylate dye molecules to TiO2 in dye-sensitized solar cells (DSSC). Structural analysis reveals small domains of ordered (2 × 1) acetate molecules, with substrate atoms closer to their bulk terminated positions compared to the clean UHV surface. Acetate is found in a bidentate bridge position, binding through both oxygen atoms to two 5-fold titanium atoms such that the molecular plane is along the [001] azimuth. Density functional theory calculations provide adsorption geometries in excellent agreement with experiment. The availability of these structural data will improve the accuracy of charge transport models for DSSC. PMID:27110318

  8. Preservation of acidified cucumbers with a combination of fumaric acid and cinnamaldehyde that target lactic acid bacteria and yeasts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The naturally occurring compound, fumaric acid, was evaluated as a potential preservative for the long-term storage of cucumbers. Fumaric acid inhibited growth of lactic acid bacteria (LAB) in an acidified cucumber juice medium model system resembling conditions that could allow preservation of cucu...

  9. Utilization of Condensed Distillers Solubles as Nutrient Supplement for Production of Nisin and Lactic Acid from Whey

    NASA Astrophysics Data System (ADS)

    Liu, Chuanbin; Hu, Bo; Chen, Shulin; Glass, Richard W.

    The major challenge associated with the rapid growth of the ethanol industry is the usage of the coproducts, i.e., condensed distillers solubles (CDS) and distillers dried grains, which are currently sold as animal feed supplements. As the growth of the livestock industries remains flat, alternative usage of these coproducts is urgently needed. CDS is obtained after the removal of ethanol by distillation from the yeast fermentation of a grain or a grain mixture by condensing the thin stillage fraction to semisolid. In this work, CDS was first characterized and yeast biomass was proven to be the major component of CDS. CDS contained 7.50% crude protein but with only 42% of that protein being water soluble. Then, CDS was applied as a nutrient supplement for simultaneous production of nisin and lactic acid by Lactococcus lactis subsp. lactis (ATCC 11454). Although CDS was able to support bacteria growth and nisin production, a strong inhibition was observed when CDS was overdosed. This may be caused by the existence of the major ethanol fermentation byproducts, especially lactate and acetate, in CDS. In the final step, the CDS based medium composition for nisin and lactic acid production was optimized using response surface methodology.

  10. Utilization of condensed distillers solubles as nutrient supplement for production of nisin and lactic acid from whey.

    PubMed

    Liu, Chuanbin; Hu, Bo; Chen, Shulin; Glass, Richard W

    2007-04-01

    The major challenge associated with the rapid growth of the ethanol industry is the usage of the coproducts, i.e., condensed distillers solubles (CDS) and distillers dried grains, which are currently sold as animal feed supplements. As the growth of the livestock industries remains flat, alternative usage of these coproducts is urgently needed. CDS is obtained after the removal of ethanol by distillation from the yeast fermentation of a grain or a grain mixture by condensing the thin stillage fraction to semisolid. In this work, CDS was first characterized and yeast biomass was proven to be the major component of CDS. CDS contained 7.50% crude protein but with only 42% of that protein being water soluble. Then, CDS was applied as a nutrient supplement for simultaneous production of nisin and lactic acid by Lactococcus lactis subsp. lactis (ATCC 11454). Although CDS was able to support bacteria growth and nisin production, a strong inhibition was observed when CDS was overdosed. This may be caused by the existence of the major ethanol fermentation byproducts, especially lactate and acetate, in CDS. In the final step, the CDS based medium composition for nisin and lactic acid production was optimized using response surface methodology.

  11. Improvement of acetic acid tolerance of Saccharomyces cerevisiae using a zinc-finger-based artificial transcription factor and identification of novel genes involved in acetic acid tolerance.

    PubMed

    Ma, Cui; Wei, Xiaowen; Sun, Cuihuan; Zhang, Fei; Xu, Jianren; Zhao, Xinqing; Bai, Fengwu

    2015-03-01

    Acetic acid is present in cellulosic hydrolysate as a potent inhibitor, and the superior acetic acid tolerance of Saccharomyces cerevisiae ensures good cell viability and efficient ethanol production when cellulosic raw materials are used as substrates. In this study, a mutant strain of S. cerevisiae ATCC4126 (Sc4126-M01) with improved acetic acid tolerance was obtained through screening strains transformed with an artificial zinc finger protein transcription factor (ZFP-TF) library. Further analysis indicated that improved acetic acid tolerance was associated with improved catalase (CAT) activity. The ZFP coding sequence associated with the improved phenotype was identified, and real-time RT-PCR analysis revealed that three of the possible genes involved in the enhanced acetic acid tolerance regulated by this ZFP-TF, namely YFL040W, QDR3, and IKS1, showed decreased transcription levels in Sc4126-M01 in the presence of acetic acid, compared to those in the control strain. Sc4126-M01 mutants having QDR3 and IKS1 deletion (ΔQDR3 and ΔIKS1) exhibited higher acetic acid tolerance than the wild-type strain under acetic acid treatment. Glucose consumption rate and ethanol productivity in the presence of 5 g/L acetic acid were improved in the ΔQDR3 mutant compared to the wild-type strain. Our studies demonstrated that the synthetic ZFP-TF library can be used to improve acetic acid tolerance of S. cerevisiae and that the employment of an artificial transcription factor can facilitate the exploration of novel functional genes involved in stress tolerance of S. cerevisiae.

  12. [Effect of acetic acid on adsorption of acid phosphatase by some soil colloids and clay minerals].

    PubMed

    Zhao, Zhenhua; Huang, Qiaoyun; Jiang, Xin; Yu, Guifen; Wang, Fang; Li, Xueyuan

    2004-03-01

    This paper studied the effect of acetic acid with different concentrations and pH values on the adsorption of acid phosphatase by some soil colloids and clay minerals (SCCM). The results showed that the pH values for the maximum adsorption of the enzyme were between the IEP of the enzyme and the PZC of SCCM. In the acetic acid systems, the amount of the enzyme adsorbed by SCCM was in the order of goethite > yellow brown soil > latosol > kaolinite > delta-MnO2. A remarkable influence of acetic acid concentration on the adsorption amount and the binding energy of the enzyme was observed. With the increase of the concentration from 0 to 200 mmol.L-1 in the system, acetic acid exhibited an enhanced effect, followed by an inhibition action on the adsorption of the enzyme on SCCM. The changes of the binding energy (K value) for the enzyme on SCCM were on the contrary to those of the maximum adsorption. The possible mechanisms for the influence of acetic acid on the adsorption of enzyme by SCCM were also discussed.

  13. Stereocomplexation of low molecular weight poly(L-lactic acid) and high molecular weight poly(D-lactic acid), radiation crosslinking PLLA/PDLA stereocomplexes and their characterization

    NASA Astrophysics Data System (ADS)

    Quynh, Tran Minh; Mai, Hoang Hoa; Lan, Pham Ngoc

    2013-02-01

    Poly(L-lactic acid)s (PLLAx) were synthesized from L-lactic acid by polycondensation. Different stereocomplexes were also obtained with equimolar mixtures of synthesized PLLAx and a commercial PDLA. The stereocomplexes were crosslinked with triallyl isocyanurate (TAIC) by gamma irradiation. Crosslinking density increased with radiation doses, the heavier the crosslinking network, the lower its swelling degree. The crosslinking structures were introduced in the stereocomplexes inhibiting the mobility for crystallization of PLLA molecules. Thermal and mechanical properties of PLA stereocomplexes were remarkably enhanced by radiation induced crosslinking. PLA stereocomplex does not seem to be degraded by PLLA degrading microorganisms existing in compost at room temperature, but the synthesized PLLA was significantly degraded.

  14. Rapid identification, by use of the LTQ Orbitrap hybrid FT mass spectrometer, of antifungal compounds produced by lactic acid bacteria.

    PubMed

    Brosnan, Brid; Coffey, Aidan; Arendt, Elke K; Furey, Ambrose

    2012-07-01

    Fungal contamination of food causes health and economic concerns. Several species of lactic acid bacteria (LAB) have antifungal activity which may inhibit food spoilage fungi. LAB have GRAS (generally recognised as safe) status, allowing them to be safely integrated into food systems as natural food preservatives. A method is described herein that enables rapid screening of LAB cultures for 25 known antifungal compounds associated with LAB. This is the first chromatographic method developed which enables the rapid identification of a wide range of antifungal compounds by a single method with a short analysis time (23 min). Chromatographic separation was achieved on a Phenomenex Gemini C18 100A column (150 mm × 2.0 mm; 5 μm) by use of a mobile-phase gradient prepared from (A) water containing acetic acid (0.1%) and (B) acetonitrile containing acetic acid (0.1%), at a flow rate of 0.3 µL min(-1). The gradient involved a progressive ramp from 10-95% acetonitrile over 13 min. The LC was coupled to a hybrid LTQ Orbitrap XL fourier-transform mass spectrometer (FTMS) operated in negative ionisation mode. High mass accuracy data (<3 ppm) obtained by use of high resolution (30,000 K) enabled unequivocal identification of the target compounds. This method allows comprehensive profiling and comparison of different LAB strains and is also capable of the identification of additional compounds produced by these bacteria.

  15. Development of Conducting Polyaniline/ Poly(Lactic Acid) Nanofibers by Electrospinning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultrafine fibers consisting of blends of polyaniline doped with p-toluene sulfonic acid and poly(L-lactic acid) were prepared by electrospinning. The presence of polyaniline resulted in fibers with diameters as thin as 100– 200 nm and a significant reduction of bead formation. These fibers were visu...

  16. Separation of the rare earths by anion-exchange in the presence of lactic acid

    NASA Technical Reports Server (NTRS)

    Faris, J. P.

    1969-01-01

    Investigation of adsorption of rare earths and a few other elements to an anion-exchange resin from mixed solvents containing lactic acid shows that the lanthanides are absorbed more strongly than from the alpha-hydroxyisobutryric acid system, but with less separation between adjacent members of the series.

  17. Report membrane transport of lactic acid in the filamentous fungus Rhizopus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Rhizopus is frequently used for fermentative production of lactic acid, but little is known about the mechanisms or proteins for transporting this carboxylic acid. Since transport of the lactate anion across the plasma membrane is critical to prevent acidification of the cytoplasm, we ev...

  18. Unusal pattern of product inhibition: batch acetic acid fermentation

    SciTech Connect

    Bar, R.; Gainer, J.L.; Kirwan, D.J.

    1987-04-20

    The limited tolerance of microorganisms to their metabolic products results in inhibited growth and product formation. The relationship between the specific growth rate, micro, and the concentration of an inhibitory product has been described by a number of mathematical models. In most cases, micro was found to be inversely proportional to the product concentration and invariably the rate of substrate utilization followed the same pattern. In this communication, the authors report a rather unusual case in which the formation rate of a product, acetic acid, increased with a decreasing growth rate of the microorganism, Acetobacter aceti. Apparently, a similar behavior was mentioned in a review report with respect to Clostridium thermocellum in a batch culture but was not published in the freely circulating literature. The fermentation of ethanol to acetic acid, C/sub 2/H/sub 5/OH + O/sub 2/ = CH/sub 3/COOH + H/sub 2/O is clearly one of the oldest known fermentations. Because of its association with the commercial production of vinegar it has been a subject of extensive but rather technically oriented studies. Suprisingly, the uncommon uncoupling between the inhibited microbial growth and the product formation appears to have been unnoticed. 13 references.

  19. Occurrence and role of lactic acid bacteria in seafood products.

    PubMed

    Françoise, Leroi

    2010-09-01

    Lactic acid bacteria (LAB) in fish flesh has long been disregarded because the high post-mortem pH, the low percentage of sugars, the high content of low molecular weight nitrogenous molecules and the low temperature of temperate waters favor the rapid growth of pH-sensitive psychrotolerant marine Gram-negative bacteria like Pseudomonas, Shewanella and Photobacterium. In seafood packed in both vacuum (VP) and modified atmosphere (MAP) packaging commonly CO(2) enriched, the growth of the Gram-negative aerobic bacteria group (predominantly pseudomonads) is effectively inhibited and the number reached by LAB during storage is higher than that achieved in air but always several log units lower than the trimethylamine oxide (TMA-O) reducing and CO(2)-resistant organisms (Shewanella putrefaciens and Photobacterium phosphoreum). Accordingly, LAB are not of much concern in seafood neither aerobically stored nor VP and MAP. However, they may acquire great relevance in lightly preserved fish products (LPFP), including those VP or MAP. Fresh fish presents a very high water activity (aw) value (0.99). However, aw is reduced to about 0.96 when salt (typically 6% WP) is added to the product. As a result, aerobic Gram-negative bacteria are inhibited, which allows the growth of other organisms more resistant to reduced aw, i.e. LAB, and then they may acquire a central role in the microbial events occurring in the product. Changes in consumers' habits have led to an increase of convenient LPFP with a relative long shelf-life (at least 3 weeks) which, on the other hand, may constitute a serious problem from a safety perspective since Listeria monocytogenes and sometimes Clostridium botulinum (mainly type E) may able to grow. In any case the LAB function in marine products is complex, depending on species, strains, interaction with other bacteria and the food matrix. They may have no particular effect or they may be responsible for spoilage and, in certain cases, they may even exert

  20. More value from food waste: Lactic acid and biogas recovery.

    PubMed

    Kim, Mi-Sun; Na, Jeong-Geol; Lee, Mo-Kwon; Ryu, Hoyoung; Chang, Yong-Keun; Triolo, Jin M; Yun, Yeo-Myeong; Kim, Dong-Hoon

    2016-06-01

    Anaerobic digestion (AD) is one of the traditional technologies for treating organic solid wastes, but its economic benefit is sometimes questioned. To increase the economic feasibility of the treatment process, the aim of this study was to recover not only biogas from food waste but lactic acid (LA) as well. At first, LA fermentation of food waste (FW) was conducted using an indigenous mixed culture. During the operation, temperature was gradually increased from 35 °C to 55 °C, with the highest performance attained at 50 °C. At 50 °C and hydraulic retention time (HRT) of 1.0 d, LA concentration in the broth was 40 kg LA/m(3), corresponding to a yield of 1.6 mol LA/mol hexoseadded. Pyrosequencing results showed that Lactobacillus (97.6% of the total number of sequences) was the predominant species performing LA fermentation of FW. The fermented broth was then centrifuged and LA was extracted from the supernatant by the combined process of nanofiltration and water-splitting electrodialysis. The process could recover highly purified LA by removing 85% of mineral ions such as Na(+), K(+), Mg(2+), and Ca(2+) and 90% of residual carbohydrates. Meanwhile, the solid residue remained after centrifugation was further fermented to biogas by AD. At HRT 40 d (organic loading rate of 7 kg COD/m(3)/d), the highest volumetric biogas production rate of 3.5 m(3)/m(3)/d was achieved with a CH4 yield of 0.25 m(3) CH4/kg COD. The mass flow showed that 47 kg of LA and 54 m(3) of biogas could be recovered by the developed process from 1 ton of FW with COD removal efficiency of 70%. These products have a higher economic value 60 USD/ton FW compared to that of conventional AD (27 USD/ton FW).

  1. Optimization of a biomimetic poly-(lactic acid) ligament scaffold

    NASA Astrophysics Data System (ADS)

    Uehlin, Andrew F.

    The anterior cruciate ligament (ACL) is the most commonly injured ligament of the knee, often requiring orthopedic reconstruction using autograft or allograph tissue, both with significant disadvantages. As a result, tissue engineering an ACL replacement graft has been heavily investigated. The present study attempts to replicate the morphology and mechanical properties of the ACL using a nanomatrix composite of highly-aligned poly(lactic acid) (PLA) fibers with various surface and biochemical modifications. Additionally, this study attempts to recreate the natural mineralization gradient found at the ACL enthesis onto the scaffold, capable of inducing a favorable cellular response in vitro. Unidirectional electrospinning was used to create nanofibers of PLA, followed by an induced degradation of the nanofibers via 0.25M NaOH hydrolysis. The effects of the unidirectional electrospinning as well as the effects of NaOH hydrolysis on fiber alignment, fiber diameter, surface morphology, crystallinity, in vitro swelling, immobilization of fibrin, and mechanical properties were investigated, resulting in a modified morphology correlating to the microstructure of native ligament tissue with similar mechanical properties. Furthering the development of the PLA nanomatrix composite, a bioinkjet printer was used to immobilize nanoparticulate hydroxyapatite (HANP) on the surface of the scaffold. A series of 300pL droplets of HANP bioink were printed over a gradient pattern mimetic of (and spatially corresponding to) the mineralization gradient found over the microanatomy at the ACL enthesis. Proliferation and differentiation response of human mesenchymal stem cells (hMSCs) in vitro was assessed on a variety of conditions and combinations of the PLA nanofiber scaffold surface modifications (inclusive and exclusive of HANP, fibrin, and various time dependent NaOH treatments). It was found that a combinatory effect of the HANP gradient with fibrin on 20 minute NaOH treated PLA

  2. Superabsorbent biphasic system based on poly(lactic acid) and poly(acrylic acid)

    NASA Astrophysics Data System (ADS)

    Sartore, Luciana; Pandini, Stefano; Baldi, Francesco; Bignotti, Fabio

    2016-05-01

    In this research work, biocomposites based on crosslinked particles of poly(acrylic acid), commonly used as superabsorbent polymer (SAP), and poly-L-lactic acid (PLLA) were developed to elucidate the role of the filler (i.e., polymeric crosslinked particles) on the overall physico-mechanical behavior and to obtain superabsorbent thermoplastic products. Samples prepared by melt-blending of components in different ratios showed a biphasic system with a regular distribution of particles, with diameter ranging from 5 to 10 μm, within the PLLA polymeric matrix. The polymeric biphasic system, coded PLASA i.e. superabsorbent poly(lactic acid), showed excellent swelling properties, demonstrating that cross-linked particles retain their superabsorbent ability, as in their free counterparts, even if distributed in a thermoplastic polymeric matrix. The thermal characteristics of the biocomposites evidence enhanced thermal stability in comparison with neat PLLA and also mechanical properties are markedly modified by addition of crosslinked particles which induce regular stiffening effect. Furthermore, in aqueous environments the particles swell and are leached from PLLA matrix generating very high porosity. These new open-pore PLLA foams, produced in absence of organic solvents and chemical foaming agents, with good physico-mechanical properties appear very promising for several applications, for instance in tissue engineering for scaffold production.

  3. Metabolite changes during natural and lactic acid bacteria fermentations in pastes of soybeans and soybean–maize blends

    PubMed Central

    Ng'ong'ola-Manani, Tinna Austen; Østlie, Hilde Marit; Mwangwela, Agnes Mbachi; Wicklund, Trude

    2014-01-01

    The effect of natural and lactic acid bacteria (LAB) fermentation processes on metabolite changes in pastes of soybeans and soybean–maize blends was studied. Pastes composed of 100% soybeans, 90% soybeans and 10% maize, and 75% soybeans and 25% maize were naturally fermented (NFP), and were fermented by lactic acid bacteria (LFP). LAB fermentation processes were facilitated through back-slopping using a traditional fermented gruel, thobwa as an inoculum. Naturally fermented pastes were designated 100S, 90S, and 75S, while LFP were designated 100SBS, 90SBS, and 75SBS. All samples, except 75SBS, showed highest increase in soluble protein content at 48 h and this was highest in 100S (49%) followed by 90SBS (15%), while increases in 100SBS, 90S, and 75S were about 12%. Significant (P < 0.05) increases in total amino acids throughout fermentation were attributed to cysteine in 100S and 90S; and methionine in 100S and 90SBS. A 3.2% increase in sum of total amino acids was observed in 75SBS at 72 h, while decreases up to 7.4% in 100SBS at 48 and 72 h, 6.8% in 100S at 48 h and 4.7% in 75S at 72 h were observed. Increases in free amino acids throughout fermentation were observed in glutamate (NFP and 75SBS), GABA and alanine (LFP). Lactic acid was 2.5- to 3.5-fold higher in LFP than in NFP, and other organic acids detected were acetate and succinate. Maltose levels were the highest among the reducing sugars and were two to four times higher in LFP than in NFP at the beginning of the fermentation, but at 72 h, only fructose levels were significantly (P < 0.05) higher in LFP than in NFP. Enzyme activities were higher in LFP at 0 h, but at 72 h, the enzyme activities were higher in NFP. Both fermentation processes improved nutritional quality through increased protein and amino acid solubility and degradation of phytic acid (85% in NFP and 49% in LFP by 72 h). PMID:25493196

  4. Lactic acid production by Rhizopus oryzae transformants with modified lactate dehydrogenase activity.

    PubMed

    Skory, C D

    2004-04-01

    Rhizopus oryzae is capable of producing high levels of lactic acid by the fermentation of glucose. Yields typically vary over 60-80%, with the remaining glucose diverted primarily into ethanol fermentation. The goal of this work was to increase lactate dehydrogenase (LDH) activity, so lactic acid fermentation could more effectively compete for available pyruvate. Three different constructs, pLdhA71X, pLdhA48XI, and pLdhA89VII, containing various lengths of the ldhA gene fragment, were transformed into R. oryzae. This fungus rarely integrates DNA used for transformation, but instead relies on extra-chromosomal replication in a high-copy number. Plasmid pLdhA48XI was linearized prior to transformation in order to facilitate integration into the pyrG gene used for selection. Isolates transformed with ldhA containing plasmid were compared with both the wild-type parent strain and the auxotrophic recipient strain containing vector only. All isolates transformed with pLdhA71X or pLdhA48XI had multiple copies of the ldhA gene that resulted in ldhA transcript accumulation, LDH specific activity, and lactic acid production higher than the controls. Integration of plasmid pLdhA48XI increased the stability of the strain, but did not seem to offer any benefit for increasing lactic acid production. Since lactic acid fermentation competes with ethanol and fumaric acid production, it was not unexpected that increased lactic acid production was always concomitant with decreased ethanol and fumaric acid. Plasmid pLdhA71X, containing a large ldhA fragment (6.1 kb), routinely yielded higher levels of lactic acid than the smaller region (3.3 kb) used to construct plasmid pLdhA48XI. The greatest levels of ldhA transcript and enzyme production occurred with isolates transformed with plasmid pLdhA89VII. However, these transformants always produced less lactic acid and higher amounts of ethanol, fumaric, and glycerol compared with the control.

  5. Capacity of lactic acid bacteria in immunity enhancement and cancer prevention.

    PubMed

    Riaz Rajoka, Muhammad Shahid; Shi, Junling; Zhu, Jing; Shao, Dongyan; Huang, Qingsheng; Yang, Hui; Jin, Mingliang

    2017-01-01

    Lactic acid bacteria are associated with the human gastrointestinal tract. They are important for maintaining the balance of microflora in the human gut. An increasing number of published research reports in recent years have denoted the importance of producing interferon-gamma and IgA for treatment of disease. These agents can enhance the specific and nonspecific immune systems that are dependent on specific bacterial strains. The mechanisms of these effects were revealed in this investigation, where the cell walls of these bacteria were modulated by the cytokine pathways, while the whole bacterial cell mediated the host cell immune system and regulated the production of tumor necrosis factors and interleukins. A supplement of highly active lactic acid bacteria strains provided significant potential to enhance host's immunity, offering prevention from many diseases including some cancers. This review summarizes the current understanding of the function of lactic acid bacteria immunity enhancement and cancer prevention.

  6. Complete Genome Sequence of a thermotolerant sporogenic lactic acid bacterium, Bacillus coagulans strain 36D1

    PubMed Central

    Rhee, Mun Su; Moritz, Brélan E.; Xie, Gary; Glavina del Rio, T.; Dalin, E.; Tice, H.; Bruce, D.; Goodwin, L.; Chertkov, O.; Brettin, T.; Han, C.; Detter, C.; Pitluck, S.; Land, Miriam L.; Patel, Milind; Ou, Mark; Harbrucker, Roberta; Ingram, Lonnie O.; Shanmugam, K. T.

    2011-01-01

    Bacillus coagulans is a ubiquitous soil bacterium that grows at 50-55 °C and pH 5.0 and ferments various sugars that constitute plant biomass to L (+)-lactic acid. The ability of this sporogenic lactic acid bacterium to grow at 50-55 °C and pH 5.0 makes this organism an attractive microbial biocatalyst for production of optically pure lactic acid at industrial scale not only from glucose derived from cellulose but also from xylose, a major constituent of hemicellulose. This bacterium is also considered as a potential probiotic. Complete genome sequence of a representative strain, B. coagulans strain 36D1, is presented and discussed. PMID:22675583

  7. Complete Genome Sequence of a thermotolerant sporogenic lactic acid bacterium, Bacillus coagulans strain 36D1

    SciTech Connect

    Xie, Gary; Dalin, Eileen; Tice, Hope; Chertkov, Olga; Land, Miriam L

    2011-01-01

    Bacillus coagulans is a ubiquitous soil bacterium that grows at 50-55 C and pH 5.0 and fer-ments various sugars that constitute plant biomass to L (+)-lactic acid. The ability of this sporogenic lactic acid bacterium to grow at 50-55 C and pH 5.0 makes this organism an attractive microbial biocatalyst for production of optically pure lactic acid at industrial scale not only from glucose derived from cellulose but also from xylose, a major constituent of hemi-cellulose. This bacterium is also considered as a potential probiotic. Complete genome squence of a representative strain, B. coagulans strain 36D1, is presented and discussed.

  8. Complete Genome Sequence of a thermotolerant sporogenic lactic acid bacterium, Bacillus coagulans strain 36D1

    SciTech Connect

    Rhee, Mun Su; Moritz, Brelan E.; Xie, Gary; Glavina Del Rio, Tijana; Dalin, Eileen; Tice, Hope; Bruce, David; Goodwin, Lynne A.; Chertkov, Olga; Brettin, Thomas S; Han, Cliff; Detter, J. Chris; Pitluck, Sam; Land, Miriam L; Patel, Milind; Ou, Mark; Harbrucker, Roberta; Ingram, Lonnie O.; Shanmugam, Keelnathan T.

    2011-01-01

    Bacillus coagulans is a ubiquitous soil bacterium that grows at 50-55 C and pH 5.0 and fer- ments various sugars that constitute plant biomass to L (+)-lactic acid. The ability of this spo- rogenic lactic acid bacterium to grow at 50-55 C and pH 5.0 makes this organism an attrac- tive microbial biocatalyst for production of optically pure lactic acid at industrial scale not only from glucose derived from cellulose but also from xylose, a major constituent of hemi- cellulose. This bacterium is also considered as a potential probiotic. Complete genome se- quence of a representative strain, B. coagulans strain 36D1, is presented and discussed.

  9. Complete Genome Sequence of a thermotolerant sporogenic lactic acid bacterium, Bacillus coagulans strain 36D1.

    PubMed

    Rhee, Mun Su; Moritz, Brélan E; Xie, Gary; Glavina Del Rio, T; Dalin, E; Tice, H; Bruce, D; Goodwin, L; Chertkov, O; Brettin, T; Han, C; Detter, C; Pitluck, S; Land, Miriam L; Patel, Milind; Ou, Mark; Harbrucker, Roberta; Ingram, Lonnie O; Shanmugam, K T

    2011-12-31

    Bacillus coagulans is a ubiquitous soil bacterium that grows at 50-55 °C and pH 5.0 and ferments various sugars that constitute plant biomass to L (+)-lactic acid. The ability of this sporogenic lactic acid bacterium to grow at 50-55 °C and pH 5.0 makes this organism an attractive microbial biocatalyst for production of optically pure lactic acid at industrial scale not only from glucose derived from cellulose but also from xylose, a major constituent of hemicellulose. This bacterium is also considered as a potential probiotic. Complete genome sequence of a representative strain, B. coagulans strain 36D1, is presented and discussed.

  10. Modification of cellulose nanocrystals with lactic acid for direct melt blending with PLA

    NASA Astrophysics Data System (ADS)

    Spinella, Stephen; Re, Giada Lo; Liu, Bo; Dorgan, John; Habibi, Youssef; Raquez, Jean-Marie; Dubois, Philippe; Gross, Richard A.

    2015-05-01

    Polylactide (PLA) is a commercially produced bio-based thermoplastic with unique properties such as high strength, biocompatibility and biodegradability. However, the low heat deflection temperature (HDT) of PLA significantly impedes its industrial implementation for high-performance applications, requiring the design of PLA-based nanocomposites. Cellulose nanocrystals (CNCs) are derived from cellulose which is highly abundant in nature, non-toxic, biodegradable, and has a low density. CNCs possess many attractive features for use in nano-composites. The main problem of adding hydrophilic CNCs into hydrophobic matrixes is their lack of affinity, leading to phase separation and a decrease in mechanical properties. A one-step method based on both Fischer esterification and acid hydrolysis was used in this work to obtain functionalized and ready-to-use CNCs, with the aim to improve the filler dispersion into the polymeric matrix. The study assesses the reinforcing effect of CNCs on PLA-based materials. CNCs functionalized with acetate (AA-CNCs), lactic acid (LA-CNCs) and unfunctionalized CNCs were synthesized and blends of PLA and these CNCs were prepared by direct melt blending. The corresponding thermomechanical properties were investigated by DMTA. Blends with LA-CNCs possessed the highest storage modulus. Based on these results, blends with up to 20 % LA-CNCs were prepared by direct melt blending and an increase of up to 20°C in the HDT resulted. A decrease in oxygen permeability also resulted from increasing the nano-filler content. This increase in materials properties can potentially expand the applications of PLA based materials.

  11. Production of γ-Amino Butyric Acid in Tea Leaves wit Treatment of Lactic Acid Bacteria

    NASA Astrophysics Data System (ADS)

    Watanabe, Yuko; Hayakawa, Kiyoshi; Ueno, Hiroshi

    Lactic acid bacteria was searched for producing termented tea that contained a lot of γ-amino butyric acid(GABA). Also examined were the growth condition, GABA production and changes in catechin contents in the tea leaves. Lactobacillus brevis L12 was found to be suitable for the production of fermented tea since it gave as much GABA as gabaron tea when tea leaves being suspended with water at 10% and incubated for 4 days at 25°C. The amount of GABA produced was more than calculated based upon the content of glutamic acid in tea leaves. It is probable to assume that glutamate derived from glutamine and theanine is converted into GABA.

  12. Heterogeneous Reactions of Acetic Acid with Oxide Surfaces: Effects of Mineralogy and Relative Humidity.

    PubMed

    Tang, Mingjin; Larish, Whitney A; Fang, Yuan; Gankanda, Aruni; Grassian, Vicki H

    2016-07-21

    We have investigated the heterogeneous uptake of gaseous acetic acid on different oxides including γ-Al2O3, SiO2, and CaO under a range of relative humidity conditions. Under dry conditions, the uptake of acetic acid leads to the formation of both acetate and molecularly adsorbed acetic acid on γ-Al2O3 and CaO and only molecularly adsorbed acetic acid on SiO2. More importantly, under the conditions of this study, dimers are the major form for molecularly adsorbed acetic acid on all three particle surfaces investigated, even at low acetic acid pressures under which monomers are the dominant species in the gas phase. We have also determined saturation surface coverages for acetic acid adsorption on these three oxides under dry conditions as well as Langmuir adsorption constants in some cases. Kinetic analysis shows that the reaction rate of acetic acid increases by a factor of 3-5 for γ-Al2O3 when relative humidity increases from 0% to 15%, whereas for SiO2 particles, acetic acid and water are found to compete for surface adsorption sites.

  13. Relative catalytic efficiency of ldhL- and ldhD-encoded products is crucial for optical purity of lactic acid produced by lactobacillus strains.

    PubMed

    Zheng, Zhaojuan; Sheng, Binbin; Ma, Cuiqing; Zhang, Haiwei; Gao, Chao; Su, Fei; Xu, Ping

    2012-05-01

    NAD-dependent l- and d-lactate dehydrogenases coexist in Lactobacillus genomes and may convert pyruvic acid into l-lactic acid and d-lactic acid, respectively. Our findings suggest that the relative catalytic efficiencies of ldhL- and ldhD-encoded products are crucial for the optical purity of lactic acid produced by Lactobacillus strains.

  14. Enhancement and modeling of microparticle-added Rhizopus oryzae lactic acid production.

    PubMed

    Coban, Hasan Bugra; Demirci, Ali

    2016-02-01

    Lactic acid has a wide industrial application area and can be produced by fungal strains. However, excessive bulk growth form of fungi during the fermentations is a major problem, which limits the fermentation performance. Microparticles are excellent tools to prevent bulk fungal growth and provide homogenized fermentation broth to increase uniformity and the prediction performance of the models. Therefore, in this study, addition of aluminum oxide and talcum microparticles into fermentations was evaluated to enhance the production of lactic acid by Rhizopus oryzae. The results showed that the bulk fungal growth was prevented and the lactic acid concentration increased from 6.02 to 13.88 and 24.01 g/L, when 15 g/L of aluminum oxide or 10 g/L of talcum was used, respectively, in the shake-flask fermentations. Additionally, substrate concentration, pH, and agitation were optimized in the bioreactors using response surface methodology, and optimum values were determined as 126 g/L of glucose, 6.22 pH, and 387 rpm, respectively. Under these conditions, lactic acid production further increased to 75.1 ± 1.5 g/L with 10 g/L of talcum addition. Also, lactic acid production and glucose consumption in the batch fermentation were successfully modeled with modified Gompertz model and modified logistic model. RMSE and MAE values for lactic acid production were calculated as 2.279 and 1.498 for the modified Gompertz model; 3.6 and 4.056 for the modified logistic model. Additionally, modified logistic model predicted glucose consumption with -2.088 MAE and 2.868 RMSE, whereas these values were calculated as 2.035 and 3.946 for the modified Gompertz model.

  15. Water-lactose behavior as a function of concentration and presence of lactic acid in lactose model systems.

    PubMed

    Wijayasinghe, Rangani; Vasiljevic, Todor; Chandrapala, Jayani

    2015-12-01

    The presence of high amounts of lactic acid in acid whey restricts its ability to be further processed because lactose appears to remain in its amorphous form. A systematic study is lacking in this regard especially during the concentration step. Hence, the main aim of the study was to establish the structure and behavior of water molecules surrounding lactose in the presence of 1% (wt/wt) lactic acid at a concentration up to 50% (wt/wt). Furthermore, the crystallization nature of freeze-dried lactose with or without lactic acid was established using differential scanning calorimetry and Fourier transform infrared spectroscopy. Two mechanisms were proposed to describe the behavior of water molecules around lactose molecules during the concentration of pure lactose and lactose solutions with lactic acid. Pure lactose solution exhibited a water evaporation enthalpy of ~679 J·g(-1), whereas lactose+ lactic acid solution resulted in ~965 J·g(-1) at a 50% (wt/wt) concentration. This indicates a greater energy requirement for water removal around lactose in the presence of lactic acid. Higher crystallization temperatures were observed with the presence of lactic acid, indicating a delay in crystallization. Furthermore, less crystalline lactose (~12%) was obtained in the presence of lactic acid, indicating high amorphous nature compared with pure lactose where ~50% crystallinity was obtained. The Fourier transform infrared spectra revealed that the strong hydration layer consisting lactic acid and H3O(+) ions surrounded lactose molecules via strong H bonds, which restricted water mobility, induced a change in structure of lactose, or both, creating unfavorable conditions for lactose crystallization. Thus, partial or complete removal of lactic acid from acid whey may be the first step toward improving the ability of acid whey to be processed.

  16. Concentration Dependent Influence of Lipopolysaccharides on Separation of Hoof Explants and Supernatant Lactic Acid Concentration in an Ex Vivo/In Vitro Laminitis Model.

    PubMed

    Reisinger, Nicole; Schaumberger, Simone; Nagl, Veronika; Hessenberger, Sabine; Schatzmayr, Gerd

    2015-01-01

    Laminitis is one of the most common diseases in horses. It is not only painful for the animal, but also has a significant financial impact on the equine industry. This multifactorial disease affects the connective tissue of the hoof. However, the pathogenesis of laminitis is still not fully understood. Endotoxins, also known as lipopolysaccharides (LPS), and bacterial exotoxins seem to play an important role during the development of laminitis. The aim of our study was to investigate the effect of increasing LPS concentrations (0, 2.5, 5, 10, and 100 μg/mL) on cell viability of isolated epidermal and dermal hoof cells as well as on the tissue integrity of hoof explants. Furthermore, glucose, acetic acid, lactic acid, and propionic acid concentrations in explant supernatants were measured to evaluate the energy metabolism in the hoof tissue. LPS did not exhibit cytotoxic effects on epidermal or dermal cells. Force required to separate LPS treated hoof explants decreased in a concentration dependent manner. Specifically, explants incubated with 10 and 100 μg/mL needed significantly less force to separate compared to control explants. Lactic acid concentrations were significantly decreased in explants incubated with 5, 10, or 100 μg/mL LPS, while glucose, acetic acid and propionic acid concentrations were unaffected by LPS treatment. Our study indicates that LPS has no cytotoxic effect on epidermal and dermal cells isolated from hoof tissue, but impairs integrity of hoof explants. In addition, LPS led to an alteration of the lactic acid production in the lamellar tissue. Since our data highlight that LPS can affect the integrity of the equine hoof tissue in vitro, endotoxins should be further explored for their contribution to facilitate the development of laminitis.

  17. Concentration Dependent Influence of Lipopolysaccharides on Separation of Hoof Explants and Supernatant Lactic Acid Concentration in an Ex Vivo/In Vitro Laminitis Model

    PubMed Central

    Reisinger, Nicole; Schaumberger, Simone; Nagl, Veronika; Hessenberger, Sabine; Schatzmayr, Gerd

    2015-01-01

    Laminitis is one of the most common diseases in horses. It is not only painful for the animal, but also has a significant financial impact on the equine industry. This multifactorial disease affects the connective tissue of the hoof. However, the pathogenesis of laminitis is still not fully understood. Endotoxins, also known as lipopolysaccharides (LPS), and bacterial exotoxins seem to play an important role during the development of laminitis. The aim of our study was to investigate the effect of increasing LPS concentrations (0, 2.5, 5, 10, and 100 μg/mL) on cell viability of isolated epidermal and dermal hoof cells as well as on the tissue integrity of hoof explants. Furthermore, glucose, acetic acid, lactic acid, and propionic acid concentrations in explant supernatants were measured to evaluate the energy metabolism in the hoof tissue. LPS did not exhibit cytotoxic effects on epidermal or dermal cells. Force required to separate LPS treated hoof explants decreased in a concentration dependent manner. Specifically, explants incubated with 10 and 100 μg/mL needed significantly less force to separate compared to control explants. Lactic acid concentrations were significantly decreased in explants incubated with 5, 10, or 100 μg/mL LPS, while glucose, acetic acid and propionic acid concentrations were unaffected by LPS treatment. Our study indicates that LPS has no cytotoxic effect on epidermal and dermal cells isolated from hoof tissue, but impairs integrity of hoof explants. In addition, LPS led to an alteration of the lactic acid production in the lamellar tissue. Since our data highlight that LPS can affect the integrity of the equine hoof tissue in vitro, endotoxins should be further explored for their contribution to facilitate the development of laminitis. PMID:26599864

  18. Benzylidene Acetal Protecting Group as Carboxylic Acid Surrogate: Synthesis of Functionalized Uronic Acids and Sugar Amino Acids.

    PubMed

    Banerjee, Amit; Senthilkumar, Soundararasu; Baskaran, Sundarababu

    2016-01-18

    Direct oxidation of the 4,6-O-benzylidene acetal protecting group to C-6 carboxylic acid has been developed that provides an easy access to a wide range of biologically important and synthetically challenging uronic acid and sugar amino acid derivatives in good yields. The RuCl3 -NaIO4 -mediated oxidative cleavage method eliminates protection and deprotection steps and the reaction takes place under mild conditions. The dual role of the benzylidene acetal, as a protecting group and source of carboxylic acid, was exploited in the efficient synthesis of six-carbon sialic acid analogues and disaccharides bearing uronic acids, including glycosaminoglycan analogues.

  19. Escherichia coli and Salmonella enterica are protected against acetic acid, but not hydrochloric acid, by hypertonicity.

    PubMed

    Chapman, B; Ross, T

    2009-06-01

    Chapman et al. (B. Chapman, N. Jensen, T Ross, and M. B. Cole, Appl. Environ. Microbiol. 72:5165-5172, 2006) demonstrated that an increased NaCl concentration prolongs survival of Escherichia coli O157 SERL 2 in a broth model simulating the aqueous phase of a food dressing or sauce containing acetic acid. We examined the responses of five other E. coli strains and four Salmonella enterica strains to increasing concentrations of NaCl under conditions of lethal acidity and observed that the average "lag" time prior to inactivation decreases in the presence of hydrochloric acid but not in the presence of acetic acid. For E. coli in the presence of acetic acid, the lag time increased with increasing NaCl concentrations up to 2 to 4% at pH 4.0, up to 4 to 6% at pH 3.8, and up to 4 to 7% (wt/wt of water) NaCl at pH 3.6. Salmonella was inactivated more rapidly by combined acetic acid and NaCl stresses than E. coli, but increasing NaCl concentrations still decreased the lag time prior to inactivation in the presence of acetic acid; at pH 4.0 up to 1 to 4% NaCl was protective, and at pH 3.8 up to 1 to 2% NaCl delayed the onset of inactivation. Sublethal injury kinetics suggest that this complex response is a balance between the lethal effects of acetic acid, against which NaCl is apparently protective, and the lethal effects of the NaCl itself. Compared against 3% NaCl, 10% (wt/wt of water) sucrose with 0.5% NaCl (which has similar osmotic potential) was found to be equally protective against adverse acetic acid conditions. We propose that hypertonicity may directly affect the rate of diffusion of acetic acid into cells and hence cell survival.

  20. Direct lactic acid fermentation of Jerusalem artichoke tuber extract using Lactobacillus paracasei without acidic or enzymatic inulin hydrolysis.

    PubMed

    Choi, Hwa-Young; Ryu, Hee-Kyoung; Park, Kyung-Min; Lee, Eun Gyo; Lee, Hongweon; Kim, Seon-Won; Choi, Eui-Sung

    2012-06-01

    Lactic acid fermentation of Jerusalem artichoke tuber was performed with strains of Lactobacillus paracasei without acidic or enzymatic inulin hydrolysis prior to fermentation. Some strains of L. paracasei, notably KCTC13090 and KCTC13169, could ferment hot-water extract of Jerusalem artichoke tuber more efficiently compared with other Lactobacillus spp. such as L. casei type strain KCTC3109. The L. paracasei strains could utilize almost completely the fructo-oligosaccharides present in Jerusalem artichoke. Inulin-fermenting L. paracasei strains produced c.a. six times more lactic acid compared with L. casei KCTC3109. Direct lactic fermentation of Jerusalem artichoke tuber extract at 111.6g/L of sugar content with a supplement of 5 g/L of yeast extract by L. paracasei KCTC13169 in a 5L jar fermentor produced 92.5 ce:hsp sp="0.25"/>g/L of lactic acid with 16.8 g/L fructose equivalent remained unutilized in 72 h. The conversion efficiency of inulin-type sugars to lactic acid was 98% of the theoretical yield.

  1. Plasmids from Food Lactic Acid Bacteria: Diversity, Similarity, and New Developments.

    PubMed

    Cui, Yanhua; Hu, Tong; Qu, Xiaojun; Zhang, Lanwei; Ding, Zhongqing; Dong, Aijun

    2015-06-10

    Plasmids are widely distributed in different sources of lactic acid bacteria (LAB) as self-replicating extrachromosomal genetic materials, and have received considerable attention due to their close relationship with many important functions as well as some industrially relevant characteristics of the LAB species. They are interesting with regard to the development of food-grade cloning vectors. This review summarizes new developments in the area of lactic acid bacteria plasmids and aims to provide up to date information that can be used in related future research.

  2. Biodegradability and biocompatibility study of poly(chitosan-g-lactic acid) scaffolds.

    PubMed

    Zhang, Zhe; Cui, Huifei

    2012-03-14

    A biodegradable, biocompatible poly(chitosan-g-lactic acid) (PCLA) scaffold was prepared and evaluated in vitro and in vivo. The PCLA scaffold was obtained by grafting lactic acid (LA) onto the amino groups on chitosan (CS) without a catalyst. The PCLA scaffolds were characterized by Fourier Transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The biodegradabilty was determined by mass loss in vitro, and degradation in vivo as a function of feed ratio of LA/CS. Bone marrow mesenchymal stem cell (BMSC) culture experiments and histological examination were performed to evaluate the PCLA scaffolds' biocompatibility. The results indicated that PCLA was promising for tissue engineering application.

  3. Probiotic lactic acid bacteria – the fledgling cuckoos of the gut?

    PubMed Central

    Berstad, Arnold; Raa, Jan; Midtvedt, Tore; Valeur, Jørgen

    2016-01-01

    It is tempting to look at bacteria from our human egocentric point of view and label them as either ‘good’ or ‘bad’. However, a microbial society has its own system of government – ‘microcracy’ – and its own rules of play. Lactic acid bacteria are often referred to as representatives of the good ones, and there is little doubt that those belonging to the normal intestinal flora are beneficial for human health. But we should stop thinking of lactic acid bacteria as always being ‘friendly’ – they may instead behave like fledgling cuckoos. PMID:27235098

  4. Plasmids from Food Lactic Acid Bacteria: Diversity, Similarity, and New Developments

    PubMed Central

    Cui, Yanhua; Hu, Tong; Qu, Xiaojun; Zhang, Lanwei; Ding, Zhongqing; Dong, Aijun

    2015-01-01

    Plasmids are widely distributed in different sources of lactic acid bacteria (LAB) as self-replicating extrachromosomal genetic materials, and have received considerable attention due to their close relationship with many important functions as well as some industrially relevant characteristics of the LAB species. They are interesting with regard to the development of food-grade cloning vectors. This review summarizes new developments in the area of lactic acid bacteria plasmids and aims to provide up to date information that can be used in related future research. PMID:26068451

  5. Recent advances in nitrogen-fixing acetic acid bacteria.

    PubMed

    Pedraza, Raúl O

    2008-06-30

    Nitrogen is an essential plant nutrient, widely applied as N-fertilizer to improve yield of agriculturally important crops. An interesting alternative to avoid or reduce the use of N-fertilizers could be the exploitation of plant growth-promoting bacteria (PGPB), capable of enhancing growth and yield of many plant species, several of agronomic and ecological significance. PGPB belong to diverse genera, including Azospirillum, Azotobacter, Herbaspirillum, Bacillus, Burkholderia, Pseudomonas, Rhizobium, and Gluconacetobacter, among others. They are capable of promoting plant growth through different mechanisms including (in some cases), the biological nitrogen fixation (BNF), the enzymatic reduction of the atmospheric dinitrogen (N(2)) to ammonia, catalyzed by nitrogenase. Aerobic bacteria able to oxidize ethanol to acetic acid in neutral or acid media are candidates of belonging to the family Acetobacteraceae. At present, this family has been divided into ten genera: Acetobacter, Gluconacetobacter, Gluconobacter, Acidomonas, Asaia, Kozakia, Saccharibacter, Swaminathania, Neoasaia, and Granulibacter. Among them, only three genera include N(2)-fixing species: Gluconacetobacter, Swaminathania and Acetobacter. The first N(2)-fixing acetic acid bacterium (AAB) was described in Brazil. It was found inside tissues of the sugarcane plant, and first named as Acetobacter diazotrophicus, but then renamed as Gluconacetobacter diazotrophicus. Later, two new species within the genus Gluconacetobacter, associated to coffee plants, were described in Mexico: G. johannae and G. azotocaptans. A salt-tolerant bacterium named Swaminathania salitolerans was found associated to wild rice plants. Recently, N(2)-fixing Acetobacter peroxydans and Acetobacter nitrogenifigens, associated with rice plants and Kombucha tea, respectively, were described in India. In this paper, recent advances involving nitrogen-fixing AAB are presented. Their natural habitats, physiological and genetic aspects

  6. Genome Sequence of Lactobacillus rhamnosus Strain CASL, an Efficient l-Lactic Acid Producer from Cheap Substrate Cassava

    PubMed Central

    Yu, Bo; Su, Fei; Wang, Limin; Zhao, Bo; Qin, Jiayang; Ma, Cuiqing; Xu, Ping; Ma, Yanhe

    2011-01-01

    Lactobacillus rhamnosus is a type of probiotic bacteria with industrial potential for l-lactic acid production. We announce the draft genome sequence of L. rhamnosus CASL (2,855,156 bp with a G+C content of 46.6%), which is an efficient producer of l-lactic acid from cheap, nonfood substrate cassava with a high production titer. PMID:22123765

  7. Survival of heated Bacillus coagulans spores in a medium acidified with lactic or citric acid.

    PubMed

    Palop, A; Marco, A; Raso, J; Sala, F J; Condón, S

    1997-08-19

    The influence of the intensity of heat treatments on the capacity of citric or lactic acid to prevent growth of survivors of Bacillus coagulans spores after 10 days storage at 35 degrees C was studied. In most cases, the number of survivors during storage decreased. The extent of this spore inactivation depended on the intensity of previous heat treatment and the pH of the medium and the acidulant used. The inactivating effect of storage was pronounced even at pH values less acidic than those used by the canning industry. Citric acid was more effective than lactic acid on spores given only low heat treatments, but lactic was more effective against those given more severe heat treatments. The severity of heat treatment required for lactic to be more effective than citric acid increased with pH of the medium. Heat treatment also required increased pH for heated spores to grow. pH 4.6, regardless of acidulant used, was unable to prevent growth of unheated spores but a less acidic pH (pH 5.2) did prevent growth even when spores had been given only mild heat treatments (10 s at 100 degrees C).

  8. Effect of acetic acid on lipid accumulation by glucose-fed activated sludge cultures

    SciTech Connect

    Mondala, Andro; Hernandez, Rafael; French, Todd; McFarland, Linda; Sparks, Darrell; Holmes, William; Haque, Monica

    2012-01-01

    The effect of acetic acid, a lignocellulose hydrolysis by-product, on lipid accumulation by activated sludge cultures grown on glucose was investigated. This was done to assess the possible application of lignocellulose as low-cost and renewable fermentation substrates for biofuel feedstock production. Results: Biomass yield was reduced by around 54% at a 2 g L -1 acetic acid dosage but was increased by around 18% at 10 g L -1 acetic acid dosage relative to the control run. The final gravimetric lipid contents at 2 and 10 g L -1 acetic acid levels were 12.5 + 0.7% and 8.8 + 3.2% w/w, respectively, which were lower than the control (17.8 + 2.8% w/w). However, biodiesel yields from activated sludge grown with acetic acid (5.6 + 0.6% w/w for 2 g L -1 acetic acid and 4.2 + 3.0% w/w for 10 g L -1 acetic acid) were higher than in raw activated sludge (1-2% w/w). The fatty acid profiles of the accumulated lipids were similar with conventional plant oil biodiesel feedstocks. Conclusions: Acetic acid enhanced biomass production by activated sludge at high levels but reduced lipid production. Further studies are needed to enhance acetic acid utilization by activated sludge microorganisms for lipid biosynthesis.

  9. Improvement in HPLC separation of acetic acid and levulinic acid in the profiling of biomass hydrolysate.

    PubMed

    Xie, Rui; Tu, Maobing; Wu, Yonnie; Adhikari, Sushil

    2011-04-01

    5-Hydroxymethylfurfural (HMF) and furfural could be separated by the Aminex HPX-87H column chromatography, however, the separation and quantification of acetic acid and levulinic acid in biomass hydrolysate have been difficult with this method. In present study, the HPLC separation of acetic acid and levulinic acid on Aminex HPX-87H column has been investigated by varying column temperature, flow rate, and sulfuric acid content in the mobile phase. The column temperature was found critical in resolving acetic acid and levulinic acid. The resolution for two acids increased dramatically from 0.42 to 1.86 when the column temperature was lowered from 60 to 30 °C. So did the capacity factors for levulinic acid that was increased from 1.20 to 1.44 as the column temperature dropped. The optimum column temperature for the separation was found at 45 °C. Variation in flow rate and sulfuric acid concentration improved not as much as the column temperature did.

  10. Transcript and metabolite alterations increase ganoderic acid content in Ganoderma lucidum using acetic acid as an inducer.

    PubMed

    Ren, Ang; Li, Xiong-Biao; Miao, Zhi-Gang; Shi, Liang; Jaing, Ai-Liang; Zhao, Ming-Wen

    2014-12-01

    Acetic acid at 5-8 mM increased ganoderic acid (GA) accumulation in Ganoderma lucidum. After optimization by the response surface methodology, the GA content reached 5.5/100 mg dry weight, an increase of 105% compared with the control. The intermediate metabolites of GA biosynthesis, lanosterol and squalene also increased to 47 and 15.8 μg/g dry weight, respectively, in response to acetic acid. Acetic acid significantly induced transcription levels of sqs, lano, hmgs and cyp51 in the GA biosynthesis pathway. An acetic acid-unregulated acetyl coenzyme A synthase (acs) gene was selected from ten candidate homologous acs genes. The results indicate that acetic acid alters the expression of genes related to acetic acid assimilation and increases GA biosynthesis and the metabolic levels of lanosterol, squalene and GA-a, thereby resulting in GA accumulation.

  11. Corrosion behavior of mild steel in acetic acid solutions

    SciTech Connect

    Singh, M.M.; Gupta, A.

    2000-04-01

    The corrosion behavior of mild steel in acetic acid (CH{sub 3}COOH) solutions was studied by weight loss and potentiostatic polarization techniques. The variation in corrosion rate of mild steel with concentrations of CH{sub 3}COOH, evaluated by weight loss and electrochemical techniques, showed marked resemblance. From both techniques, the maximum corrosion rate was observed for 20% CH{sub 3}COOH solution at all three experimental temperatures (25, 35, and 45 C). Anodic polarization curves showed active-passive behavior at each concentration, except at 80% CH{sub 3}COOH. Critical current density (i{sub c}) passive current density (I{sub n}), primary passivation potential (E{sub pp}), and potential for passivity (E{sub p}) had their highest values in 20% CH{sub 3}COOH solution. With an increase in temperature, while the anodic polarization curves shifted toward higher current density region at each concentration, the passive region became progressively less distinguishable. With the addition of sodium acetate (NaCOOCH{sub 3}) as a supporting electrolyte, the passive range was enlarged substantially. However, the transpassive region commenced at more or less the same potential. Cathodic polarization curves were almost identical irrespective of the concentration of CH{sub 3}COOH or temperature.

  12. Can the development and autolysis of lactic acid bacteria influence the cheese volatile fraction? The case of Grana Padano.

    PubMed

    Lazzi, Camilla; Povolo, Milena; Locci, Francesco; Bernini, Valentina; Neviani, Erasmo; Gatti, Monica

    2016-09-16

    In this study, the relationship between the dynamics of the growth and lysis of lactic acid bacteria in Grana Padano cheese and the formation of the volatile flavor compounds during cheese ripening was investigated. The microbial dynamics of Grana Padano cheeses that were produced in two different dairies were followed during ripening. The total and cultivable lactic microflora, community composition as determined by length heterogeneity-PCR (LH-PCR), and extent of bacterial lysis using an intracellular enzymatic activity assay were compared among cheeses after 2, 6 and 13months of ripening in two dairies. The evolution of whole and lysed microbiota was different between the two dairies. In dairy 2, the number of total cells was higher than that in dairy 1 in all samples, and the number of cells that lysed during ripening was lower. In addition, at the beginning of ripening (2months), the community structure of the cheese from dairy 2 was more complex and was composed of starter lactic acid bacteria (Lactobacillus helveticus and Lactobacillus delbrueckii) and NSLAB, possibly arising from raw milk, including Lactobacillus rhamnosus/Lactobacillus casei and Pediococcus acidilactici. On the other hand, the cheese from dairy 1 that ripened for 2months was mainly composed of the SLAB L. helveticus and L. delbrueckii. An evaluation of the free-DNA fraction through LH-PCR identified those species that had a high degree of lysis. Data on the dynamics of bacterial growth and lysis were evaluated with respect to the volatile profile and the organic acid content of the two cheeses after 13months of ripening, producing very different results. Cheese from dairy 1 showed a higher content of free fatty acids, particularly those deriving from milk fat lipolysis, benzaldehyde and organic acids, such as pGlu and citric. In contrast, cheese from dairy 2 had a greater amount of ketones, alcohols, hydrocarbons, acetic acid and propionic acid. Based on these results, we can conclude that

  13. Fabrication and characterization of novel multilayered structures by stereocomplexion of poly(D-lactic acid)/poly(L-lactic acid) and self-assembly of polyelectrolytes

    PubMed Central

    Yang, Gesheng; Pastorino, Laura

    2016-01-01

    Summary The enantiomers poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) were alternately adsorbed directly on calcium carbonate (CaCO3) templates and on poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) multilayer precursors in order to fabricate a novel layer-by-layer (LBL) assembly. A single layer of poly(L-lysine) (PLL) was used as a linker between the (PDLA/PLLA)n stereocomplex and the cores with and without the polymeric (PSS/PAH)n/PLL multilayer precursor (PEM). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) were used to characterize the chemical composition and molecular weight of poly(lactic acid) polymers. Both multilayer structures, with and without polymeric precursor, were firstly fabricated and characterized on planar supports. A quartz crystal microbalance (QCM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and ellipsometry were used to evaluate the thickness and mass of the multilayers. Then, hollow, spherical microcapsules were obtained by the removal of the CaCO3 sacrificial template. The chemical composition of the obtained microcapsules was confirmed by differential scanning calorimetry (DSC) and wide X-ray diffraction (WXRD) analyses. The microcapsule morphology was evaluated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) measurements. The experimental results confirm the successful fabrication of this innovative system, and its full biocompatibility makes it worthy of further characterization as a promising drug carrier for sustained release. PMID:26925356

  14. [The ultrafiltration at pre-analytical stage under detection of concentration of lactic acid in blood plasma].

    PubMed

    Alekseevskaia, E S; Zhloba, A A; Subbotina, T F

    2013-11-01

    The detection of concentration of lactic acid in blood plasma and other objects is especially applied to discover the mitochondria dysfunctions. The study was organized to analyze samplings of blood plasma and plasma ultra-filtrates taken from 80 healthy persons and 73 patients with activation of intravascular coagulation and fibrinolysis using lactate-oxidase test. The comparative analysis of results of detection of concentrations of lactic acid in blood plasma and its ultra-filtrate established that in 72% of cases the higher values of concentration of detecting lactic acid took place after procedure of ultra-filtration enabling separation of overwhelming quantity of protein. In accordance with accumulated experience in the field of clinical diagnostic practice the enzyme tests are to be applied to detect the concentration of lactic acid in blood plasma and other objects. The present study demonstrated the expediency of application of plasma ultra-filtrate to detect the concentration of lactic acid.

  15. Solid phase extraction of lactic acid from fermentation broth by anion-exchangeable silica confined ionic liquids.

    PubMed

    Bi, Wentao; Zhou, Jun; Row, Kyung Ho

    2011-01-15

    Three anion-exchangeable, silica-confined ionic liquids were synthesized for solid phase extraction of lactic acid from fermentation broth, followed by high-performance liquid chromatography coupled to ultraviolet detection. By comparing the adsorption isotherms of lactic acid on different silica-confined ionic liquids, interactions between the lactic acid and sorbents were investigated. The adsorbed amounts were then fitted into different adsorption isotherm equations; finally, the Langmuir equation was selected. Then the imidazolium silica with the highest adsorption capacity of lactic acid was packed into a cartridge for solid phase extraction. The loading volume of the cartridge was optimized by the Langmuir equation and geometry. After washing with distilled water and eluting with 0.25 mol L(-1) of an HCl solution, the lactic acid was separated from interference with a recovery yield of 91.9%. Furthermore, this kind of anion-exchangeable material exhibited potential for industrial applications and separation of other anionic bioactive compounds.

  16. Development of Acetic Acid Removal Technology for the UREX+Process

    SciTech Connect

    Robert M. Counce; Jack S. Watson

    2009-06-30

    It is imperative that acetic acid is removed from a waste stream in the UREX+process so that nitric acid can be recycled and possible interference with downstreatm steps can be avoidec. Acetic acid arises from acetohydrozamic acid (AHA), and is used to suppress plutonium in the first step of the UREX+process. Later, it is hydrolyzed into hydroxyl amine nitrate and acetic acid. Many common separation technologies were examined, and solvent extraction was determined to be the best choice under process conditions. Solvents already used in the UREX+ process were then tested to determine if they would be sufficient for the removal of acetic acid. The tributyl phosphage (TBP)-dodecane diluent, used in both UREX and NPEX, was determined to be a solvent system that gave sufficient distribution coefficients for acetic acid in addition to a high separation factor from nitric acid.

  17. Synthesis and characterization of acetic acid and ethanoic acid (based)-maleimide

    NASA Astrophysics Data System (ADS)

    Poad, Siti Nashwa Mohd; Hassan, Nurul Izzaty; Hassan, Nur Hasyareeda

    2016-11-01

    A new route to the synthesis of maleimide is described. 2-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)acetic acid maleimide (1) and 2-(4-(2,5-Dioxo-2,5-dihydro- 1H-pyrrol-1-yl)phenyl)ethanoic acid maleimide (2) have been synthesized by the reaction of maleic anhydride with glycine and 4-aminophenyl acetic aicd. Maleimide (1) was synthesized by conventional technique while maleimide (2) was synthesized by microwave method. The compounds were characterized using FT-Infrared (FT-IR), 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopies and Mass Spectrometry.

  18. Crystal structure of 7,8-benzocoumarin-4-acetic acid.

    PubMed

    Swamy, R Ranga; Gowda, Ramakrishna; Gowda, K V Arjuna; Basanagouda, Mahantesha

    2015-08-01

    The fused-ring system in the title compound [systematic name: 2-(2-oxo-2H-benzo[h]chromen-4-yl)acetic acid], C15H10O4, is almost planar (r.m.s. deviation = 0.031 Å) and the Car-C-C=O (ar = aromatic) torsion angle for the side chain is -134.4 (3)°. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds, generating [100] C(8) chains, where the acceptor atom is the exocyclic O atom of the fused-ring system. The packing is consolidated by a very weak C-H⋯O hydrogen bond to the same acceptor atom. Together, these inter-actions lead to undulating (001) layers in the crystal.

  19. The Ground and First Excited Torsional States of Acetic Acid.

    PubMed

    Ilyushin, V. V.; Alekseev, E. A.; Dyubko, S. F.; Podnos, S. V.; Kleiner, I.; Margulès, L.; Wlodarczak, G.; Demaison, J.; Cosléou, J.; Maté, B.; Karyakin, E. N.; Golubiatnikov, G. Yu.; Fraser, G. T.; Suenram, R. D.; Hougen, J. T.

    2001-02-01

    A global fit of microwave and millimeter-wave rotational transitions in the ground and first excited torsional states (v(t) = 0 and 1) of acetic acid (CH(3)COOH) is reported, which combines older measurements from the literature with new measurements from Kharkov, Lille, and NIST. The fit uses a model developed initially for acetaldehyde and methanol-type internal rotor molecules. It requires 34 parameters to achieve a unitless weighted standard deviation of 0.84 for a total of 2518 data and includes A- and E-species transitions with J

  20. Transcriptome analysis of acetic-acid-treated yeast cells identifies a large set of genes whose overexpression or deletion enhances acetic acid tolerance.

    PubMed

    Lee, Yeji; Nasution, Olviyani; Choi, Eunyong; Choi, In-Geol; Kim, Wankee; Choi, Wonja

    2015-08-01

    Acetic acid inhibits the metabolic activities of Saccharomyces cerevisiae. Therefore, a better understanding of how S. cerevisiae cells acquire the tolerance to acetic acid is of importance to develop robust yeast strains to be used in industry. To do this, we examined the transcriptional changes that occur at 12 h post-exposure to acetic acid, revealing that 56 and 58 genes were upregulated and downregulated, respectively. Functional categorization of them revealed that 22 protein synthesis genes and 14 stress response genes constituted the largest portion of the upregulated and downregulated genes, respectively. To evaluate the association of the regulated genes with acetic acid tolerance, 3 upregulated genes (DBP2, ASC1, and GND1) were selected among 34 non-protein synthesis genes, and 54 viable mutants individually deleted for the downregulated genes were retrieved from the non-essential haploid deletion library. Strains overexpressing ASC1 and GND1 dis