Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LACTIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources
PubMed2026

Fructophilic lactic acid bacteria as a window into multi-scale convergent evolution.

Fructophilic lactic acid bacteria (FLAB) are a group of lactic acid bacteria with unique growth characteristics, that is, poor growth on glucose. Their growth is enhanced in the presence of fructose or external electron acceptors. These organisms inhabit fructose-rich environments such as flowers, fruits, and pollinating insects, particularly honey bees. Apilactobacillus spp. and Fructobacillus spp. are representatives of FLAB, although they belong to phylogenetically distant clades. These organisms commonly possess markedly small genomes with a low number of coding DNA sequences. Furthermore, their genomes are characterized by a markedly reduced number of genes involved in carbohydrate transport and metabolism. Genome reduction in FLAB reflects convergent adaptation to fructose-rich environments rather than general genome streamlining. The two distinct FLAB genera, Fructobacillus and Apilactobacillus, independently lost more than 100 genes in statistically similar orders. In contrast, genes involved in carbohydrate and amino acid metabolism exhibited reversed orders of loss between the two genera. Furthermore, FLAB genomes lack an intact bifunctional alcohol/aldehyde dehydrogenase gene (adhE), which causes their poor growth on glucose. A comparative genomic study suggested the evolutionary process underlying adhE gene decay during adaptation to the fructose-rich environments, including pollinating insects. In conclusion, FLAB represent a unique example of habitat-driven convergent reductive evolution that can be investigated across multiple biological scales - from individual genes to whole genomes - in the diverse LAB group with a wide range of habitats, and partially share the fructophilic evolution with eukaryotic yeasts found in fructose-rich habitats.

Fructose↗
PubMed2005

Bioconversion of kitchen garbage to lactic acid by two wild strains of Lactobacillus species.

To enhance lactic acid (LA) production from kitchen garbage, which is a raw material for biodegradable plastics production, the application of high-performance lactic acid bacteria (LAB) as inocula was investigated. Two wild strains of Lactobacillus species, designated as TH165 and TD175, were isolated and screened from kitchen garbage. Strain TH165 was capable of hydrolyzing starch to produce LA; 49.5% of starch was broken down in fermentation medium containing 8.52 g/L of soluble starch, and 4.01 g/L of LA was produced after 24 h fermentation at 37 degrees C without pH control. Strain TD175 could produce 16.06 g/L of LA, 66.9% higher than that of Lactobacillus bulgaricus ACCC11058 in fermentation medium containing 2.0% glucose at 30 degrees C without pH control. Furthermore, coinoculation of strains TH165 and TD175 enhanced the LA production, resulting in 33.80 g/L of LA concentration and 0.46 g/g (DW) of LA yield from nonautoclaved kitchen garbage after 72 h fermentation with pH maintained at 5.5-6.0, values 36.9% higher than those of the fermentation without inoculum (control). This study shows that enhancement of LA production from kitchen garbage can be realized by using high-performance LAB. This recycling system is conducive to clear away pollutants and to reduce cost of LA production.

Biodegradation, Environmental↗
PubMed1984

Reflex increases in heart-rate induced by perfusing the hind leg of the rat with solutions containing lactic acid.

The hypothesis that metabolic receptors in skeletal muscle influence heart-rate during exercise was tested by means of a perfused preparation of the rat's hind legs. The isolated leg was connected to the body only by nerve and bone and was perfused with tyrode solution. The humoral changes of exercise were simulated by perfusing with modified tyrode solutions in which concentration of K+, osmolality, concentrations of lactic acid, and inorganic phosphate were changed to reflect to those occurring during heavy exercise. Only perfusion with a solution enriched with lactic acid elicited a significant increase in heart-rate. The response disappeared when the nerve supply to the leg was cooled or sectioned. 20-60 s after the start of perfusion with solution of high [lactic acid] heart-rate began to increase reaching a maximum (delta HR +/- SE = 20.2 +/- 8.2, n = 7) after about 2 min. The effect on heart-rate increased when the venous concentration of lactic acid was increased the range from 3 to 10 mmol/l. In further experiments, we tried to separate the effects of pH and lactate. Heart-rate responses were induced only at low pH and at low pH the extent to which heart-rate changed increased with increases in lactate concentration.

Animals↗
PubMed1978

PUlmonary alveolar proteinosis: shunt fraction and lactic acid dehydrogenase concentration as aids to diagnosis.

The shunt fraction breathing 100 per cent O2 and serum lactic acid dehydrogenase concentration were evaluated as 2 easily obtainable, rapid laboratory procedures that might aid in the early diagnosis of pulmonary alveolar proteinosis. The mean +/- SE shunt fraction was 20 +/- 1.2 per cent in patients with alveolar proteinosis compared to 8.9 +/- 0.5 per cent in other groups of patients with diffuse lung disease (P less than 0.001). The lactic acid dehydrogenase concentration was increased in all patients with alveolar proteinosis and helped to separate further the 2 groups. Thus, when a patient presents with the findings of chronic diffuse lung disease, the lactic acid dehydrogenase concentration and the shunt fraction can be of value in suggesting the diagnosis of pulmonary alveolar proteinosis.

Biopsy↗
PubMed2004

Effect of culture conditions on lactic acid production of Tetragenococcus species.

AIMS: To investigate the effects of the salt concentration, incubation temperature and initial pH of the medium on the fermentative ability of the halophilic lactic acid bacteria, Tetragenococcus muriaticus and T. halophilus. METHOD AND RESULTS: The growth, lactic acid production and pH reduction ability of five strains of T. muriaticus and T. halophilus in MRS broth medium under various culture conditions such as salt concentration (3, 7, 15 and 23% NaCl), temperature (20, 30 and 40 degrees C), and initial medium pH (5.8, 6.5 and 7.5) were investigated. Those of T. halophilus were seriously affected by a high salinity (23% NaCl); in contrast, those of T. muriaticus were affected by a low initial pH (5.8). CONCLUSIONS: The results indicate that high saline concentrations and low pH values have significant impact on the growth, lactic acid production and pH reduction ability of T. halophilus and T. muriaticus, respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: This study appears to be important in biopreservation during the manufacture of fermented food products. Both T. muriaticus and T. halophilus may support each other in reducing pH in hypersaline or low pH environment. To our knowledge, this is the first report on the fermentation ability of T. muriaticus.

Dose-Response Relationship, Drug↗
PubMed2001

Protective effects of lactic acid on force production in rat skeletal muscle.

1. During strenuous exercise lactic acid accumulates producing a reduction in muscle pH. In addition, exercise causes a loss of muscle K(+) leading to an increased concentration of extracellular K(+) ([K(+)](o)). Individually, reduced pH and increased [K(+)](o) have both been suggested to contribute to muscle fatigue. 2. To study the combined effect of these changes on muscle function, isolated rat soleus muscles were incubated at a [K(+)](o) of 11 mM, which reduced tetanic force by 75 %. Subsequent addition of 20 mM lactic acid led, however, to an almost complete force recovery. A similar recovery was observed if pH was reduced by adding propionic acid or increasing the CO(2) tension. 3. The recovery of force was associated with a recovery of muscle excitability as assessed from compound action potentials. In contrast, acidification had no effect on the membrane potential or the Ca(2+) handling of the muscles. 4. It is concluded that acidification counteracts the depressing effects of elevated [K(+)](o) on muscle excitability and force. Since intense exercise is associated with increased [K(+)](o), this indicates that, in contrast to the often suggested role for acidosis as a cause of muscle fatigue, acidosis may protect against fatigue. Moreover, it suggests that elevated [K(+)](o) is of less importance for fatigue than indicated by previous studies on isolated muscles.

Animals↗
PubMed1996

Thermotolerance of meat spoilage lactic acid bacteria and their inactivation in vacuum-packaged vienna sausages.

Heat resistance of three meat spoilage lactic acid bacteria was determined in vitro. D-values at 57, 60 and 63 degrees C were 52.9, 39.3 and 32.5 s for Lactobacillus sake, 34.9, 31.3 and 20.2 s for Leuconostoc mesenteroides and 22.5, 15.6 and 14.4 s for Lactobacillus curvatus, respectively. The three lactic acid bacteria were heat sensitive, as one log reductions in numbers were achieved at 57 degrees C in less than 60 s. Z-values could not be accurately determined as D-values did not change by a factor of 10 over the temperature range studied. In-package pasteurization processes were calculated using the highest in vitro D-value and applied to vacuum-packaged vienna sausages. Microbiological shelf life (time for lactic acid bacteria count to reach 5 x 10(6) CFU/g) increased from 7 days for non-pasteurized samples to 67, 99 and 119 days for samples of the three pasteurization treatments at 8 degrees C storage. Enterobacteriaceae were detected at levels of log 4.0 CFU/g in non-pasteurized samples, but were reduced to < log 1.0 CFU/g in pasteurized samples. The incidence of listeriae in non-pasteurized samples was low as only one Listeria innocua strain was isolated. No Listeria spp. were isolated from pasteurized samples. Numbers of Clostridium isolates increased from one in non-pasteurized samples to 25 in pasteurized samples. Increasing incidences of clostridia, and the presence of C. perfringens in pasteurized samples indicated that in-package pasteurization could compromise product safety.

Clostridium↗
PubMedDate not supplied

Stereocomplex formation by enantiomeric poly(lactic acid) graft-type phospholipid polymers for tissue engineering.

A porous scaffold as a cell-compatible material was designed and prepared using a phospholipid copolymer composed of 2-methacryloyloxyethyl phosphorylcholine (MPC), n-butyl methacrylate, and enantiomeric macromonomers, the poly(L-lactic acid) (PLLA) macromonomer, and poly(D-lactic acid) (PDLA) macromonomer. On the basis of the wide-angle X-ray diffraction and differential scanning calorimetry measurements, the formation of a stereocomplex between the PLLA and PDLA segments of the copolymer was observed on the porous scaffold. The porous structure was prepared by a sodium chloride leaching technique, and the pore was linked to the scaffold. The pore size was confirmed by scanning electron microscopy and found to be ca. 200 microm. These observations suggest that the porous scaffold makes it possible to produce cell-compatible materials, which may involve the following advantages for tissue engineering: (i) cell compatibility using phospholipid copolymer, (ii) adequate cell adhesion by poly(lactic acid), and (iii) complete disappearance of scaffold by dissociation of stereocomplex. The cell experiment using the porous scaffold will be the next subject and reported in a forthcoming paper.

Biocompatible Materials↗
PubMed2001

Synthesis of 2-O-(4-coumaroyl)-3-(4-hydroxyphenyl)lactic acid, an important intermediate of rosmarinic acid biosynthesis.

A simple method to synthesize (+/-)-2-O-(4-coumaroyl)-3-(4-hydroxyphenyl)lactic acid (1), a key intermediate in rosmarinic acid biosynthesis in higher plant cells, was established by condensation of protected 4-coumaric acid and (+/-)-3-(4-hydroxyphenyl)lactic acid followed by deprotection. A stable supply of 1 thus attained will lead to biochemical and molecular biological characterization of later steps of rosmarinic acid biosynthesis.

Cinnamates↗
PubMed2001

The synergistic effect of lactic acid bacteria and alkylglycerols on humoral immunity in mice.

Investigations on immune suppression and reconstitution of immune functions dependent on the presence of physiological microflora allow us to conclude that symbiotic microorganisms such as Lactobacillus sp. are essential for adequate activity of the defense system in humans. In addition to their beneficial influence on the intestinal microbial balance, these microorganisms exert a variety of immunomodulatory effects on the host immune system. On the other hand, immunostimulatory animal-derived substances rich in alkylglycerols have been shown to enhance lactic acid bacteria proliferation. Therefore, the aim of the present study was to evaluate the effects on murine humoral response of the combined administration of lyophilized combination of three lactic acid bacteria: L. acidophilus, L. bulgaricus and Bifidobacterium bifidum together with alkylglycerol-rich shark liver oil. The lactic acid bacteria mixture induced markedly stronger enhancement of the humoral response than alkylglycerols did. A significant synergistic stimulatory effect of lactic acid bacteria and alkylglycerols was observed in both treatment schedules: post- as well as in preimmunization with sheep red blood cells. However, their concomitant administration exerted stronger immunomodulatory effect than did the alternative route of treatment.

Animals↗
PubMed2000

Synthesis of acrylate functional telechelic poly(lactic acid) oligomer by transesterification.

The controlled synthesis of low molecular weight (Mn from 700 to 10 000 g/mol) poly(lactic acid) (PLA) telechelic oligomers end-capped with acrylate groups by a one-step reaction was investigated. A transesterification reaction was carried out in solution with a Lewis acid titanium catalyst using a high molecular weight PLA and a low molar mass diacrylate. End-functionalization was demonstrated by proton NMR spectroscopy which was also used for quantitative analysis and number average molecular weight determination using the ratio between the acrylic chain ends to the main groups of poly(D,L-lactic acid). The formation of low molar mass oligomers from high molecular weight poly(lactic acid) was verified by gel permeation chromatography. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry showed that the above oligomerization was accompanied by the formation of cyclic compounds. By these means the feasability of a simple transesterification for a controlled synthesis of telechelic oligomers with molecular mass being a function of the added amount of diacrylate has been demonstrated. The glass transition temperatures of the elaborated oligomers varied from -35 to -5 degrees C. Subsequent thermal crosslinking was performed using benzoyl peroxide which enabled the formation of amorphous networks with Tg's close to the body temperature of 40 degrees C. Upon storage in a humid atmosphere the initially fairly hard and brittle networks became, due to hydrolysis, progressively more flexible thus demonstrating the potential biodegradability of these materials.

Journal Article↗
PubMed1987

Salmonella decontamination of broiler carcasses with lactic acid, L-cysteine, and hydrogen peroxide.

Experiments on salmonella decontamination of broiler carcasses with lactic acid, L-cysteine, and hydrogen peroxide were performed. Treatment with lactic acid (1%) and hydrogen peroxide (.5%) resulted in a 4-log cycle reduction in colony forming units of Salmonella typhimurium both with pure cultures and with artificially inoculated broiler carcasses. L-cysteine was nonbactericidal in these experiments.

Animals↗
PubMed2005

Selection of medium components by Plackett-Burman design for production of L(+) lactic acid by Lactobacillus amylophilus GV6 in SSF using wheat bran.

Plackett-Burman design was employed for screening 15 parameters for production of L(+) lactic acid from wheat bran, an inexpensive substrate and solid support, by Lactobacillus amylophilus GV6 in solid state fermentation (SSF). Eleven nutrients belonging to two categories viz.; nitrogen sources and salt sources along with three physical parameters and a buffer were screened. This design screens n variables in n + 1 number of experiments. Coefficients and sum of squares ratio in percentage (SS%) of these variables were calculated by subjecting the experimental data to statistical analysis. The nitrogen sources peptone, yeast extract and tri-ammonium citrate, along with NaH2PO4.2H2O and Tween 80, were found to influence productivity, which can be further optimized for increased lactic acid production. Use of this design is scarce in solid state fermentation and has not been attempted previously for single step conversion of starch to L(+) lactic acid using a bacterial system.

Algorithms↗
PubMed2001

Comparison of pattern recognition techniques for the identification of lactic acid bacteria.

AIMS: The goal of this study was to evaluate three pattern recognition methods for use in the identification of lactic acid bacteria. METHODS AND RESULTS: Lactic acid bacteria (21 unknown isolates and 30 well-characterized strains), including the Lactobacillus, Lactococcus, Streptococcus, Pediococcus and Oenococcus genera, were tested for 49 phenotypic responses (acid production on carbon sources). The results were scored in several ways. Three procedures, k-nearest neighbour analysis (KNN), k-means clustering and fuzzy c-means clustering (FCM), were applied to the data. CONCLUSION: k-Nearest neighbour analysis performed better with five-point-scaled than with binary data, indicating that intermediate values are helpful to classification. k-Means clustering performed slightly better than KNN and was best with fuzzified data. The best overall results were obtained with FCM. Genus level classification was best with FCM using an exponent of 1.25. SIGNIFICANCE AND IMPACT OF THE STUDY: The three pattern recognition methods offer some advantages over other approaches to organism classification.

Bacterial Typing Techniques↗
PubMed2001

Recombinant Escherichia coli engineered for production of L-lactic acid from hexose and pentose sugars.

Recombinant Escherichia coli have been constructed for the conversion of glucose as well as pentose sugars into L-lactic acid. The strains carry the lactate dehydrogenase gene from Streptococcus bovis on a low copy number plasmid for production of L-lactate. Three E. coli strains were transformed with the plasmid for producing L-lactic acid. Strains FBR9 and FBR11 were serially transferred 10 times in anaerobic cultures in sugar-limited medium containing glucose or xylose without selective antibiotic. An average of 96% of both FBR9 and FBR11 cells maintained pVALDH1 in anaerobic cultures. The fermentation performances of FBR9, FBR10, and FBR11 were compared in pH-controlled batch fermentations with medium containing 10% w/v glucose. Fermentation results were superior for FBR11, an E. coli B strain, compared to those observed for FBR9 or FBR10. FBR11 exhausted the glucose within 30 h, and the maximum lactic acid concentration (7.32% w/v) was 93% of the theoretical maximum. The other side-products detected were cell mass and succinic acid (0.5 g/l).

Culture Media↗
PubMed2004

Characterization of neural stem cells on electrospun poly(L-lactic acid) nanofibrous scaffold.

Nanofibrous poly(L-lactic acid) (PLLA) scaffolds were fabricated by an electrospinning technique and characterized by scanning electron microscopy, mercury porosimeter, atomic force microscopy and contact-angle test. The produced PLLA fibers with diameters ranging from 150 to 350 nm were randomly orientated with interconnected pores varying from several microm to about 140 microm in-between to form a three-dimensional architecture, which resembles the natural extracellular matrix structure in human body. The in vitro cell culture study was performed and the results indicate that the nanofibrous scaffold not only supports neural stem cell (NSC) differentiation and neurites out-growth, but also promotes NSC adhesion. The favorable interaction between the NSCs and the nanofibrous scaffold may be due to the greatly improved surface roughness of the electrospun nanofibrous scaffold. As evidenced by this study, the electrospun nanofibrous scaffold is expected to play a significant role in neural tissue engineering.

Animals↗
PubMed1985

Lactic acid as a decontaminant in slaughter and processing procedures.

An attempt was made to interrelate the data obtained in experiments conducted by our Department along beef, veal and pig slaughter lines, using lactic acid (LA) for the decontamination of carcasses, cold and hot boned primal cuts, slaughter byproducts, and butcher's knives. First and foremost it was observed, that provided Good Manufacturing Practices are strictly followed, the microbial load of carcass surfaces will be substantially reduced. LA-decontamination may result in an additional reduction. Since in the early post-mortem period bacteria are not yet attached to the meat surface, LA-decontamination should preferably be applied to the hot carcass. It was demonstrated that, dependent on mode and duration of application, LA sprays not exceeding 1% v/v (beef), 1.25% v/v (veal) and 1.5% v/v (pork) resulted in acceptable carcass colour scores. Blood spots, which are particularly prone to discolouration by lactic acid application, should be removed at an early post-mortem stage e.g. by strong showering. The difference in surface pH between LA-treated and control carcasses disappeared within 72 hours post-mortem. Veal longissimus chops treated with LA solutions up to 2% v/v were not identified by a consumer taste panel as significantly different from controls. The 'immediate' bactericidal effect of LA-decontamination for beef, veal and pig carcasses, as well as for pig liver and veal brain, amounted to approximately 1.5 log cycles for the aerobic colony counts, strongly dependent on substrate and conditions of decontamination. In addition, a 'delayed' bacteriostatic effect was observed during storage, which is probably the result of a prolonged lag phase of acid-injured micro-organisms surviving lactic acid decontamination.(ABSTRACT TRUNCATED AT 250 WORDS)

Disinfection↗