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PubMed1997

[Fermentation process during the ensiling of green forage low in nitrate. 2. Fermentation process after supplementation of nitrate, nitrite, lactic acid bacteria and formic acid].

The effect of adding nitrate and nitrite (0.05% and 0.01% N in DM) of two inoculants or formic acid on the ensiling of orchardgrass and a grass-legumes-mixture, both low in nitrate, was proved in two experiments during ensiling starting in an early stage of fermentation silages without additives contained butyric acid, with increasing amounts up to 180 day of storage period. Silages with added nitrate or nitrite (0.1% N in DM) contained no butyric acid despite of a delay in the formation of lactic acid Nitrite was more effective as nitrate (both 0.05% N in DM) to suppress butyric acid fermentation. However, both additives, nitrite and nitrate, increased the lactic acid fermentation. Interpreting this facts it was hypothesized that the clostridia was inhibited by nitrate and nitrite. Addition of inoculants improved the formation of lactic acid, and decreased pH-value in comparison to control silages. The formation of butyric acid was limited, but not suppressed. The effect of inoculants differed in the intensity of fermentation and the formation of by-products of lactic acid fermentation. The effect of formic acid was not sure.

Animal Nutritional Physiological Phenomena↗
PubMed1995

Synovial fluid L-lactic acid in acute arthritis of the adult knee joint.

Determination of synovial fluid (SF) lactic acid has been suggested to be an unspecific indicator of SF leukocytosis, and it is not recommended for differential diagnosis of bacterial arthritis. We analyzed the L-lactic acid content by enzymatic UV-method in 65 SF samples obtained from adult patients with acute knee arthritides. The concentration of L-lactic acid was not high in any SFs with intensive leukocytosis. The mean concentration of L-lactic acid was 13.5 mmol/l (95% confidence intervals 9.4; 17.6 mmol/l) in the synovial-fluid samples from culture-positive arthritis and 5.5 mmol/l (4.9; 6.2 mmol/l) in the synovial-fluid samples from culture-negative arthritis. Determination of SF L-lactic acid is an important part of the diagnostic setup for acute arthritis. Values > 9 mmol/l strongly support occurrence of bacterial arthritis and indicates an immediate onset of the treatment.

Acute Disease↗
PubMed2000

Molecular biology of oxygen tolerance in lactic acid bacteria: Functions of NADH oxidases and Dpr in oxidative stress.

Lactic acid bacteria including Streptococcus mutans lack cytochromes and heme-containing proteins. Most lactic acid bacteria also lack catalase. However, they can grow in the presence of air. In view of the defense against oxygen toxicity, the lack of catalase in lactic acid bacteria is not always consistent with its aerotolerance. Mechanisms, by which lactic acid bacteria establish their growth in air, are therefore an active area of investigation. We identified two kinds of NADH oxidase genes, nox-1 and nox-2 for H2O2-forming NADH oxidase (Nox-1) and H2O-forming NADH oxidase (Nox-2), respectively, in S. mutans and found that Nox-1 is homologous with flavoprotein component, AhpF, of Salmonella typhimurium alkyl hydroperoxide reductase (AhpR), consisting of AhpF and AhpC. We also identified ahpC which is homologous with ahpC of S. typhimurium, upstream of nox-1 in S. mutans. In the first and second parts of this article, we will refer to the role of Nox-1 which acts together with AhpC as bi-component peroxidase system in S. mutans, catalyzing the NADH-dependent reduction of organic hydroperoxides or H2O2 to their respective alcohol and/or H2O. We will also refer to the role of Nox-2 in carbohydrate metabolism of S. mutans in its aerobic life. Nox-2 was found to be involved in regenerating NAD+, which is required for glycolysis in S. mutans. While studying nox-1 and ahpC double deletion mutant of S. mutans, we found that the mutant still showed the same level peroxide tolerance as did the wild-type strain. The finding suggested the existence of another antioxidant system in addition of Nox-1 and AhpC in S. mutans. We identified a new gene, dpr (for Dps-like Peroxide Resistance gene) and its product, Dpr, as an iron-binding protein which is responsible for oxygen tolerance in S. mutans. In the third part of this article, we will refer to the current status of knowledge of molecular cloning of dpr, the characteristics of dpr-disruption mutants, and a mechanism by which Dpr confers aerotolerance to S. mutans.

Journal Article↗
PubMed2005

Production of D-lactic acid from defatted rice bran by simultaneous saccharification and fermentation.

Production of d-lactic acid from rice bran, one of the most abundant agricultural by-products in Japan, is studied. Lactobacillus delbrueckii subsp. delbrueckii IFO 3202 and defatted rice bran powder after squeezing rice oil were used for the production. Since the rice bran contains polysaccharides as starch and cellulose, we coupled saccharification with amylase and cellulase to lactic acid fermentation. The indigenous bacteria in the rice bran produced racemic lactic acid in the saccharification at pH 6.0-6.8. Thus the pH was controlled at 5.0 to suppress the growth of the indigenous bacteria. L. delbrueckii IFO 3202 produced 28 kgm(-3) lactic acid from 100 kgm(-3) rice bran after 36 h at 37 degrees C. The yield based on the amount of sugars soluble after 36-h hydrolysis of the bran by amylase and cellulase (36 kgm(-3) from 100 kgm(-3) of the bran) was 78%. The optical purity of produced d-lactic acid was 95% e.e.

Carbohydrate Metabolism↗
PubMed2005

Simultaneous determination of l- and d-lactic acid in plasma by capillary electrophoresis.

A novel method for simultaneous determination of d- and l-lactic acids in plasma was presented by capillary electrophoresis with photodiode array detection at 195nm. The separation was performed in an uncoated fused-silica capillary. The parameters influencing the resolution and the migration time of lactic acids were optimized. When 150mM phosphate-Tris buffer (pH 7.0) consisting of 220mM 2-hydroxypropyl-beta-cyclodextrin and 0.2mM tetradecyltrimethylammonium bromide was utilized as the running buffer, highly effective chiral separation of d- and l-lactic acids was achieved at about 42min at an effective voltage of -25kV. The resolution of lactic acid enantiomers was >/=1.25. The limits of detection of d- and l-lactic acids in standard solution without any pretreatment were 80 and 50muM (S/N=3), respectively. Sample pretreatment was preceded by protein-removal procedure with acetonitrile. With a pre-concentration procedure by 10 times, the limits of detection of d- and l-lactic acids were 20 and 15muM (S/N=10), respectively. The satisfactory analytical performance of the proposed method was validated.

Animals↗
PubMedDate not supplied

Effect of hypoglycemia on changes of brain lactic acid and intracellular pH produced by ischemia.

Previous investigators have attributed the fall of brain intracellular pH (pHi) produced by ischemia to accumulation of lactic acid. The goal of the present experiments was to examine the hypothesis that the acidosis produced by cerebral ischemia is due to accumulation of lactic acid. The present experiments inhibited lactic acid production by lowering glucose availability using insulin-induced hypoglycemia. The adverse effects of hypoglycemia were prevented by the prior elevation of beta-hydroxybutyric acid and acetoacetic acid induced by a high lipid diet. Brain pHi and lactic acid were measured by 31P and 1H NMR. The results showed that insulin-induced hypoglycemia markedly inhibits production of lactic acid, but has no effect on brain pHi during ischemia. These findings suggest that, at least under some conditions, the acidosis produced by cerebral ischemia is not due to accumulation of lactic acid.

Adenosine Triphosphate↗
PubMed2006

Racemization of l-lactic acid in pH-swing open fermentation of kitchen refuse by selective proliferation of Lactobacillus plantarum.

We have shown that stable lactic acid fermentation of model kitchen refuse occurs with intermittent pH adjustment under nonsterilized conditions. Nonetheless, the optical activity of the accumulated lactic acid was low, which is disadvantageous for the production of high-quality poly-l-lactic acid. Here, we attempt to increase optical purity by introducing l-lactic acid-producing strains under nonsterilized conditions and demonstrate that the inoculation of Lactobacillus rhamnosus or Lactococcus lactis, both of which are l-lactic acid producers, is partially effective in the early fermentation stage, but does not improve the final optical purity of the accumulated lactic acid. We confirmed by fluorescence in situ hybridization using group-specific and species-specific 16S rDNA probes that this is due to the selective proliferation of naturally existing L. plantarum. L. plantarum KY-1, which is isolated from model kitchen refuse, showing lactic acid racemase activity, as well as d-lactate dehydrogenase activity, in its membrane fraction. We conclude that racemase activity associated with L. plantarum is the main cause of decreased optical purity in the accumulated lactic acid.

Fermentation↗
PubMedDate not supplied

Optimization of in vitro skin permeation by lactic acid from gel formulations.

The purpose of this study was to evaluate the effect of the concentration as well as the vehicle's pH on in vitro skin permeation by lactic acid from gel formulations, using an optimization technique. Nine gels containing 3%, 6%, and 9% (w/w) lactic acid in three different phosphate buffers, with pH values of 2.8, 3.8, and 4.8, were prepared and were applied in modified Franz diffusion cells. The pH of the vehicles and the lactic acid concentrations were used to create a mathematical model that correlates these factors with the cumulative amount of lactic acid permeated through human cadaver epidermis. For this purpose, the optimization technique 3(2) was applied. It was found that the correlation of the above factors can be adequately described with a polynomial equation, which can be used for predicting the cumulative amounts of lactic acid permeated. The results indicated that as the lactic acid's concentration increased, the cumulative amount permeated also increased after 24 h at all pH values. Moreover, the amount of lactic acid permeated decreased as the pH of the gels was increased. The greater amount permeated at all time intervals (6 h, 9 h, 12 h, and 24 h) was obtained when the concentration of lactic acid was 9% and the pH of the gel formulation was 2.8.

Chromatography, High Pressure Liquid↗
PubMed1983

Lactic acid fermentation in the production of foods from vegetables, cereals and legumes.

Lactic acid bacteria perform an essential role in the preservation and production of wholesome foods. Generally the lactic acid fermentations are low-cost and often little or no heat is required in their preparation. Thus, they are fuel-efficient. Lactic acid fermented foods have an important role in feeding the world's population on every continent today. As world population rises, lactic acid fermentation is expected to become even more important in preserving fresh vegetables, fruits, cereals and legumes for feeding humanity.

Dairy Products↗
PubMed1989

Loss of forestomach motility in sheep experiencing ruminal lactic acidosis is not dependent on duodenal acidification by lactic acid.

Reticuloruminal motility, duodenal myoelectrical activity, and the pH and lactic acid concentrations of ruminal and duodenal contents were monitored in rumen fistulated sheep that were intraruminally loaded with finely ground wheat (50 g/kg). Following ruminal loading, reticuloruminal motility was enhanced. However, within 6 hours of loading, forestomach motility was impaired and within 9 hours ruminal stasis occurred. During loss of forestomach motility, lactic acid concentrations in ruminal contents increased and may, in part, have contributed to the decrease in pH of ruminal fluids. The levels of lactic acid within duodenal contents also rose, however, the pH of duodenal contents remained unchanged. During the loss of reticuloruminal motility, premature regular spiking activity (RSA) and/or abnormal patterns of migrating myoelectric complexes (MMC) were not observed on the duodenum. These findings indicate that loss of forestomach motility in ruminal lactic acidosis may not be a consequence of acidification of the proximal duodenum by lactic acid produced in the forestomach.

Acidosis, Lactic↗
PubMed2006

High performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) assay for chiral separation of lactic acid enantiomers in urine using a teicoplanin based stationary phase.

A novel method for the separation and simultaneous determination of urinary D- and L-lactic acid enantiomers by high performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) is presented. The chiral separation was optimized on a Chirobiotic teicoplanin aglyocone (TAG) column. Most interestingly, the addition of water in small volume fraction to the polar organic mobile phase was found to significantly improve the chromatography. Calibration curves were linear (r2>0.9950) over the range 3-1000 mg/L for L-lactic acid and 0.5-160.8 mg/L for D-lactic acid. The limit of detection (LOD) (S/N=3) and limit of quantification (LOQ) (S/N=10) were determined experimentally (n=3) to be 0.2 and 0.5mg/L for L-lactic acid and 0.4 and 1.3 mg/L for D-lactic acid, respectively. The normal patient range of L-lactic acid was 1-20 microg/mg creatinine with an elevated value of 85 microg/mg creatinine. For D-lactic acid, the range of normal values were between 0 and 5 microg/mg creatinine with an elevated value of 40 microg/mg creatinine. Finally, the validated method allows for rapid analysis with a total run time of 7.5 min.

Calibration↗
PubMed2006

The role of monocarboxylate transporters in uptake of lactic acid in HeLa cells.

This study was aimed to identify the monocarboxylate transporters (MCTs) in HeLa cells and to delineate their role in transportation of L-lactic acid. The functional role of MCTs in lactic acid transport was evaluated at various mucosal pHs (4.5-7.4) or in the presence of various loading doses (0.2-2mM) of lactic acid, MCT substrates (nicotinic acid, n-butyric acid, etc.) and inhibitors (alpha-cyano-4-hydroxycinnamate and para-chloromercuribenzoic acid). The molecular properties of MCTs were characterized using reverse transcription-polymerase chain reaction (RT-PCR). The uptake rate of lactic acid by HeLa cells significantly increased from 0.353+/-0.052 to 1.103+/-0.196 micromol/mg protein as the extra-cellular pH changed from 7.4 to 4.5, indicating that activities of MCT were mediated through H(+)-linked mechanism. The uptake profile of lactic acid followed the saturable process with the K(m) value of 0.53 mM. The uptake rate of lactic acid is concentration dependent and is reduced in the presence of MCT inhibitors. MCT isoforms 1, 5 and 6 in HeLa cells were identified by RT-PCR. HeLa cell line can be used as an effective screening tool for intravaginally administered drugs targeted toward MCT.

Biological Transport↗
PubMed2005

The effect of lactic acid on anaerobic carbon or nitrogen limited chemostat cultures of Saccharomyces cerevisiae.

Weak organic acids are well-known metabolic effectors in yeast and other micro-organisms. High concentrations of lactic acid due to infection of lactic acid bacteria often occurs in combination with growth under nutrient-limiting conditions in industrial yeast fermentations. The effects of lactic acid on growth and product formation of Saccharomyces cerevisiae were studied, with cells growing under carbon- or nitrogen-limiting conditions in anaerobic chemostat cultures (D=0.1 h(-1)) at pH values 3.25 and 5. It was shown that lactic acid in industrially relevant concentrations had a rather limited effect on the metabolism of S. cerevisiae. However, there was an effect on the energetic status of the cells, i.e. lactic acid addition provoked a reduction in the adenosine triphosphate (ATP) content of the cells. The decrease in ATP was not accompanied by a significant increase in the adenosine monophosphate levels.

Adenosine Triphosphatases↗
PubMed2000

Levels of lactic acid, normal level & its relation to food, glucose, cholesterol, raised blood urea and phenformin therapy.

1. The level of lactic acid was found to be 25 mg percent in 95 percent of 186 normal Indians. There was no difference due to sex and age. 2. Level of lactic acid was estimated in blood of normal persons and diabetics Type II patients to observe the effects of food and glucose. There was no change except the level of lactic acid was in higher but in normal range. 3. Hyperglycemia of over 300 mg raised the blood lactic acid in 25 percent of patients. 4. Lactic acid was not affected by hypercholesteremia but was raised in 60 percent of cases with raised blood urea. 5. Lactic acid was found to remain within normal limits in 48 type II diabetics treated with phenformin dose varying from 50 mg to 225 mg per day. The duration of treatment varied from one year to seven years.

Diabetes Mellitus, Type 2↗
PubMed1999

Optimization of L-lactic acid production from glucose by Rhizopus oryzae ATCC 52311.

The effect of nutrients on L(+)-lactic acid production from glucose was investigated using Rhizopus oryzae ATCC 52311. From the shake-flask experiments, the optimal medium composition was defined for improved lactic-acid production. In order to enhance lactic-acid production rate and product yield, controlled aeration in a bubble column was conducted under optimal conditions. Results showed a maximum lactic-acid production rate of 2.58 g/L/h was obtained with an initial glucose concentration of 94 g/L. Final lactic-acid concentration of 83 g/L was achieved after 32 h of fermentation with a weight of 0.88 g lactic acid/g glucose consumed.

Journal Article↗
PubMed1992

Rapid and simple gas chromatographic measurement of lactic acid in red blood cells, plasma, and tumor cells after hyperthermia.

The content of lactic acid in red blood cells, plasma, and Ehrlich ascites tumor cells were measured by a gas-liquid chromatography using a column with a terephtalic acid support coated with polyethylene glycol-6000. The lactic acid contents were directly determined in aqueous samples, because they were converted to a volatile derivative in the column. The method was rapid and simple, compared with previous methods which need time-consuming conversion of lactic acid to volatile derivatives. Our measurements showed the increase in the contents of intra- and extracellular lactic acid after hyperthermia.

Animals↗
PubMed1995

D-lactic acid in synovial fluid. A rapid diagnostic test for bacterial synovitis.

OBJECTIVE: To analyze the usefulness of D-lactic acid levels in synovial fluid (SF) as a rapid test to support the early diagnosis of bacterial arthritis (BA). METHODS: A simple modification of the enzyme method used for measuring L-lactic acid was used to analyze levels of D-lactic acid in SF from 20 cases of BA. Results were compared with those from 99 noninfectious arthritis, which included 90 inflammatory SF samples. Total white blood cell count (WBC), percentage of polymorphonuclears (% PMN) and gram stains were also determined. RESULTS: D-lactic acid levels were significantly higher in BA than in noninfectious arthritis. Using a cutoff value of 0.05 mM, 85% of the SF samples from BA had a positive test for D-lactic acid compared with 4% of the control group. The overall sensitivity of the assay was 85% with a specificity of 96%, showing a positive predictive value for BA of 81% and a negative predictive value of 97%. CONCLUSION: The data presented suggest that D-lactic acid is an accurate, easy test that can be carried out in any laboratory, to support the early diagnosis of BA.

Arthritis↗
PubMed2002

Bioabsorbable poly-L-lactic acid cages for lumbar interbody fusion: three-year follow-up radiographic, histologic, and histomorphometric analysis in goats.

STUDY DESIGN: Long-term evaluation was performed for bioabsorbable poly-L-lactic acid cages in a goat interbody fusion model. OBJECTIVE: To assess the radiographic, histologic, and histomorphometric characteristics of poly-L-lactic acid cages during 3 years of follow-up evaluation. SUMMARY OF BACKGROUND DATA: Failed cage fusions may be related to cage design and material in addition to the surgical technique used. To overcome material-related complications and to explore the potential benefits of bioabsorbable cages, poly-L-lactic acid cages have been designed. METHODS: For this study, 36 Dutch milk goats underwent a lumbar interbody fusion procedure (L3-L4). Two types of custom-made cage devices were impacted with bone graft and implanted: poly-L-lactic acid cages (n = 30) and titanium cages (n = 6). Sequential harvesting of surgically managed motion segments (intervals: 3, 6, 12, 24, and 36 months) was performed for analysis. RESULTS: In poly-L-lactic acid specimens, permanent interbody fusion could be achieved within 6 months after surgery with maintenance of cage height. Titanium specimens showed no interbody fusion within this period. Radiographic follow-up evaluation (6-36 months) showed interbody fusion in 86% (19/22) of poly-L-lactic acid specimens, as compared with 33% (2/6) of titanium specimens. After 36 months of implantation, in one half of the specimens, poly-L-lactic acid cages were completely absorbed. Bone histomorphometry showed complete bone remodeling after 2 years of follow-up evaluation. During the study period, no local or distant adverse histologic effects were observed. CONCLUSIONS: The current study showed that poly-L-lactic acid cage devices are feasible for lumbar interbody fusion. New poly-L-lactic acid cages designed for clinical practice might be a viable alternative to current nonabsorbable cage devices.

Absorbable Implants↗