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PubMed2003

Optimization and scale-up of L-lactic acid fermentation by mutant strain Rhizopus sp. MK-96-1196 in airlift bioreactors.

We determined the optimum culture conditions such as inoculum size, initial starch concentration, pH during the fermentation and aeration rate for L-lactic acid production by Rhizopus sp. MK-96-1196 in a 3-l airlift bioreactor. More than 90 g/l of L-lactic acid was produced from only partially enzymatically hydrolyzed corn starch with a production rate of 2.6 g/l/h and a product yield of 87% based on the starch consumed under the optimum conditions in the 3-l airlift bioreactor. Scale-up from the 3-l to a 100-l airlift bioreactor for L-lactic acid fermentation was carried out using V(s)(cm/s) as a scale-up criterion. The production rates and yields of L-lactic acid in both bioreactors appeared to be fairly well correlated with k(L)a (1/h).

Journal Article↗
PubMed1983

Blood osmolality in vitro: dependence on PCO2, lactic acid concentration, and O2 saturation.

Changes of osmolality (Osm) were measured by freezing-point determination in true plasma of 10 healthy subjects. This was done after equilibration with CO2 (0.5-10.0%), after the addition of lactic acid (10 and 20 mmol/l), and after deoxygenation. The graph for the dependence of Osm on CO2 partial pressure (PCO2) in oxygenated blood resembles the classical CO2 absorption curve. The increase of Osm with PCO2 (approximately 0.2 mosmol . kg H2O-1 . Torr-1) is almost as great as the increase in dissolved CO2 plus bicarbonate (HCO-3). Addition of lactic acid shifts the curve upward by only 0.6 mosmol/mmol because of displacement of HCO-3. Deoxygenation has no significant effect at constant PCO2 despite an increase in [HCO-3]. This is probably due to the binding of 2,3-diphosphoglycerate to hemoglobin. It can be seen in the Osm-pH diagram that differences between CO2 and lactic acid titration largely disappear. For each lactic acid concentration there is a linear dependence corresponding to the linear [HCO-3]-pH relation in plasma. At constant pH, Osm increases after deoxygenation. The observed in vitro relation might explain part of the osmolality increase during physical exercise.

Adult↗
PubMed1993

Influences on the gamma-muscle spindle system from muscle afferents stimulated by KCl and lactic acid.

It is known that accumulation of contraction metabolites in muscles stimulates group III and IV afferents and induces excitation of gamma-efferents to the homonymous muscle. The aim of the present study was to investigate whether increased concentrations of lactic acid and KCl in one muscle may influence the activity in primary and secondary muscle spindle afferents (MSAs) from the chemically affected muscle and from surrounding muscles. The experiments were made on 7 cats anesthetized with alpha-chloralose. Recordings were made simultaneously from 2-8 single MSAs from the triceps surae (GS) and the posterior biceps and semitendinosus muscles (PBSt). The mean rate of firing and the depth of modulation of MSA responses to sinusoidal stretching of the receptor-bearing muscles were determined. Responses of 27 primary MSAs (11 from PBSt and 16 from GS) were recorded. On 24 of these clear-cut alterations in sinusoidal response were evoked by injection of 1 ml of KCl (50-600 mM) or 1 ml of lactic acid (20-200 mM) into the artery supply of the GS muscle. Also, all secondary MSAs recorded (4 from PBSt and 1 from GS) showed sizable effects to increased intramuscular concentrations of KCl and/or lactic acid. On both primary and secondary MSAs, from GS as well as from PBSt muscles, nearly all effects observed were compatible with activation of static fusimotor neurons. Effects on MSAs were completely abolished when the ipsilateral L7-L6 ventral roots were cut and when the GS nerve was anesthetized. Intravenous injections of KCl and lactic acid, as well as arterial injections of 0.9% NaCl, were ineffective in changing the MSA responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Local↗
PubMed2005

Reduction of fumonisin B1 and zearalenone by lactic acid bacteria in fermented maize meal.

Fusarium species are fungi that infect maize products worldwide and elaborate mycotoxins, which have been associated with cancer. This study was carried out to investigate the potential of lactic acid bacteria fermentation in reducing mycotoxin concentration and toxicity in maize meal products. Maize meal was spiked separately with fumonisin B1 and zearalenone and then allowed to ferment for 4 days. The potential cytotoxicity of the mycotoxin-spiked fermented extracts was also investigated using the SNO human esophageal carcinoma cell line (the SNO cell line was explanted from a cancer patient, S.N., a 62-year-old Zulu man, in July 1972). A significant decrease (P < 0.05) in the concentration of the two mycotoxins was observed, with a 56 to 67% and a 68 to 75% reduction in the third and fourth days, respectively. The two mycotoxins were not detectable in commercially fermented maize meal (amahewu) samples. After fermentation, mycotoxin-spiked maize meal samples containing lactic acid bacteria culture were comparatively less toxic to SNO cells than were samples without lactic acid bacteria. However, this difference in toxicity was not significant (P > 0.05). These results indicate that lactic acid bacteria fermentation can significantly reduce the concentration of mycotoxins in maize. However, such a reduction may not significantly alter the possible toxic effects of such toxins. The exact mechanism of toxin reduction warrants further investigation.

Consumer Product Safety↗
PubMed1999

Simultaneous saccharification and extractive fermentation of lignocellulosic materials into lactic acid in a two-zone fermentor-extractor system.

Simultaneous saccharification and extractive fermentation of lignocellulosic materials into lactic acid was investigated using a two-zone bioreactor. The system is composed of an immobilized cell reactor, a separate column reactor containing the lignocellulosic substrate and a hollow-fiber membrane. It is operated by recirculating the cell free enzyme (cellulase) solution from the immobilized cell reactor to the column reactor through the membrane. The enzyme and microbial reactions thus occur at separate locations, yet simultaneously. This design provides flexibility in reactor operation as it allows easy separation of the solid substrate from the microorganism, in situ removal of the product and, if desired, different temperatures in the two reactor sections. This reactor system was tested using pretreated switchgrass as the substrate. It was operated under a fed-batch mode with continuous removal of lactic acid by solvent extraction. The overall lactic acid yield obtainable from this bioreactor system is 77% of the theoretical.

Journal Article↗
PubMed2006

Simultaneous saccharification and fermentation of cassava bagasse for L-(+)-lactic Acid production using Lactobacilli.

Saccharification and fermentation of cassava (Manihot esculenta) bagasse was carried out in a single step for the production of L-(+)-lactic acid by Lactobacillus casei and Lactobacillus delbrueckii. Using 15.5% w/v of cassava bagasse as the raw material, a maximum starch to lactic acid conversion of 96% was obtained with L. casei with a productivity rate of 1.40 mg/mLxh and maximum yield of 83.8 mg/mL. It was 94% with L. delbrueckii with a productivity rate of 1.36 mg/mLxh and maximum yield of 81.9 mg/mL. Supplementation of bagasse with 0.01% w/v MnCl2 showed positive influence on the lactic acid production by L. casei.

Bioreactors↗
PubMed1990

Dissolution mechanism of zinc phosphate dental cement in acetic and lactic acid buffers.

When zinc phosphate cement was immersed in 0.1 M acetic and lactic acid buffer solutions adjusted to pH 4.1, its dissolution rate was determined by chemical analysis. The eroded surface of the cement was examined by X-ray diffraction and SEM observation. The dissolution process of the cement immersed in the acetic acid buffer solution was mainly controlled by the diffusion of releasing species through the cement matrix and that of the cement immersed in the lactic acid buffer solution by the decomposition of the cement matrix at the surface.

Acetates↗
PubMed2006

L-lactic acid production by Lactobacillus casei fermentation with corn steep liquor-supplemented acid-hydrolysate of soybean meal.

Batch and fed-batch fermentation studies were performed to evaluate the potential of corn steep liquor (CSL)-supplemented acid-hydrolysate of soybean meal (AHSM) as an alternative to yeast extract (YE) for the production of L-lactic acid by Lactobacillus casei LA-04-1. The CSL-supplemented AHSM gave an outstanding result in supporting L-lactic acid production from glucose. In the exponential fed-batch fermentation, the concentration, yield and productivity of L-lactic acid were 162.5 g/L, 89.7% and 1.69 g/L per h, respectively, which were lower than those with 20 g/L YE (180 g/L, 90.3%, 2.14 g/L per h) after 96 h of fermentation. However, the raw material cost of the nitrogen resource was estimated as only 25% of that using the YE.

Acids↗
PubMed2006

Usefulness of length heterogeneity-PCR for monitoring lactic acid bacteria succession during maize ensiling.

The use of length-heterogeneity PCR was explored to monitor lactic acid bacteria succession during ensiling of maize. Bacterial diversity was studied during the fermentation of 30-day-old maize in optimal and spoilage-simulating conditions. A length heterogeneity PCR profile database of lactic acid bacteria isolated from the silage and identified by 16S rRNA gene sequencing was established. Although interoperonic 16S rRNA gene length polymorphisms were detected in some isolates, strain analysis showed that most of the lactic acid bacteria species thriving in silage could be discriminated by this method. The length heterogeneity PCR profiles of bacterial communities during maize fermentation were compared with those on a database. Under optimal fermentation conditions all the ecological indices of bacterial diversity, richness and evenness, deduced from community profiles, increased until day thirteen of fermentation and then decreased to the initial values. Pediococcus and Weissella dominated, especially in the first days of fermentation. Lactococcus lactis ssp. lactis and Lactobacillus brevis were mainly found after six days of fermentation. A peak corresponding to Lactobacillus plantarum was present in all the fermentation phases, but was only a minor fraction of the population. Unsuitable fermentation conditions and withered maize leaves in the presence of oxygen and water excess caused an enrichment of Enterococcus sp. and Enterobacter sp.

Base Sequence↗
PubMed2002

Lactic acid bacteria isolated from soy sauce mash in Thailand.

Fourteen sphere-shaped and 30 rod-shaped lactic acid bacteria were isolated from soy sauce mash of two factories in Thailand. These strains were separated into two groups, Group A and Group B, by cell shape and DNA-DNA similarity. Group A contained 14 tetrad-forming strains, and these strains were identified as Tetragenococcus halophilus by DNA similarity. Group B contained 30 rod-shaped bacteria, and they were further divided into four Subgroups, B1, B2, B3, and B4, and three ungrouped strains by phenotypic characteristics and DNA similarity. Subgroup B1 contained 16 strains, and these strains were identified as Lactobacillus acidipiscis by DNA similarity. Subgroup B2 included two strains, and the strains were identified as Lactobacillus farciminis by DNA similarity. Subgroup B3 contained five strains. The strains had meso-diaminopimelic acid in the cell wall, and were identified as Lactobacillus pentosus by DNA similarity. The strains tested produced DL-lactic acid from D-glucose. Subgroup B4 contained four strains. The strains had meso-diaminopimelic acid in the cell wall, and they were identified as Lactobacillus plantarum by DNA similarity. Two ungrouped strains were homofermentative, and one was heterofermentative. They showed a low degree of DNA similarity with the type strains tested, and were left unnamed. The distribution of lactic acid bacteria in soy sauce mash in Thailand is discussed.

Cell Wall↗
PubMed1993

Identification of a novel operon in Lactococcus lactis encoding three enzymes for lactic acid synthesis: phosphofructokinase, pyruvate kinase, and lactate dehydrogenase.

The discovery of a novel multicistronic operon that encodes phosphofructokinase, pyruvate kinase, and lactate dehydrogenase in the lactic acid bacterium Lactococcus lactis is reported. The three genes in the operon, designated pfk, pyk, and ldh, contain 340, 502, and 325 codons, respectively. The intergenic distances are 87 bp between pfk and pyk and 117 bp between pyk and ldh. Plasmids containing pfk and pyk conferred phosphofructokinase and pyruvate kinase activity, respectively, on their host. The identity of ldh was established previously by the same approach (R. M. Llanos, A. J. Hillier, and B. E. Davidson, J. Bacteriol. 174:6956-6964, 1992). Each of the genes is preceded by a potential ribosome binding site. The operon is expressed in a 4.1-kb transcript. The 5' end of the transcript was determined to be a G nucleotide positioned 81 bp upstream from the pfk start codon. The pattern of codon usage within the operon is highly biased, with 11 unused amino acid codons. This degree of bias suggests that the operon is highly expressed. The three proteins encoded on the operon are key enzymes in the Embden-Meyerhoff pathway, the central pathway of energy production and lactic acid synthesis in L. lactis. For this reason, we have called the operon the las (lactic acid synthesis) operon.

Amino Acid Sequence↗
PubMed2001

Dysfunctional mitochondria, not oxygen insufficiency, cause cancer cells to produce inordinate amounts of lactic acid: the impact of this on the treatment of cancer.

It has been known for decades that cancer cells produce excessive amounts of lactic acid. The fact that most cancers have poor vascular systems has led cancer scientists to assume that such cells are deprived of a normal supply of oxygen. Researchers believe that without sufficient oxygen, cancer cells must revert to fermentation for their energy supply and this is what causes them to produce excessive lactic acid. I challenge this traditional assumption and suggest instead that cancer cells have dysfunctional mitochondria, which prevent their use of the citric acid or Krebs cycle. Consequently, pyruvic acid, the end product of glycolysis, which normally would enter the mitochondria for its total combustion into energy, is instead converted to lactic acid. Evidence exists to support this hypothesis which, when acknowledged, could dynamically impact both cancer research and the treatment of all forms of cancer.

Humans↗
PubMed1987

In vitro lactic acid inhibition and alterations in volatile fatty acid production by antimicrobial feed additives.

Batch culture fermentations were used to determine the effects of avoparcin, lasalocid, monensin, narasin, salinomycin, thiopeptin, tylosin, virginiamycin, monensin + tylosin combination, and two new ionophore compounds (RO22-6924/004 and RO21-6447/009) on lactic acid and volatile fatty acid (VFA) production. Ruminal fluid from cattle fed a high alfalfa hay diet was incubated with glucose for 12 h in a buffered medium to determine the effect of antimicrobial compounds on lactic acid concentration. Fermentations treated with antimicrobial compounds had higher final pH and lower L(+) lactic acid concentration. Narasin and salinomycin were more inhibitory than other ionophore compounds. Monensin and tylosin in combination was more effective than monensin alone. Among the nonionophore compounds, avoparcin was the least effective and thiopeptin, tylosin and virginiamycin were extremely effective in reducing lactic acid concentration. Ruminal fluid from cattle fed a diet of alfalfa hay and grain (50:50) was incubated with a mixture of sugars, casein and urea for 12 h in a buffered medium to determine the effect of antimicrobial compounds on VFA production. Generally, total VFA concentration was not affected by antimicrobial compounds except RO22-6924/004, tylosin and virginiamycin, which caused a reduction at high concentrations. Tylosin, monensin and tylosin mixture, thiopeptin and virginiamycin at high concentrations (greater than 6.0 micrograms/ml) increased the acetate proportion. All compounds increased the molar proportion of propionate. Tylosin and virginiamycin at high concentrations (greater than 6.0 micrograms/ml) decreased the proportion of propionate. Monensin and tylosin in combination had no effect on propionate proportion. Among the compounds tested, narasin and salinomycin were the most effective in enhancing propionate proportion. Ionophore compounds were more inhibitory to butyrate production than the nonionophore compounds. Batch culture fermentations may be used to quantitate the relative efficacy of antimicrobial compounds to alter ruminal fermentation characteristics.

Animals↗
PubMed2005

Differential real-time PCR assay for enumeration of lactic acid bacteria in wine.

Oenococcus oeni is often employed to perform the malolactic fermentation in wine production, while nonoenococcal lactic acid bacteria often contribute to wine spoilage. Two real-time PCR assays were developed to enumerate the total, and nonoenococcal, lactic acid bacterial populations in wine. Used together, these assays can assess the spoilage risk of juice or wine from lactic acid bacteria.

Lactobacillus↗
PubMed1998

Amine-based aqueous polymers for the simultaneous titration and extraction of lactic acid in aqueous two-phase systems.

The partitioning of 10% (w/w) lactic acid in ethylene oxide propylene oxide (EOPO) random copolymers and dextran T500 aqueous two-phase systems was studied. An analysis of variance design was applied to investigate the effect of pH, polymer concentration, and addition of polyethyleneimine to the aqueous two-phase systems. The lowest lactate partition coefficient of 0.09 was obtained at pH 6 in the systems containing 7.2% (w/w) polyethyleneimine. The use of polyethyleneimine as titrating base during the fermentative production of lactic acid was evaluated in batch fermentations with 100 g/l glucose. Yield and productivity of polyethyleneimine titrated fermentations compared with those obtained in fermentations titrated with NaOH and KOH.

Chemistry Techniques, Analytical↗
PubMed1993

Capsazepine-sensitive release of calcitonin gene-related peptide from C-fibre afferents in the guinea-pig heart by low pH and lactic acid.

The present study aimed to evaluate the possible influence of the selective capsaicin antagonist, capsazepine, on the release of calcitonin gene-related peptide (CGRP)-like immunoreactivity from sensory nerves in the isolated perfused guinea-pig heart. Low-pH buffer (pH 7, 6, 5), capsaicin (10(-7) M), lactic acid (5, 20, 50 mM) and nicotine (10(-4) M) all evoked a clear-cut release of CGRP-like immunoreactivity. Incubation with capsazepine (10(-6) to 10(-5) M) significantly reduced the CGRP-like immunoreactivity release evoked by low pH, capsaicin and lactic acid (5 mM) but not that evoked by nicotine. Furthermore, the capsaicin-evoked stimulation of heart rate was inhibited by incubation with capsazepine. The inorganic dye, ruthenium red, which has previously been shown to attenuate capsaicin-, but not nicotine-induced CGRP release from the heart, also reduced the release of CGRP caused by low pH and lactic acid (5 mM). It is concluded that the CGRP-like immunoreactivity release evoked from the heart by low pH and lactic acid shares several characteristic features with the release evoked by capsaicin. Since tissue pH is low in myocardial ischaemia and this is well known to cause pain, the use of capsazepine to inhibit the function of C-fibre afferents may represent a novel principle to influence autonomic reflex reactions associated with cardiac pathological conditions.

Animals↗
PubMed2001

[Lactic acid polymer implants in the repair of traumatic defects of the orbital floor].

BACKGROUND: The criteria determining the choice of the technique used to repair traumatic orbital floor defects include the quality of the expected result, morbidity, ease of use and plasticity of the method, and its cost and availability. Among the different methods proposed, lactic acid polymer implants are particularly interesting. MATERIAL AND METHODS: Eighteen patients with an isolated blow-out fracture of the orbital floor were treated with a lactic acid polymer implant between 1995 and 1996. Ten of these patients were reviewed at 24 to 43 months follow-up. RESULTS: The mean age of the patients was 35 years (20-52 years). No residual diplopia was observed. None of the patients had an anomalous orbital volume or ocular dystopia. None of the implants migrated. One patient experienced episodes of palpebral inflammation that resolved spontaneously. The ten patients reviewed were satisfied with the outcome. DISCUSSION: The properties of lactic acid polymer implants facilitate their use, avoid morbidity and provide a quality result. This is the procedure of choice for repairing tissue loss of the orbital floor. It has several advantages over alternative methods (the implants are rigid, thin, resorbable and well tolerated) without having their defects (thickness, fragility, roughness, predetermined form, rapid alteration, specific instrumentation, iatrogenic disorders). In addition, lactic acid polymer plates can be remodeled when heated, allowing a precise adaptation of the implant to the orbital structures. Finally, the cost, compared with the advantages, is not a barrier for routine use.

Absorbable Implants↗