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PubMed1992

Ischemically sensitive visceral afferents: importance of H+ derived from lactic acid and hypercapnia.

Ischemically sensitive abdominal visceral afferents reflexly stimulate the cardiovascular system. To explore the role of H+ contribution by lactic acid and hypercapnia, we recorded single-unit activity of ischemically sensitive abdominal afferents in anesthetized cats. The individual responses to sodium lactate, lactic acid, and hypercapnia then were examined. Abdominal ischemia significantly decreased organ tissue pH from an average of 7.21 +/- 0.03-7.05 +/- 0.03 (P less than 0.05), during which impulse activity of 13 A delta- and 32 C-fibers significantly increased. Although hypercapnia (12% CO2) induced a similar decrease in tissue pH, impulse frequency increased in 0 of 4 A delta- and only 2 of 13 C-fibers. In contrast, lactic acid decreased tissue pH significantly less than ischemia or hypercapnia but increased impulse activity in 7 of 10 A delta- and 11 of 12 C-fibers. Conversely, only 1 of 3 A delta- and 0 of 10 C-fibers responded to sodium lactate. Thus ischemically sensitive visceral afferents respond to the H+ derived from lactic acid rather than hypercapnia. However, these afferents do not respond to sodium lactate. These data suggest that ischemically sensitive abdominal visceral afferents are responsive specifically to lactic acid rather than to the dissociated ions lactate or H+ or to changes in PCO2.

Afferent Pathways↗
PubMed2003

Isolation, characterisation and identification of lactic acid bacteria from bushera: a Ugandan traditional fermented beverage.

One hundred and thirteen strains of lactic acid bacteria (LAB) were selected from 351 isolates from 15 samples of traditionally fermented household bushera from Uganda and also from laboratory-prepared bushera. Isolates were phenotypically characterised by their ability to ferment 49 carbohydrates using API 50 CHL kits and additional biochemical tests. Coliforms, yeasts and LAB were enumerated in bushera. The pH, volatile organic compounds and organic acids were also determined. The LAB counts in household bushera varied between 7.1 and 9.4 log cfu ml(-1). The coliform counts varied between < 1 and 5.2 log cfu ml(-1). The pH of bushera ranged from 3.7 to 4.5. Ethanol (max, 0.27%) was the major volatile organic compound while lactic acid (max, 0.52%) was identified as the dominant organic acid in household bushera. The initial numbers of LAB and coliforms in laboratory-fermented bushera were similar; however, the LAB numbers increased faster during the first 24 h. LAB counts increased from 5.5 to 9.0 log cfu ml(-1) during the laboratory fermentation. Coliform counts increased from 5.9 to 7.8 log cfu ml(-1) at 24 h, but after 48 h, counts were less 4 log cfu ml(-1). Yeasts increased from 4.3 to 7.7 log cfu ml(-1) at 48 h, but thereafter decreased slightly. The pH declined from 7.0 to around 4.0. Lactic acid and ethanol increased from zero to 0.75% and 0.20%, respectively. Lactic acid bacteria isolated from household bushera belonged to Lactobacillus, Streptococcus and Enterococcus genera. Tentatively, Lactobacillus isolates were identified as Lactobacillus plantarum, L. paracasei subsp. paracasei, L. fermentum, L. brevis and L. delbrueckii subsp. delbrueckii. Streptococcus thermophilus strains were also identified in household bushera. LAB isolated from bushera produced in the laboratory belonged to five genera (Lactococcus, Leuconostoc, Lactobacillus, Weissella and Enterococcus. Eight isolates were able to produce acid from starch and were identified as Lactococcus lactis subsp. lactis (four strains), Leuconostoc mesenteroides subsp. mesenteroides (one strain), Leuconostoc mesenteroides subsp. dextranicum (one strain), Weissella confusa (one strain) and L. plantarum (one strain).

Beverages↗
PubMed1985

Lactic acid levels in pleural fluid from patients with bacterial pleuritis.

Pleural fluid lactic acid estimations were carried out on 60 samples by gas-liquid chromatography. Lactic acid levels in 12 patients with bacterial pleural infection were statistically significantly higher (mean, 287 mg/dl; range, 135 to 482 mg/dl) than in 18 patients with malignancy (mean, 71 mg/dl; range, 24 to 157 mg/dl) and 30 other patients with pleural effusions (mean, 19 mg/dl; range, 10 to 57 mg/dl). The determination of pleural fluid lactic acid may help in differentiating between empyema and nonbacterial pleural effusions in most cases. It is of particular value when antibiotic therapy has commenced before specimen collection and may be useful for monitoring therapy.

Bacterial Infections↗
PubMed1979

The role of lactic acid accumulation in muscle fatigue of two species of anurans, Xenopus laevis and Rana pipiens.

Fatigue produced a marked increase in the lactic acid content of hind-limb muscles, the blood, and the whole animal. After 15 min of rest there was little decline of lactic acid levels but the animals could be stimulated into about 3 min of intense activity. This re-fatigue produced a further increase in lactic acid levels. Gastrocnemius muscles removed from fatigued frogs and stimulated in vitro were able to generate initial tensions similar to those in control muscles; total tension was about a third of the control value. In vitro stimulation of these muscles from fatigued frogs led to additional accumulation of lactic acid. Fatigue produced little decrease in the glycogen content of muscles in X. laevis but a marked decrease in R. pipiens. Considerable glycogen stores remained even in the muscles of re-fatigued animals. These data show that accumulation of lactic acid in muscle or blood, depletion of glycogen in muscle, or change in blood pH cannot account for fatigue in these species. Possible other causes of fatigue are discussed.

Animals↗
PubMed2005

Effect of lactic acid and iontophoresis on drug permeation across rabbit ear skin.

The aim of this paper was to explore the efficacy of lactic acid as permeation enhancer for drug molecules across the skin. Three model permeants were chosen: acetaminophen (non-ionized), buspirone hydrochloride (cationic drug) and ibuprofen lysine (anionic drug). We also explored the association of lactic acid and iontophoresis as a means of enhancing drug delivery. Permeation experiments were performed in vitro, using rabbit ear skin as barrier. The results obtained indicate that lactic acid has some effects on model drug permeation across the skin. The effect was more evident with the anionic drug ibuprofen. Cathodal intophoresis increased ibuprofen transport, but when lactic acid was associated with cathodal iontophoresis, a concentration-dependent reduction of ibuprofen iontophoretic flux was observed, probably for the competition by the co-ion. The application of electric current (anodal iontophoresis) to a solution of acetaminophen produced an increase in its transport, due to the presence of an electroosmotic contribution; however, the effect of the association of anodal iontophoresis and lactic acid produced no further enhancement.

Acetaminophen↗
PubMed1994

Capsaicin de-sensitization of the human nasal mucosa reduces pain and vascular effects of lactic acid and hypertonic saline.

The present study was initiated to investigate the effects of hypertonic saline (15%) or low pH (1 M lactic acid, pH 2) applied to the human nasal mucosa. Patients suffering from birch-pollen allergy, which had been de-sensitized with capsaicin, were compared to non-treated, healthy controls. Five patients were pre-treated with an intranasal, unilateral application of 30 microM capsaicin for 15 min during three consecutive days. Six weeks later we applied 50 microliters of hypertonic saline (15%) to the inferior turbinate on the capsaicin-pre-treated side of the patients as well as to the controls. Symptom score, using a visual analogue scale (VAS), and the cross-sectional area of the nasal cavity were measured bilaterally using acoustic rhinometry at different intervals. The same procedure was repeated one week later with lactic acid. Provocation with lactic acid and hypertonic saline caused a significantly higher symptom score in controls as compared to capsaicin-pre-treated patients. Furthermore, application of lactic acid caused a significant reduction in cross-sectional area of the nasal cavity suggesting vasodilatation in controls compared to capsaicin-pre-treated patients. The reactions to hypertonic saline were generally lower but the differences in symptom score between capsaicin-pre-treated and non-treated persons remained. The results implies that capsaicin-sensitive afferents are involved in low pH- and hypertonicity-mediated reactions in the human nasal mucosa. Furthermore, local capsaicin de-sensitization causes a very long-lasting loss of sensory reactivity to these agents.

Adult↗
PubMed2003

Engineering lactic acid bacteria with pyruvate decarboxylase and alcohol dehydrogenase genes for ethanol production from Zymomonas mobilis.

Lactic acid bacteria are candidates for engineered production of ethanol from biomass because they are food-grade microorganisms that can, in many cases, metabolize a variety of sugars and grow under harsh conditions. In an effort to divert fermentation from production of lactic acid to ethanol, plasmids were constructed to express pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH), encoded by the pdc and adhB genes of Zymomonas mobilis, in lactic acid bacteria. Several strains were transformed with the plasmids, and transcription of pdc and adhB was confirmed by northern hybridization analysis of transformants. PDC and ADH enzyme activities were at least 5- to 10-fold lower in these bacteria compared to Escherichia coli transformed with the same plasmid. Glucose fermentations were carried out, and some, but not all, of the transformed strains produced more ethanol than the untransformed parent strains. However, lactic acid was the primary fermentation product formed by all of the transformants, indicating that ADH and PDC activities were insufficient to divert significant carbon flow towards ethanol.

Alcohol Dehydrogenase↗
PubMed2005

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

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.

Ananas↗
PubMed2005

Kinetic analysis of the antibacterial activity of probiotic lactobacilli towards Salmonella enterica serovar Typhimurium reveals a role for lactic acid and other inhibitory compounds.

Six Lactobacillus strains including commercial probiotic ones (L. acidophilus IBB 801, L. amylovorus DCE 471, L. casei Shirota, L. johnsonii La1, L. plantarum ACA-DC 287 and L. rhamnosus GG) were investigated, through batch fermentations under controlled conditions, for their capacity to inhibit Salmonella enterica serovar Typhimurium SL1344. All lactobacilli displayed strong antibacterial activity toward this Gram-negative pathogen and significantly inhibited invasion of the pathogen into cultured human enterocyte-like Caco-2/TC7 cells. By studying the production kinetics of antibacterial activity and applying the appropriate acid and pH control samples during a killing assay, we were able to distinguish between the effect of lactic acid and other inhibitory compounds produced. The antibacterial activity of L. acidophilus IBB 801, L. amylovorus DCE 471, L. casei Shirota and L. rhamnosus GG was solely due to the production of lactic acid. The antibacterial activity of L. johnsonii La1 and L. plantarum ACA-DC 287 was due to the production of lactic acid and (an) unknown inhibitory substance(s). The latter was (were) only active in the presence of lactic acid. In addition, the lactic acid produced was responsible for significant inhibitory activity upon invasion of Salmonella into Caco-2/TC7 cells.

Caco-2 Cells↗
PubMed2000

Amino acid profiles after sprouting, autoclaving, and lactic acid fermentation of finger millet (Eleusine coracan) and kidney beans (Phaseolus vulgaris L.).

Seeds of finger millet (Eleucine coracan (L.) Gaertner) and kidney beans (Phaseolus vulgaris L.) were sprouted, autoclaved, and fermented during the processing of a weaning (complementary) food for children. Relative changes in individual amino acids with processing were evaluated. Finger millet and kidney beans both showed a good percentage of essential to total amino acids, with 44. 2-44.9% in finger millet and 44.2-45.1% in kidney beans, when compared to 33.9% for the FAO/WHO reference protein for 2-5 year old children. Sprouting resulted in a significant decrease in lysine in kidney beans. Autoclaving caused significant decreases in histidine, while fermentation significantly decreased phenylalanine and increased tryptophan in finger millet. The leucine-to-lysine ratio, which is an indicator of the pellagragenic character of a protein, was significantly improved in finger millet by both sprouting and fermentation.

Amino Acids↗
PubMed2003

Utilization for lactic acid production with a new acid hydrolysis of ram horn waste.

The use of ram horn hydrolysate (RHH) as a substrate for lactic acid production was investigated using Lactobacillus casei. For this purpose, first RHH was produced. Ram horns were hydrolyzed by treating with acids (6N-H2SO4 and 6N-HCl) and neutralizing the solutions. The amounts of protein, nitrogen, ash, some minerals, total sugars, total lipids and amino acids of the RHH were determined. The effect of different concentrations (1-10% v/v) of RHH on the production of biomass, lactic acid concentration and sugar consumption was investigated, and a concentration of 6% RHH was found to be optimal. The content of lactic acid in the culture broth containing 6% RHH (44 g x l(-1)) for 26 h was 22% higher than that of the control culture broth (36 g x l(-1)). From this result, RHH was demonstrated to be a suitable supplement for lactic acid production, a use that would resolve a local environmental problem.

Animals↗
PubMed2002

Production of L(+)-lactic acid from glucose and starch by immobilized cells of Rhizopus oryzae in a rotating fibrous bed bioreactor.

A rotating fibrous-bed bioreactor (RFB) was developed for fermentation to produce L(+)-lactic acid from glucose and cornstarch by Rhizopus oryzae. Fungal mycelia were immobilized on cotton cloth in the RFB for a prolonged period to study the fermentation kinetics and process stability. The pH and dissolved oxygen concentration (DO) were found to have significant effects on lactic acid productivity and yield, with pH 6 and 90% DO being the optimal conditions. A high lactic acid yield of 90% (w/w) and productivity of 2.5 g/L.h (467 g/h.m(2)) was obtained from glucose in fed-batch fermentation. When cornstarch was used as the substrate, the lactic acid yield was close to 100% (w/w) and the productivity was 1.65 g/L.h (300 g/h.m(2)). The highest concentration of lactic acid achieved in these fed-batch fermentations was 127 g/L. The immobilized-cells fermentation in the RFB gave a virtually cell-free fermentation broth and provided many advantages over conventional fermentation processes, especially those with freely suspended fungal cells. Without immobilization with the cotton cloth, mycelia grew everywhere in the fermentor and caused serious problems in reactor control and operation and consequently the fermentation was poor in lactic acid production. Oxygen transfer in the RFB was also studied and the volumetric oxygen transfer coefficients under various aeration and agitation conditions were determined and then used to estimate the oxygen transfer rate and uptake rate during the fermentation. The results showed that the oxygen uptake rate increased with increasing DO, indicating that oxygen transfer was limited by the diffusion inside the mycelial layer.

Bioreactors↗
PubMed2000

Production of lactic acid by Lactobacillus rhamnosus with vitamin-supplemented soybean hydrolysate.

Batch fermentation studies were performed to evaluate the potentials of a complex nitrogen source, soybean, as an alternative to yeast extract for the economical production of lactic acid by Lactobacillus rhamnosus. An enzyme-hydrolysate of soybean meal, Soytone, with an adequate supplementation of vitamins was found to be highly effective in supporting lactic acid production from glucose and lactose. The effects of seven selected vitamins: d-biotin, pyridoxine, p-aminobenzoic acid, nicotinic acid, thiamine, pantothenic acid, and riboflavin, on cell growth and lactic acid production were investigated to provide the basis for the optimization of vitamin supplementation to minimize the cost. Pantothenic acid was the most required compound while the other six vitamins were also essential for high lactic acid productivity. As a result of the optimization, 15 g/l yeast extract could be successfully replaced with 19.3 g/l Soytone supplemented with the vitamins, resulting in a production of 125 g/l lactic acid from 150 g/l glucose. The volumetric productivity and lactate yield were 2.27 g/l/h and 92%, respectively, which were higher than those with 15 g/l yeast extract. The raw material cost was estimated to be 21.4 cent/kg lactic acid, which was only approximately 41% of that with yeast extract.

Journal Article↗
PubMed2006

Lactic acid production from xylose by the fungus Rhizopus oryzae.

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)).

Cellulose↗
PubMed1995

The antimicrobial activity of lactic acid bacteria from fermented maize (kenkey) and their interactions during fermentation.

A total of 241 lactic acid bacteria belonging to Lactobacillus plantarum, Pediococcus pentosaceus, Lactobacillus fermentum/reuteri and Lactobacillus brevis from various processing stages of maize dough fermentation were investigated. Results indicated that each processing stage has its own microenvironment with strong antimicrobial activity. About half of the Lact. plantarum and practically all of the Lact. fermentum/reuteri investigated were shown to inhibit other Gram-positive and Gram-negative bacteria, explaining the elimination of these organisms during the initial processing stages. Further, widespread microbial interactions amounting to 85% to 18% of all combinations tested were demonstrated amongst lactic acid bacteria within the various processing stages, i.e. raw material, steeping, 0 h and 48 h of fermentation, explaining the microbial succession taking place amongst lactic acid bacteria during fermentation. The antimicrobial effect was explained by the combined effect of acids, compounds sensitive to proteolytic enzymes and other compounds with antimicrobial activity with the acid production being the most important factor. The pattern of antimicrobial factors was not species-specific and the safety and storage stability of fermented maize seem to depend on a mixed population of lactic acid bacteria with different types of antimicrobial characteristics. This means that introduction of pure cultures as starters may impose a risk to the product.

Anti-Bacterial Agents↗
PubMed2006

Batch fermentations on synthetic mixed sugar and starch medium with amylolytic lactic acid bacteria.

The green crop drying industry in Denmark uses Italian rye grass, clover, and alfalfa as raw materials for the production of green pellets. The green crop drying industry solves its energy economical problems by heating and pressing of the green crop before drying. The produced sidestream is called brown juice. Brown juice was shown to be an excellent medium for lactic acid fermentation. The aim of this study was to investigate the utilisation of brown juice in the production of polylactic acid, where wheat starch would be added to increase the lactic acid yield and, thus, the feasibility of the process. A number of amylolytic lactic acid bacteria have been identified, and in this work, six different strains were tested for their ability to produce alpha-amylase and to utilise all sugars with high lactic acid yield in a medium with a complex composition of free sugars (brown juice) and starch. Lactobacillus plantarum A6 was the only strain that showed both a good lactic acid production and utilisation of starch in this medium. The growth rate of this strain was approximately 0.4 h(-1) and the lactic acid yield was 0.7.

Carbohydrate Metabolism↗