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PubMed2004

Response of lactic acid bacteria to the digestive environment.

BACKGROUND: This article reviews several studies regarding adaptation to the digestive environment by lactic acid bacteria. The behavior of lactic acid bacteria in the digestive tract is worth investigating, and bacterial physiologic changes remain to be examined. METHODS: A genetic approach based on the fusion of bacterial promoters with genes of the reporter protein luciferase is described to screen for functions that lactic acid bacteria may suppress or activate in the digestive environment. RESULTS: Variations in luciferase expression from different promoters were observed in the digestive tract of mice models. In some cases, the promoter could be activated in response to an inducer provided with the diet. CONCLUSION: These data suggest that lactic acid bacteria are metabolically active in the digestive tract and can synthesize proteins to adapt to the digestive environment.

Animals↗
PubMed2005

Effect of enzymatic degradation on the release kinetics of model drug from Pluronic F127/poly(lactic acid) nano-particles.

Poly(lactic acid) (PLA) was successfully grafted to both ends of Pluronic F127 block copolymer (PEO-PPO-PEO) to obtain amphiphilic PLA-F127-PLA block copolymers. The effect of enzymatic degradation on the release behaviors of hydrophobic model drug 9-(methylaminomethyl)anthracene (MAMA) from PLA-F127-PLA nano-particles with vesicular structure was studied by UV-Vis spectroscopy. It was observed that the release rate of MAMA from PLA-F127-PLA nano-particles with the enzymatic degradation varied with temperature due to the activity of the enzyme with temperature. However, the enzyme concentration has negligible effect on the release rates of MAMA.

Anthracenes↗
PubMed2006

Environmental stress response in wine lactic acid bacteria: beyond Bacillus subtilis.

Lactic acid bacteria (LAB) constitute a heterogeneous group of bacteria that are traditionally used to produce fermented foods. The industrialization of food transformations has increased the economical importance of LAB, as they play a crucial role in the development of the organoleptic and hygienic quality of fermented products. However, the strains selected for industrial purposes, should tolerate adverse conditions encountered in industrial processes, either during starter handling and storage (freeze-drying, freezing, or spray-drying) or during food processing in which abiotic stresses such as heat, cold, acidity, and high concentration of NaCl or ethanol are common. Wine LAB have to deal with several stresses including an acidic pH, a high alcoholic content, non optimal growth temperatures, and growth-inhibitory compounds such as fatty acids and tannins, originated from yeast and bacteria metabolism. Wine LAB have developed several mechanisms to escape or to tolerate wine conditions. They carry out a malolactic fermentation in this stressful environment. In addition to the regulation of the expression of specific genes, bacteria have evolved adaptive networks to face the challenges of a changing environment and to survive under conditions of stress. The so called Global Regulatory Systems control the simultaneous expression of a large number of genes in response to a variety of environmental stress factors. CIRCE sequences able to bind the HrcA repressor, sigma(B) dependent promoters and CtsR regulatory elements have been observed in several genes identified from wine LAB. Improved knowledge of regulators and a better understanding of LAB stress responses could constitute a basis of comparison with the well known model microorganisms, Escherichia coli and Bacillus subtilis. Moreover, it can provide an important insight into improving current industrial starter strains.

Bacillus subtilis↗
PubMed1999

The neural mechanism of rectal motility response induced by the epicardial application of lactic acid.

The epicardial application of lactic acid induced a biphasic rectal motility response in lightly anaesthetised, open-chested and artificially ventilated cats. This rectal biphasic response is reflexogenic in nature as epicardial lignocaine abolished such response. This rectal biphasic response is abolished by cardiac sympathectomy and reprecipitated by left inferior cardiac afferent nerve stimulation. Such response is also abolished by sacral ventral rhizotomy and reproduced by stimulation of the peripheral cut end of split sacral ventral roots. This indicates that the afferent and efferent pathways for such reflex are lying in the cardiac sympathetic and sacral pelvic nerves, respectively. The higher centers involved for such reflex are lying above the mid-collicular level of the brain as decerebration at the mid-collicular level completely abolished such type of rectal response. Furthermore, the relaxation phase and contraction phase of such rectal response are mediated through nitric oxide release and cholinergic neurones, respectively, as NG-nitro-L-arginine and atropine abolished relaxation and contraction phase of the rectal response, respectively.

Animals↗
PubMed1990

Controlled release of 3',5'-diester prodrugs of 5-fluoro-2'-deoxyuridine from poly-L-lactic acid microspheres.

Poly-L-lactic acid (MW 6000) microspheres (PLA-MS) containing 5-fluoro-2'-deoxyuridine (FUdR) or four ester prodrugs of FUdR were prepared and examined with regard to the in vitro release kinetics. The incorporation efficiency of the lipophilic prodrugs into the PLA-MS was higher than that of FUdR or the hydrophilic prodrugs. The release of the lipophilic FUdR prodrugs from PLA-MS was sustained as compared with that of FUdR from PLA-MS. The release kinetics of the FUdR prodrugs appears to fit the Higuchi, Baker, and Lonsdale model in the early stage of the release process. The slope of the Baker and Lonsdale plots of the release of divaleryl-FUdR from PLA-MS decreased as the initial drug loading was decreased. The order of the release rates of FUdR prodrugs from PLA-MS with the same prodrug content was similar to that of the water solubilities of the prodrugs. These results suggest that the ester prodrugs could be released from PLA-MS by diffusion through water-filled capillaries or a series of pores rather than by diffusion through the PLA matrix.

Chemical Phenomena↗
PubMed1994

Effect of lactic acid on the kinetics of growth and antibody production in a murine hybridoma: secretion patterns during the cell cycle.

The effects of elevated lactic acid concentration on the cell cycle kinetics of hybridoma cell growth and antibody production in batch culture were studied using conventional methods based on population-average data analysis and using flow cytometry based on single-cell data analysis. When 33 mM lactic acid was initially present, the true specific growth rate was reduced by 37% and the cell specific antibody production rate increased by a factor of 2.6 relative to a control culture with no additional lactic acid. DNA content distribution measured during balanced exponential growth were not affected by lactic acid concentration indicating lactic acid has a uniform effect on cell growth throughout the cell cycle. There was little or no effect on single-cell distributions of intracellular antibody content measured for the total population and for each cell cycle phase. The net rate of total antibody synthesis was found to be independent of specific growth rate. This implies that the balance of the total amount of antibody synthesized is shifted from cellular accumulation towards secretion when specific growth rate decreases. Our data predict that a maximum specific secretion rate of 2.7 pg per cell per h could be achieved if the specific growth rate was reduced to zero. The rates of secretion in the G1 and S phases increased with decreasing specific growth rate, while the rate of secretion in the G2+M phase remained relatively constant. Under the assumptions that (a) at the fastest growth rate, secretion in the G1 phase is negligible and (b) the rate of synthesis increases exponentially as cells proceed from the S phase to the G2+M phase, our data predict that for the slowest growth rate, the rate of secretion in G2+M is approx. 3-times that in the G1 phase and 5-times that in the S phase.

Animals↗
PubMed2004

Simultaneous production of nisin and lactic acid from cheese whey: optimization of fermentation conditions through statistically based experimental designs.

A biorefinery process that utilizes cheese whey as substrate to simultaneously produce nisin, a natural food preservative, and lactic acid, a raw material for biopolymer production, was studied. The conditions for nisin biosynthesis and lactic acid coproduction by Lactococcus lactis subsp. lactis (ATCC 11454) in a whey-based medium were optimized using statistically based experimental designs. A Plackett-Burman design was applied to screen seven parameters for significant factors for the production of nisin and lactic acid. Nutrient supplements, including yeast extract, MgSO4, and KH2PO4, were found to be the significant factors affecting nisin and lactic acid formation. As a follow-up, a central-composite design was applied to optimize these factors. Second-order polynomial models were developed to quantify the relationship between nisin and lactic acid production and the variables. The optimal values of these variables were also determined. Finally, a verification experiment was performed to confirm the optimal values that were predicted by the models. The experimented results agreed well with the model prediction, giving a similar production of 19.3 g/L of lactic acid and 92.9 mg/L of nisin.

Cell Culture Techniques↗
PubMed1988

Cardiorespiratory responses to HCl vs. lactic acid infusion.

Previous reports indicate that intravenous infusion of HCl can alter breathing and blood pressure even if reductions in systemic arterial pH are prevented. To extend these findings, as well as to determine whether other acids elicit comparable results, this report compares the cardiopulmonary response between right atrial infusion of lactic acid and HCl in awake ponies. Lactic acid, infused at a dose of 1.5 mmol/kg over 18 min, lowered systemic and pulmonary arterial pH 0.062 and 0.092 U, respectively, and increased pulmonary arterial pressure (delta Ppa, 4 mmHg), heart rate (HR, 4/min), and tidal volume (delta VT, 190 ml/m2). HCl, infused at a reduced dose of 0.5 mmol/kg over 18 min, lowered systemic and pulmonary arterial pH 0.024 and 0.047 U, respectively, but produced increases in Ppa (delta 23 mmHg), HR (delta 42/min), and VT (delta 321 ml/m2) that were significantly greater than from the larger dose of lactic acid. These results indicate that cardiopulmonary responses to infusion acidosis differ between the type of acid infused. It is suggested that, in the unanesthetized pony, HCl-induced infusion acidosis has a unique cardiopulmonary-stimulating action unrelated to the pH changes imparted to the circulating arterial blood and that this response is absent during the infusion of lactic acid.

Animals↗
PubMed2002

Lactic acid production from wheat straw hemicellulose hydrolysate by Lactobacillus pentosus and Lactobacillus brevis.

Lactic acid production by Lactobacillus brevis and Lactobacillus pentosus on a hemicellulose hydrolysate (HH) of wet-oxidized wheat straw was evaluated. The potential of 11-12 g/l fermentable sugars was released from the HH through either enzymatic or acidic pretreatment. Fermentation of added xylose in untreated HH after wet-oxidation, showed no inhibition on the lactic acid production by either Lb. pentosus or Lb. brevis. Lb. pentosus produced lactate corresponding to 88% of the theoretical maximum yield regardless of the hydrolysis method, whereas Lb. brevis produced 51% and 61% of the theoretical maximum yield after enzymatic, or acid treatment of HH, respectively. Individually, neither of the two strains were able to fully utilize the relatively broad spectra of sugars released by the acid and enzyme treatments; however, lactic acid production increased to 95% of the theoretical maximum yield by co-inoculation of both strains. Xylulose was the main sugar released after enzymatic treatment of HH with Celluclast. Lb. brevis was able to degrade xylobiose, but was unable to assimilate xylulose, whereas Lb. pentosus was able to assimilate xylulose but unable to degrade xylobiose.

Fermentation↗
PubMed1990

Field studies on the potential of butanone, carbon dioxide, honey extract, 1-octen-3-ol, L-lactic acid and phenols as attractants for mosquitoes.

Various combinations of six candidate attractants--butanone, carbon dioxide (CO2), honey, octenol, lactic acid and mixed phenols--were tested against natural populations of mosquitoes in Everglades National Park, Florida, U.S.A., using unlighted CDC-baited traps. With few exceptions, the attractancy of these candidate compounds to mosquitoes, when used alone, was less than that of CO2 alone. The exceptions were that octenol and honey extract alone attracted larger numbers of Coquillettidia perturbans (Walker). Addition of lactic acid and/or octenol to CO2 increased trap collections of Aedes taeniorhynchus (Wiedemann), Anopheles atropos D. & K., and An. crucians Wiedemann by 1.4-13.8 times. Culex nigripalpus Theobald collections were increased 2.7 times by the addition of lactic acid, while the addition of octenol produced mixed results. Whereas the addition of lactic acid reduced collections of Cx (Melanoconion) spp., the addition of octenol generally increased collections. The opposite happened for Wyeomyia mitchellii (Theobald). For the biting midge, Culicoides furens (poey), octenol (1.6-23.4 x ) and phenol (2.7 x ) alone attracted larger numbers, and lactic acid alone attracted approximately the same numbers as CO2 alone. The combinations octenol + phenol and octenol + 200 ml/min CO2 increased C. furens collections c. 100 times over CO2 alone. The combination of octenol + CO2 increased (1.6 x ) collections of the tabanid Diachlorus ferrugatus (Fabricius). Butanone appeared to decrease the trap collections of all species when combined with CO2 or octenol + CO2.

Animals↗
PubMed2006

Lactic acid bacteria associated with wine grapes from several Australian vineyards.

AIMS: The detection and isolation of lactic acid bacteria by enrichment methods from wine grapes cultivated in vineyards located in New South Wales, Australia. METHODS AND RESULTS: Enrichment cultures in de Man, Rogosa and Sharpe (MRS) broth, MRS + ethanol (5%), MRS broth supplemented with 15% (v/v) tomato juice (MRST), pH 5.5 and 3.5 and autoenrichment in grape juice homogenate were used to detect lactic acid bacteria on wine grapes. Bacteria were isolated from enrichment cultures by plating onto MRS and MRST agar and identified by 16S rDNA sequence analysis and phenotypical methods. A molecular method, PCR-denaturing gradient gel electrophoresis (DGGE) was also used to examine the bacteria that developed in enrichment cultures. Species of Lactobacillus, Enterococcus, Lactococcus and Weissella were detected in enrichments by plating and PCR-DGGE. Other bacteria (Sporolactobacillus, Asaia, Bacillus ssp.) were also found in some enrichment cultures. The principal malolactic bacterium, Oenococcus oeni, was not isolated. CONCLUSIONS: The incidence and populations of lactic acid bacteria on wine grapes were very low. Damaged grape berries showed a greater presence of these bacteria than undamaged berries. The diversity of bacterial species isolated from the grapes was greater than those previously reported and represented both lactic acid bacteria and nonlactic acid bacteria. Some of these bacteria (i.e. Lactobacillus lindneri, Lactobacillus kunkeei) could be detrimental to wine production. Oenococcus oeni was not found on grapes, but its recovery could be obscured by overgrowth from other species. SIGNIFICANCE AND IMPACT OF THE STUDY: Lactic acid bacteria are significant in wine production because they conduct the malolactic fermentation and cause stuck or sluggish alcoholic fermentation and wine spoilage. This study investigates wine grapes as a potential source of these bacteria.

Culture Media↗
PubMedDate not supplied

[The adhesion of lactic acid bacteria to the intestinal epithelium of agricultural animals].

The lactic acid bacteria isolated from different ecological niches are established to be able to adhere in vitro to the intestine epithelium of pigs and cattle. The studied strains of enterococci have a higher index of adhesiveness (5.7-2.24) as compared to lactic acid bacilli (3.34-1.08). Detection of the lactic acid bacteria ability to adhere to intestine enterocytes of agricultural animals served as a premise to use those bacteria when constructing preparations of the directed action on the basis of living cultures.

Animal Feed↗
PubMed2005

Joint effect of nitrogen sources and B vitamin supplementation of date juice on lactic acid production by Lactobacillus casei subsp. rhamnosus.

The use of date juice as a substrate for lactic acid production was investigated. Various nitrogen sources were compared with yeast extract for efficient lactic acid production by Lactobacillus casei subsp. rhamnosus. Among different nitrogen sources added to date juice (yeast extract, ammonium sulfate, tryptic soy, urea, peptone, and casein hydrolysate), yeast extract was the most efficient. The effect of yeast extract could have been due to its B vitamin content. The addition of five B vitamins at less than 25 mg/l to date juice with any nitrogen source enhanced lactic acid production to some extent, except for date juice with yeast extract or urea or peptone. The most significant increase was obtained with ammonium sulfate. Half of the yeast extract content (10 g/l) in a supplemented date juice could be replaced by a mixture of B vitamins at less than 25 mg/l, and ammonium sulfate at 2.6 g/l with no significant decrease in lactic acid production.

Ammonium Sulfate↗
PubMed1994

L(+)-lactic acid production in plaque from orthodontic appliances retained with glass ionomer cement.

The lactic acid production in suspensions of plaque collected adjacent to orthodontic brackets retained with a glass ionomer cement (GIC), or a resin-based composite was investigated using a split-mouth technique. Forty-eight-hour-old plaque was collected at 3, 8, and 28 days, and 3 months after the onset of orthodontic treatment. Acid fermentation was induced by glucose and the L(+)-lactic acid concentrations were determined enzymatically after a 30-minute incubation period. Significantly (P < 0.05) lower levels of lactic acid were found in plaque from GIC-retained brackets compared with the composite controls at the 28 days and 3 months sampling occasions, respectively. The results suggest that the use of GIC as a bonding agent in orthodontics can be beneficial for patients assessed at risk of caries development.

Acrylic Resins↗
PubMed2001

The lactic acid response to alkalosis in panic disorder : an integrative review.

Panic patients consistently show exaggerated lactic acid response to alkalosis, whether produced by hyperventilation or by sodium lactate infusion. Understanding why this occurs may provide important clues to the pathogenesis of panic disorder. Although brain hypoxia from excessive hypocapnia-induced cerebral vasoconstriction is often cited as the mechanism of elevated brain lactic acid in panic disorder, studies of brain metabolism show that hypocapnia rarely leads to brain hypoxia. Increased lactic acid production is a normal response to intracellular alkalosis and to intracellular cyclic AMP. Thus, other possible mechanisms of the exaggerated lactic acid response in panic disorder include a disturbance of mechanisms regulating intracellular pH and factors increasing intracellular cyclic AMP. Both mechanisms are consistent with the suffocation false alarm theory of panic disorder. This review suggests a theoretical framework for future magnetic resonance spectroscopy studies that can test some of the predictions of these competing models.

Alkalosis↗
PubMed2005

Efficient lactic acid production from high salt containing dairy by-products by Lactobacillus salivarius ssp. salicinius with pre-treatment by proteolytic microorganisms.

Lactic acid bacteria have an inefficient proteolytic system. Therefore, cultivation media which may have high protein content are usually supplemented with yeast extract or protein lysates (peptones). These additives might be conveniently replaced by in situ treatment of the cultivation medium with proteolytic enzymes or proteolytic microbes. Lactobacillus salivarius ssp. salicinius, a lactic acid bacterium species that can grow at high salt concentration, was used to ferment lactic acid in cheese whey (with 3 gl(-1) whey protein content) and lactose mother liquor (90 gl(-1) lactose, 9 gl(-1) proteins, 30 gl(-1) minerals). The contribution of protease enzymes or proteolytic microbes to acid production by lactobacilli was examined. Efficient conversion of lactose to lactic acid was obtained in the presence of additional proteolytic activity. Fastest acid production was obtained with the addition of protease enzymes. However, almost equally efficient acid production was obtained by treating the medium with Bacillus megaterium. The results show that fast and complete conversion of lactose to lactic acid can be obtained in dairy by-products without expensive additives.

Bacillus megaterium↗
PubMed2001

Bone response to polymers based on poly-lactic acid and having different degradation times.

Authors studied two degradable and resorbable polymers derived from lactic acid: poly-L-Lactic acid (PLLA), with a relatively long time of degradation (longer than 6 months, PL10 Purac NL); poly-DL-Lactic acid (PDLLA), with a relatively short time of degradation (shorter than 6 months, PDL Purac NL). The animal species was the young adult New Zealand White rabbit. The in-vivo study was performed by implantation of small cylinders of 10 x 3 mm in size (length x diameter) in the distal metaepiphysis of the femur; 34 cylinders have been implanted. Retrievals of PLLA specimens took place at 3, 6, 9, 12 and 24 months; for PDLLA specimens at 1, 2, 4 months. Polarized light microscopy of undecalcified tissue sections was performed. The analysis for PLLA and PDLLA has shown a favorable response of bone tissue: alterations in the bone repair, growth and remodeling have not been observed. PLLA is persistent at the times studied; there is never a tight apposition between bone and PLLA implant and an intervening fibrous layer has often been observed. PDLLA is not persistent at the times studied and it degrades quite fast; bone repair of the empty implantation's hole occurs by bony growth from the endosteal trabeculae. The newly formed bone covers the hole's walls with an elongation parallel to them. For both polymers, whether the degradation is fast or slow, the material's substitution by newly formed bone never starts from the walls of the implantation hole. Only after the complete disappearance of the polymeric material newly formed bone begins to fill the hole.

Journal Article↗
PubMed1989

D-lactic acid measurements in the diagnosis of bacterial infections.

Body fluids suspected of bacterial infection were cultured and examined for the presence of D-lactic acid, a specific bacterial metabolite. We examined 206 patients and 264 specimens. D-Lactic acid was found in concentrations of greater than or equal to 0.15 mM in 11 of 11 infected and 6 of 40 noninfected ascitic fluids, 6 of 6 infected and 4 of 33 noninfected pleural fluids, 4 of 4 infected and 0 of 13 noninfected synovial fluids, and 26 of 27 infected and 2 of 130 noninfected cerebrospinal fluids. The overall sensitivity was 79.7%, and the specificity was 99.5% when the D-lactic acid concentration was at least 0.15 mM. The most important clinical utility of the D-lactic acid measurement appears to be for patients with bacterial infection in various body compartments and in patients who have already received antimicrobial therapy. An elevation in D-lactic acid may indicate the presence of bacterial infection even when cultures are negative.

Ascitic Fluid↗