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PubMed1991

Distribution and purification of aspartate racemase in lactic acid bacteria.

The distribution of aspartate racemase (EC 5.1.1.13) in various kinds of bacteria demonstrated that the enzyme occurs in lactic acid bacteria, such as Streptococcus species and Lactobacillus species. The enzyme from Streptococcus thermophilus IAM10064 was more thermostable than that from Streptococcus lactis IAM1198 which contained the enzyme most abundantly among the lactic acid bacteria we examined here. We purified the enzyme about 3400-fold to homogeneity from cell-free extract of S. thermophilus, which is composed of two identical subunits with a molecular weight of 28,000 as a homodimer. The enzyme utilizes specifically aspartate as a substrate, but not alanine and glutamate. Maximal reaction velocity was observed at 37 degrees C and around pH 8.0. The sequence of the NH2-terminal amino acids of the enzyme was determined to be Met-Glu-Asn-Phe-Phe-Ser-Ile-Leu-Gly-XXX-Met-Gly-Thr-Met-Ala-Thr-Glu-Ser- Phe-.

Amino Acid Isomerases↗
PubMed1975

[Efficacy of aerosol disinfection with lactic acid and its effect on the body of poultry].

Comparative studies were carried out to establish the efficacy of lactic acid as a disinfection means. The following pattern was observed in employing the agent: a 20 per cent conc. of the acid at the rate of 20 cu. cm per cubic meter is dispersed three times as an aerosol (at 8, 12, and 6 oclock) in the course of twenty minutes. It was found that the microbial contamination of the air drops three to four times. More pronounced is the bactericidal effect on the coliforms and moulds. The birds of the group treated with lactic acid gain 30 g more per day up to the end of the fattening period. Dependable is the higher serum level of protein as well as the higher protein content of the liver and heart musculature and of the essential amino acid tryptophane in the blood serum and liver of the test birds. Higher was also the glycogen content of the liver of the test group broilers.

Aerosols↗
PubMed2004

Evaluation of meat born lactic acid bacteria as protective cultures for the biopreservation of cooked meat products.

In this study, 91 strains, originating from meat products, were subjected to a step-by-step screening and characterisation to search for potential protective cultures to be used in the cooked cured meat industry. Strains were first tested on their homofermentative and psychrotrophic character and salt tolerance. Secondly, the antibacterial capacities towards Listeria monocytogenes, Leuconostoc mesenteroides, Leuconostoc carnosum and Brochotrix thermosphacta were determined in an agar spot test. In total, 38% of the tested strains were inhibitory towards all indicator strains. However, 91%, 88% and 74% of the strains could inhibit, respectively, L. monocytogenes, B. thermosphacta and Leuc. mesenteroides. Finally, 12 strains, with the highest antibacterial capacities, were evaluated on their competitive nature by comparing their growth rate, acidifying character and lactic acid production at 7 degrees C under anaerobic conditions in a liquid broth. All 12 strains, except for a bacteriocin producing Lactobacillus plantarum strain and the lactocin S producing Lactobacillus sakei 148, combined a fast growth rate with a deep and rapid acidification caused by the production of high levels of lactic acid. The 12 selected strains were then further investigated for their growth capacity on a model cooked ham product to establish whether the presence of these cultures on the ham did not negatively influence the sensory properties of the ham. All strains grew in 6 days at 7 degrees C from a level of 10(5)-10(6) to 10(7)-10(8) cfu/g and again the bacteriocin producing L. plantarum strain was the slowest growing strain. As the glucose level of the model cooked ham product was low (0.09+/-0.03%), growth of the putative protective cultures resulted in glucose depletion and a limited lactic acid production and accompanying pH decrease. Cooked ham inoculated with isolates 13E, 10A, 14A (all three identified as L. sakei subsp. carnosus by SDS-PAGE) and with strains L. sakei 148 (LS5) and L. sakei subsp. carnosus SAGA 777 (LS8) were not rejected by the sensory panel at the 34th day of the vacuum packaged storage at 7 degrees C. Therefore, these strains could have potential for the use as protective culture in cooked meat products.

Animals↗
PubMedDate not supplied

The role of lactic acid bacteria in colon cancer prevention: mechanistic considerations.

Colorectal cancer is one of the most important causes of cancer morbidity and mortality in Western countries. While a myriad of healthful effects have been attributed to the probiotic lactic acid bacteria, perhaps the most controversial remains that of anticancer activity. It should be pointed out already at this point that there is no direct experimental evidence for cancer suppression in humans as a result of consumption of lactic cultures in fermented or unfermented dairy products. However, there is a wealth of indirect evidence, based largely on laboratory studies, in the literature. The precise mechanisms by which lactic acid bacteria may inhibit colon cancer are presently unknown. However, such mechanisms might include: enhancing the host's immune response; binding and degrading potential carcinogens; quantitative and/or qualitative alterations in the intestinal microflora incriminated in producing putative carcinogen(s) and promoters (e.g. bile acid-degrading bacteria); producing antitumorigenic or antimutagenic compounds in the colon; alteration of the metabolic activities of intestinal microflora; alteration of physicochemical conditions in the colon; effects on physiology of the host. These potential mechanisms are discussed in the present paper.

Animals↗
PubMed1998

Prevention of peroxidative stress in rats fed on a low vitamin E-containing diet by supplementing with a fermented bovine milk whey preparation: effect of lactic acid and beta-lactoglobulin on the antiperoxidative action.

We examined the antiperoxidative properties of a fermented bovine milk whey preparation in rats fed on a low vitamin E-containing diet and identified the active principle in the preparation. An exogenous supply of either lactic acid or an amino acid mixture simulated the unfermented whey proteins to prevent red blood cell (RBC) hemolysis and to lower liver thiobarbituric acid reactive substances (TBARS). The supply of either whey proteins or beta-lactoglobulin resulted in an increase in liver GSH and prevented iron-mediated lipoprotein peroxidation. These protein effects were reproduced in rats orally administered with either GSH or its precursor, gamma-glutamylcysteine. The amount of TBARS formed during in vitro lipoprotein peroxidation were positively correlated with liver TBARS. These results suggest that fermented milk products containing lactic acid and bovine milk whey proteins can ameliorate peroxidative stress in tissues subjected to vitamin E deficiency.

Animals↗
PubMed1984

Clinical utility of lactic acid measurement in body fluids other than plasma.

The diagnosis of septic infections of closed body cavities requires a careful search. Traditional laboratory tests such as Gram's stain, white cell count, and protein and glucose levels are often inconclusive. Measurement of lactic acid in cerebrospinal, synovial, pleural, ascitic, and bursal fluids has been utilized to distinguish bacterial from nonbacterial infections. The present review summarizes the current status of lactic acid measurement in the differential diagnosis of meningitis, arthritis, empyema, bacterial peritonitis, and bursitis.

Ascitic Fluid↗
PubMed2005

L(+)-lactic acid production using Lactobacillus casei in solid-state fermentation.

Lactobacillus casei was grown at 37 degrees C on sugarcane bagasse (5 g) soaked with cassava starch hydrolysate (final moistening volume 34 ml) containing 3 g reducing sugar in a solid-state condition. The maximum yield of L-lactic acid after various process optimisations was 2.9 g/5 g initial substrate corresponding to 97% conversion of sugar to lactic acid with initial substrate moisture of 72%.

Biomass↗
PubMed1998

Detection of specific bacteriocin-producing lactic acid bacteria by colony hybridization.

A colony hybridization method for detecting lactic acid bacteria encoding specific bacteriocins was developed. Specific PCR-generated probes were used to detect colonies of pediocin PA-1, lactococcin A, enterocin AS-48, nisin A and lacticin 481 producing strains. The probes were shown to be sensitive and specific for sequences belonging to the structural genes of the respective bacteriocins.

Bacteriocins↗
PubMed2004

Development of a new method, based on a bioreactor coupled with an L-lactate biosensor, toward the determination of a nonspecific inhibition of L-lactic acid production during milk fermentation.

The development and characteristics of a bioreactor employing bacteria (Streptococcus thermophilus) encapsulated in Ca-alginate beads coupled with an L-lactate biosensor are reported. The biosensor comprises a carbon paste electrode modified with enzymes HRP (horseradish peroxidase), LOD (lactate oxidase), and FcH (ferrocene) as redox mediator. The measurement of L-lactate is based on the signal produced by H(2)O(2), the product of the enzymatic oxidation of L-lactate by LOD. The detection of H(2)O(2) is performed at the electrode surface via HRP/FcH at low operating potential (-100mV vs Ag/AgCl). Optimization studies were performed using the bioreactor in conjunction with an L-lactate electrode operating in a flow injection system to assess the ability of encapsulated bacteria to ferment carbohydrate solutions. The possibility of using the developed method to assess the fermentation capability of milk samples was evaluated. Bronopol (2-bromo-2-nitro propane-1,3-diol) was chosen to simulate the effect of an inhibitory agent of milk fermentation. The obtained results indicated that the evaluation of the amount of L-lactate amount produced through the bioreactor could be used as a measure of inhibition of lactic acid production in milk samples.

Alginates↗
PubMed1992

Evaluation of poly(L-lactic acid) as a material for intravascular polymeric stents.

Poly(L-lactic acid) (PLLA) monofilaments were evaluated for use as intravascular polymeric stents. The PLLA monofilaments were extruded and drawn to different draw ratios. They were then subjected to different thermal treatments and their mechanical properties characterized. Stents constructed with similar monofilaments were tested under hydrostatic pressure, and the results correlated with the properties of the monofilaments. Stent collapse pressure was a decreasing function of stent diameter and filament draw ratio.

Biocompatible Materials↗
PubMed1998

Binding of heterocyclic amines by lactic acid bacteria from miso, a fermented Japanese food.

Miso, a widely used Japanese fermented food was analysed for its lactic acid bacterial count on bromocresol purple agar. The binding of eight different foodborne carcinogenic heterocyclic amines to 25 bacterial isolates from miso were investigated. The heterocyclic amines used were 3-amino-1,4-dimethyl[5H]pyrido(4,3-b)indole (Trp-P-1), 3-amino-1-methyl[5H]pyrido(4,3-b)indole (Trp-P-2), 2-amino-6-methyldipyrido(1,2-a:3'2'-d)imidazole (Glu-P-1), 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP), 2-amino-dimethylimidazo(4,5f)quinoline (IQ), 2-amino-3,4-dimethylimidazo(4,5-f) quinoline (MeIQ), 2-amino-3,8-dimethylimidazo(4,5-f)quinoxaline (MeIQx), and 2-amino-3-methyl-9H-pyrido(2,3)indole (MeA alpha C). The lyophilized cells of all of the isolates exhibited high binding activity towards Trp-P-1, Trp-P-2, MeA alpha C, and PhIP, while Glu-P-1 and IQ were not effectively bound. Of the isolates tested, the strongest and weakest binders were identified as Pediococcus acidilactici 1 and 2, respectively. Lyophilized cell wall fractions, heat-treated cells, and the cytoplasmic contents of P. acidilactici 1 and 2 were analysed for their ability to bind to different mutagens. Pure cell wall and peptidoglycan showed greater binding activity than the bacterial cells. Cytoplasmic content also showed some binding, but it was much less effective. The impact of enzymes (amylase, protease, cellulase, chitinase, muraminase, and peptidase) and acetylation of Trp-P-1 and IQ on the binding action of bacteria and cell wall material were also analysed to understand the possible processes involved in the binding of lactic acid bacteria to carcinogenic heterocyclic amines.

Amines↗
PubMed2001

Prevention by lactic acid bacteria of the oxidation of human LDL.

Ether extracts of lactic acid bacteria were analyzed for prevention of the oxidation of erythrocyte membrane and human low-density lipoprotein in vivo. Streptococcus thermophilus 1131 and Lactobacillus delbrueckii subsp. bulgaricus 2038, yogurt starters, were chosen as test-strains, and ether extracts of these cultures were used as samples. Both strain 1131 and strain 2038 produced radical scavengers and inhibited oxidation of erythrocyte membranes and low-density lipoproteins. The antioxidative activity of strain 2038 was higher than that of strain 1131.

Adult↗
PubMedDate not supplied

Nanoparticle DNA carrier with poly(L-lysine) grafted polysaccharide copolymer and poly(D,L-lactic acid).

Biodegradable nanoparticles, which contain the sites for both polynucleotide adsorption and targeting ligand on their surfaces, were prepared as a novel carrier for genetic materials. The nanoparticles were obtained from poly(D,L-lactic acid) and poly(L-lysine)-graft-polysaccharide copolymers by using either a solvent evaporation method or a diafiltration method. The size of the particles prepared by the diafiltration method was controlled by varying the initial concentration of the graft copolymer. Nanoparticles as small as 60 nm in diameter were successfully obtained from the graft copolymers with high polysaccharide contents but not from the poly(L-lysine) homopolymer. Polysaccharide moieties on the surface of the nanoparticles were found to interact specifically with a particular lectin as verified by the aggregation assay. The polynucleotide adsorption capacity of the nanoparticles was increased with increasing polysaccharide contents in the graft copolymers, suggesting that the adsorption conformation of poly(L-lysine) moiety in the graft copolymer on the nanoparticle surface is different from that in poly(L-lysine) homopolymer. Moreover, the nanoparticles from the graft copolymer exhibited resistance against self-aggregation and nonspecific adsorption of serum proteins, presumably due to the polymer brush effect and/or exclusion effect from the polysaccharide graft chains. These results suggest that the nanoparticles prepared from poly(L-lysine)-graft-polysaccharide copolymer and poly(D,L-lactic acid) can serve as a good DNA carrier in vivo.

Adsorption↗
PubMed1989

Endocardial damage induced by lactate, lowered pH and lactic acid in non-ischemic beating hearts.

The left ventricular lumen of isolated perfused beating hearts was perfused for up to 8 h with either Krebs Henseleit buffer (KHB, pH 7.4), KHB including 33 mumol/ml of lactic acid at pH 7.4 or 6.4, or with KHB including hydrochloric acid to reduce the pH to 6.4. Scanning and transmission electron microscopy showed that whereas control hearts maintained an intact endocardium, those groups exposed to increased concentrations of lactate, hydrogen ions or both, developed endothelial cell separation and exfoliation with exposure first of basal lamina and then of endocardial collagen. The underlying myocytes also showed evidence of irreversible cell injury. The extent and severity of damage was greater in hearts exposed to lactic acid than to either lactate or lowered pH alone. These findings suggest that the increased concentrations of metabolites which accumulate in developing myocardial infarcts can diffuse through and damage the endocardium in ways which are likely to predispose in vivo to the development of mural thrombosis.

Acidosis↗
PubMed1991

Use of low molecular mass RNA profiles to identify lactic acid bacteria and related organisms associated with foods.

Fourteen strains of lactic acid bacteria and species of Brochothrix, Carnobacterium, Enterococcus, Erysipelothrix, Kurthia and Listeria were examined using low molecular mass RNA (5S rRNA and tRNA) profiles. These profiles were developed on denaturing polyacrylamide gels. Gel strengths between 9 and 14% were tested to improve resolution of distinct bands for densitometrical analysis. Profiles generated on 12% gels proved to be the best for scanning. Scans of class 2 tRNAs by densitometry showed a characteristic profile for each genus. In the case of Lactobacillus each species studied gave a unique profile. The technique of low molecular mass RNA profiling may provide a useful means for identifying different bacteria from ecosystems such as meats.

Culture Media↗
PubMed2005

[A study on cytocompatibility of poly (lactic acid) membrane modified by polymer microspheres with different surface charges].

Poly(lactic acid) microspheres with different surface charges have been prepared by using cationic, anionic or nonionic surfactants as the microspheres' surface stabilizers. Embedded with these microspheres, the modified PLA membranes with different surface charges have been obtained. The test of stability by CLSM and the morphological test by SEM confirmed that we obtained the microspheres modified PLA membranes with different surface charges successfully. The chondrocyte compatibility test of these modified PLA membranes showed that the attachment, proliferation and activity of chondrocytes on the positive surface of the modified PLA were better than those of other modified PLA membranes. The positive charge on the surface of PLA membrane could improve the cell-compatibility of PLA well.

Animals↗
PubMed1998

In vivo characteristics of injectable poly(DL-lactic acid) microspheres for long-acting drug delivery.

Poly(DL-lactic acid) (PLA) microspheres containing testosterone (T) were prepared by the solvent evaporation process to evaluate their physical properties such as size distribution, shape, drug content, in vivo controlled drug release, pharmacological influences on the prostate gland in castrated rats, and histopathological findings of tissues surrounding the implants. The in vivo release of T from PLA microspheres containing 30 mg of drug obtained with chloroform was continued over a 6-week period. This effect is attributed to high dispersibility of T in the device when obtained with chloroform. Both serum drug levels and prostate gland weight recovery suggested the effects of a long-acting drug delivery system. The histopathological findings showed that the devices used were completely degraded 10 weeks after injection.

Animals↗
PubMedDate not supplied

Anchoring of proteins to lactic acid bacteria.

The anchoring of proteins to the cell surface of lactic acid bacteria (LAB) using genetic techniques is an exciting and emerging research area that holds great promise for a wide variety of biotechnological applications. This paper reviews five different types of anchoring domains that have been explored for their efficiency in attaching hybrid proteins to the cell membrane or cell wall of LAB. The most exploited anchoring regions are those with the LPXTG box that bind the proteins in a covalent way to the cell wall. In recent years, two new modes of cell wall protein anchoring have been studied and these may provide new approaches in surface display. The important progress that is being made with cell surface display of chimaeric proteins in the areas of vaccine development and enzyme- or whole-cell immobilisation is highlighted.

Bacterial Proteins↗