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PubMedDate not supplied

Influence of aflatoxin B1 on gas production by lactic acid bacteria.

The main characteristic of homofermentative lactic acid bacteria is that they do not produce gas from glucose and other sugars. However, in these experiments Lactobacillus casei, Lb. plantarum and Streptococcus lactis in broth media with glucose, galactose, lactose and sucrose, and aflatoxin B1 produces acid and also a significant amount of gas. In the control media without aflatoxin, these bacteria did not produce gas. The data suggest that lactic acid bacteria, known until now as homofermentative, become heterofermentative because of the influence of aflatoxin B1. The results of these investigations are of practical value because they may explain the defect of cheese "blowing," which can appear in Trapist cheese vacuum packed in foil. This type of unusual "blowing" occurs approximately one month after cheese manufacture. This defect can be characterized by very large holes and cracks inside the cheese. The flavor is similar to that of young cheese, which can be very undesirable for a ripened, Trapist, aged cheese.

Aflatoxin B1↗

PubMed2006

Preparation of poly(lactic acid) composite hollow spheres containing calcium carbonates.

Poly(lactic acid) composite hollow spheres containing calcium carbonate were prepared by oil-in-water emulsion evaporation to develop injectable bone substitutes incorporated with cells. The spheres were approximately 1.2mm in diameter and had a shell with a thickness in the range of 50-150microm. The hollow in the spheres was presumed to be formed by CO(2) gas generated by the decomposition of vaterite used as a starting material. An open channel approximately 800microm in diameter was formed in the spheres by chemical etching utilizing the rapid dissolution of poly(lactic acid) at the thin portion of the shell. Cells could migrate into the hollow spheres through the open channel and attach to the inner surface.

3T3 Cells↗

PubMed1992

Controlled cisplatin delivery system using poly(D,L-lactic acid).

Cisplatin (CDDP)-containing poly(D,L-lactic acid) microspheres (CDDP-MS) and beads (CDDP-B) with an average molecular weight of the oligomer of 1.2 x 10(4) and 4% CDDP loading were prepared. In Tris buffer, 95% of CDDP disappeared from CDDP-MS within 3 d. In vitro and in vivo, CDDP-B released CDDP for 30-57 d, and for 21-42 d, respectively. The other CDDP-B with an average oligomer molecular weight of 9.6 x 10(3) with 5% lactic acid monomers, that contained 4% CDDP, showed a two-phase CDDP release pattern and CDDP disappeared within 41 d in vitro, and within 21 d in vivo. Histologically, tissue necrosis surrounding the CDDP-B was not severe.

Animals↗

PubMed1996

Epidermal and dermal effects of topical lactic acid.

BACKGROUND: Many alpha-hydroxy acid products, containing low- or high-acid concentrations, are being used. It is not known whether different products perform differently or whether they modulate changes in both the epidermis and dermis. OBJECTIVE: The purpose was to examine whether treatment with 5% and 12% lactic acid produces different cosmetic results and produces changes in the epidermis and dermis. METHODS: Test participants applied either 5% or 12% lactic acid twice a day for 3 months. Changes in skin smoothness and texture, the depth and number of lines and wrinkles, and epidermal and dermal firmness and thickness were determined. RESULTS: Treatment with 12% lactic acid resulted in increased epidermal and dermal firmness and thickness and clinical improvement in skin smoothness and in the appearance of lines and wrinkles. No dermal changes were observed after treatment with 5% lactic acid; however, similar clinical and epidermal changes were noted. CONCLUSION: The results demonstrate that cosmetic benefits from the use of alpha-hydroxy acids are caused by modification of the skin surface, the epidermis and the dermis. Although 5% lactic acid modulates surface and epidermal changes, 12% lactic acid influences both the epidermis and the dermis.

Administration, Cutaneous↗

PubMed1994

Fermentation of fructans by epiphytic lactic acid bacteria.

A total of 712 strains of lactic acid bacteria isolated from forage grasses were studied for their ability to ferment fructans of phlein- as well as inulin-type. Only 16 strains utilized phlein and eight of these also fermented inulin. They were identified as Lactobacillus paracasei subsp. paracasei, Lact. plantarum, Lact. brevis and Pediococcus pentosaceus. In the species Lact. paracasei subsp. paracasei, all strains gave positive results, whereas the other positive strains possessed unique properties within their own species. In all but two cases (strains of the species Lact. plantarum), the phlein was more intensively fermented than the inulin, as indicated by a lower pH and a higher lactic acid concentration. On the basis of the outcome of this study it seems worthwhile to inoculate grasses of low sugar content before ensiling with an active strain that can ferment fructans.

Fermentation↗

PubMed1993

Isolation and characterization of the substance isolated from Streptosporangium species which inhibits lactic acid production by oral bacteria.

1. The tentatively named MLI, which inhibits lactic acid production in mutants streptococci, was isolated from Streptosporangium species and purified by solvent extraction followed by chromatography, and then powdered. 2. MLI greatly inhibited pH-decline and lactic acid production in glucose-containing reaction mixture by mutans streptococci or Lactobacillus species. 3. These inhibitory mechanisms were not caused by an anti-bacterial effect, since the addition of a sufficient concentration of MLI to inhibit lactic acid production to the culture, recovery of cells in culture was not affected, excluding L. acidophilus. 4. MLI directly affected lactate dehydrogenase (LDH) activity. 5. These results indicate that MLI may represent a new anti-cariogenic substance.

Biological Factors↗

PubMed2002

Discovering lactic acid bacteria by genomics.

This review summarizes a collection of lactic acid bacteria that are now undergoing genomic sequencing and analysis. Summaries are presented on twenty different species, with each overview discussing the organisms fundamental and practical significance, environmental habitat, and its role in fermentation, bioprocessing, or probiotics. For those projects where genome sequence data were available by March 2002, summaries include a listing of key statistics and interesting genomic features. These efforts will revolutionize our molecular view of Gram-positive bacteria, as up to 15 genomes from the low GC content lactic acid bacteria are expected to be available in the public domain by the end of 2003. Our collective view of the lactic acid bacteria will be fundamentally changed as we rediscover the relationships and capabilities of these organisms through genomics.

Bifidobacterium↗

PubMed1999

Novel polymer-polymer conjugates for recovery of lactic acid by aqueous two-phase extraction.

A new family of polymer conjugates is proposed to overcome constraints in the applicability of aqueous two-phase systems for the recovery of lactic acid. Polyethylene glycol-polyethylenimine (PEI) conjugates and ethylene oxide propylene oxide-PEI (EOPO-PEI) conjugates were synthesized. Aqueous two-phase systems were generated when the conjugates were mixed with fractionated dextran or crude hydrolyzed starch. With 2% phosphate buffer in the systems, phase diagrams with critical points of 3.9% EOPO-PEI-3.8% dextran (DEX) and 3.5% EOPO-PEI-7.9% crude starch were obtained. The phase separation temperature of 10% EOPO-PEI solutions titrated with lactic acid to pH 6 was 35 degrees C at 5% phosphate, and increased linearly to 63 degrees C at 2% phosphate. Lactic acid partitioned to the top conjugate-rich phase of the new aqueous two-phase systems. In particular, the lactic acid partition coefficient was 2.1 in 10% EOPO-PEI-8% DEX systems containing 2% phosphate. In the same systems, the partitioning of the lactic acid bacterium, Lactococcus lactis subsp. lactis, was 0.45. The partitioning of propionic, succinic, and citric acids was also determined in the new aqueous two-phase systems.

Biotechnology↗

PubMedDate not supplied

Bacteriophage defence systems in lactic acid bacteria.

The study of the interactions between lactic acid bacteria and their bacteriophages has been a vibrant and rewarding research activity for a considerable number of years. In the more recent past, the application of molecular genetics for the analysis of phage-host relationships has contributed enormously to the unravelling of specific events which dictate insensitivity to bacteriophage infection and has revealed that while they are complex and intricate in nature, they are also extremely effective. In addition, the strategy has laid solid foundations for the construction of phage resistant strains for use in commercial applications and has provided a sound basis for continued investigations into existing, naturally-derived and novel, genetically-engineered defence systems. Of course, it has also become clear that phage particles are highly dynamic in their response to those defence systems which they do encounter and that they can readily adapt to them as a consequence of their genetic flexibility and plasticity. This paper reviews the exciting developments that have been described in the literature regarding the study of phage-host interactions in lactic acid bacteria and the innovative approaches that can be taken to exploit this basic information for curtailing phage infection.

Animals↗

PubMed2004

Fluorescent in situ hybridization analysis of open lactic acid fermentation of kitchen refuse using rRNA-targeted oligonucleotide probes.

Reproducible amounts of lactic acid accumulate in minced kitchen refuse under open conditions with intermittent pH neutralization [Sakai et al., Food Sci. Technol. Res., 6, 140 (2000)]. Here, we showed that such pH-controlled open fermentation of kitchen refuse reproducibly resulted a selective proliferation of a major lactic acid bacterial (LAB) species. In one experiment, the predominant microorganisms isolated during the early phase (6 h) were Gammaproteobacteria. In contrast, those that predominated during the late phase (48 h) were always Lactobacillus plantarum in three independent experiments. To further quantify the microbial community within open lactic acid fermentation, we performed fluorescent in situ hybridization (FISH) analysis targeting 16S (23S) rRNA. We designed two new group-specific DNA probes: LAC722(L) was active for most LAB including the genera Lactobacillus, Pediococcus, Leuconostoc and Weisella, whereas Lplan477 was specific for L. plantarum and its related species. We then optimized sample preparation using lysozyme and hybridization conditions including temperature, as well as the formamide concentration and the salt concentration in the washing buffer. We succeeded in quantification of microorganisms in semi-solid, complex biological materials such as minced kitchen refuse by taking color microphotographs in modified RGB balance on pre-coated slides. FISH analysis of the fermentation of kitchen refuse indicated that control of the pH swing leads to domination by the LAB population in minced kitchen refuse under open conditions. We also confirmed that L. plantarum, which generates lactic acid in high quantities but with low optical activity, became the dominant microorganism in kitchen refuse during the late phase of open fermentation.

Journal Article↗

PubMed2003

Marinilactibacillus psychrotolerans gen. nov., sp. nov., a halophilic and alkaliphilic marine lactic acid bacterium isolated from marine organisms in temperate and subtropical areas of Japan.

A novel marine lactic acid rod bacterium has been described for eight strains isolated from living and decomposing marine organisms collected from temperate and subtropical areas of Japan. The isolates were Gram-positive, catalase-negative, non-sporulating and motile with peritrichous flagella. They were slightly halophilic, highly halotolerant and alkaliphilic; the optimum NaCl concentration for growth was 2.0-3.75% (w/v) with a range from 0 to 17.0-20.5% (depending on the strain); the optimum pH was between 8.0 and 9.5 with a range from 6.0 to 10.0. They were psychrotolerant, growing well at -1.8 degrees C with a maximum at 40-45 degrees C and the optimum at 37-40 degrees C. Lactate yields were 87-100% per consumed glucose; the residual products were formate, acetate and ethanol with a molar ratio of approximately 2 : 1 : 1. The product composition was markedly affected by the pH of fermentation medium; at higher pH, the yield of lactate decreased (60-65% at pH 9.0) and that of other products increased conversely. The cell-wall peptidoglycan type was type A4beta, Orn-D-Glu, whereas that of the genus Alkalibacterium, the phylogenetically closest lactic acid bacterium, was type A4beta, Orn-D-Asp. The major cellular fatty acids were C16 : 0, C16 : 1delta9, C18 : 0 and C18 : 1delta9 (oleic acid). The G + C content of the DNA was 34.6-36.2 mol%. The eight isolates were phenotypically homogeneous and formed a single genomic species. The 16S rRNA gene sequence analysis indicated that the isolates constituted an independent phylogenetic lineage within the radiation of lactic acid bacteria with 96.2% similarity to the genus Alkalibacterium. The secondary structure and the nucleotide sequence of the V6 region of the 16S rRNA were characteristic of the organism among other related lactic acid genera. On the bases of phenotypic and phylogenetic distinctness, the organism was proposed to belong to a new genus and species, Marinilactibacillus psychrotolerans gen. nov., sp. nov. The type strain, M13-2(T) (G + C = 36.2 mol%), has been deposited in the IAM, NBRC, NCIMB and NRIC culture collections as IAM 14980(T), NBRC 100002(T), NCIMB 13873(T) and NRIC 0510(T), respectively.

Animals↗

PubMed2004

Effect of single or sequential hot water and lactic acid decontamination treatments on the survival and growth of listeria monocytogenes and spoilage microflora during aerobic storage of fresh beef at 4, 10, and 25 degrees C.

The survival and growth of Listeria monocytogenes and spoilage microflora during storage of fresh beef subjected to different decontamination treatments was studied. Fresh beef inoculated with a five-strain mixture of L. monocytogenes (5.18 log CFU/cm2) was left untreated (control) or was immersed (30 s) in hot water (HW; 75 degrees C), 2% lactic acid (LA; 55 degrees C), hot water followed by lactic acid (HW-LA), or lactic acid followed by hot water (LA-HW) and then stored aerobically at 4, 10, and 25 degrees C for 25, 17, and 5 days, respectively. Initial populations of L. monocytogenes were reduced by 0.82 (HW), 1.43 (LA), 2.73 (HW-LA), and 2.68 (LA-HW) log CFU/cm2. During storage, the pathogen grew at higher rates in HW than in control samples at all storage temperatures. Acid decontamination treatments (LA. HW-LA, and LA-HW) resulted in a weaker inhibition of L. monocytogenes (P < 0.05) at 25 degrees C than at 4 and 10 degrees C. In general, the order of effectiveness of treatments was HW-LA > LA > LA-HW > HW > control at all storage temperatures tested. In untreated samples, the spoilage microflora was dominated by pseudomonads, while lactic acid bacteria, Enterobacteriaceae, and yeasts remained at lower concentrations during storage. Brochothrix thermosphacta was detected periodically in only a limited number of samples. Although decontamination with HW did not affect the above spoilage microbial profile, acid treatments shifted the predominant microflora in the direction of yeasts and gram-positive bacteria (lactic acid bacteria). Overall, the results of the present study indicate that decontamination with LA and combinations of LA and HW could limit growth of L. monocytogenes and inhibit pseudomonads, which are the main spoilage bacteria of fresh beef stored under aerobic conditions. However, to optimize the efficacy of such treatments, they must be applied in the appropriate sequence and followed by effective temperature control.

Animals↗

PubMed2001

Lactic acid sprays reduce bacterial pathogens on cold beef carcass surfaces and in subsequently produced ground beef.

Organic acids have been shown to be effective in reducing the presence of pathogenic bacteria on hot beef carcass surfaces; however, application for decontaminating chilled carcasses has not been fully evaluated. In this study, a postchill, 30-s lactic acid spray (500 ml of 4% L-lactic acid, 55 degrees C) was applied onto outside rounds that had been contaminated with Escherichia coli O157:H7 and Salmonella Typhimurium, subsequent to prechill hot carcass treatments consisting of water wash alone or water wash followed by a 15-s lactic acid spray (250 ml of 2% L-lactic acid, 55 degrees C). The prechill treatments reduced both pathogens by 3.3 to 3.4 log cycles (water wash alone) to 5.2 log cycles (water wash and lactic acid). In all cases, the postchill acid treatment produced an additional reduction in E. coli O157:H7 of 2.0 to 2.4 log cycles and of 1.6 to 1.9 log cycles for Salmonella Typhimurium. The counts of both pathogens remained significantly lower in ground beef produced from the outside rounds that received prechill and postchill acid spray than from those that received a postchill spray only. These data indicate that organic acid sprays may be successfully applied for pathogen reduction in beef carcass processing after the cooler, especially when combined with prechill treatments.

Aerosols↗

PubMed1999

Continuous production of L(+)-lactic acid by Lactobacillus casei in two-stage systems.

A two-stage two-stream chemostat system and a two-stage two-stream immobilized upflow packed-bed reactor system were used for the study of lactic acid production by Lactobacillus casei subsp casei. A mixing ratio of D12/D2 = 0.5 (D = dilution rate) resulted in optimum production, making it possible to generate continuously a broth with high lactic acid concentration (48 g l-1) and with a lowered overall content of initial yeast extract (5 g l-1), half the concentration supplied in the one-step process. In the two-stage chemostat system, with the first stage at pH 5.5 and 37 degrees C and a second stage at pH 6.0, a temperature change from 40 degrees C to 45 degrees C in the second stage resulted in a 100% substrate consumption at an overall dilution rate of 0.05 h-1. To increase the cell mass in the system, an adhesive strain of L. casei was used to inoculate two packed-bed reactors, which operated with two mixed feedstock streams at the optimal conditions found above. Lactic acid fermentation started after a lag period of cell growth over foam glass particles. No significant amount of free cells, compared with those adhering to the glass foam, was observed during continuous lactic acid production. The extreme values, 57.5 g l-1 for lactic acid concentration and 9.72 g l-1 h-1 for the volumetric productivity, in upflow packed-bed reactors were higher than those obtained for free cells (48 g l-1 and 2.42 g l-1 h-1) respectively and the highest overall L(+)-lactic acid purity (96.8%) was obtained in the two-chemostat system as compared with the immobilized-cell reactors (93%).

Biomass↗

PubMed1979

Plasma glucose and lactic acid alterations in response to a stressful exam.

Changes in lactic acid and plasma glucose levels as a function of examination stress were measured using a 'pinprick' blood sampling method. Blood samples were obtained from 12 subjects at each of four times, one week prior to the exam, within 15 min pre-exam, within 15 min post-exam, and three weeks after the exam. Glucose was significantly elevated pre-exam over control times and decreased significantly from before to after the exam. Lactic acid was significantly elevated pre-exam over control times and increased significantly before to after the exam. It is suggested that changes in the levels of these metabolites in the blood are indicative of stress levels. Self-ratings of 'nervousness' were not significantly correlated with either pre-exam glucose or pre-exam lactic acid.

Adult↗

PubMed1993

[The effect of different lactic acid isomers in the colon of rats].

Depending on quantity and/or quality, the presence of lactic acid in the colonic lumen may be associated with metabolic damage of the colon. The influence exerted on the rat colon by the different isomers and racemic of the lactic acid, used at two extreme dilutions (20 and 100 mEq/l), has been the subject of study in this paper. The modifications on pH, water and electrolytes are associated with the absorptive/secretory action of the colonic wall. In addition, a study has been made on the influence of lactic acid on the colonic mucus and albumin permeation. Histopathologic studies of the caecum and left colon have been performed. There is a different colonic wall behaviour for each of the different isomers of the lactic and its racemic; a larger absorption of water, Na+ and Cl- for the D (-) isomer at a low concentration; its behaviour is completely opposite at high concentration. The final pH is higher when the D (-) isomer takes part; comparing the different isomers, there are small variations as far as albumin permeation is concerned. At high concentration there is a decline in Cl- absorption. The high percentage of erosions that take place especially in the caecum, where L (+) isomer can be found at high concentration, it is remarkable. The present observations suggest that the presence of lactic acid in (the) ulcerative colitis deserves great attention, especially in about the quantity and quality in which the acid can be found.

Animals↗

PubMed2002

The effect of sodium acetate on the growth yield, the production of L- and D-lactic acid, and the activity of some enzymes of the glycolytic pathway of Lactobacillus sakei NRIC 1071(T) and Lactobacillus plantarum NRIC 1067(T).

The effect of sodium acetate was studied on the change of the growth yield, the production of L- and D-lactic acid, and the activity of lactate dehydrogenases (LDHs; L-lactate dehydrogenase [EC 1.1.1.27, L-LDH] plus D-lactate dehydrogenase [EC 1.1.1.28, D-LDH]), fructose-1, 6-bisphosphate aldolase [EC 4.1.2.13, FBP-aldolase], and phosphofructokinase [EC 2.7.1.11, PFK] of Lactobacillus sakei NRIC 1071(T) and Lactobacillus plantarum NRIC 1067(T). The growth yield of L. sakei NRIC 1071(T) was increased 1.6 times in the presence of sodium acetate compared with its absence. The activity of LDHs in L. sakei NRIC 1071(T) and L. plantarum NRIC 1067(T) was retained longer under the addition of sodium acetate in the reaction mixture. As a result, these strains produced much more lactic acid in the presence of sodium acetate compared with its absence. Furthermore, the activity of L-LDH in L. sakei NRIC 1071(T) cultivated in the presence of sodium acetate increased three times or more compared with the activity of the cells cultivated in its absence. Consequently, the type of stereoisomers of lactic acid produced by L. sakei shifted from the DL-type to the L-type because the ratio of L-lactic acid to D-lactic acid produced became larger with the addition of sodium acetate to culture media. This phenomenon was not observed in L. plantarum NRIC 1067(T). Further, the participation of lactate racemase is discussed from the viewpoint of the production of D-lactic acid by L. sakei.

Fructose-Bisphosphatase↗

PubMed1997

Purification of bacteriocins of lactic acid bacteria: problems and pointers.

Bacteriocins of lactic acid bacteria have been widely studied in recent years. However, there are relatively few studies that describes their biochemical structure. This study may be due to the many challenges associated with the purification of these antimicrobial peptides. This review focuses on the purification procedures used with bacteriocins of lactic acid bacteria and conveys some of the problems associated with this process as well as some of the lessons learned. An improvement in the efficiency of the purification process should contribute significantly to research at the understanding of the biochemical nature of bacteriocins.

Bacteriocins↗