Oxygen utilization by Lactobacillus plantarum

Cell-free extracts of Lactobacillus plantarum contain non-proteinaceous compounds which mimic superoxide dismutase activity. Using the test system in which O ₂ ^– is generated by xanthine oxidase, superoxide dismutase activity is found in cell-free extracts, where proteins are removed by precipitation. This activity is strongly decreased after dialysis of cell-free extracts. Superoxide dismutase activity was also investigated by means of pulse radiolysis. Cell-free extracts of Escherichia coli were also investigated as a comparison, which were known to contain superoxide dismutase. With cell-free extracts of both L. plantarum and E. coli the decay of O ₂ ^– was markedly increased. However, the type of reaction of the O ₂ ^– decay was of first order in the presence of E. coli extracts due to superoxide dismutase(s), and of second order in the presence of L. plantarum extracts, indicating that O ₂ ^– elimination is not an enzymic reaction. Mn²⁺ phosphate(s) might be responsible for the observed elimination of O ₂ ^– . The production of O ₂ ^– is not detectable during NADH-, lactate- or pyruvate oxidase reactions in L. plantarum extracts.     

Lactobacillus plantarum 299v Prevents Caspase-Dependent Apoptosis In Vitro

Selective microbes used as probiotics can enhance epithelial cell protection. We have previously shown that a Lactobacillus plantarum strain 299v (Lp299v) has the ability to induce mucin genes. In the current study, we utilized a cytokine model of inflammation in cell culture to study the modulation of apoptosis by this probiotic. HT-29 cells were pre-incubated with the Lp299v or L. plantarum strain adh- (Lpadh-), a non-adherent derivative of Lp299v. Cells were challenged with a mixture of cytokines (TNF-α, IFN-γ, and IL-1a) to imitate conditions of inflammation. To assess for cell death, we evaluated TUNEL, multi-caspase, and caspase-3 and caspase-7 activity assays. There was a marked decrease in apoptosis as measured by TUNEL⁺ cells in samples pre-treated with Lp299v (18.7 ± 4.1%, p < 0.01) and Lpadh- (16.6 ± 3.2%, p < 0.05) prior to cytokine exposure when compared to cells (43.6 ± 6.2%) exposed to the cytokine mixture. Lp299v pre-incubation with HT-29 cells reduced caspase⁺ cells in the multi-caspase activity assay (3.6 ± 0.6%, p < 0.05) compared to cells exposed to cytokines (68.9 ± 5.1%) whereas Lpadh- did not (46.8 ± 17.5%, p > 0.05). Similarly, caspase-3, caspase-7 activity was also reduced by Lp299v. Selected probiotics may confer an exogenous protective effect at the mucosal–luminal interface for intestinal epithelial cells via alteration of caspase-dependent apoptotic pathways.     

Anaerobic l-lactate degradation by Lactobacillus plantarum

Abstract Lactobacillus plantarum strains used as silage inoculants were investigated for their ability to metabolize lactic acid anaerobically after prolonged incubation (7–30 days) when glucose was absent from the medium. When citrate was present in the medium together with glucose during the initial fermentation, the lactic acid produced was degraded. Citrate was concomitantly degraded, resulting in accumulation of formic, acetic and succinic acids along with CO₂. The anaerobic degradation was confirmed by the use of l ¹⁴C(U) labelled lactate. The existence of pyruvate formate lyase in L. plantarum was indicated by using ¹⁴C-labelled pyruvate and HPLC identification of end-products. The 1-¹⁴C-carboxylic acid group of pyruvate was converted to formic acid, and the 3-¹⁴C was found in acetic acid. The key enzyme(s) in this metabolic pathway appears to require anaerobic conditions and induction by citrate.     

植物乳杆菌细菌素的研究与应用

植物乳杆菌细菌素不仅种类多,产生菌在发酵过程中还可产生良好的保健功效,因此成为研究的热点。本文对植物乳杆菌细菌素的种类、分子结构、抑菌机制及遗传控制做了较为详尽的介绍,并简要介绍了植物乳杆菌细菌素在食品、医药、饲料中的应用,为进一步研究植物乳杆菌细菌素提供了参考。     

Growth and Survival of Genetically Manipulated Lactobacillus plantarum in Silage

The growth and persistence of two genetically manipulated forms of Lactobacillus plantarum NCDO (National Collection of Dairy Organisms) 1193 have been monitored in grass silage. Both recombinants contained pSA3, a shuttle vector for gram-positive organisms that encodes erythromycin resistance. In one of the recombinants, pSA3 was integrated onto the chromosome, whereas in the other, a pSA3 derivative designated pM25, which contains a Clostridium thermocellum cellulase gene cloned into pSA3, was maintained as an extrachromosomal element. This extrachromosomal element is a plasmid. Rifampin-resistant mutants were selected for the recombinants and the parent strain. When applied to minisilos at a rate of 10⁶ CFU/g of grass, both the recombinants and the parent strain proliferated to dominate the epiphytic microflora and induced an increase in the decline in pH compared with that of the noninoculated silos. The presence of extra genetic material did not appear to disadvantage the bacterium in comparison with the parent strain. The selective recovery of both strains by using rifampin and erythromycin was confirmed by Southern hybridization. Interestingly, the free plasmid (pM25) appeared more stable in silage than was expected from studies in MRS broth. The plasmid was retained by 85% of the rifampin-resistant L. plantarum colonies isolated from a day 30 silo. These data answer an important question by showing that genetically manipulated recombinants of L. plantarum can proliferate and compete with epiphytic lactic acid bacteria in silage.     

Identification of Antioxidants Produced by Lactobacillus plantarum

We identified two compounds that demonstrated 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity from cultures of Lactobacillus plantarum. Spectroscopic analyses proved these compounds to be L-3-(4-hydroxyphenyl) lactic acid (HPLA) and L-indole-3-lactic acid (ILA). The respective EC₅₀ values for HPLA and ILA were 36.6 ± 4.3 mM and 13.4 ± 1.0 mM.     

In vitro growth inhibition of Helicobacter pylori by lactobacilli belonging to the Lactobacillus plantarum group

AIMS: The aim of this study was to test and locate the in vitro anti-Helicobacter activity of seven Lactobacillus strains belonging to Lactobacillus plantarum group. METHODS AND RESULTS: Growth inhibition of H. pylori was tested using a well-plate assay. Of the strains displaying the strongest growth inhibition, a L. plantarum isolated from sauerkraut (MLBPL1) was chosen for further studies. The detected anti-Helicobacter activity of MLBPL1 was mainly associated with cell wall, and to a minor extent with the culture supernatant. The active component, which was determined to be between 3 and 10 kDa in size, retained its activity after 10 min treatment at 100 degrees C. The activity was present when MLBPL1 was cultivated in rich laboratory cultivation medium MRS and in different food matrices. CONCLUSIONS: The strains belonging to L. plantarum group showed anti-Helicobacter activity in vitro. The main activity seemed to be associated with cell wall rather than culture supernatant or intracellular fraction. SIGNIFICANCE AND IMPACT OF THE STUDY: In view of the rapid spread of resistant H. pylori strains caused by antibiotic therapy, addition of a fermented food containing L. plantarum to the conventional antibiotic treatment of Helicobacter infection could establish a potential complementary means to suppress the infection.     

Growth of Lactobacillus plantarum in media containing hydrolysates of fish viscera

AIMS: To compare growth of Lactobacillus plantarum on media containing hydrolysates (peptones) from cod viscera with growth on commercial media. METHODS AND RESULTS: Growth of Lact. plantarum on various fish peptones and commercial peptones/extracts was evaluated using both a Bioscreen apparatus (microtiter plates, no pH control) and fermentors (with pH control). Generally, the performance of the fish peptones was good and only beaten by the performance of yeast extract. Replacement of the 22 g l(-1) complex nitrogen source in standard MRS medium with only 5 g l(-1) fish peptone reduced the biomass yield with only 10%, whereas replacement with a mixture of 2.5 g l(-1) fish peptone and 2.5 g l(-1) yeast extract increased the biomass yield by 10%. CONCLUSIONS: Peptones derived from cod viscera support excellent growth of Lact. plantarum. SIGNIFICANCE AND IMPACT OF THE STUDY: We show that peptones derived from cod viscera are promising constituents of growth media for fastidious food bacteria such as lactobacilli. Media containing these peptones show excellent performance while problems associated with the use of meat-derived peptones (BSE, kosher status) or plant-derived peptones (genetically modified organisms) are avoided.     

Lactobacillus casei and Lactobacillus plantarum initiate catabolism of methionine by transamination

AIMS: To study the ability of Lactobacillus casei and Lact. plantarum strains to convert methonine to cheese flavour compounds. METHODS AND RESULTS: Strains were assayed for methionine aminotransferase and lyase activities, and amino acid decarboxylase activity. About 25% of the strains assayed showed methionine aminotransferase activity. The presence of glucose in the reaction mixture increased conversion of methionine to 4-methylthio-2-ketobutanoate (KMBA) and 4-methylthio-2-hydroxybutanoate (HMBA) in all strains. The methionine aminotransferase activity in Lact. plantarum and Lact. casei showed variable specificity for the amino group acceptors glyoxylate, ketoglutarate, oxaloacetate and pyruvate. None of the strains showed methionine lyase or glutamate and methionine decarboxylase activities. CONCLUSION: The presence of amino acid converting enzymes in lactobacilli is strain specific. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings of this work suggest that lactobacilli can be used as adjuncts for flavour formation in cheese manufacture.     

Oxygen dependent lactate utilization by Lactobacillus plantarum

Lactobacillus plantarum P5 grew aerobically in rich media at the expense of lactate; no growth was observed in the absence of aeration. The oxygen-dependent growth was accompanied by the conversion of lactate to acetate which accumulated in the growth medium. Utilization of oxygen with lactate as substrate was observed in buffered suspensions of washed whole cells and in cell-free extracts. A pathway which accounts for the generation of adenosine triphosphate during aerobic metabolism of lactate to acetate via pyruvate and acetyl phosphate is proposed. Each of the enzyme activities involved, nicotinamide adenine dinucleotide independent lactic dehydrogenase, nicotinamide adenine dinucleotide dependent lactic dehydrogenase, pyruvate oxidase, acetate kinase and NADH oxidase were demonstrated in cell-free extracts. The production of pyruvate, acetyl phosphate and acetate was demonstrated using cell-free extracts and cofactors for the enzymes of the proposed pathway.Abbreviations MRS Man, Rogosa and Sharpe (1960) medium modified as in Materials and methods - TY Tryptone Yeast Extract broth - OUL Oxygen uptake with lactate as substrate - DCPIP 2,6-Dichlorophenolindophenol - LDH Lactic dehydrogenase     

Competitive Growth of Genetically Marked Malolactic-Deficient Lactobacillus plantarum in Cucumber Fermentations

Procedures were developed for the differential enumeration of an added strain of Lactobacillus plantarum and indigenous lactic acid bacteria (LAB) during the fermentation of brined cucumbers. The added strain was an N,N-nitrosoguanidine-generated mutant that lacked the ability to produce CO₂ from malic acid (MDC^-). The MDC^- phenotype is desirable because CO₂ production from malic acid decarboxylation has been shown to contribute to bloater formation in fermented cucumbers. A basal medium containing malic acid and adjusted to pH 4.0 permitted growth of indigenous LAB (predominantly MDC⁺), but not growth of the added MDC^- culture. Transformation of the MDC^- culture by electroporation with cloning vector pGK12 conferred chloramphenicol resistance, which permitted selective enumeration of this culture. The reversion frequency of the MDC^- mutation was determined by a fluctuation test to be less than 10^-10. The level of retention of plasmid pGK12 was greater than 90% after 10 generations in cucumber juice medium at 32°C. With the procedures developed, we were able to establish the ratio of MDC^- to MDC⁺ LAB that results in malic acid retention in fermentations of filter-sterilized cucumber juice and unsterilized whole cucumbers under specified conditions.     

In vitro importance of probiotic Lactobacillus plantarum related to medical field

Lactobacillus plantarum is a Gram positive lactic acid bacterium commonly found in fermented food and in the gastro intestinal tract and is commonly used in the food industry as a potential starter probiotic. Recently, the consumption of food together with probiotics has tremendously increased. Among the lactic acid bacteria, L. plantarum attracted many researchers because of its wide applications in the medical field with antioxidant, anticancer, anti-inflammatory, antiproliferative, anti-obesity and antidiabetic properties. The present study aimed to investigate the in vitro importance of L. plantarum toward medical applications. Moreover, this report short listed various reports related to the applications of this promising strain. In conclusion, this study would attract the researchers in commercializing this strain toward the welfare of humans related to medical needs.     

Culture conditions of tannase production by Lactobacillus plantarum

Lactobacillus plantarum produced an extracellular tannase after 24 h growth on minimal medium of amino acids containing 2 g tannic acid l^–1. Enzyme production (6 U ml^–1) was optimal at 37 °C and pH 6 with 2 g glucose l^–1 and 7 g tannic acid l^–1 in absence of O₂.     

Energy conservation in malolactic fermentation by Lactobacillus plantarum and Lactobacillus sake

A comparably poor growth medium containing 0.1% yeast extract as sole non-defined constituent was developed which allowed good reproducible growth of lactic acid bacteria. Of seven different strains of lactic acid bacteria tested, only Lactobacillus plantarum and Lactobacillus sake were found to catalyze stoichiometric conversion of l-malate to l-lactate and CO₂ concomitant with growth. The specific growth yield of malate fermentation to lactate at pH 5.0 was 2.0 g and 3.7 g per mol with L. plantarum and L. sake, respectively. Growth in batch cultures depended linearly on the malate concentration provided. Malate was decarboxylated nearly exclusively by the cytoplasmically localized malo-lactic enzyme. No other C₄-dicarboxylic acid-decarboxylating enzyme activity could be detected at significant activity in cell-free extracts. In pH-controlled continuous cultures, L. plantarum grew well with glucose as substrate, but not with malate. Addition of lactate to continuous cultures metabolizing glucose or malate decreased cell yields significantly. These results indicate that malo-lactic fermentation by these bacteria can be coupled with energy conservation, and that membrane energetization and ATP synthesis through this metabolic activity are due to malate uptake and/or lactate excretion rather than to an ion-translocating decarboxylase enzyme.