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At least 685 records · Page 38Linked to original sources
PubMed2005

A beta-glucosidase gene isolated from wine Lactobacillus plantarum is regulated by abiotic stresses.

AIMS: Little genetic information exists on the ability of wine lactic acid bacteria (LAB) to hydrolyse glycoconjugates during malolactic fermentation. We tried to fill this important gap by characterizing a gene codifying for a putative beta-glucosidase enzyme from wine Lactobacillus plantarum and from a commercial strain of Oenococcus oeni. METHODS AND RESULTS: The coding region of the putative beta-glucosidase gene is 1400 nucleotides long and started with an ATG codon. The gene is widespread among LAB and the highest identity was observed between the nucleotide of L. plantarum, Lactobacillus pentosus, Lactobacillus paraplantarum and O. oenibeta-glucosidase gene. The protein sequence deduced from the isolated genes has a calculated molecular mass of 61.19 kDa. Furthermore, the expression of the beta-glucosidase gene in L. plantarum strain was analysed, under several stress, by reverse transcriptase (RT)-PCR and Northern-blot analysis. The gene was apparently regulated by abiotic stresses such as temperature, ethanol and pH. CONCLUSIONS: The beta-glucosidase gene is widespread among LAB and its expression is probably regulated by a wide range of abiotic stresses. SIGNIFICANCE AND IMPACT OF THE STUDY: The inhibitory effect of temperature and ethanol on the L. plantarumbeta-glucosidase gene may be useful to explain the differences found in beta-glucosidase activity reported in wines by several authors.

Amino Acid Sequence↗
PubMed1995

Inhibitory effect of selected lactic acid bacteria on microflora associated with ready-to-use vegetables.

The addition of selected lactic acid bacteria strains had a remarkable inhibitory effect on the growth dynamics of microflora associated with ready-to-use vegetables, during refrigerated storage. In particular, coliforms and enterococci were strongly reduced or eliminated from the products from the third day of storage. Lactobacillus casei strains proved more effective than pediococci. The use of lactic cultures able to produce bacteriocins and to grow at low temperatures could be a useful tool to preserve fresh vegetables and to ensure their microbiological safety.

Antibiosis↗
PubMed1996

Leuconostoc mesenteroides subsp. mesenteroides FR52 synthesizes two distinct bacteriocins.

Mesenterocin 52, a bacteriocin produced by Leuconostoc mesenteroides subsp. mesenteroides FR52, was purified from producing cells by the adsorption-desorption method, combined with reverse-phase high-performance liquid chromatography. The elution profile revealed the presence of two inhibitory peaks of activity, each displaying different inhibitory spectra. Mesenterocin 52A possessed a broad inhibitory spectrum, including anti-Listeria activity, while Mesenterocin 52B was only active against Leuconostoc spp. The amino acid sequence and M(r) of Mesenterocin 52A appeared identical to the previously described Mesentericin Y105. In contrast, Mesenterocin 52B possessed a M(r) of 3446 Da, corresponding to 32 amino acids and a sequence that shared no homology with known bacteriocins: NH2-KGVLGWLSMASSALTGPQQPNSPWLAKIKNHK.

Amino Acid Sequence↗
PubMed1998

A system for heterologous expression of bacteriocins in Lactobacillus sake.

A system for efficient heterologous expression of class II bacteriocins is described that is based on introducing two plasmids in a bacteriocin-negative Lactobacillus sake strain. The first plasmid (pSAK20) contains the genes necessary for transcriptional activation of the Sakacin A promoter as well as export and processing of bacteriocin precursors. The second plasmid (a pLPV111 derivative) contains the structural and immunity genes for the bacteriocin of interest fused to the sakacin A promoter. Using this system, various bacteriocins were produced at levels equal to or higher than those obtained with the corresponding wild-type producer strains.

Bacteriocins↗
PubMed2002

Monitoring the identity of bacteria using their intrinsic fluorescence.

Three different fluorescence spectra were recorded following excitation at 250 nm (aromatic amino acids+nucleic acids), 270 nm (tryptophan residues) and 316 nm (NADH) for 25 strains of bacteria in dilute suspensions. Evaluation of the spectra using principal component analysis and hierarchical clustering showed a good reproducibility from culture to culture and a good discrimination of the bacteria. Applying the method of Mahalanobis distances to the spectra of lactobacilli species recorded following excitation at 250 nm, a good classification was observed for 100% and 81% of calibration and validation groups, respectively. The developed method allows the discrimination and identification of the investigated bacteria at the genus, species and strain levels.

Bacteria↗
PubMed2006

Histamine, histidine, and growth-phase mediated regulation of the histidine decarboxylase gene in lactic acid bacteria isolated from wine.

Fermented foods are frequently contaminated by histamine that is generated by microorganisms with histidine decarboxylase activity. The ingestion of large amounts of histamine can cause serious toxicological problems in humans. A study of the effects of histamine, histidine, and growth phase on histamine production by lactic acid bacteria isolated from wine is reported here. With northern blots and specific activity analysis, we observed that histidine induces the expression of the histidine decarboxylase gene (hdc) and that histamine causes a decrease in the expression of this gene. The expression of hdc is also mediated by the bacterial growth phase. Histidine and histamine do not affect histidine decarboxylase activity, whereas pyridoxal 5'-phosphate does. Data on histamine-producing lactic acid bacteria isolated from wine should contribute to the prevention of histamine formation during winemaking and storage.

Gene Expression Regulation, Enzymologic↗
PubMed1980

Method for the lysis of Gram-positive, asporogenous bacteria with lysozyme.

A method developed for the lysis of oral streptococci that employed the action of lysozyme suspended in dilute tris(hydroxymethyl)aminomethane-hydrochloride buffer containing polyethylene glycol has been adapted for use with lactobacilli, actinomycetes, propionibacteria, and pediococci. Most of the cellular deoxyribonucleic acid was liberated from many strains of bacteria usually thought to be lysozyme resistant. The major observations were as follows: (i) supplementation of the growth medium with L-threonine, L-lysine, or both frequently produced cells that were more susceptible to lysis by lysozyme; (ii) glucose-containing media produced cells that were more easily lysed than those from cultures grown on other substrates; (iii) polyethylene glycol not only served as an osmotic stabilizer, it also enhanced the extent of lysis; and (iv) dilute tris(hydroxymethyl)aminomethane buffer was superior to the buffer systems most commonly employed in published muramidase-based lysis techniques. Stationary-phase cells of Lactobacillus casei and Streptococcus mutans were more easily lysed than those isolated from log-phase cultures. The method as detailed in this report should be generally applicable for the lysis of gram-positive, asporogenous bacteria.

Actinomyces↗
PubMed1994

Characterization of the Lactobacillus helveticus CNRZ32 pepC gene.

Sequence analysis of the aminopeptidase C gene (pepC) from Lactobacillus helveticus CNRZ32 identified a 1,332-nucleotide open reading frame coding for a polypeptide with motifs characteristic of cysteine proteinases. Homology to the pepC gene appears to be widely distributed among lactic acid bacteria.

Amino Acid Sequence↗