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 b-glucosidase enzyme from wine Lactobacillus plantarum and from a commercial strain of Oenococcus oeni. Methods and Results: The coding region of the putative b-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. oeni b-glucosidase gene. The protein sequence deduced from the isolated genes has a calculated molecular mass of 61Æ19 kDa. Furthermore, the expression of the b-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 b-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. plantarum b-glucosidase gene may be useful to explain the differences found in b-glucosidase activity reported in wines by several authors.