Investgation Of Beta-Glucosidase And Malolactic Fermentation Potential From Wine Lactobacillus Plantarum

There is an important part of the aroma compounds are tasteless sugar complexes,namely glucosides present in wine, which can be released by the hydrolysis of glucoside aroma active substances, and significantly improve the quality of wine aroma. β-Glucosidase is a key enzyme in the enzymatic release of these bound monoterpenols from their glucosidic precursor. As the next generation of malolactic starter culture, Lactobacillus plantarum has high β-glucosidase activity, even higher than that in Oenococcus oeni. In the present study, theβ-glucosidase activity and enzymatic property of four L. plantarum strains isolated from wine were analyzed; the gene of β-glucosidase from four L. plantarum strains were cloned and analysed by bioinformatics; Finally, the MFL potential of L. plantarum were evaluated. The main results are as following:(1) The growth trend of strains in MRS culture medium was in the same with the improved MRS culture medium, but improved MRS culture medium could significantly improve the activity of β-glucosidase. Significant difference was found in all strains of enzyme activity, the highest β-glucosidase activity of four strains was strain XJ-25; Strain XJ-14 was behind; The strain XJA-2 and CS-1 showed low enzyme activity. The optimum temperature of β-glucosidase is 45 ℃, and its not high temperature resistant; The optimum pH of β-glucosidase is 5.0, but the pH in the range of 3 to 7 has little influence on enzyme activity;the effect of ethanol for β-glucosidase enzymes showed obvious inhibitory.(2) β-Glucosidase genes were cloned from XJ-14, XJ-25, XJA-2 and CS-1. Deduced amino acid sequences of sequenced genes showed high homology(above 99%) to the reported wine L. plantarum Lp90. Protein bioinformatics prediction results showed thatβ-glucosidase from four L. plantarum were weaker hydrophobic, it could be soluble protein;the prediction of signal peptide showed its not a secretory protein.(3) Four L. plantarum strains XJ-14, XJ-25, XJA-2 and CS-1 isolated from wine showed good potential of deacidification and MLF, the fermentation for 15 days declined acid about1.1 g/L, but did not complete MLF. Starting MLF by using L. plantarum XJ-25 could released more alcohol ester aroma substances which enhance the fruit and floral characteristics of the wine. It could be more advantageous to improve the quality of wine aroma relative to other strains. Therefore, L. plantarum XJ-25 has the potential of development for commercial starter cultures.