Abstract:
To screen out lactic acid bacteria strains with high
β-glucosidase and tannase productivity, the
p-NPG method was initially employed to select 34 robustly growing lactic acid bacteria strains with strong
β-glucosidase production capabilities from 70 lactic acid bacteria strains sourced from fermented foods. Building upon this, the danthronine method was used for further screening, yielding two strains with high tannase productivity, designated as GD03 and GD05. These two strains were subsequently domesticated and cultured in jujube usinga concentration gradient method. The results indicated that the domesticated strains GD03 and GD05 adapted well to the jujube juice environment. Both the intracellular and extracellular
β-glucosidase activities, as well as the extracellular tannase activities of these strains were significantly increased after fermentation compared with pre-fermentation levels (
P < 0.05). Specifically, the intracellular
β-glucosidase enzyme activity increased 7-fold, while their extracellular
β-glucosidase enzyme activities both increased by 22-fold. The extracellular tannase enzyme activities increased by 4-fold and 6-fold for GD03 and GD05, respectively. Additionally, the soluble dietary fiber content increased by 1-fold and 0.5-fold, and the tannin content decreased by 50.69% and 55.40%, for GD03 and GD05, respectively. These findings provide new insights into screening for lactic acid bacteria with high-yielding
β-glucosidase and tannase productivity and lay a theoretical foundation for the application of high-enzyme-yielding
Lactobacillus in plant-based fermented foods.