Screening of Tannase-producing LAB from Phyllanthus emblica Surface and Its Application in Fermented Phyllanthus emblica Juice

In this study, a total of 64 lactic acid bacteria (LAB) strains were isolated from the surface of Phyllanthus emblica. The tannase activity, growth characteristics, tolerance to acid, bile salts, and artificial gastrointestinal fluids, as well as their antibacterial ability of these strains were investigated. Four dominant lactic acid bacterial strains were selected. Through 16S rDNA molecular identification, strains YG-10, YG-8, and YG-6 were identified as Pediococcus pentosaceus, while strain YG-16 was identified as Lactobacillus brevis. Among them, strain YG-10 exhibited a tannase activity of 68.84 U/mL. The survival rates of the strain under pH2.0 and 0.4% bile salt stress were 89.79% and 60.72%, respectively. After 3 hours of incubation in simulated gastric fluid and 4 hours in simulated intestinal fluid, the survival rates were 89.13% and 50.58%, respectively. The strain also showed strong antibacterial activity against Escherichia coli, Staphylococcus aureus and Salmonella. When YG-10 was used to ferment Phyllanthus emblica juice, the degradation rate of tannic acid reached 75.14%, the astringency was weakened, and meanwhile, the characteristic lingering sweetness was retained. This study was the first to screen tannase-producing LAB from the surface of Phyllanthus emblica, which possessed the functions of de-astringency, nutritional enhancement, and probiotic properties. It could provide new resources and technical support for the screening of tannase-producing strains and the development of functional fermented beverages.