Influence of tannase from Serratia marcescens strain IMBL5 on enhancing antioxidant properties of green tea

Abstract The present study focused on the isolation, optimization and characterization and potential application of tannase from gut bacterium. Microbes were isolated from the gut of dung beetle Onthophagus babirussa IMBL which is an unexplored source of novel enzymes. Serratia marcescens strain IMBL5 was found to be the most potent tannase producer out of 36 isolates. The adjusted process parameters for maximum tannase yield were pH 4.5 at 45 °C and 96 h incubation. The tannase production was increased 4.46 fold to 120.13 U/mL, by varying the concentration of media components using Response surface methodology. The molecular weight of purified tannase was resolved at ∼40 kDa through SDS-PAGE analysis. Several functional groups including carboxyl, hydroxyl and amide groups were detected in FT-IR analysis whilst the occurrence of epicatechin gallate peaks detected from HPLC chromatogram signifying the tannin degradation. Tannase also potentially induce the antioxidant properties of green tea extract which was determined through in-vitro analysis. There was no hemolytic activity exhibited in hemolysis assay using human red blood cells which corroborated that tannase derived from S. marcescens strain IMBL5 might be a safe and promising agent in food industry.