Screening of rice proteolytic protease-producing strain for preparing rice oligopeptides

Abstract:

[Objective] To isolate, screen and identify strains with rice protein degradation activity and their key proteases, so as to provide ideal enzymes for the preparation of rice oligopeptides. [Methods] Strains with the ability to degrade rice protein were screened from the soil near grain warehouse by "hydrolysis circle", and identified by 16S rRNA analysis. Single factor experiment was done to obtain optimal nitrogen source. Enzymes were then characterized. The yield of rice oligopeptides was detected by HPLC, and the preparation conditions were further optimized. [Results] The best strain was identified as Serratia sp. JWG-D15. The highest protease SoPRO production was achieved by using rice protein as nitrogen source with optimal temperature at 40℃ and optimal pH of 8.0. The highest yield of rice oligopeptides was 72.38%, with 20 U/mg protease SoPRO, and 40 mg/mL rice protein at 40℃ for 4 hours. [Conclusion] Strain JWG-D15 had highest protease SoPRO production by using rice protein as nitrogen source, and the yield of rice oligopeptides was the highest. This study enriched enzyme sources for the preparation of rice oligopeptide.

Key words:rice protein;oligopeptide;protease;Serratia sp.