产大米蛋白水解酶的菌株筛选、酶学性质及制备大米寡肽

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

摘要:

[目的] 旨在分离、筛选并鉴定具有大米蛋白降解作用的菌株及其关键蛋白酶，为高效制备大米寡肽提供制备酶及最优制备条件。[方法] 以"水解圈"为评价指标，从粮食仓库附近土壤筛选获得具有降解大米蛋白能力的菌株；通过16S rRNA序列分析确定菌株归属；利用单因素实验获得最佳氮源并初步分析酶学性质；利用HPLC检测寡肽得率，并对制备条件进一步优化。[结果] 经鉴定具有大米蛋白降解作用的菌株为沙雷氏菌（Serratia sp.JWG-D15），以大米蛋白为氮源培养菌株JWG-D15，蛋白酶SoPRO产量最高，其最适温度40℃，最适pH 8.0；在加酶量20 U/mg，大米蛋白浓度40 mg/mL，40℃，4 h条件下寡肽得率最高72.38%。[结论] 以大米蛋白为氮源培养菌株JWG-D15，蛋白酶SoPRO产量最高；蛋白酶SoPRO制得的大米寡肽，其得率是目前行业最高。本研究既丰富了大米寡肽的制备用酶的种类，又为深入大米寡肽产业化提供一定理论基础。

关键词:大米蛋白;寡肽;蛋白酶;沙雷氏菌

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.