本研究主要目的探究传统老面中戊糖片球菌的分子特性。8株戊糖片球菌分离自中国中北部不同老面，比较它们发酵葡萄糖产酸的能力，利用脱脂乳分离培养基探究戊糖片球菌产蛋白酶的能力，使用沉淀蛋白法提取胞外分泌蛋白并进行蛋白凝胶电泳分析胞外分泌蛋白，使用Folin-酚法比较不同戊糖片球菌蛋白酶活力。结果表明8株戊糖片球菌均有代谢葡萄糖产酸的能力，其中P.P005能力最佳，经过发酵pH值降低0.41；8株戊糖片球菌均可产生明显水解圈，均具有产蛋白酶的能力；胞外蛋白结果显示P.P002菌株和P.P008菌株分泌蛋白浓度最大，最高酶活力在1057.27~1242.56 U/mL之间，在各自最适条件下，产蛋白酶活力从大到小依次是P.P002、P.P001、P.P005、P.P006 、P.P003、P.P008、P.P007、P.P004；ERIC-PCR分析亲缘关系分析显示所有的菌株的相似度都在86%以上。本研究为探究传统老面中戊糖片球菌发挥的作用奠定了分子研究的基础。

The molecular properties of P. pentosaceus separated from traditional sourdoughs were investigated in this work. The 8 strains of P. pentosaceus were isolated from different Laomians in central and northern China. Acid producing abilities generated by fermenting glucose were compared. The skimmed milk separation medium was used to investigate the ability of protease production of P. pentosaceus. Extracellular proteins were extracted by precipitation protein method and protein gel electrophoresis was used to analyze extracellular proteins. Furthermore, the Folin-phenol method was used to compare the protease activity produced by different P. pentosaceus. The results showed that these P. pentosaceus had the ability to metabolize glucose and acid production, of which P.P005 had the best ability, and the pH value was reduced by 0.41 at the end of fermentation. All P. pentosaceus can produce obvious hydrolytic circles when cultured on skim milk plates, therefore they had the ability to produce protease. The strain P.P002 and strain P.P008 had the highest concentration of secreted protein, and the highest enzyme activity was between 1057.27 to 1242.56 U/mL by exploring the protease activity of different strains. Under their optimal conditions, the protease production activity were followed by P.P002, P.P001, P.P005, P.P006, P.P003, P.P008, P.P007, and P.P004. Finally, their relationship was analyzed by ERIC-PCR, and the results showed that the similarity of all strains was within 86%. This study provides the foundation for molecular research to explore the role played by P. pentosaceus in traditional Laomian.

中央高校基本科研业务费基金资助（2662016PY102）