Abstract

Poly-γ-glutamate (γ-PGA) is a natural macromolecule peptide, and is widely used in the food, medicine, and pharmaceutical industries. In this study, heat- and osmotic shock were used to improve the production of γ-PGA in Bacillus subtilis ZJS18, and its molecular mechanism was explored. The results indicated that the heat- and osmotic shock significantly promoted the production of γ-PGA owing to the stress response of B. subtilis cells to adverse environment. The highest concentrations of γ-PGA reached 14.53 and 15.98 g/l under heat- and osmotic shock, respectively. The activities of five enzymes related to the metabolism of the endogenous glutamate were determined and analyzed. It was found that the activities of glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase, glutamate dehydrogenase and glutamate synthase were significantly altered during heat- and osmotic shock, while the activity of α-ketoglutarate dehydrogenase only showed a little alteration. This study provides a basis for the industrial production and use of γ-PGA, and for understanding its biosynthetic mechanism in B. subtilis ZJS18.

摘要

聚-γ-谷氨酸（γ-PGA）是一种天然的大分子肽，广泛用于食品，医药和制药行业。本研究利用热和渗透休克提高枯草芽孢杆菌ZJS18中γ-PGA的产生，并探讨了其分子机制。结果表明，由于枯草芽孢杆菌的应激反应，热和渗透休克显着促进了γ-PGA的产生。细胞对不利的环境。在热和渗透性休克下，γ-PGA的最高浓度分别达到14.53和15.98 g / l。测定和分析了与内源性谷氨酸代谢相关的五种酶的活性。发现在热和渗透性休克期间，葡萄糖6-磷酸脱氢酶，异柠檬酸脱氢酶，谷氨酸脱氢酶和谷氨酸合酶的活性发生了显着变化，而α-酮戊二酸脱氢酶的活性仅表现出很小的变化。该研究为γ-PGA的工业化生产和应用以及了解其在枯草芽孢杆菌ZJS18中的生物合成机理提供了基础。