Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, Guangxi University, Nanning 530004, Guangxi, China; State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning 530004, Guangxi, China; College of Life Science and Technology, Guangxi University, Nanning 530004, Guangxi, China.
College of Life Science and Technology, Guangxi University, Nanning 530004, Guangxi, China.
Bioresour Technol. 2014 Mar;155:104-10. doi: 10.1016/j.biortech.2013.12.086. Epub 2013 Dec 27.
A thermophilic strain Bacillus subtilis GXA-28 with capability of γ-PGA production was characterized, and its product was identified. The effect of temperatures on cell growth, γ-PGA yield and molecular weight were investigated. Results showed that γ-PGA yield reached 19.92g/L at 45°C with a high productivity of 0.91g/L/h, and the molecular weight reached 3.03×10(6)Da. Then, the flux distribution and the key enzyme activities at 2-oxoglutarate branch under specified temperature were determined to illustrate the possible metabolic mechanism contributing to the improved γ-PGA production. Results indicated that the fluxes from iso-citrate to 2-oxoglutarate and from 2-oxoglutarate to glutamate were increased with high activity of isocitrate dehydrogenase and glutamate dehydrogenase, which led to enhance γ-PGA production. This work firstly employed temperature control strategy to improve γ-PGA production, and provided novel information on the metabolic mechanism of γ-PGA biosynthesis in Bacillus species.
一株具有γ-PGA 生产能力的嗜热菌株枯草芽孢杆菌 GXA-28 被鉴定并对其产物进行了鉴定。考察了温度对细胞生长、γ-PGA 产率和分子量的影响。结果表明，在 45°C 下γ-PGA 的产率达到 19.92g/L，具有 0.91g/L/h 的高生产力，分子量达到 3.03×10(6)Da。然后，在指定温度下确定 2- 酮戊二酸分支处的通量分布和关键酶活性，以阐明可能有助于提高γ-PGA 生产的代谢机制。结果表明，异柠檬酸到 2- 酮戊二酸和 2- 酮戊二酸到谷氨酸的通量增加，异柠檬酸脱氢酶和谷氨酸脱氢酶的活性高，导致γ-PGA 产量增加。本工作首次采用温度控制策略来提高γ-PGA 的产量，并为芽孢杆菌属中γ-PGA 生物合成的代谢机制提供了新的信息。
