BACKGROUND Poly-γ-glutamic acid (γ-PGA) is a promising biopolymer and has been applied in many fields. Bacillus siamensis SB1001 was a newly isolated poly-γ-glutamic acid producer with sucrose as its optimal carbon source. To improve the utilization of carbon source, and then molasses can be effectively used for γ-PGA production, 60cobalt gamma rays was used to mutate the genes of B. siamensis SB1001. RESULTS Bacillus siamensis IR10 was screened for the production of γ-PGA from untreated molasses. In batch fermentation, 17.86 ± 0.97 g/L γ-PGA was obtained after 15 h, which is 52.51% higher than that of its parent strain. Fed-batch fermentation was performed to further improve the yield of γ-PGA with untreated molasses, yielding 41.40 ± 2.01 g/L of γ-PGA with a productivity of 1.73 ± 0.08 g/L/h. An average γ-PGA productivity of 1.85 g/L/h was achieved in the repeated fed-batch fermentation. This is the first report of such a high γ-PGA productivity. The analysis of the enzyme activities showed that they were affected by the carbon sources, enhanced ICDH and GDH, and decreased ODHC, which are important for γ-PGA production. CONCLUSION These results suggest that untreated molasses can be used for economical and industrial-scale production of γ-PGA by B. siamensis IR10.

中文翻译：

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唾液芽孢杆菌IR10从未经处理的糖蜜大量生产聚-γ-谷氨酸。

背景技术聚-γ-谷氨酸（γ-PGA）是一种有前途的生物聚合物，已被应用于许多领域。暹罗芽孢杆菌SB1001是一种新分离的聚-γ-谷氨酸生产者，蔗糖为最佳碳源。为了提高碳源的利用率，然后可以将糖蜜有效地用于γ-PGA的生产，使用60钴γ射线诱变了B. siamensis SB1001的基因。结果筛选了未经处理的糖蜜产生的γ-PGA的芽孢杆菌IR10。分批发酵15h后获得了17.86±0.97g / L的γ-PGA，比其亲本菌株高52.51％。进行分批补料发酵以进一步提高未处理糖蜜的γ-PGA产量，得到41.40±2.01 g / L的γ-PGA，生产率为1.73±0.08 g / L / h。γ-PGA的平均生产率为1。在重复的分批补料发酵中达到了85 g / L / h。这是γ-PGA生产率如此高的首次报道。对酶活性的分析表明，它们受碳源，ICDH和GDH增强以及ODHC降低的影响，这对γ-PGA的生产很重要。结论这些结果表明，未经处理的糖蜜可用于由B. siamensis IR10进行经济和工业规模的γ-PGA生产。