利用重组枯草芽孢杆菌产Bacillus pumilus来源的γ-谷氨酰转肽酶及其在L-茶氨酸合成中的应用

Efficient Production ofBacillus pumilusγ-Glutamyl Transferase in B. subtilis and Its Application of Biosynthesis of L-Theanine

DOI：10.3969/j.issn.1673-1689.2019.10.010

中文关键词: γ-谷氨酰转肽酶 L-茶氨酸 枯草芽孢杆菌

英文关键词: γ-glutamyl transferase,L-theanine,Bacillus subtilis

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中文摘要:

L-茶氨酸作为一种非天然氨基酸对人体健康具有多方面的功效，其作为食品饮品添加剂和制药原料的需求量日益增加。本文以安全菌株Bacillus subtilis168作为宿主菌，表达生产B. pumilus来源的γ-谷氨酰转肽酶（GGT）。结果显示，该来源GGT成功在B. subtilis168中实现了胞外分泌表达。最后，通过关键转化条件优化，并结合批次流加策略，该重组GGT能够在16 h催化合成50.8 g/L的L-茶氨酸，该结果可以和已报道的以大肠杆菌作为宿主菌表达GGT并催化合成L-茶氨酸的产量相媲美。

英文摘要:

L-theanine，is a nonproteic amino acid which recently has an increasing demand as it is applied in food and pharmaceutical industries. In this study，a GRAS（Generally Recognized As Safe） strainBacillus subtilis168 was used as the host to produce a novel γ-glutamyl transferase（GGT） fromB. pumilusML413. The enzyme produced was applied to L-theanine synthesis. Subsequently，glutamine conversion efficiency with the GGT was optimized. Finally，for the improved L-theanine production，a fed-batch strategy was introduced and the maximum titer of L-theanine reached 50.8 g/L at 16 h. This titer could be comparable to the efficient but toxic GGT producer recombinant E.coli.

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