Enhanced production of poly-gamma-glutamic acid via optimizing the expression cassette of Vitreoscilla hemoglobin in Bacillus licheniformis

文献类型： 外文期刊

第一作者： Zhang, Qing

作者： Zhang, Qing;Chen, Yaozhong;Gao, Lin;Chen, Jian'gang;Ma, Xin;Cai, Dongbo;Wang, Dong;Chen, Shouwen;Chen, Jian'gang;Gao, Lin

作者机构：

关键词： Vitreoscilla hemoglobin; Expression element; Twin-arginine translocation; Poly-gamma-glutamic acid; Bacillus licheniformis

期刊名称：SYNTHETIC AND SYSTEMS BIOTECHNOLOGY （ 影响因子：4.692； 五年影响因子：5.23 ）

ISSN： 2405-805X

年卷期： 2022 年 7 卷 1 期

页码：

收录情况： SCI

摘要： Poly-gamma-glutamic acid (gamma-PGA) is a natural polymer with various applications, and its high-viscosity hinders oxygen transmission and improvement of synthesis level. Vitreoscilla hemoglobin (VHB) has been introduced into various hosts as oxygen carrier, however, its expression strength and contact efficiency with oxygen hindered efficient oxygen transfer and metabolite synthesis. Here, we want to optimize the expression cassette of VHB for gamma-PGA production. Firstly, our results implied that gamma-PGA yields were enhanced when introducing twin-arginine translocation (Tat) signal peptides (SPYwbN, SPPhoD and SPTorA) into VHB expression cassette, and the best performance was attained by SPYwbN from Bacillus subtilis, the gamma-PGA yield of which was 18.53% higher than that of control strain, and intracellular ATP content and oxygen transfer coefficient (K(L)a) were increased by 29.71% and 73.12%, respectively, indicating that VHB mediated by SPYwbN benefited oxygen transfer and ATP generation for gamma-PGA synthesis. Furthermore, four promoters were screened, and (P)Pvgb was proven as the more suitable promoter for VHB expression and gamma-PGA synthesis, and gamma-PGA yield of attaining strain WX/pPvgb-YwbN-Vgb was further increased to 40.59 g/L by 10.18%. Finally, WX/pPvgb-YwbN-Vgb was cultivated in 3 L fermentor for fed-batch fermentation, and 46.39 g/L gamma-PGA was attained by glucose feeding, increased by 49.26% compared with the initial yield (31.01 g/L). Taken together, this study has attained an efficient VHB expression cassette for oxygen transfer and gamma-PGA synthesis, which could also be applied in the production of other metabolites.

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