Sakurai Tetsuo, Mizuno Shoji, Miyahara Yuki, Hiroe Ayaka, Taguchi Seiichi, Tsuge Takeharu
Department of Materials Science and Engineering, Tokyo Institute of Technology, Yokohama, Japan.
MIRAI, Japan Science and Technology Agency (JST), Saitama, Japan.
Front Bioeng Biotechnol. 2022 Feb 25;10:829134. doi: 10.3389/fbioe.2022.829134. eCollection 2022.
Poly(3-hydroxybutyrate) [P(3HB)] is the most representative polyhydroxyalkanoate (PHA), which is a storage polyester for prokaryotic cells. P(3HB)-producing recombinant secretes diethylene glycol (DEG)-terminated 3HB oligomers (3HBO-DEG) through a PHA synthase-mediated chain transfer and alcoholysis reactions with externally added DEG. The purpose of this study was to optimize the culture conditions for the secretory production of 3HBO-DEG with jar fermenters. First, the effects of culture conditions, such as agitation speed, culture temperature, culture pH, and medium composition on 3HBO-DEG production, were investigated in a batch culture using 250-ml mini jar fermenters. Based on the best culture conditions, a fed-batch culture was conducted by feeding glucose to further increase the 3HBO-DEG titer. Consequently, the optimized culture conditions were reproduced using a 2-L jar fermenter. This study successfully demonstrates a high titer of 3HBO-DEG, up to 34.8 g/L, by optimizing the culture conditions, showing the feasibility of a new synthetic strategy for PHA-based materials by combining secretory oligomer production and subsequent chemical reaction.
聚（3-羟基丁酸酯）[P(3HB)]是最具代表性的聚羟基脂肪酸酯（PHA），它是原核细胞的一种储存聚酯。产生P(3HB)的重组体通过PHA合酶介导的链转移以及与外部添加的二甘醇（DEG）的醇解反应分泌二甘醇封端的3HB低聚物（3HBO-DEG）。本研究的目的是利用罐式发酵罐优化分泌生产3HBO-DEG的培养条件。首先，在使用250毫升小型罐式发酵罐的分批培养中，研究了培养条件，如搅拌速度、培养温度、培养pH值和培养基组成对3HBO-DEG产量的影响。基于最佳培养条件，通过补料分批培养补加葡萄糖以进一步提高3HBO-DEG的滴度。因此，使用2升罐式发酵罐重现了优化的培养条件。本研究通过优化培养条件成功证明了高达34.8克/升的3HBO-DEG高滴度，显示了通过结合分泌低聚物生产和后续化学反应来合成基于PHA的材料的新策略的可行性。
