pgi基因敲除对大肠杆菌利用混合碳源的影响

Effects of pgi Knockout on Mixed Carbon Source Utilization of Escherichia Coli

木质纤维素是地球上最丰富的碳源,可广泛应用于生物燃料和生物化工。但是由于分解代谢阻遏,不能完全利用木质纤维素降解产物中获得的多种糖类,严重制约了木质纤维素的商业应用。研究主要构建了一株可以同时消耗葡萄糖、果糖、木糖的菌株E.coli BW25113△pgi,并探讨了其分别在好氧和厌氧条件下以葡萄糖、果糖、木糖为混合碳源时的碳源利用情况。敲除pgi后,葡萄糖、果糖、木糖三种糖被同时消耗。研究通过发酵数据、基因转录水平数据和代谢流分析数据阐述了敲除pgi解除分解代谢阻遏的机理。pgi基因的敲除导致pts G转录水平下降,增加了c AMP-Crp的含量,从而解除分解代谢阻遏,实现了混合碳源的共利用,为木质纤维素的开发利用提供了新的思路。

Lignocellulosic biomass is an attractive carbon source for bio-based fuel and chemical production. However, carbon catabolite repression and inability to use multiple sugars derived from lignocellulosic biomass hinder its commercial usage. This research constructed an Escherichia coli △pgi strain, which can simultaneously consume glucose, fructose and xylose. The effects of modulating pgi(△pgi) gene on the consumption of multiple carbon sources were investigated under both aerobic and anaerobic conditions. The results show that three carbon sources are consumed simultaneously with pgi knockout. The overall regulation mechanisms are clarified based on fermentation data, gene transcript analysis and flux analysis. The knockout of pgi gene leads to the degradation of pts G transcription, increase of c AMP-Crp and relaxation of catabolite repression, which may affect co-consumption of multiple carbon sources.