Panahi R, Vasheghani-Farahani E, Shojaosadati S A, Bambai B
Mol Biol (Mosk). 2014 Nov-Dec;48(6):970-6. doi: 10.7868/s0026898414060135.
The reliable production of heterologous proteins is important in the field of industrial biotechnology. This can be achieved by applying auto-inducible gene expression systems. The development of a Bacillus subtilis expression plasmid harboring SigB-dependent ohrB promoter was reported. The expression system was subjected to high cell density cultivation to produce xylanase as a stable model protein. The recombinant strain was cultured in a synthetic medium containing glucose as the carbon source. The exponential fed-batch feeding strategy was applied to prevent substrate inhibition. A sharp increase of xylanase activity (about 6-fold) at the end of the fermentation was observed as a result of sigma factor B (SigB) protein activation, supporting auto-inducibility of the expression system. For the control strain a specific induction of the xylanase activity was not observed. The recombinant strain was capable to offer a 5-fold increase in xylanase activity in comparison with the control strain. In addition, the constructed system displayed catabolite repression resistance ability. This SigB-dependent expression system can be considered as a biotechnology tool and an alternative to eliminate the cost of conventional inducers, e.g. isopropyl-β-galactopyranoside.
在工业生物技术领域，可靠地生产异源蛋白非常重要。这可以通过应用自诱导基因表达系统来实现。有报道称开发了一种携带依赖SigB的ohrB启动子的枯草芽孢杆菌表达质粒。该表达系统进行了高密度培养，以生产木聚糖酶作为一种稳定的模型蛋白。重组菌株在以葡萄糖为碳源的合成培养基中培养。采用指数补料分批补料策略以防止底物抑制。由于sigma因子B（SigB）蛋白的激活，在发酵结束时观察到木聚糖酶活性急剧增加（约6倍），这支持了该表达系统的自诱导性。对于对照菌株，未观察到木聚糖酶活性的特异性诱导。与对照菌株相比，重组菌株的木聚糖酶活性提高了5倍。此外，构建的系统显示出抗分解代谢物阻遏能力。这种依赖SigB的表达系统可被视为一种生物技术工具，并且是消除常规诱导剂（如异丙基-β-吡喃半乳糖苷）成本的一种替代方法。
