产低酰基结冷胶重组菌株的构建及发酵培养基优化

Construction and fermentation medium optimization of recombinant strain producing low-acyl gellan gum

为获得产低酰基结冷胶的少动鞘氨醇单胞菌(Sphingomonas paucimobilis)重组菌株,该研究以少动鞘氨醇单胞菌ATCC31461为出发菌株,采用RedET同源重组技术构建乙酰基转移酶缺失重组菌株,并以产胶率为响应值,采用单因素试验及响应面法对其发酵培养基进行优化。结果表明,成功获得乙酰基转移酶缺失重组菌株LY126,与出发菌株相比,其合成的结冷胶中乙酰基含量(1.66%)降低32.79%,产胶率(1.53%)提高8.65%。重组菌株LY126产低酰基结冷胶的最优培养基组成为葡萄糖50.0 g/L、豆粕8.0 g/L、K2HPO45.0 g/L、KH2PO45.0 g/L、MgSO40.9 g/L,在此条件下,低酰基结冷胶产率可达2.38%,比优化前提高55.40%。

In order to obtain the recombinant strain of Sphingomonas paucimobilis producing low-acyl gellan gum,using S.paucimobilis ATCC31461 as the starting strain,the acetyltransferase-deficient recombinant strain was constructed by RedET homologous recombination technology.Using low-acyl gellan gum yield as response value,and the fermentation medium was optimized by single factor test and response surface method.The results showed that the acetyltransferase-deficient recombinant strain LY126 was successfully obtained,and the acetyl content(1.66%)in the gellan gum synthesized by it was 32.79%lower than that synthesized by starting strain,and the low-acyl gellan gum yield(1.53%)increased 8.65%.The optimum medium composition for the production of low-acyl gellan gum by strain recombinant LY126 was glucose 50.0 g/L,soybean meal 8.0 g/L,K2HPO45.0 g/L,KH2PO45.0 g/L and MgSO40.9 g/L.Under these conditions,the yield of low-acyl gellan gum was 2.38%,which was 55.40%higher than before optimization.