为获得含猪脂联素球状结构域gAd基因的重组乳酸乳球菌的高效表达,对其表达条件和培养基配方进行了优化。首先采用单因素分析法确定重组乳球菌最佳诱导剂浓度、诱导时间点(OD600)和诱导后培养温度,以及培养基中的乳糖浓度、氮源浓度、Na2HPO4浓度和MgSO4浓度对表达量的影响;之后通过正交试验,确定重组乳酸乳球菌的最佳表达条件。结果显示,其最佳诱导剂nisin浓度为30ng/mL、诱导的时间点是OD600≈0.4、诱导后培养温度为25℃;最佳培养基配方是:乳糖添加量为7%、大豆蛋白胨为2.7%、酵母膏为1.3%、Na2HPO4浓度为0.25%、MgSO4浓度为0.02%。优化后,脂联素的表达量为29.4%的总蛋白含量。

In this paper we studied the induction conditions and cultural media of recombinant Lactococcus lactis NZ9000-gAd for expression of porcine adiponectin protein.The aim of this study was to obtain maximum yield of protein gAd.Firstly,the amount of nisin added for induction,the time point of induction(cell density of the culture),and the temperature for induction in improved M17G culture medium were optimized through single factor experiments.Then the concentrations of lactose,nitrogen source,Na2HPO4 and MgSO4 in basic medium were also determined through single factor experiments.Finally,the optimal induction and cultural media were determined though orthogonal experiment.The optimized conditions of induced expression were obtained.The amount of nisin was 30ng/mL,the time point of induction was OD600≈0.4,and the culture temperature after induction was 25℃.The optimal cultural medium contained 7% lactose,2.7% peptone,1.3% yeast extract,0.25% Na2HPO4,and 0.02% MgSO4.In optimization conditions the amount of expressed protein-gAd could account for 29.4% of total protein.