渔源解淀粉芽孢杆菌CQN-2菌株培养基及发酵条件优化

Optimization of culture medium and fermentation conditions of Bacillus amyloliquefaciens CQN-2 isolated from aquatic animal

CQN-2是一株具有抗病、促生长等多种功能的肠道内源性解淀粉芽孢杆菌。为研究其最佳培养条件,从而为规模化生产发酵提供依据,本文以菌体生物量为指标,采用单因素试验和正交试验对CQN-2菌株的最适培养基及发酵条件进行优化。结果表明,CQN-2菌株的最适碳源为可溶性淀粉,最适氮源为细菌学蛋白胨,经优化后的最佳培养基配方为可溶性淀粉20 g/L、细菌学蛋白胨30 g/L、糖蜜50 g/L、KH 2 PO 40.5 g/L、MgSO 40.5 g/L、NaCl 0.3 g/L、Mn^2+5 mmol/L、Al 3+1 mmol/L;最佳发酵培养条件为初始pH值7.0,接种量为3%、装液接种量25 mL/250 mL;使用优化后的培养基将CQN-2接种于5 L发酵罐进行高密度发酵培养36 h后的活菌数为3.03×10^12 CFU/mL。

Bacillus amyloliquefaciens CQN-2 was an endogenous bacteria isolated from the intestinal tract of Apostichopus japonicus,which showed many biological activities such as disease resistance and growth promotion.To investigate the optimal culture medium components and fermentation conditions,the bacterial biomass was used as indicator to determine the optimal conditions of CQN-2 strain growth by single factor test and orthogonal experiment design.The optimal nutritional conditions and optimal fermentation conditions were screened.The results showed that the optimum carbon source of CQN-2 strain was soluble starch,and the optimum nitrogen source was bacteriological peptone.The optimal medium composition was as followed:soluble starch 20 g/L,bacteriological peptone 30 g/L,molasses 50 g/L,KH 2 PO 40.5 g/L,MgSO 40.5 g/L,NaCl 0.3 g/L,Mn^2+5 mmol/L and Al 3+1 mmol/L.The optimum fermentation conditions were initial pH 7.0,inoculation rate was 3%,and medium capacities was 25 mL/250 mL.Then the strain CQN-2 was prepared with high density fermentation in 5 L fermentation tank under optimized conditions for 36 h,while the viable cell count of strain CQN-2 was 3.03×10^12 cfu/mL.