摘要
对一株产γ-聚谷氨酸的地衣芽孢杆菌(Bacillus licheniformis CICC10099)进行了诱变筛选及摇瓶发酵条件的初步优化,以期得到γ-聚谷氨酸高产菌株并进一步提高其产能。实验考察了不同诱变剂量下的菌体的致死率和正突变率,以确定最佳诱变条件。结果表明:60Coγ射线最佳的诱变剂量为200Gy时,致死率大于90%,正突变率高达13.3%。在上述剂量下,经60Coγ射线诱变后分离筛选得到一株高产突变株Bacillus licheniformis S16,摇瓶实验表明γ-聚谷氨酸的含量达到16.9g·L-1,较出发菌株CICC10099提高72.4%。并且采用单因素法初步优化了摇瓶发酵培养基,优化后的培养基组成为:柠檬酸12g·L-1,甘油80g·L-1,氯化铵6g·L-1,L-谷氨酸15g·L-1,K2HPO41g·L-1,CaCl2.2H2O0.1g·L-1,FeCl3.6H2O0.05g·L-1,MgSO4.7H2O0.75g·L-1,MnSO.H2O0.1g·L-1,pH7.5;利用优化的培养基在250mL三角烧瓶装液量50mL,37℃,180r·min-1的条件下培养80h,发酵液中的γ-PGA含量最高,可达到18.9g·L-1。
Bacillus licheniformis is an important strain for γ-poly glutamic acid （γ-PGA） production. The screening of high γ-PGA producing mutant and its culture conditions were investigated. Bacillus licheniformis CICC10099 was mutagenized by 60↑Co γ-irradiation and the results show that 200 Gy is the optimum irradiation dosages with high positive mutation rate of 13% and death rate of above 90%. A new mutant Bacillus licheniformis S16 was isolated after 60↑Co γ-irradiation and it has genetic stability of high γ-PGA producing ability even after several generation cultures. Compared with the yield of the original strain CICC10099, the γ-PGA yield of mutant S16 increases from 9.8 g.L^-1 to 16.9 g.L^-1, and the increase rate reaches 72.4%. The optimal culture medium for S16 was obtained and it contains as follows： citric acid 12 g.L^-1, glycerol 80 g.L6-1, ammonium chlorine 6 g.L^-1, L-glutamate 15 g.L^-1, K2HPO4 1 g.L6-1, CaCl2.2H2O 0.1 g.L^-1, FeCl3.6H2O 0.05 g.L^-1, MgSO4.7H2O 0.75 g.L^-1 and MnSO4.H2O 0.1 g.L^-1. Using the above optimized culture medium and after culture time of 80 h, tile γ-PGA yield of S16 can reach 18.9 g.L^-1 under the culture conditions of 37℃, pH 7.5 and 180 r.min^-1.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2007年第5期820-825,共6页
Journal of Chemical Engineering of Chinese Universities
基金
国家自然科学基金(30570411)
国家'973'计划资助项目(2007CB714305)
浙江省重点科技项目
教育部留学人员基金项目
