热稳定碱性脂肪酶产生菌的筛选及发酵条件的优化

Screening of thermostable alkaline lipase producing strain and its optimal fermentation condition

从渤海湾盐碱地被油污染的土样中分离筛选出6株产热稳定碱性脂肪酶菌株。其中菌株1-7产脂肪酶能力较强,其最高酶活为8.67U/mL。根据其16S rDNA序列分析和Biolog生理生化分析,初步鉴定为醋酸钙不动杆菌(Acinetobacter calcoaceticus)。初步酶学性质研究表明该菌所产脂肪酶具有较好的热稳定性,最适作用pH为9.0。摇瓶实验表明,该菌株最适产酶培养基为(g/L):玉米粉10,黄豆饼粉20,K_2HPO_4 1,NaNO_3 5,橄榄油10。最适产酶条件为:初始pH 8.0,培养温度37℃,培养时间29 h。接种量为2%,250 mL摇瓶装液量为30 mL。

Six stains of bacterium producing thermostable alkaline lipase were isolated from the soil collected from bay of Bohai. The stain 1-7 showed high ability of producing lipase with the maximal level of 8.67 U/mL, which was identified as Acinetobacter calcoaceticus on the basis of the sequence of 16S rRNA and Biolog. The lipase showed good thermosta- bility. The optimal pH of the lipase was 9.0. The optimal medium for lipase production was obtained with the composition of （g/L） ： corn flour 10, bean flour 20, K2HPO4 1, NaNO3 5 and olive oil 20. The optimal conditions for fermentation were as follows： initial pH 8.0, the temperature 37℃, fermentation period 29 h and the shake flask capaeity of 30mL/250 mL with the germ concentration of 2 %.