产冷活性β-半乳糖苷酶的菌株的筛选、鉴定及酶特性研究

Isolation,identification and enzyme-characteristics of a strain producing cold-active β-galactosidase

目的筛选新的产冷活性β-半乳糖苷酶的菌株,为解决目前工业用β-半乳糖苷酶耗能大、pH要求高的难题创造条件。方法通过含X-gal(5-溴-4-氯-3-吲哚-β-D-半乳糖苷)的筛选培养基在油田附近土壤中分离纯化菌株并进行鉴定,以邻硝基苯β-D-半乳吡喃糖苷(ONPG)为底物测定酶特性。结果获得了一株新的产冷活性β-半乳糖苷酶的菌种,经形态学和16 s rDNA比对,初步鉴定为变形斑沙雷菌属,命名为Serratia proteamaculanssp.L3。该菌株所产β-半乳糖苷酶为胞外酶,粗酶液的最适温度为25℃,最适pH为7.0。结论产冷活性β-半乳糖苷酶的菌株的发现及酶特性的研究为进一步分子生物学机制的研究奠定了基础。

Objective To obtain a psychrotrophic bacterial strain capable of producing cold-active β- galactosidase. Methods The bacterial strain was isolated from soils near oil field using X-gal （ 5-bromo-4- chloro-3-indolyl-β-D-galaetopyranoside ） as an indicator, and the characteristics of the enzyme was determined with ONPG （O-Nitrophenyl-β-D-Galactopyranoside）. Results A strain L3 identified as Serratia proteamaculans according to the morphological and the molecular characterization is found. Researches on the activity of the β-galactosidase from L3 show that the optimal temperature and pH for the activity of crude enzyme is 25 ℃ and 7. 0 respectively. Conclusion The obtain!ng of the strain and the study the characteristics of the enzyme provide a good foundation for further research on the molecular mechanisms.