一株嗜热纤维素酶生产菌的分离、鉴定及酶学研究

目的]对一株嗜热纤维素酶生产菌进行分离、鉴定及酶学研究。方法]从草堆下土壤中分离筛选得到一株纤维素酶生产菌,根据形态观察和16S rRNA序列分析对其进行鉴定,并对该菌的产酶条件和酶的稳定性进行研究。结果]将分离得到的菌株命名为BSC6-1,并确定该菌可能属于芽孢杆菌(Bacillus sp.)的一个新亚种。该菌的最佳发酵培养基为1%CMC-Na,0.2%K2HPO4,0.05%MgSO4·7H2O,1%蛋白胨,0.002%CaCl2,0.000 4%FeSO4,pH 7.0。在接种量为7%的条件下,55℃培养5 d后,该菌产酶量达最高,羧甲基纤维素酶活(CMCA)与滤纸酶活(FPA)分别达10.25和8.90 U/ml。该纤维素酶的最佳酶促反应条件为55℃、pH 7.0。在温度低于70℃的条件下,该酶的相对酶活力保持在73%以上,证明该酶具有热稳定性;在pH 6.5~8.0范围内,该酶的相对酶活力保持在90%以上。结论]该研究为BSC6-1菌株在纤维素资源方面的开发和利用提供了理论和技术基础。

Study on Isolation,Identification and Characterization of A Thermophilic Cellulase-producing Strain

Abstract Objective ] The aim was to isolate and identify a thermophilic cellulose-producing strain, and study the characterization of the en- zyme. Method] A cellulose-producing strain was isolated from the soil under the haystack,and was identified according to the observation of its morphology and 16S rRNA sequence analysis. Then the condition of enzyme production and stability of the enzyme were studied. Result] The iso- lated strain was named BSC6-1 ,and was identified belong to a new subspecies of Bacillus sp.. The best fermentation medium of the strain was 1% CMC-Na,O. 2% K2 HPO4 ,0.05 MgSO4 ~ 7H2 O, 1% peptone,0.002% CaC12 ,0.000 4% FeSO4, pH 7.0. In the condition of 7% inoculation, the amount of enzyme was the highest after culture under 55℃ for 5 days, and the carboxymethyl cellulase （CMCA） and filter paper activity （FPA） was 10.25 and 8.90 U/ml respectively. The best promoting reaction conditions of the cellulase enzyme was 55 ℃ and pH 7.0. The rela- tive enzyme activity of the enzyme remained at more than 73 % at temperatures below 70 ℃, showed the enzyme has thermal stability;the relative enzyme activity of the enzyme remained at more than 90% in the pH 6.5 - 8.0 range. Conclusion] The study provided a theoretical and techni- cal basis for the develonment and utilization of BSC6-1 strain in cellulose resources.