耐低温兼性厌氧蛋白酶产生菌192的筛选、鉴定及酶学性质

Screening and Identification of Psychrotolerant and Anaerobic Protease-Producing Strain and Characterization of Protease

为了提高厌氧水解效率,采用双层平板法筛选出一株耐低温兼性厌氧蛋白酶产生菌192。经形态、生理生化和16S rDNA序列分析鉴定为蜡状芽孢杆菌(Bacillus cereus),对其产酶条件进行了初步研究。结果表明,该菌的最适生长温度为30℃,生长8～12 h达对数期,初始pH 7.5时酶活力最高。蛋白酶最适反应温度为45℃、pH 7.0,酶活力最高达39.3 U/mL。该酶在50℃以下,pH 6.0～9.0性能稳定。在60℃以上热稳定性很差,70℃保存1 h酶活力全部丧失。

In order to improve the efficiency of the anaerobic hydrolysis,the psychrotolerant and anaerobic protease-producing strain 192,was screened using double-plate method.The strain was identified as Bacillus cereus based on the results of morphological,physiological,biochemical and 16S rDNA analysis.Then its optimal protease-producing conditions were studied.The results showed that the optimum growth temperature of this strain was 30 ℃ and its enzyme activity was highest when the initial pH 7.5,after 8～12 h of growth.The optimal reaction condition of this protease was 45 ℃ and pH 7.0,its enzyme activity could be up to 39.3 U/mL.At the conditions of pH 6.0～9.0 and lower than 50 ℃,the protease was stable.The protease was unstable at the temperature higher than 60 ℃,it would completely lose activiy when storing at 70 ℃ for 1 h.