摘要
Abstract
The present study was designed to identify the cutin degrading strain X8P, their fermentation condi⁃tions and enzymatic properties were also explored, to investigate the degradation of plant cuticular surface, and to improve the possible new schemes for the utilization of plant fiber. The strain X8P was identified by mor⁃phology observation and 16S rDNA sequencing, and the optimal fermentation conditions of carbon source, ni⁃trogen source, fermentation temperature and fermentation time for enzyme production were investigated. After precipitating crude extracellular enzyme protein by ammonium sulfate, we studied the optimum pH and pH sta⁃bility and temperature and temperature stability of crude extracellular enzyme, and the effect of organic sol⁃vents, surfactants and metal ions on crude enzyme. The results showed as follows:1) the strain X8P was suc⁃cessfully identified as Acetobacter orientalis by colony morphological characteristic observing and 16S rDNA sequencing. 2) The optimal fermentation conditions of the strain X8P were temperature 37 ℃ and fermentation time for 4 days in the lysogeny broth ( LB) medium. The LB medium supplemented with 1% olive oil and glu⁃cose was significantly promoted enzyme production, and supplemented with 1% soluble starch inhibited the en⁃zyme production. 3) The optimum temperature and pH of the strain X8P’ s extracellular esterase with good pH stability were 45℃ and pH 6.5. In tested organic solvents, the enzyme exhibited part of cutinolytic esterase ac⁃tivity only in dimethyl sulfoxide ( DMSO ) ( 50%) . Tween⁃20 ( 1 mmol/L ) , Tween⁃80 ( 1 mmol/L ) and Triton⁃100 ( 1 and 10 mmol/L ) could improve the extracellular enzyme activity as 3% to 35%. Metal ions such as K+, Mn2+( 1 and 10 mmol/L) could improve extracellular enzyme activity as 2% to 20%. Therefore, the strain X8P has certain enzyme potential and application prospects, worthy of further study.关键词
角质/角质酶/角质降解菌/发酵条件优化/酶学性质Key words
cutin/cutinase/cutin degrading bacteria/fermentation conditions optimization/enzymatic proper-ties分类
农业科技
