Screening and acid resistance acclimatization of protease-producing Bacillus and enzymatic characteristics analysis
A high protease-producing strain was screened from high-temperature Daqu by transparent circle method and protease activity determina-tion,and identified by morphological observation and molecular biological technique.The acid tolerance of the screened strain was further acclimated,the tolerance was analyzed,and theenzymatic characteristics of protease produced by the screened strain were studied.The results showed that thes-train Cy3 with high protease activity was isolated and screened,and identified as Bacillus cereus,and the protease activity was 505.0 U/ml under the optimal growth condition of pH 6.The strain Cy3-acclimation was obtained after acid tolerance acclimatization for strain Cy3,and its growth pH was successfully acclimated to 5,and the OD600nm value increased by 2.54 times after culture for 15 h.The optimum reaction temperature of protease pro-duced by strain Cy-3-acclimation was promoted from 60 ℃ to 70 ℃,and the optimum reaction pH was 6.However,the protease activity and stability were slightly decreased.The strain Cy3-acclimation had high tolerance to NaCl and glucose,with the maximum tolerance mass fraction of 15％and 60％,respectively,and could still grow when the volume fraction of ethanol and lactic acid was 8％and 3％,respectively.
proteaseBacillusisolation and identificationacid tolerance acclimationenzymatic characteristics
NETL
NSTL
万方数据
维普
