Screening and optimization of fermentation conditions of Bacillus aryabhattai derived from Monopterus albus
In order to solve the problems of the low feeding rate,incomplete digestion of Monopterus albus,and nitrogen pollution of water,the study aimed to isolate high-yield protease producing strains from artificially cultivated Monopterus albus,which will provide strain resources for the production of microbial proteases and the development of probiotics in the future.High-yield protease producing strains were preliminarily isolated from the artificially cultivated Monopterus albus by the combination of the transparent circle method of skimmed milk powder culture medium for primary screening and the Folin-phenol method for secondary screening to measure protease activity.The safety of the strains was tested through a hemolysis test and a drug sensitivity test,and the strains were identified by adopting a combination method of the physiological and biochemical characteristics of the strain.The fermentation conditions for protease production were optimized through single factor and orthogonal experiments.A high-yield protease producing strain named Ma-4 was screened,and it was identified as Bacillus aryabhattai,which can also produce the hydrogen peroxide enzyme.Its optimal enzyme production conditions were the fermentation time of 48 h,the fermentation temperature of 36 ℃,the optimal amount of soluble starch of 15 g/L,the optimal amount of beef powder of 15 g/L,and the pH value of 6.0.After optimization,the enzyme activity increased to 288.14 U/mL,representing a 3.34-fold improvement.The study indicates that the strain Ma-4 is a high protease-producing,catalase-producing,non-hemolytic and drug-resistant Bacillus aryabhattai,which can provide strain resources for the development of micro-ecological preparations of Monopterus albus.
Monopterus albusBacillus aryabhattaiscreening and identificationsafety evaluationoptimization of fermentation conditions
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