| Beneficial bacterium Bacillus subtilis B908, which has distinct control effect for eye-spot disease caused by Rhizoctonia sp., is isolated from rhizosphere of rice. Bacillus subtilis can form endospore which can be made into preparative. In this study, optimizing the fermentation technology, including fermentation culture media and fermentation condition, was proceeded to enhance the fermentation yield and decrease the cost.About sixteen fermentation culture media, which are suitable for Bacillus sp., were compared on the basis of endospore yield. The medium, which brings the highest yield, was chose as the basic medium for fermentation of Bacillus subtilis B908.Placket-Burman design (PB) and Response Surface Analysis (RSA) were used to find the main factors influence the strain's fermentation among the components of basic medium, and confirm these factors'optimal proportion, respectively.Fermentation medium for the strain Bacillus subtilis B908 were selected by Placket-Burman design and Response Surface Analysis in shake-flask. Results showed that optimum fermentation medium component for strain Bacillus subtilis B908 was corn flour 13.0g,bean flour 20.5g,CaCO3 7.0g,glucose5.0g,fishmeal 5.0g,(NH4)2 SO4 1g,K2HPO-4 0.3g,MgSO4·7H2O 0.2g,MnSO4·H2O 0.2g,water 1000ml. Other fermentation parameters for strain Bacillus subtilis B908 were optimized on the base of the resulting fermentation medium in the shake-flask, they included: temperature, original pH-value, rotation speed, amount of inoculation etc. The obtained best fermentation condition was described as: rotation speed 200 rpm, original pH7.0-7.2, amount of inoculation 2%, amount of load 50 ml(in 500 ml, flask).The final optimized system allowed the yield of Bacillus subtilis B908 to increase from 6.6×109 spores ml-1 to 1.18×1010 spores ml-1 in flask.At last, the optimized technology was applied 2000L fermentation tun production, optimized technology allowed the yield of Bacillus subtilis B908 to enhance by 50%.
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