| Summary: | 碩士 === 國立中興大學 === 化學工程學系所 === 100 === In recent years, microbial pesticides for biocontrol control has become the goal of agricultural development. In this study, the production of biosurfactant by Bacillus mycoides NP02 under peptone-based medium was found to reached 71.27±1.93 mg/l.
Various types of additives were added into main culture. It was observed that corn oil could reduce the broth tension to 33 mN/m with peptone-based medium, and its biosurfactant production could reach 1744.81±144.89 mg/l, which was approximately 20-fold to that of the control. This result demonstrates oil addition to medium in submerged culture could enhance the biosurfactant production. The biosurfactant produced by B. mycoides NP02 was analyzed with HPLC, and its retention time of 14.6 min is different from that of the surfactin standard. This unknown biosurfactant in broth is expected to be a surfactin isoform, which need further identification.
On the other hand, the optimizing medium enhanced biosurfactant production by Bacillus subtilis CWS1. In carbon source study, sucrose gave the best biosurfactant production, reaching 2283.09±86.85 mg/l. In nitrogen source study, ammonium sulfate was identified to be the most favorable source for biosurfactant production, reaching 2613.16±49.69 mg/l. In the medium optimization, carbon source, nitrogen source and corn oil were chosen as designing factor. According to the response surface methodology, the optimal concentrations of sucrose, ammonium sulfate and corn oil were 50 g/l, 3 g/l and 5 g/l, respectively, where the best biosurfactin production reached 8057.57 mg/l.
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