The Study Of Purification And Pesticidal Application Of The Chitinase Inhibitor Of Acinetobacter Lwoffii ChI-06

The importance of chitinases in the physiological and developmental processes of fungus and insects makes their inhibitors important targets for potential antifungal and insecticidal agents, as well as antimalarial agents.First of all, this study screened a bacterium producing chitinase which was named as Acinetobacter lwoffii ChI-06. The characteristic of enzyme, such as optimum temperature and pH as well as the fermentation kinetics of the enzyme, were studied.Under optimum conditions, a maximum inhibitor activity of 65.42% was observed after 6 days cultivation at 28℃on a 180 r/min shaker in 50 mL of fermentation medium containing peptone 1.0%, yeast 0.2%, glucose 0.5%, NaCl 0.5%, A1(NO3)₃ 0.02%, marine water extraction 3.0% with 6% inoculum's sizes. In the study in a 3 L fermentor, the time course was cut off half to 3 days and the inhibitor activity was achieved 72.60%, which is 10.97% higher compared to the result in flasks. Based on this study, the fermentation in 30 L fermentor was studied also.Preliminary studies showed chitinase inhibitor could be saccharide. After pufication, the purity of the chitinase inhibitor was higher than 99.5%, then the structure of the chitinase inhibitor was investigated. The molecule of the chitinase inhibitor is 385Da.The Drosophila-killing trials were conducted with the control of Allosamidin and Chlorfluazuron. With the dose of 0.01 mmol, chitinase inhibitor could kill 91.67% flies after 3 days cultivation. The composition and effects of the biopesticide were detected. The optimal biopesticide compositon was as following: chitinase inhibitor 0.3%, surfactants 10%, stabilizer 5%, flavourings 0.1%. The LT₅₀ and LT₉₀ were 42.6 and 59.9h.