Studies On The Microwave Sterilization For The Solid Medium Of Metarhizium

At present, method of sterilization is high pressure sterilization which is time-consuming and can't be operated continuously.In this paper, Bacillus subtilis var.niger (ATCC9372) spores were used as bioindicators.Solid medium were sterilized by microwave generated by household microwave oven whose the output is 800w or in company with hydrogen peroxide.Effect factors and sterilization results were researched.This paper investigated the quality of the solid medium treated with microwave or in company with hydrogen peroxide by the means of inoculating and cultivating Metarhizium anisopliae.This paper is the reference to the industrialized operation of microwave sterilization.(1) Microwave sterilization for the solid mediumDifferent load conditions, moisture levels and soakage were investigated. The results indicated that when microwave sterilization for the solid medium of Metarhizium anisopliae, sterilization rate decreased with the increase of load;moisture level and soakage effected the sterilization results observably.The best technics were 100g solid medium and 60g water were treated with microwave 150s and sterilized entirely after 3 hours soakage before microwave sterilization.(2) Microwave sterilization for the solid medium in company with hydrogen peroxide Soakage,the concentration of hydrogen peroxide, the proportion of stuff to water and time ofmicrowave radiation were researched when microwave sterilization in company with hydrogen peroxide.Arranged the experiments using the L₈ (2⁷) orthogonal experiment.The results indicated that the best technics were l00g solid medium with 60g water, 1.0% (w/w) hydrogen peroxide,3 hours soakage and treated 90s by microwave.(3) Effects of the microwave sterilization for solid cultureInoculating and cultivating Metarhizium anisopliae on the solid medium after sterilization, the quantity of Metarhizium anisopliae conidia per gram solid medium was used as the index and researched the effects of the microwave sterilization on the solid medium. The results indicated that cultivating Metarhizium anisopliae on the solid medium after sterilization, there was no difference in the quantity of Metarhizium anisopliae conidia between the best technics and high pressure sterilization. Metarhizium anisopliae could grow well on the solid medium when treated with microwave 120 seconds or 90 seconds in company with 1.0% hydrogen peroxide.