Study Of The Isolation,Identification And Fermentation Conditions Of Anti-fungal Bacillus Subtilis J-2

Being important pathogenic microorganism,fungi are closely related to many severe plant diseases,human and animal diseases and food contamination,thus find and develop new anti-fungal material is important for the control of the pathogenic fungi.Today many microbial organisms were reported to produce antifungal material,so study of finding new antifungal material from microbial sources catchs more and more interest.In this study,we isolated and identified an anti-fungal bacterial strain from deer faeces.The anti-fungal activity under different fermentation conditions of this bacterium was also studied.First,a bacterial strain with strong resistance to various plant pathogenic fungi was isolated from deer faeces.Based on morphological observation,Gram staining,physiological and biochemical tests,and further 16S rDNA sequence homology analysis at the molecular level,this bacterial strain was identified as Bacillus subtilis J-2.Second,agar diffusion method was used to explore the antibiotic activities of B.subtilis J-2’s fermentation supernatant.Results indicated that the fermentation supernatant strongly restrained four strains of phytopathogenic fungi.However,it was ineffective against Canidia Albicans.Finally,series of experiments were performed to investigate the effect of fermentation conditions on the yield of antifungal activity.The single factor experiments indicated that the yield of antimicrobial activity was influenced by fermentation conditions such as nitrogen source,initial pH of the medium,fermentation time,fermentation temperature and shaking speed.In addition,orthogonal experiments were conducted to explore the optimum fermentation conditions.The influence order of the factors was fermentation temperature>fermentation time>stirring speed>initial pH of the medium.The optimal fermentation conditions were that,B.subtilis J-2 was,at the volume ratio of 1:100,inoculated into basic fermentation medium at the pH of 7.0,and fermented for 8h at 35℃,250r/min shaking speed.This paper aims to isolate and identify B.subtilis J-2,and then optimize fermentation conditions to obtain the antimicrobial substances that can effectively restrain several kinds of important phytopathogenic fungi.Importantly,this study provided the theoretical and research basis for the development of environmental,energy-efficient,highly effective biological pesticides and related products.