Study On The Antifungal Substance Of Bacillus Amyloliquefaciens

Biocontrol strain TJ which screened from cucumber soil in Tianjin showed broad spectrum antagonism to phytopathogenic fungi.The TJ strain is powerful in inhibiting melon powdery mildew,with control effect 95.7 %.In this study,the antifungal ability of bacteria TJ was detected.TJ was identified by morphological,physiological,biochemical and phylogenetic analyses.The antifungal protein produced by TJ was purified and its characteristic was studied.The TJ strain can produce some volatile organic compounds(VOCs)with antifungal ability.Meanwhile,we researched the composition and antifungal activity of the VOCs.The main results and conclusion are as follows:Strain TJ can inhibit the growth of Valsa ceratosperma?Glomerella cingulata?Macrophoma kuwastsukaii ? Fusarium oxysporum ? Colletotrichum gloeosporioides ?Penicillium expansum?Botrytis cinerea?Coniothyrium fucsidulum?Phyricularia grisea?Phytophthora capsici?Fusarium proliferatum?Gibberrella zeae?Gaeumanomyces graminis?Colletotrichum graminicola ? Rhizoctonia cerealis.In combination of morpholo gical,physiological,biochemical and phylogenetic analyses,strain TJ was classified as Bacillus amyloliquefaciens.The protein is one of the main antifungal substances in the secondary metabolites of strain TJ.The protein could be obtained with ammonium sulphate at 80 % saturation.Crude protein produced by strain TJ was not sensitive to high temperature,acid and alkali,ultraviolet,protease,methanol,trichloromethane.The avtive substance was detected by LC-MS after purified by DEAE-cellulose and CM-cellulose.The results showed that it contains one antimicrobial peptide,seven uncharacterized proteins,fibrinolytic enzyme,general stress protein and other 25 peptides.The VOCs of B.amyloliquefaciens TJ can inhibit the growth of Valsa ceratosperma?Botrytis cinerea?Alternaria?Coniothyrium fucsidulum?Fusarium oxysporum?Colletotrichum gloeosporioides?Gibberrella zeae?Setosphaeria turcica ?Fusarium oxysporum.Mamy different kinds of VOCs were identified by GC-MS,such as benzene,alkanes,alkenes,furans,alcohols,acids,ketones,esters and so on.4-ethylphenol,2-ethyl-cyclohexanone and trans-2-Nonenal have strong inhibitory ability to V.ceratosperma.