Antagonistic Mechanisms and Related Properties of Strain H5 Against Black-rot Disease of Dracaena sanderiana / 微生物学通报

ABSTRACT

A strain no.H5 isolated from Rhizophora stylosa Griff in Zhanjiang had a good antagonistic activity against Aspergillus niger,pathogen of Dracaena Sanderiana black-rot disease.It was identified as Bacillus licheniformis.Dual culture,mycelium growth rate and inhibitory zones were used to test the effect. Strong inhibition was shown against A.niger.Inhibitory ratios of H5 germ-free fermented filtrate on mycelium growth and conidial germination were 91.9%and 100%respectively.In addition,mycelia on the edge of antagonistic band became abnormal and over-branching.Meanwhile,a lot of vesicles appeared on the surface.When treated with heat,acid and alkali,the filtration of H5 was always with stable activity.Precipitate in 55%saturated ammonium sulfate dissolved in phosphate buffer solution maintained most of the activity after high pressure steam sterilization for 25 minutes.It was preliminarily considered as a kind of heat resistant protein.