Antagonistic Mechanisms and Related Properties of Strain H5 Against Black-rot Disease of Dracaena sanderiana

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.

Key words:Bacillus licheniformis, Mangrove bacteria, Antagonistic mechanism