Abstract:

This work aims to isolate and screen endophytic bacteria of Polygonatum sibiricum Delar. ex Redoute with antifungal activity,and to lay foundation for exploring bio-control microbial resources and development and utilization of P. sibiricum Delar. ex Redoute. The bacterial strains were isolated from the roots and stems of healthy Polygonatum using conventional separation method,and then screened using the plate confrontation method. The strain with the best activity was identified based on phenotypical and biochemical properties as well as its 16S rDNA gene sequence. The antifungal effect of volatile compounds produced by the strain was measured by plate back-off method,and the inhibitory activity of cell-free fermentation broth to pathogen fungi was measured by agar diffusion method. An endophytic bacterium HJ-12 with broad-spectrum antifungal activity was obtained,and was identified as Brevibacillus brevis. The inhibition rate of HJ-12 to 6 phytopathogens ranged from（18.57±0.25）% to （48.33±0.15）%. The inhibition rate of the volatile compounds produced by HJ-12 was from （21.05±0.17）% to （83.53±0.19）%,and the cell-free fermentation liquid also demonstrated obvious antifungal activity after 2 d fermentation. In summary,the B. brevis HJ-12 presents potential application value in biological control of plant fungal diseases.

Key words: Polygonatum sibiricum Delar. ex Redoute, endophytic bacteria, phytopathogen, antifungal activity