Biocontrol efficiencies and identification of nematicidal metabolite from strain BJLSH9 towards nematode and Phytophthora nicotianae
BJLSH9, an actinomycete exhibiting both nematicidal and antifungal activities, was isolated from rhizospheric soil of willow in Beijing. Bioassay results in vivo showed that BJLSH9 displayed a 50.05% efficiency to suppress radial growth of Phytophthora nicotianae, and 98.05% of nematicidal activity towards Panagrellus redivivus at 48 h. In a 40 L – fermenter with medium of No. 38, 72 h of culture period was optimal to obtain the highest mycelial biomass and nematicidal efficiency. The BJLSH9 was identified as Streptomyces flavofungini based on phylogenetic analysis of its 16S rRNA gene. Tryptophandehydrobutyrine diketopiperazine (TDD), a nematicidal secondary metabolite of BJLSH9, was identified and showed 40% nematicidal activity at 48 h. This is the first report on the nematicidal nature of S. flavofungini and TDD.