Screening Of Marine Actinomycetes With Nematicidal Activity And Identification Of Strain HA07011

In this paper, 256 marine actinomycetes strains were isolated from 21 marine environment samples, such as seaweed mud, mangrove sediments and sponges in Hainan and Zhanjiang. The fermentation broths were tested for knockdown efficiency against nematodes, and the strain HA07011 with higher nematicidal activity was identified. The major results as followed:We got a large number of target nematodes (Bursaphelenchus xylophilus), which were cultured with Fusarium sp.. After cultured 5 days at 28℃, the density was about 200 individual per cm2. Through 24 well-plate assay, 23 active actinomycetes strains of knockdown against B.xylophilus were obtained. All of the fermentation broths had more than 80% knockdown efficiency after 24h. When the fermentation broths were diluted 5-fold, the strains HA01110,HA01125 and HA07011 had the highest knockdown efficiency 67.1%, 72.0% and 84.3%, respectively.Action mode of the 3 actinomycetes strains against B.xylophilus was explored. Fermentation broths of HA01110 and HA01125 knocked down 90%-100% of the nematodes within 8h, most recovered movements in fresh water; 33.8% and 17.2% of B.xylophilus could still recover within 24h. HA07011 could completely knock down all the B.xylophilus within 8h, but most recovered their movements in fresh water; no recovery was observed within 24h.Furthermore, the knockdown efficiency to tomato root-knot nematodes were tested. The results showed that their 5-fold diluted fermentation broths had more than 70% revised knockdown rate, especialy HA07011. After subculture of 5 cycles, the results showed that strain HA07011 still keeped the ability of producing nematicidal compounds.By studying the morphology, cultural characteristics, physiological and biochemical propertices, 16S rDNA and phylogenetic tree, HA01041 was identified as Streptomyces griseoincarnatus HA07011。...