Screening, Identification Of Bacillus Spp.Antagonistic To Root-knot Nematodes From Hainan Jianfengling&Jiaxi Tropical Rainforest And The Preliminary Study On Fermentation Process

Root-knot nematode (Meloidogyne spp.) is a kind of plant parasitic nematode, no strict host specificity, can infect a variety of crops, resulting in cuts, and even total destruction, serious damage to agricultural production. At present, chemical pesticides is the main prevention measure, but this approach which have many disadvantages, not only damage the environment, but also endanger human body health, in addition, it is easy to make nematodes produce drug resistance, etc., so the use of chemical pesticides are gradually limited. Biological control for its safe and pollution-free advantages, more and more attention has been paid by people. Bacillus which is widely distributes in nature, diverse genetic types, and can generate strong resistance spores, so it is the key of the root knot nematodes bio-control resources development. On this research, a survey of Bacillus resources from Jianfengling and Jiaxi tropical rainforest of Hainan province is conducted, then the anti-nematode activity strains were screened, finally active strains were identified. The main content of research is as follows:A five-point sampling method was used, and got the surface soil samples from Jianfengling and Jiaxi tropical rainforest. After separation through coating the plate, eliminating duplicate by means of purification and verification via spore-staining,291Bacillus were got in total, which of143from Jianfengling tropical rainforest,148from Jiaxi tropical rainforest.For291strains of Bacillus, the resistance to root knot-nematode is detected. Firstly, The pine wood nematode(Bursaphelenchus xylophilus) as a target,16strains with higher antagonistic activity were obtained, the corrected mortality were all above80%; Then, second instar larvae(J2) of Meloidogyne incognita as a target, strains were obtained from the first screening were rescreened, after fermentation supernatant was diluted10-fold, the correction mortality rates above50%, with the highest activity for the three strains DB13136, DB13170, DB13184, which corrected mortality were63.6%,58.1%,56.7%respectively.Three active strains were identified by training characteristics, morphological characteristics, physiological&biochemical characteristics, and the phylogenetic analysis based on16S rDNA. The strain DB13136eventually was identified as Bacillus cereus, the strain DB13184was identified as Bacillus toyonensis, the strain DB13170was identified as one of Bacillus spp., but the exact taxonomic status pending further analysis.