Control Efficiency of Bio-organic Fertilizers on Tobacco Bacterial Wilt and Their Effects on Soil Bacterial Community

Tobacco bacterial wilt is a severe soil-borne disease.In order to control tobacco bacterial wilt, we isolated and selected Bacillus methylotrophicus strain JK3, B.subtilis strain JK4, and B.amyloliquefaciens strain JK10 which exhibited strong antibacterial activity against Ralstonia solanacearum.Fermentation solutions of these three antagonistic strains were added to organic fertilizers to make bio-organic fertilizers (SF2, SF4).Bio-organic fertilizers were applied to the field to control bacterial wilt.The results showed that after application of bio-organic fertilizers tobacco bacterial wilt was effectively controlled.The control efficiency of SF2 and SF4 treatments were 82.18% and 68.82%, respectively.We analyzed the soil bacterial community through high-throughput sequencing technology.It was found that the soil bacterial community changed dramatically after application of bio-organic fertilizers.Compared to the control, the abundance of beneficial bacteria including Sphingomonas spp., Paenibacillus spp., Thermobacillus spp., and Clostridium spp.significantly increased in the SF2 and SF4 treated soils.Abundance of Streptomyces spp.and Bacillus spp.also increased noticeably after the application of bio-organic fertilizers.Streptomyces spp.and Bacillus spp.might inhibit the growth of R.solanacearum.Our results indicated that bio-organic fertilizers added with antagonistic Bacillus spp.could effectively control tobacco bacterial wilt.