Abstract: Using avirulent Ralstonia solanacearum to produce ‘plant vaccine’ is a novel approach to control bacterial wilt disease. The avirulent strain of R. solanacearum FJAT-aRS01 has higher control effect against bacterial wilt and genetic stability. To further application of this strain, the agents of FJAT-aRS01 were produced by solid-state fermentation using the fibrous residues of Pennisetum giganteum as the main medium, the medium formulation and fermentation conditions were optimized by orthogonal test, and the quality of agents was detected. The optimized solid-state fermentation medium formulation of the strain FJAT-aRS01 was Pennisetum giganteum residues 36.36%, corn flour 27.27%, rice bran 27.27%, and rice husk 9.09%. The optimal fermentation conditions were as follows: inoculum concentration of 15% (10⁸CFU/mL), material to water ratio of 1:0.8, 150 g fermentation materialsper bag and 48 h fermentation time. The aforementioned optimization achieved 1.80×10⁹CFU/g of FJAT-aRS01 bacterial colonies in the solid inoculum, and the content of the nutrient components exceeded the national standard of microbial fertilizers (NY/T 798-2015). The extract solution of FJAT-aRS01 agents with 50 and 100 dilution ratio could promote seed germination of tomato, pepper and eggplant, respectively. Morever, the FJAT-aRS01 agents could improve plant growth when the dosage was less than 15%, and had a control efficiency of above 75% when the dosage was more than 25%. The results indicated that FJAT-aRS01 agents had good application prospect in growth-promoting and disease prevention.

Key words: bacterial wilt, Ralstonia solanacearum, avirulent strain, solid-state fermentation, solanaceous vegetable