Biological control of Ralstonia solanacearum using Ralstonia phage and the influence of diversity of soil bacteria
Tobacco bacterial wilt caused by Ralstonia solanacearum is one of the main diseases of tobacco. Ralstonia phage ∈RS-1 was isolated from the soil of tobacco bacterial wilt nurseries from experimental fields of the Tobacco Research Institute of CAAS Institute, Jimo District, Qingdao City. ∈RS-1 is an obligated parasite of R. solanacearum, and can infect and lyse R. solanacearum cells preventing them from dividing and reproducing and so controlling the disease pandemic. So ∈RS-1 has real potential as a new microbial inoculant on R. solanacearum infected fields. We irrigated the tobacco root with the ∈RS-1 culture (1×1010pfu/mL) before artificial inoculation of R. solanacearum. The result showed a significant decrease in disease severity when R. solanacearum was co-inoculated with ∈RS-1. The control efficiency of ∈RS-1 against R. solanacearum could reach 94.87%, and was higher than control by agricultural streptomycin. Additionally, the diversity of bacterial community in treated soil by ∈RS-1 was studied using metagenomic technique. The result showed that the soil R. solanacearum content is obviously lower than in the untreated control and ∈RS-1 does have remarkable influence to the other microorganisms. In treated soil, the quantity of bacteria showed a descending trend as well as actinomyces compared to the untreated control. So ∈RS-1 has the role of adjusting the diversity of soil bacteria.