Biocontrol of phage cocktail combined with bio-organic fertilizer on tomato bacterial wilt

Abstract:

[Background] Previous studies have shown that phage cocktails (multi phage combinations) specifically infecting Ralstonia solanacearum significantly reduce bacterial wilt occurrence. Though bio-organic fertilizer (BOF) can suppress disease incidence of bacterial wilt, its inhibitive effects are not stable due to complex environment in the fields. [Objective] In order to improve biocontrol efficiency of BOF and targeted suppress bacterial wilt, we explored the effect of phage cocktail combined with bio-organic fertilizer fermented by Bacillus amyloliquefaciens on the biocontrol of tomato bacterial wilt. Meanwhile, impacts of this method on the population of R. solanacearum and the bacterial community in the rhizosphere was also investigated. [Methods] BOF obtained by the secondary fermentation of B. amyloliquefaciens T-5 was applied as a base fertilizer in spring in the greenhouse. Phage cocktail which contained four lytic phages of R. soalanacearum were soil-drenched during the flowering period of tomato. The incidences of bacterial wilt and the abundance of R. solanacearum in tomato rhizosphere were measured. Changes of bacterial communities were analyzed via high-throughput sequencing. [Results] Compared with conventional fertilization, the combination of bio-organic fertilizer and phage cocktail (BOF+P) significantly reduce diseased the incidence of tomato bacterial wilt. Beta-diversity was significantly changed after treated with BOF+P, among which relative abundance of Bacteroidetes increased but Gemmatimonadetes reduced. [Conclusion] Phage cocktail combined can improve bio-control efficiency of BOF significantly, which indicates an application potential.

Key words:phage cocktail;bio-organic fertilizer;soil borne bacterial wilt;biocontrol