Decoding the biocontrol potential of C22 phage: A natural solution to bacterial wilt disease

Abstract

Ralstonia solanacearum species complex (RSSC) causes bacterial wilt disease in major crops worldwide. As naturally occurring bacterial predators, bacteriophages (phages) offer a promising and environmentally friendly alternative to chemical pesticides. Understanding phages in-depth is needed for effective phage use in integrated pest management. In this study, we characterized a novel phage, C22, isolated from soil in Chiang Mai, Thailand, for its potential as a natural biopesticide against RSSC. The C22 phage is novel and capable of lysing Ralstonia solanacearum (Rs). The phage genome length is 43,284 base pairs (bp). We annotated 57 proteins, with 27 matching phage proteins with known functions or features. We found three closely related isolates, including the RpY1 and DU_RP_II phages infecting Ralstonia spp. and the Ensifer adhaerens isolate ST2 prophage. Together with the C22 phage, they potentially belong to a novel genus based on genomic and proteomic analyses. We evaluated its properties as a biocontrol agent. C22 phage has a wide host range, a burst size of 427 PFU per cell, and is highly stable at 20–50 °C, pHs 5–11, and 10–50 mM MgSO₄, making it an attractive choice for biocontrol utilization. These findings support the potential of C22 as a natural pesticide for bacterial wilt management and provide a foundation for phage formulation, storage, and integration into pest management strategies.