Potential of bacteriophage PCT27 to reduce the use of agrochemicals to control Pectobacterium carotovorum subsp. Carotovorum in Chinese cabbage (Brassica pekinensis)

As antimicrobial resistance (AMR) continues to spread among bacteria and poses a serious threat to global health, the indiscriminate use of antibiotics in various fields, including agriculture, should be avoided. Here, we isolated a novel bacteriophage (phage), PCT27, specific for Pectobacterium carotovorum subsp. carotovorum (Pcc), a phytopathogen responsible for soft rot of crops, and investigated its potential as an adjunct to reduce the use of agrochemicals in Pcc control. Phage PCT27, which belongs to the family Autographiviridae, inhibited in vitro growth of Pcc within 1 h of infection by recognizing colanic acid as a host receptor. More than 90% of the virions rapidly adsorbed to the host cells within 3 min, supporting the efficient control of Pcc by PCT27. PCT27 supplementation reduced the minimum inhibitory concentration of streptomycin by 50% for Pcc control in vitro. Accordingly, PCT27 successfully complemented an antibiotic-based agrochemical in preventing Pcc infection in Chinese cabbage leaves and seedlings by reducing the dose of the agrochemical by a quarter. As a biocontrol agent for Pcc that complements agrochemicals, PCT27 can not only prevent economic losses due to crop decay but would also contribute to addressing the AMR crisis for sustainable agriculture and environmental safety.