Isolation and characterization of Bacillus cereus virulent phage CA1

Abstract

Infection of Bacillus cereus can lead to massive mortality of Chinese soft- shelled turtles (Pelodiscus sinensis). Phage has shown promising effects in the treatment of bacterial infections. A virulent phage CA1 was obtained from pond water of a P. sinensis aquaculture farm. The characteristics of CA1 and its protective effect on P. sinensis were analyzed, and whole genome were sequenced. The phage CA1, with a long tail and a hexagonal head could specifically lyse B. cereus. The CA1 latent phase was 40 min, and the rise phase was 40–160 min. The optimal growth temperature for CA1 was 45 °C, the optimal pH was 7.0, and the multiplicity of infection (MOI) was 0.1. Its whole genome was 45,902 bp linear double-stranded DNA molecule with an average GC of 38.30%, and contained 74 predicted open reading frames. After infection of P. sinensis with B. cereus (1.0 × 107 CFU/g), the protection rate was 54% at the phage MOI of 0.1. The above findings demonstrate that CA1 exhibits typical traits of phage-based disinfectants, suggesting its potential application in the prevention and management of B. cereus contamination within aquaculture environments.