Biological characterization and genome sequence of a bacteriophage strain Bac-S infecting Bacillus subtilis

Abstract:

[Objective] The application of Bacillus subtilis in soil can promote plant growth, while few studies have reported the bacteriophages infecting B. subtilis. Therefore, the isolation, biological characterization, and genome sequencing of bacteriophages infecting B. subtilis from soil will contribute to the application of B. subtilis and enrich the biological information of bacteriophages infecting B. subtilis. [Methods] B. subtilis SM13 was used as the host to isolate a bacteriophage strain Bac-S from soil. Biological characterization, whole genome sequencing, gene function annotation, and phylogenetic analysis were performed for this bacteriophage strain. [Results] Transmission electron microscopy showed that Bac-S had a head with the diameter of about 43 nm and a tail too short to be measured. The optimal multiplicity of infection of Bac-S was 0.1. The one-step growth curve showed that Bac-S had an incubation period of about 10 min and a burst size of 30 PFU/cell. Bac-S had a wide host spectrum and can infect hosts of different genera. The sequencing results showed that the genome of Bac-S was 150 019 bp, with the G+C content of 42.6% and 237 open reading frames (ORFs). The BLASTn comparison with the sequences in the NCBI database showed that Bac-S was similar to other bacteriophages infecting B. subtilis. [Conclusion] A bacteriophage strain infecting B. subtilis with a short incubation period, a wide host spectrum, tolerance to high temperature, and intolerance to UV light was isolated from soil. The biological and genetic characterization of this bacteriophage enriches our knowledge about the bacteriophages infecting B. subtilis.