Isolation, detection and inactivation of a Myoviridae bacteriophage infecting Bacillus amyloliquefaciens FB11

Bacillus amyloliquefaciens is commonly used as a starter culture for fermentation of soybeans and soybean meals. Like other starter cultures, B. amyloliquefaciens FB11 faces threats from phage infection. Frequent phage attacks during large-scale cell culture cause serious yield losses. To alleviate this problem, phage detection, identification and inactivation are required. The isolation and preliminary characterization of a phage designated BA01 revealed that it is a Myoviridae phage, with some regions of its genome sharing sequence similarity with the genome of Bacillus subtilis phage SPO1. BA01 showed strong lytic activity against B. amyloliquefaciens, B. circulans and B. pumilus. A PCR-based method was developed to detect BA01 in large-scale cell culture of B. amyloliquefaciens FB11, where a pair of degenerate primers could detect BA01 with a limit of detection of 104 PFU/mL. Inactivation of BA01 was achieved by either thermal treatment at 70 °C for 5 min or treatment with peracetic acid-based disinfectant (0.3 % v/v) for 5 min.