Characterization of LysPBC4, a novel Bacillus cereus-specific endolysin of bacteriophage PBC4

Bacillus cereus is a spore-forming, Gram-positive bacterium, and is a major food-borne pathogen. A B. cereus -specific bacteriophage PBC4 was isolated from the soil of a stock farm and its genome was analyzed. PBC4 belongs to the Siphoviridae family and has a genome consisting of 80,647-bp-long double-stranded DNA including 123 genes and two tRNAs. LysPBC4, the endolysin of PBC4, has an enzymatically active domain (EAD) on its N-terminal region and a putative cell wall binding domain (CBD) on its C-terminal region, respectively. Although the phage PBC4 showed a very limited host range, LysPBC4 could lyse all of the B. cereus strains tested. However, LysPBC4 did not kill other bacteria such as B. subtilis or Listeria , indicating that the endolysin has specific lytic activity against the B. cereus group species. Furthermore, LysPBC4\_CBD fused with enhanced green fluorescent protein (EGFP) could decorate limited strains of B. cereus group, suggesting that the LysPBC4\_CBD may be a promising material for specific detection of B. cereus .