Isolation and Characteristic of Bacillus Cereus Phage Z3 and Its Application in Rice and Milk

Bacillus cereus is a foodborne pathogen that widely exists in various food products. In this study, a new B. cereus phage, named Z3, was isolated from the soil and characterized. Transmission electron microscopy (TEM) observations revealed that Z3 had an icosahedral head and a retractable tail, belonging to myxovirus . The doublestranded linear DNA of Z3 was 159,116 bp in length with a CG% content of 39.96%. Genomic analysis indicated that Z3 represented a new species belonging to the Caeruleovirus genus. Z3 showed broad lytic spectrum, as it could lyse 10 out of 13 tested strains of B. cereus . The in vitro phage killing assay and the one-step growth curve showed that Z3 could effectively inhibit the bacteria growth within 10 h and it had a short latent period and fast multiplication speed. Besides, stability tests showed that Z3 was tolerant to a wide range of temperature (4 degrees C - 55 degrees C) and pH levels (4 - 10), and was UV-resistant for 100 min. Furthermore, the applications of Z3 in rice and milk demonstrated its effective antimicrobial properties against B. cereus in food matrix. These findings suggested that Z3 may be a promising biocontrol agent against B. cereus in food industry.