Study On Risk Assessment And Control Technology Of Bacillus Cereus From Meat And Meat Products

Bacillus cereus(B.cereus)is one of the foodborne pathogens.Till date,the risk investigation of B.cereus in foods is mainly focusing on local areas in China.It is therefore necessary to perform national wide surveillance to provide fundamental data for evaluating the safety risk of B.cereus.In addition,a new prevention and control technology of B.cereus can be developed on this basis.This study analyzed the contamination,virulence gene detection rate and antibiotic susceptibility of 603 B.cereus in meat and meat products collected from 39 major cities in China during 2011-2016,and assessed the potential hazards of the isolates.The genetic diversity of the isolates was characterized by enterobacterial repetitive intergenic consensus-PCR(ERIC-PCR)and multi-locus sequence typing(MLST)methods.A novel biological control and prevention technology based on phage and its endolysin was developed.The contamination rate of B.cereus in meat and meat products in China was 27.03%.The detection rate of enterotoxin-encoding genes was up to 99%.All isolates were multi-drug resistant,and 99.4% of isolates resisted to 5 or more antibiotics.Both ERIC-PCR and MLST molecular typing indicated that the B.cereus isolates in meat and meat products were with high genetic diversity.Therefore,B.cereus in meat and meat products in China has a certain level of risk to induce diseases.Three new B.cereus specific phages were isolated from water and sludge near the Pearl River in Guangzhou,whose genomes contain endolysin encoding genes,named LDK1,LDK2 and LDK3.The purified LDK2 had a more bactericidal effect and a broader host spectrum than phage DK2,which may be a promising alternative antimicrobial for the treatment of pathogenic B.cereus infection.