Isolation and characterization of phages infecting Bacillus cereus

Abstract

Aim: To isolate and characterize bacteriophages (phages) that infect the foodborne pathogen Bacillus cereus. Methods and Results: Two phages were isolated from soil based on their ability to form plaques on four indicator hosts including Bacillus thuringiensis subsp. israelensis, and three isolates of B. cereus. The purified phages were characterized by morphology, host range, single‐step growth curves and restriction enzyme digestion profiles. The phages appeared to be of the Myoviridae family based on their structure in electron micrographs. The phages lysed bacteria of several species, produced average burst sizes of 322 and 300 phages per infected cell, and both had genomes over 90 kb. The phages were chloroform‐resistant and stable at 4°C. They reduced the concentration of B. cereus in mashed potatoes by >6 log10 CFU ml−1 within 24 h at room temperature, when applied at a high concentration. Conclusions: The relatively narrow host range within B. cereus might mean that these phages need to be used as part of a ‘cocktail’ of phages for biocontrol, but their efficacy for the control of their host in food was demonstrated. Significance and Impact of the Study: This is the first report of biocontrol by phages of B. cereus in food.

Occurrence of Bacillus thuringiensis and their phages in Yemen soil

“…Results indicated that, phage active against Bt may be present in soil or integrated with host genome (lysogeny) or as independent linear replica within the cell. These results are in accordance with finding of [19,26,27,41,43,48]. Electron microscopic studies of the isolated phages (Fig.…”

“…Morphologically, these four phage virtually did not differ from 8 phages described by Azizbekian et al [11] and phage TB10 described by Ackermann et al [4]. The tail and capsid measured here are totally different from Bacillus cereus phages measured by The morphology of the plaque depends upon the phage, the host, and the growth conditions a At least ten measurements taken directly from negatives Bacillus thuringiensis and their phages 111 [26] Meanwhile, Phage YHS was appeared with very short tail and isometric polyhedral capsid. This phage belonged to the group C1 morph.…”

The Genomes, Proteomes, and Structures of Three Novel Phages That Infect the Bacillus cereus Group and Carry Putative Virulence Factors

“…Cross-infectivity studies of Basilisk, JL, and Shanette were warranted because others have observed cross-infectivity of bacteriophages that infect the Bacillus genus (49)(50)(51) …”

Possible Use of Bacteriophages Active againstBacillus anthracisand OtherB. cereusGroup Members in the Face of a Bioterrorism Threat

“…For example, two phages, FWLBc1 and FWLBc2, which were isolated from soil, reduced the pathogen in mashed potato (by >6 log 10  cfu/mL during 24 h). Because of the phages' narrow lytic activity, it has been suggested to use them as a component of phage cocktails [114]. This high specificity may constitute a disadvantage in using phages against foodborne pathogens, due to the complex composition of bacteria that contaminate food.…”