Isolation and characterization of virulent bacteriophages infecting Bacillus cereus

Bacillus cereus causes food borne illness with diarrheal and emetic syndromes and other non 
gastrointestinal infections. Bacteriophage is considered as an imperative biocontrol agent to 
eliminate the growth of deleterious microorganisms. In our study, B. cereus ATCC 33013 was used 
as a representative B. cereus for phage isolation. Four B. cereus phages (BCP1, BCP2, BCP3 and 
BCP4) were isolated from 62.5 % from tested clay soil samples. According to the phage 
morphology, three phages (BCP1, BCP2 and BCP4) are belonging to Siphoviridae, but BCP3 
belongs to Myoviridae. The genome size of the four isolated phages ranged between 28.7 and 33.6 
kbp. All phages had lytic activity against only Bacillus thuringiensis which was tested with other 
eight Bacillus spp. to determine the host range. SDS-PAGE analysis revealed that only one phage, 
BCP3, had five protein bands with molecular weights ranging from 37.0 to 110.0 kDa. The effect of 
UV, temperature and pH on the lytic activity of BCP1 was evaluated. BCP1 retained 58.7% of 
activity after 75 min exposure to UV light. Conversely, it lost 72.5 and 18.1% of activity after LTLT 
and HTST pasteurization, respectively, and lost whole activity after boiling for 10, 20 and 30 min. 
BCP1 was sensitive to extreme acidic and alkaline conditions as its activity was completely lost at 
pH 1.0, 3.0 and 13.0.