This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Corynebacterium, Subject name: Microbiology
Beta phage is seen in - 
Select and explain. 
A. Bacillus anthracis, B. Corynebacterium diphtheriae, C. Clostridium botulinum, D. Peptostreptococci
B: Corynebacterium diphtheriae
Answer: B: Corynebacterium diphtheriae 
Explanation: Ans. is 'b' i.e., Corynebacterium diphtheriae o The toxigenicity of the diphtheria bacilli depends on the presence in it of corynephages (tox +). Nontoxigenic strains may be rendered toxigenic by infecting them with beta phage or some other larger phage. This is known as lysogenic conversion or phage conversion.