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I got this question:

Diphteria toxin is produced only by those strains of C. diphtheria that have which of the following characteristics?

  1. Encapsulated
  2. glucose fermenters
  3. lysogenic for b-prophage
  4. only mitis-strains
  5. sucrose fermenters

I think the right answer is lysogenic for b-prophage, since Freeman found out that toxic gene is encoded by lysogenic phage infecting all toxigenic strains in 1951. However, I am not sure what "b-" means in "b-prophage".

Which part is "b-" in Prophage?

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up vote 2 down vote accepted

Real simple: Beta! Often called "phage beta" b-prophage is a more modern way to write it. I knew that one off the top of my head, but I like to refer the general public interested in bacteriology to Tadar's online text.

It's nicely done, and I wish that it had been around when I was studying bacteriology.

Specific to your question:

Hence, Corynebacterium diphtheriae can only produce the toxin responsible for the disease if it carries a temperate virus called phage beta. Only lysogenized streptococci produce the erythrogenic toxin (pyrogenic exotoxin) which causes the skin rash of scarlet fever; and some botulinum toxins are synthesized only by lysogenized strains of C. botulinum.

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