Non-toxigenic C. diphtheriae changes to toxigenic C. diphtheriae with the help of bacteriophage ,by which method this conversion occur?
**Core Concept**
The conversion of non-toxigenic Corynebacterium diphtheriae to toxigenic C. diphtheriae involves the acquisition of the toxin gene, which is mediated by a bacteriophage. This process is known as lysogenic conversion.
**Why the Correct Answer is Right**
The toxin gene, specifically the diphtheria toxin gene (tox), is carried by a temperate bacteriophage called corynephage β. When this phage infects the non-toxigenic C. diphtheriae, it integrates its genetic material into the bacterial genome through a process called lysogenic conversion. This integration leads to the production of diphtheria toxin, making the bacterium toxigenic.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct mechanism of conversion. While conjugation is a method of gene transfer, it is not the primary mechanism involved in the conversion of non-toxigenic to toxigenic C. diphtheriae.
**Option B:** This option is incorrect because transformation is the process of direct uptake of free DNA from the environment, which is not the mechanism by which the toxin gene is transferred to C. diphtheriae.
**Option C:** This option is incorrect because transduction is the process of gene transfer mediated by a bacteriophage, but it specifically refers to the transfer of bacterial DNA from one bacterium to another, rather than the acquisition of a toxin gene.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the conversion of non-toxigenic to toxigenic C. diphtheriae is a rare event, but it can occur when the bacterium is exposed to a temperate bacteriophage carrying the toxin gene.
**Correct Answer: C. Transduction.