Answer:
Step-by-step explanation:
Nonpathogenic vibrio cholerae can acquire the cholera toxin gene by
1. being affected by a bacteriophage ( a virus that infects bacteria ) called CTXphi, which carries the gene for cholera toxin (ctx). This is the most common way that vibrio cholerae becomes toxigenic, or able to produce the toxic that causes cholera.
2. Undergoing chitin-induced transformation, which is a process where bacteria can take up DNA from their environment and incorporate it into their own genome. This can happen when vibrio cholerae encounters chitin, a substance found in the shells of crustaceans and insects. If the DNA contains the gene for cholera toxin, vibrio cholerae can become toxigenic.
These mechanisms allow vibrio cholera to evolve and adapt to different environments and hosts, and pose a challenge for the prevention and control of cholerae.