Question

1. Some Escherichia coli strains express an extra superoxide dismutase enzyme, which protects the cell from oxidative damage. Researchers have hypothesized that the genes encoding this enzyme are part of a bacteriophage genome.

1. What is the explanation for E. coli strains being able to express a bacteriophage gene and use its product to their advantage

2. How would you test the hypothesis that sodC is indeed bacteriophage encoded?

Answer 1

The viruses which infect bacteria are called bacteriophages. Given that some Escherichia coli strains express an extra superoxide dismutase enzyme, which protects the cell from oxidative damage.

(a) The explanation for E. coli strains to be able to express a bacteriophage gene and use its product to their advantage is that bacteria might be attacked by bacteriophages via transduction. This process may transfer genes from phage to bacteria, which may get incorporated into the genome of bacteria. Thereafter, bacteria can use the product of a beneficial gene, like sodC, for protection.

(b) We can check whether the genes are encoded by bacteria or phage by analyzing the nucleotide sequence of that gene. We can then determine whether the sequence is phage like or bacteria like.

Another way to test this hypothesis would be to check for the transmission rate of such a gene among bacteria itself, and then locating the position of that gene on chromosome.