You perform a generalized transduction experiment where phag

You perform a generalized transduction experiment, where phages are collected from an S. aureus donor strain of genotype abc+ def+ ghi+, then used to transduce a recipient of genotype abc- def- ghi-. The recipients were plated on minimal medium supplemented with def and ghi. You see lots of colonies.

1) List the genotypes found in the colonies

2) Colonies are replicated onto three different media, (1) minimal plus ghi only, (2) minimal plus def only, (3) minimal. In theory, what genotypes would grow?

3) Growth was observed at 58% on medium 1, 7% growth was observed on medium 2, and no colonies observed on medium 3. What are the genotypes of the colonies on each medium?

Solution

Generalised transection: When a phage infects bacteria, bacterial genome undergoes fragmentation and few fragments of genome got packed in phage head. After bacterial cell lysis; these phages with bacterial genome transfer the gene to the other bacteria is called Generalised transection:

1) List the genotypes found in the colonies: The possible genotypes of the colonies will be 1. (ghi+ def-), 2. ( def+ ghi-), 3. (ghi+ & def+), 4. (ghi- & def-)

2) Colonies are replicated onto three different media, (1) minimal plus ghi only-(ghi+ def+), def+ ghi-) (2) minimal plus def only- (ghi+ & def+), (ghi+ def-) (3) minimal-(ghi+ & def+). In theory, what genotypes would grow?

3) Growth was observed at 58% on medium 1 -(ghi+ def+), def+ ghi-) , 7% growth was observed on medium 2 (ghi+ & def+), (ghi+ def-), and no colonies observed on medium 3 ((ghi- & def-), def+ ghi-), (ghi+ def-)   ).