You have isolated a strain of brewer’s yeast (Saccharomycescerevisiae) in the lab for your second job at a hip newmicrobrew . You find that this strain ferments more efficiently andadds a superior flavor profile to your brews. You want to clone thestrain of yeast and generate a genomic library to determine thegenes responsible for this finding. To do so you:

1. Obtain fragments of the whole yeast genome (DNA) throughrestriction digestion
2. Open your vector and ligate the DNA fragments
3. Transform E. coli with these vectors
4. Select for E. coli that have obtained vectors
5. Screen for E. coli transformed with recombinant plasmids
6. Obtain recombinant plasmids from the library and transformyeast with them
7. Clone by complementation the gene that can give superiorfermentation.

Note: the cloning site is within the lacZ gene.

a) (3 points) In step 3 you transform E.coliwith your plasmids and plate them on a solid agar medium to growand isolate colonies. What medium should you used to distinguishthe bacteria transformed with recombinant vectors from ones thatcarry non-recombinant vectors? Briefly explain how the mediumallows for you to distinguish. (hint: look up the substrateX-gal)

b) (2 points) You identify a recombinant vectorthat passes your complementation test. You are curious whether thisvector will cause bacteria to ferment sugars for brewing. Provideand explain two reasons why this recombinant vector will NOT workin bacteria.