Question

(a) A group of students are trying to isolate recombinant insulin .After processing the fermentation broth, they observed no yield. What could be the most possible reason for this?

(b) A recently discovered microbial strain gives us the desired metabolite in nanomolar concentration. Suggest two ways of improving the production of the desired metabolite.

(c) Pichia pastoris has many advantages as a eukaryotic expression host. Justify giving two reasons.

Answer 1

(a) Recombinant insulin is an intracellular protein so we need to process the cell mass and not the fermentation broth.

(b) Strain improvement is done in order to maximize metabolite production by:

i) Mutant selection: There are two methods - Physical method & Chemical Method 

ii) Genetic engineering

(c) i) It has strong inducible promoters

ii) It is capable of making post-translational modifications similar to those performed by human cells

iii) Downstream processing is simpler as Pichia does not secrete its own proteins into the fermentation medium.