AN IMPROVED FERMENTATION PROCESS FOR PRODUCING HIGH LEVELS OF RECOMBINANT HUMAN PROINSULIN IN A METHYLOTROPHIC YEAST

摘要

: The invention relates to fermentation process where in a methylotrophic yeast transformant containing a target gene encoding an insulin precursor (proinsulin) is used. The recombinant yeast is grown in two phases comprising of a batch and fed-batch modes to a high cell density culture using a synthetic medium containing glycerol as the sole carbon source. The high cell density culture is subjected to induction using methanol as the sole carbon source along with different nitrogenous supplements and variation in process parameters for enhancement of proinsulin expression level as extracellular product into fermentation media. The increase in pH of the culture medium prior to and during induction of the methanol responsive promoter improves yield of proinsulin expression. A fermentation process that gives high yields of proinsulin without using pure oxygen has also been described. A downstream process involving treatment with charcoal of the culture broth containing proinsulin to remove the pigment has also been described. No. of Pages : 22 No. of Claims : 29