An oil eating bacteria: Pseudomonas capacia, P. putida and other spp. Acinetobacter sp. Efficient degraders have been prepared through genetic
engineering and they need to be established in the environment at a required density.
Production of Human Insulin (Humulin): Human insulin is a dimer comprising one chain of 21 amino acids (A chain) and the other of 30 amino acids (B chain), the C chain that links A and B chains. Chains A and B become linked by two disulphide bridges. This is followed by cleavage of the leader and the C chain sequences leaving the mature insulin molecule. Insulin is the first genetically engineered hormonal drug ever marketed anywhere in the world. It was produced first in 1980 by Eli Lilly (U S A.) with the name Humulin by transferring the insulin gene into E.coli.
The genes (= DNA sequences) for chains A and B of insulin were synthesized separately as early as 1978. The genes for A and B chains were integrated separetely in pBR322 type vector. The purified chains A and B were then attached to each other by disulphide bonds induced in vitro; this, however turned out to be an inefficient reaction. Subsequently, a gene representing B, C and A chains was synthesized and expressed in E. coli; in this case, the intervening chain is removed proteolytically following spontaneous folding of the proinsulin molecule.
