The present study, have undertaken the cloning of bovine growth hormone or bovine somatotropin gene from local cows breed in Basrah city, and optimizing the conditions for its high-level expression in Escherichia coli. To achieve this goal the cDNA for bovine growth hormone was inserted in to the Pst1 site of pBR322 via the poly dC: poly dG joining technique to produce the recombinant vector. The cloning vector was then transformed into E. coli HB101. The efficiency of transformation also determined to be 2 × 107 cfu/µg. The fermentation strategy for high cells density growth of E. coli harboring the bGH gene was carried out and the highest cells density level was determined to be 1.540 ¬¬¬at OD600 after 8 hs of cells growing. Following solubilization and refolding, bovine growth hormone was purified by using ion exchange chromatography and the result was a single visible band with 22KDa on 12% SDS-Polyachrylamid gel which represents the purified bGH.
Key words: Bovine Growth hormone, Recombinant bovine somatotropin, milk, cow reproduction
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