Study of high density Escherichia coli fermentation for production of porcine somatotropin protein.
Recombinant E. coli strains and culture conditions were studied for the fermentation expression of porcine somatotropin (PST) inclusion bodies under the control of a pL promoter. Our objective was to achieve high cell density together with a high level of recombinant protein expression. Improved fermentation conditions included oxygen enrichment, yeast extract (YE) effect, optimal specific growth to switch on gene expression, and feeding strategies. To maintain a low residual glucose concentration, a medium feed rate was controlled on a real-time basis by using cell density information estimated from on-line carbon dioxide monitoring of a fermentor's exhaust gas. The optimal specific growth rate required to initiate a temperature shift in our system was found to be around 0.2 hr-1. The cell density and PST expression level could reach 55 OD600 and 35%, respectively, after 16 hours of cultivation under optimal conditions by applying computer-controlled nutrient feed. In our recombinant host/vector system, the location of cl gene appears to affect gene expression under YE-supplemented and/or a high cell density culture condition. With cl gene placed on plasmid, our E. coli host no longer showed sensitivity toward YE in PST gene expression.
Chang
L L
LL
Development Center for Biotechnology Taipei, Taiwan, Republic of China.
Hwang
L Y
LY
Hwang
C F
CF
Mou
D G
DG
D000818:Animals; D003001:Cloning, Molecular; D003201:Computers; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005285:Fermentation; D015870:Gene Expression; D005822:Genetic Vectors; D013006:Growth Hormone / Q000096:biosynthesis* / Q000235:genetics; D010957:Plasmids; D013552:Swine; D015003:Yeasts
D013006:Growth Hormone