title: Study of high density Escherichia coli fermentation for production of porcine somatotropin protein.
abstract: 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.
authors.affiliation: Development Center for Biotechnology Taipei, Taiwan, Republic of China.
authors.forename: L L
authors.initials: LL
authors.lastname: Chang
authors.forename: L Y
authors.initials: LY
authors.lastname: Hwang
authors.forename: C F
authors.initials: CF
authors.lastname: Hwang
authors.forename: D G
authors.initials: DG
authors.lastname: Mou
mesh_terms: 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
chemical_list: D013006:Growth Hormone