A genetically engineered protease that can be produced from Escherichia Coli has been developed at Research Genetics. The protease is expressed in E.coli via transformation with a plasmid that contains the protease-encoding and secretion sequences. The protease is excreted out of the cells after completion of the growth phase and the maturation of protease occurs at during the stationary phase. The fermentation process, started in shaker flasks, has been scaled up to 2L and 10L fermenter. Five parameter temperature, pH, dissolved oxygen levels, protease activity and cell density (by optical density of the culture and the cell plating technique) were monitored.The yield of excreted protease activity is increased by increasing the oxygen transport during the latter part of the cell growth phase. The oxygen consumption returns to a low, cell-maintenance level upon completion of the cell growth phase. The increase in excreted activity can be attributed only partially to the increase in cell mass promoted by the increased oxygen transport. Control experiments were conducted to compare the growth rates, dissolved oxygen profiles and protease activity for plasmid containing fermenter runs and plasmid free fermenter runs. This protease has many applications like to process cell lysates for recovery of DNA, and a component in laundry detergents.
My graduate program advisors at UAH: Dr. Douglas Hayes. I would also like to thank Dr. Krishnan Chittur from UAH and Dr.Chris Russell , Dr.Harold Zappe and Mr. Greg Bell of Research Genetics (an Invitrogen Co.) for providing me a great oppurtunity to conduct my research work at their facility.
