THE EFFECTS OF DIFFERENT ATMOSPHERIC AIR ENVIRONMENTS ON RECOMBINANT PROTEIN EXPRESSION IN ESCHERICHIA COLI

Abstract

The gram-negative bacterium Escherichia coli is one of the most commonly used organism for heterologous protein expression (Terpe 2006). This microorganism continues to be an attractive system because of its ability to grow rapidly and at high density on inexpensive substrates, its well-characterized genetics, and the availability of an increasingly large number of cloning vectors and mutant host strains (Baneyx 1999). Many different strains, promoter systems, growth mediums, and growth parameters have been studied over the years in order to try and yield the best combination of high cell density coupled with high concentration and solubility of recombinant protein. A 96-well plate or baffled shake flask may be used as the growth vessel if only a small amount of recombinant protein is needed but for larger amounts generally a bioreactor is used. The main advantage of bioreactors is that growth parameters such as agitation, pH, and dissolved oxygen can be more tightly and easily controlled as opposed to 96-well plates or shake flasks, leading to growth and expression optimization. The effects of aeration and oxygen concentration on recombinant protein expression in E. coil have been widely studied with contradicting results. While oxygen has been the most widely studied gas, atmospheric air also contains nitrogen, carbon dioxide, argon, and other trace gases. My study will aim to test different gas concentrations and combinations in order to maximize the growth, expression, and solubility of recombinant protein produced by E. coli.