Using Proteome Analysis as a tool in Bioprocess Engineering

Babu Raman and Mark R.Marten
University of Maryland Baltimore County
1000 Hilltop Circle
Baltimore, MD 21250
braman1@gl.umbc.edu
(410) 455-3437

While it is believed that all large scale bioreactors experience some degree of heterogeneity due to improper mixing, few studies have been performed to identify how this affects cellular metabolism. In this study, Proteome analysis was used to understand how E. coli respond to less-than-ideal mixing in bioreactors.

The term "proteome" was first introduced in 1995, and refers to the total protein output encoded by the genome of a cell. Proteome analysis is a two step process that involves the separation and subsequent identification of individual proteins from a cell lysate. Two dimensional polyacrylamide gel electrophoresis (2D PAGE) is used to separate the proteins based on their isoelectric point and molecular weight. Subsequent identification of separated proteins is accomplished with newly developed genome information and analytical techniques involving mass spectrometry.

To study the effects of suboptimal mixing, and resultant transient nutrient environments, on cells, E. coli was grown in a 20 L fermentor, exposing them to two different nutrient environments. The control was a fed-batch fermentation with constant glucose feed. In the second fed-batch fermentation, the feed was added in a pulsed manner to simulate non-ideal mixing environments. 2D gels were run for samples from the two fermentations. Comparison of the gels yielded information on how E. coli responds to transient nutrient environments.