RUI: Acid and Base Stress in Escherichia Coli

Kenyon College, Gambier OH

Investigators

Abstract

A grant has been awarded to Dr. Joan Slonczewski of Kenyon College to study acid and base stress in the bacterium, Escherichia coli, and to train undergraduate students in microbiological research. Bacteria make different proteins to help them survive extreme changes in pH, both in natural environments and within the human body. For this project (a continuation of MCB-9982437), a model of pH-regulated proteins has been developed. This model predicts that growth in acid leads E. coli to convert its food into alkaline fermentation products, and vice-versa. This model will be tested using two-dimensional gel electrophoresis to observe induction of metabolic enzymes that lead to different end products, which will, in turn, be identified by using high-performance liquid chromatography. In addition, the effects of various acidic and alkaline end products on bacterial metabolism will be studied. Acid and base regulation are important for bacteria to survive in soil and aquatic environments, as well as in the human intestine. E. coli is particularly interesting as a model organism whose genome has been sequenced, and as a "neutralophile," a species that can grow in either acid or base. Many mechanisms of food preservation, such as the use of weak acids benzoate and sorbate, depend on pH; yet increasingly food-borne pathogens are acid resistant. Revealing the mechanisms of response to pH change will help us to better understand its environmental effects, as well as the role of pH in food quality and preservation. Furthermore, understanding of pH and metabolism in bacterial cultures will contribute to biotechnology by helping improve growth conditions for bacterial production. Kenyon College emphasizes undergraduate education, and students will be involved in every aspect of this project as they are trained to perform research experiments in microbiology. Several undergraduates have already been attracted to work on the project, and they are encouraged to pursue careers in science.