Catabolite repression

Gene

Propionate

Biology

lac operon

Chromatography

Biochemistry

Physical chemistry

Sodium propionate

Sodium acetate

Mutant

Escherichia coli

Chemistry

Gene expression

Applied and Environmental Microbiology

ABSTRACT In its natural environment, Escherichia coli is exposed to short-chain fatty acids, such as acetic acid or propionic acid, which can be utilized as carbon sources but which inhibit growth at higher concentrations. DNA microarray experiments revealed expression changes during exponential growth on complex medium due to the presence of sodium acetate or sodium propionate at a neutral external pH. The adaptive responses to acetate and propionate were similar and involved genes in three categories. First, the RNA levels for chemotaxis and flagellum genes increased. Accordingly, the expression of chromosomal fliC ′-′ lacZ and flhDC ′-′ lacZ fusions and swimming motility increased after adaptation to acetate or propionate. Second, the expression of many genes that are involved in the uptake and utilization of carbon sources decreased, indicating some kind of catabolite repression by acetate and propionate. Third, the expression of some genes of the general stress response increased, but the increases were more pronounced after short-term exposure for this response than for the adaptive response. Adaptation to propionate but not to acetate involved increased expression of threonine and isoleucine biosynthetic genes. The gene expression changes after adaptation to acetate or propionate were not caused solely by uncoupling or osmotic effects but represented specific characteristics of the long-term response of E. coli to either compound.

DNA Microarray Analyses of the Long-Term Adaptive Response of<i>Escherichia coli</i>to Acetate and Propionate

DNA Microarray Analyses of the Long-Term Adaptive Response ofEscherichia colito Acetate and Propionate