Chromosomal mutation for citrate utilization by Escherichia coli K-12

Abstract

A mutant strain of Escherichia coli K-12 that utilizes citrate as a sole source of carbon and energy was isolated. Citrate utilization arose as the consequence of two mutations in genes citA and citB, which are linked to the gal operon. The mutant strain expresses a semiconstitutive citrate transport system, and it utilizes both citrate and isocitrate as carbon and energy sources. It is capable of utilizing cis- and trans-aconitate, but only if it is preinduced by growth on citrate.