Biochemical analysis of galactose induced bacteriostasis in galT mutants of Escherichia coli K 12.

ABSTRACT

Escherichia coli mutants completely defective in galactose- 1-phosphate uridyl transferase (EC 2.7.7.10) and growing in glycerol medium undergo rapid cessation of growth when exposed to galactose. Toxicity due to galactose is equally pronounced when glycerol is replaced by other carbon sources, like succinate and proline. Gas chromatographic analysis failed to detect even trace amounts of galactitol. Moreover, galactose- 1-phosphate had no inhibitory role on some of the critical enzymes of cellular metabolism. General loss of energy (ATP) due to futile phosphorylation of galactose is probably the cause of bacteriostasis. The galT mutants can serve as models of human transferaseless galactosemia only to a limited extent.