Effects of pantolactone and butyrolactone on the pleiotropic phenotypes of lon mutants and on thermal induction of the SOS phenomena in a tif mutant of Escherichia coli K12.

Pantolactone and butyrolactone, known to suppress cell filament formation in the lon mutant of Escherichia coli, were found also to be capable of partially correcting other anomalies of the mutant including impaired lysogenization with bacteriophages lambda and Pl and increased synthesis of colanic acid. In contrast to pantolactone, which inhibited thermal induction of cell filament formation and lambda prophage in the tif mutant as previously described, butyrolactone enhanced these phenomena. It was inferred that whereas these substances exert their effects through acting upon the tif-recA protein in the tif bacterium, there is a distinct target for their characteristic actions in the lon mutant.