Specific response of Escherichia coli K12 sfiA mutants to the presence of ethyl ester of N-alpha-palmitoyl-L-lysyl-L-lysine dihydrochloride (PLL) in a nutrient medium.

N-alpha-palmitoyl-L-lysyl-L-lysine dihydrochloride ethyl ester (PLL) in sublethal doses (6--12.5 microgram/ml) inhibits cell division in E. coli K12 strains C600, JM1, and derivatives of JM1 carrying mutations tif-1, tif-1, sfiA, tif-1 sfiB and sfiB in conditions which do not induces SOS functions. Only sfiA mutants divide normally in the presence of PLL. This response enables direct discrimination between phenotypes of sfiA and sfiB and moreover, also the selection of spontaneous mutants sfiA in a tif+ (recA+) genetic background. The PLL mediated inhibition of cell division in tif-1 sfiA double mutants may indicate that the recA gene product plays a role in the restoration of cell division by sfiA.