Isolation and Characterization of Mutants of Escherichia coli with Cellular Division Selectively Affected by Growth on Fatty Acids

Isolation and characterization of mutants of Escherichia coli that beta-oxidize fatty acids at normal rates, but which divide very slowly when grown on fatty acids, are described. These mutants grow normally on other carbon sources. By growth on oleate, experiments with radioactive precursors showed that the rates of incorporation into ribonucleic acid, protein, and cell wall were comparable to those observed with the parent, whereas the rate of incorporation into phospholipids was slightly decreased. Under these conditions the rate of incorporation of ³²P-orthophosphate into deoxyribonucleic acid was low. On the other hand, by growth on oleate, neither gross mass increase in the different macromolecules nor loss of viability was observed, whereas in the presence of inducer the derepression of the lac operon enzymes occurred. Therefore, extensive turnover of the macromolecules is involved when these mutants are grown on fatty acids. Studies of the crypticity and of the binding of 1-anilino-8-naphthalene sulfonate show differences in membrane structure between the mutants and the constitutive parent. Properties of these mutants, which are affected in the process of cellular division, are discussed.