Effects of cobalt (III) complexes on growth and metabolism of Escherichia coli

Inhibition of cell division of E. coli—with the production of elongated cells—was accomplished by incorporating various cobalt(III) complexes, such as chloropentaamminecobalt(III) chloride or nitropentaamminecobalt(III) chloride in a defined growth medium. Studies of cell metabolism and growth rates were undertaken in an attempt to elucidate this phenomenon. Treated cells exhibited stimulated oxygen uptake, but the growth, as reflected by light scattering at 540 nm, was slightly repressed. The results of C-14 glucose tracer studies indicate an enhanced turnover of substrate but do not reflect major shifts in cell biochemistry. Tritiated precursors were used to examine the influence of these compounds on nucleic acid synthesis, and a depression in the incorporation of thymidine-methyl-H-3 into DNA was noted. In contrast to the behavior of the active cobalt (III) complexes, typical cobalt(II) salts, such as cobaltous sulfate, caused complete inhibition of biological activity.