Mutants of Aerobacter aerogenes blocked in the accumulation of inorganic polyphosphate.

SUMMARY Mutants of Aerobacter aerogenes blocked in the accumulation of inorganic polyphosphate were isolated by the following method. Organisms previously subjected to ultraviolet (u.v.) irradiation were induced to accumulate polyphosphate in medium containing 32P. Upon subsequent growth in medium devoid of phosphate, RNA and DNA synthesis took place at the expense of polyphosphate. The organisms containing radioactive DNA were inactivated by decay of the 32P during prolonged cold storage. From the survivors, mutants unable to form volutin granules were selected by microscopic examination. The mutants fell into two classes. The majority did not accumulate polyphosphate when phosphate was added to a phosphate-starved culture, but did so upon prolonged sulphur starvation. The remainder of the mutants did not accumulate polyphosphate under either condition. Both kinds of mutant grew well in a defined medium and showed no obvious physiological disabilities.