Some physiological characteristics of a phosphate-removing bacterium, Microlunatus phosphovorus, and a simplified isolation and identification method for phosphate-removing bacteria

Some physiological characteristics of a phosphate (Pi)- removing bacterium, Microlunatus phosphovorus, are investigated using aerobically grown cells and cells exhibiting excess Pi accumulation (EPA) in order to determine a simplified isolation and identification method for other Pi-removing bacteria. Such a method would save on the amount of sterile equipment needed, and reduce the number of experimental steps and labor time. The EPA activity of the isolate reached a plateau 13 hours into the anaerobic incubation time, but it reached 70% of that level after only 5 hours. The EPA activity of the cells during the stationary growth phase was higher than that during the exponential growth phase. Polyphosphate (polyP) accumulated in the cells was shown to be used as an energy storage material (a phosphagen) under both aerobic and anaerobic conditions. During aerobic starvation, the rate of decrease in the ATP concentration of the suspension of cells that contained polyP was markedly less than that of the suspension of cells without polyP. Therefore, bacterial cells rich in polyP survive longer than bacterial cells lacking polyP. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.