PHOSPHORUS COMPOSITION AND RELEASE IN SEDIMENT BACTERIA OF THE GENUS PSEUDOMONAS DURING AEROBIC AND ANAEROBIC CONDITIONS

A substantial amount of sediment phosphorus can be bound in bacterial biomass. In this study the fractional composition of phosphorus in the bacteria Pseudomonas was determined by sequential extraction with ammonium chloride, sodium hydroxide and hydrochloric acid according to the scheme of Hieltjes & Lijklema (1980). Both non-labelled and P-32-labelled bacteria were used for fractionation. Up to 80% of the bacterial phosphorus was found in the NaOH-nRP fraction, which is in agreement with the results of Hupfer & Uhlman (1992) for Acinetobacter and activated sludge obtained with the sequential extraction scheme of Psenner et al. (1985). A significant correlation was found between bacterial biomass and the amount of phosphorus retained in the NaOH-nRP fraction when sediments were fractionated. Additional experiments with P-32-labelled Pseudomonas in sediment-water systems were performed in order to follow bacterial release of phosphorus under aerobic and anaerobic conditions. These studies did not sustain the hypothesis that anaerobic conditions lead to rapid release of phosphorus from bacterial cells.