PHOSPHORUS RELEASE BY PURE CULTURES OF ACINETOBACTER SP - EFFECT OF THE GROWTH STAGE WITH CELLS CULTIVATED ON VARIOUS CARBON-SOURCES

In order to understand biological phosphorus removal mechanisms, the r ole of growth stage and volatile fatty acids (VFA) on phosphate releas e in the anaerobic stage of P removal by three Acinetobacter strains w as investigated. The phosphate release in anaerobic conditions was aff ected by the physiological state of cells and by the carbon source use d. When the experiments were made with stationary growth phase cells, the release of phosphate was higher for all three strains cultured on acetic, propionic and butyric acid. Cells showed a limit to the amount of phosphate that could be released from total phosphate accumulated. Only 5-38% of P accumulated by the log cells and 18-58% of total P ac cumulated by stationary cells could by released. The ratio between the amount of P released and organic substrate removed under anaerobic co ndition varies depending on VFA types and tested strains.