PHOSPHATE-UPTAKE KINETICS BY ACINETOBACTER ISOLATES

Acinetobacter isolates from activated sludge treatment plants of fores t industry were used as model organisms for polyphosphate accumulating bacteria to study excess phosphate uptake by the overplus phenomenon as well as luxury uptake of phosphate during growth. The initial, rapi d phosphate uptake by the phosphorus-starved Acinetobacter isolates (t he overplus phenomenon) followed the Michaelis-Menten model (maximum i nitial phosphate uptake rate 29 mg P g(-1) dry mass (DM) h(-1), half-s aturation constant for excess phosphate uptake 17 mg P L(-1)). During the rapid uptake no growth was observed, but most cells contained poly phosphate granules. Also growth and luxury uptake of phosphate could b e modeled with the Michaelis-Menten equation (maximum phosphate uptake rate 3.7-12 mg P g(-1) DWI h(-1), half-saturation constant for growth 0.4-6.0 mg P L(-1), maximum specific growth rate 0.15-0.55 h(-1)). (C ) 1997 John Wiley & Sons, Inc.