Polyphosphate-degrading enzymes in Acinetobacter spp. and activated sludge

Area of Science:

• Microbiology
• Environmental Science
• Biochemistry

Background:

• Polyphosphate accumulation is crucial for biological phosphorus removal in wastewater treatment.
• Acinetobacter species are key players in these microbial communities.
• Understanding the enzymes involved is vital for optimizing wastewater treatment processes.

Purpose of the Study:

• To characterize polyphosphate-degrading enzymes in Acinetobacter species and activated sludge.
• To investigate the relationship between enzyme activity, growth rates, and phosphorus accumulation.
• To correlate enzyme activities with biological phosphate removal efficiency.

Main Methods:

• Enzyme assays were performed on Acinetobacter strains and activated sludge samples.
• Polyphosphate: AMP phosphotransferase and polyphosphatase activities were measured.
• Kinetic parameters (Km, Vmax) and optimal conditions (pH, temperature) were determined.
• Correlations between enzyme activities, growth rates, and phosphorus content were analyzed.

Main Results:

• Polyphosphate: AMP phosphotransferase activity in Acinetobacter decreased with higher growth rates.
• Optimal conditions for this enzyme were pH 8.5 and 40°C, stimulated by ammonium sulfate.
• Polyphosphatase activity was detected and strongly stimulated by high salt concentrations (NH4Cl).
• A positive correlation existed between polyphosphate:AMP phosphotransferase, adenylate kinase activity, and phosphorus accumulation in Acinetobacter.
• Adenylate kinase activity in activated sludge correlated with biological phosphate removal capacity.

Conclusions:

• Enzyme activities involved in polyphosphate metabolism vary with growth conditions in Acinetobacter.
• Adenylate kinase activity serves as a reliable indicator for biological phosphate removal in activated sludge.
• These findings contribute to understanding microbial phosphorus cycling in wastewater treatment.