Development of new primer systems for the detection of the polyphosphate kinase gene in activated sludge

An enzyme which regulates the metabolism of phosphate is the polyphosphate kinase (ppk). Therefore, it is an important criterion for the identification of polyphosphate accumulating bacteria (PAO) in activated sludge. With the published primer systems it is currently impossible to detect the ppk gene simultaneously from different microorganisms. The aim of this study was the development of new primer systems for the acquisition of a wide range of ppk sequences. The specific amplification was tested by cloning and sequencing. As an outcome a large diversity of ppk sequences was detected. In addition differences in the composition of the ppk sequences in samples of the activated sludge of the investigated plants were shown by using the terminal restriction fragment length polymorphism analysis (T-RFLP).