A method for screening polyphosphate-accumulating mutants which remove phosphate efficiently from synthetic wastewater.

The biological process for phosphorus removal from wastewater is based on the use of bacteria capable of accumulating inorganic polyphosphate (polyp). We previously showed that a phoU mutation leads to polyp accumulation in Escherichia coli. The phoU mutant could be easily screened on agar plates containing 5-bromo-4-chloro-3-indolyl-phosphate (X-P(i)) after N-methyl-N'-vitro-N-nitrosoguanidine (NTG) mutagenesis. Here, we demonstrate that this method is also useful for screening polyp-accumulating mutants of bacterial strains isolated from soil and activated sludge samples.