Picochloropsis malayensis gen. et sp. nov. (Chlorellales, Chlorophyta), an ammonium tolerant, polyphosphate‐accumulating microalga from seawater

SUMMARYThe significant concentrations of phosphate in wastewater can be considered as an important fertilizer source. Some microalgae uptake phosphate from wastewater and store it in the form of polyphosphate (polyP). Therefore, biological phosphorus recovery processes have been attracting significant attention recently. However, wastewaters are often rich in ammonium, and so microalgae used for phosphorus recovery should be tolerant of this component. In the present study, 151 microalgae were isolated from freshwater, brackish water and seawater. Among them, 11 strains showed higher growth rates in ammonium‐rich media. Of these, the strain SLG4‐06 originating from a marine environment showed the highest polyP accumulation rate and was selected as the most potential alga for phosphorus recovery from wastewater. Based on the morphological and ultrastructural characteristics and phylogenetic analyses of nuclear‐encoded 18S rDNA and chloroplast‐encoded rbcL of strain SLG4‐06, we propose Picochloropsis malayensis gen. et sp. nov. for this strain in the Chlorellales, Trebouxiophyceae. Because P. malayensis can grow in both seawater and freshwater environments, it may be suitable for wastewater treatment in marine aquaculture ponds with widely fluctuating salinity levels.