A novel PA Medium (PAM) for efficient screening of phosphate-accumulating organisms (PAOs) was developed taking Serratia marcescens NBRI1213 as model organism. The defined National Botanical Research Institute's growth medium (NBRI) supplemented with 0.1% maltose, designed for quantitative estimation of phosphate accumulation was designated as PAM. Our work suggested usage of PAM for efficient qualitative screening and as a microbiological medium for preferential selection of PAOs on Petri-plates. For qualitative screening of PAOs. Toluidine blue-O dye (TBO) was supplemented in PAM, designated as PAM-TBO. Qualitative analysis of phosphate accumulated by various groups correlated well with grouping based upon quantitative analysis of PAOs, effect of carbon, nitrogen, salts, and phosphate accumulation-defective transposon mutants. For significantly increasing sample throughput, efficiency of screening PAOs was further enhanced by adaptation of PAM-TBO assay to microtiter plate based method. It is envisaged that usage of this medium will be salutary for quick screening of PAOs from environment. (C) 2011 Elsevier Ltd. All rights reserved.