performed the enrichment process using mixed cultures under aerobic feast/famine conditions which were characterized using RT-PCR (Reverse transcription-polymerase chain reaction). According to their results, the consortium consisted of bacteria belonging to Azoarcus, Amaricoccus and Thauera species.Furthermore, Bengts son and co-workers [14] as well as Pisco and co-workers [15] studied the enrichment of mixed cultures under alternating anaerobic/aerobic conditions. Using the technique of fluorescent in situ hybridization (FISH) they identified the pre-dominant strains which were Defluviicoccus vanus and Candidatus Competibacter phosphatis. However, none of those reports investigated the PHAs production efficiency of the isolates that had been identified as the predominant strains of the mixed consortium, so,there is no comparison between the results obtained using the enriched culture and the isolated strains.