Acclimatization of mixed cultures was carried out in Erlenmeyer flask containing enriched micro-organisms that was operated in batch mode with the addition of phenol up to concentration level of 1000mgl 1. The competency of the uncharacterized microbial consortia was evaluated in continuous cultures supplemented with phenol as carbon source. Fig. 2 shows the acclimatization stage that resulted in nearly complete reduction of phenol in 1752 h.