Influence of exposure time on phenol toxicity to refinery wastewater bacteria

摘要

Influence of exposure time on the response of pure cultures of bacteria and microbial community of petroleum refinery wastewater to toxicity of phenol was assessed through TTC-dehydrogenase activity (DHA) inhibition test.At sufficient concentrations, exposure of these bacterial cells to phenol resulted in inhibition of dehydrogenase activity. InPseudomonassp. RWW2 andEscherichiasp. DISK2, phenol progressively inhibited dehydrogenase activity at 200 - 1400 mg/l at all the exposure time. However, inBacillussp. DISK1,Pseudomonassp. DAF1 and microbial community, increase in exposure time resulted in stimulation of dehydrogenase activity at lower concentrations of phenol. The toxicity threshold concentrations of phenol vary among the bacterial strains and the exposure time and indicate that bacteria could acclimate to phenol with increase in exposure time. At concentrations higher than 800 mg/l, phenol toxicity was not overcome inPseudomonasandEscherichiaspecies as well as the microbial community.It is suggested that for acute TTC-dehydrogenase assay involving bacteria, reliable and reproducible result would be best achieved within 48 h.