TOXIC EFFECTS ON RESPIRATORY ACTIVITIES OF PHENOL-OXIDIZING CULTURES GROWN FROM VARIOUS CONDITIONS

This study examined the toxic effects on respiratory activities of thr ee cultures of phenol-oxidizing bacteria grown with two chemostats at mean cell retention times (MCRT) of 3.8 and 18.7 days, respectively, a nd one with rotating biological contactors (RBC) at MCRT of 71.0 days. Bacterial activity was evaluated by measuring specific oxygen uptake rates (SOUR) for the three cultures when subjected to various concentr ations of phenol (within 1000 mg 1(-1)), and two concentrations of tri chloroethylene (2, and 20 mg 1(-1)). Phenol exposure data were also mo deled using Haldane kinetics and then solved by nonlinear regression r outine. According to those results, cells from the chemostat with 3.8 MCRT have the highest respiratory activities, while those from RBC rea ctor are least active. When exposed to 2 mg 1(-1) of TCE, all of the c ultures exhibited no significant toxic effect. however, increasing the TCE dosage to 20 mg 1(-1) obviously inhibited the cell's respiratory activities, particularly for the cultures with a RBC reactor.