DEGRADATION ACTIVITY OF ADHERED AND SUSPENDED PSEUDOMONAS CELLS CULTURED ON 2,4,6-TRICHLOROPHENOL, MEASURED BY INDIRECT CONDUCTIMETRY

The degradation activity (expressed as specific CO2 production rates) of adhered and suspended Pseudomonas cells, strains SP1 and SP2, durin g the degradation of 2,4,6-trichlorophenol (2,4,6-TCP), was compared u sing indirect conductimetry technique. This technique is defined as th e measurement of CO2 ionization in an alkaline solution and expressed as the negative conductance change values of such solution. The attach ment surfaces were porous glass and silicone rubber. The 2,4,6-TCP con centrations ranged from 10 to 500 mg l(-1). Specific respiration rates were determined from CO2 evolution rates and biomass yields of both s uspended and adhered cell cultures. CO2 evolution rates were determine d after conversion of conductance change values into CO2 produced valu es. Results indicate that glass-adhered cells reached a higher maximum specific CO2 evolution rate (QCO(2max)) than both suspended and silic one rubber-adhered cells. However, suspended cells showed a lower satu ration constant (K-s) than the adhered cells. These results suggest th at depending on support nature the respiration activity of adhered cel ls could be higher than of suspended cells. Moreover, the indirect con ductimetry technique could efficiently be used by measurements of resp iration activities of both attached or suspended xenobiotic-degrading micro-organisms.