The influence of experimental conditions on the assessment of the toxicity of 2,4-dichlorophenol to anaerobic degradative bacteria

The toxicity of 2,4-dichlorophenol (2,4-DCP) to anaerobic bacteria in refuse cultures was investigated at two temperatures (30 and 37 degrees C) and after two different exposure periods to the toxicants. It was shown that at 0.52mM 2,4-DCP the time of exposure of microorganisms to 2,4-DCP affected the relative activity (Av) of the production of methane. Av values at the beginning of the steady-state phase were lower than those recorded two weeks later. The incubation temperature selected also critically affected the assessment of anaerobic toxicity; at 37 degrees C an imbalance of the activities of fermentative bacteria and acetogens with those of methanogens was observed.