An isolated bacterium, Alcaligenes denitrificans ITRC-4, metabolizes 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) under both aerobic and anaerobic conditions. The aerobic metabolism is inhibited by 38% and 47% in the presence of 1.0 g L-1 of sodium acetate and sodium succinate, respectively, but remains uninhibited in the presence of 1.0 g L-1 of glucose. Also, the metabolism is inhibited completely in the presence of biphenyl vapors, as well as 0.8 g L-1 of 2,2'-bipyridyl. Under anaerobic conditions, DDT is metabolized into 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), which is further enhanced by 50% in the presence of 1.0 g L-1 of glucose. Besides, the bacterium also metabolizes 4-chlorobenzoate, which is accompanied by the release of chloride ions.