Degradation of mixtures of monochlorophenols and phenol as substrates for free and immobilized cells of Alcaligenes sp. A7-2

Abstract

The biodegradation of the three isomeric monochlorophenols 2-(2CP), 3- (3CP) and 4-chlorophenol (4CP) and phenol by the constructed strain Alcaligenes sp. A7-2 was investigated. Mineralization took place in the order: phenol >4CP >2CP >3CP, whereas 3CP was mineralized only co-metabolically. In substrate mixtures with phenol, degradation of 4CP was decelerated but degradation of 2CP was accelerated. Free cells in batch culture showed biphasic growth with an equimolar mixture of 2CP and 4CP as substrates, perhaps due to diauxie. Degradation patterns obtained with free cells in batch culture were confirmed with immobilized cells in continuous culture. Immobilized cells of Alcaligenes sp. A7-2 built up a biofilm on the lava that was used as filling material in the packed-bed reactors. The continuous cultures remained stable despite increasing input rates of chlorophenol and phenol mixtures up to 1.16 mMo1.1−1.h−1 for several weeks.