Effects of Six Different Functional Groups and Their Position on the Bacterial Metabolism of Monosubstituted Phenols under Anaerobic Conditions

The biodegradability of phenol and all isomers of aminophenol (AP), chlorophenol (CP), hydroxybenzoate (HB), dihydroxybenzene (DHB), methylphenol (MP), and nitrophenol (NP) were examined under denitrifying and methanogenic conditions. All isomers of CP and NP inhibited denitrification, while each NP isomer was reduced to AP under methanogenic conditions. All CPs were stoichiometrically mineralized to CH 4 . All AP isomers were mineralized under denitrifying conditions, while only the 4-AP isomer was biodegraded under methanogenic conditions. Under denitrifying conditions, the 1,3-DHB and 1,4-DHB isomers were mineralized, while the 1,2-DHB was persistent. 1,2-DHB was reductively dehydroxylated to phenol under methanogenic conditions. All MPs were mineralized under both anaerobic conditions. 2-MP incubated under methanogenic conditions and the 4-MP incubated under denitrifying conditions underwent methyl group oxidation to 2-hydroxybenzyl alcohol and 4-hydroxybenzoate, respectively. All HB isomers incubated under both anaerobic conditions produced stoichiometric quantities of N 2 and CH 4 . These results suggest that the anaerobic condition and the nature of the substituent can influence the metabolism and toxicity of phenolic compounds.