Biotransformation of halogenated nonylphenols with sphingobium xenophagum bayram and a nonylphenol-degrading soil-enrichment culture.

When discharged in chlorinated wastewater, alkylphenol ethoxylate metabolites (APEMs) are often discharged in halogenated form (XAPEMs, X = Cl, or Br). The potential environmental impact of XAPEM release was assessed by studying the biotransformation of halogenated nonylphenol by Sphingobium xenophagum Bayram and a soil-enrichment culture. S. xenophagum Bayram transformed chlorinated nonylphenol (ClNP) slowly and nearly completely to form nonyl alcohol; the monobrominated nonylphenol (BrNP) and dibrominated nonylphenol were transformed cometabolically with nonylphenol (NP) as the primary substrate. The presence of either ClNP or BrNP in the S. xenophagum Bayram cultures retarded the transformation of nonhalogenated NP. NP-degrading soil cultures transformed nonhalogenated NP to a mixture of nonyl alcohols but were not capable of transforming either ClNP or BrNP. The presence of either ClNP or BrNP retarded the transformation of nonhalogenated NP in the soil cultures, as was observed in S. xenophagum Bayram cultures. Predicting the environmental fate of alkylphenol ethoxylate residues requires considering APEM halogenation during effluent chlorination and inhibitory effects as well as the refractory nature of halogenated metabolites.