Anaerobic degradation of fluorinated aromatic compounds

Anaerobic enrichment cultures with sediment from an intertidal strait as in oculum were established under denitrifying, sulfate-reducing, iron-reducing and methanogenic conditions to examine the biodegradation of mono-fluoroph enol and mono-fluorobenzoate isomers. Both phenol and benzoate were utilize d within 2-6 weeks under all electron-accepting conditions. However, no deg radation of the fluorophenols was observed within 1 year under any of the a naerobic conditions tested. Under denitrifying conditions, 2-fluorobenzoate and 4-fluorobenzoate were depleted within 84 days and 28 days, respectivel y. No loss of 3-fluorobenzoate was observed. All three fluorobenzoate isome rs were recalcitrant under sulfate-reducing, iron-reducing, and methanogeni c conditions. The degradation of the fluorobenzoate isomers under denitrify ing conditions was examined in more detail using soils and sediments from d ifferent geographic regions around the world. Stable enrichment cultures we re obtained on 2-fluorobenzoate or 4-fluorobenzoate with inoculum from most sites. Fluoride was released stoichiometrically, and nitrate reduction cor responded to the values predicted for oxidation of fluorobenzoate to CO2 co upled to denitrification. The 2-fluorobenzoate-utilizing and 4-fluorobenzoa te-utilizing cultures were specific for fluorobenzoates and did not utilize other halogenated (chloro-, bromo-, iodo-) benzoic acids. Two denitrifying strains were isolated that utilized 2-fluorobenzoate and 4-fluorobenzoate as growth substrates. Preliminary characterization indicated that the strai ns were closely related to Pseudomonas stutzeri.