BACTERIAL SCISSION OF ETHER BONDS

Ether bonds are found in a wide variety of natural and industrially ma nufactured xenobiotic compounds and have been associated with the leve l of recalcitrance of certain environmental pollutants. The main sourc es of such pollutants released into the environment are formulations o f pesticides and detergents. Environmental persistence of a number of these compounds has been implicated as the cause of severe toxicologic al problems. A selection of representative pollutants are described to illustrate the diversity of their molecular structure, and their micr obiological biodegradation and potential toxicity are discussed. A num ber of mired bacterial cultures and individual strains have evolved th e capacity to utilize many of these omnipresent ether-containing compo unds as carbon and energy sources; biodegradation is often via the age ncy of an ether-cleavage mechanism. Biodegradation-competent bacteria exhibit a suprising variety of ether scission. mechanisms. These inclu de those based on oxygenases, cytochrome P-450, hydroxyl shift hydroly sis, anaerobic O demethylation, oxidative mechanisms reductive mechani sms and carbon-oxygen lyases. A unifying feature involving the generat ion of hemiacetals and beta-elimination is proposed for many of the et her cleavage mechanisms displayed by bacteria.