Degradation of hydrohalocarbons and brominated compounds by methane- and propane-oxidizing bacteria

Concern over the use of chemicals that potentially contribute to ozone depl etion and the greenhouse effect has led to a ban on chlorofluorocarbons (CF Cs) and potential limitations on the use of methyl bromide and other bromin ated fumigants. The objective of this work was to test naturally occurring aerobic microorganisms for the ability to degrade brominated fumigants and the hydrohalocarbons that have been developed to replace CFCs. The bacteria l strains used in this study degraded a significant percentage of the hydro halocarbons and brominated fumigants tested, which were present at high sub strate levels. Degradation was often rapid and complete, ion chromatography results indicated the stoichiometric release of halogens for several of th e compounds tested. Many of the compounds were readily biodegradable at hig h concentrations and were metabolized by all of the strains tested, while o thers were more recalcitrant. The presence of these microorganisms in the e nvironment may represent a natural sink for some of these compounds; howeve r, the high substrate and bacterial concentrations used in this study were chosen for bioreactor development. Information about the biodegradability o f these compounds may make it easier to choose the most ecologically safe C FC replacements and fumigants.