title: Adaptation to and biodegradation of xenobiotic compounds by microbial communities from a pristine aquifer.
abstract: The ability of subsurface microbial communities to adapt to the biodegradation of xenobiotic compounds was examined in aquifer solids samples from a pristine aquifer. An increase in the rates of mineralization of radiolabeled substrates with exposure was used as an indication of adaptation. For some compounds, such as chlorobenzene and 1,2,4-trichlorobenzene, slight mineralization was observed but no adaptation was apparent during incubations of over 8 months. Other compounds demonstrated three patterns of response. For m-cresol, m-aminophenol, and aniline intermediate rates of biodegradation and a linear increase in the percent mineralized with time were observed. Phenol, p-chlorophenol, and ethylene dibromide were rapidly metabolized initially, with a nonlinear increase in the percent mineralized with time, indicating that the community was already adapted to the biodegradation of these compounds. Only p-nitrophenol demonstrated a typical adaptation response. In different samples of soil from the same layer in the aquifer, the adaptation period to p-nitrophenol varied from a few days to as long as 6 weeks. In most cases the concentration of xenobiotic added, over the range from a few nanograms to micrograms per gram, made no difference in the response. Most-probable-number counts demonstrated that adaptation is accompanied by an increase in specific degrader numbers. This study has shown that diverse patterns of response occur in the subsurface microbial community.
authors.affiliation: Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill 27514.
authors.forename: C M
authors.initials: CM
authors.lastname: Aelion
authors.forename: C M
authors.initials: CM
authors.lastname: Swindoll
authors.forename: F K
authors.initials: FK
authors.lastname: Pfaender
mesh_terms: D000627:Aminophenols / Q000378:metabolism; D000814:Aniline Compounds / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002722:Chlorobenzenes / Q000378:metabolism; D002733:Chlorophenols / Q000378:metabolism; D003408:Cresols / Q000378:metabolism; D015946:Ethylene Dibromide / Q000378:metabolism; D006846:Hydrocarbons, Halogenated / Q000378:metabolism*; D009596:Nitrophenols / Q000378:metabolism; D010636:Phenols / Q000378:metabolism*; D012988:Soil Microbiology; D014871:Water Microbiology
chemical_list: D000627:Aminophenols; D000814:Aniline Compounds; D002722:Chlorobenzenes; D002733:Chlorophenols; D003408:Cresols; D006846:Hydrocarbons, Halogenated; D009596:Nitrophenols; D010636:Phenols; C009947:1,2,4-trichlorobenzene; D015946:Ethylene Dibromide; C029107:4-chlorophenol; C023650:aniline; C024836:4-nitrophenol