title: Nitrogen limitation and nitrogen fixation during alkane biodegradation in a sandy soil.
abstract: We investigated nutrient limitations during hydrocarbon degradation in a sandy soil and found that fixed nitrogen was initially a limiting nutrient but that N limitation could sometimes be overcome by N2 fixation. Hydrocarbon biodegradation was examined in an unsaturated sandy soil incubated aerobically at 20 degrees C with propane or butane and various added nutrients. Propane and butane degradation proceeded similarly during the first 3 months of incubation. That is, bacteria in soil amended with N oxidized these hydrocarbons more rapidly than in controls without nutrient additions or in soil with added phosphate or trace minerals. Both propane- and butane-amended soil apparently became N limited after the initial available inorganic N was utilized, as indicated by a decrease in the rates of hydrocarbon degradation. After 3 months, propane and butane degradation proceeded differently. Bacteria in propane-degrading soil apparently remained N limited because propane degradation rates stayed low unless more N was added. In contrast, bacteria in butane-degrading soil appeared to overcome their N limitation because butane degradation rates later increased regardless of whether more N was added. Analyses of total N and acetylene reduction assays supported this apparent surplus of N in butane-amended soil. Total N was significantly (P < 0.01) higher in soil incubated with butane and no N amendments than in soil incubated with propane, even when the latter was amended with N. Acetylene reduction occurred only in butane-amended soil. These results indicate that N2 fixation occurred in butane-amended soil but not in propane-amended soil.
authors.affiliation: Department of Environmental Science and Engineering, Oregon Graduate Institute of Science & Technology, Portland 97291-1000.
authors.forename: P L
authors.initials: PL
authors.lastname: Toccalino
authors.forename: R L
authors.initials: RL
authors.lastname: Johnson
authors.forename: D R
authors.initials: DR
authors.lastname: Boone
mesh_terms: D000114:Acetylene / Q000378:metabolism; D000473:Alkanes / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism; D001673:Biodegradation, Environmental; D002073:Butanes / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009586:Nitrogen Fixation; D010084:Oxidation-Reduction; D011407:Propane / Q000378:metabolism; D012988:Soil Microbiology
chemical_list: D000473:Alkanes; D002073:Butanes; C046888:butane; D009584:Nitrogen; D000114:Acetylene; D011407:Propane