title: Petroleum-degrading microbial numbers in rhizosphere and non-rhizosphere crude oil-contaminated soil.
abstract: Phytoremediation can be a cost-effective and environmentally acceptable method to clean up crude oil-contaminated soils in situ. Our research objective was to determine the effects of nitrogen (N) additions and plant growth on the number of total hydrocarbon (TH)-, alkane-, and polycyclic aromatic hydrocarbon (PAH)-degrading microorganisms in weathered crude oil-contaminated soil. A warm-season grass, sudangrass (Sorghum sudanense (Piper) Stapf), was grown for 7 wk in soil with a total petroleum hydrocarbon (TPH) level of 16.6 g TPH/kg soil. Nitrogen was added based upon TPH-C:added total N (TPH-C:TN) ratios ranging from 44:1 to 11:1. Unvegetated and unamended controls were also evaluated. The TH-, alkane-, and PAH-degrading microbial numbers per gram of dry soil were enumerated from rhizosphere and non-rhizosphere soil for vegetated pots and non-rhizosphere soil populations were enumerated from non-vegetated pots. Total petroleum-degrading microbial numbers were also calculated for each pot. The TH-, alkane-, and PAH-degrading microbial numbers per gram of dry soil in the sudangrass rhizosphere were 3.4, 2.6, and 4.8 times larger, respectively, than those in non-rhizosphere soil across all N rates. The presence of sudangrass resulted in significantly more TH-degrading microorganisms per pot when grown in soil with a TPH-C:TN ratio of 11:1 as compared to the control. Increased plant root growth in a crude oil-contaminated soil and a concomitant increase in petroleum-degrading microbial numbers in the rhizosphere have the potential to enhance phytoremediation.
authors: Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors: W D
authors: WD
authors: Kirkpatrick
authors: P M
authors: PM
authors: White
authors: D C
authors: DC
authors: Wolf
authors: G J
authors: GJ
authors: Thoma
authors: C M
authors: CM
authors: Reynolds
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D009584:Nitrogen / Q000378:metabolism; D010578:Petroleum / Q000032:analysis* / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology; D006109:Poaceae / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D012989:Soil Pollutants / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D010578:Petroleum; D012989:Soil Pollutants; D009584:Nitrogen