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This article in JEQ

  1. Vol. 30 No. 6, p. 1911-1918
     
    Received: Aug 17, 2000
    Published: Nov, 2001


    * Corresponding author(s): mkfstone@nature.berkeley.edu
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doi:10.2134/jeq2001.1911

Enhanced Phenanthrene Biodegradation in Soil by Slender Oat Root Exudates and Root Debris

  1. Ryan K. Miya and
  2. Mary K. Firestone *
  1. Department of Environmental Science, Policy, and Management, Ecosystem Sciences Div., 151 Hilgard Hall no. 3110, Univ. of California, Berkeley, CA 94720-3110

Abstract

To investigate the mechanisms by which slender oat (Avena barbata Pott ex Link) enhances phenanthrene biodegradation, we analyzed the impacts of root exudates and root debris on phenanthrene biodegradation and degrader community dynamics. Accelerated phenanthrene biodegradation rates occurred in soils amended with slender oat root exudates as well as combined root debris + root exudate as compared with unamended controls. Root exudates significantly enhanced phenanthrene biodegradation in rhizosphere soils, either by increasing contaminant bioavailability and/or increasing microbial population size and activity. A modified most probable number (MPN) method was used to determine quantitative shifts in heterotrophic and phenanthrene degrader communities. During the first 4 to 6 d of treatment, heterotrophic populations increased in all amended soils. Both root debris–amended and exudate-amended soil then maintained larger phenanthrene degrader populations than in control soils later in the experiment after much of the phenanthrene had been utilized. Thus, root amendments had a greater impact over time on phenanthrene degraders than heterotrophs resulting in selective maintenance of degrader populations in amended soils compared with controls.

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Copyright © 2001. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.30:1911–1918.