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Title: MICROBIAL COMMUNITY STRUCTURE AND THE RHIZOSPHERE EFFECT

Author
item Buyer, Jeffrey
item Blackwood, Christopher
item Roberts, Daniel
item PAUL, ELDOR - COLORADO STATE UNIV

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/2002
Publication Date: 11/11/2002
Citation: BUYER, J.S., BLACKWOOD, C.B., ROBERTS, D.P., PAUL, E.A. MICROBIAL COMMUNITY STRUCTURE AND THE RHIZOSPHERE EFFECT. AGRONOMY ABSTRACTS. 2002. S03-buyer 123344-Poster.

Interpretive Summary: .

Technical Abstract: We hypothesized that the effect of plant roots on microbial community structure would be strongest for copiotrophic or 'r' selected bacteria, while there would be little or no effect on oligotrophic or 'K' selected microorganisms. Communities were characterized by soil fatty acid analysis and by substrate utilization assays for bacteria and fungi. Fatty acid analysis revealed a very strong soil effect but little plant effect on the microbial community, indicating that the overall microbial community structure was not greatly affected by the rhizosphere. There was a strong rhizosphere effect detected by the substrate utilization assay for fast growing aerobic heterotrophic bacterial community structure. There was a much weaker rhizosphere effect on fungal communities than bacterial communities as measured by the substrate utilization assays. At this coarse level of community analysis the rhizosphere microbial community was impacted most by soil effects, and the rhizosphere only affected a small portion of the total bacteria. This suggested that a rhizosphere community may be assembled in part through random encounters between roots and dormant 'r' selected bacteria. This was consistent with the results of a preliminary field experiment using T-RFLP of community ribosomal DNA which indicated that the rhizosphere community was less stable than the bulk soil community.