ARS | Publication request: CHARACTERIZATION OF DEPTH- AND REDOX-RELATED MICROBIAL COMMUNITY STRUCTURE IN A RIVER FLOODPLAN CONTINUM USING 16S RNA-BASED APPROACHES AND FATTY ACID METHYL ESTER (FAME) ANALYSIS

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: January 11, 2006
Publication Date: May 21, 2006
Citation: Song, Y., Deng, S., Acosta Martinez, V. 2006. Characterization of depth- and redox-related microbial community structure in a river floodplan continum using 16s rna-based approaches and fatty acid methyl ester (fame) analysis[abstract]. American Society for Microbiology.

Technical Abstract: Substrate availability and redox states in an ecosystem play crucial roles in regulating microbial abundance and community structure. We evaluated changes of microbial community under three redox conditions in a river floodplain continuum that was subject to seasonal flooding and metal contamination. Soils were collected from four sites at each of two locations along Tisza River in Hungary. Each soil profile was divided into three redox horizons: oxic, intermittent, and anoxic. Microbial communities were evaluated using 16S rRNA-based terminal-restriction fragment length polymorphism (T-RFLP) and fatty acid methyl ester (FAME) analysis. Abundance of Gram-positive bacteria increased with increasing soil depth and shifting from oxic to anoxic conditions. Gram-negative bacteria, fungi and actinomyces were more abundant in the oxic layers than in the intermittent and anoxic layers. Protozoa were detected only in the oxic layer. Despite wide variation in vegetation between sampling sites, bacterial communities in the oxic layers shared >50% similarity among sites. Considerable variation was shown among bacterial communities in the intermittent or anoxic layers. Bacterial richness (total numbers of T-RFLP bands) decreased with increasing soil depth. Bacterial communities were distributed more evenly in the oxic layers than the anoxic layers. The loss of diversity with increasing soil depth was due primarily to variation in redox states. Under oxygen limiting conditions, bacterial community structure was regulated by other stress factors such as organic carbon and water content.