Fatty acid methyl ester (FAME) profiles as a tool to investigate community structure of two agricultural soils |
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Authors: | Ibekwe AM Kennedy AC |
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Institution: | (1) USDA-ARS, Washington State University, Pullman, WA 99164-6421, USA |
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Abstract: | Soil microbiological parameters may be the earliest predictors of soil quality changes. Recently, molecular techniques such
as fatty acid methyl ester (FAME) profiles have been used to characterize soil microbial communities. Fatty acid methyl ester
(FAME) from whole soil may be derived from live cells, dead cells, humic materials, as well as plant and root exudates. Our
objective was to verify differences in FAME profiles from two agricultural soils with different plants. Soil samples were
collected from Ritzville and Palouse silt loams for fatty acid analysis. Soil samples from wheat (Triticum aestivum L.), barley
(Hordeum vulgare L.), pea (Pisum sativum L.), jointed goatgrass ( Aegilops cylindrica L.) and downy brome (Bromus tectorum
L.) rhizospheres were also collected for fatty acid analysis. Principal component analysis (PCA) of the two soils explained
42% of the variance on PC1, which accounted for Palouse soil. Ritzville soil accounted for 19% of the variance on PC2. Factor
analysis showed that rhizosphere microbial communities from various plant species may differ depending on the plant species.
Presence of Gram-positive bacteria as identified by a15:0, i15:0, a17:0 and i17:0 peaks were similar between rhizosphere and
nonrhizosphere soils. Gram-negative bacteria characterized by short chain hydroxy acids (10:03OH and 12:03OH) as well as cyclopropane
acids (cy17:0) were higher in rhizosphere soil than nonrhizosphere. This indicates a possible shift in the bacterial community
to more Gram-negative bacteria and fewer Gram-positive bacteria in the rhizospheres of the plants species studied. |
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Keywords: | community structure fatty acid methyl esters rhizosphere soil quality |
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