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United States Department of Agriculture

Agricultural Research Service

Title: Fatty Acid Methyl Ester (Fame) Profiles As a Tool to Investigate Community Structure of Two Agricultural Soils

Authors
item Ibekwe, Abasiofiok
item Kennedy, Ann

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 1998
Publication Date: N/A

Interpretive Summary: As part of our continuing effort in understanding the effects of microbial composition at the rhizosphere of most crops and the effects of growth environment, a field and a greenhouse experiments were conducted to examine whether there are differences in microbial composition between field and the greenhouse environments. Understanding microbial composition between the field and the greenhouse is critical because a lot of experimental work conducted in the greenhouse are extrapolated to what might happen under field conditions. This is especially significant when new organisms are introduced to the environment. The use of lipid analysis of its phospholipid content is one of two methods of analyzing microbial community composition. This method is quick and represent total living cell mass in the soil. We have used this method to show differences in microbial composition between field soil and greenhouse soils. This is the first time where phospholipid fatty acid compositions from field are compared to that of the greenhouse. This information will be useful in determining how results from greenhouse studies can be applied to field condition.

Technical Abstract: The accurate description of soil microbial community structure by phospholipid fatty acid (PLFA) profiles is based on the strong relationship between the phylogeny of microorganisms and their PLFA profiles. Based on the strength of this relationship, a comparative study was conducted using potential C source utilization patterns in microtiter plates to see if results of changes in microbial community structure from the two methods are similar. Field and greenhouse experiments were conducted using Palouse and Ritzville silt loams soils. Soil samples from wheat, barley, pea, jointed goatgrass and downy brome. Rhizospheres as well as nonrhizosphere soils were used for these analyses. Principal component analysis (PCA) of PLFA profiles and C source utilization patterns were used to describe changes in microbial community structure from the two soils under different environments. In general biomass was higher in all the field samples than greenhouse samples. PCA of the two soils from the rhizosphere of different plants in the field and greenhouse study showed a clear separation and a clustering of all the field samples in one cluster and the greenhouse samples in another. When microbial communities from the same soils were cultured and their PLFA profiles analyzed, there was no separation of the communities, suggesting that culturable microorganisms from these soils may be from few identical species that can grow on the medium used. Analysis of C utilization patterns revealed the same clustering of different communities as found when PLFA profiles from soil communities were used for analysis. Results indicate that PLFA profiles in an effective method for community analysis, and may also be useful in community description.

Last Modified: 10/25/2014