Characterization of Epiphyte Community Structure and Biomass through Analysis of Phospholipid Fatty Acids and Extractable Lipid Phosphate
McDade, Gerald T.
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The Upjohn Pond in Portage, Michigan is a natural bioremediation site where diverse microbial communities have shown the ability to remove a suite of organic contaminants. Though the function of these microbial communities has been well studied, little is known about structure or biomass of the communities. Changes in community structure and biomass were believed to coincide with an existing organic contaminant gradient within the pond. Phospholipid fatty acid (PLFA) profile analysis, a rapid and inexpensive technique which does not rely on selective culturing, was used to analyze community structure. Lipid phosphate quantifictation, a less labor intensive and more accurate measure of biomass than traditional counting methods, was used to estimate biomass. Fatty acid profiles indicated a change in the composition of microbial communities along the contaminant gradient. Communities closest to the pond's contaminant source had fatty acid profiles which were indicative of Gram positive bacteria, while communities furthest removed from the contamination source most resembled Gram negative bacteria. Similar results were obtained from the biomass analysis. Microbial biomass also correlated loosely with the contamination gradient in the pond. In general, biomass was higher closer to the contaminant source. However, community structure and biomass were likely influenced by several other factors as well.