Microbial
Community Structures Correlated with Geochemistry: a DNA-based Exploration
Technology
Dimster-Denk, Dago1, Matthew
Ashby1, Emmanuel Mongodin2, Karen Nelson2,
Thomas Lorenson3 (1) Taxon Biosciences, Inc, Tiburon, CA (2) The
Institute for Genomic Research, Rockville, MD (3) U.S. Geological Survey, Menlo
Park, CA
The development of molecular technologies
in recent years allowing for the direct detection of microbial cells without
laboratory culturing is leading to a much greater understanding of the
incredible species richness in the microbial world, as well as their ubiquitous
distribution in the environment. Although the presence of microbes on the whole
may be ubiquitous, the distribution of individuals, or sub-groups, with varying
metabolic potential is not. Ultimately the local geochemistry determines which
organisms are able to survive in a given ecological niche through natural
selection. Therefore, a method to describe the structure of a microbial
community at a given locale would provide a very sensitive biological
“fingerprint” of the geochemistry of the site.
A proprietary DNA-based technology termed
SARD (for Serial Analysis of Ribosomal DNA) has been developed that allows for
high resolution, quantitative surveys of microbial communities. SARD surveys
have been performed on a variety of near surface and sub-surface samples
located both onshore and offshore. A database of more than 130,000 DNA
sequences was assembled from hydrocarbon-associated samples. Two-dimensional
hierarchal cluster analysis identified specific DNA sequences that are
correlated with various geochemical parameters that characterize the sites. A
series of quantitative assays have been developed for DNA sequences which
strongly correlate to specific geochemical features. This technology allows
determinations of geochemistry based on the distribution of microbial indicator
species.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California