Culture-independent studies have shown that microbial consortia in natural environments are incredibly diverse and are dominated by bacteria and archaea substantially different from microbes maintained in pure laboratory cultures. Recent studies indicate, however, that previous culture-independent studies using PCR-based methods have largely overlook an important group of uncultured bacteria, the Cytophagales. These bacteria appear to be abundant in the oceans and probably other oxic environments. Although well known to be active in degradation of structural glycans such as cellulose and chitin, no cellulase or chitinase gene has been sequenced from a Cytophaga, except those recently found by whole genome sequencing of Cytophaga hutchinsonii by the DOE Joint Genome Institute (JGI). We hypothesize that the key to understanding consortia and their function in organic matter mineralization in oxic environments is to focus on uncultured Cytophagales, genes encoding endoglycanases, and other functional genes. The metagenomic approach used by this project consisted of constructing large insert libraries with DNA directly (no PCR) from uncultured microbial consortia found in the Arctic Ocean and Delaware Estuary. Our results provide insights into new types of bacterial metabolisms which have not considered adequately before, but which may change our views of the global carbon cycle.
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