Metagenomic analysis of uncultured Cytophaga and glycanses in marine consortia

Most bacteria and archaea in natural environments still cannot be isolated and cultivated as pure cultures in the laboratory, and the microbes that can be cultured appear to be quite different from uncultured ones. Consequently, the phylogenetic composition, physiological capacity and genetic properties of natural microbes have to be deduced from bulk properties of microbial assemblages, fluorescence in situ hybridization (FISH) assays, and from a variety of PCR-based methods applied to DNA isolated directly from natural samples. Another culture-independent approach is to clone microbial DNA directly into appropriate vectors and to screen the resulting metagenomic library, which theoretically consists of all possible genes from the microbial assemblage. We have been using this approach to examine microbial communities in the Delaware Estuary and coastal waters and the western Arctic Ocean.