Metagenomic libraries from uncultured microorganisms
Most microorganisms in the environment are refractory to culturing by standard methods. In many habitats, as few as 0.1-1% of the viable cells are culturable, and community diversity estimated by molecular methods that bypass culturing far exceeds that which can be accounted for by culturing. Analyses of environments as diverse as soil, hot springs, oceans, mammalian cavities and insect tissue have revealed uncultured species richness (1-6). Many thousands of bacterial species remain to be discovered and studied.