'Unculturable' bacterial diversity: An untapped resource

More than 99% of bacteria from environmental samples remain 'unculturable' in the laboratory. Many of these 'unculturable' bacteria represent new phylotypes, families and divisions in domain bacteria and archaea. 'Unculturable' bacterial diversity presents a vast gene pool for biotechnological exploitation and poses a major challenge for microbiologists to understand their phylogenetic relationship and ecological significance. New culture techniques along with culture-independent methods, like PCR amplification from microbial community DNA (metagenome) and functional or sequence-based screening of metagenomic DNA libraries are proving useful for exploitation of 'unculturable' bacteria. Environmental genome sequencing efforts are aiding better understanding of the community structure and their physiological importance in the ecosystem.