Dipping into the Rare Biosphere

Abstract

When molecular methods were introduced into microbial ecology in the mid-1980s (1), there were two surprises: Most DNA sequences found bore no resemblance to organisms known from cell culture, and the microorganisms that could be cultured were almost never found in molecular surveys (see the figure). These findings indicated that microbial diversity is much larger than had been anticipated. It also revealed that some bacteria occur at such low abundance that molecular techniques cannot detect them. In the meantime, marine microbiology has become an extremely active and innovative field. For example, two reports in this issue, by Markert et al. on page 247 (2) and Not et al. on page 253 (3), demonstrate that current molecular techniques can suggest geographic distribution and characterize the symbiotic relationships that enable organisms to survive in extreme habitats. Morever, recent advances in sequencing technology are beginning to open our eyes to the huge dimensions of the microbial diversity hidden in nature