Pioneering work from the laboratories of Norman Pace and
others in the 1980s then began to examine microbial diversity
in natural populations by amplifying 16S ribosomal
RNA genes directly from environmental samples using the
polymerase chain reaction (PCR) [6]. The sequences of
these genes were compared to those of known taxa to infer
phylogenetic relationships. A truly marvelous diversity of
previously unknown prokaryotes, both Bacteria and
Archaea, has been revealed by this approach in the last
decade [7]. The range of environments being surveyed
grows daily, from insect and animal guts to a wide range of
soils and sediments, to more exotic locations such as
boiling hot springs, superheated ocean vents, subterranean
mine shafts, and Antarctic ice caps [4–7]. But to find
‘novel’ microbes, we need look no further than our own
bodies, as was shown early on by application of the ribosomal
RNA amplification method to identify the infectious
agent in bacillary angiomatosis, a rare disease caused by a
bacterial pathogen that had resisted isolation [8].