ABSTRACT

Bacteria and Archaea can grow in low temperature environments (for example, the Antarctic bacterium Flavobacterium frigidarium isolated from marine sediments can grow at 4°C, as can an archaeon isolated nearby, Methanococcoides burtonii ) as well as high temperature ones. The highest known temperature allowing growth of a Bacterium is 95°C ( Aquifex pyrophilus , isolated from an Icelandic marine thermal vent), while the archaeon Pyrolobus fumarii will grow at 113°C. Bacteria and Archaea are found in most places in the biosphere. They have become adapted to use a wide variety of compounds as sources of energy and carbon, and may be adapted to use those anthropogenically produced chemical compounds as well. The range of metabolic diversity means that 65microorganisms dominate nutrient cycling processes in almost every ecosystem. This role in the cycling of elements has led Bacteria and Archaea to form very close associations with their peers as well as with plants and animals. The close nature of their commensalism, parasitism, and symbiosis mean that pure cultures of many Bacteria and Archaea are extremely difficult to grow in the laboratory. These viable but nonculturable (VBNC) microorganisms can only be detected in biotopes using visualization techniques such as fluorescence in situ hybridization (FISH) or indirect PCR-based methods now known as environmental genomics.