Life in High-Temperature Environments: Modern-Day Analogs of Early Earth Still Relevant Today

Abstract

The discovery of new single-celled organism lineages has been remarkable since the adoption of molecular genetics and the discovery of the domain Archaea (Woese et al., 1990). Prior to molecular techniques that initially emphasized the sequences of ribosomal genes (e.g., 16S rRNA), the discipline of microbiology relied nearly entirely on cultivation and the ability to grow a specific microorganism in pure culture under defined conditions. This meant that only microorganisms that grew easily under laboratory conditions were cultivated, and, in many cases, these often rapidly growing organisms do not correspond to the more numerous and relevant microbes that actually inhabit different microbiomes. We now appreciate that many of the microorganisms easily grown under laboratory conditions are often related to their more abundant and important relatives found in situ, but they generally do not exhibit the same functional attributes as numerically relevant microorganisms.