There is a world within ours populated with an extraordinarily rich diversity of life who’s total biomass exceeds that of all plants and animals on Earth (Whitman et al., 1998). This world however is invisible to the naked eye, only when looked at closely under a microscope can you see that this world belongs to bacteria. There is an estimated 4-6 x 10³⁰ bacterial cells on Earth thriving in a great variety of habitats within the terrestrial and marine environments (Whitman et al., 1998). These habitats extend from the cold Polar Regions to hot volcanic springs (Fig. 1) (Niehaus et al., 1999), in the shallow sunlight waters of the ocean to the deep depths of the sea bed, and subsurface to the greatest depths sampled within the Earth’s crust (Kelley et al., 2002). They can even be found within humans as the human body is a host to more than 100 trillion microbes including bacteria that together aid with digestion in the gut (Costello et al., 2009).
The extensive distribution of bacteria across a phenomenal range of different habitats is due to the exceptional genetic diversity of bacterial cells, allowing different bacterial species to occupy many different niches (Whitman et al., 1998). This high genetic diversity has allowed bacteria to evolve adaptions to living in even the most extreme habitats that would otherwise prove inhospitable to most other organisms (Caganella & Wiegel, 2011). Bacteria living in extreme habitats are able to survive extremes in temperature from boiling to freezing, very acidic (pH 0-3) or very alkali (pH 10-12) conditions, very high salinities of 5-30%, high pressure, elevated radiation levels and high solvent/metal concentrations (Niehaus et al., 1999; Kelley et al., 2002; Canganella & Wiegel, 2011).
This blog will explore why bacteria are so genetically diverse resulting in their colonization of a vast array of habitats and will highlight the extreme nature of one of the most challenging habitats on Earth that bacterial populations have been found thriving in. The importance of bacteria within this habitat and also their significance in the origin of life will be discussed which will to help answer whether the stigma surrounding bacteria is truly deserved?