Bacteria are a highly diverse group of organisms owing to their billions of year’s long evolutionary history on Earth throughout which rapid reproduction, mutations and genetic recombination have developed many new adaptions that promote survival in many different habitats. Bacteria have even been found flourishing in one of the most extreme habitats ever to have been discovered known as hydrothermal vents occurring along mid-ocean ridges at thousands of metres depth where super-heated, toxic clouds of hydrothermal fluid issues from chimneys several meters in height in the darkness of the deep sea. These bacteria have been able to harness the ability to create energy from the oxidisation of hydrogen sulphide carried within the hydrothermal fluid to synthesise organic carbon and amino acids in a process known as chemosynthesis. Chemosynthetic bacteria are therefore the primary producers of this ecosystem supporting the rich diversity of life that has been found to exist at hydrothermal vents, which depend on these bacteria for nutrition.
The oldest fossil ever to have been found was bacteria within a volcanogenic massive sulphide deposit which are commonly found at mid-ocean ridges. The discovery of this fossil and the new found understanding of hydrothermal vents have led to the theory of a chemosynthetic origin of life by bacteria at hydrothermal vents. While this theory is controversial, the simple prokaryotic structure of a bacterial cell is thought to have originated first on Earth.
It can conclusively be said therefore that bacteria are very important in supporting life discovered at hydrothermal vents and possibly supporting the very beginning of life on Earth, without which there may have been no life at all. Their form of reproduction and their high reproductive rate has to be admired as it is what has led to their high genetic diversity and therefore their ability to be successful in many different habitats, which so far they are the only organisms discovered with the ability to do this. Bacteria have therefore been shown to be highly important organisms and should be viewed with much greater respect than their current reputation as harmful disease causing pathogens that precedes them.