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These organisms perform photosynthesis through organelles called chloroplasts and are believed to have originated about 2 billion years ago. [1] Comparing the genes of chloroplast and cyanobacteria strongly suggests that chloroplasts evolved as a result of endosymbiosis with cyanobacteria that gradually lost the genes required to be free-living.
Other organisms, called heterotrophs, take in autotrophs as food to carry out functions necessary for their life. Thus, heterotrophs – all animals , almost all fungi , as well as most bacteria and protozoa – depend on autotrophs, or primary producers , for the raw materials and fuel they need.
Some bacteria are limited to only one nutritional group, whereas others are facultative and switch from one mode to the other, depending on the nutrient sources available. [16] Sulfur-oxidizing , iron , and anammox bacteria as well as methanogens are chemolithoautotrophs , using inorganic energy, electron, and carbon sources.
Organic matter produced by autotrophic bacteria is then used to support the upper trophic levels. The hydrothermal vent fluid and the surrounding ocean water is rich in elements such as iron , manganese and various species of sulfur including sulfide , sulfite , sulfate , elemental sulfur from which they can derive energy or nutrients. [ 9 ]
Chlorobium chlorochromatii, originally known as Chlorobium aggregatum, is a symbiotic green sulfur bacteria that performs anoxygenic photosynthesis and functions as an obligate photoautotroph using reduced sulfur species as electron donors. Chlorobium chlorochromatii can be found in stratified freshwater lakes. [2]
Purple sulfur bacteria (like green sulfur bacteria) typically form blooms in non-thermal aquatic ecosystems, but some members have been found in hot springs. [34] For example Chlorobaculum tepidum can only be found in some hot springs in New Zealand at a pH value between 4.3 and 6.2 and at a temperature above 56 °C (133 °F).
A bacillus (pl.: bacilli), also called a bacilliform bacterium or often just a rod (when the context makes the sense clear), is a rod-shaped bacterium or archaeon. Bacilli are found in many different taxonomic groups of bacteria. However, the name Bacillus, capitalized and italicized, refers to a specific genus of
Starting in 1985, researchers proposed that life arose at hydrothermal vents, [235] [236] that spontaneous chemistry in the Earth's crust driven by rock–water interactions at disequilibrium thermodynamically underpinned life's origin [237] [238] and that the founding lineages of the archaea and bacteria were H 2-dependent autotrophs that used ...