 thumb|250px|thermophilic organisms chloroflexus aurantiacus is a photosynthetic bacterium isolated from hot springs, belonging to the green non-sulfur bacteria. this organism is thermophilic and can grow at temperatures from 35&nbsp;Â°c to 70&nbsp;Â°c. chloroflexus aurantiacus can survive in the dark if oxygen is available. when grown in the dark, chloroflexus aurantiacus has a dark orange color. when grown in sunlight it is dark green. the individual bacteria tend to form filamentous colonies enclosed in sheaths, which are known as trichomes. ==physiology== as a genus, chloroflexus spp. are gram negative filamentous anoxygenic phototrophic (fap) organisms that utilize type ii photosynthetic reaction centers containing bacteriochlorophyll a similar to the purple bacteria, and light-harvesting chlorosomes containing bacteriochlorophyll c similar to green sulfur bacteria of the chlorobi. as the name implies, these anoxygenic phototrophs do not produce oxygen as a byproduct of photosynthesis, in contrast to oxygenic phototrophs such as cyanobacteria, algae, and higher plants. while oxygenic phototrophs use water as an electron donor for phototrophy, chloroflexus uses reduced sulfur compounds such as hydrogen sulfide, thiosulfate, or elemental sulfur. this belies their antiquated name green non-sulfur bacteria, however chloroflexus spp. can also utilize hydrogen(h2) as a source of electrons. chloroflexus aurantiacus is thought to grow photoheterotrophically in nature, but it has the capability of fixing inorganic carbon through photoautotrophic growth. instead of using the calvin-benson-bassham cycle typical of plants, chloroflexus aurantiacus has been demonstrated to use a novel autotrophic pathway known as the 3-hydroxypropionate pathway. the complete electron transport chain for chloroflexus spp. is not yet known. particularly, chloroflexus aurantiacus has not been demonstrated to have a cytochrome bc1 complex, and may use different proteins to reduce cytochrome c ==evolution of photosynthesis== one of the main reasons for interest in chloroflexus aurantiacus is in the study of the evolution of photosynthesis. as terrestrial mammals, we are most familiar with photosynthetic plant
Phototrophic_bacteria