Meiothermus
Meiothermus is a genus of bacteria in the Thermaceae family, within the Deinococcota group. They are moderately thermophilic, growing best at about 50–60°C and in alkaline to neutral pH (roughly 7.5–9.5). Meiothermus are strictly aerobic and mostly Gram-negative chemoorganoheterotrophs, meaning they use organic compounds for energy and carbon; some species can use nitrate as an electron acceptor.
Key differences from the closely related Thermus genus include a cooler growth range and distinct molecular markers. Meiothermus generally has two glycolipid bands in its membrane (Thermus has one). Genetically, Meiothermus has three conserved signature indels (CSIs) in specific proteins (5-methyltetrahydrofolate–homocysteine methyltransferase, a cadmium transporter, and polynucleotide phosphorylase) that are unique to this genus, whereas Thermus has eight CSIs.
Meiothermus was first isolated from alkaline and neutral hot springs in Kamchatka, Russia, and Yellowstone National Park, USA. Most species are red in color; M. chilarophilus is yellow. Some species can form biofilms and attach to surfaces. They can use substrates such as starch, disaccharides, and amino acids for carbon and energy, and some can degrade keratin, releasing amino acids into the environment. They also inhabit the guts of certain Antarctic polychaete worms, where they contribute to the microbiome and produce antifreeze proteins that protect cells from ice.
Representative species include Meiothermus ruber (the type species), M. cateniformans, M. cerbereus, M. granaticius, M. hypogaeus, M. luteus, M. rufus, M. taiwanensis, and M. rosaceus, among others.
This page was last edited on 3 February 2026, at 12:42 (CET).