Thermoanaerobacter brockii, formerly Thermoanaerobium brockii, is a thermophilic, anaerobic, spore-forming bacterium.
The bacterium was first isolated from Yellowstone National Park. The growth range for the organism is 35 to 80ðC and pH 5.5-9.5, with optimal growth conditions at 65-70ðC and pH 7.5. T. brockii stains Gram-positive. While originally thought to be non-sporeforming bacteria, it was later discovered that the organism produced spores that can survive heating at 115 ðC for 80 min. The species was originally classified as Thermoanaerobium brockii, but further analysis put the bacteria into the genus Thermoanaerobacter. The species is named "in honor of T.D. Brock, a pioneer in the golden era of thermophily."