A rod-shaped, endospore-forming, Gram-positive bacterium that belongs to the division Firmicutes.
It is thermophile, and lives mostly in soil, hot springs, and ocean sediments.
It can also cause spoilage in food products.
Word origin: bacillus » LL, var. of L bacillum (dim. of baculum) staff, walking stick + stearothermophilus » Gk stéar-, fat, grease + thermophilus, Gk, comb. form of thermós hot, thérmé heat + New Latin –philus, from Greek –philos, beloved, dear, from philos, beloved, loving.
Variant: Geobacillus stearothermophilus