A microorganism which can make its own food using chemicals like ammonia or sulfur compounds rather than solar energy as in photosynthesis. It derives its energy by oxidizing the chemical bonds. A type of autotroph. This type of organism is also known as a "chemolithotroph" or "chemotroph" in some scientific literature.
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.