Chemoautotrophic bacteria are

All autotrophs are primary producers. Autotrophs are the organisms that use inorganic carbon (carbon dioxide) as a carbon source for the formation of organic compounds. Autotrophs harvest light or chemical energy and store that energy in carbon compounds. Most autotrophs are photoautotrophs (e.g., plants, algae, and photosynthetic bacteria) and use sunlight for this process. Chemoautotrophic bacteria obtain their energy from oxidising inorganic compounds (e.g., hydrogen sulphide, iron, ammonia and nitrites).