Complex sentence: Two main groups of autotrophic nitrifying bacteria are responsible for carrying out nitrification and possess the ability to use the energy available from the inorganic compounds of ammonia or nitrate to create organic compounds.
Split into simpler sentences: Two main groups of autotrophic nitrifying bacteria are responsible for carrying out nitrification. These bacteria possess the ability to use the energy available from the inorganic compounds of ammonia or nitrate to create organic compounds.