What distinguishes autotrophic from heterotrophic bacteria? Are more bacteria anaerobic or aerobic? What are the two types of anaerobic bacteria called and what kinds of environments can each tolerate?
Autotrophic bacteria are photosynthetic, containing chlorophyll a in membrane-bound vesicles, called chromatophores. The majority of bacteria, however, are heterotrophs. Most bacteria rely on aerobic respiration. Some anaerobic bacteria, the obligate anaerobes, rely on fermentation solely and are killed by oxygen. Some anaerobic bacteria, the facultative anaerobes, can carry out either fermentation or respiration depending on whether oxygen is present.
