These resist a range of hazardous environments, and protect against heat, radiation, and desiccation. All these bacteria are 'anaerobic'. The aerobic sporing bacteria can also cause disease. Anthrax is caused by Bacillus anthracis . Bacillus cereus causes two types of food poisoning.
Some bacteria have an absolute requirement for oxygen.
These are the obligate aerobes . Others, the facultative anaerobes can survive in the absence as well as the presence of oxygen. The obligate anaerobes are killed by traces of oxygen. A small group of bacteria are killed by normal atmospheric levels of oxygen, but yet require traces of oxygen to grow. These are the referred to as microaerophiles .