The respiration in bacteria is basically of two types aerobic and anaerobic which may be obligate or facultative. They are further classified as:
Obligate aerobes: These are strict aerobes that mean they always require oxygen for their survival. They are not able to withstand anaerobic conditions.
Facultative anaerobes: These are not of strict types. They normally respire aerobically but can shift to anaerobic types, if conditions are not suitable.
Obligate anaerobes: These are again strict types of anaerobes. They can survive only if oxygen is deficient but are not able to withstand if oxygen is present.
Facultative aerobes: These are bacteria which normally respire anaerobic but can move to aerobic conditions, if the situation demands.
