<P> An aerobic organism or aerobe is an organism that can survive and grow in an oxygenated environment . In contrast, an anaerobic organism (anaerobe) is any organism that does not require oxygen for growth . Some anaerobes react negatively or even die if oxygen is present . </P> <Ul> <Li> Obligate aerobes need oxygen to grow . In a process known as cellular respiration, these organisms use oxygen to oxidize substrates (for example sugars and fats) and generate energy . </Li> <Li> Facultative anaerobes use oxygen if it is available, but also have anaerobic methods of energy production . </Li> <Li> Microaerophiles require oxygen for energy production, but are harmed by atmospheric concentrations of oxygen (21% O). </Li> <Li> Aerotolerant anaerobes do not use oxygen but are not harmed by it . </Li> </Ul> <Li> Obligate aerobes need oxygen to grow . In a process known as cellular respiration, these organisms use oxygen to oxidize substrates (for example sugars and fats) and generate energy . </Li> <Li> Facultative anaerobes use oxygen if it is available, but also have anaerobic methods of energy production . </Li>

How aerobic and anaerobic conditions affect bacterial growth