Types of Bacteria (Oxygen Requirement)

1. Aerobes

1.1. require oxygen

1.2. use oxygen as a final electron acceptor

1.3. eg: Staphylococcus aureus

2. Microaerophiles

2.1. require limited amount of oxygen

2.2. The excess oxygen - block activities of oxidative enzymes ---> cause death

2.3. eg: Helicobacter pylori

3. Obligate anaerobes

3.1. require absence of oxygen

3.2. use other molecules as final electron acceptor

3.3. metabolise energy by anaerobic respiration or fermentation

3.4. eg: Clostridium tetani

4. Aerotolerant anaerobes

4.1. not use oxygen for growth

4.2. not killed by the presence of oxygen

4.3. not use oxygen as final electron acceptor

4.4. produce catalase or superoxide dismutase

4.5. fermentative organisms

4.6. eg: Lactobacillus

5. Facultative anaerobes

5.1. can grow in present / absence of oxygen

5.2. prefer use oxygen for growth

5.3. In oxygen-poor environment, cellular respiration may occur anaerobically, utilizing such compounds :

5.3.1. nitrates

5.3.2. sulfate

5.4. use sulfate & nitrates as final electron accertor

5.5. eg: Escherichia coli