Final answer:
Facultative anaerobes, like E. coli, can grow both aerobically and anaerobically because they can switch between aerobic respiration and fermentation or anaerobic respiration. Dense growth at the surface and turbidity throughout a thioglycolate medium culture tube indicates facultative anaerobes. Testing in different oxygen environments is crucial to determine facultative anaerobe characteristics.
Step-by-step explanation:
Based on the observed growth patterns for the facultative anaerobe on blood agar incubated aerobically, blood agar incubated anaerobically, and chocolate agar incubated in a CO2 incubator, we can draw conclusions about the oxygen requirements of the bacteria in question. Facultative anaerobes like E. coli show growth in both the presence and absence of oxygen, because they can switch between aerobic respiration and fermentation or anaerobic respiration.
An inoculated thioglycolate medium culture tube that shows dense growth at the surface and turbidity throughout the rest of the tube indicates that the organisms are facultative anaerobes (Answer B to question 11). This is because facultative anaerobes exhibit better growth in the presence of oxygen but will also grow without it.
Bacteria such as facultative anaerobes are capable of utilizing different pathways to generate energy depending on the availability of oxygen; therefore, when performing tests to determine the physiological oxygen requirement for a bacterium, it is essential to observe growth in various environments. In the case of facultative anaerobes, the ability to grow under both aerobic and anaerobic conditions is a key characteristic.