Question

Aerotolerant anaerobes and facultative anaerobes have growth patterns in thioglycollate that are similar. Based on your understanding of aerotolerant versus facultative anaerobes, how could you differentiate between the two?

I know the definitions of aerotolerant and faculative anaerobes, the question is asking how you would differentiate between the two in thioglycollate. How could a student in a micro class differentiate between the two.

Answer 1

Aerotolerant anaerobes are actually anaerobes but can cope up even in the presence of oxygen. It doesnt use oxygen for growth.

Facultative anaerobes can grow both in the presence of oxygen and in its absence. It prefers oxygen rather than its absence. SO it shifts its growth where it gets more of oxygen.

So in a thioglycollate broth, aerotolerant anaerobes starts growing from the bottom and then spreads evenly in the tube because oxygen has no effect on it and facultative anaerobe grows both in top and bottom but more of growth or turbidity is seen towards the top of the tube where oxygen is present. Turbidity (more growth) is much more in facultative anaerobe growth when compared to aerotolerant anaerobe.