Why do bacteria respire anaerobically?

Question

Why do bacteria respire anaerobically?

Answer 1

Its simply because most of their work is to be done in conditions with insufficient oxygen present. As oxygen is necessary for aerobic respiration, and without it only anaerobic respiration can take place, bacteria thus have to adapt themselves to respire anaerobically.

Anaerobic respiration is also helpful to bacteria in carrying out the decomposition process.Check it out here:

http://dwb.unl.edu/Teacher/NSF/C11/C11Li...

Thus these are the prominent reasons.

Also you should know that not all bacteria respire this way.  

Answer 2

Anaerobic process is a chemical or biological process such as decay or decomposition that does not require oxygen. Such processes are often used to dispose of wastes while generating useful gases.

Answer 3

First, not all bacteria use anaerobic respiration. Those that do can survive in environments the others can't thus giving them more opportunities. Also, it's a more efficient way of producing ATP.