The last few sections have talked extensively about aerobic respiration. What defines it as aerobic is its use of oxygen as the terminal electron accepter. Since this is very similar to the type of respiration that humans use, our bias is obvious. Now let me fill you in on a little secret.
Microbes are capable of using all sorts of other terminal electron accepters besides oxygen.
Below we talk about a few examples of anaerobic respiration. The one thing that they all have in common is the use of an electron transport system in a membrane and the synthesis of ATP via ATP synthase. In both nitrate reduction and sulfate reduction there are two types of pathways, assimilatory and dissimilatory. Assimilatory pathways are methods for taking a nutrient in the soil, moving it into the cell and using it for biosynthesis of macromolecules. Dissimilatory pathways use the substrate as a place to dump electrons and generate energy.