Fatty acid oxidation

Fatty acids can be used as substrates for microbial metabolism. The metabolic process is called b-oxidation and it occurs in the mitochondria of eukaryotes or the cytoplasm of prokaryotes. Two-carbon units are removed from the fatty acid to yield their acyl CoA. The pathway starts with the activation of the fatty acid through CoA. There  then follow two separate dehydrogenation reactions where electrons are transferred to FAD and  NAD+ finally yielding CoA and  an activated fatty acid to restart the  cycle. The complex series of reactions for fatty acids with odd or even numbers of carbons and saturated or unsaturated bonds between them are described in detail in various biochemistry textbooks including Instant Notes in Biochemistry.