For years, developmental biology has been in search of an understanding as to how an organism undergoes cellular differentiation to produce distinct cell types. Bacillus subtilis is a bacterial organism that undergoes cellular differentiation during a process known as sporulation. B. subtilis is the most studied spore-forming bacterium and is used as a model for cell fate and development. Without carbon source availability, B. subtilis must turn to other sources of carbon in order to create the energy needed for the process of sporulation. One operon in its genome that may be devoted to the breakdown of fatty acids for energy during sporulation is the mother cell metabolic gene (mmg) operon. This operon consists of mmgABCDE and yqiQ, all of which are presumably involved in either fatty acid metabolism or the (methyl)citric acid cycle. Two genes in this operon, mmgC and mmgB show similarity to acyl-coenzyme A dehydrogenase and (beta)hydroxyacyl-coenzyme A dehydrogenase, respectively. Both mmgC and mmgB have been successfully cloned, overexpressed, and purified from B. subtilis strain 168. MmgC has also been biochemically characterized and determined to be a short chain acyl-coenzyme A dehydrogenase. Furthermore, MmgC shows specificity toward isobutyryl-coenzyme A over butyryl-coenzyme A. MmgB, on the other hand, did not show any activity for the dehydrogenation of (beta)hydroxybutyryl-coenzyme A.
