Bacterial microcompartments, or BMCs, are 80-200nm, enzyme-encompassing organelles composed of interlocking proteins that form cyclical hexamers with a small central pore. Clostridium phytofermentans or Cphy, is a Gram-positive, rod shaped, anaerobic soil microbe that has the ability to not only break down multiple polysaccharides simultaneously but also proceeds to ferment them into biofuels. The genome of Cphy contains 3 BMC loci. During growth on fucose and rhamnose, one of these loci is highly expressed and microcompartments can be viewed using TEM. Under these growth conditions, three products, ethanol, propanol and propionate, which could potentially be highly useful in the biofuel and bioproducts industries, are produced. Gene expression microarrays have revealed that the genes for the fucose/rhamnose-related microcompartment are also highly expressed on D-arabinose. The role of BMCs during growth on D-arabinose has not been reported in any organism. My goal is to determine the role of BMCs in D-arabinose metabolism in C. phytofermentans.