Propionibacterium is a gram-positive, anaerobic bacterium that exists naturally in the rumen of herbivores. It is the major microorganisms used in the process of making swiss cheese; the characteristic flavor of swiss cheese derives from propionate and the holes are derived from carbon dioxide. Propionibacterium, aptly named, produces a large amount of propionate. Propionibacterium first converts hexoses via glycolysis to pyruvate. The pyruvate is then converted to a molecule called propionate shown below. Two intermediate steps in this propionate producing pathway requires the enzymes succinate dehydrogenase and malate dehydrogenase working in the reverse of the citric acid cycle direction. What is the general term given to the process by which Propionibacterium convert pyruvate, the end product of glycolysis into propionate? Why is this process required and what steps are critical for survival of the Propionibacterium organism?