The fermentation tests involve the breakdown of carbohydrates to ethyl alcohol, pyruvic acid or lactic acid. Explain what compound is the initial electron donorand what compounds are the final electron acceptor (careful-not products) in fermentation. What tests would you use to determine if an organism was fermentation positive or negative? Include in your answer the indicator you would use. In addition to carbohydrate, what other major organic material, present in the medium, could be broken down to produce energy and what would be the final color change be used when it is broken down?. Also indicate the three possible color changes of the indicator used and the three pH levels at which the medium changes color. Explain the purpose of the Durham or fermentation tube in the test tube and why it is upside down? What gas is produced in fermentation of glucose? The purpose of the fermentation tests are to determine members of what family from other gram negative organisms? Name a genera of Gram-positive cocci from a genera of Gram positive cocci which is a non-fermenter.