In this experiment the purpose is to seek understanding between an organism and its use of oxygen. Oxygen is a very important part of the organisms’ survival. Oxygen has a tendency to form very reactive by-products inside a cell. These by-products create havoc by reacting with protein and DNA, thus inactivating them. Cells that are able to live in the presence of oxygen have evolved enzymes to cope with H2O2 and O2- and thus are not inhibited by O2. Also many anaerobes have oxygen labile Fe-S centers and no cellular machinery to protect them from the oxidizing power of oxygen. Organisms that cannot deal with the problems presented by oxygen cannot survive in air and are killed (Anaerobic Organisms Wikipedia). On the basis of oxygen tolerance, microorganisms can be placed into four classes. Strict aerobes cannot survive in the absence of oxygen and produce energy only by oxidative phosphorylation.Strict anaerobes, in many cases, generate energy by fermentation or by anaerobic respiration and are killed in the presence of oxygen Aerotolerant anaerobes generate ATP only by fermentation, but have mechanisms to protect themselves from oxygen. Faculatative anaerobes prefer to grow in the presence of oxygen, using oxidative phosphorylation, but can grow in an anaerobic environment using fermentation. (Fundementals of Microbiology p. 105) Oxygen utilization is a primary diagnostic tool when identifying microorganisms. Special media has been developed for the purposes of determining the oxygen relationship and method of fermentation vs. respiration of microorganisms. One such medium, Thioglycollate Broth is useful for determining the oxygen relationship of a microorganism. The medium contains thioglycollic acid, cystine and agar, among other things. (Anaerobic Organisms Wikipedia).The thioglycollic acid and agar prevent oxygen from entering the entire medium. The medium used was a plate of TSA +glucose, one incubated anaerobically in a...
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