OXYGEN REQUREMENTS OF MICROBES - 4 Aerotolerant microbes...

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OXYGEN REQUREMENTS OF MICROBES 1. Obligate aerobes  (aerobic microbes)—these require oxygen to live and grow (this description  also fits us!). They must produce enzymes that counteract the toxic effects of oxygen. The  advantage of using oxygen is that aerobic cellular metabolism is the most efficient way to  produce energy. 2. Facultative anaerobes —can live and grow well either with or without oxygen. However,  energy production is more efficient with oxygen present. These must produce protective  enzymes.  With oxygen available--aerobic cellular respiration Without oxygen--fermentation 3. Obligate anaerobes  (strict anaerobes)—do not use oxygen in their metabolic reactions and  cannot live in its presence. These do not carry the genes for making the protective enzymes.  Energy is produced by fermentation or anaerobic cellular respiration. 
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Unformatted text preview: 4. Aerotolerant microbes —do not use oxygen but can at least partly neutralize its toxic effects, so they can grow fairly well to very well in its presence. Energy is produced mainly by fermentation. 5. Microaerophiles —must have oxygen but in very low levels. These require a little in at least some of their metabolic reactions but cannot tolerate normal atmospheric levels. Energy is produced by fermentation. The technique we use in lab to show these differing requirements is a special growth medium called fluid thioglycolate medium. This is placed in a deep test tube. It contains a very small concentration of agar to thicken it slightly, plus a chemical called sodium thioglycolate to tie up free oxygen. It is described as a reducing medium....
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