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Unformatted text preview: OBTAINING PURE CULTURES Most samples from natural conditions contain many different species of bacteria, and often other types of microbes as well. Each microbe placed on the surface of a solid medium grows and forms a visible colony. Colonies formed by different microbes may have different appearances. In obtaining, a pure culture, one that contains only one type of microbe, the goal is to thin out the original microbes so that the resulting colonies are separate from each other. This can be done in several ways: 1. Streak plate 2. Pour plate 3. Spread plate 4. Micromanipulator METHODS OF PRESERVING BACTERIAL CULTURES 1. Refrigeration—short-term 2. Deep-freezing in liquid suspending medium-- temperature quickly lowered to -50 o C to -95 o C. Years. 3. Lyophilization (freeze-drying)—microbes are quickly frozen while the water content is removed at the same time (formation of ice crystals is damaging to cells). The result is a dry removed at the same time (formation of ice crystals is damaging to cells)....
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This note was uploaded on 01/23/2012 for the course MCB MCB2010 taught by Professor Smith during the Fall '09 term at Broward College.
- Fall '09