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Unformatted text preview: Microbial measurements. In order to measure the number of bacteria in a population, various methods are available. In one method, known as the plate count method , a sample of bacteria is diluted in saline solution, distilled water, or other holding fluid. Samples of the dilutions are then placed in Petri dishes with a growth medium and set aside to incubate. Following incubation, the count of colonies is taken and multiplied by the dilution factor represented by that plate. Generally, plates with between 30 and 300 colonies are selected for determining the final count, which is expressed as the number of bacteria per original ml of sample. Another measuring method is to determine the most probable number. This technique is often used to determine the number of bacteria in a sample of contaminated water. Water samples are added to numerous tubes of single-strength and double-strength lactose broth. If coliform bacteria added to numerous tubes of single-strength and double-strength lactose broth....
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This note was uploaded on 11/11/2011 for the course BIO 101 taught by Professor Pesthy during the Fall '07 term at Texas State.
- Fall '07