Experiment 4: Isolation of Individual Colonies
For the experiment, isolation of individual colonies I was allowed to compare enriched, complex, and synthetic media. Enriched media contains some important growth factors necessary for growth of specific organisms or an organism that has a complex nutritional requirement. This "growth factor" contains vitamins, amino acids, blood components, or carbon sources. Enriched media is used to harvest as many different types of microbes as are present in a specimen. These are commonly used for blood cultures. Complex media is a mixture of proteins and extracts in which the exact amount of a particle amino acid, sugar, or other nutrients is not known. These are used for growing hetrotrphic organisms. Examples of hetrotrophic organisms include fungi, protozoa, and animals. Synthetic media is also known as “chemically defined” media. The exact amount of pure chemicals that are used to formulate the media are known. This is used in in vitro cell culture for humans and animals.
Selective and differential media were examined as well. Selective media allows for selection of a particular microorganissm that may be present in a mixed culture. This contains a compound that enhances the growth of the desired organism or inhibits growth of competing organisms. Selective media contains antimicrobial substances or dyes to inhibit unwanted organisms from growing. These are frequently used to test antibiotic resistance. For example, if you are testing a microbe that is resistant to ampicillin, ampicillin can be added to the media. This will kill all the rest of the unwanted organisms. Differential media allows for the separation of organisms based on some observable change in the appearance of the media or by an observerable effect on the microbe. Differential media is a little different in the fact that it does not kill the microbes like