1. Samples of a microbial colony obtained from the natural environment are not pure culture. They are mixed cultures because the environment consists of an array of microorganisms and not one specific organism. A sample obtained from the natural environment such as water or soil may contain several species of microbes that need to be further isolated to obtain a pure culture.
2. Isolation streak plate technique involves the dilution of the sample several folds and then streaking a small amount using a sterile inoculation loop on an agar plate in a zig-zag manner. This is done to obtain a pure culture of bacteria from a mixed population by separating the microprocessor. When the sample is diluted into a small concentration and is streaked onto agar placed, widely spaced, discrete colonies of bacteria can be observed. These isolated colonies can be further cultured to obtain pure cultures by picking and re-streaking them on fresh agar plates.
3. A microbial colony is considered a pure culture because it consists of single species. A single species of bacteria cluster and form an isolated colony on an agar plate which can be further plated on fresh medium.
3-1 - If your agar plate shows discrete uncluttered colonies then you have obtained an isolated colony. The following picture might help you to understand.
3-2. If you subculture isolated microbes into a sterile nutrient broth without any contamination, it will still be considered pure culture because it is single isolated species in a sterile aseptic environment of the nutrient broth.
3.3. A pure culture can become a mixed culture due to contamination. This could be caused by airborne bacteria if your conditions are not aseptic. Contamination is possible if the work area is not clean and sterile or if the glassware is not sterile. The contamination can transform your pure culture into a mixed culture and is hence problematic. So, it is very important to maintain a sterile and aseptic environment, glassware, and instruments.
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Answer:
Booker T. Washington
Explanation:
As part of the 1940 Famous Americans Issue, the U.S of America issued the 10-cent Booker T. Washington stamp on April 7, 1940. Its significance lies in the fact that it was the 1st time a former African American slave has been honored on a postage stamp in the country. Only 35 Americans were honored by the Famous Americans Issue based on their significant contributions to the different fields like that of poetry, technology, music, literature, education, art, etc and decision eventually agreed by Franklin Delano Roosevelt.
Answer:
Agriculture, Food and Natural Resources.
Architecture and Construction.
Education and Training.
Business Management and Administration.
Arts, Audio/Video Technology and Communications.
Finance.
Government and Public Administration.
Health Science.
Explanation:
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The answer is New York city
