methods for determining acitha of dilution blanks is called the 11. A special Sl
ID: 259541 • Letter: M
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methods for determining acitha of dilution blanks is called the 11. A special Sllue facilitates microscopic cell counting because it has a grid pattern and the amount of sample delivered to the grid is known. 12. Cell turbidity can be measured in an equipment called C. Enumeration: 1. Any artificial culture medium (solid or liquid) for the cultivation of microorganisms requires that the medium must supply all the nutritional and energy requirements necessary for growth. Name four basic requirements supplied in all culture media. b. d. a. Name four types of media used for cultivating and growing microorganisms. b. Name three direct methods for determining the growth or number of bacterial cells in a 2. 3. sample b. C. 4. Name three indirect methods for determining the growth of bacterial cells in a sample. 5. Name the 2 groups of organisms based on their carbon requirement. 6. Give or name 2 reasons/examples why it is often essential to determine the number of b. a. b. bacteria in a sample. a.Explanation / Answer
1. A. carbon source such as glucose
B. peptone and yeast extract as a nitrogen source
C. minerals, vitamins and growth factors
D. water
2. a. Minimal media: Minimal media are those that contain the minimum nutrients possible for the growth of wild-type organisms. Minimal media contains a carbon source, basically glucose, various inorganic salts and water.
b. Enriched media: Enriched medium contains some component that permits the growth of specific types bacteria. Example: blood agar, facilitates the growth of fastidious microbes.
c. Selective media: A selective media is one which has a component added to it which inhibits the growth of certain types of species and promotes the growth of desired species.example: mannitol salt agar, MacConkey agar.
d. Differential media: A differential culture medium allows distinguishing between different types of bacteria based on the observable trait in their pattern of growth on the medium. Example: blood agar to distinguish between hemolytic and non-hemolytic bacteria.
3. a. Microscopic counts: in this method, bacterial cell diluted and viewed under a microscope.
b. Most probable number (MPN):
c. Standard plate count (SPC): used to calculate the number of bacteria on agar plate by spreading technique.
d. Petroff-Hauser chamber: it consists of the grid which is used to count the bacterial number.
Answer 4: a. Indirect Metabolic Activity: it is used to estimate the number of cells by measuring metabolic changes.
b. Indirect Dry Weight
c. Indirect turbidity (biomass)
Answer 5: A. Autotrophs: bacteria that use CO2 as a sole source of carbon
B. Heterotrophs: Bacteria that use organic carbon
Answer 6: A. bacteria cell population increase with time, by measuring the number of bacteria in a sample, growth curve can be developed.
B. it is also used in food and dairy microbiology.
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