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2021-05-14

What biosafety level do most introductory microbiology students work with?

What biosafety level do most introductory microbiology students work with?

BSL-1 containment is normally found in water-testing laboratories, in high schools, and in colleges teaching introductory microbiology classes. Work is done on an open bench or in a fume hood. Standard microbiological practices are used when working in the laboratory.

During which growth phase will Gram-positive bacteria be most susceptible to penicillin group of answer choices?

Microbiology

Question Answer
Most bacteria reproduce by binary fission
During which growth phase will gram-positive bacteria be most susceptible to penicillin? log phase
Which of the following is the best definition of generation time? the length of time needed for a cell to divide
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How do salts and sugars preserve foods quizlet?

How do salts and sugars work to preserve foods? By creating a hypertonic environment. The bacteria/fungi will not be able to reproduce, because the salt/sugar will take the water out of the organism. Loss of water causes PLASMOLYSIS : shrinking of the cytoplasm.

Why is salt and sugar used to preserve food?

Like salt water also has an osmotic effect i.e. when foods are placed in a concentrated sugar solution water is drawn out of the cells of foods and microorganisms so that microorganisms can no longer survive.

What are the advantages and disadvantages to the use of phenolic compounds as control agents?

The advantages of phenolic compounds is that they remain one standard against which other (less toxic) phenolic disinfectants are rated. The disadvantage is that phenolic compounds are toxic, which makes them dangerous to use as antiseptics.

Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt group of answer choices?

Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt? Selected Answer: C. peptone and beef extract.

Which cultivation technique yields the best CFU count?

turbidimetry

How do you calculate viable cells?

To calculate viability:

  1. Add together the live and dead cell count to obtain a total cell count.
  2. Divide the live cell count by the total cell count to calculate the percentage viability.

How do you determine the number of colonies?

To find out the number of CFU/ ml in the original sample, the number of colony forming units on the countable plate is multiplied by 1/FDF. This takes into account all of the dilution of the original sample. For the example above, the countable plate had 200 colonies, so there were 200 CFU, and the FDF was 1/4000.

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How do you calculate the number of bacteria in original culture?

Multiply the number of colonies on the plate by 10 to calculate the number of cells per mL of culture from the dilution tube used. Multiply the number from Step 2 by 10^(plate number) to calculate the number of cells per mL of original culture.

How do you calculate the number of bacteria in a colony?

For example, suppose the plate of the 10^6 dilution yielded a count of 130 colonies. Then, the number of bacteria in 1 ml of the original sample can be calculated as follows: Bacteria/ml = (130) x (10^6) = 1.3 × 10^8 or

How many bacteria are in a colony forming unit?

The average CFU count in probiotics is between 1 and 10 Billion CFUs per serving. Some companies even advertise extremely high counts such as over 100 Billion CFUs.

Which method of determining bacterial number is the most accurate?

An easier and more accurate method to determine the microbial count is the plate method, where a food sample is placed on a culture medium plate. After an appropriate incubation period, you can count the number of colonies that have formed on the culture medium plate.

How do you measure bacteria on a surface?

Re: Measuring Bacteria The most common way would probably be to swab your solid surface and then rub that swab over a petri dish with bacterial growth agar. Then you just let the plates incubate and grow. Keep in mind that different types of bacteria grow on different growth mediums and at different temperatures, etc.

Which soap kills the most germs science project?

antibacterial soap

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Which of the following method is used for enumeration of bacteria in vaccines and cultures?

9. Which of the following method is used for enumeration of bacteria in vaccines and cultures? Explanation: Membrane count is used for the enumeration of bacteria in vaccines and cultures. Even electronic enumeration is used in this application.

Which of the following is a direct way of measuring bacterial growth?

Direct- measurement of the growth of microbial populations through measuring cell numbers, measuring the population’s total mass (direct counts on small samples).

Which device is used for the enumeration of bacteria in air?

Capillary impinger : devices of simpler design , used in analysis of several samples of air at the same time.

How do you create a pure culture?

A pure culture is usually derived from a mixed culture (one containing many species) by transferring a small sample into new, sterile growth medium in such a manner as to disperse the individual cells across the medium surface or by thinning the sample manyfold before inoculating the new medium.

What are three methods commonly used to derive a pure culture?

Enrichment Culture Method.

  • Streak Plate Method: This method is used most commonly to isolate pure cultures of bacteria.
  • Pour Plate Method:
  • Spread Plate Method:
  • Serial Dilution Method:
  • Single Cell Isolation Methods:
  • Enrichment Culture Method:

Why is it necessary to prepare a pure culture?

The importance of having a pure culture, and not a mixed culture, when performing biochemical testing is that a pure culture may react much differently in isolation than when it is combined with other species. Bacteria replicates at infinitesimally long rates and one species may enforce or weaken the other.

What is a pure culture and why is it important?

The isolation of bacteria in pure culture is important because it facilitates the application of recombinant DNA technology through the isolation of clones.