What is the purpose of replica plating?
The purpose of replica plating is to be able to compare the master plate and any secondary plates, typically to screen for a desired phenotype.
Why is a velvet surface used in replica plating?
Velvet Pad is a consumable that is used with the Replica Plating Apparatus and allows of colony transfer from Agar Plate while retaining the colony orientation. Used for screening auxotrophy and antibiotic resistance.
Which of the mechanisms would most likely be involved in repairing a single point mutation?
Which of the following mechanisms would most likely be involved in repairing a single point mutation? Insertion of one nucleotide in a gene will lead to a frameshift mutation.
What is master plate in microbiology?
(i) Bacterial cultures are diluted, and the cells are spread on the surface of semisolid nutrient agar medium in a Petri dish (called “master plate”). The medium in the master plate is a complete medium i.e., containing all the nutritional components required by the bacterial population.
What is meant by plating?
Plating is a surface covering in which a metal is deposited on a conductive surface. Jewelry typically uses plating to give a silver or gold finish. Thin-film deposition has plated objects as small as an atom, therefore plating finds uses in nanotechnology. There are several plating methods, and many variations.
What is plating method in microbiology?
This technique typically is used to separate microorganisms contained within a small sample volume, which is spread over the surface of an agar plate, resulting in the formation of discrete colonies distributed evenly across the agar surface when the appropriate concentration of cells is plated.
What is the advantage of pour plate method?
The most common method for determining the total viable count is the pour-plate method. The pour plate technique can be used to determine the number of microbes/ mL in a specimen. It has the advantage of not requiring previously prepared plates and is often used to assay bacterial contamination of foodstuffs.
What is the difference between pour plate and spread plate method?
The main difference between pour plate and spread plate is that the molten agar is poured on to the inoculum during the preparation of the pour plate whereas inoculum is spread on the surface of the solidified agar during the preparation of the spread plate.
What is the difference between streak plate and spread plate technique?
The key difference between streak plate and spread plate is that the streak plate is used to isolate and purify a particular bacterial species from a mixture of bacteria while the spread plate is used to enumerate and quantify bacteria in a sample.
What is pour plate technique?
Pour plate method is usually the method of choice for counting the number of colony-forming bacteria present in a liquid specimen. In this method, fixed amount of inoculum (generally 1 ml) from a broth/sample is placed in the center of sterile Petri dish using a sterile pipette.
What are the advantages and disadvantages of streak plate method?
Streak plating is a microbiology laboratory method that has two major disadvantages. Firstly, users will not be able to grow obligate anaerobes using this method. Secondly, only organisms that were viable in the original sample are able to be grown.
How can a streak plate become contaminated?
How can a streak plate become contaminated? If the loop is not sterilized. If you drop the plate. If lid isn’t on.
Why is it important to use a sterilized loop between streaks when preparing a streak plate?
Flame the loop or use a new disposable loop after you streak each quadrant. Using a new or sterilized loop allows you to effectively dilute the inoculum on the plate and obtain isolated colonies by spreading the inoculum thinner and more evenly.
How can you tell if a streak plate is contaminated?
If some of your agar plates become contaminated, you can often tell by examining the plate how contamination took place. If the contaminants are imbedded in the agar, the contaminant was probably poured with the medium.
Why must you Flame the loop between streaks?
Flaming the loop between streaks ensures that the loop starts clean and that only this small amount of bacteria is used to inoculate the next quadrant.
What happens if you don’t flame the loop in between quadrants?
What is a bacterial colony? What would happen if you forgot to sterilize your loop in between each quadrant streak? You would spread a lot of bacteria back into quadrant one and probably not see isolated colonies.
What is an advantage of the four quadrant streaking method?
In order to obtain well-isolated discrete colonies, the quadrant streak technique should be used. This allows sequential dilution of the original microbial material (broth culture or colonies on a plate or slant) over the entire surface of a fresh plate.
What is the most important reason to streak for isolation?
As you might guess, the purpose of streaking for isolation is to produce isolated colonies of an organism on an agar plate. This is useful when you need to separate organisms in a mixed culture or when you need to study the colony morphology of an organism.
Can some bacteria grow on the streak plate and not be seen?
After incubation, bacterial growth is visible as colonies in and on the agar of a pour plate. Can some bacteria grow on the streak plate and not be seen if the pour plate technique is used? Yes, the pour plate is O2 limited. Thus, some bacteria will only grow on the streak plate as it provides ample O2.
How do you streak bacteria on agar plates?
- Hold loop with bacterial sample parallel to fresh plate.
- Gently rub loop across surface spreading bacteria thinly throughout.
- Flip loop on other side or even gently drag edges across plate if visible bacteria still needs to be delivered.
What advantages does the streak plate method have over the pour plate method?
What advantage does the streak plate method have over the pour-plate method? The streak plate method does not require any additional media for dilution and only requires one plate for inoculation.
What is the purpose of ethanol in spread plate technique?
What is the purpose of the ethanol in the spread-plate technique? Kills off bugs on “L” shaped spreader before putting it into contact with the spread plate. You just studied 6 terms!
Was the streak plate method effective at diluting the population size in both plates?
The streak plate method was effective at diluting the population size in all four plates because it is a rapid isolation method and it also allowed for easier observation of the bacteria. The streak plate method is also a useful tool for obtaining the color of certain substances.
Why must you invert plates during incubation?
Petri dishes need to be incubated upside-down to lessen contamination risks from airborne particles landing on them and to prevent the accumulation of water condensation that could disturb or compromise a culture.
What happens if you incubate bacteria too long?
If a bacterial culture is left in the same media for too long, the cells use up the available nutrients, excrete toxic metabolites, and eventually the entire population will die. Thus bacterial cultures must be periodically transferred, or subcultured, to new media to keep the bacterial population growing.
Why do you have to invert the plate and why do you have to incubate the plates overnight at 370c?
10. 5 Plates are incubated upside down (agar up), so that condensation does not drip onto the plate and interfere with the developing microbes.
Do all culture media need to be sterilized before?
When microbiological media has been made, it still has to be sterilized because of microbial contamination from air, glassware, hands, etc. Within a few hours there will be thousands of bacteria reproducing in the media so it has to be sterilized quickly before the microbes start using the nutrients up.
What are the 4 methods of sterilization?
Classical sterilization techniques using saturated steam under pressure or hot air are the most reliable and should be used whenever possible. Other sterilization methods include filtration, ionizing radiation (gamma and electron-beam radiation), and gas (ethylene oxide, formaldehyde).
How do you sterilize culture media?
Although sterilization of culture media is best carried out in a steam autoclave at temperatures between 121-134°C it has to be recognised that damage is caused to the medium by the heating process.
Why do we autoclave at 121 degree Celsius?
Temperature. The standard temperature for an autoclave is 121 degrees Celsius. The reason for this is that simply bringing something up to the temperature of boiling water, 100 degrees Celsius (212 degrees Fahrenheit), is not sufficient to sterilize it because bacterial spores can survive this temperature.