Microbiology Lab Techniques

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Questions and Answers

What is the purpose of using sterile technique when inoculating an agar plate?

To ensure the growth of a single species of bacteria (correct)

To cool the inoculating loop

To sterilize the inoculating loop

To introduce multiple species of bacteria

Why is it important to cool the inoculating loop after heating it in the flame?

To prevent burns to the skin

To prevent killing the bacteria

To sterilize the loop further

To handle the inoculum safely (correct)

What is the purpose of flaming the inoculating loop between each quadrant?

To cool the loop

To sterilize the loop (correct)

To prepare the loop for the next quadrant

To mix the bacteria

Why are agar plates incubated upside down?

To reduce bacterial contamination and prevent water condensation Signup and view all the answers

What is the purpose of labelling an agar plate?

To identify the agar plate Signup and view all the answers

What is the primary goal of aseptic technique in a laboratory setting?

To prevent contamination of the environment with the organism in the culture Signup and view all the answers

What happens to microbial suspensions after use?

They are placed in a biohazard bag and autoclaved Signup and view all the answers

Why is it important to keep test tube caps and petri dish covers on media?

To reduce contamination of the media Signup and view all the answers

What is the definition of sterilization?

The process of killing or removal of ALL microorganisms in a material or on an object Signup and view all the answers

Why is it important to label test tubes and petri plates?

To keep track of the date, exercise number, and table number Signup and view all the answers

What is the term for the absence of microbial contamination?

Asepsis Signup and view all the answers

What is the purpose of flaming the wire loop after each streaking in the Streak Plate Method?

To sterilize the wire loop and prevent contamination Signup and view all the answers

What is the primary goal of the Streak Plate Method?

To separate individual cells and obtain a pure culture Signup and view all the answers

What is the term for a population of cells arising from a single cell?

Colony Signup and view all the answers

What is the purpose of using a sterile wire loop in the Streak Plate Method?

To inoculate the agar plate with bacteria Signup and view all the answers

What is the result of streaking the bacteria onto the agar plate in the Streak Plate Method?

Multiple colonies form, each derived from a single bacterial cell Signup and view all the answers

What is the importance of storing agar plates in a labelled plastic bag at 4 °C?

To prevent contamination and preserve the plates for future use Signup and view all the answers

Study Notes

Aseptic Technique and Sterilization

Aseptic technique is used to prevent microbial contamination in laboratory experiments
It involves preventing contamination of cultures with environmental microbes and preventing contamination of oneself or the environment with the organism in the culture
Sterilization is the process of killing or removing all microorganisms, including spores, from a material or object
There are no degrees of sterility; sterility means that there are no living organisms in or on a material

Preparation of Agar Plates

Agar plates must be labelled with name, name of organism, date, table number, exercise number, and other relevant details
Plates must be incubated upside down to reduce bacterial contamination and prevent water condensation from dropping onto the agar
Plates can be stored in labelled plastic bags at 4°C (refrigerator) for future use

Streak Plate Method

The streak plate method is used to obtain pure cultures of bacteria
A wire loop is used to pick up a small amount of bacteria and streak it onto the agar surface in four quadrants
The wire loop is flamed between each quadrant to prevent contamination
The goal is to separate individual bacterial cells and obtain isolated colonies in the later quadrants
Colonies are masses of offspring from an individual cell, also known as colony-forming units (CFU)

General Laboratory Practices

Inoculation loops must be heated in a flame and cooled before use to prevent contamination
Samples must not be dumped down the drain or in the trash can; they must be placed in biohazard bags and autoclaved
Test tubes and petri dishes must be labelled and kept upright to prevent leakage and contamination
Laboratory surfaces must be cleaned and disinfected regularly to prevent microbial growth

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Description

Learn about microbiology lab techniques such as the streak plate method, pour plate method, and spread plate method for obtaining pure cultures of bacteria.