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.
What is the purpose of streaking a plate with bacteria?
In microbiology, streaking is a technique used to isolate a pure strain from a single species of microorganism, often bacteria. Samples can then be taken from the resulting colonies and a microbiological culture can be grown on a new plate so that the organism can be identified, studied, or tested.
What material is a streak plate?
The surface across which the mineral is dragged is called a “streak plate”, and is generally made of unglazed porcelain tile. In the absence of a streak plate, the unglazed underside of a porcelain bowl or vase or the back of a glazed tile will work.
How would you know if the streak plate is contaminated?
Fungal contamination will appear as fuzzy, filamentous, or hair-like growths, and should be visible to the unaided eye. Fungal contamination often occurs right along the edge of an agar plate. If the plate has not been inoculated, the presence of any bacterial colonies indicates contamination.
What could be a possible explanation for what went wrong on the streak plate below?
Obtaining a culture sample before streaking every quadrant. What could be a possible explanation for what went wrong on the streak plate above? The quadrants are not properly spaced & The loop was not sterilized between quadrants. When using the streak plate technique how often is it necessary to sterilize your loop?
What is the objective of streaking microbial cultures over a broad agar surface?
The objective of this technique is to dilute the culture, and to produce well-isolated colonies from a concentrated mass or suspension of cells. Streaking over a broad agar surface provides a technique by which mixed cultures can be separated since colonies of different types can usually be isolated by this means.
Which lab instrument is used to make a streak plate?
From top to bottom, shown are toothpicks (flattened not round), a wire loop, a disposable plastic loop, and wooden sticks. Toothpicks are typically transferred to a small glass beaker with the wide end down then covered with foil when autoclaved to sterilize prior to use.
What is streak plating method?
Streak plate technique is used for the isolation into a pure culture of the organisms (mostly bacteria), from a mixed population. The inoculum is streaked over the agar surface in such a way that it “thins out” the bacteria. Some individual bacterial cells are separated and well-spaced from each other.
What is a ceramic streak plate?
The “streak test” is a method used to determine the color of a mineral in powdered form. The streak test is done by scraping a specimen of the mineral across a piece of unglazed porcelain known as a “streak plate.” This can produce a small amount of powdered mineral on the surface of the plate.
How does the streak plate technique work in bacteria?
Quadrant Streaking showing the colonies thinning as the streaking moves clockwise. Streak plate technique is used for the isolation into pure culture of the organisms (mostly bacteria), from mixed population. The inoculum is streaked over the agar surface in such a way that it “thins out” the bacteria.
How are pure cultures obtained from streak plates?
Pure cultures can be obtained by picking well isolated colonies and re-streaking these on fresh agar plates. Common assumption is an isolated colony of bacteria is the progeny of a single bacterial cell (i.e. colony is the clone).
What do you see when you streak a bacterial culture?
You should see bacterial cells growing along the streaks and in isolated areas. When sterilizing the inoculating loop, make sure that the entire loop turns orange before using on the agar plates. When streaking the agar with the loop, be sure to keep the loop horizontal and only streak the surface of the agar.
How do you get rid of bacteria in a culture plate?
Remove the lid from a culture plate containing the desired microorganism. Cool the inoculating loop by stabbing it into the agar in a spot that does not contain a bacterial colony. Pick a colony and scrape off a little of the bacteria using the loop.