5 pages/≈1375 words
Microorganisms and Bacteria: Aseptic Technique, Streak Plate Method (Lab Report Sample)
Microorganisms and Bacteria
1 Aseptic Technique
Aseptic technique is a set of specific laboratory practices that are always performed before beginning experiments. The specific practices are meant to maintain as well as maximize the control and eradication of pathogens in the laboratory set up. They are always carried out under strict sterile conditions to either reduce or eliminate pathogenic contamination in the laboratory working areas. The aseptic technique achieves greater control or eradication of microbial contamination than other practices that focus on sanitization of microorganisms. In order to ensure complete control of pathogenic microorganisms, it is critical to follow the aseptic technique requirements to the letter. There are fundamental practices that should always start before carrying out any form of experiment. These practices include:
* Cleaning the laboratory working bench: The laboratory working bench should be cleaned thoroughly using either absolute ethanol or 70% ethanol. This ensures that any microorganism present is inactivated before a scientist begins an experiment.
* Flaming loops: This aseptic technique is done to inactivate any microorganisms that might be present on loops and straight wires, and that might interfere with a new experiment. Usually, loops and straight wires are introduced into a Bunsen burner flame for a few minutes until red hot. When the loops and wires glow red hot, this confirms that any unwanted microorganism is inactivated.
* Inoculation of agar slants: When introducing microorganisms' cultures on agar slants or any other form of agar, wire loops should be used to inoculate. Caution, however, should be exercised in order to avoid breaking the solid agar. Inoculation should specifically be carried out in a zigzag manner.
2 Streak Plate Method
In the Streak Plate procedure, it is important to use a loop (either a nickel-chromium wire or disposable plastic) to transfer an inoculum onto a differential medium. Using the loops is among the critical practices required in the aseptic technique because they reduce the risk of contamination and also infection. It is also easier to sanitize the loops (wires and plastics) than it is with other materials.
The Streaking Plate procedure is carried out in a laminar flow hood in an aseptic technique as follows:
* Labeling petri dishes: The procedure begins with labeling of petri dishes to be used in inoculation. Usually, petri dishes are labeled on the bottom close to the edge of the bottom of the dish; this is done to reserve some space for observation after the dish has been incubated together with the inoculum. Labels must bear the inoculum name, the type of agar used, the date, and name or initials of the plater. If any water is observed on the agar, it should be removed using a sterile cotton swab.
* Sterilization of Loops: Even before obtaining a specimen of the inoculum, the transfer wire loops should be sterilized by using a Bunsen burner. The flame of the burner should heat the loop until it is red hot; this confirms inactivation of any microorganisms that might be present on the loop prior to beginning an experiment. The loop is then allowed to cool slowly usually by holding it in the air. After the loop has cooled, it can be used to transfer the inoculum onto the petri dish containing the agar. It is recommended that a new loop be used (in case of plastic loops) or be sterilized (in case of wire loops) when streaking each new sector on the petri dish.
* Streaking the Plate: When inoculating the agar, the lid of the petri dish is removed. The streaking process should be shorter to minimize exposure of agar to air. The first streak is applied on one area of the dish. By touching the loop on the agar, the inoculums on the loop are transferred onto...
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