If there is more than one type of colony, each type should be streaked again on a separate plate to obtain a pure culture. Last updated on June 11th, Spread plate technique is a viable counting method employed to plate a liquid sample for the purpose of isolating or counting the bacteria present in that sample. A perfect spread plate technique […]. Last updated on June 11th, Pour plate method is usually the method of choice for counting the number of colony-forming bacteria present in a liquid specimen.
Because the sample is mixed with the molten […]. Last updated on June 17th, CLED cysteine-, lactose-, and electrolyte-deficient agar is a differential culture medium primarily used for isolation and enumeration of bacteria especially from urine samples. CLED is preferred over a combination of […]. News Ticker. Appropriate method to streak plate for isolation of bacteria. Contents 1 Principle of Streaking 1. Quadrant Streaking for isolation into pure culture.
Bi-plate streaking. Bacterial Culture Methods. About Acharya Tankeshwar Articles. Hello, thank you for visiting my blog. I am Tankeshwar Acharya. Blogging is my passion. I am working as an Asst. This technique involves using flame to kill contaminating organisms, and a general mode of operation that minimizes exposure of sterile media and equipment to contaminants.
When working with cultures of living organisms, it is extremely important to maintain the environments in which cells are cultured and manipulated as free of other organisms as possible. This means passing rims and lids through the flame produced by a Bunsen burner in order to kill microorganisms coming in contact with those surfaces. Sterile technique, in general, is a learned state-of-being, or mantra, where every utilization of any sterile material comes with the caveat of taking every precaution to ensure it remains as free of contaminants as possible for as long as possible.
A serial dilution is the step-wise dilution of a substance in solution. Usually the dilution factor at each step is constant, resulting in a geometric progression of the concentration in a logarithmic fashion. A ten-fold serial dilution could be 1 M, 0.
A culture of microbes can be diluted in the same fashion. For a ten-fold dilution on a 1 mL scale, vials are filled with microliters of water or media, and microliters of the stock microbial solution are serially transferred, with thorough mixing after every dilution step.
The dilution of microbes is very important to get to microbes diluted enough to count on a spread plate described later. 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. The streaking is done using a sterile tool, such as a cotton swab or commonly an inoculation loop.
This is dipped in an inoculum such as a broth or patient specimen containing many species of bacteria. The sample is spread across one quadrant of a petri dish containing a growth medium, usually an agar plate which has been sterilized in an autoclave.
Choice of which growth medium is used depends on which microorganism is being cultured, or selected for. Growth media are usually forms of agar, a gelatinous substance derived from seaweed.
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