What is streaking for isolation

Note that the agar surface faces downward, thereby minimizing contamination from the air. Figure A Pattern for isolation streaking section 1 of a plate.

Figure A Illustration of isolation streak technique section 1 to section 2. Figure A An example of growth hours after isolation streaking a plate to obtain isolated colonies.

Protocol for Streaking for Isolation Nutrient agar plates can be streaked using a three-phase or a four phase pattern Figure A YouTube Demo [1] The handling of the plate can be accomplished in a number of ways, all of which attempt to minimize possible contamination by either keeping the lid over the plate or by keeping the plate upside down Figure A Isolation streak technique: from broth, slant, or plate to plate.

If using a loop, sterilize it in a bunsen burner flame and allow the loop to cool for a few seconds. Not allowing any cap, lid, or plug to leave your hand, dip your loop in the donor broth culture or touch your loop to a pure colony of bacteria on a streak plate. If using a broth and a sterile cotton swab, remove the sterile cotton swab from its container; be sure not to touch the swab to anything.

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. Last updated on June 21st, Microorganisms can produce different types of volatile compounds that may give characteristics smell, pleasant scent, or pungent odor. Production of these volatile chemicals depends on the metabolic characteristics of […].

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.