Question

Write about the Procedures of streaking on primary growth medium in general.what is the purpose?how does help the medical microbiologists identify strains of microorganisms

Answer 1

The main goal and purpose of streaking is isolation, the streking method is used to produce isolated colonies of a particular organism on an agar plate. The streaking method is adopted to study the colony morphology of an organism, it's also helpfull to separate organisms in a mixed culture, the most commonly used organism could be a bacteria.

To perform the method of streaking a source of bacteria which could be an previously streaked agar plate or an stock culture is necessary, other materials includes an inoculation loop, bunsen burner, lighter, and petri dish with agar.

The commonly used streaking methods includes namely, T-Streak method or three quadrant method and four quadrant method

The process starts with sterilizing the inoculation loop using the bunsen burner by passing it through flame, before moving the loop to any quarter of agar this sterilizing process to be done on loop and allow the loop to cool followed by which its dipped in to inoculum present in the tube or culture bottle and then streak the inoculating loop very gently over a quarter of the plate back and forth in a zigzag motion, if following T-Streak method the agar plate is divided in to three quarters and for four quadrant method four quarters which can be drawn to back side of agar plate as needed, flame the loop again and allow it to cool now extend the streak in to the second quarter of plate from the first quarter that was streaked already and follow the same process to streak to third and fourth quarter from the second and third respectively.

This will help in diluting a large concentration of bacteria to a smaller concentration which in turn grows in to a quantity of cells or isolated colonies, to allow the bacteria to reproduce the agar plate is incubated at 37°C for 24 to 36 hours depending on the strain used.

Based on the morphology single bacteria can be identified from the resultant mixed colonies, to yield a pure culture for further analysis this can be sub cultured to new media plate.

Bacteria occur in mixed populations, the human body do have millions of bacteria which fight against the invading pathogens. It is important that the bacteria be divided from the other species to able to study about the morphology of individual species. It's necessarily important in determining a bacterium in clinical sample to identify the causative agent of a bacterial disease, when the bacteria is streaked and isolated, this can be done.