Nutrient Media
This is a general purpose, non selective culture medium , which supply the essential nutrients such as carbon source , nitrogen , potassium salts etc which are required for the growth of microorganisms in laboratory conditions.
Types of Nutrients Media:
- Nutrient agar - its generally a culture medium which is solid in phase and contains the ingredients such as peptone(nitrogen source ), beef extract or yeast extract(vitamins , carbohydrates), distilled water, agar mixture (solidifying agent ).
- Nutrient broth -its a culture medium which is liquid in phase and contains ingredients such as peptone (nitrogen source),glucose(carbohydrate source), sodium chloride (maintainenace of osmotic balance), yeast extract (vitamins etc ) , distilled water , broth powder.
Method:
Sterilization -Before we prepare any media we need to sterilize all the laboratory equipments we need to use such as flasks , beakers , glass rod , needle , Petri dishes , micropipette tips , cotton using 70% ethanol to avoid chances of contamination.
wrapping- we need to wrap the equipments using newspaper or aluminium foil after all the equipments are washed , sterilised and dried properly and tie it using thread or rubber band .
autoclaving -first we need to let an autoclave create pressure for 5 minutes then keep the equipment wrapped in it properly set the pressure and wait for 30 mins until it reaches to 12rpm-15rpm then release the pressure and wait until it cools down it may take 4-5 hours of time and then it solidifies and later to melt it heat it on hot place while agitating continuously .
Pouring -
Laminar air flow-first preheat with uv light for 15 minutes to provide sterile environment, contamination free then switch it off and clean the surface using 70% ethanol and clean your hands too maintain silence then keep all the equipments inside then keep a spirit lamp fill it with 70% ethanol and then burn it using matchstick later keep the petridish in cross pattern near the flame(to avoid contamination) and pour the nutrient agar from the flask into the petridish remove other items from it and leave it to solidify .
streaking - later after it solidifies nutrient media is ready then streaking is done inside LAF near flame by opening petridish 45 °from side and using sterile inoculating loop first heat it until red hot then let it cool and do the streaking continuously by taking the bacteria you want to inoculate using micropipette .
Types of streaking methods:
1)Radiant streaking- The inoculum is spread at one edge of the plate, then streaked as vertical lines.
2)Quadrant streaking- The most common method, where the plate is divided into four equal sections (quadrants). The loop is sterilized between streaking each quadrant continuously.
3) T- streaking- The streaking pattern resembles the letter "T" on the agar plate.
4) Continuous streaking- method used to distribute inoculum evenly from edge of plate to centre while the movement is continuous and it even decreases the concentration of bacteria .
Spreading - later using the glass rod ( L- shaped ) spread the media with light hands across the Petri dish .
Your media is ready and now you can refrigerate it to avoid contamination.
In simple terms, nutrient media is the backbone of microbiology experiments, making it possible to grow, observe, and understand microorganisms in the lab
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