Because the peptone iron agar is used to detect ANAEROBIC bacteria. If you stab it deep into the agar you allow the bacteria to grow in the absence of oxygen. If you only inoculated the surface the bacteria wouldn't grow.
Inoculating an agar plate refers to transferring microorganisms onto the surface of the agar using a sterile inoculating loop. This allows the microorganisms to grow and form visible colonies that can be studied or identified.
Peptone ion agar is often used in biochemical tests to provide a source of nutrients for microbial growth. It contains peptone, which is a source of amino acids and peptides that promote the growth of bacteria. Peptone ion agar can support the growth of a wide range of microorganisms and is commonly used in tests such as the oxidase test or the indole test.
The process of applying a specimen to an agar plate to grow colonies is known as streaking. This technique involves using an inoculating loop to spread the specimen across the surface of the agar in a pattern that promotes the isolation of individual colonies for further study.
inoculation needle
Pancreatic digest of casein, papaic digest of soybean meal, beef extract, peptone
Peptone is the simplified source of protein and can be readily uptake by the microorganism. In nurtient agar it is the basic component/nutrient after which beef or yeast extract is used which are supplementary nutrients.
Malt extract agar typically consists of malt extract, agar as a solidifying agent, and may also contain additional nutrients like peptone or yeast extract. The exact composition can vary depending on the manufacturer or specific recipe used.
Beef extract for carbohydrates Peptone for protein and NaCl as salt
Stabbing into blood agar is used to assess the anaerobic growth of bacteria by inoculating the sample deep within the agar to create an oxygen gradient. This technique helps differentiate bacteria based on their ability to grow in low oxygen conditions.
Nutrient agar is a mixture of peptones, extracts, and agar, which are the sources of nutrients. Peptones provide nitrogen and amino acids, while extracts like beef or yeast extract provide vitamins and minerals. Agar acts as a solidifying agent for the growth medium.
Streaking is to produce single colonies. If we are digging to the agar while streaking the microbes, instead of growing on the agar surface grows in the subsurface as well. These colonies may be difficult to isolate.
This is important to prevent the inoculating needle from becoming stuck in the agar, taking out pieces of agar while trying to remove the instrument. This agar will get into the inoculum when sterilizing the needle on the flame, causing contamination to your sample.