How is starch agar made?
Starch agar consists of heat-stable digestive products of proteins (called peptones), as would be found in nutrient agar. These provide amino acids, minerals, and other nutrients used by a wide variety of bacteria for growth. In addition, the medium contains soluble starch.
What are the ingredients of starch agar media?
Peptone, yeast extract and HM peptone B extract provide nitrogenous compounds, carbon, sulphur, trace elements etc. to the microorganisms. Sodium chloride maintains osmotic equilibrium. Flood the surface of 48 hours old culture on Starch Agar with Grams Iodine (S013).
How is agar media prepared?
Preparation of Nutrient Agar
- Suspend 28 g of nutrient agar powder in 1 litre of distilled water.
- Heat this mixture while stirring to fully dissolve all components.
- Autoclave the dissolved mixture at 121 degrees Celsius for 15 minutes.
- Once the nutrient agar has been autoclaved, allow it to cool but not solidify.
Why is starch added to media?
Starch molecules are too large to enter the bacterial cell, so some bacteria secrete exoenzymes to degrade starch into subunits that can then be utilized by the organism. Starch agar is a simple nutritive medium with starch added. Iodine has been added to this starch agar plate.
How do you test for starch in agar?
In starch hydrolysis test (also known as amylase test), we use starch agar, which is a differential nutritive medium. The test organisms are inoculated onto a starch plate and incubated at 30°C until growth is seen (i.e. up to 48 hours). The Petri plate is then flooded with an iodine solution.
What are the products formed when starch is hydrolyzed?
THE complete hydrolysis of starch yields the sugar d-glucose, or, as it is commonly known, dextrose. The hydrolysis is sup- posed to proceed by steps, various intermediate products being formed. These have often been enumerated as soluble starch, maltose and various dextrins.
How do you sterilize media?
Agar-free media will usually dissolve on gentle agitation. Media containing agar should be heated to dissolve the agar before autoclaving. Bring the medium to the boil without scorching or burning. Most culture media will require final sterilization in an autoclave at 121°C for 20 minutes.
How is agar calculated?
According to the manufacturers instruction for nutrient agar (NA), 28 g of NA = 1000 ml (1 Liter) of distilled water. This implies that, 28 g of NA should be dissolved in 1000 ml of distilled water; and this is usually for 50 plates of NA.
What type of media is starch agar?
Starch agar is a differential medium that tests the ability of an organism to produce the extracellular enzymes (exoenzymes) α-amylase and oligo- 1,6-glucosidase that are secreted out of the bacteria and diffuse into the starch agar.
How do you prepare starch casein agar?
Preparation of Starch Casein Agar Suspend 63.0 grams of Starch Casein Agar in 1000 ml distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Mix well and pour into sterile Petri plates.
What is the use of seawater in agar agar?
The salts of seawater provides complex ionic sources that makes the medium suitable for marine microbial flora and also buffers the medium. It is used for the detection of saccharolytic marine bacteria. It is used for the isolation of actinomycetes. Suspend 63.0 grams of Starch Casein Agar in 1000 ml distilled water.
How do you make actinomycetes from casein agar?
Suspend 63.0 grams of Starch Casein Agar in 1000 ml distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Mix well and pour into sterile Petri plates. Actinomycetes: Off-white to yellow colored homogeneous free flowing powder.
What is casein Agar made of?
Starch Casein agar is made with various nutrients which allow the growth of a wide variety of microorganisms that do not usually don’t grow on a primary medium like Nutrient agar as they require specific nutrients or supplements. The primary constituents of the media are starch, casein, and seawater.