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Culture Media - Bacteriological Grade Agar

     Why should someone who is using food grade agar to grow cultures switch to bacteriological grade agar?

     Take care when using food grade agar for bacteriological purposes. Many food grade agars are produced with gracilaria or gelidiella seaweed's and the gel strength of food grade agar that's produced is between 300 and 500 gms/cm2. What does that mean?

     The real problem is the gelling temperature of food grade agar, that is 40 - 44 Celsius. High quality bacteriological grade agar MUST be extracted from selected gelidium sesquipedalis seaweed's (not gracilaria or gelidiella seaweed's). This requirement gives bacteriological grade agar a gelling temperature of 34 - 35.5 Celsius.

     Agar is a colloidal substance, it is insoluble in cold water, but soluble in boiling water. When cooled to 34 - 43C, it forms a firm gel which does not melt again below 85C.

Our bacteriological grade agar has gel strength of 920 gms/cm2

Important Factors for Bacteriological Grade Agar
  • gel strength that must be over 800 gr/cm2
  • transparencies must be lower than 10 NTU but top qualities agar are even lower than 5 NTU
  • divalent captions that must not be higher than 1.000 PP

agar media for mushroom cultivation

The Certificate of Analysis for our Bacteriological Grade Agar, please Click Here

Bacteriological Grade Agar

BAC500: 500 Gram Bottle - $40.00
BAC250: 250 Gram Bottle - $24.95

For reference and recipies on how to use bacteriological grade base agar, please visit The Sporeworks for an easy and successful way to prepare this media.

Malt Extract Agar (MEA)

     Myco Supply offers a malt extract agar for mushroom tissue culture. A blend of high quality malt extract and cleanly processed base agar makes this an excellent mix for mycelium growth.


Malt Extract Agar

BAC500: 500 Gram Bottle - $30.95
BAC250: 250 Gram Bottle - $20.95
General Agar Information

    Agar is presently manufactured in many parts of the world with all modern extraction plants sharing a common process, although the precise details of the process vary from producer to producer. Extraction equipment is fairly standard in design, varying in material (cast iron, stainless steel) and size depending on desired products, age and production capacity of the plant. Agar is produced is a variety of countries ranging from Spain, Portugal, France, Morocco, Chile, Philippines, Japan, Korea, China, India, South Africa and Mexico. Myco Supply has contacted a large agar-agar manufacturer in response to the needs of our cultivators. We have negotiated a base price for a bacteriological grade agar, thus bringing you an excellent price for the markets best agar.

    Also, another very important aspect is that during extraction it is not possible to use any heavy bleaching and disinfectant agents that are normally used in food grade agar production to prevent contamination. If traces of these agents remains in the agar, evidently they will prevent bacterial and mycelia growth.

    Speaking of extraction, here is a little insight into why the harvesting and extraction process is so important in maintaining the quality of agar. The seaweed for extraction is typically harvested seasonally, depending on the location, growing environment, method of harvesting, and storm cycle. Current harvesting for Gelidium is of two types:

(a) Storm-cast weed is taken from the beaches and crudely sorted to exclude the more obvious non-agarophyte weeds, shells, stones, and man-made articles. The selected weed is, ideally, placed on large, raised platforms of open mesh wire and allowed to dry, but this practice is not always followed. The salt on the weed from seawater prevents overdrying during subsequent baling and storage. This is an important factor because storage may take place for one year or longer and the quality of the agar is adversely affected by overdrying and changes over time in storage. It is critical that drying commence very soon after the weed is removed from the water and that baling not take place until the drying process is complete. Much of the inherent variability in agar derived from beach drift seaweed results from local environmental conditions during and immediately after the storms which remove the seaweed from the bottom and cast it on to the beach. The duration of the storm, time on the beach, local weather (cloudy, rain, or sunny) will all impact on agar quality.

(b) Seaweed cut from beds by divers. This method yields high quality seaweed, ready for drying as described above. Considerably more costly, diver-collection is usually done by fisherman, during periods when fishing is not attractive. Advantages are that the seaweed can be harvested in a better condition and there are fewer attached, or unwanted, associated materials. Disadvantages include significant year-to-year variations in the quantity of seaweed, growing conditions, and over-harvesting which lead to a cyclical availability of the seaweed.

     Two main grades of agar account for the vast majority of agars produced and are recognized and distinguished by their particular properties and seaweeds of origin:

Type of Agar
Primary Seaweeds of Origin
Microbiological Agar
Gelidium and Pterocladia
Food-Grade Agar
Gracilaria (sugar-reactive agars) and Gelidium

     Most high-grade agar applications for microbiology and agarose require agars derived from Gelidium. Gelidium agars from different species and locales differ in their properties and not all Gelidium agars meet the specifications for microbiological or agarose applications. Lower grades of Gelidium agars are utilized in food applications. These microbiological and agarose agars are mostly Gelidium agars. Uses include: the preparation of culture media for bacteria, yeasts, and molds; plant and animal tissue culture; biotechnology; genetic engineering; DNA and protein separations; cloning of organisms; and the breeding of insects used in biological control. Other applications include its use in producing exact molds for manufacture of dental prostheses, reproducing sculptures and archeological pieces, reproducing fingerprints in police investigations and gelled electrolytes in the manufacture of leak-proof batteries. An estimated 100 mt, from the 10% noted above, is used in the production of agarose, a high-value, electrically neutral component of agar obtained through further refinement, which forms strong gels at low concentrations. Due to the special properties of agarose, it is utilized in DNA testing and provides an excellent medium for plant and animal cell cultures.

End User Market Segments
Base Agar - sold as a raw material selected microbiological agars Clinical-Industrial Microbiology Clinical laboratories, hospitals, research labs, industrial laboratories (quality control, process control etc.) Mycology, microbiology.
Selected agarose substitutes Biotechnology Various research organizations
Agarose - all low gel/low melt applications that require specific performance, e.g. gel electrophoresis, genomic separations, etc. Biotechnology Various research organizations. Gene therapy research
Plant tissue culture agars Agriculture Forestry and crops
Horticulture and crops
Extraction residue Agriculture Plant growth enhancers, Soil conditioners
Future R & D: Critical raw materials and chemical matrices Cosmetics Facial creams. Moisture regeneration (personal care)
Specialty agars Various New culture media, high and low temperature products.
Clarified gums Food, pharmaceutical, medicine cosmetics, life & food sciences Broad industry wide application

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Myco Supply
P.O. Box 15194
Pittsburgh, PA 15237

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