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Agar, which is an extract of red marine algae, is preferred because only a few microbes can degrade the agar. It will remain as a solid during the growth of bacteria. It will stay as a liquid until cooled to 40 degrees Celsius. Once a solid, it will stay solid unless incubated at temperatures over 85 degrees Celsius.

Agar melts at 85 °C (358 K, 185 °F) and will solidify from 32-40 °C (305-313 K, 90-104 °F). Since many scientific applications require incubation at temperatures close to human body temperature (37 °C), agar is more appropriate than other solidifying agents that melt at this temperature, such as Gelatin.

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Elinor McDermott

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2y ago
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13y ago

"No living organism has yet been recorded as being able to metabolize (or eat/digest) agar, which is not true about Gelatin. Gelatin used to be the main solidifying agent until agar was found to be better (agar is a solidifying agent which is used in Asian cuisine because it is easily extracted from algae). "

This is incorrect. There are many agar digesting bacteria and fungi that have been found. Agar is preferable to gelatin for several reasons, it is a more consistent product with fewer impurities, less ethical concerns (animal hoofs versus algae) and is more effective as a solidifying agent than gelatin (0.7% agar is equivalent to 1.8% gelatin media)

the basic reason for the agar to be preferred over gelatin is much more technical than the above two reasons, agar is having a far more melting point than the gelatin.... it can melt over 60 degree Celsius but the gelatin on other hand takes much less temperature to melt and thus even gets liquefied at much lower temperatures like 37 to 40 degree Celsius.

the another reason also lies in the extraction procedures of the two mediums... gelatin is extracted from the bones of animals which makes it far more less accessible than the agar which can be extracted easily from the overgrowing algae called geledium....

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13y ago

Agar, which is an extract of red marine algae, is preferred because only a few microbes can degrade the agar. It will remain as a solid during the growth of bacteria. It will stay as a liquid until cooled to 40 degrees Celsius. Once a solid, it will stay solid unless incubated at temperatures over 85 degrees Celsius.

Agar melts at 85 °C (358 K, 185 °F) and will solidify from 32-40 °C (305-313 K, 90-104 °F). Since many scientific applications require incubation at temperatures close to human body temperature (37 °C), agar is more appropriate than other solidifying agents that melt at this temperature, such as gelatin.

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11y ago

Dr. Saxena says that agar is not hydrolyzed by most molecules, and agar doesn't liquidify till about >95'C. Once it has been solidified, and then it solidifies only at <50'C.

In contrast, Geletin liquidify at >28'C

and can be broken down by many organisms- pathogens.

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13y ago

Because of it's ability to absorb and retain large amounts of water.

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9y ago

Agar is used as a solidifying agent in culture media instead of gelatin because agar remains as a solid during growth of bacteria. Few microbes can degrade agar.

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14y ago

Because Agar is the solidification agent. Otherwise, the media would stay liquid !

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10y ago

agar remains as a solid during growth of bacteria and few microbes can degrade agar

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Q: Why is agar preferable to gelatin as a solidifying agent in culture media?
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What is the role of the agar ingredient in culture medium?

Agar is defined as a gelatinous substance obtained from various kinds of red seaweed and used in biological culture media. It is the culture medium.


What is broth culture?

The culture which contain an organism (bacterial colony) which you are required to grow in a broth media that is a media lacking solidifying agent agar. A pure culture should not contain other bacterial or fungal cells in it except the required or cultured one


Which is better for growing microbes a liquid culture or a semi solid culture?

Solid media is nutrient medium on whcih, when streak with the bacterial sample the bacterial colonies developed. It is commonly used to isolate different bacterial species or to have a pure culture i.e. a culture containing only one type of microorganism. At first R. Koch a German physician used to grow bacterial colony on boiled and sliced potatoes. Eventually he developed the culture media using meat extracts and protein digests and solidify it by using gelatin. Although gelatin is consumed by many bacterial species. Due to this disadvantage of gelatin Fannie Elishemius Hesse, the wife of Walther Hesse, one of the Koch's assistants suggest using AGAR as solidifying agent. Agar was not attacked by most bacteria and did not melt until reaching a temprature of 100oC. Furthermore once melt it did not solidify until it reached a temprature of 50oC.


Why the invention of solid culture media was of great important to the development of microbiology as a science?

Solid medium is media containing agar or some other, mostly inert solidifying agent. It has physical structure (broth lacks structure) and this allows bacteria togrow in physically informative or useful ways. Because bacteria could meetnutrient, air and light which they need easier; and it is more convenient forobservation and research.


Who invented agar in microbiology?

About a year later, in 1882, agar was first used as a solidifying agent. It had been discovered by a Japanese innkeeper, Minora Tarazaemon. The story goes that he threw out extra seaweed soup and discovered the next day that it had gelled during the cold winter night. Agar had been used by the East Indies Dutch to make jellies and jams. Fannie Eilshemius Hesse, the New Jersey -- born wife of Walther Hesse, one of Koch's assistants, had learned of agar from a Dutch acquaintance and suggested its use when she heard of the difficulties with gelatin. Agar -- solidified medium was an instant success and continues to be essential in all areas of microbiology.

Related questions

Can I use gelitan in a petri dish to grow samples?

Gelatin medium gives individual bacteria to produce seprate colonies, but despite this gelatin is not an ideal solidifying agent because it can be digested by many bacteria and melt at tempratures above 28oC.


What is the function of media agar?

Agar, which is a polysaccharide polymer, is a solidifying agent for culture medium. It also provides a solid surface for bacterial growth.


What is the function of agar in Potato dextrose agar?

solidifying agent.


Where does the solidifying agent agar come from?

Agar is made from seaweed.


Polysaccharide that acts as a solidifying agent in microbiological media?

agar


What is a broth culture?

The culture which contain an organism (bacterial colony) which you are required to grow in a broth media that is a media lacking solidifying agent agar. A pure culture should not contain other bacterial or fungal cells in it except the required or cultured one


What is a broth?

The culture which contain an organism (bacterial colony) which you are required to grow in a broth media that is a media lacking solidifying agent agar. A pure culture should not contain other bacterial or fungal cells in it except the required or cultured one


Is gelatin a salt?

No... Gelatin is a thickening/hardening agent created by boiling animal (bovine) bones.


What is the role of the agar ingredient in culture medium?

Agar is defined as a gelatinous substance obtained from various kinds of red seaweed and used in biological culture media. It is the culture medium.


How do the pure broth culture differ?

Pure broth culture is a liquid media, used to propagate large numbers of microorganisms. Where as Slant cultures are semi solid media containing a solidifying agent (usually agar). Can be used in determining bacterial motility and in promoting anaerobic growth.


Can you make gelatin out of fish?

No Gelatin is a thickening/hardening agent created by boiling animal (bovine) bones.


What are the materials used in Gelatin?

Gelatin is a thickening/hardening agent created by boiling animal (bovine) bones in water.