Cultivation Of Microorganisms (Selective, Differential And Enriched Media,…
Cultivation Of Microorganisms
Routine Cultivation Media
Chemically Defined Media
Quantities of chemically pure, specific organic and inorganic compounds is known
Exact chemical composition of media is not known
Capable of supporting growth of most heterotrophs
Selective, Differential And Enriched Media
used to isolate (select) specific groups of bacteria
to distinguish among morphologically and biochemically related groups of organisms
media that has been supplemented with highly nutritious materials such as blood, serum, and yeast extract to grow fastidious organisms
Phenylethyl alcohol agar
used to isolate most gram positive organisms
Crystal violet agar
used for most gram negative microorganisms
7.5% Sodium chloride agar
most useful in the detection of members of the genus Staphylococcus and for halophilic (salt-loving) microorganisms
contains bile salts and crystal violet, which inhibits gram positive organisms and allows gram negative to grow.
Eosin-Methylene Blue Agar
partially inhibitory to the growth of gram-positive organisms, and thus gram-negative growth is more abundant.
Lactose, eosin dyes and methylene blue differentiate between enteric and lactose fermenters and nonfermenters and identification of the colon bacillus,
Mannitol Salt Agar
contains a high salt concentration, 7.5% NaCl which is inhibitory to the growth of most bacteria.
contains carbohydrate mannitol, which some staphylococci are capable of fermenting
phenol red, which is a pH indicator for detecting acid produced by mannitol-fermenting staphylococci
Allows demonstration of the hemolytic properties of certain microorganisms, such as streptococci.
No lysis of red blood cell results in no change of medium surrounding colonies
Incomplete lysis of red blood cells, results in greenish halo around bacterial growth
Lysis of red blood cells with complete destruction results in clear zone surrounding colonies
Streptolysin O: antigenic and oxygen labile enzyme
Streptolysin S: nonantigenic and oxygen-stable lysin