MICROBIOLOGICAL MEDIA

 

Web Links

Techniques-

Streak Plate -  http://www2.austin.cc.tx.us/microbugz/18streakiso.html

Illustration of streaking technique for transfer of bacteria to a plate and isolation of the bacteria on the plate

http://www.arches.uga.edu/~allerix/rachel.html

Transfer of microorganisms to broth and slant tubes

http://www.rlc.dcccd.edu/MATHSCI/reynolds/MICRO/lab_manual/transfers.html

Staining -

Gram Stain - http://www2.austin.cc.tx.us/microbugz/12gramstain.html

Simple Stain- Methylene Blue - http://www2.austin.cc.tx.us/microbugz/10simplestain.html

Capsule Stain- http://www2.austin.cc.tx.us/microbugz/14capsule.html

 

Selective and Differential Media

 Brilliant Green Agar -         http://www.staffs.ac.uk/schools/sciences/biology/dr/bgreenagar.html

Eosin Methylene Blue Agar - http://www.jlindquist.net/generalmicro/dfemb.html

MacConkey Agar -               http://www2.austin.cc.tx.us/microbugz/24mac.html

TSI - http://medic.med.uth.tmc.edu/path/triple.htm

Blood Agar- http://www2.austin.cc.tx.us/microbugz/19blood.html

Mannitol Salt Agar - http://www2.austin.cc.tx.us/microbugz/20msa.html

TSA - Trypticase Soy Agar -  http://www.talron.co.il/products/prod46.htm

 

Specialized Biochemical Media and Tests

Casein hydrolysis - http://homepages.wmich.edu/~rossbach/bios312/LabProcedures/Casein%20hydrolysis%20test%20results.html

Gelatin liquefaction - http://www2.austin.cc.tx.us/microbugz/38nutgel.html

Starch hydrolysis test - http://www2.austin.cc.tx.us/microbugz/40starch.html

Tributyrin hydrolysis - http://www.rlc.dcccd.edu/MATHSCI/reynolds/MICRO/lab_manual/lipid.html

TSI - http://vtpb-www.cvm.tamu.edu/vtpb/vet_micro/bacteriology/tsi/default.html

Urease - http://medic.med.uth.tmc.edu/path/urease.htm

Indole Test - http://medic.med.uth.tmc.edu/path/indole.htm

Oxidase Test - http://medic.med.uth.tmc.edu/path/oxidase.htm

Motility test - http://www.staffs.ac.uk/schools/sciences/biology/dr/motilitytest.html

http://www2.austin.cc.tx.us/microbugz/17bmotility.html

 

Citrate - http://www2.austin.cc.tx.us/microbugz/31citrate.html

http://www.vet.uga.edu/erc/WEBFILES/ignrenci.html

 

Differential - Has a consituent that causes an observable color change in the media or a pH change that affects the media

Selective- Selective media encourages the growth of some organisms but supresses the growth of other organsims

Many media are both selective and differential

Media Picture Organisms Identified Selective/Differential
Brilliant Green Agar  

 

 

 Salmonella species Brilliant green dye inhibits Gram +

Gram - differntiated

Shigella and Salmonella

Shigella colonies red to white

Salmonella= yellow to green
Eosine Methylene Blue ( EMB)

 

Gram - enteric pathogens Moderately inhibits Gram + organisms

E. coli colonies are purple and have a metallic sheen

Enterobacter is pink because it ferments lactose

Other Gram- are light pink because they are non fermenters
MacConkey

Gram - Enteric pathogens Crystal violet and bile salts inhibit the growth of Gram + bacteria

Lactose and the pH indicator neutral red turn red when sugar is fermented
Triple Sugar Iron

 

 

 

 

 

Used with slants to test aerobic and aerobic action of bacteria - fermentation of sugar and generation of gas enteric pathogens produce red slant and yellow butt with no gas
Blood

 

 

 

 

                     

Used to differentiate between streptococcus species and staphylococcus Exhibit hemolysis

alpha - green

beta - clear

gamma - no hemolysis
MSA

Mannitol Salt Agar

 

 

 

Used to identify staphylococcus aureus mannitol fermenter - color change from pink to yellow

grow in media - staphylococcus
 

 

TSA

 

 

 

Tryptic Soy Agar Formula Per Liter

Tryptone . . (.Pancreatic Digest of Casein ) 15 g
Soytone . . . (.Papaic Digest of Soybean Meal . .) 5 g
Sodium Chloride 5 g
 Agar 15 g

Final pH 7.3 ± 0.2 at 25°C

 

 Used in the differentiation of haemophilus species Supplemented with salt for the identificaton of halophilic species
 

 

 

PEA

Selective for Gram + and Inhibits the Growth of Gram - Gram - do not grow as well or at all
 

 

Starch Agar

 

 

Show whether bacterium has enzyme to break down starch when stained with Iodine