The document discusses several types of media used to culture and identify bacteria, including Endo agar, Eosin Methylene Blue agar, Hektoen Enteric agar, Macconkey agar, and Mannitol salt agar. Each type of media contains specific nutrients and indicators tailored to isolate and differentiate certain bacteria based on properties like lactose fermentation, production of hydrogen sulfide, or mannitol breakdown. The compositions and purposes of each media are outlined in detail.

1. MEDIA AND PRINCIPLE (PART -2)
Dr. S. SIVASANKARA NARAYANI

2. INTRO
• Endo agar
• Eosin Methylene Blue Agar
• Hektoen Enteric Agar
• Macconkey Agar
• Mannitol salt agar
15-09-2020Dr.SS - Media and Principle (Part -2)

3. ENDO AGAR
• Detect fecal contamination in water and dairy products
• Isolate and identify the presence of enteric lactose fermenters
(coliforms)
• Isolate and identify Salmonella typhi, a lactose nonfermenter
(noncoliforms)
Metallic sheen - E.coli E.coli(top),
Enterobacter
aerogenes (right lower
right), Shigella sonnet
(lower left)
15-09-2020Dr.SS - Media and Principle (Part -2)

4. ENDO AGAR
• Peptone - 10g
• Lactose - 10g
• Dipotassium phosphate – 3.5g
• Sodium sulfite – 2.5g
• Basic fuchsin – 0.5g
• Agar – 15g
• pH 7.5 +/- 0.2 at 25ºC
• Nitrogen, carbon, vitamins and minerals
• Fermentable carbohydrate
• Suppress gram positive bacteria
• Sodium sulfite + Basic fuchin
Red colour ( aldehyde reaction)
In addition fermentation of lactose
15-09-2020Dr.SS - Media and Principle (Part -2)

5. EOSIN METHYLENE BLUE AGAR
• Isolation of fecal coliforms
15-09-2020Dr.SS - Media and Principle (Part -2)

6. EOSIN METHYLENE BLUE AGAR
• Peptic digest of animal tissue – 10g
• Dipottassium phosphate – 2g
• Lactose – 5g
• Sucrose – 5g
• Eosin – Y – 0.4 g
• Methylene blue – 0.065g
• Agar – 13.5g
• pH -7.2 +/_ 0.2 at 25ºC
• Carbon , nitrogen and essential nutrients
• Fermentable carbohydrate
• Inhibit gram positive organism
• Under acidic condition – dark purple complex with green
metallic sheen
• Pink colour formation
15-09-2020Dr.SS - Media and Principle (Part -2)

7. HEKTOEN ENTERIC AGAR
Isolate and differentiate Salmonella and Shigella species
15-09-2020Dr.SS - Media and Principle (Part -2)

8. HEKTOEN ENTERIC AGAR
Protease peptone -12g
Yeast extract – 3g
Lactose – 12g
Sucrose – 2g
Salicin – 9g
Bile salts mixture – 9g
Sodium chloride – 5g
Sodium thiosulfate – 5g
Ferric ammonium citrate – 1.5g
Acid fuschin – 0.1g
Bromothymol blue -0.065g
Agar – 14g
pH -7.5 +/_ 0.2 at 25ºC
• Carbon, nitrogen and essential nutrients
• Organism ferment lactose, sucrose or salicin. Reduce
sulfur Hydrogen sulfide gas + Ferric ammonium
citrate black precipitate
• Inhibit gram positive cocci
• Source of sulfate
• Color indicators
15-09-2020Dr.SS - Media and Principle (Part -2)

9. MACCONKEY AGAR
Isolate and differentiate members of Enterobacteriaceae
Macconkey agar w/o crystal violet – detect gram positive
cocci
15-09-2020Dr.SS - Media and Principle (Part -2)

10. MACCONKEY AGAR
Peptone (Pancreatic digest of gelatin – 17.0g
Proteose peptone (meat and casein) – 3.0g
Lactose monohydrate – 10.0g
Bile salts – 1.5 g
Sodium chloride – 5.0g
Neutral red – 0.03g
Crystal violet – 0.001 g
Agar -13.5g
pH -7.1 +/_ 0.2 at 25ºC
• Carbon and energy sources
• Fermentable carbohydrate
• pH indicators
15-09-2020Dr.SS - Media and Principle (Part -2)

11. MANNITOL SALT AGAR
Isolation and differentiation of pathogenic Staphylococci
Especially Staphylococcus aureus
15-09-2020Dr.SS - Media and Principle (Part -2)

12. MANNITOL SALT AGAR
Pancreatic digest of casein – 5.0g
Peptic digest of animal tissue -5.0g
Beef extract – 1.0g
Sodium chloride - 75 g
D –Mannitol – 10g
Phenol red – 0.025 g
Agar – 15 g
pH 7.4 +/_ 0.2 at 25ºC
• Nitrogen, vitamins, minerals and amino acids essential for
growth
• Essential electrolytes for transport and osmotic balance
• Fermentable carbohydrate
• Indicator
• Organism ferment mannitol
Produce yellow colour colonies with halos
15-09-2020Dr.SS - Media and Principle (Part -2)

13. REFERENCE
• A photography Atlas for the microbiology laboratory, 4th edition – Michael. J. Leboffe, Burton E. Pierce
15-09-2020Dr.SS - Media and Principle (Part -2)

14. sivasan91@gmail.com
15-09-2020Dr.SS - Media and Principle (Part -2)

15. 15-09-2020Dr.SS - Media and Principle (Part -2)