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Food and Nutrition

Appendix G

Media Glossary
January 2006

Glossary of agars, broths and other reagents

Section G

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Gelatin Agar (GA)
Basal Medium
Peptone 4.0 g
Yeast extract 1.0 g
Gelatin 15.0 g
Agar 15.0 g
Distilled water 1.0 L
pH 7.2 ± 0.2  

Complete Medium:

Suspend basal ingredients in 1.0 L of distilled water, with constant stirring and boil to dissolve gelatin and agar. Autoclave 15 min at 121oC, cool to approximately 50oC and dispense.

Gelatin Phosphate Buffer (Gelatin Phosphate Diluent)
Basal Medium
Gelatin 2.0 g
Disodium hydrogen phosphate (Na2HPO4) 10.0 g
Distilled water 1.0 L
pH 6.2 ± 0.2  

Complete Medium:

Add ingredients to 800 mL of distilled water and dissolve by heating gently. Adjust pH to 6.2 with HCl. Add the remaining 200 mL of water (minus the volume of HCl used) and autoclave at 121oC for 20 min.

Gelatin Salt Agar (GSA)
Basal Medium
Sodium chloride (NaCl) 30.0 g
Gelatin 15.0 g
Peptone 4.0 g
Yeast extract 1.0 g
Agar 15.0 g
Distilled water 1.0 L
pH 7.2 ± 0.2  

Complete Medium:

Add components to 1 L distilled water. Mix thoroughly, gently heat with constant stirring to prevent scorching and bring to a boil. Dispense into tubes or flasks and autoclave at 121oC for 15 min. Pour into Petri dishes or leave in tubes.

Glycerol-peptone Medium
Basal Medium
Glycerol 25.0 mL
Peptone 1.0 g
Sodium chloride (NaCl) 0.5 g
Distilled water 75.0 mL
pH 7.0 ± 0.2  

Complete Medium:

Add ingredients to water, mix thoroughly and dispense 1-2 mL into screw-cap tubes. Autoclave 15 min at 121oC.

Note: For storage of cultures in freezer at -80oC (MFLP-46 Campylobacter species)

Gram Negative Broth (GN Broth or Hajna GN Broth)
Basal Medium
Tryptose 20.0 g
Dextrose 1.0 g
D-Mannitol 2.0 g
Sodium citrate 5.0 g
Sodium desoxycholate 0.5 g
Dipotassium phosphate (K2HPO4) 4.0 g
Monopotassium phosphate (KH2PO4) 1.5 g
Sodium chloride (NaCl) 5.0 g
Distilled water 1.0 L
pH 7.0 ± 0.2  

Complete Medium:

Dissolve ingredients in water. Autoclave at 121oC for 15 min. Avoid overheating.