- · Is also called Reasoner’s 2A Agar.
- · Non-selective medium.
- · Detect hetero tropic and obligated bacteria.
- · These bacteria tend to be slow growing species.
- · Developed to study bacteria which normally inhibit potable water.
- · R2A agar was developed by “Reasoner and Geldreich” for bacterial plate counts of treated water.
- · R2A agar low nutrient medium and lower incubation temperature and higher incubation time. Growth of stressed and chlorine-tolerant bacteria.
- · R2A is recommended in standard methods for pour plate, spread plate and membrane filtration method (MFM) for hetero tropic plate counts.
- · These bacteria tend to be slow-growing species and would quickly be suppressed by faster- growing species on a richer culture medium.
Composition
Grams/liters
Enzymatic Digest of Casein
-------------------------------------------
0.25g
Enzymatic Digest of Animal
tissue(proteose peptone) ---------- 0.25g
Acid Hydrolysate of
casein---------------------------------------------0.5g
Yeast
Extract--------------------------------------------------------------0.5g
Dextrose
(Glucose)--------------------------------------------------------0.5g
Soluble
Starch-----------------------------------------------------------0.5g
Dipotasium
phosphate-----------------------------------------------0.3g
Megnesium sulfate
Heptahydrate---------------------------------0.05g
Sodium Pyruvate---------------------------------------------------0.3g
Agar----------------------------------------------------------------------15g
pH= 7.2±0.2 at 250C
- · Enymatic digest of Casein and Animal tissue(proteose peptone) and Acid hydrolysate of casien – source of Nitrogen and Carbon
- · Yeast extract – source of vitamins
- · Dextose (glucose)--- sucrose of carbohydrates
- · Soluble Starch aids in the recovery of injured organism ( absorbing toxic metabolic by product).
- · Dipotasium Phosphate --- pH balance
- · Megnium sulfate heptahydrate ----- source of divalent cations and sulfate.
- · Sodium Pyruvate ---- increase the recovery of stressed cells (chlorine –tolerant Bacteria)
- · Agar--- solidification agent.
