R2A agar (Reasoner's 2A agar) is a culture medium developed to study bacteria which normally inhabit potable water. These bacteria tend to be slow-growing species and would quickly be suppressed by faster-growing species on a richer culture medium.
Since its development in 1979, it has been found to allow the culturing of many other bacteria that will not readily grow on fuller, complex organic media.
Typical composition (g/l)
- Proteose peptone, 0.5
- Casamino acids, 0.5
- Yeast extract, 0.5
- Dextrose, 0.5
- Soluble starch, 0.5
- Dipotassium phosphate, 0.3
- Magnesium sulfate per 7H2O, 0.05
- Sodium pyruvate, 0.3
- Agar, 15
Final pH 7 ± 0.2 @ 25 °C
- van der Linde K, Lim BT, Rondeel JM, Antonissen LP, de Jong GM (October 1999). "Improved bacteriological surveillance of haemodialysis fluids: a comparison between Tryptic soy agar and Reasoner's 2A media". Nephrol. Dial. Transplant. 14 (10): 2433–7. doi:10.1093/ndt/14.10.2433. PMID 10528669.
- Sandle, T. (July 2004). "An approach for the reporting of microbiological results from water systems". PDA J Pharm Sci Technol. 58 (4): 231–7.
- Reasoner DJ, Blannon JC, Geldreich EE (August 1979). "Rapid seven-hour fecal coliform test". Appl. Environ. Microbiol. 38 (2): 229–36. PMC . PMID 42349.