An A1 broth is a liquid culture medium used in microbiology for the detection of fecal coliforms in foods, treated wastewater and seawater bays using the most probable number (MPN) method. It is prepared according to the formulation of Andrews and Presnell given below.[1] It is used with a Durham tube, a positive tube being one that exhibits a trapped bubble of gas.

Typical formula (g/L)

Tryptone20.0
Lactose5.0
Sodium chloride5.0
Triton X-1001.0
Salicin0.5

[2]

Directions

Suspend the dry ingredients in one liter of cold distilled water. Gently heat until completely dissolved and distribute 9 mL into test tubes with an inverted Durham tube. Sterilize in an autoclave at 121°C for 15 minutes. If needed, prepare multi-strength broth weighing the appropriate quantity of the dry medium. The final pH is 6.9 ± 0.1.[3]

Widespread usage

Variants of this test has been used for potable water across the globe, for example by the Cree community of Split Lake, Manitoba, by the Mapuche people of Maquehue, Chile[4] and in Singapore, Malaysia and Thailand [5]

References

  1. ↑ "Transdifferentiation of Stem Cells – Page 1174245593 – Experimental Biology". Archived from the original on September 14, 2007.
  2. ↑ "17112 A1 Broth BioChemika, for microbiology".
  3. ↑ "A1 Broth |Sisco Research Laboratories (SRL) (India)". www.srlchem.com.
  4. ↑ "Portable Water-testing Kit: International Development Research Centre". Archived from the original on December 4, 2007.
  5. ↑ Suan, Sim Tiow; Chuen, Ho Yueh; Sivaborvorn, Komol (September 9, 1988). "Southeast Asian experiences with the coliphage test". Toxicity Assessment. 3 (5): 551–564. doi:10.1002/tox.2540030510. Archived from the original on 2012-12-16. Retrieved 2020-09-09 – via Wiley Online Library.


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