umuC Test

Test organism

  • Salmonellae (Salmonella typhimurium)

Detectable effects (impact)

  • Activation of the SOS repair system of a cell (genotoxicity)

Test principle

  • The umuC test is based on a genetically modified strain of the bacterium Salmonella typhimurium.
  • A genotoxic substance induces the so-called umuC gene in the bacterial cell as part of the SOS repair system of the cell to counteract DNA damage. A reporter gene producing an enzyme (beta-Galactosidase) is coupled to this umuC gene. The enzyme converts a dye and thus induces a colour reaction that indicates the existence of genotoxic substances.

Test duration

  • 1.5 d (exposure time: 2 h)

Relevance

  • For the detection of DNA damage (genotoxicity)
  • Gentoxicity stands for any damage to the genetic apparatus, the genome. Genotoxic substances acting on the cell may cause chromosome breakage, the insertion or deletion of bases as well as DNA frameshifts. Most of such changes in the genetic substance are detected and repaired by the SOS repair system. These effects can be demonstrated with the umuC test.
  • Any unrepairable damage to the genetic substance will be passed on to the daughter cells during cell division. This is called mutagenity, the heritable, irreparable results of genotoxicity. These effects are demonstrated in the Ames test.

Guidelines and literature

  • International Standard Organisation (1996/2000) Water quality - Determination of the genotoxicity of water and waste water using the umu-test, EN ISO 13829 (2000) and 38415-3 (1996).
  • Escher BI, Bramaz N, Quayle P, Rutishauser S (2008). Monitoring of the ecotoxicological hazard potential by polar organic micropollutants in sewage treatment plants and surface waters using a mode-of-action based test battery, J. Environ. Monit. 10, 622-631.