Indicator organism

Indicator organism

Indicator organisms are used to measure potential fecal contamination of environmental samples. The presence of coliform bacteria, such as "E. coli", in surface water is a common indicator of fecal contamination. Coliform bacteria in water samples may be quantified using the most probable number (MPN) method, a probabilistic test which assumes cultivable bacteria meet certain growth and biochemical criteria. If preliminary tests suggest that coliform bacteria are present at numbers in excess of an established cut-off (the Coliform Index), fecal contamination is suspected and confirmatory assays such as the Eijckman test are conducted.Fact|date=December 2007

Coliform bacteria selected as indicators of fecal contamination must not persist in the environment for long periods of time following efflux from the intestine, and their presence must be closely correlated with contamination by other fecal organisms. Indicator organisms need not be pathogenic. [cite web |url=http://www.des.state.nh.us/factsheets/wwt/web-18.htm |title=Fecal Coliform as an Indicator Organism |accessdate=2007-11-30 |last= |first= |coauthors= |date=2003 |work=Wastewater treatment environmental fact sheet |publisher=New Hampshire Department of Environmental Services]

Non-coliform bacteria, such as "Streptococcus bovis" and certain clostridia may also be used as an index of fecal contamination. [cite book |last=Gerardi |first=Michael H. |authorlink= |coauthors=Mel C. Zimmerman |editor=Michael H. Gerardi |title=Wastewater Pathogens |url= |edition= |series=Wastewater Microbiology Series |date= |year=2005 |month=January |publisher=John Wiley & Sons, Inc. |location=Hoboken, NJ |isbn=9780471206927 |pages=p. 147 ]

ee also

*Coliform bacteria
*Coliform Index
*E. coli

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • indicator organism — An organism whose presence indicates the condition of a substance or environment, for example, the potential presence of pathogens. Coliforms are used as indicators of fecal pollution …   Dictionary of microbiology

  • Indicator bacteria — Each gram of human feces contains approximately 12 billion (12*109) bacteria, among them may include pathogenic bacteria, such as Salmonella , associated with gastroenteritis. In addition, feces may contain pathogenic viruses, protozoa and… …   Wikipedia

  • indicator — noun Date: 1666 1. one that indicates: as a. an index hand (as on a dial) ; pointer b. (1) gauge 2b, dial 4a (2) an instrument for automatically making a diagram that indicates the pressure in and volume of the working fluid of an engine… …   New Collegiate Dictionary

  • indicator species — ▪ ecology       organism often a microorganism or a plant that serves as a measure of the environmental conditions that exist in a given locale. For example, greasewood indicates saline soil; mosses (moss) often indicate acid soil. Tubifex worms… …   Universalium

  • Model organism — Escherichia coli is a gram negative prokaryotic model organism …   Wikipedia

  • Bacteriological water analysis — is a method of analysing water to estimate the numbers of bacteria present and, if needed, to find out what sort of bacteria they are. It is microbiological analytical procedure which uses samples of water and from these samples determines the… …   Wikipedia

  • Reclaimed water — Reclaimed water, sometimes called recycled water, is former wastewater (sewage) that has been treated to remove solids and certain impurities, and then allowed to recharge the aquifer rather than being discharged to surface water. This recharging …   Wikipedia

  • Silver nitrate — Silver nitrate …   Wikipedia

  • Coliform Index — The Coliform Index is a rating of the purity of water based on a count of fecal bacteria. Coliform bacteria are microorganisms that primarily originate in the intestines of warm blooded animals. By testing for coliforms, especially the well known …   Wikipedia

  • Columbia Slough — Coordinates: 45°38′36″N 122°46′07″W / 45.64333°N 122.76861°W / 45.64333; 122.76861 …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”