Indicator organism
Lua error in package.lua at line 80: module 'strict' not found. Indicator organisms are used as a proxy to monitor conditions in a particular environment, ecosystem, area, habitat, or consumer product. Certain bacteria, fungi and helminth eggs are being used for various purposes.
Contents
Types
Indicator bacteria
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The presence of coliform bacteria, such as E. coli, in surface water is a common indicator of faecal contamination. Coliform bacteria in water samples may be quantified using filter-based methods or 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), faecal contamination is suspected and confirmatory assays such as the Eijkman test are conducted.[citation needed]
Coliform bacteria selected as indicators of faecal 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 faecal organisms. Indicator organisms need not be pathogenic.[1]
Non-coliform bacteria, such as Streptococcus bovis and certain clostridia may also be used as an index of faecal contamination.[2]
Indicator fungi
Penicillium species, Aspergillus niger and Candida albicans are used in the pharmaceutical industry for microbial limit testing, bioburden assessment, method validation, antimicrobial challenge tests, and quality control testing.[3] When used in this capacity, Penicillium and A. niger are compendial mold indicator organisms.[3]
Molds such as Trichoderma, Exophiala, Stachybotrys, Aspergillus fumigatus, Aspergillus versicolor, Phialophora, Fusarium, Ulocladium and certain yeasts are used as indicators of indoor air quality.[4][5][6]
Indicator helminth eggs
Helminth eggs (or ova) are a good indicator organism to assess the safety of sanitation and wastewater reuse systems for resource recovery because they are the most environmentally resistant pathogens of all pathogens (viruses, bacteria, protozoa and helminths) and can in extreme cases survive for several years in soil.[7]
See also
References
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