The response at the individual level is usually linked to a
defined type of pollution stress. In contrast, a multi-population
examination is slightly more difficult to understand, since it
requires more exhaustive testing due to the complexity of
additional sources of disturbance [8].
Because of their attributes, bacteria can be considered good
potential bioindicators at different organizational levels. Bacteria
are ubiquitous and can be assayed at low cost; in addition,
they have the highest surface-area-to-volume ratio compared
to other organisms. Furthermore, due to the high number of
individuals at each microsite, analysis of bacterial communities
in terms of an increase or decrease in taxon provides
robust results. As a result, the assessment level of pollution
within an environmental sample is commonly achieved by
analyzing single bacterial species or a limited bacterial population.
For example, it is well known that the metabolic
pathway of Vibrio fischeri's bioluminescence is useful in
detecting xenobiotic pollutants, while fecal bacteria (coliforms
and enterococci) are regularly used to measure fecal pollution
levels [9,5]. In contrast, use of an entire bacterial community
as a bioindicator in freshwater environments has been limited