BIOL 111 Study Guide - Final Guide: Coliform Bacteria, Rainbow Trout, Water Pollution

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limecockroach99

25 Mar 2016

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Drinking water should not contain any colonies of coliform bacteria in 100 ml of water. Water used for swimming should have no more than 100-200 colonies in 100 ml of water. In streams, breakdown of wastes by bacteria depletes do and creates an oxygen sag curve. Factors that affect bio-degradation include flow rate, temperature, and water and ph levels. Salmon, trout, and steelhead all require good water quality with high oxygen content: pollution of freshwater lakes: Lakes contain stratified layers that undergo little vertical mixing and they have little flow. Water remains for about 1-100 years in lakes and for several days to weeks in streams. The great lakes contain at least 90% of the volume of fresh surface water in canada: pollution of groundwater: It can take thousands of years for contaminated groundwater to be bio-degraded of wastes. Underground tanks storing fuels are leaking their contents into groundwater in n. america.

Related Questions

Case Study:

Bacteria are everywhereâon our skin, in our food, suspended in our drinking water. Although the
microbial majority is benign, a few bacterial species can make us sick. To safeguard against food- and
water-borne disease, microbiologists routinely screen our drinking water for bacterial pathogens.
Animal feces contain coliform bacteria, microorganisms that inhabit the intestines of warm-blooded
animals. Many coliform bacteria are also found on plants and in soil and water. Coliform bacteria are
not pathogens themselves, but their presence indicates the possibility of finding pathogens. In contrast,
fecal coliform bacteria such as Escherichia coli are found in feces, and their presence in drinking water
indicates fecal contamination. E. coli can also be a pathogen itself, so if E. coli is found in drinking
water there is a good chance that other pathogens are present, too.1
To detect E. coli and other coliform bacteria, microbiologists filter water samples and place the filter in
a Petri dish containing growth medium such as Endo agar. Microorganisms from the water grow and
form colonies, giving an estimate of the number of bacteria in each milliliter of water.
While E. coli forms colored, shiny colonies on Endo agar, other coliforms grow as white or clear
colonies.

Dark colonies = E. coli
White/clear colonies = coliform bacteria
White + Dark colonies = total coliform
bacteria.

The guidelines of maximum allowable limits for total coliforms in drinking and recreational waters vary
by state. Representative limits appear in the table below.2, 3, 4

Table 1. Maximum allowable limits of fecal coliform bacteria
(cells/100 ml)

	Total Coliforms	E. Coli
Drinking Water	0	0
Recreational Waters	400	235

Questions
1. Why would we want to count the number of fecal coliforms in a water sample?
2. Do 400 coliforms per 100 milliliters strike you as very many?
3. How many other types of bacteria might be present in a normal water sample?
4. What problems might Mary encounter when she uses these techniques in Antarctica?

BIOL 111 Study Guide - Final Guide: Coliform Bacteria, Rainbow Trout, Water Pollution

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