Ohio Water Microbiology Lab
Research Topics
Internal Information
Ohio Water Science Center
USGS In Your State
USGS Water Science Centers are located in each state.
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Analytical Methods
The Ohio Water Microbiology Laboratory (OWML) provides
water-quality data on three major groups of microorganisms of public-health
significance in the United States— protozoa, bacteria, viruses.
- Protozoa are one-cell animals. They are the largest in
size and most complex and diverse among the three groups. The cells of
protozoa have true nuclei that contains DNA organized into chromosomes. They
range in size from 2 to 200 microns in diameter.
- Bacteria are simpler in structure and smaller than
protozoa. In bacteria, genetic information is encoded in a single molecule
of DNA that is in a free state within the cell. They range in size from 0.1
to 50 microns.
- Viruses are the smallest in size (0.02 to 0.3 microns)
and simplest in structure among the three groups and are not considered to
be living organisms; they are sometimes referred to “submicroscopic
particles” or “genetic elements.” They consist of DNA or RNA and a protein
coat. They must take over the machinery of a living cell to replicate.
Surface water, ground water, and sediments are collected and
analyzed for these microorganisms. For sample-collection methods, refer to the
USGS
National Field Manual. Special processing steps are used for sediments
before the analytical method is applied. See
sediment sampling and processing
methods in the methods section of a USGS
report.
Because pathogenic (disease-causing) microorganisms may appear intermittently
and in low concentrations and methods to detect pathogens are often costly and
time consuming, bacterial and viral indicator organisms are often used to assess
the microbiological quality of water. Indicator organisms are present in the
feces of warmblooded animals and provide information on the possible presence of
pathogens.
- Total coliforms, fecal coliforms, Escherichia coli (E.
coli), and enterococci are bacterial indicators.
- Coliphage are viral indicators.
Find out more about the analytical methods used by the OWML
for indicators and pathogens.
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U.S. Department of the Interior | U.S. Geological Survey
