Download Abstract Microbial source tracking (MST) is a powerful emerging

Application of Microbial Source Tracking Methods to Food Safety
and Protection of Water Resources
Charles
1Department
1
Hagedorn
and Susan
2
Allender-Hagedorn
of Crop and Soil Environmental Sciences, 2Department of English and founding editor, Environmental Detection News and
The Journal of Environmental Detection
Abstract
Microbial source tracking (MST) is a
powerful emerging technology that identifies
sources of fecal pollution in impaired waters.
Four different approaches to MST
methods are currently being developed. The
first uses a database or “library” of known
sources of fecal bacteria (i.e., humans,
livestock, companion animals, wildlife, etc.)
that are “fingerprinted” by a variety of
biochemical or molecular protocols. Fecal
bacteria of unknown source (isolated from
polluted waters) are compared against the
library to look for fingerprint. To date this has
been the most widely used approach.
The second uses DNA sequences in fecal
organisms that are unique to specific sources.
At this time, only a few useful source-specific
sequences have been found, but this approach
probably represents the future of MST as
libraries, and in some cases cultivation of the
fecal organisms, are not needed.
The third involves detection of chemicals
that are unique to human-origin pollution, such
as optical brighteners in detergents and
caffeine from beverages. This approach has
been successfully deployed, especially in
urban settings.
The fourth approach uses DNA sequences
or serum immunoglobins from specific
sources rather than from fecal organisms
within those sources. This is a new approach
that has not been thoroughly tested.
Currently a great deal of attention is
focused on the problem of guarding the safety
of the nation’s waters food supply from both
accidental and deliberate threats. But the very
recognition of a threat can only be made by
comparison of that potential threat with a
baseline of “normal” conditions. MST is a
technology that can be utilized both for
creation of that baseline and for analysis of
changes from the baseline. This poster
analyzes how the lessons learned in the
development of MST can be applied to
problems faced identifying sources and/or
remediation of threats to food and water safety.
Library Fingerprinting of
Target Organisms*
Antibiotic/biochemical patterns
Ribotyping and/or repetitive PCR
Fecal DNA Sequencing
(non-library
methodology)
Chemical Detection
(non-microbial)
Denaturing gradient gel
electrophoresis
Toxin biomarkers
Optical brightenersdetergents
Reverse transcriptase PCR
Fecal sterols and stanols
Pulse field gel electrophoresis
Length heterogeneity PCR
Caffeine
Amplified fragment length
polymorphism
Terminal restriction fragment
length polymorphism
Cosmetic and drug
residues
Source DNA Sequencing*
(non-microbial)
Source-specific DNA
Source-specific immunoglobulins
*humans, dogs, cattle, deer,
waterfowl, etc.
*bacteria, viruses, protozoa
Problems of Detection In Food Safety and Water Resource Protection
 Source tracking is an emerging field and all methods are still under development and need improvement. It is not yet clear
which methods and approaches will best serve the needs of other scientific disciplines.
 Selected methods and target organisms will need to be evaluated for accuracy, specificity, and geographical and temporal
stability when deployed by different communities for purposes other than water quality.
 Criteria for determining reliability, management relevance, and cost and logistics will have to be developed as source
technology is transferred to new environments and is expected to measure different things.
 Once the issues with technology transfer have been accommodated, baselines, similar to those used in water quality, will
have to be determined for new environments so that unusual occurrences (e.g., introduction of an introduced bioterrorism
agent) would be recognized.
 Many approaches to source tracking meet the requirements for new technologies desired by the food safety and water
resource protection communities.