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April 15, 2024Tracing the Unseen: The Critical Role of Microbial Source Tracking in Safeguarding Water Quality
Despite having one of the safest drinking water supplies in the world and among the highest standards in recreational water hygiene, a large number of Americans become ill every year from diseases spread through water. In a recently published comprehensive study of waterborne diseases in the United States, the CDC showed that every year, diseases spread through water cause 7.15 million illnesses and 6,630 deaths, costing the healthcare system more than $3.3 billion. Let’s review some concerns regarding the waterborne disease challenges that are currently being faced and how microbial source tracking can help public health professionals mitigate waterborne disease threats.
Why is Water Contamination Testing Important?
An increasing number of waterborne illnesses are related to recreational water activities, with swimming being one of the primary sources of waterborne intestinal, respiratory, ear and skin infections. Water contamination testing can help identify potentially disease-causing bacteria, fungi, viruses and protozoans being found more frequently in pools, lakes, rivers and oceans. These pathogenic microorganisms can cause serious skin and gastrointestinal illnesses and, in rare cases, exposure to flesh-eating bacteria.
The Role of Fecal Source Tracking
Beaches are often unsafe for recreational use because of elevated fecal contamination from combined sewer overflows, leaking septic systems, contaminated beach sand, pets (particularly dogs), local wildlife, migrating birds, including geese, ducks and seagulls, or nearby agricultural practices.
Getting a clearer understanding of the sources of contamination is extremely important for resource managers in their effort to control and reduce the effects of fecal pollution or prevent contamination from entering the water in the first place. This would significantly decrease the risk of individuals being exposed to fecal pollution and minimize the community costs associated with closing and reopening beaches. Traditional techniques for examining contaminated water measure the amount of fecal indicator bacteria (FIB) in a sample. An FIB test will indicate conclusively if fecal matter is present in a waterway. However, a FIB test will not identify the source of the fecal contamination.
Effective Microbial Water Testing Methods
Several types of microbial water testing tools have been developed that enable researchers and water resource management to identify the sources of fecal pollution in water, which is critical for managing and remedying water quality. Among these tools, microbial source tracking or MST, is the most powerful tool for understanding the source of contamination and mitigating its effects or stopping it altogether. MST analyzes the genetic material present in fecal bacteria using host-associated quantitative Polymerase Chain Reaction (qPCR), which is able to measure fecal pollution levels and identify the host source of the pollution. The qPCR method produces millions of copies of a specific fecal bacterial host-associated target gene found in a contaminated water sample to determine if fecal contamination from a particular host source is present and at what level.
Microbial Water Analysis Of Humans And Animal Sources
Humans and animals have digestive tracts with specific microbial communities. For example, certain bacteria found in the feces of humans may not be found in the feces of cows. The same holds true for the other animals that are commonly found to be large contributors to fecal contamination in waterways. These differences allow bacteria found in the digestive tract to be used as indicators of the host source of fecal contamination. Unique regions of DNA, referred to as DNA markers, can be established for certain bacteria in each potential host source. These DNA markers are used in qPCR microbial water analysis to selectively identify the source or sources of fecal contamination in a waterway.
Tactical Microbial Testing Of Water
When performing MST analysis, water resource managers have a general protocol for sampling recreational water from a beach or lake suspected of having fecal contamination. Typically, microbial testing of water sampling locations is selected.
Based on past sampling history or more recent activity, these locations are often potential ” hot spots” of fecal contamination. Materials, particularly sterile collection vessels, are obtained for collecting the water sample. A date is selected for sampling, usually based on weather factors, time of year, or following a particular event. After samples are collected, they are properly stored and sent to a laboratory for testing.
Laboratory Microbial Water Analysis
In the laboratory, water samples are individually vacuum-filtered through a nitrocellulose membrane that captures any bacteria present in the water sample. DNA is then extracted from the membrane, and the extracted DNA is used in the qPCR analysis along with the specific DNA marker(s) that will identify each host source of fecal contamination in the water sample. Microbial analysis of water of a single water sample can be used to identify the presence of multiple MST DNA markers and provide an exact proportion of bacteria from each potential contaminant.
Why Use Professional Microbial Source Tracking Laboratories?
Helix Biological Laboratory has extensive laboratory services and experience performing microbial source tracking (MST) analysis to detect and identify the host sources of fecal contamination in recreational waters. We have designed and developed qPCR assays with the highest degree of specificity and sensitivity, allowing us to provide informative and accurate results to our clients. Knowing the host sources and locations of fecal contamination provides our clients with the information that they require so they can proceed to take the appropriate actions to decrease fecal contamination and improve water quality.
Helix Biological Laboratory has an extensive library of DNA markers for identifying host sources of fecal contamination. These host source DNA markers include the following:
- Human
- Cow (bovine)
- Pig
- Horse (equine)
- Dog (canine)
- Deer (elk)
- Gull
- Geese
- Duck
- Chicken/Turkey
- Ruminant animals
- Avian
- Beaver
Contact Helix Biological Laboratory today for microbial source tracking services and let us assist you in detecting and identifying host sources of fecal contamination and provide the information and data you need to improve water quality along ocean beaches, lakes, rivers, streams, estuaries, and watersheds!
