July 21, 2018

What is Microbial Source Tracking?

In the modern era, humans are in a never ending battle for the space to properly allocate resources. Often times, the result is environmental overlap, with people, wildlife, domestic animals, and life-sustaining resources all colliding and competing for the same locations. One major problem caused by this intersection is the contamination of surface water by fecal matter. Whether the water is used for drinking, for recreating, or even in the harvesting of seafood, there is a high level of risk for the human population making use of it.

Microbial source tracking (MST), also known as fecal source tracking, is a method currently used to discover the source of any fecal bacteria found in the bodies of water in a given area. As the population and need for viable land grows, this process is becoming increasingly important because people can become ill from swallowing or coming into contact with the contaminated water in lakes, rivers, and oceans. Determining the source of the harmful bacteria is one of the first lines of defense in controlling, and therefore minimizing, the risks associated with infested water. This is because the specific health risks can be assessed once the origin is understood. Only then, the actions which are necessary to remedy the problem can be implemented.

Some of the most common potential sources for bacterial pollution are wastewater discharges, combined sewer overflows, poor livestock management, litter, and wildlife. According to the State of Washington Department of Ecology, the MST techniques that are used to determine which of those sources is to blame for a water issue are broken down into two categories:

  • Molecular and biochemical techniques hunt for certain genes that can be linked to a specific host and assume that there are distinct features of fecal bacteria which allow scientists to identify the source of the contamination.
  • Chemical methods are based on the detection of specific chemicals which help to determine their exact sources, and are usually not found in unpolluted waters.

Although it is considered an emerging science, fecal source tracking is recognized as a process that provides useful and detailed information which is unavailable through other methods. It has not yet replaced conventional source tracking entirely, but it is being employed on a wider scale alongside conventional techniques. In their article assessing MST, the American Society for Microbiology stated that the efficacy of using traditional indicators is limited when it comes to predicting the presence of human or animal waste, as well as the impact and subsequent health risks. This is why there is a need for the specificity of MST. With the development of testing methods that are able to conclusively define particular sources of problematic organisms, the usefulness of bacterial indicators as risk assessment tools is greatly enhanced.

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