Laboratory Analysis - Bacterial Source Tracking

Source tracking includes a wide spectrum of laboratory methods for determining the source of a pollutant. Bacterial Source Tracking (BST), also referred to as Microbial Source Tracking (MST), is a set of methodologies designed to identify the sources of fecal contamination.

MapTech, Inc. offers turnkey service in BST – from the monitoring design through final analysis. MapTech established the Environmental Diagnostics Laboratory (EDL) in part to focus on the emerging field of BST. Operational since 2001, the EDL occupies 4,000 square feet in MapTech’s recently completed facility.

Library-Based Methodologies

All BST methods in use today that produce quantifiable results (i.e., percent contribution of load from specific sources) are library-based.

The library-based technique uses a databank of information (a "library") that is made up of fecal bacteria from samples of known origin (e.g., human, pet, livestock, and wildlife). As new source samples of known origin are collected, they are added to the databank in order to augment the source library. Bacteria from the water samples are compared to the known source library using BST analysis.

The EDL is experienced in a variety of library-based BST analysis methods...
Antibiotic Resistance Analysis (ARA)
First and foremost, the Antibiotic Resistance Analysis (ARA) methodology provides three main benefits:
  • low cost per sample
  • speedy analysis
  • high number of isolates tested
The ARA method is recommended for Total Maximum Daily Loads (TMDLs).
Polymer Chain Reaction (PCR)
Polymerase Chain Reaction (PCR) ribotyping focuses on segments that have sequences of repeated DNA bases, which may vary between bacteria from different sources. In theory, this DNA fingerprinting method is similar to other molecular techniques but allows more samples to be analyzed in a shorter amount of time, and at a lesser expense, than traditional molecular methods.
Pulsed Field Gel Electrophoresis (PFGE)
Pulsed Field Gel Electrophoresis (PFGE) is the "gold standard" of BST analysis. The precise analysis provided by PFGE is unparalleled, but the process does require a greater investment of funds and time.
Nutrient Utilization Pattern (NUP)
The Nutrient Utilization Pattern (NUP) technique was developed by MapTech in order to provide an option between ARA and PFGE in terms of both time and cost. Because it utilizes an electronic plate reader and does not rely upon a lab technician’s judgment, many consider this method to be "foolproof". While PCR and PFGE are genotypic methodologies, ARA and NUP are phenotypic techniques.

Non-Library-Based Methodologies

All non-library-based BST methods in use today are designed to indicate the presence of specific sources. They focus on the identification of specific markers (e.g., chemical or viral) in the water column that indicate the likely presence of fecal contamination from a specific source.

MapTech has incorporated fluorometry into its BST toolbox as a useful non-library-based method for determining the presence of human wastewater. Fluorometry is used to identify optical brighteners in the water column. Optical brighteners are used in laundry and dishwasher detergents, but are not typically found in the environment. The presence of high levels of optical brighteners indicates contamination from human wastewater.


MapTech’s Environmental Diagnostics Laboratory is a successful leader in the development of source tracking technologies. This leadership has been born out with recognition from foreign agencies pursuing technology transfer as well as the award of Small Business Innovative Research (SBIR) grants from USDA. With the conclusion of the current SBIR, it is expected that MapTech will go on to Phase 2.

MapTech is contracted to conduct all of the BST analysis for the Commonwealth of Virginia. To date, the EDL has analyzed tens of thousands of source and water samples to support the Total Maximum Daily Load (TMDL) effort in the state.

In addition, MapTech and its EDL have completed BST work in Arkansas, Maryland, North Carolina, Pennsylvania, and Virginia. In addition, MapTech has completed other contract work in several other states.

Sample Collection

The Environmental Monitoring Services (EMS) division of MapTech provides time-efficient and cost-effective sample collection for BST projects. Source and water collection techniques adhere to strict standardized procedures that are designed to provide accurate and thorough sampling.

Research & Development

In collaboration with Dr. Charles Hagedorn of the Department of Crop and Soil Environmental Sciences at Virginia Polytechnic Institute & State University (Virginia Tech), MapTech has funded graduate student researchers in their Masters and Doctorate programs. Efforts have included research in both molecular and non-molecular techniques. In addition to laboratory techniques, MapTech has enhanced data analysis methodologies through introducing new statistical analysis tools and improving Quality Assurance (QA) procedures.

MapTech’s Research Division is strongly focused on developing source tracking methodologies. Current investigations involve a non-library-based BST methodology which will result in a more cost-effective and time-efficient analysis.

Getting Started

In areas where these technologies have been established, MapTech offers regionally-specific analysis methodologies. In areas where these technologies have not been tested, MapTech can develop regionally-specific analysis methodologies, based on our time-tested procedures. MapTech disseminates these technologies as laboratory services, and as kits (i.e., laboratory and statistical analysis tools) to be used in the client’s laboratory, after proper training.