Project Work Plan

The premise behind BST is that genetic and visual tests can identify bacterial strains that are host specific so that the original host animal and source of the fecal contamination can be identified. Often E. coli or Enterococcus spp. are used as the bacteria targets in source tracking, as this provides a direct link with water quality standards that are usually based on one of these two indicators.

BST is a valuable tool for identifying human and animal sources of fecal pollution. The Texas E. coli BST Library (ver. 8-10) currently contains 1,309 E. coli isolates obtained from 1,185 different domestic sewage, wildlife, livestock and pet fecal sources. While this represents a significant step towards development of a statewide E. coli BST library, expansion of the library to include additional known sources from different Texas watersheds and different animal hosts is needed. The continued expansion and refinement of the Texas E. coli BST Library will provide for significant cost and time savings for the identification of NPS pollution in the development of total maximum daily limits (TMDLs) and watershed protection plans (WPPs).

In light of the increased application of BST across the state, the validity of samples processed using methods other than the modified mTEC method (EPA 1603) for use in BST analysis has come into question. The current approach utilizes only samples processed using the EPA 1603 method; however, the majority of water quality labs across Texas do not currently utilize this method. Potential cost savings, the ability to utilize more samples due to holding time constraints and the potential to advance the science of BST all warrant the evaluation of the EPA 1604, and IDEXX methods of E. coli enumeration/isolation to produce statistically similar types and counts of E. coli samples as those produced in using the EPA 1603 method.

There have been significant developments in library-independent BST methods, including bacterial genetic markers specific to different animal sources and humans (i.e., (Bernhard and Field 2000; Dick, Bernhard et al. 2005; Scott, Jenkins et al. 2005; Hamilton, Yan et al. 2006). Library-independent methods are cost-effective, rapid, and potentially more specific than library-dependent methods. Concerns with many of the recently developed library-independent approaches include uncertainties regarding geographical stability of markers and the difficulty of interpreting results in relation to regulatory water quality standards and microbial risk, since some target microorganisms are not regulated. More importantly, these library-independent methods can only detect a limited range of pollution sources and are currently not quantitative. For example, the Bacteroidales PCR (Bernhard and Field 2000; Dick, Bernhard et al. 2005) can detect fecal pollution from ruminants, humans, dogs, horses and pigs; but currently no further discrimination is possible. This method is qualitative (presence/absence), and does not identify sources of E. coli, but rather the potential sources of fecal pollution that may contribute E. coli. Despite these limitations, this method may be very useful for the rapid and inexpensive assessment of the possible sources of fecal pollution impacting a waterbody. Expanding the discriminatory ability of this approach to detect a broader spectrum of species, specifically poultry, cattle and deer will greatly enhance the applicability of this approach. Research will be conducted and peer reviewed markers from other researchers will be evaluated for possible inclusion into Texas' standard approach to conducting BST.

The state of BST science, methodologies, application and confidence has evolved greatly in the past few years. A host of new information is currently available, yet not readily distributed or known to state and federal agency personnel. This lack of information transfer has spurred the need for a statewide informational workshop geared toward bringing those in attendance up to speed on recent advances in BST technologies, methodologies, applications and results. The workshop will be targeted toward academia involved in BST analysis; state, federal, and regional agency personnel, elected officials, and other interested persons.

Due to the current and anticipated need for BST studies in Texas, the statewide BST analytical infrastructure needs to be sustained and maintained appropriately. This not only includes the needed maintenance and repairs of analytical equipment; but also the continued support, training, and retention of skilled personnel. To meet the needs of the state, BST analytical capabilities will be maintained and further supported in both the Texas AgriLife Research and Extension Center at El Paso and the Texas AgriLife Research Soil and Crop Sciences Department BST laboratories. Training needs for each individual laboratory's personnel will be coordinated to ensure appropriate technology transfer and to comparability of BST data.