1 / 21

Improving Life through Science and Technology.

Bacterial Source Tracking Leona River Emily Martin and Terry Gentry Soil & Aquatic Microbiology Laboratory Department of Soil & Crop Sciences Texas A&M University June 27, 2013 Stakeholder Meeting. Improving Life through Science and Technology.

makana
Download Presentation

Improving Life through Science and Technology.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Bacterial Source Tracking Leona River Emily Martin and Terry Gentry Soil & Aquatic Microbiology Laboratory Department of Soil & Crop Sciences Texas A&M University June 27, 2013 Stakeholder Meeting Improving Life through Science and Technology.

  2. Where did the Bacteria (E. coli) Come From? • Potential sources • Humans • Domesticated animals • Wildlife • Methods for determining sources • Source survey • Modeling • Bacterial source tracking 2

  3. Sources of bacteria What is Bacterial Source Tracking (BST)? • Data collection and analysis to determine the sources of fecal contamination in a waterbody • Based on uniqueness of bacteria from individual sources • A variety of different methods are used • Differs from modeling in that it is not a predictive tool and does not require calibration and validation of input variables 3

  4. Library-Dependent BST Methods • Methods: • DNA fingerprinting • Enterobacterial repetitive intergenic consensus sequence-polymerase chain reaction (ERIC-PCR) • RiboPrinting® (RP) • Advantages/Disadvantages: • More discriminating • Allows ranking of sources • More expensive 4

  5. Sources Development of TexasE. coli BST Library Isolate E. coli DNA Fingerprint Add to Library 5

  6. Texas E. coli BST Library (v. 6-13) • Contains 1,524 E. coli isolates from 1,358 different human and animal samples • Collected from across Texas for BST studies including: • Waco / Belton Lake • San Antonio • Lake Granbury • Oyster Creek / Trinity River • Buck Creek • Little Brazos River Tributaries • Attoyac Bayou • Additional isolates being added from ongoing and future BST projects in other areas of Texas 6

  7. Use of Texas E. coli BST Library for Identifying Water Isolates Isolate E. coli DNA Fingerprint Compare to Library Source ID 7

  8. Comparison to Texas E. coli BST Library • Best match approach with 80% minimum similarity cutoff based on laboratory QC data • Water isolate must match library isolate ≥ 80% similarity or is considered unidentified • Identification to single library isolate with highest similarity – max similarity approach Similarity: 96.94% ERIC-PCR Similarity: 95.82% RP 8

  9. Three-way v. Seven-way Split of Results • Using the results • Is it from human sources? • Is it from livestock? • Is it from wildlife? • Biology • Large variety of wildlife • Cosmopolitan strains • Geographical and temporal differences • Statistics • Number of isolates collected • May only use three-way split for limited studies (1) Human (2) Livestock & Pets (3) Wildlife vs. Human (1) Pets (2) Cattle (3) Livestock, avian (4) Livestock, non-avian (5) Wildlife, avian (6) Wildlife, non-avian (7) 9

  10. Library-Independent BST Approach: • Genotypic detection of microorganisms based on marker genes (DNA) • Does not require known-source library • Most common approach targets Bacteroidales - - - + + + + 10

  11. What are Bacteroidales? • More abundant in feces than E. coli • Obligate anaerobes – less likely to multiply in environment • Subgroups appear to be host specific • Markers available for humans, ruminants, horse, hog • Not pathogens http://www.sourcemolecular.com/newsite/_images/bacteroidetes.jpg 11

  12. BST for Leona River • Library-independent • Target ~250 water samples from across the study area using Bacteroidales PCR for human, ruminant, horse, and hog markers • Severe drought, only analyzed ~100 samples • Limited library-dependent • Analyze E. coli from ~75 water samples from across the study area using both ERIC-PCR and RP fingerprinting • Supplement Texas E. coli BST Library with known-source fecal samples from the watershed 12

  13. Monitoring Stations 13

  14. Leona BST Samples 14

  15. Bacteroidales BST Results Stream Samples (n=71) 15

  16. Bacteroidales BST Results Fish Hatchery Samples (n=29) 16

  17. Known-Source Fecal Additions from Leona River • DNA fingerprinted 201 total isolates (ERIC-RP) from 201 individual fecal samples • Ultimately, 77 isolates were validated and added to the Texas E. coli BST Library • Domesticated animals and livestock (36 total) • Beef cattle (15), horses (5), chickens (4), dogs (3), goats (4), sheep (3), and ducks (2) • Wildlife (41 total) • Feral hog (17), deer (9), coyote (4), fox (4), various birds (4), raccoon (2), and road runner (1) 17

  18. E. coli BST Results Stream Samples (n=77) – 3-Way Split 18

  19. E. coli BST Results Stream Samples (n=77) – 7-Way Split 19

  20. BST Summary • Library-Independent Analysis • Limited detection of source-specific markers • Human marker only detected at wastewater plants • Limited Library-Dependent Analysis • Major E. coli sources in watershed appear to be wildlife (feral hogs, coyote, and deer) as well as domesticated animals (cattle) • Texas E. coli BST Library additions from Leona • Significant effort toward to include numerous samples from major potential sources in the watershed 20

  21. Questions? Emily Martin and Terry Gentry 2474 TAMU Texas A&M University College Station, TX 77843 Office: (979) 845-5323 Lab: (979) 845-5604 Email: emartin@ag.tamu.edu tgentry@ag.tamu.edu 21

More Related