The U.S. Geological Survey Ohio Water Microbiology Laboratory (OWML), part of the USGS Ohio-Kentucky-Indiana Water Science Center, is a Biosafety Level II water research lab in Columbus, Ohio. Its scientists detect microbial indicators and pathogens in water and study what controls where and how often they occur. The lab runs its own projects, supports other USGS offices and national programs, and works with federal, state and local agencies, universities and utilities — helping design studies, analyze samples and interpret results under strict quality-control procedures that track every sample from arrival to reported result.
USGS biologists and technicians at work in the Ohio Water Microbiology Laboratory. Photograph by Amie Brady, USGS.
Signs of fecal contamination
Fecal indicator organisms — bacteria and viruses — signal that water may be contaminated with feces and that harmful organisms may be present. The lab measures them with culture-based and molecular methods to judge the risk of swimming in or drinking from a water source.
| Indicator | What it tells you |
|---|---|
| Total coliforms | found in soil, water, plants and the intestines of people and animals; a general sign of bacterial contamination |
| E. coli | a coliform living in the intestines of warm-blooded animals; direct evidence of fecal contamination |
| Enterococcus | intestinal bacteria that persist longer in water than coliforms; used to gauge recreational water quality and trace contamination moving through groundwater |
| Coliphages | viruses that need coliform bacteria to reproduce; may better reflect how viruses survive and travel than bacteria do |
Total coliforms (yellow under ordinary light, left) and E. coli (fluorescent under ultraviolet light, right) detected with the Colilert method. Photograph by Braden Lanier, USGS.
Where the contamination comes from
Standard culture tests can't say what the fecal contamination came from. Microbial source tracking can. Each kind of warm-blooded animal — shaped by its diet, body temperature and physiology — carries its own gut microbes with distinctive genetic sequences. The lab filters water samples, extracts the DNA caught on the filter, and runs quantitative PCR (qPCR) tests for genetic markers from humans, dogs, cattle, horses, pigs or birds.
The microbial source tracking workflow (USGS).
Environmental DNA
Living things shed genetic material — environmental DNA (eDNA) — in skin and mucus cells, gametes, waste and shell material. Detecting it reveals an organism's presence without having to catch it, helping find rare species, track invasive ones and assess the health of streams and wetlands. The lab uses qPCR to detect eDNA from several species of invasive carp, several threatened or endangered mussels and some aquatic invertebrates.
Toxic algal blooms
Cyanobacterial harmful algal blooms (cyanoHABs) are a growing global water-quality problem that threatens people and wildlife. Despite the name, they aren't caused by true algae but by cyanobacteria, photosynthesizing bacteria common in fresh water. Some produce cyanotoxins — potent neurotoxins, hepatotoxins, cytotoxins and endotoxins — and blooms can require extra toxin monitoring in drinking-water sources and swimming areas. The lab uses qPCR to detect cyanobacterial genes, showing which types are present and whether they could make toxins, and enzyme-linked immunosorbent assays (ELISAs) to measure the toxins directly.
A cyanobacterial harmful algal bloom at Maumee Bay State Park, Oregon, Ohio, in 2013. Photograph by Donna Francy, USGS.
Earthy tastes and smells
Cyanobacteria and filamentous bacteria of the genus Actinomyces, common in soil and water, produce geosmin and 2-methylisoborneol (MIB), the compounds behind earthy tastes and odors in drinking water. They aren't harmful, but they can make people think their water is unsafe. The lab counts Actinomyces by culture and uses qPCR to detect the genes that make these compounds.
Predicting when to close a beach
Swim advisories and beach closings are based on fecal indicators such as E. coli and Enterococcus, or on cyanotoxin levels. But culture tests take 18 to 24 hours, and toxin tests, though faster, need trained staff and special equipment — often too slow to warn swimmers in time. Predictive models solve that by combining the lab's past results with real-time measurements such as temperature, rainfall and turbidity to estimate water quality in near-real time. The lab's scientists have built models for cyanotoxins, fecal indicators and Enterococcus.
Sources
- U.S. Geological Survey: "The U.S. Geological Survey Ohio Water Microbiology Laboratory," USGS Fact Sheet; a work of the United States government in the public domain.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
1
0
0
0
Comments
