Researchers Sequence DNA In Sewage Samples

Researchers have discovered a new way to track sewage dumped in waterways and pinpoint whether water pollution comes from human fecal matter.

As Science Mag put it, "Microbiologists have a new way to tell whose sh-t is dirtying the waters."

The insight behind this new approach is that sewage from each city has different characteristics.

"A survey of sewage across the United States shows that every city has a distinct microbial character that can reveal signs of health, such as how obese its residents tend to be. Dozens of the microbes identified in the survey are common throughout the United States, and could provide better ways to tell whether bacterial pollution comes from humans," the report said.

The research began with an effort to understand bacteria in the human gut, which are known as microbiomes.

"Mitchell Sogin, a molecular evolutionist at the Marine Biological Laboratory in Woods Hole, MA, and Sandra McLellan, a microbiologist at the University of Wisconsin, Milwaukee, wanted to take a much broader view and study the microbiomes of entire human communities. In addition, they were looking for a better indicator of human fecal pollution," the report said.

This is where they needed assistance from wastewater treatment facilities. "They recruited wastewater treatment plant operators from 71 U.S. cities to collect more than 200 samples of incoming sewage. They then sequenced DNA in the samples and determined its origin," the report said.

The researchers published their findings in mBio. "We demonstrate that geographically distributed U.S. populations share a small set of bacteria whose members represent various common community states within U.S. adults. Cities were differentiated by their sewage bacterial communities, and the community structures were good predictors of a city’s estimated level of obesity," the study said.

The upshot?

"Our approach demonstrates the use of sewage as a means to sample the fecal microbiota from millions of people and its potential to elucidate microbiome patterns associated with human demographics," the study said.

Around 15 percent of the sewage DNA belonged to microbes found in humans.

"Using a technique developed by Sogin and his colleagues, which can more precisely determine which bacteria are present in a large sample of feces, the researchers identified about 60 types of bacteria that were common to people in all of the cities. Because they seem to be found wherever humans are, these 60 may be a reliable way to determine if human feces are contaminating a waterway," Science Mag reported, citing McLellan.

Previous research indicates that waste contains data about drug use, the spread of disease, and the general state of public health, the Boston Globe recently reported.

MIT scientists are working on a project called "underworlds" trying to glean data about city residents based on their sewage, in a process they believe could eventually help predict epidemics before they happen.