FOR IMMEDIATE RELEASE | January 22, 2020
Urine reuse as fertilizer is not likely to transfer antibiotic resistance
“Fate of Extracellular DNA in the Production of Fertilizers from Source-Separated Urine”
“Environmental Science & Technology
Urine is a goldmine of useful substances that can be captured and converted into products such as fertilizer. However, going “green” with urine carries some potential risks. For instance, DNA released from antibiotic-resistant bacteria in urine could transfer resistance to other organisms at the site where the fertilizer is used. Now, research published in ACS’ Environmental Science & Technology (ES&T) shows this risk is likely to be minimal.
Upcycling urine isn’t new: Farmers have collected and fertilized crops with it for millennia. The Rich Earth Institute in Brattleboro, Vermont, operates the only contemporary community-scale system in the U.S. for capturing urine and processing it into fertilizer, according to the authors of this ES&T study. In addition, some researchers have installed urine collection toilets and waterless urinals at various locations, but these are mainly for research or demonstration purposes. If the practice took hold with 10% of the U.S. population, it could save millions of gallons of flushing water and recover about 300 tons of nitrogen and 18 tons of phosphorus per day, the authors calculate. However, urine contains bacteria, including strains resistant to antibiotics. Previous studies have reported finding antibiotic-resistant DNA in urine, but it has been unclear whether that DNA could move into microbes in the environment if the urine is applied to soil. So, Krista Wigginton and colleagues conducted experiments to see if upcycling urine could spread that resistance.
In their study, the researchers used “aged” urine that had been stored in a sealed container for several months. This traditional practice increases ammonia concentration, raises pH and alters the microbial makeup of the liquid. After incubating DNA containing resistance genes for tetracycline and ampicillin in the urine, the team found that the genetic material rapidly lost 99% of its ability to confer resistance on a soil bacteria. In sum, urine-derived fertilizer poses a low risk of spreading resistance from extracellular DNA in the environment, the team says.
The authors acknowledge funding from the National Science Foundation.
The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and its people. The Society is a global leader in providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a specialist in scientific information solutions (including SciFinder® and STN®), its CAS division powers global research, discovery and innovation. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.