Methane-eating microbes discovered in canals of Amsterdam

NESSC-study discovers new microbes living in the canals of Amsterdam that consume methane gas.

Scientists of Radboud University and Utrecht University investigated how much methane gas the canals in Amsterdam are producing. To their surprise, they discovered methane-eating microbes living in slimy biofilms on the canal walls. Most likely these microbes explain why the canals in Amsterdam produce relatively little methane gas. The researchers also found that the canals are remarkably clean: the canal water was hardly polluted by nitrogen, phosphate or organic materials. The new research has been published in science journal Environmental Microbiology.

Koen Pelsma

Shallow waters, like lakes, rivers or canals, often form a source of methane gas, a strong greenhouse gas estimated to be 86 times more powerful than carbon dioxide (CO2). Yet little is known about the microbes living in these waters and whether they produce or consume methane gas.
For this purpose, NESSC-researchers of Radboud University and Utrecht University started to map the world famous canals of Amsterdam. They took samples of the water, the soil and the canals walls at several locations in Amsterdam, such as the Bloemgracht, Prinsengracht and Artis. Surprisingly, the canals emitted relatively little methane, the researchers found. Likely this is caused by methane-eating microbes that the scientists discovered in the water and in biofilms on the canal walls.

“On these canal walls we discovered a new species of bacteria consuming methane. These bacteria, living in a biofilm on the wall, likely capture and consume methane gas being produced in the canal,” says Koen Pelsma, PhD-student at Radboud University and first author of the publication. “In addition, the canal bottom releases only a little methane, because of the low accretion of organic materials, like dead plants. These plants rot on the bottom, and in this process bacteria produce methane gas.”
“In fact, we found the canals to be surprisingly clean. Pollution with nitrogen or phosphate was low. We also measured enough oxygen in the water for fish to thrive. Most likely this is because wastewater treatment in the Netherlands is of a relative high standard.”

Sampling water- and soil in the canals of Amsterdam

Methane filter
The discovery of methane-eating microbes living on the walls of Amsterdam’s canals offers interesting future possibilities. The bacteria live on the portion of the wall that’s under water. “If it would be possible to increase the surface of the area where these bacteria live, it could potentially be used as a methane filter,” says microbiologist dr. Cornelia Welte (Radboud University). The next step for the researchers is to investigate canals of other Dutch cities. Pelsma: “We already have plans to sample canals in the cities of Delft and Utrecht. Every canal is likely different.”

Amsterdam urban canals contain novel niches for methane-cycling microorganisms
Environmental Microbiology, 2021.
Koen A.J. Pelsma, Michiel H. in ’t Zandt, Huub J.M. Op den Camp, Mike S.M. Jetten, Joshua F. Dean, Cornelia U. Welte