Raf first tried to show that the dissolved oxygen in the samples was the result of carelessness in the sampling process. Although dissolved oxygen content appeared to be consistent across hundreds of samples, the hypothesis that the samples were contaminated could not be true. If the dissolved oxygen is not the result of contamination of the samples, then where did it come from? Raph realized that he was on the verge of an important discovery. Many of his co-authors were also skeptical, as the finding would transform scientists’ understanding of subsurface ecosystems.
Oxygen production for all
In theory, dissolved oxygen in groundwater can originate from plants, microbes or from geological processes.
The researchers used mass spectrometry, which can measure the mass of isotopes. Typically, oxygen atoms from geological sources are heavier than oxygen originating from biological sources. The oxygen in the groundwater was light, indicating that it must have come from a living organism. The most likely candidates were microbes.
The researchers sequenced the genomes of the microbial community in the groundwater sample and traced the biochemical pathways and reactions involved in producing oxygen. The answers pointed to a discovery made more than a decade ago by Mark Strauss of the University of Calgary.
Working in a laboratory in the Netherlands in the late 2000s, Strauss noticed that a type of methane-consuming bacteria often found in lake sediments and sewage sludge had a strange way of living.
Instead of absorbing oxygen from its environment like other aerobic microbes, this bacterium produces its own oxygen by using enzymes to break down nitrites (compounds containing nitrogen and two oxygen atoms). This bacterium uses the oxygen it produces to break down methane and produce energy. The process of decomposition of compounds in this way is called dismutation.
While it was previously thought that oxygen production by heterogeneous breakdown was rare in nature, recent experiments on artificial microbial communities have shown that the oxygen produced during the process of heterogeneous breakdown can escape from cells and enter the surrounding environment to be consumed by other oxygen-dependent organisms. . Ruff thinks this process is what enables microbial communities of aerobic microbes to grow in the groundwater and possibly in the surrounding soil.
Chemistry needed to live in other worlds
Ruff and his colleagues’ findings increase scientists’ understanding of how the vast subterranean biosphere evolved, as well as the role of the heterogeneous breakup in the universe’s moving composition cycle. According to Ruff, this will change our understanding of the past, present and future of underground life.
Understanding life below the surface of the earth can also be important in terms of extraterrestrial life. For example, Martian soil contains perchlorate compounds that some Earth microbes can convert into chloride and oxygen. Europa (Jupiter’s moon) has a deep frozen ocean. Sunlight may not penetrate into it, but there oxygen may be produced through the process of microbial heterogeneous decomposition.
Scientists have observed plumes of water vapor that erupt like a fountain from the surface of Saturn’s moon Enceladus. These masses probably originate from its subsurface ocean. Perhaps the creatures of other worlds continue to live with the help of the process of heterogeneous fragmentation.
