A world-first study has reversed the idea that the bulk of life in the ocean is fueled by photosynthesis via sunlight, revealing that many ocean microbes actually get their energy from hydrogen and carbon monoxide.
It has long been a mystery how microbes that thrive in the deepest parts of the sea, survive without sunlight. A new study from researchers at Monash University is published in the journal Nature Microbiologyshows that a distinct process called chemosynthesis — growth using inorganic compounds — fuels microbes in these dark depths.
The five-year study, led by Dr. columns.
According to Professor Greening, until now most scientists believed that microbial life in the oceans is mainly driven by photosynthesis (growth using light energy). “But what about those regions that are so deep that light cannot penetrate or that are so poor in nutrients that algae cannot thrive? We have shown in this study that chemosynthesis instead is dominant in these regions,” he said.
“Hydrogen and carbon monoxide actually ‘feed’ microbes in all the regions we studied: from urban bays to tropical islands to hundreds of meters below the surface. Some can even be found under the ice shelves in Antarctica.”
The study involved combining chemical measurements during cruises with laboratory characterization of microbial cultures. The research team also made extensive use of metagenomic sequencing, Dr. Laban said, “which tells us the genetic blueprints of all the microbes in a given area of the ocean.” “We found genes that enable hydrogen consumption across eight closely related species of microbes, known as phyla, and this survival strategy becomes more common the deeper they go through their lives.”
For this project, the researchers were inspired by their previous work on soil bacteria. Professor Greening and colleagues have previously shown that most soil bacteria can survive by consuming hydrogen and carbon monoxide from the atmosphere.
“The surface layers of the world’s oceans generally contain high levels of dissolved hydrogen and carbon monoxide gases due to different geological and biological processes. So it makes sense that oceanic bacteria use the same gases as their terrestrial cousins,” said Dr. Laban.
These findings provide insight into how life evolved. Professor Greening concludes, “The first life may have emerged in deep-sea vents using hydrogen, not sunlight, as an energy source. It is incredible that after 3.7 billion years, so many microbes in the oceans are still using this high-energy gas and we have overlooked it.” So far.”
