The ocean gets colder, the deeper we go. The lack of light and cold water currents make the ocean floor freezing cold. This is one of the major reasons why deep ocean exploration becomes very hard for even the most geared up explorers. But there are areas, or cracks in the ocean floor where heat from the lower parts of earth’s surface rises up. Underwater volcanoes, steam columns are great examples of this. 

But, there are microbes found in these almost inhospitably warm entry points for heat. The seafloor of Guaymas Basin in the Gulf of California where tectonic plates drift apart and heat from Earth’s interior can rise up. Here, organic matter on the seafloor is ‘baked’ causing a methane influx. 

Two new studies show that distinct methane-rich deep-sea environments within the Guaymas Basin are inhabited by special microorganisms and suggest how the community may be dramatically influencing carbon cycling in the hot seafloor sediments.

Geothermal heat from the seafloor often creates an environment where water temperature fluctuates between 30-60 °C. Warm and wet environments are ideal for microbe activity and these microbes can be classified as ‘thermophiles’. 

The team details in a media release by The University of Chicago that “these exotic heat-lovers can use methane as an energy source and thrive in seascapes that are so different from most other ecosystems on Earth that they could well exist on another planet entirely.” The chemical energy in the hydrothermal vents have been debated as a possible source of power to fuel our machines, but it looks like microbes beat us to it. 

“The methane munchers and other organisms that use the chemical energy of the hydrothermal fluids are the base of the food web, without which the ecosystem would not be possible. In the first study, Teske et al. show that these methane munchers and other microbes are specially adapted to distinct thermal and geochemical regimes within the Basin,” the release details. 

Another important discovery showed that only a  few species of microbes actually used methane from their surroundings as a source of energy. Most of them just seem to like the mixture of warm geothermal vents surrounded by cold water currents. How do they survive? 

The study published in frontiers in Microbiology details that “most of the microbial diversity seems to consist of organisms, which like humans can only use reduced organic compounds for energy (such as sugars, proteins and fatty acids). These organisms, called heterotrophs, must live in some way off the biomass that rains down from the surface ocean or is produced by the methane munchers and other primary producers.”

How can creatures with such varied diets and energy requirements live in the same, almost inhospitable environment? Not many multicellular creatures call the area around geothermal vents home. In the second study, Sherlynette Pérez Castro, a postdoctoral scientist in Ruff’s lab at MBL, and collaborators show that “certain heat lovers specialize in degrading the “debris” that is released to the environment when other cells perish: organic polymers and macromolecules.”

Every cell, be it a microbial or a human cell, mainly consists of four types of macromolecules: protein, nucleic acids (DNA, RNA), lipids (fatty acids) and polysaccharides (sugars). The researchers used each one of these four compounds successively as the sole energy and carbon source to grow and identify those deep-sea organisms that can make a living on the respective compound.

They found that all of the organisms that they could cultivate in their lab experiments belonged to previously uncultivated microbial species. The experiments also showed that each polymer was nutrition for a whole food web of organisms, which explains how a single molecule can sustain a zoo of organisms, suggesting a reason for the high diversity of coexisting heterotrophs.

To their surprise, none of the 48 different cultures produced methane, a common end product of heterotrophic organisms. This could mean that the methane that is emitted at the seafloor is completely removed from the ecosystem by the microbial communities, which has implications for the deep-sea carbon cycle that remain to be explored.

This information, available on the press release, shows how microbes could hold the key to understanding how greenhouse gases like methane could be controlled in the environment. To really impact climate change, scientists have come up with biodegradable alternatives to common pollutants like plastic that are broken down by microbes. If there is a way to understand their appetite for gases like methane and harness it, it could be an excellent way to control emissions and reel in the rising atmospheric temperatures.

In a way, this discovery shows how breaking down greenhouse gases are possible in a very easy and feasible way. Microorganisms can be cultivated easily in a lab, provided they are deemed safe and could be introduced in highly contaminated environments. By consuming the greenhouses gases in a region, they could possibly help combat climate change and its related complications in a cost effective and non-invasive manner. 

With further research, we can find out the microbes that could possibly help us counter different environmental issues. Small discoveries often lead to big changes. Finding these microorganisms along geothermal vents in the ocean could hold the answer to combating a host of issues that we now face due to greenhouse gas emissions across the globe.