How frugal microbes live on minimal energy
How can microorganisms survive when there is hardly any energy or nutrients available? In a new review article, researchers from Linnaeus University and University of Jena propose the concept of microbial frugality, a new framework that explains how microorganisms live under the extremely energy-poor conditions of groundwater whilst still maintaining key material cycles.
Beneath our feet lies one of the Earth’s largest and, at the same time, least researched habitats. Vast microbial communities thrive in aquifers, rock pores and deep crevices – without sunlight, with only a few nutrients and operating at the very limits of what is energetically possible. In their joint review article, Mark Dopson of Linnaeus University and Kirsten Küsel of University of Jena summarize the current state of knowledge in the field.
Microbial frugality
At the heart of the paper lies the concept of »microbial frugality«. It describes evolutionarily developed traits that enable microorganisms to minimise their energy consumption, utilise available resources efficiently and survive in the long term even under chronic energy deprivation.
”The concept of microbial frugality describes how deep life is adapted to the extremely low availability of energy such that they can survive for long periods. These adaptations include having a small cell that requires less energy to maintain and reproduce and a reproductive strategy that can be halted and restarted based upon energy availability” says Mark Dopson, professor at the Department of Biology and Environmental Science at Linnaeus University.
Similar adaptations around the world
For the review, they analysed numerous international studies on groundwater ecosystems and synthesised their findings within a shared conceptual framework. This revealed that microorganisms worldwide have developed similar adaptations to cope with chronic energy and nutrient shortages.
Many groundwater microorganisms grow extremely slowly, utilise different energy sources flexibly, or rely on close metabolic partnerships with other microorganisms. At the same time, they remain in an energy-saving standby state, which allows them to react immediately to short-term nutrient inputs or to mobilise stored energy reserves. Together, these characteristics enable them to live permanently under conditions that were long considered virtually uninhabitable.
Implications for climate and water resources
The significance of these findings extends far beyond microbiology. Groundwater is the Earth’s largest reservoir of liquid fresh water and supplies billions of people worldwide with drinking water. At the same time, the microorganisms living there influence key material cycles: they sequester carbon, degrade methane and regulate the transformation of nitrogen, sulfur and iron compounds. In doing so, they make a significant contribution to the chemical stability of groundwater ecosystems and to the regulation of climate-relevant gases.
The authors regard their framework as an important basis for gaining a better understanding in future of the role of groundwater in global material cycles, in water quality and within the climate system.
”These microorganisms are among the most hidden, yet at the same time most important, players on Earth. Anyone who wants to understand and protect the future of our groundwater resources must also take into account the communities that exist deep underground under conditions of chronic energy deprivation” says Kirsten Küsel, professor at the University of Jena.
More information
Link to the study: "Groundwater microbial communities across the terrestrial subsurface" published in Nature Microbiology.
This article is based on a press release from University of Jena.