Microorganisms play a pivotal role in sustaining the sulfur cycle and influencing climatic phenomena. Recent research has uncovered a range of versatile sulfate-reducing microbes with the unprecedented capability to reduce sulfate and simultaneously respire oxygen, overturning established scientific beliefs. (Depicted through an artistic interpretation.)
Investigations into microorganisms with environmental significance have revealed a diversity beyond what was formerly perceived.
Scientists have uncovered a significantly higher level of biodiversity among microorganisms with environmental importance than what was previously understood, estimating this diversity to be at least 4.5 times greater. These insights have been disseminated in the esteemed publications Nature Communications and FEMS Microbiology Reviews.
Microorganisms, although frequently neglected, play an integral role in numerous climate-related processes. This is evidenced by the remarkable variety of species found in bacterial and archaeal groups, sometimes referred to as “primitive bacteria.” Sulfate-reducing microbes, for instance, are responsible for converting a third of the organic carbon in marine sediment into carbon dioxide, releasing hydrogen sulfide, which is toxic. However, sulfur-oxidizing microbes efficiently utilize hydrogen sulfide as an energy source, thereby neutralizing it.
“These mechanisms are also critical in environments like lakes and bogs, and they even have implications for human gut health, helping to maintain the equilibrium of nature and well-being,” states Prof. Michael Pester, leader of the Microorganisms Department at the Leibniz Institute DSMZ and professor at the Institute of Microbiology, Technische Universität Braunschweig. Detailed scrutiny of one such novel microorganism’s metabolism has exposed a level of multifunctionality previously deemed unachievable.
A substantial diversity in sulfate-reducing microorganism species has been identified, now recognized across 27 different phyla in bacteria and archaea, surpassing the six known previously. Attribution: DSMZ
The Essential Equilibrium of the Sulfur Cycle
The sulfur cycle stands as one of the planet’s most fundamental and ancient biogeochemical cycles, deeply intertwined with the carbon and nitrogen cycles, highlighting its significance. Sulfate-reducing and sulfur-oxidizing microorganisms primarily propel this cycle. Globally, sulfate reducers transform roughly a third of the organic carbon deposited on the ocean floor annually. In response, sulfur oxidizers consume about one-fourth of the oxygen present in marine sediments.
Disruption in these ecosystems can lead to rapid deoxygenation and the accumulation of toxic hydrogen sulfide, causing the emergence of ‘dead zones’ where marine flora and fauna cannot survive. Such disturbances result in not only economic losses, such as those impacting fisheries, but also societal harm by destroying key leisure spaces. Understanding the microorganisms that regulate the sulfur cycle and their mechanisms is therefore of great importance.
The findings indicate that the variety of sulfate-reducing microorganisms spans at least 27 phyla. Beforehand, this diversity was limited to only six known phyla. For perspective, there are currently 40 recognized phyla within the animal kingdom, with all vertebrates classified under just one phylum, the Chordata.
Diagram illustrating the decomposition of plant pectin – via sulfate reduction and oxygen respiration by a newly identified acidobacterium. Courtesy of DSMZ
Novel Multifunctional Bacterial Species Unearthed
This groundbreaking research has successfully classified one of these innovative “sulfate reducers” within the lesser-known acidobacteriota phylum, observing it within a bioreactor.
Utilizing state-of-the-art techniques from the field of environmental microbiology, the study demonstrated that these bacteria can harness energy from both sulfate reduction and oxygen respiration, a duality not seen in previously known microorganisms. Concurrently, the study showed these acidobacteriota can also decompose complex plant polysaccharides such as pectin, an ability not traditionally associated with “sulfate reducers.”
This research subverts long-standing assumptions in microbiology textbooks, revealing that complex plant compounds can be broken down anaerobically not only by the combined efforts of diverse microbes but also by a singular bacterial species through a more direct route.
Dr. Stefan Dyskma (left) and Prof. Dr. Michael Pester by a bioreactor at the DSMZ where the novel “sulfate reducers” were investigated. Image credit: DSMZ
Further research is ongoing at the DSMZ and Technische Universität Braunschweig to understand how these discoveries influence the interplay between the carbon and sulfur cycles and their connections to climate-critical processes.
Citations:
“Oxygen respiration and polysaccharide degradation by a sulfate-reducing acidobacterium” by Stefan Dyksma, and Michael Pester, 10 October 2023, Nature Communications.
DOI: 10.1038/s41467-023-42074-z
“Global diversity and inferred ecophysiology of microorganisms with the potential for dissimilatory sulfate/sulfite reduction” by Muhe Diao, Stefan Dyksma, Elif Koeksoy, David Kamanda Ngugi, Karthik Anantharaman, Alexander Loy, and Michael Pester, 05 October 2023, FEMS Microbiology Reviews.
DOI: 10.1093/femsre/fuad058
Table of Contents
Frequently Asked Questions (FAQs) about multifunctional microorganisms
What does the discovery of the 3-in-1 microorganism mean for microbiology?
The discovery indicates that a single microorganism can reduce sulfate, respire oxygen, and decompose complex plant carbohydrates, challenging the previously understood limitations of microbial metabolic processes and indicating a more complex biodiversity than known before.
How does this new microorganism affect our understanding of the sulfur cycle?
This microorganism exemplifies that the sulfur cycle is more intricate than previously thought, with single species capable of performing multiple roles in the cycle, thus potentially affecting the balance of marine ecosystems and the global climate.
What is the significance of the multifunctional bacterial species found?
The significance lies in its ability to perform both sulfate reduction and oxygen respiration, which are typically mutually exclusive in known microorganisms, suggesting new mechanisms of microbial contribution to biogeochemical cycles.
How many phyla of sulfate-reducing microorganisms have been discovered?
Researchers have now identified sulfate-reducing microorganisms across 27 different phyla, a significant increase from the six previously known phyla, highlighting a greater diversity in this group of microorganisms.
What implications does the research have on climate-related processes?
The findings suggest that these multifunctional microorganisms could have a profound impact on the carbon and sulfur cycles, which are essential for understanding climate dynamics and may lead to new insights into mitigating environmental and climate challenges.
5 comments
this research from DSMZ and Technische Universität Braunschweig is groundbreaking, curious how it will affect the future studies.
there’s a typo in the second paragraph, “sulphur” is spelled differently than “sulfur” in the rest of the text. Just a heads up!
really interesting stuff, didn’t realize bacteria could be so versatile but i guess mother nature is full of surprises!
Wow this is a game changer for science… these microorgnaisms are way more complex than we thought.
got to say, the impact on climate change models could be significant with this discovery, we may need to rethink some of our predictions