Stromatolites – Fossils of Earliest Life on Earth – May Owe Their Very Existence to Viruses

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Stromatolites at Shark Bay

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Stromatolites at Shark Bay, Western Australia. Credit: UNSW Sydney/Brendan Burns

As the Mars Rover sets out to try to find proof of life on another world, researchers back on Earth recommend infections played a crucial function in producing stromatolites, our world’s earliest lifeforms.

It might discomfort us to hear this throughout a lethal viral pandemic, however life as we understand it on this world might never ever have actually happened if it weren’t for infections, researchers studying billion-year-old ‘living rocks’ state.

In a paper released in the March concern of Trends in Microbiology, a group of researchers from UNSW Sydney and the United States took a look at proof of the world’s earliest lifeforms in fossils referred to as stromatolites, layered limestone rocks frequently discovered in shallow waters around the world. They wished to comprehend the system that led nests of single-celled organisms referred to as microbial mats to develop these interesting rock structures.

And they think infections might be the missing out on piece of the puzzle that might assist describe how a soft microbial mat shifts – or lithifies – into the difficult stromatolite functions that prevail in such locations as Shark Bay and the Pilbara, Western Australia.

Co-author on the paper, Associate Professor Brendan Burns from UNSW’s Australian Centre for Astrobiology, states stromatolites are among the earliest recognized microbial environments, going back some 3.7 billion years.

“Stromatolites are pervasive in the fossil record and are some of our earliest examples of life on Earth,” he states.

“The microbial mats that produced them were mainly comprised of cyanobacteria, which utilized photosynthesis – like plants do – to turn sunshine into energy, while producing a lot oxygen with time they altered the early Earth’s environment to make it habitable for complicated life.

“You could say we owe our very existence to these living rocks.”

Stromatolite Shard

A fragment of stromatolite rock discovered at Shark Bay revealing layered sediments that was produced by microbial mats billions of years back. Credit: UNSW/Brendan Burns

A/Prof. Burns and his associates wished to comprehend the system behind the microbial mats lithifying into stromatolites, not just since so little is understood about the procedure, however since of what this might contribute to our understanding about life on Earth – and perhaps other worlds.

“If we understand the mechanisms of stromatolite formation, we will have a better handle on the impact these ecosystems had on evolution of complex life,” he states.

“This understanding might assist us much better analyze biosignatures – which you might call chemical or molecular fossils – that supply hints to the activities of early life, billions of years back.

“It also has the potential to help us look for life on other planets – one of the jobs of the Mars 2020 mission is to look for evidence of biosignatures in Martian rock samples.”

In the paper, the authors postulate that microbial mat shift from soft cells to rock is improved by interactions with infections.

“We propose viruses may have a direct or indirect impact on microbial metabolisms that govern the transition from microbial mat to stromatolite,” he states.

In the direct effect circumstance, infections penetrate the nucleus of the cyanobacteria and affect the host metabolic process, placing and getting rid of genes that increase the physical fitness of the infection and the host at the very same time.

“This, in turn, increases survival of the microbial mat and selects for genes that potentially influence carbonate precipitation – basically the process of microbes pouring the concrete to make their stromatolite apartment blocks,” A/Prof. Burns states.

In the indirect circumstance, the researchers speak about a procedure referred to as viral lysis, where infections get into living cells and activate the disintegration of their membranes and release of contents – successfully causing cell death.

“We think viral lysis may release material that promotes metabolism of organisms which results in mineral precipitation and eventual stromatolite formation.”

Whether infections trigger the microbial mats to solidify into stromatolites straight or indirectly, or a mix of both, A/Prof. Burns states more research study is required.

“We’re wishing to do more research studies in the laboratory to evaluate this.

“We want to be able to identify what viruses are actually involved and see if we can then manipulate potential virus-host interaction to find out whether or not they can, in fact, change some of the metabolisms that might result in stromatolite formation,” A/Prof. Burns states.

Reference: “Between a Rock and a Soft Place: The Role of Viruses in Lithification of Modern Microbial Mats” by Richard Allen White III, Pieter T. Visscher and Brendan P. Burns, 9 July 2020, Trends in Microbiology.
DOI: 10.1016/j.tim.2020.06.004



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