Billions of years ago, before oxygen was readily available, the infamous toxin arsenic could be a compound that breathes new life into our planet.
In the Atacama Desert of Chile, at a place called La Brava in Laguna, scientists are studying a purple ribbon of photosynthetic microorganisms that live in a hypercylene lake that is permanently free of oxygen.
“I’ve been working with microbial mats for about 35 years or more,” says Peter Wischer, a geologist at the University of Connecticut.
“This is the only system on earth where I can find a microbial mat that works perfectly in the absence of oxygen.”
Microbial mats, which are fossilized in stromatolites, are at least a billion on Earth. have been abundant for billions of years, and yet, for the first billion years of their existence, there is no oxygen for photosynthesis.
How these life forms survived such extreme conditions is still unknown, but researchers investigating stromatolites and extreme phylloxera have discovered a handful of possibilities.
While iron, sulfur, and hydrogen have long been suggested as possible substitutions for oxygen, arsenic did not become a contender until it was found in California’s Hypersalin Searles Lake and Mono Lake.
Subsequently, the stromatolites of the Tambiana formation of Western Australia have revealed that light and arsenic light at one time were a valid alternative to photosynthesis in the prepembrian. The same cannot be said of iron or sulfur.
Just last year, researchers discovered an abundance of life forms in the Pacific Ocean that also breathe arsenic.
La lava life is also closely related to that of the purple sulfur bacterium Ectothorhodospira sp., Which was recently discovered in an arsenic-rich lake in Nevada, and the compound appears to be photosynthetic by oxidizing arsenite in a different form-sarnate.
While further research is needed to examine whether La Brava microorganisms also metabolize arsenite, preliminary research has found that the water flowing around these mats is heavily loaded with hydrogen sulfide and arsenic.
If the authors are right and the La Brava microorganisms are indeed ‘breathing’ arsenic, these life forms would be the first to do so in a permanent and completely oxygen-free microbial mat, which we would expect in a prehistoric environment.
In this way, his mats are an excellent model for understanding some of the life forms of potential life on our planet.
Genomic research suggests that La Brava mats contain tools for arsenic and sulfur metabolism, the authors say, adding that a reduction in its arsenal seems more effective than a reduction in its sulfate.
Regardless, they say there is evidence that both pathways exist, and that this could have been enough to support the expanded microbial mats in the early days of life on Earth.
If the team is right, then we may need to expand elsewhere in search of life.
“Finding evidence of life on Mars, [scientists] “They will look at iron and maybe they should look at arsenic,” says Wischer.
It’s really more than just a poison.
The study was published in Communication earth and environment.
This article was originally published by Science Alert. Read the original article Here.
