Billions of years ago, life started to surface on our planet despite the lack of oxygen, a phenomenon that has fascinated researchers for decades. According to a new study, a deadly compound played an essential role in the development of microbes.
A team of researchers has studied a mat of photosynthetic microbes that can be found in a lake that has impressive levels of salt and is completely free of oxygen. Microbial mats have been present on Earth for at least 3.5 billion years, despite the fact that there was no oxygen until 2.5 billion years ago.
Researchers have been able to learn important data about ancient microbes because they fossilize into stromatolites. Previous work associated with stromatolites and extremophiles has uncovered key information, including potential alternatives to oxygen. Hydrogen, sulfur, and iron were deemed to be potential candidates.
However, a major discovery was represented by the presence of arsenotrophy in two hypersaline lakes located in California, which made arsenic a potential contender. Stromatolites found in Western Australia have revealed that light and arsenic were used in photosynthesis during the Precambrian period.
The microbes observed by the researchers in the mat found in Laguna La Brava, Chile, share similar traits with a sulfur bacteria that is found in arsenic-rich lakes and is capable of photosynthesis by oxidizing arsenite into a different compound called arsenate. Samples of water that surround the mats have revealed the presence of arsenic.
It can be argued that the microbes offer an interesting look at the way in which early life forms appeared and thrived on our planet despite the presence of harsh environmental conditions. Initial tests have shown that the La Brava microbes can process arsenic and sulfur, with arsenate reduction appearing to be dominant. Further research will take place in the future.
The study has been published in a scientific journal.