Microbes Were Once Responsible for the Biggest Mass Extinction Ever Experienced by Earth, Claim Researchers

For most people, microbes are associated with diseases, but a team of researchers says these tiny beings' ability to cause havoc shouldn't be ignored. In large numbers, they could change the face of Earth, stated Live Science. Findings regarding this 'impact' by microbes were published in the journal Proceedings of the National Academy of Sciences.

The end-Permian extinction has been determined as one of the biggest mass extinction events ever experienced by Earth. The event started 252 million years ago and resulted in the wiping out 96 percent of ocean life and 70 percent of land-based life forms. The whole phenomenon took place in only 60,000 years. Several reasons for this event have been proposed by researchers, from massive meteor impacts to the rift in supercontinents. The study claims that the event took place due to Methanosarcina, a methane-producing bacteria.

Researchers analyzed certain rocks from Meishan, China, dating back to the period when the end-Permian extinction was unfolding. The results showcased that atmospheric carbon dioxide levels rapidly increased around the time of extinction. Before this study, researchers believed that the Siberian Trap, a set of volcanic eruptions that occurred during that period caused the release of extra carbon dioxide. However, experts associated with the study noted that the CO2 levels increased at faster-than-exponential rates. This does not align with what should have possibly happened if volcanic eruptions caused the increase in CO2.

If the Siberian Trap was responsible, then there would have been a big burst of carbon dioxide and then a gradual decay. This implied to the experts that there was a biological cause. Researchers believe Methanosarcina ate carbon-based chemical acetate, resulting in the large-scale production of methane. Thereafter, the methane was converted to CO2 by processes conducted by other microbes. These processes must have used up practically all the free oxygen present in the environment. The oxygen-starved conditions facilitated the end-Permian extinction. "It could have been a very-long-term successive disruption of all of Earth's ecosystems," Gregory Fournier, a biologist at the Massachusetts Institute of Technology shared.

To verify the theory, researchers examined the rates of gene mutation in Methanosarcina. The results indicated that the bacteria acquired genes to make methane from acetate some 250 million years ago, just around the time of the end-Permian extinction. Furthermore, the geological sediments also showcased that volcanic activity had amplified the quantity of nickel, which was required for critical metabolic functions by the bacteria.

Researchers also claim that the conditions put in place by volcanic eruption enhanced the population of methane-producing bacteria. "The volcano was the catalyst or the primer for the much larger release of CO2 that was caused biologically," Fournier said. This led to the skyrocketing of carbon dioxide levels, warming of the planet, acidifying of oceans, and poisoning of air. The population of methane-producing bacteria came down after about 100,000 years; however, by that time, the life forms had already undergone a lot of damage. It took around 30 million years for life diversity to recuperate on Earth.