Microscopic life in lava caves and tubes on the Big Island that are hundreds of years old could help understand how life might have existed on early Earth and Mars.
A team of researchers, including experts from the University of Hawaiʻi at Mānoa School of Life Sciences, investigated several sites on Hawaiʻi Island. Samples from bacterial communities the researchers collected revealed that a group of bacteria called Chloroflexi are what researchers refer to as hub species, meaning they are connected to many other species, and usually play key ecological roles in their communities.
“This paper brought together scientists who have worked in Hawaiian lava caves for decades, and it reveals the novelty and complexity of bacterial communities in places most people think of as too hostile for life,” Stuart Donachie, UH-Mānoa professor and a study co-author, said in a press release. “Our results underscore that remarkable microbial diversity and novelty exist in Hawaiʻi. We’re now building on our findings by exploring how bacteria cultivated from these caves function in conditions that mimic those believed to have occurred on Mars, and long ago on Earth.”
The research findings were recently published in Frontiers in Microbiology.
Donachie, and lead author, NASA postdoctoral research fellow and UH-Mānoa microbiology doctorate graduate Rebecca Prescott, along with a diverse team of collaborators, collected 70 samples from Big Island lava tubes and caves of varying age, from younger than 400 years old to between 500 and 800 years old, as well as fumaroles, which are active geothermal vents from where steam and gases emerge in or near a volcano.
Researchers predicted that the fumaroles, where conditions are harshest, would have lower diversity than the older, more habitable lava tubes. While the diversity was lower at the fumaroles, researchers were surprised to discover that interactions in those communities were more complex than in lava tubes with higher diversity.
Further research will investigate if more extreme environments help to create more interactive microbial communities, where microorganisms might be more dependent on each other.
In addition to providing insights about the past, bacteria from volcanic environments can also be useful in understanding how microbes turn volcanic rock into soils, as well as bioremediation, which is how microorganisms break down pollutants in the environment; biotechnology; and sustainable resource management. That could, in turn, provide clues about the nature of life on Mars long ago or even possibly today.