Near-Infrared Light Powers Photosynthesis in Cave Microbes

Microbes discovered in a New Mexico cave system are photosynthesizing using invisible near-infrared light, as reported by the BBC.

A Deep Discovery in Carlsbad Caverns

In 2018, Hazel Barton, a professor of geological sciences at the University of Alabama, and Lars Behrendt, a microbial biologist at Uppsala University, embarked on an exploration of the Carlsbad Caverns. Deep within an alcove, they observed bright green cyanobacteria thriving on cave walls without any visible light.

These remarkable organisms utilize rare chlorophyll d and f, specialized pigments that absorb near-infrared light, which is undetectable by human eyes. The limestone surfaces within the cave play a crucial role, reflecting this invisible light and directing it deep underground to the waiting microbes.

Abundant Invisible Light Fuels Growth

The research team meticulously measured near-infrared concentrations in the most visibly light-devoid sections of the cave. They found these concentrations to be an astonishing 695 times greater than at the cave's mouth. Notably, the largest cyanobacteria colonies were precisely located in these remote, light-rich sections.

Further investigations across other caves within Carlsbad Caverns National Park reinforced the discovery, revealing light-harvesting cyanobacteria in every location sampled.

Implications for the Search for Extraterrestrial Life

This groundbreaking discovery could profoundly alter scientific approaches to finding life beyond Earth. It holds particular relevance for planets orbiting red dwarf stars, which are highly common in the Milky Way and primarily emit near-infrared light.

Barton and Behrendt have since proposed a NASA project aiming to determine the minimum light levels required for these unique organisms' survival. This crucial data could significantly help focus the search for life-supporting planets using the advanced capabilities of the James Webb Space Telescope.

"We showed that not only do they live down there, but that they photosynthesize in a completely sheltered environment where they've probably been untouched for 49 million years."
— Lars Behrendt, Microbial Biologist

"Finding oxygen in the atmosphere of exoplanets is a strong indicator for potential life, as there are very few non-biological ways for oxygen to be produced in an atmosphere."
— Hazel Barton, Professor of Geological Sciences