ASU-led study finds bacteria tap unexpected carbon source

Research reveals a more complex role for microbes in the carbon cycle — and could broaden the search for life beyond Earth

Most of us learn a simple story about carbon: Plants and other photosynthesizers pull carbon dioxide from the air to make their own organic carbon, while animals, fungi and many bacteria must consume organic carbon directly.

A new Arizona State University-led study suggests that bacteria may play a more complex role in carbon cycling than previously thought, challenging this familiar account of carbon flows from plants to animals and bacteria.

An interdisciplinary team of researchers found that two well-studied heterotrophic bacteria — one from soil and one from the sea — used inorganic carbon to build their cells under every laboratory condition tested. Heterotrophic bacteria are generally understood to get their carbon by consuming organic matter. The amount of inorganic carbon they used varied slightly with temperature, food availability and growth stage, highlighting how environmental conditions may influence the process and raising questions about its role in nature. The findings were recently published in Applied and Environmental Microbiology.

“We know that heterotrophic bacteria can use inorganic carbon, but we know less about why they do it, how much they use, or what controls this process. We wanted to take the bacteria into the lab and figure out why they do this,” said lead author Emma Brown, graduate student in ASU’s School of Earth and Space Exploration.

The process is called heterotrophic inorganic carbon fixation, or HICF. Unlike plants, these bacteria still rely on organic carbon for growth. But they can also use dissolved inorganic carbon, such as bicarbonate, to help build cellular material.

That matters because heterotrophic microorganisms are everywhere. They live in soils, oceans, sediments and subsurface environments, where they help transform, store and recycle carbon. If scientists overlook their ability to use inorganic carbon, they may miss part of how carbon moves through ecosystems.

Read the full article on news.asu.edu

Image Credit: ASU

Author Credit: Kim Baptista

Original Post Date: 9.28.26