In lab tests, common soil bacterium Bacillus megaterium partnered with iron minerals to form a living film that behaves like a rechargeable geochemical capacitor. Under illumination, the iron-bacteria matrix accumulated electrons; in darkness, the stored charge powered chemical reactions that degraded tetracycline and chloramphenicol.
"Our findings reveal that soil microorganisms and minerals can together function like tiny natural batteries," said co-corresponding author Professor Bo Pan of Kunming University of Science and Technology. "This system can capture sunlight during the day and use that energy at night to remove pollutants."
The Fe2O3-B. megaterium composite built a total accumulated charge of 8.06 microcoulombs per square centimeter across light-dark cycles. After one hour of prior illumination, the setup removed up to 22 percent of antibiotics in complete darkness, up to 67 percent better than shorter light exposures.
Electrochemical analyses showed an efficient redox relay between Fe(II) and Fe(III), aided by bacterial metabolism, enabling charge storage and gradual release. The mineral-microbe interface improved electron transfer and lowered losses, acting like a biological pseudocapacitor.
"This discovery opens a new window into how solar energy can drive biogeochemical processes even below the soil surface where sunlight cannot reach," said Professor Baoshan Xing of the University of Massachusetts Amherst, a co-corresponding author. "It also suggests an environmentally sustainable way to remediate contaminated soils and groundwater."
The authors suggest similar mineral-microbe power pairs may quietly support energy flow and pollution control across diverse ecosystems.
Research Report:A bio-photovoltage soil-microbe battery for antibiotic degradation in the dark
Related Links
Biochar Editorial Office, Shenyang Agricultural University
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