The soil microbe mineral battery stores sunlight to break down antibiotics in the dark
Researchers have discovered how soil communities can store sunlight as usable energy long after nightfall. A team from Kunming University of Science and Technology and the University of Massachusetts Amherst reports a bio-photovoltage soil microbe battery that stores solar charge and later drives the degradation of contaminating antibiotics without light.
In laboratory tests, the common soil bacterium Bacillus megaterium interacted with iron minerals to form a living film that behaves like a rechargeable geochemical capacitor. Under illumination, the iron-bacteria matrix collected electrons; in the dark, the stored charge triggered chemical reactions that broke down tetracycline and chloramphenicol.
“Our findings show that soil microorganisms and minerals can function together as small natural batteries,” said co-corresponding author Professor Bo Pan from 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 up a total accumulated charge of 8.06 microcoulombs per square centimeter over light-dark cycles. After an hour of pre-illumination, the setup removed up to 22 percent of antibiotics in complete darkness, up to 67 percent better than shorter exposure to light.
Electrochemical analyzes revealed an efficient redox relay between Fe(II) and Fe(III), aided by bacterial metabolism, allowing charge storage and gradual release. The mineral-microbe interface improved electron transfer and reduced losses, behaving as a biological pseudocapacitor.
“This discovery opens a new window into how solar energy can drive biogeochemical processes even beneath 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 that similar mineral-microbe power pairs could quietly support energy flow and pollution control in different ecosystems.
Research report:A bio-photovoltage soil microbe battery for the degradation of antibiotics in the dark
