A plant–bacterium system turned wastewater metals into photoactive material

Researchers paired water lettuce with engineered bacteria that grow in the oxygen-rich root zone. The microbes use plant exudates, reduce sulfate and release hydrogen sulfide, precipitating cadmium and lead as cadmium-sulfide and lead-sulfide particles anchored to cells. The resulting semiconductor–cell biohybrids show photoelectric activity, while bacterial auxin helps offset metal stress in the plant. The concept joins capture with material recovery, but remains experimental; scale, safe handling and net energy value still need validation.