Researchers at Harvard Medical School in Boston and at Harvard University in Cambridge, Mass., have cultured hundreds of soil bacteria that can subsist on antibiotics alone as their source of carbon nutrition. The scientists tested the bacteria’s ability to consume natural and synthetic antibiotics. They cultured bacteria isolates from 11 soils that could use one of 18 antibiotics as their sole carbon source, and six of the 18 antibiotics supported growth in all 11 soils. These findings reveal that there may be unknown antibiotic-resistance mechanisms from which pathogenic bacteria could draw. The research appears in the April 4 issue of Science. Each image shows a type of bacteria that the researchers found could survive on an antibiotic. The images were modified to improve contrast and color tones.