Science: Bacteria vs. antibiotic resistance genes in wastewater

Bacteria engineered to destroy DNA can remove more than 99 percent of the genes that confer antibiotic resistance from wastewater. Treating wastewater in this way could help slow the spread of antibiotic resistance. The innovative approach is proposed by a group of researchers from Michigan State University in a study published in the journal Nature Water. Pathogenic bacteria can absorb resistance genes released into the environment by damaged or dead bacteria. That makes wastewater one of the largest environmental reservoirs of antibiotic resistance genes. Infected microbes can spread to people through water, food, or livestock. In the new study, led by scientist James Tighe, the researchers developed a new way to remove these dangerous genes from wastewater: genetically modifying the bacterium Shewanella oneidensis to produce several enzymes that break the bonds in free-floating strands of DNA. “It chops them up into small pieces, so they can’t be passed on to other organisms,” Tighe says. They chose this bacterium in part because it’s common around the world, “so it’s not something new to add to the environment,” he says. The scientists tested the microbes’ genetic destruction capabilities in wastewater samples collected at different stages of treatment. After 4 hours, the engineered microbes had destroyed more than 99.9 percent of the genetic material in the samples, and after 6 hours, all antibiotic-resistance genes were destroyed. This suggests that wastewater treatment plants could use these genetically modified bacteria to slow the spread of antimicrobial resistance. The microbes produce no byproducts and can be grown easily and cheaply in parts of the world without access to high-tech equipment. (AGI)