Bacteria engineered to destroy DNA can remove more than 99 per cent of genes that confer antibiotic resistance from wastewater. Treating wastewater with this method could help slow the spread of antibiotic resistance.
Disease-causing bacteria can absorb resistance genes that damaged or dead bacteria have released into the environment. This makes wastewater one of the largest environmental reservoirs for antibiotic resistance genes, says at Michigan State University. Affected microbes can spread to people through water, food or livestock.
Tiedje and his colleagues developed a novel approach to remove these dangerous genes from wastewater: genetically engineering the bacterium Shewanella oneidensis to churn out lots of enzymes that break bonds in free-floating DNA strands. 鈥淚t just basically chops it up into pieces, so it is no longer able to be transferred to other organisms,鈥� says Tiedje. They chose this bacterium partly because it is commonly found throughout the world, 鈥渟o it isn鈥檛 something new we are adding to the environment鈥�, he says.
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They tested the microbe鈥檚 gene-destroying abilities in wastewater samples collected at different stages of treatment. After 4 hours, the engineered microbes destroyed more than 99.9 per cent of genetic material in the samples, and after 6 hours, all of the antibiotic resistance genes were destroyed. This suggests that wastewater treatment facilities could wield this genetically engineered bacterium to slow the spread of antimicrobial resistance.
Current strategies for removing genetic material from wastewater aren鈥檛 widely adopted because they are costly and can come with environmental trade-offs, says at the Center for Global Development in London. For instance, chemical disinfectants like chlorine produce harmful by-products that can end up in nearby waterways, and ultraviolet radiation is energy-intensive. Genetically modified microbes are a promising alternative, he says.
These microbes produce no by-products and can be easily and cheaply grown in areas of the world without access to high-tech equipment, says Tiedje. Right now, it would cost around 拢0.08 to treat a litre of water with this strategy, but Tiedje is confident that the process can be further optimised to cut costs even more.
Nature Water
