Hungry bacteria could rid us of our antibiotic waste

Researchers have engineered bacteria that eat antibiotics–which could transform these microbes into a major tool for fighting antibiotic resistance that today plagues public health. If we were one day to release these voracious, genetically-modified microbes into the environment, the researchers believe they could clean soil and water that’s contaminated with antibiotics, leached into the environment from farms and pharmaceutical plants.

We’ve known for some time that certain bacteria eat antibiotics (after all, it’s just another source of carbon to them) but why and how this happened had been a mystery. Through a series of experiments, the researchers–writing in Nature Chemical Biology–identified a set of genes that become active when known antibiotic-munching bacteria dined on penicillin–an outmoded antibiotic–in a petri dish. When strains of common E.coli bacteria were then engineered to contain these same genetic traits, those bacteria could also successfully survive on a diet of pure penicillin.

By understanding the precise genetic makeup behind this ability, the researchers believe that in the future we could employ these engineered bacteria to cleanup antibiotic-contaminated sites. Theoretically, unleashing millions of these hungry microorganisms on infected water and soil could reduce the antibiotic load, which would then reduce the chances of antibiotic resistance spreading between bacteria in the first place. Ultimately we hope that we may be able to use our findings to curb one of the chief causes of antibiotic resistance: contamination of land and water,” the researchers write.

Originally designed as life-saving drugs, major doubts have been cast over antibiotics because their over-application has triggered resistance in the very bacteria they’re supposed to fight. The problem isn’t just confined to hospitals or antibiotics-manufacturing plants: farming is also a major culprit, because livestock in some countries are routinely fed a diet of antibiotics to reduce their chances of developing infections and disease. That’s led to vast amounts of antibiotics being deposited into the water and soil, which seeds resistance in the bacteria that live there. 

Over time this has built up an army of superbugs that pose a serious threat if they reach healthcare facilities, where they may render antibiotics useless. In the US alone, antibiotic resistance already causes 20,000 deaths a year. But this new discovery could be used as a tool to reduce that risk.

To consume an antibiotic, bacteria first have to neutralise it by snipping off a certain portion, which makes it safe to gobble up the rest. In their experiments, the researchers discovered that there were different groups of genes in antibiotic-munching bacteria that controlled particular enzymes which are crucial for this breakdown to occur. By mapping out the intricacies of this process for the first time, the researchers have opened up the possibility that we could manipulate bacteria and turn them into tools for our benefit.

That doesn’t mean we’ll be unleashing armies of engineered bacteria on the environment anytime soon: the researchers caution that genetically modified bacteria may come with their own risks that first need to be ruled out. But with more research and engineering, bacteria could one day become our most useful–and unexpected–ally in tackling this global threat.

Source: Crofts et. al. “Shared strategies for β-lactam catabolism in the soil microbiome.” Nature Chemical Biology. 2018.
Image: Giphy

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