Unintended Consequences: How Our Waste is Leading to the Evolution of Beneficial Bacteria

Saturday - March 2 2024, 23:29 UTC - 8 months ago

The popular diabetes medication metformin is also being studied for its potential to reduce inflammation, curb cancer, and slow the aging process. However, its widespread use has led to an unintended consequence – it's ending up in our wastewater and potentially affecting aquatic organisms. Researchers have identified the bacteria responsible for metabolizing metformin and are exploring ways to better remove micropollutants from wastewater using bacteria-based technologies.

Metformin, a widely prescribed diabetes medication, has been called a miracle drug for its ability to keep diabetes in check and potentially offer additional health benefits such as reducing inflammation, curbing cancer, and slowing the aging process. It's no surprise, then, that the popularity of metformin has skyrocketed in recent years. In the US alone, the number of prescriptions has more than doubled in less than two decades. But with this increased usage comes a sobering realization – all that metformin doesn't just stay in our bodies, but it also ends up in our wastewater.

The amount of metformin that enters our wastewater is staggering, with over 100 million kilograms consumed worldwide each year. While the levels found in wastewater are not likely to harm humans, they can have negative effects on aquatic organisms who are living in it. This led biochemist Lawrence Wackett of the University of Minnesota to investigate the issue, and in 2022 his team and two others identified the bacteria responsible for metabolizing metformin and sequenced their genomes. But the question remained, which genes were specifically responsible for this process? .

This type of bacterial evolution is not uncommon. In the 1960s, a popular weed killer called atrazine was introduced to farmers. Initially, researchers found that the chemical was degrading slowly in soil. But a decade later, bacteria evolved the ability to metabolize atrazine, turning it into a source of nitrogen. This selective pressure, as Wackett explains, gave these bacteria a big advantage.

What's interesting is that while we often hear about bacteria evolving in ways that are detrimental to human health, they can also evolve in ways that can benefit us. This idea is not just limited to medicines, but also extends to everyday personal care products that end up in our wastewater. These micropollutants, such as shampoos, body washes, and face serums, were never factored into the design of wastewater treatment plants, which were primarily focused on preventing infectious diseases. As a result, traditional methods of wastewater treatment are not very effective at removing these tiny pollutants.

However, certain technologies that rely on bacteria, such as membrane biological reactors and biofilm reactors, show promise in removing pharmaceuticals and other micropollutants from wastewater. These methods combine activated sludge with microfiltration or rely on bacteria grown on the surface of membranes, allowing them to better break down and remove these pollutants. While it may have been an unintended consequence, the evolution of beneficial bacteria in our wastewater could ultimately help solve the problem of micropollutants and protect our environment.