New York: pollution-eating microbes thriving in Brooklyn’s Gowanus Canal

For over a century, industrial pollution and urban waste have flowed into Brooklyn’s Gowanus Canal, making it one of the most contaminated waterways in the United States. Though the industries that once lined its banks have disappeared, their toxic legacy remains, with a considerable amount of contaminated sediment at the bottom of the canal today. However, a new study published in the Journal of Applied Microbiology found that microbes in the Gowanus sediment have evolved ways of coping and even subsisting off the contamination. These microbes, including bacteria and viruses, are slowly separating and eating up several chemical compounds in the canal mud. According to the authors of the study, Elizabeth Hénaff (New York University) and Sergios-Orestis Kolokotronis (SUNY Downstate Health Sciences University), they could be used by engineers and biologists to help detoxify the Gowanus and other polluted sites. This process known as bioremediation has already been applied to wastewater treatment and cleaning up oil spills, including the 1989 Exxon Valdez incident in Alaska.
To conduct their research, Hénaff, Kolokotronis, and their colleagues paddled out on the canal and collected sediment samples using a PVC pipe. According to Kolokotronis, it was a challenging and dangerous job, with the research team using full personal protective equipment to minimize contact with potentially harmful substances. Back in the lab, the researchers analyzed the DNA in the samples to identify the microbe species present and their genetic makeup. They found 455 different species, 64 metabolic pathways known to degrade organic contaminants like phenols and toluene, and over 1100 genes related to heavy metal uptake. They also classified thousands of previously un-cataloged gene clusters and metabolites with the potential for breaking down pollutants. According to Max Hӓggblom (Rutgers University), who was not involved in the study, such a rich mixture of microorganisms could be “mined” for all bioremediation projects. Altering the environmental conditions of a waterway with the right mix of nutrients, for example, could boost the population of beneficial bacteria helping its recovery, minimizing costs and disruptions. Sediment dredged up from a contaminated canal might also be rendered less dangerous before landfilling by being purposefully mixed with certain microbes.
However, pollution-eating microorganisms are not enough to fully clean up a contaminated site like the Gowanus, which continues to pose a public health risk for nearby residents. Though breaking down heavy metals, for example, microbes cannot eliminate the toxic elements present in such substances. Therefore, pollutants must first be removed by human hands, potentially employing microorganisms later in the recycling process. For Hénaff, it is “an exciting possibility”, which could help retrieve several substances from the Gowanus and reutilize them for technological and industrial purposes.