Can Biofilm Engineering Be Used to Address Microplastics Pollution?

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Microplastics, which are fragments of plastic smaller than 5 millimeters, have increasingly been released into the environment over the last several decades—primarily into bodies of water—whether during production, use, or degradation of plastic products. Microplastics have been found in over one hundred aquatic species, in sources of food such as crops, and within large plastic debris piles floating across the ocean. The prevalence of microplastics pollution across ecosystems, exacerbated by the fact that microplastics are not easy to biodegrade, has prompted proposals and passage of legislation in various countries over the past several years, but a more durable solution is needed to address the prevalence of microplastics in our nation’s waterways.

At the Microbiology Society’s annual conference late last month, in April 2021, a team of researchers from Hong Kong Polytechnic University (HKPU) presented initial findings demonstrating a potentially groundbreaking and sustainable method of removing polluting microplastics from the world’s oceans and waterways. Using the natural tendency of bacteria to adhere together and stick to surfaces, thereby creating a sticky substance referred to as “biofilm,” the HKPU researchers proposed using biofilm in the form of a sticky microbial net that would capture microplastics in polluted waterways, collecting the microplastics into a single mass that can then be easily disposed or recycled.

In their preliminary proof-of-concept test, HKPU researchers used bacteria to engineer a biofilm capable of trapping tiny microplastics polluting a body of water. Once the nets incorporated microplastics into themselves, the nets sunk to the floor of the water.  Finally, activating a biofilm-dispersal gene, the HKPU researchers released the collected microplastics from the biofilm trap, in a condition ready for recycling. Notably, the proof-of-concept test was carried out in a controlled laboratory environment rather than in actually polluted oceans, lakes, or rivers. Moreover, the type of bacteria used, Pseudomonas Aeruginosa, likely could not be used in a large-scale project since it typically functions as a disease-carrying bacteria in humans. The HKPU researchers, however, are sure that their proposed method can be adapted for real-world scenarios by finding natural biofilm-forming bacteria within polluted water environments themselves. 

Despite this need for more research concerning the types of surfaces on which biofilm can best grow in order to create real-life biofilm nets, however, the preliminary research provides a promising and exciting vehicle by which microbial technology can assist in reducing now-ubiquitous and ever-increasing microplastics pollution.