Scientists from the University of Birmingham have identified synthetic polymers that encourage beneficial bacteria to form biofilms, thereby improving their biocatalytic activity. Given that many beneficial bacteria do not form biofilms naturally, these polymers could be used as simple, inexpensive additives to microbial cultures to encourage their growth.

“To the best of our knowledge, currently there are no methods that provide this simplicity and versatility when promoting biofilms for beneficial bacteria,” said Paco Fernandez-Trillo, PhD, who led the study, which was published in Materials Horizons (“Polymer-Induced Biofilms for Enhanced Biocatalysis”). Fernandez-Trillo is now at the Universidade da Coruña in Spain.

“These synthetic polymers may bypass the need to introduce the traits for biofilm formation through gene editing, which is costly, time-consuming, non-reversible, and requires a skilled person in microbiology to implement it,” he continued.

Biofilms are communities of microorganisms with high cell densities, a situation that provides individuals with protection and allows them to grow more productively. Numerous biofilms are involved in human health and disease, and the biocatalytic properties of biofilms have been exploited to make products such as pharmaceuticals and food ingredients that are not possible by chemical synthesis.

“One of the challenges in exploiting beneficial biofilms for biotechnology or health is that some of the candidate microorganisms, such as probiotics or non-pathogenic strains of Escherichia coli, are not necessarily good at forming biofilms,” the researchers wrote.

Because the formation of biofilms can be influenced by environmental factors such as pH and temperature, the researchers postulated that the chemical properties of synthetic polymers might also play a role.

The researchers screened a library of synthetic polymers with different chemical moieties (mildly cationic, aromatic, heteroaromatic, or aliphatic) for their ability to induce biofilm formation in E. coli. They used a strain of E. coli that is widely used in basic science and is known to be poor at forming biofilms (MC4100).

This screening revealed that the hydrophobic polymers—particularly those with aromatic or heteroaromatic moieties—were best suited to stimulating biofilm formation.

They then compared the effect of the polymers on the growth of MC4100 with that of another E. coli strain that is a good biofilm former (PHL644). The researchers found that MC4100 matched and even outperformed PHL644 in terms of biomass production and curli activity—key phenotypes of biofilm formation.

Lastly, they demonstrated that these polymers can be used to improve the performance of MC4100 biofilms in a biocatalytic reaction. “We believe the presented work significantly advances the state-of-the-art, providing a new methodology to induce biofilms for biocatalysis,” they wrote.

“Moreover, we believe this work has an impact beyond biocatalysis, and should be of relevance to others investigating beneficial applications of biofilms,” they added. “A similar strategy could be employed to induce biofilms in other microorganisms such as probiotics or yeasts, and develop new applications in food science, agriculture, bioremediation, or health.”