Polymer-Induced Biofilms for Enhanced Biocatalysis

The intrinsic resilience of biofilms to environmental conditions makes them an attractive plat-form for biocatalysis, bioremediation, agriculture or consumer health. However, one of the main challenges in these areas is that beneficial bacteria are not necessarily good at biofilm formation. Currently, this problem is solved by genetic engineering or experimental evolution, techniques that can be costly and time consuming, require expertise in molecular biology and/or microbiolo-gy and, more importantly, are not suitable for all types of microorganisms or applications. Here we show that synthetic polymers can be used as an alternative, working as simple additives to nucleate the formation of biofilms. Using MC4100, a strain of Escherichia coli that forms bio-films poorly, we demonstrate that hydrophobic polymers induce clustering and promote biofilm formation in this bacterium, with increasingly hydrophobic polymers outperforming less hydro-phobic polymers. Moreover, we compare the effect of the polymers on MC4100 against PHL644, an E. coli strain that forms biofilms well due to a single point mutation which increases expres-sion of the adhesin curli. In the presence of selected polymers MC4100 can reach levels of bio-mass production and curli expression similar or higher than PHL644, demonstrating that syn-thetic polymers promote similar changes in microbial physiology than those introduced following genetic modification. Finally, we demonstrate that these polymers can be used to improve the performance of MC4100 biofilms in the biocatalytic transformation of 5-fluoroindole into 5-fluorotryptophan. Our results show that incubation with these synthetic polymers helps MC4100 match and even outperform PHL644 in this biotransformation, demonstrating that synthetic polymers can underpin the development of beneficial applications of biofilms.