A recent study from Imperial College London researchers and published in Nature Communications reveals that gut bacteria use F-pili, an extracellular appendage, to transfer antibiotic-resistant genes. While it was previously believed that harsh conditions inside human and animal guts, such as turbulence, heat, and acids, would break the F-pili, this new research reveals that F-pili structures are actually stronger in these conditions. In fact, the team’s findings found that these conditions helped bacteria transfer resistance genes more efficiently and form biofilms more easily.
Different classes of bacteria use various types of pili to transfer genes during conjugation. For their work, the scientists set out to test this assumption and discovered that agitation increased gene transfer efficiency between bacteria.
They also observed that, after transferring genes, the conjugated bacteria clumped together more easily in shaken conditions to form biofilms that protect inner bacteria from surrounding antibiotic molecules.
F-pili were found to be highly elastic, with spring-like properties that prevented them from breaking when subjected to harsh conditions, including sodium hydroxide, urea, and excessively high temperatures of 100°C.
The team also looked at the F-pili on a molecular level to determine what gave them these unique properties. Ultimately, they were found to be primarily made up of F-pilin subunits with interlinked phospholipid molecules.
While breaking F-pili in pathogenic bacteria might be advantageous, their properties would also be helpful if engineered for drug delivery. Jonasz Patkowski, first author of the study, explains, “Bacteria use [F-pili] to transfer genes, but if we could mimic these properties, we could use similar structures to precisely deliver drugs where they are needed in the body.”
The study’s lead researcher, Dr. Tiago Costa, explained that making F-pili is costly for the bacteria in terms of resources and energy. The challenge now is to find ways to combat this very efficient process. The study’s findings could lead to new methods to interrupt the spread of antimicrobial resistance, and F-pili structures could also be utilized for precise drug delivery in future therapies.