Morgan Russell Alexander oral presentation (OB3-Wed2-1-1)
Why do bacteria stick to some surfaces and not others? The role of surface biomolecules
Division of Advanced Materials and Healthcare Technologies, Park Campus, NG7 2RD Nottingham, United Kingdom
Tackling medical device centred infection is an important part of meeting the challenge of antimicrobial resistance. High throughput screening has been used to discover a novel class of polymers with resistance to bacterial attachment and subsequent biofilm formation. [Hook et al. Nat.Biotech. 2012, Adv.Mats. 2013] Physicochemical descriptions of the surfaces have been found insufficient to predict the wide range of bacterial attachment across these diverse polymer libraries, and therefore cannot offer an explanation of the controlling phenomena. Whilst perhaps disappointing for the physical sciences, the life sciences are replete with information on how bacteria respond to their local environment, with motility being one of the most readily observed processes. Microorganisms cannot be approximated to inert objects as they possess surface responsive appendages such as flagella, which enable them to swim, pili that confer twitching motility and fimbriae that mediate surface attachment. These in turn are coupled to sophisticated signal transduction mechanisms that facilitate integration of multiple local environmental parameters at both single cell and population levels. Many of these sensory systems are postulated to contribute to surface sensing. As an example of the complexity of these processes, the opportunistic pathogen Pseudomonas aeruginosa has over 60 two-component sensor kinase response regulator systems involved in environmental adaptation.
We believe that bacterial decision-making is key to determining whether a surface is colonised or not-specifically in the early stages of bacterial-surface interactions preceding biofilm formation. I will present the early results from our optical microscopy investigations of how individual bacterial cells respond to surfaces using a novel microscope that collects temporal 3D information on cell position and surface tracking simultaneously achieved using DIC, TIRF and TIR microscopy. I will combine this information with our early efforts to characterise bacterial footprints and compare with literature that P. aeruginosa for example where the exopolysaccharide Psl guides surface exploration [Zhao et al Nature 2013]. Elucidation of the sensory pathways by which bacteria avoid attaching to resistant polymer surfaces is expected to have wide ranging impact in all areas where biofilms form.