Bacterial biofilm is the most abundant form of life on Earth. The understanding and control of the biofilm formation has been a research focus of microbiologists, medical scientists and engineers for the past 20 years mainly due to its roles in biofouling of industrial pipelines, antibiotic resistance, and in chronic infections. On the other hand, industrial wastewater treatment plants and agricultural technologies utilise the benefits of biofilms. The search for new sustainable technologies has led to the fast development of non-conventional materials produced by certain bacteria, such as bacterial cellulose.
The formation of bacterial biofilms on solid surfaces within a fluid starts when bacteria attach to the substrate. Understanding environmental factors affecting the attachment and the early stages of the biofilm development is the key to promoting and discouraging the biofilm growth. We showed that the biofilm formation is strongly affected by the flows in bacterial suspensions. Such flows can be controlled by surface waves . Deterministic wave patterns promote the growth of patterned biofilms while the wave-driven turbulent motion discourages patterned attachment of bacteria. By controlling the wavelength, amplitude, and horizontal mobility of the waves, one can shape the biofilm, and either enhance the growth, or discourage the formation of the biofilm.
Wave-assisted biofilm production has great potential in engineering of new biomaterials, since the wave action is the strongest at the liquid-air interface, where the bacterial cellulose forms. We applied this approach to engineer new cellulose materials whose morphology is controlled by the wave-driven flows. This allowed to create different cellulose forms, such as for example spherical cellulose beads, and planar pellicles which are used in many industrial, scientific and agricultural applications.
: Surface waves control bacterial attachment and formation of biofilms in thin layers. Sung-Ha Hong, Jean-Baptiste Gorce, Horst Punzmann, Nicolas Francois, Michael Shats and Hua Xia. Science Advances, in press (2020).
Dr Hua Xia has been working at the ANU since 2006 on physics of fluids and their applications in atmospheric, oceanic and biological systems. Her research has attracted funding from the ARC including several Discovery projects, a DECRA award (2012-2014) and a Future Fellowship (2015-2018). Dr Xia's current research focus is on the physics approaches to microbiological systems for novel biophysical applications. The work presented here is part of her ARC DP19 project 'Transport control in multi-species fluid suspensions for biomedical applications' (2019-2022).