Neila Gross

Chemical and Biomolecular Engineering

Faculty Advisors: Albert Cerrone / Robert Nerenberg

Winter 2020-21 Project: Understanding the Effects of Sonication on Biofilm Removal

Biofilms are the most common form of microbial growth, and a major problem in many engineered systems.  For example, biofilms can foul water filtration systems, increasing energy demands.  They also can coat pipelines and ship hulls, increasing the hydraulic drag.  Most biofilm removal approaches are ineffective, expensive, or not “green.”  New, more effective biofilm management approaches could greatly decrease power demands. The proposed research investigates sonication as a “green” approach to removing biofilms.  Sonication can be applied non-invasively, requires little energy, and does not require harmful chemicals.  Sonication has been shown to kill cells in some studies, and to weaken the biofilm matrix of extracellular polymers (EPS) in others, leading to detachment.  The lack of a basic understanding of the mechanisms of sonication on biofilm removal hinders its effective use.  In this research, the effects of different types of sonication will be systematically investigated.  In particular, the effects of sonication on cell viability and viscoelastic behavior of biofilms will be studied. 

Several biofilm cultures of the same species (e.g. Pseudomonas aeruginosa) will be subjected to different frequencies, power, and duration of ultrasound.  These cultures will then be tested mechanically and for cell viability.  Specifically, shear rheometry in the ND Energy Materials Characterization Facility (MCF) will be used to measure the biofilm viscosity and shear modulus before and after sonication.  The MCF’s atomic force microscope may also be used to quantify stress-strain response.  Additionally, EPS staining chemicals will be used to visualize key EPS constituents (e.g., proteins, lipids, polysaccharides, and DNA) and potentially identify / quantify their degradation.  Mechanical properties will then be correlated to the regimen of sonication (viz. frequency, power, time).  The results of this study could lead to new, more effective strategies to manage biofilm fouling.