Collaborative Research: Cohesive Strength and Detachment of Bacterial Biofilms

Holzalski, Raymond, PI

University of Minnesota-Twin Cities

CBET-0728550

Stewart, Phillip, PI

Montana State University

CBET-0728621

Collaborative Research: Cohesive Strength and Detachment of Bacterial Biofilms

The goal of this project is to develop effective strategies for controlling and removing microbial biofilms based on an improved understanding of the mechanisms of cohesion of the biofilm extracellular matrix. Biofilms are dense agglomerations of bacterial or fungal cells that attach to wetted surfaces. These cells are held together by a mixture of highly hydrated biopolymers that the cells themselves secrete. Biofilms are responsible for troublesome fouling in water distribution systems, industrial equipment and persistent infections in medicine and dentistry. This project shifts the approach to controlling unwanted biofilms from killing microorganisms with antimicrobial agents to weakening the biofilm structure and promoting detachment. A key to this strategy is to directly measure the cohesive strength of biofilms and relate strength to detachment. Specific objectives of this project are to: (1) investigate mechanisms responsible for biofilm cohesive strength and detachment, (2) evaluate the effect of environmental conditions on strength and detachment, and (3) measure the effects of potential disruptor compounds on strength and detachment. The objectives will be addressed experimentally in a combination of single-species and mixed-species biofilms. A central technique is a micro-cantilever method for pulling on a piece of biofilm and quantifying its mechanical properties. Other methods include time-lapse imaging of biofilm structures in glass capillary reactors under continuous-flow conditions by light microscopy and confocal scanning laser microscopy and measurements of biofilm detachment in rotating disk reactors.

The research will impact engineering through the development of methods to control biofouling, such as in pipelines, where decreased biofilm accumulation could improve the safety of water supplies and reduce energy losses. In terms of public health, this research will provide alternative methods for fighting bacterial infections, such as those encountered on medical implant devices or in the lungs of cystic fibrosis patients, to reduce the need for redundant surgeries and improve/extend life. Graduate and undergraduate students from both institutions will participate in the research. Both groups of students will be afforded opportunities to interact with industry and to present to industrial associates of the Center for Biofilm Engineering at the biannual conference hosted by the center.