Abstract #291

Section: Dairy Foods
Session: Dairy Foods Symposium: Biofilm Formation on Dairy Separation Membranes
Format: Oral
Day/Time: Tuesday 11:00 AM–11:30 AM
Location: 327
Recorded Presentation is being recorded
# 291
Controlling microbial biofilms.
P. S. Stewart*1, 1Montana State University, Bozeman, MT.

This presentation will discuss fundamental physical, chemical, and biological concepts important to understanding control of detrimental biofilms such as those that can foul and contaminate food processing equipment. Three phenomena that are important in the action of antimicrobial agents against a biofilm will be examined: diffusion, hydrodynamics, and physiology. The penetration of a biocide into a biofilm is governed by the balance of reaction and diffusion. Oxidizing agents in particular are subject to retarded or incomplete penetration due to their inactivation within the biofilm. Oxygen and nutrient concentration gradients within biofilms lead to stratified patterns of anabolic activity. For example, microelectrode technology demonstrates the presence of anoxic niches in biofilms exposed to aerated medium. Staining techniques reveal that the same biofilm can harbor, in distinct spatial niches, growing and dormant cells. Variation in the physiological activity is accompanied by alterations in susceptibility to antimicrobials. Time-lapse imaging of biofilms subjected to antimicrobial treatments reveals that in many cases these treatments do not remove the biofilm. In instances where removal is observed it is clear that forces applied by the flowing fluid are an important component of the removal process. The biofilm defense against biocides and antibiotic is multifactorial and so requires integrated and interdisciplinary science.

Key Words: biofilm, biocide, fouling

Speaker Bio
Dr. Stewart is a Professor of Chemical and Biological Engineering at the Center for Biofilm Engineering at Montana State University. He received his B.S. (1982) from Rice University, and M.S. (1985) and Ph.D (1988) degrees from Stanford University, all in chemical engineering. After finishing his doctoral studies, he was a NATO postdoctoral fellow at the Institut Jacques Monod in Paris, France and a senior chemical engineer at Bechtel Environmental in San Francisco, California. He joined the faculty of Chemical Engineering at Montana State in 1991. Dr. Stewart has also been integrally involved with the Center for Biofilm Engineering since his arrival on the Montana State campus, serving as director from 2005-2015. Dr. Stewart’s research focuses on the control of detrimental microbial biofilms. He has authored or co-authored more than 170 technical publications and has directed projects for eighteen industrial sponsors. He is the recipient of an NSF Career Award and has been honored at Montana State University with both of that institution’s top faculty awards for excellence in research and scholarship.