Isaac Klapper
Department of Mathematical Sciences
Montana State University

Tuesday, April 29, 2008
4:00PM in 127 Hayes-Healy
*Tea at 3:30 in 257 Hurley*

Physical Description of Biofilms

Compared to the plant and animal kingdoms, diversity of microbial life is considerably less explored and less understood (even the notion of microbial species is a current topic of debate. Prokaryotes (bacteria and archaea) are estimated to make up approximately half of extant biomass; for example each human harbors about 100 trillion microbes (bacteria and archaea), ten times more microbial than human cells.
The familar view of microbes in their free (planktonic) state is however not the norm; rather it is believed that much of the microbial biomass, perhaps 95-99%, is located in close-knit communities,
designated biofilms and microbial mats, consisting of large numbers of organisms living within self-secreted matrices constructed of polymers and other molecules. (Microbes in collective behave very differently from their planktonic state; even genetic expression patterns change.) These matrices serve the purposes of anchoring and protecting their communities in favorable locations while providing a framework in which structured populations can differentiate and self-organize.

One can and will find biofilms in almost any damp or wet environment, and they are often key players in areas such as (environmental) biogeochemical cycles, (industrial) fouling of equipment and water systems, and waste remediation, just to name a few. Medical relevance is
especially dramatic. Quoting from the National Institutes of Health: "Biofilms are clinically important, accounting for over 80 percent of microbial infections in the body.  Examples include: infections of the oral soft tissues, teeth and dental implants; middle ear; gastrointestinal tract; urogenital tract; airway/lung tissue; eye; urinary tract prostheses; peritoneal membrane and peritoneal dialysis catheters, in-dwelling catheters for hemodialysis and for chronic administration of chemotherapeutic agents (Hickman catheters); cardiac implants such as pacemakers, prosthetic heart valves, ventricular
assist devices, and synthetic vascular grafts and stents; prostheses, internal fixation devices, percutaneous sutures; and tracheal and ventilator tubing.''

Viewed as materials, biofilms are quite interesting: they are living, growing viscoelastic fluids with surprising ability to respond to and defend against their environments. This talk wlll present
a general overview of efforts to characterize and model biofilms on a continuum macroscale, addressing some of the issues mentioned above.