Download Studying Bacterial Biofilm Formation

Studying Bacterial Biofilm Formation using Biological Surfaces and Varying Temperatures.
It is estimated that over 80% of bacteria do not exist as single free-living organisms, but reside as multicellular communities known as biofilms. A biofilm is a group of cells attached to a surface surrounded by
a self-produced extracellular polymeric substance (EPS) composed of proteins, nucleic acids, sugars,
and lipids. The EPS provides a physical barrier for the bacterial community, protecting it from a number of
harsh elements such as shear force, antibiotics, and host immune factors. Biofilms play a major role in
human infections and disease, where they can form on skin and tissues within the body as well as
artificial surfaces such as medical implants and devices. Because bacteria within biofilms surround
themselves with an extracellular protective layer, biofilms are difficult to treat even with conventional
antibiotics. The conversion of planktonic (free-living) cells into the biofilm state is not completely
understood and varies between bacterial species. The paradigm for studying biofilm formation within the
laboratory is to grow bacteria on artificial surfaces at body temperature (37°C) and visually observe them
using fluorescently labeled cells and confocal laser scanning microscopy. In the Goodman laboratory we
are interested in a number of bacterial species that cause a variety of different diseases and whose
pathogenic life style is often associated with the biofilm state. Specifically we are interested in the major
human pathogens Streptococcus mutans, Streptococcus pyogenes, and Uropathogenic Escherichia coli.
These organisms are found within different niches of the body such as the oral cavity, the nasopharynx as
well as the skin, and the urinary tract respectively. Because these bacteria are found at different sites
within the body, the surface and temperature at which these bacteria are exposed can vary (i.e. the oral
cavity is at 37°C, the nasopharynx is around 34°C, and the skin is around 30°C). To better understand the
impact temperature and varying surfaces have on biofilm formation, we will test biofilm development using
different biological surfaces (fixed bacterial and tissue culture cells) as well as varying temperatures.
Bacterial biofilms will be measured using conventional stains and confocal microscopy. Our long term
goals are to better understand biofilm formation and to discover new therapeutics that could potentially be
used to treat bacterial infections and disease.
In vitro competition assay of L. reuteri vs. common human pathogens
The probiotic Lactobacillus reuteri has shown a capacity to reduce established Citrobacter rodentium (a
mouse enteric pathogen, very closely related to E. coli) biofilms in vitro. In vivo C. rodentium is used in
place of E. coli due to the latter’s inability to effectively infect mice. However, the ultimate goal of studying
L. reuteri is the optimization of its capacity to prevent and treat human infection, so this work will involve
pitting L. reuteri against common human pathogens in vitro. While there has been ample work done
showing L. reuteri can inhibit the growth of many prokaryotes and eukaryotes, this has largely relied on L.
reuteri’s production of the antimicrobial compound reuterin, and not helping L. reuteri to thrive in the body.
We hypothesize that L. reuteri grown in a biofilm state will increase its capacity to adhere and survive in
the body, and thus increase its ability to inhibit pathogens. Along those lines, the biofilm state can be
made more robust with the addition prebiofilmics; extracellular biofilm structural components that are
limiting in the biofilm, such as DNA and DNA-binding proteins. In addition, we have synthesized
biodegradable copolymer microspheres that can serve as a surface for biofilm growth and a vessel for
prebiofilmics. Taken together, this novel approach will be tested against common human pathogens such
as enteropathogenic E. coli (EPEC), uropathogenic E. coli (UPEC), and Salmonella enterica, and
compared against the more traditional non-optimized approach.
Contact Information
PI Goodman, Steven Center for Microbial Pathogenesis
Steven D. Goodman Ph.D.
Associate Professor of Pediatrics
Center for Microbial Pathogenesis
The Research Institute at Nationwide Children's Hospital
The Ohio State University College of Medicine
700 Children's Drive, W492
Columbus, OH 43205
(614) 355-2761
http://www.nationwidechildrens.org/steven-d-goodman
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