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Research Interests:
- biofilms in marine processes
- chemical/spectroscopic characterization of EPS
- microbial mats
- bacterial chemical communication
- bioavailability; animal/microbial interactions
- pathogen survival/infections in biofilms
- Nano/environmental processes in biofilms
Bacteria are pivotal components in natural and engineered
systems. “Biofilms” consist of bacterial cells that are embedded
within a matrix of extracellular polymeric secretions (EPS) and
usually attached to a surface.
Figure 1.
Figure 1. A “Biofilm” forms in several steps: (1)
planktonic (individual) bacteria attach to surface; (2)
secrete extracellular polymers (EPS); (3) communicate
with each other, and alter gene expression; and (4)
coordinate activities. The net result is a biofilm that
is “orders of magnitude more Resilient” (able to
survive) than the original planktonic bacteria!
In ocean systems, biofilms form microscopic coatings on virtually
all surfaces. Further, they influence marine snow formation, organic
matter cycling, larval settlement processes, sediment stability, and
the optical properties of sediments. From an environmental
standpoint, biofilms are ‘sorptive sponges’ and important sites for
the binding, transformation and trophic-transfer of contaminants
(and potentially toxic nanoparticles). In health settings, the
biofilm represents a ‘resistant refugia’ for pathogenic
(disease-causing) bacteria. Biofilms are responsible for greater
than 70% of hospital-acquired (nosocomial) infections, drinking
water related outbreaks of disease, and may even play roles in the
initial events of certain cancers. This results in a multi-billion
$$ cost to society, health and industry.
Many biofilms are now known to exhibit a high level of
organization, physical microarchitecture, and extracellular chemical
communication networks. This allows bacterial cells in proximity, to
act as a ‘single group’, and further, allows different microbial
groups within a biofilm to coordinate activities; providing greater
metabolic efficiency and resiliency than would be otherwise
possible. Thus, chemical communication within biofilms likely
contributes to the 1) high-diversity, 2) adaptability and 3)
resiliency of bacteria in both natural systems and hospital-disease
settings.
My research interests center on the role of the ‘extracellular
polymeric matrix (EPS)’ of biofilms in marine, environmental and
health-related processes. We are exploring fundamental biological
and chemical processes that occur within biofilms in order to
understand how they function, and ultimately how they may be
manipulated or controlled. Our laboratory is probing the
microspatial organization, physical and chemical microarchitecture
of EPS, and chemical communication networks of biofilms. We are
using recently-developed molecular investigations, chemical
approaches, and non-destructive spectroscopic and imaging techniques
to investigate biofilms under in-situ and manipulated conditions.
Currently, we are utilizing confocal (CSLM) and multi-photon
(MP-SLM) scanning laser microscopy, environmental scanning (ESEM)
and transmission (TEM) electron microscopy, atomic force microscopy
(AFM), NMR, FT-IR and Raman spectroscopy to probe the extracellular
matrix of both natural biofilms and those from cultured
microorganisms. A second related area of research involves the roles
of biofilms in regulating the bioavailability and trophic-transfer
of metals, pesticides, and nanoparticles in natural environments.
Figure 2. In human-health settings, the biofilm forms a
‘resistant refugia’ for pathogenic (disease-causing) bacteria
against antimicrobial agents. A few examples include their roles in
persistent (polymicrobial), urinary-tract (UTIs), hospital-acquired
(nosocomial) infections; dental plaque formation; and drinking-water
related outbreaks of disease. Biofilms may even play roles in the
initial events of certain cancers. In natural environments, biofilms
act as efficient ‘sorptive sponges’ for the binding trophic-transfer
of contaminants, and colloids, even ‘nanoparticles’. In marine
systems, biofilms and their EPS influence the formation of ‘marine
snow’ in the water column, global carbon cycling, larval settlement
processes, and the physical stability and optical properties of
sediments.
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