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"Our laboratory is interested in understanding the mechanisms by which
bacteria form biofilms on surfaces and obtain nutrients, particularly
iron, in natural and medical environments. We are also interested in
exploring the effects nanoparticles have in the physiology of bacteria
isolated from soil and clinical samples. These studies should provide
a better comprehension of the interactions of bacterial cells with the
extracellular milieu."
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Description of Research
Nanoparticles are more reactive and often possess novel properties that
differ from that of the bulk material due, in large part, to a
relatively higher surface-to-mass ratio. As interest in nanoparticles
has increased, so have concerns that these structures may exert toxic
effects on living systems.
Concerns over tissue penetration have been a dominating topic in the
studies of the effects of nanoparticles in humans. A decrease in
mitochondrial activity was found in cells exposed to a low
concentration of Ag nanoparticles. Similarly, studies have reported
bactericidal effects of MgO, ZnO, and CaO nanoparticles on Escherichia
coli, Staphylococcus aureus, and various Bacillus species. However,
the toxicity of nanoparticles seems to depend on the their size and the
method used for their preparation. It was also shown that Al2O3 and
SiO2 nanoparticles affixed to glass enhance bacterial biofilm
formation. While the specific interactions of nanoparticles with
living systems is not known, it is clear that the problem of studying
nanoparticle effects on cells is complex.
Our laboratory is exploring the interactions of magnetite and
ferrihydrite nanoparticles with two species of Acinetobacter,
ubiquitous bacteria that grow on a diverse range of carbon and energy
sources. FOr this work we chose Acinetobacter baumannii 19606, which
represents clinical isolates that cause severe human infections, and
Acinetobacter ADP1, a naturally transformable soil isolate that could
be used for bioremediation. These studies should provide novel
insights on the interactions of nanoparticles and their effects on
living systems using tractable and relevant experimental models.
Undergraduate researcher's roles in your lab
Undergraduate students work together with graduate students on research
projects they use to earn credit for Independent Study. This is an
excellent opportunity for undergraduate students to experience hands-on
research and participate in meeting presentations and the preparation
of scientific publications.
Graduate student's role in your lab
Graduate students develop their master or doctoral dissertations based
on research projects that will most likely make significant
contributions to the field of microbiology. Graduate students work
together with undergraduate students and postdoctoral fellows. These
interaction foster collaborations and fulfill the commitment of our
graduate program to provide education and training in microbiology at
the undergraduate and graduate levels.
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| Presentations |
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| Funding |
$100.000 Grant from the State of Ohio
Nanomaterials in our Environment
$100.000 Grant from the State of Ohio
Nanomaterials in our Environment
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| Publications |
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Tomaras, A. P., C. W. Dorsey, R. E. Edelmann, and L. A. Actis.
Attachment to and biofilm formation on abiotic surfaces by
Acinetobacter baumannii: involvement of a novel chaperone-usher pili
assembly system. Microbiology, 149, 3461-3484, 2003.
Actis, L. A, E. Rhodes, and A. Tomaras. Genetic and molecular
characterization of a dental pathogen using genome-wide approaches.
Advances in Dental Research, 17, 95-99, 2003.
Dorsey, C. W., A. P, Tomaras, P. L. Connerly, M. E. Tolmasky, J. H.
Crosa, and L. A. Actis. The siderophore-mediated iron acquisition
systems of Acinetobacter baumannii ATCC 19606 and Vibrio anguillarum
775 are structurally and functionally related. Microbilogy, 150,
3657-3667, 2004.
McGillivary, G., A. P. Tomaras, E. R. Rhodes, and L. A. Actis. Cloning
and sequencing of a genomic island found in the Brazilian purpuric
fever clone of Haemophilus influenzae biogroup aegyptius. Infect.
Immun. 73, 1927-1938, 2005.
Rhodes, E. R., A. P. Tomaras, G. McGillivary, P. L. Connerly, and L. A.
Actis. Genetic and functional analysis of the Actinobacillus
actinomycetemcomitans AfeABCD siderophore independent iron-acquisition
system. Infect. Immun. 73, 3758-3763, 2005.
McGillivary, G., L. M. Smoot, and L. A. Actis. Characterization of the
IgA1 protease from the Brazilian purpuric fever strain F3031 of
Haemophilus influenzae biogroup aegyptius. FEMS Microbiol. Lett. 250,
229-236, 2005.
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