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George A. O'Toole, Ph.D.

Professor of Microbiology and Immunology

Microbiology and Immunology

University of Wisconsin - Madison, Ph.D., 1994
Cornell University, B.S., 1988

After postdoctoral work at the University of Wisconsin-Madison and Harvard Medical School, Dr. O'Toole joined the faculty of the Department of Microbiology at Dartmouth Medical School in 1999

Immunology Program
Molecular and Cellular Biology Graduate Programs
Molecular Pathogenesis Program


Contact Information:

Dartmouth Medical School
Vail Building - HB 7550
Hanover NH 03755

Phone: 603-650-1248
Fax: 603-650-1318
Email: George.A.Otoole@Dartmouth.Edu

Professional Interests:

The main focus of the O’Toole laboratory is the study of complex surface-attached bacterial communities known as biofilms. Biofilms can form on a wide variety of surfaces including catheter lines, surgical implants, contact lenses, the lungs of patients with cystic fibrosis, industrial and drinking water pipelines, and on the surfaces of plant roots. In most natural, clinical, and industrial settings bacteria live predominantly in biofilms and not as planktonic (free-swimming) cells such as those typically studied in the laboratory. Bacteria growing in biofilm communities are of great interest to the medical community, because these bacteria become highly resistant to antibiotics by an as yet unknown mechanism. Although much has been learned about the types of microbes that can form biofilms, the morphology of these communities, and their chemical/physical properties, until recently little was known about the molecular genetic basis of biofilm formation or antibiotic resistance.

Studies in the O’Toole lab focus on:
• The molecular genetic basis of biofilm formation.
• The role of the intracellular signaling molecule c-di-GMP in controlling biofilm formation by pseudomonads.
• The signal transduction pathways regulating biofilm formation.
• The mechanisms by which biofilms form on biotic, or living surfaces, and why these biofilms are so highly resistant to antibiotics. We have developed a novel model system for studying biofilms on airway epithelial cells, and these studies are done, in particular, in the context of cystic fibrosis.
• The role of lysogenic phages in impacting biofilm formation.

Recent collaborative studies with Dr. Bruce Stanton’s group here at Dartmouth have explored questions of host-pathogen interactions, using the interplay between the bacterial pathogen Pseudomonas aeruginosa and airway epithelial cells as a model system. We are particularly interested in the role of the toxin, Cif, in altering epithelial cell biology and protein trafficking. We are also studying mechanisms by which P. aeruginosa delivers toxins to host cells.

Please visit the O'Toole Lab Home Page.

Selected Publications:


c-di-GMP and its Effects on Biofilm Formation and Dispersion: a Pseudomonas Aeruginosa Review.
Ha DG, O'Toole GA
Microbiol Spectr. 2015 Apr;3(2):MB-0003-2014. doi: 10.1128/microbiolspec.MB-0003-2014.
PMID: 26104694

Cyclic di-GMP-regulated periplasmic proteolysis of a Pseudomonas aeruginosa type Vb secretion system substrate.
Cooley RB, Smith TJ, Leung W, Tierney V, Borlee BR, O'Toole GA, Sondermann H
J Bacteriol. 2015 Jun 22; pii: JB.00369-15. Epub 2015 Jun 22.
PMID: 26100041

Haemophilus influenzae responds to glucocorticoids used in asthma therapy by modulation of biofilm formation and antibiotic resistance.
Earl CS, Keong TW, An SQ, Murdoch S, McCarthy Y, Garmendia J, Ward J, Dow JM, Yang L, O'Toole GA, Ryan RP
EMBO Mol Med. 2015 May 20;7(8):1018-33. doi: 10.15252/emmm.201505088. Epub 2015 May 20.
PMID: 25995336

Clustered Regularly Interspaced Short Palindromic Repeat-Dependent, Biofilm-Specific Death of Pseudomonas aeruginosa Mediated by Increased Expression of Phage-Related Genes.
Heussler GE, Cady KC, Koeppen K, Bhuju S, Stanton BA, O'Toole GA
MBio. 2015 May 12;6(3):e00129-15. doi: 10.1128/mBio.00129-15. Epub 2015 May 12.
PMID: 25968642

Coculture of Staphylococcus aureus with Pseudomonas aeruginosa Drives S. aureus towards Fermentative Metabolism and Reduced Viability in a Cystic Fibrosis Model.
Filkins LM, Graber JA, Olson DG, Dolben EL, Lynd LR, Bhuju S, O'Toole GA
J Bacteriol. 2015 Jul;197(14):2252-64. doi: 10.1128/JB.00059-15. Epub 2015 Apr 27.
PMID: 25917910

Associations between Gut Microbial Colonization in Early Life and Respiratory Outcomes in Cystic Fibrosis.
Hoen AG, Li J, Moulton LA, O'Toole GA, Housman ML, Koestler DC, Guill MF, Moore JH, Hibberd PL, Morrison HG, Sogin ML, Karagas MR, Madan JC
J Pediatr. 2015 Jul;167(1):138-47.e1-3. doi: 10.1016/j.jpeds.2015.02.049. Epub 2015 Mar 26.
PMID: 25818499

A hierarchical cascade of second messengers regulates Pseudomonas aeruginosa surface behaviors.
Luo Y, Zhao K, Baker AE, Kuchma SL, Coggan KA, Wolfgang MC, Wong GC, O'Toole GA
MBio. 2015 Jan 27;6(1) pii: e02456-14. doi: 10.1128/mBio.02456-14. Epub 2015 Jan 27.
PMID: 25626906

Characterization and quantification of the fungal microbiome in serial samples from individuals with cystic fibrosis.
Willger SD, Grim SL, Dolben EL, Shipunova A, Hampton TH, Morrison HG, Filkins LM, O'Toole GA, Moulton LA, Ashare A, Sogin ML, Hogan DA
Microbiome. 2014;2:40. doi: 10.1186/2049-2618-2-40. Epub 2014 Nov 3.
PMID: 25408892

Surface attachment induces Pseudomonas aeruginosa virulence.
Siryaporn A, Kuchma SL, O'Toole GA, Gitai Z
Proc Natl Acad Sci U S A. 2014 Nov 25;111(47):16860-5. doi: 10.1073/pnas.1415712111. Epub 2014 Nov 10.
PMID: 25385640

Cyclic di-GMP-mediated repression of swarming motility by Pseudomonas aeruginosa PA14 requires the MotAB stator.
Kuchma SL, Delalez NJ, Filkins LM, Snavely EA, Armitage JP, O'Toole GA
J Bacteriol. 2015 Feb;197(3):420-30. doi: 10.1128/JB.02130-14. Epub 2014 Oct 27.
PMID: 25349157