Bacteria are remarkable in that they are able to survive and grow in basically every niche on the planet. They are able to respond and adapt to adverse environmental stressors such as heat or cold, high or low pH, antimicrobials or even the human immune system, by changes in gene expression, ensuring their survival (bacterial stress response). This adaptation process is mainly mediated by a striking combination of transcriptional regulatory networks, which allow bacteria to sense and convert extracellular, physical or chemical stimuli into a specific cellular response, resulting in altered gene expression and enzyme activities (signal transduction). Whereas some of these alterations are reversible and disappear when the stress is over, others are maintained and can even be passed on to surviving bacteria.

 

           

 

 

                                       Bacterial adaptation and stress response networks

 

 

In this KIT research group, we use state of the art molecular biology tools in combination with bioinformatics and a wide range of microscopy techniques to identify and characterize bacterial stress responses in applied and environmental microbiology as well as to elucidate the underlying complex regulatory networks. An understanding of how bacteria adapt to their environment and how certain agents interact with these bacteria can help us to control growth and production rates in biotechnological applications and to enhance bacterial killing with respect to biomedical treatments in the future.

 

One adaptation to stressful conditions exhibited by a wide range of bacteria is the formation of biofilms on surfaces or interfaces. Biofilms are communities of microorganisms attached to a surface and embedded in an extracellular polymeric matrix (EPS). Most bacteria in the environment exist as biofilms and biofilm bacteria have been shown to possess unique characteristics that are not seen in conventional test tube-grown bacteria. It has also been recently estimated that up to 70% of bacterial infections involve biofilm bacteria which are able to persist during chronic infections. Bacteria grown in biofilms exhibit high resistance against antimicrobial agents such as biocides or antibiotics and are protected from protozoan grazing or killing by the human immune response. Biofilm development is a sequential process initiated by the attachment of planktonic cells to a surface, followed by formation of microcolonies and biofilm maturation in which the bacterial community is embedded in a polymeric matrix composed of nucleic acids, proteins, and exopolysaccharides, and finally the dispersal of single cells or cell aggregates from the bulk biofilm.

 A)                                                             B)

 

Bacterial biofilms. A) Burkholderia cenocepacia and B) Pseudomonas aeruginosa

 

We use both model organisms like the human pathogen Pseudomonas aeruginosa as well as environmental and clinical isolates to study molecular mechanism involved in the interaction of bacteria with biotic and abiotic surfaces. In particular, we are interested in how bacteria sense their surrounding environment, how they interact with surfaces and which environmental signals stimulate or prevent adhesion and biofilm formation. Major focus of our research is the identification and characterization of signaling molecules and complex regulatory networks governing this multicellular bacterial behavior.

 

Research Focus

Bacterial stress response in applied and environmental microbiology, biofilm formation

 

Work Experience

Since July 2010

Head of Junior Research Group 'Bacterial Stress Response and Process Engineering', KIT, Karlsruhe, Germany,

2009 – 2010    

Postdoctoral Fellow at the Helmholtz Centre for Infection Research, Braunschweig, Germany

2005 – 2008

Postdoctoral Fellow at the University of British Columbia, Vancouver, Canada

2004

Postdoctoral Fellow at the Massey University, Palmerston North, New Zealand

2003

Postdoctoral Fellow at the Westfälische Wilhelms-University, Münster, Germany

 

Education

1998 - 2003   

PhD in Microbiology at the Westfälische Wilhelms-University, Münster, Germany

1992 - 1998  

Diploma Biology at the Westfälische Wilhelms-University, Münster, Germany

 

 

Stipends and Awards

2004

Alexander von Humboldt Fellowship for research in Canada

2006

Canadian Cystic Fibrosis Fellowship for research in Canada

 

2012

• Breidenstein, E.B.M., L. Janot, J. Strehmel, L. Fernandez, P.K. Taylor,I. Kukavica-Ibrulj, S.L. Gellatly, R.C. Levesque, J. Overhage, and R.E.W. Hancock. 2012. The Lon protease is essential for full virulence in Pseudomonas aeruginosa . PLOS One, in press.

• Breen, E.C., J. L. Malloy, K. Tang, F. Xia, R. E. Hancock, J. Overhage, P. D. Wagner, R. G. Spragg. 2012. Journal of Cellular Physiology. Accepted Article. Doi:10.1002/jcp.24140

• Kahle, N.A., G. Brenner-Weiss, J. Overhage, U . Obst, G.M. Hänsch. 2012. Bacterial quorum sensing molecule induces chemotaxis of human neutrophils via induction of p38 and leukocyte specific protein 1 (LSP1). Immunobiology. In press.

• Zaoui, C., J. Overhage, D. Löns, A. Zimmermann, M. Müsken, P. Bielecki, C: Pustelny, T. Becker, M. Nimtz, S. Häussler. 2012. An orphan sensor kinase controls quinolone signal production via MexT in Pseudomonas aeruginosa. Molecular Microbiology. 83:536-47.

 

 2011

• Adamek, M, J. Overhage, S. Bathe, J. Winter, R. Fischer, T. Schwartz. 2011. Genotyping of environmental and clinical Stenotrophomonas maltophilia isolates and their pathogenic potential. PLoS One. 6:e27615

 

2009

• Yeung A.T.Y., E.C.W. Torfs, F. Jamshidi, M. Bains, I. Wiegand, R.E.W. Hancock, and
   J. Overhage. 2009. Swarming of Pseudomonas aeruginosa is controlled by a complex regulatory network. Journal of Bacteriology. 191:5592-602.

 

2008

• Breidenstein E.B., B.K. Khaira, I. Wiegand, J. Overhage, and R.E.W. Hancock. 2008. Complex ciprofloxacin resistome revealed by screening a Pseudomonas aeruginosa mutant library for altered susceptibility. Antimicrobial Agents and Chemotherapy. 52:4486-91.

• Overhage J.,  A. Campisano, M. Bains, E.C. Torfs, B.H.A. Rehm, and R.E.W. Hancock. 2008. Human host defence peptide LL-37 prevents bacterial biofilm formation. Infection and Immunity. 76:4176-82.

• Blohmke C.J., A.F. Hirschfeld, I. Elias, R.E. Victor, D.G. Hancock, A.G.F. Davidson, P.G. Wilcox, K.D. Smith, J. Overhage, R.E.W. Hancock, and S.E. Turvey. 2008. Innate immunity mediated by TLR5 as a novel anti-inflammatory target for cystic fibrosis lung disease. Journal of Immunology. 180:7764-73.

• Overhage J., M. Bains, M.D. Brazas, and R.E.W. Hancock. 2008. Swarming of Pseudomonas aeruginosa PAO1 is a complex adaptation leading to increased production of virulence factors and antibiotic resistance. Journal of Bacteriology. 190:2671-9.

• Leung B.O., A.P. Hitchcock, J.L. Brash, A. Scholl, A. Doran, P. Henklein, J. Overhage, K. Hilpert, J.D. Hale and R.E.W. Hancock. 2008. An X-ray spectromicroscopy study of competitive adsorption of protein and peptide onto polystyrene-poly(methyl methacrylate). Biointerphases 3 FA27-35.

• Campisano A., J. Overhage, and B.H.A. Rehm. 2008. The polyhydroxyalkanoate biosynthesis genes are differentially regulated in planktonic- and biofilm-grown Pseudomonas aeruginosa. Journal of Biotechnology. 133:442-52.

 

2007

• Brazas M.D., E. Breidenstein, J. Overhage, and R.E.W. Hancock. 2007. Role of Lon protease, an ATP-dependent protease homolog, in resistance of Pseudomonas aeruginosa to ciprofloxacin. Antimicrobial Agents and Chemotherapy. 51:4276-83.

• Stewart-Ornstein J., A.P. Hitchcock, D. Hernàndez-Cruz, P. Henklein, J. Overhage,
  K. Hilpert, J.D. Hale and R.E.W. Hancock. 2007. Using intrinsic X-ray absorption spectral differences to identify and map peptides and proteins. Journal of Physical Chemistry B. 111:7691-9.

• Parschat K., J. Overhage, A. Strittmatter, A. Henne, G. Gottschalk, and S. Fetzner. 2007. Complete nucleotide sequence of the 113 kb linear catabolic plasmid pAL1 of Arthrobacter nitroguajacolicus Rü61a, and transcriptional analysis of genes involved in quinaldine degradation. Journal of Bacteriology. 189:3855-67.

• Overhage J., S. Lewenza, A.K. Marr, and R.E. Hancock. 2007. Identification of Genes Involved in Swarming Motility Using a Pseudomonas aeruginosa PAO1 Mini-Tn5-lux Mutant Library. Journal of Bacteriology. 189:2164-9.

• Marr A.K., J. Overhage, M. Bains, and R.E. Hancock. 2007. The Lon protease of Pseudomonas aeruginosa is induced by aminoglycosides and is involved in biofilm formation and motility. Microbiology. 153:474-82.

 

2006

• Overhage J., A. Steinbüchel and H. Priefert. 2006. Harnessing eugenol as a substrate for production of aromatic compounds with recombinant strains of Amycolatopsis sp. HR167. Journal of Biotechnology. 125:369-76.

• Campisano A., C. Schroeder, M. Schemionek, J. Overhage, and . B.H. Rehm. 2006 PslD is a secreted protein required for biofilm formation by Pseudomonas aeruginosa. Applied and Environmental Microbiology. 72:43066-8.

• Plaggenborg R., J. Overhage, A. Loos, J.A.C. Archer, P. Lessard, A.J. Sinskey,
  A. Steinbüchel and H. Priefert. 2006. Potential of Rhodococcus strains for biotechnological vanillin production from ferulic acid and eugenol. Applied Microbiology and Biotechnology. 72:745-55.

 

2005

• Overhage J., M. Schemionek, J.S. Webb and BH Rehm. 2005. Expression of the psl operon in Pseudomonas aeruginosa PAO1 biofilms: PslA performs an essential function in biofilm formation.  Applied and Environmental Microbiology. 71:4407-13.

•  Overhage J., S. Sielker, S. Homburg, K. Parschat and S. Fetzner. 2005. Identification of large linear plasmids in Arthrobacter spp. encoding the degradation of quinaldine to anthranilate. Microbiology. 151:491-500.

 

1999 - 2003

•  Overhage J., H. Priefert and A. Steinbüchel. 2003. High efficient biotransformation of eugenol to ferulic acid and further to vanillin with recombinant strains of Escherichia coli. Applied and Environmental Microbiology. 69:6569-76.

•  Plaggenborg R., J. Overhage, H. Priefert and A. Steinbüchel. 2003. Functional analyses of genes involved in the metabolism of ferulic acid in Pseudomonas putida  KT2440. Applied Microbiology and Biotechnology. 61:528-35.

•  Overhage J., H. Priefert and A. Steinbüchel. 2002. Biotransformation of eugenol to ferulic acid by a recombinant strain of Ralstonia eutropha H16. Applied and Environmental Microbiology. 68:4315-4321.

• Brandt K., S. Thewes, J. Overhage, H. Priefert and A. Steinbüchel. 2001. Characterization of the eugenol hydroxylase genes (ehyA/ehyB) from the new eugenol degrading isolate Pseudomonas sp. Strain OPS1. Applied Microbiology and Biotechnology. 56:724-730.

• Priefert H., J. Overhage and A. Steinbüchel. 1999. Identification and molecular characterization of the eugenol hydroxylase genes (ehyA/ehyB) of Pseudomonas sp. Strain HR199. Archives of Microbiology. 172:364-376.

• Overhage J., H. Priefert and A. Steinbüchel. 1999. Biochemical and genetic analyses of the ferulic acid catabolism in Pseudomonas sp. Strain HR199. Applied and Environmental Microbiology. 65:4837-4847.

• Overhage J., H. Priefert, J. Rabenhorst and A. Steinbüchel. 1999. Biotransformation of eugenol to vanillin by a mutant of Pseudomonas sp. Strain HR199 constructed by disruption of the vanillin dehydrogenase gene. Applied Microbiology and Biotechnology. 52:820-828.

• Overhage J., A. U. Kresse, H. Priefert, H. Sommer, G. Krammer, J. Rabenhorst and A. Steinbüchel. 1999. Molecular characterization of the genes pcaG and pcaH, encoding protocatechuate 3,4-dioxygenase, which are essential for vanillin catabolism in Pseudomonas sp. strain HR199. Applied and Environmental Microbiology. 65:951-96.

 

 

Anke Neidig, Nikola Strempel, Dr. Jörg Overhage, Beatrix Bugert, Janine Strehmel

Student research assistant

 

We are looking for a highly motivated, biology, biochemistry or bioengineering student with interest in practical laboratory work in the molecular microbiology or biotechnology field. The student research assistant will work independently on one of our current research projects within our working group. Laboratory work experience is an advantage.

 

Working hours (minimum 40 hours per month) and length of contract are negotiable. For more information, please contact Dr. Jörg Overhage.