A potentially critical mutation was found in the csuB open reading

frame of strain ATCC 17978, a strain displaying lower levels of binding to abiotic surfaces MI-503 ic50 compared to the other fully sequenced strains. No direct correlation could be established between the presence or absence of other type I pili clusters and adherence. Overall, these studies demonstrate the significant diversity in phenotypic characteristics of clinical Acinetobacter isolates. Comparative analyses of the type IV pili genes between the sequenced strains examined revealed a potential role in motility. However, further investigation is required to fully delineate the mechanisms of motility and adherence in A. baumannii and the role of these phenotypes in promoting virulence of this important pathogen. This work was supported by Project Grant 535053 from the National Health and Medical Research Council Australia. B.E. is the recipient of a School of Biological Sciences Endeavour International Postgraduate Research Scholarship and

I.T.P. is the recipient of a Life Science Research Award from the NSW Office of Science and Medical Research. We would like to thank the various medical institutions and individuals (listed in Materials and methods) for their kind gifts of the clinical Acinetobacter isolates. Cell line A549 and Detroit 562 were kindly Pifithrin�� provided by Prof. J. Paton (University of Adelaide). “
“To compete in complex microbial communities, bacteria must sense environmental changes and adjust cellular functions for optimal growth. Chemotaxis-like signal transduction pathways are implicated in the regulation of multiple Dimethyl sulfoxide behaviors in response to changes in the environment, including motility patterns, exopolysaccharide production, and cell-to-cell interactions. In Azospirillum brasilense, cell surface properties, including exopolysaccharide

production, are thought to play a direct role in promoting flocculation. Recently, the Che1 chemotaxis-like pathway from A. brasilense was shown to modulate flocculation, suggesting an associated modulation of cell surface properties. Using atomic force microscopy, distinct changes in the surface morphology of flocculating A. brasilense Che1 mutant strains were detected. Whereas the wild-type strain produces a smooth mucosal extracellular matrix after 24 h, the flocculating Che1 mutant strains produce distinctive extracellular fibril structures. Further analyses using flocculation inhibition, lectin-binding assays, and comparison of lipopolysaccharides profiles suggest that the extracellular matrix differs between the cheA1 and the cheY1 mutants, despite an apparent similarity in the macroscopic floc structures. Collectively, these data indicate that disruption of the Che1 pathway is correlated with distinctive changes in the extracellular matrix, which likely result from changes in surface polysaccharides structure and/or composition.