Attachment structures contribute to biofilm formation and xylem colonization of Erwinia amylovora
Biofilm formation, or the aggregation of bacteria in a matrix composed of exopolysaccharides and other macromolecules, contributes to bacterial pathogenesis and has been implicated in pathogen virulence, enhanced survival in stressful environments, and increased gene exchange. It has been shown that...
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| Published in: | Acta horticulturae no. 896; pp. 149 - 153 |
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| Main Authors: | , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
International Society for Horticultural Science
01-01-2011
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Biofilm formation, or the aggregation of bacteria in a matrix composed of exopolysaccharides and other macromolecules, contributes to bacterial pathogenesis and has been implicated in pathogen virulence, enhanced survival in stressful environments, and increased gene exchange. It has been shown that attachment to surfaces is a critical first step in biofilm formation. Biofilm formation plays an important role in the pathogenicity of Erwinia amylovora, specifically involving the exopolysaccharide pathogenicity factor amylovoran and the virulence factor levan. Evaluation of this process was further examined through the use of deletion mutants identified for structures that may have roles in attachment to surfaces or to other E. amylovora cells by bioinformatics. These putative mutants, delta hofC, delta hof operon, delta fimD, delta fim operon, delta flg operon 3, delta flg operon 4, delta crl, and delta eae were selected based on bioinformatic analyses, with single gene and operon deletion mutants generated and evaluated for biofilm formation capabilities, as well as pathogenicity. In vitro biofilm formation of mutants was quantified, and reduced biofilm formation was observed in deficient mutants. Mutants were evaluated for pathogenesis in both immature pear fruits, and shoots with similar results. Scanning electron microscopy was performed examining in planta biofilm formation, with results indicating that bacteria deficient in biofilm formation were either unable to orient to the correct and preferable location, the xylem tissue, or unable to develop a fully matured biofilm within the vascular tissue. Confocal microscopy using fluorescently labeled cells was also used to visualize the colonization and movement of the cells within apple vascular tissue. Results presented here not only suggest roles for several putative bacterial attachment structures, but also implicate the importance of biofilm formation during the xylem colonization process of E. amylovora pathogenesis. |
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| Bibliography: | http://www.actahort.org/ |
| ISSN: | 0567-7572 2406-6168 |
| DOI: | 10.17660/actahortic.2011.896.19 |