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EPS II-Dependent Autoaggregation of Sinorhizobium meliloti Planktonic Cells

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Abstract

Planktonic cells of Sinorhizobium meliloti, a Gram-negative symbiotic bacterium, display autoaggregation under static conditions. ExpR is a LuxR-type regulator that controls many functions in S. meliloti, including synthesis of two exopolysaccharides, EPS I (succinoglycan) and EPS II (galactoglucan). Since exopolysaccharides are important for bacterial attachment, we studied the involvement of EPS I and II in autoaggregation of S. meliloti. Presence of an intact copy of the expR locus was shown to be necessary for autoaggregation. A mutant incapable of producing EPS I displayed autoaggregation percentage similar to that of parental strain, whereas autoaggregation was significantly lower for a mutant defective in biosynthesis of EPS II. Our findings clearly indicate that EPS II is the essential component involved in autoaggregation of planktonic S. meliloti cells, and that EPS I plays no role in such aggregation.

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Acknowledgments

This study was supported by grants from the Secretaría de Ciencia y Técnica de la UNRC, Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) and Consejo Nacional de Investigaciones Científicas y Técnicas of the República Argentina (CONICET). FS and LVR were supported by a fellowship from the CONICET. WG and AZ are Career Members of CONICET. We are grateful to Dr. Graham Walker for strains, and Dr. S. Anderson for editing the manuscript.

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Authors and Affiliations

  1. Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Ruta 36 km 601, X5804BYA-Río Cuarto, Córdoba, Argentina

    Fernando G. Sorroche, Luciana V. Rinaudi & Walter Giordano

  2. Fundación Instituto Leloir, IIBBA, CONICET and FCEyN, Universidad de Buenos Aires, Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina

    Ángeles Zorreguieta

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  1. Fernando G. Sorroche
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  2. Luciana V. Rinaudi
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  3. Ángeles Zorreguieta
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  4. Walter Giordano
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Correspondence to Walter Giordano.

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Sorroche, F.G., Rinaudi, L.V., Zorreguieta, Á. et al. EPS II-Dependent Autoaggregation of Sinorhizobium meliloti Planktonic Cells. Curr Microbiol 61, 465–470 (2010). https://doi.org/10.1007/s00284-010-9639-9

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  • DOI: https://doi.org/10.1007/s00284-010-9639-9

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