HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Burdman, S. Articles by Okon, Y. Search for Related Content PubMed PubMed Citation Articles by Burdman, S. Articles by Okon, Y. Agricola Articles by Burdman, S. Articles by Okon, Y.

Involvement of outer-membrane proteins in the aggregation of Azospirillum brasilense

¹Department of Plant Pathology and Microbiology, and The Otto Warburg Center for Agricultural Biotechnology, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel
²Department of Animal Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel

ABSTRACT

A bioassay was developed to investigate biological factors involved in the aggregation of Azospirillum brasilense strain Cd. Cells were grown for 24 h under aggregation-inducing and non-aggregation-inducing conditions (high and low C:N, respectively) and sonicated for 20 s. The cells were washed by centrifugation and resuspended in potassium phosphate buffer containing the two types of sonication extract. A greater extent of aggregation and higher flocculation were observed after 2–3 h incubation in the presence of sonicates from cells grown at high C:N (H-cells) compared to cells grown at low C:N. Flocculation did not occur after incubation of these cells in phosphate buffer. Boiled or proteinase K-treated sonicates originating from H-cells had lower aggregation-inducing capacity. After fractionation of the crude sonicate, both the outer-membrane protein (OMP) and the total membrane (mostly OMP) fractions possessed relatively high aggregation specific activities. The aggregation-inducing capacity of the OMP fraction strongly correlated with its protein concentration in the bioassay. Treatment of this fraction with proteinase K also decreased its aggregation-inducing activity. These findings suggest that OMPs are involved in the aggregation process of cells of A. brasilense.

Author for correspondence: Yaacov Okon. Tel: +972 8 9481216. Fax: +972 8 9466794. e-mail: okon@agri.huji.ac.il

This article has been cited by other articles:

				A. Lerner, Y. Okon, and S. Burdman The wzm gene located on the pRhico plasmid of Azospirillum brasilense Sp7 is involved in lipopolysaccharide synthesis Microbiology, March 1, 2009; 155(3): 791 - 804. [Abstract] [Full Text] [PDF]

				S. Uzureau, M. Godefroid, C. Deschamps, J. Lemaire, X. De Bolle, and J.-J. Letesson Mutations of the Quorum Sensing-Dependent Regulator VjbR Lead to Drastic Surface Modifications in Brucella melitensis J. Bacteriol., August 15, 2007; 189(16): 6035 - 6047. [Abstract] [Full Text] [PDF]

				D. Kadouri, E. Jurkevitch, and Y. Okon Involvement of the Reserve Material Poly-{beta}-Hydroxybutyrate in Azospirillum brasilense Stress Endurance and Root Colonization Appl. Envir. Microbiol., June 1, 2003; 69(6): 3244 - 3250. [Abstract] [Full Text] [PDF]

				D. Kadouri, S. Burdman, E. Jurkevitch, and Y. Okon Identification and Isolation of Genes Involved in Poly({beta}-Hydroxybutyrate) Biosynthesis in Azospirillum brasilense and Characterization of a phbC Mutant Appl. Envir. Microbiol., June 1, 2002; 68(6): 2943 - 2949. [Abstract] [Full Text] [PDF]