Microarrays Research Today is a free monthly online journal that collates and summarizes the latest research about Microarrays, including details on experiments, designs, statistics, analysis, software.

Metabolic capacity of Sinorhizobium (Ensifer) meliloti strains detected by phenotype microarray.

Biondi EG, Tatti E, Comparini D, Giuntini E, Mocali S, Giovannetti L, Bazzicalupo M, Mengoni A, Viti C

Department of Evolutionary Biology, University of Florence, via Romana, 17, Florence, Italy; Department of Agricultural Biotechnology, Section of Microbiology, University of Florence, Piazzale delle Cascine 24, I-50144, Florence, Italy; Department of Biology (Area 3), University of York, PO Box 373, York YO10 5YW, UK; C.R.A. - Centro di Ricerca per lo Studio delle Relazioni tra Pianta e Suolo, Via della Navicella, 2-4, 00184, Rome, Italy.

Sinorhizobium meliloti is a soil bacterium that fixes atmospheric nitrogen in plant roots. The high genetic diversity of its natural populations has been the subject of extensive analysis. Recent genomic studies on several isolates revealed a high content of variable genes suggesting a corresponding large phenotypic differentiation among strains of S. meliloti species. Here, using the Phenotype Microarray (PM) technique, hundreds of different growth conditions were tested in order to compare the metabolic capabilities of the laboratory reference strain Rm1021 with four natural S. meliloti isolates, previously analyzed by comparative genomic hybridization (CHG). Results of PM analysis showed that most phenotypic differences involved carbon source utilization and tolerance to osmolytes and pH, while fewer differences were scored for nitrogen, phosphorus and sulfur source utilization. Only the variability of the tested strain in tolerance to sodium nitrite and ammonium sulfate pH 8 was hypothesized to be associated with the genetic polymorphisms detected by CGH analysis. Also colony and cell morphology and ability to nodulate Medicago truncatula plants were compared revealing further phenotypic diversity. Overall, our results suggest that the study of functional (phenotypic) variability of S. meliloti populations is an important and complementary step in the investigation of genetic polymorphism of rhizobia, and may help to elucidate rhizobial evolutionary dynamics, including adaptation to diverse environments.

Published 29 June 2009 in Appl Environ Microbiol.
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