Bradyrhizobium canariense sp. nov., an acidtolerant endosymbiont that nodulates endemic genistoid legumes (Papilionoideae: Genisteae) from the Canary Islands, along with Bradyrhizobium japonicum bv. genistearum, Bradyrhizobium genospecies alpha and Bradyrhizobium genospecies beta

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The effect of the cationic dye Alcian Blue on the silver staining of bacterial lipopolysaccharide and its polysaccharide and lipid A portions in polyacrylamide gels was investigated. The polysaccharide was only stained when the gel was previously treated with the dye. The polysaccharide moiety was found to be responsible for the lipopolysaccharide staining with silver, whereas the lipid A seemed unimportant. Treatment with Alcian Blue may prove useful to detect hydrophilic components of lipopolysaccharide samples that could not be stained by the usual silver staining procedures.

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Rhizobacteria with properties related to plant growth-promotion were isolated from the rhizosphere of the perennial legume Chamaecytisus proliferus ssp. proliferus var. palmensis (tagasaste) growing in field conditions. Samples were collected in two localities of the Tenerife Island: La Laguna and El Tanque, NE and NW at 600 and 1000 meters above sea level, respectively, and in two seasons, winter and summer. The strains were isolated by using culture dependent procedures, and identified by phenotypic (culturable and biochemical) and genotypic (ERIC-PCR fingerprinting) features. The rhizosphere isolates formed a diverse community of mainly Gram-negative bacteria, with members of genera Pseudomonas, Burkholderia and Sphingomonas being predominant. A high level of selectivity was found in the rhizosphere environment as compared to the non-rhizosphere soil where Gram-positives were more abundant. Species richness (number of species) and species abundance were related to the sampling season and the locality, thus, samples obtained in winter at both sites had larger counts than samples obtained in summer, and the higher species richness was found in La Laguna. The species Pseudomonas fluorescens showed the highest number of properties related to plant growth promotion (PGP): 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, phytohormone production, nitrogen fixation, fungal growth inhibition and cyanogenesis, thus it seems to be the most suitable microorganism to be tested in PGP-field experiments.