Nodulation ofLupinus albusby Strains ofOchrobactrum lupinisp. nov

Abstract

The nodulation of legumes has for more than a century been considered an exclusive capacity of a group of microorganisms commonly known as rhizobia and belonging to the ␣-Proteobacteria. However, in the last 3 years four nonrhizobial species, belonging to ␣ and ␤ subclasses of the Proteobacteria, have been described as legume-nodulating bacteria. In the present study, two fast-growing strains, LUP21 and LUP23, were isolated from nodules of Lupinus honoratus. The phylogenetic analysis based on the 16S and 23S rRNA gene sequences showed that the isolates belong to the genus Ochrobactrum. The strains were able to reinfect Lupinus plants. A plasmid profile analysis showed the presence of three plasmids. The nodD and nifH genes were located on these plasmids, and their sequences were obtained. These sequences showed a close resemblance to the nodD and nifH genes of rhizobial species, suggesting that the nodD and nifH genes carried by strain LUP21 T were acquired by horizontal gene transfer. A polyphasic study including phenotypic, chemotaxonomic, and molecular features of the strains isolated in this study showed that they belong to a new species of the genus Ochrobactrum for which we propose the name Ochrobactrum lupini sp. nov. Strain LUP21 T (LMG 20667 T ) is the type strain.Plants from the family Leguminosae are usually capable of dinitrogen fixation because of their symbiotic interaction with nodulating bacteria belonging to the order Rhizobiales. Most bacteria that establish a symbiosis with legume plants, including some nonrhizobial species of Methylobacterium (16, 45) and Devosia (40, 41), belong to the ␣ subclass of Proteobacteria, although some species from genera of the ␤ subclass, such as Ralstonia and Burkholderia, can also nodulate legumes (6,32,53). In the last few years there has been an increasing amount of research focused on bacteria that nodulate stems or roots of tropical legume species. However, the identity of many of the endosymbionts of temperate legumes still remains unknown. The genus Lupinus groups up to 200 species of herbs and small shrubs, broadly distributed in the Mediterranean area and in the American continent, where they colonize very different environments. Despite the agronomic and ecological interest of Lupinus, this plant has been poorly studied with respect to its symbionts. Plants from the genus Lupinus are nodulated by fast-and slow-growing rhizobia; however, slow-growing rhizobia are more frequently isolated from this legume (3,5,21,30). The data obtained from the small-subunit (SSU) rRNA gene indicate a very close relationship between some bradyrhizobia isolated from Lupinus and Bradyrhizobium japonicum (3,12,30). However, bacterial strains nodulating Lupinus plants have been poorly characterized thus far, and fast-growing species nodulating this legume have not been not officially described; nevertheless, in the past the species Rhizobium lupini was proposed (15) and was later abandoned (14).During a study of rhizobia nodulating Lupinus plants in several geographical regi...

Zhangella mobilis gen. nov., sp. nov., a new member of the family Hyphomicrobiaceae isolated from coastal seawater

“…nov. E6 T ; 2, Cucumibacter; 3, Devosia; 4, Ahrensia; 5, Ochrobactrum. Data were taken from this study, Hwang & Cho (2008), Ryu et al (2008), Vanparys et al (2005), Rivas et al (2003), Nakagawa et al (1996), Rüger & Höfle (1992), Teyssier et al (2007), Uchino et al (1998), Tripathi et al (2006), Zurdo-Piñeiro et al (2007) and Trujillo et al (2005). All taxa were positive for catalase and oxidase activity.…”

A large diversity of non-rhizobial endophytes found in legume root nodules in Flanders (Belgium)

“…While traditionally, rhizobia belonged to the genera, Azorhizobium, Bradyrhizobium, Ensifer, Mesorhizobium and Rhizobium (Sawada et al, 2003), in recent years nitrogen fixing root nodule bacteria have also been described in other Alphaproteobacterial genera, including Ochrobactrum (Trujillo et al, 2005), Methylobacterium (Sy et al, 2001), Microvirga (Ardley et al, 2012;Radl et al, 2014), Devosia (Rivas et al, 2003) and Phyllobacterium . Furthermore, so-called Betarhizobia have in the last ten years been described in the Betaproteobacterial genera Burkholderia and Cupriavidus (Chen et al, 2001;Moulin et al, 2001;De Meyer et al, 2013a;De Meyer et al, 2013b;De Meyer et al, 2014).…”

Shinella kummerowiae sp. nov., a symbiotic bacterium isolated from root nodules of the herbal legume Kummerowia stipulacea

“…In addition to species in the genera Allorhizobium, Azorhizobium, Bradyrhizobium, Mesorhizobium, Rhizobium and Ensifer (former Sinorhizobium species), symbiotic strains belonging to a wide range of bacterial genera have been reported recently from root nodules of several legume species, including Devosia neptuniae (Rivas et al, 2002), Methylobacterium nodulans (Sy et al, 2001), Ochrobactrum lupini (Trujillo et al, 2005) and Ochrobactrum cytisi (ZurdoPiñeiro et al, 2007) in the Alphaproteobacteria, plus several species of Ralstonia (Chen et al, 2001) and Burkholderia (Moulin et al, 2000;Vandamme et al, 2002) in the Betaproteobacteria. Meanwhile, some non-symbiotic bacteria related to symbiotic species have also been isolated from root nodules (Chou et al, 2007;Trujillo et al, 2006).…”

“…In the present study, strain CCBAU 25048 T , S. granuli JCM 13254 T , S. zoogloeoides JCM 20728 T , Rhizobium etli CFN 42 T , Rhizobium leguminosarum USDA 2370 T , Ensifer meliloti USDA 1002 T and Mesorhizobium loti NZP 2213 T were incubated in YMA medium (Vincent, 1970) at 28 u C. DNA extracted from these strains with the method of Terefework et al (2001) was used in TP-RAPD analysis as described previously (Trujillo et al, 2005). The patterns acquired (Fig.…”