Ochrobactrum

Abstract: In this study we examined the taxonomic relationships of strains variously labeled Achromobacter species biotypes 1 and 2, Achromobacter group A, and Centers for Disease Control (CDC) groups Vd-1 and Vd-2. Previous studies of ribosomal ribonucleic acid cistron similarities placed these organisms on the Brucella ribosomal ribonucleic acid branch of ribosomal ribonucleic acid superfamily IV; their closest neighbors were Brucella, Phyllobacterium, and the Agrobacterium-Rhizobium complex. We performed a numerical taxonomic analysis of 284 phenotypic features (69 conventional tests, 147 API assimilation tests, 68 API ZYM tests) carried out on 95 strains. These organisms comprised 56 strains thought to correspond to CDC group Vd (including 3 strains originally labeled “Pseudomonas arsenoxydans”) and 39 strains (included for reference purposes) representing the genera Achromobacter, Agrobacterium, Alcaligenes, Brucella, Mycoplana, Phyllobacterium, and Rhizobium. A phenotypic analysis showed that group Vd bacteria are most similar to Phyllobacterium. However, strains of Group Vd were shown to be distinct by deoxyribonucleic acid (DNA)-DNA hybridization and by several phenotypic tests from Phyllobacterium and other related taxa. The CDC group Vd strains formed essentially a single taxon in the numerical taxonomic analysis of phenotypic characters and as determined by DNA-DNA hybridization. This taxon could be subdivided into three biotypes (biotypes A, C, and D), but none of these corresponded to the two biotypes originally described among the group Vd strains. For CDC group Vd we propose a new genus and new species, Ochrobactrum anthropi: The type strain is strain CIP 82.115 (= CIP 14970 = NCTC 12168 = LMG 3331). O. anthropi strains are rod shaped, aerobic, gram negative, nonpigmented, and motile by means of peritrichous flagella, produce acid from several carbohydrates, and reduce both nitrate and nitrite. The guanine-plus-cytosine contents of the DNAs of 29 strains ranged from 56 to 59 mol%. Almost all 56 group Vd strains were originally isolated from various human clinical specimens, commonly from blood cultures.

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 α-Proteobacteria. However, in the last 3 years four nonrhizobial species, belonging to α and β 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 LUP21T 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 LUP21T (LMG 20667T) is the type strain.

Abstract: The relatedness of Brucella spp and Ochrobactrum anthropi was studied by protein profiling, Western blot, immunoelectrophoresis and 16S rRNA analysis Whole-cell and soluble proteins of brucellae and O anthropi showed serological cross-reactivities quantitatively and qualitatively more intense than those existing with similar extracts of Agrobacterium spp Numerical analysis of Western blot profiles of whole-cell extracts showed that O anthropi LMG 3301 was closer to Brucella spp than to O anthropi LMG 3331Ta result not obtained by protein profiling These differences were not observed by Western blot with soluble fractions, and immunoelectrophoretic analyses suggested that this was due to destruction of conformational epitopes in Western blot procedures with the subsequent simplification of antigenic profile Analysis of the 16S rRNA sequences of strains previously used in the species definition confirmed that strain LMG 3301, and also LMG 3306, were closer to the brucellae, and that LMG 3331Twas in a separate cluster The LMG 3301 and the LMG 3331Tclusters could also be separated by their different colistin sensitivity and by PCR with 16S rRNA Brucella primers, and both methods showed strains of both clusters among clinical isolates classified as O anthropi by conventional tests These results and those of previous DNA-DNA hybridization studies [Holmes, B, Popoff, M, Kiredjian, M & Kersters, K (1988) Int J Syst Bacteriol 38, 406–416] show that the LMG 3301 cluster and related clinical isolates should be given a new species status for which the name Ochrobactrum intermedium sp nov is proposed (type strain is LMG 3301T= NCTC 12171T= CNS 2-75T)

Abstract: Two strains named ESC1(T) and ESC5 were isolated from nodules of Cytisus scoparius growing in a Spanish soil Phylogenetic analysis of the 16S rRNA gene showed that these strains belong to the genus Ochrobactrum, their closest relatives being Ochrobactrum anthropi and Ochrobactrum lupini, with 100 and 999 % similarity to the respective type strains Despite this high similarity, the results of DNA-DNA hybridization, phenotypic tests and fatty acid analyses showed that these strains represent a novel species of genus Ochrobactrum The DNA-DNA hybridization values were respectively 70, 66 and 55 % with respect to O lupini LUP21(T), O anthropi DSM 6882(T) and Ochrobactrum tritici DSM 13340(T) The predominant fatty acids were C(18 : 1)omega7c and C(18 : 1) 2-OH Strains ESC1(T) and ESC5 were strictly aerobic and were able to reduce nitrate and to hydrolyse aesculin They produced beta-galactosidase and beta-glucosidase and did not produce urease after 48 h incubation The G+C content of strain ESC1(T) was 564 mol% Both strains ESC1(T) and ESC5 contained nodD and nifH genes on megaplasmids that were related phylogenetically to those of rhizobial strains nodulating Phaseolus, Leucaena, Trifolium and Lupinus From the results of this work, we propose that the strains isolated in this study be included in a novel species named Ochrobactrum cytisi sp nov The type strain is ESC1(T) (=LMG 22713(T)=CECT 7172(T))