Ribosomal Ribonucleic Acid Cistron Similarities and Taxonomic Neighborhood of Brucella and CDC Group Vd

Abstract

Hybridizations were performed between labeled ribosomal ribonucleic acids from Brucella abortus ATCC 2344sT (T = type strain) and from several other organisms on the one hand and deoxyribonucleic acids from type and representative Brucella strains and from many other gram-negative organisms on the other hand. Brucella forms a tight cluster, with deoxyribonucleic acid homologies close to 100% ; its closest neighbors are CDC group Vd, followed by Phyllobacterium. This Brucella ribosomal ribonucleic acid branch links most closely at about 73.1"C Tmce, with the Agrobacten'um-Rhizobium cluster, which is itself a member of ribosomal ribonucleic acid superfamily IV. The deoxyribonucleic acid base compositions of BrucelEa strains range from 57.9 to 59.2 mol% guanine plus cytosine; the average genome molecular weights of the six species range from 2.37 x 109 to 2.82 x 109.Nearly a century ago Bruce (4) isolated an organism from the spleens of undulant (Malta) fever patients. This was the first representative of the present genus Brucella, a group of organisms that cause brucellosis, a very widespread and economically important zoonosis which mainly infects cattle, sheep, goats and swine and produces an incapacitating disease in humans. For some time only three Brucella species were recognized (1, 2), Brucella melitensis, Brucella abortus, and Brucella suis, with the chief hosts being goats, cattle, and swine, respectively. Three more species, Brucella neotomae (desert wood rats), Brucella ovis ( (20,30). "Achromobacter" CDC group Vd contains organisms which were isolated mostly from clinical material; these organisms seem to be separated from all other known gram-negative, glucose-nonfermenting bacteria by a typical set of phenotypic features (7,21,32,33,41). The exact taxonomic affiliation of CDC group Vd has not been established yet. It was the purpose of the present study to substantiate the exact suprageneric position of Brucella and CDC group Vd in rRNA superfamily IV and the relationship of these organisms with the Rhizobiaceae. MATERIALS AND METHODSBacterial strains and growth media. All of the strains used are listed in Table 1. After we verified bacteriological purity by plating, microscopic observation, and Gram staining, the organisms were grown in mass cultures on media as described previously (20). The Brucella strains (except Brucella ovis) were grown in tryptic soy broth (Difco Laboratories, Detroit, Mich.); 500-ml batch cultures were shaken moderately in 2-liter Fernbach flasks at 35°C and harvested in the late exponential phase of growth. Brucella ovis NCTC 10512T was propagated in surface cultures on tryptic soy chocolate agar (5% [volhol] defibrinated sheep blood heated in molten agar base to 80°C for 15 min before pouring) at 35°C in an atmosphere containing about 5% oxygen and 5% C02. Francisella was grown aerobically at 35°C in surface cultures on cysteine heart agar (Difco) supplemented with 5% (volhol) sterile defibrinated sheep blood (Oxoid Ltd., London, England).Extraction of high-molecular-wei...

Evaluation of the relatedness of Brucella spp. and Ochrobactrum anthropi and description of Ochrobactrum intermedium sp. nov., a new species with a closer relationship to Brucella spp.

“…Moreover, coincidence between the analyses of the Western blots of whole-cell extracts and the 16s rRNA sequences was observed. Those results strengthen the position of the brucellae in a close relationship with soil bacteria and plant symbionts which had been shown by rRNA and lipid A analyses (De Ley et al, 1987;Moreno et al, 1990;Yanagi & Yamasoto 1993), further support the definition of a new Ochrobactrum species [which was implicit in previous DNA hybridization studies (Holmes et al, 1988)], and show that the proposed new species is closer to the brucellae than to the 0. anthropi type strain cluster. Computer-assisted protein profiling has often been used as a complementary method for DNA and RNA taxonomic analysis (Vandamme et al, 1996).…”

“…Finally, the results of this and previous works (De Ley et al, 1987;Holmes et al, 1988;Romero et al, 1995) show that the taxonomic status of bacteria routinely classified as 0. anthropi on the basis of conventional tests (Bizet & Bizet, 1995;Brivet et al, 1993;Chang et al, 1996;Cieslak et al, 1992;Ezzedine et al, 1994;Grandsden & Eykyn, 1992;Haditsch et al, 1994) should be revised. According to currently accepted criteria (Stackebrandt & Goebel, 1994), the degree of internal DNA-DNA homology of hybridization group 2 (relative binding ratio from 73 to 96%) (Homes et al, 1988), the relatively low crosshybridization with group 1 (from 41 to 51 %), and the closer similarity (16s rRNA, and Western blot of whole-cell proteins) of hybridization group 2 to the Brucella spp.…”

“…Previous studies (Holmes et al, 1988) have shown that B. abortus and 0. anthropi hybridization groups 1 (strain LMG 3331T) and 2 (strain LMG 3301) show 20-30 YO and 14-28 YO DNA homology, respectively, a result that does not allow assessment of the relative distances. However, perusal of the literature reveals that some of the strains used to define 0. anthropi (Holmes et al, 1988) had also been used in rRNA-DNA hybridization studies (De Ley et al, 1987), and that these studies had already suggested a closer relationship of the strains included in hybridization group 2 and the brucellae. Obviously, these data are confirmed and extended by the results of the present study.…”

Ochrobactrum anthropi gen. nov., sp. nov. from Human Clinical Specimens and Previously Known as Group Vd

“…The distinction into two biotypes is no longer recognized, and the taxon is referred to as group Vd (4). As determined by deoxyribonucleic acid (DNA)-ribosomal ribonucleic acid (rRNA) hybridization (7,17), guanine-plus-cytosine (G+C) content, type of respiratory quinone, and major fatty acid types (N. Ohishi, K. Yamasato, T. Kaneko, and H. Kuraishi, Abstr. XIV Int.…”

Classification of Pseudomonas aminovorans and Some Related Methylated Amine Utilizing Bacteria

“…Various members of the ribosomal ribonucleic acid (rRNA) superfamily IV sensu De Ley (1978), reproduce by budding division (L. B. Perry, personal communication), and the reference strain of P . aminovorans has already been allocated to the Rhizobium-Agrobacterium complex of this rRNA superfamily (De Ley et al, 1987). It was therefore important to examine the facultative methylotrophs in light of the above findings.…”