A. F. Yassin

Comparative chemotaxonomic and phylogenetic studies on the genus Arcanobacterium Collins et al. 1982 emend. Lehnen et al. 2006: proposal for Trueperella gen. nov. and emended description of the genus Arcanobacterium

The results of a study comparing the chemotaxonomic characteristics and phylogenetic positions of members of the genus Arcanobacterium indicated that the genus was not monophyletic and, therefore, was in need of taxonomic revision. Phylogenetically, the genus Arcanobacterium consisted of two distinct lines; a group comprising the species Arcanobacterium haemolyticum (the type species of the genus), A. hippocoleae, A. phocae and A. pluranimalium and a robust group consisting of the species A. abortisuis, A. bernardiae, A. bialowiezense, A. bonasi and A. pyogenes. On the basis of 16S rRNA signature nucleotide comparisons and menaquinone and phospholipid compositions, it is proposed that of these nine species only four, A. haemolyticum, A. hippocoleae, A. phocae and A. pluranimalium, should be affiliated with the genus Arcanobacterium and the species A. abortisuis, A. bernardiae, A. bialowiezense, A. bonasi and A. pyogenes should be reclassified as members of a new genus, Trueperella, as Trueperella abortisuis comb. nov., Trueperella bernardiae comb. nov., Trueperella bialowiezensis comb. nov., Trueperella bonasi comb. nov. and Trueperella pyogenes comb. nov. Positive results in Christie-Atkins-Munch-Petersen (CAMP) tests on A. haemolyticum, A. hippocoleae, A. phocae and A. pluranimalium also supported the rearrangement of the nine species in to separate genera. As such, an emended description of the genus Arcanobacterium is provided.

The cell wall porin of Nocardia farcinica: biochemical identification of the channel-forming protein and biophysical characterization of the channel properties

A channel‐forming protein was identified in cell wall extracts of the Gram‐positive, strictly aerobic bacterium Nocardia farcinica. The cell wall porin was purified to homogeneity and had an apparent molecular mass of about 87 kDa on tricine‐containing SDS–PAGE. When the 87 kDa protein was boiled for a longer time in sodium dodecylsulphate (SDS) it dissociated into two subunits with molecular masses of about 19 and 23 kDa. The 87 kDa form of the protein was able to increase the specific conductance of artificial lipid bilayer membranes from phosphatidylcholine (PC) phosphatidylserine (PS) mixtures by the formation of ion‐permeable channels. The channels had on average a single‐channel conductance of 3.0 nS in 1 M KCl, 10 mM Tris‐HCl, pH 8, and were found to be cation selective. Asymmetric addition of the cell wall porin to lipid bilayer membranes resulted in an asymmetric voltage dependence. The single‐channel conductance was only moderately dependent on the bulk aqueous KCl concentration, which indicated point charge effects on the channel properties. The analysis of the single‐channel conductance data in different salt solutions using the Renkin correction factor, and the effect of negative charges on channel conductance suggested that the diameter of the cell wall porin is about 1.4–1.6 nm. Channel‐forming properties of the cell wall porin of N. farcinica were compared with those of mycobacteria and corynebacteria. The cell wall porins of these members of the order Actinomycetales share common features because they form large and water‐filled channels that contain negative point charges.

Azospirillum rugosum sp nov., isolated from oil-contaminated soil

The taxonomic status of a light-orange-coloured bacterial isolate from an oil-contaminated soil sample was characterized by using a polyphasic taxonomic approach. Comparative analysis of 16S rRNA gene sequences demonstrated that the isolate belonged phylogenetically to the genus Azospirillum, with Azospirillum canadense, Azospirillum brasilense and Azospirillum doebereinerae as its closest phylogenetic relatives (97.3, 97.0 and 97.0 % similarity, respectively). DNA-DNA pairing studies showed that the unidentified organism displayed 25.0, 17.0 and 19.0 % relatedness to the type strains of A. brasilense, A. canadense and A. doebereinerae, respectively. The generic assignment was confirmed by chemotaxonomic data, which revealed a fatty acid profile that was characteristic of the genus Azospirillum, consisting of straight-chain saturated and unsaturated fatty acids with C18 : 1 omega 7c as the major fatty acid, and ubiquinone with ten isoprene units (Q-10) as the predominant respiratory quinone. On the basis of both the phenotypic and molecular genetic evidence, it is proposed that the unknown isolate be classified as a representative of a novel species of the genus Azospirillum, for which the name Azospirillum rugosum sp. nov. is proposed. The type strain is IMMIB AFH-6T (=CCUG 53966T=DSM 19657T).

Azospirillum picis sp. nov., isolated from discarded tar

A polyphasic taxonomic study was performed on a pink-coloured unknown bacterium isolated from discarded road tar. Comparative analysis of the 16S rRNA gene sequence demonstrated that the isolate belongs phylogenetically to the genus Azospirillum with Azospirillum lipoferum, A. melinis and A. rugosum as its closest phylogenetic relatives (96.7, 96.6 and 96.6 % similarity to the respective type strains). The generic assignment was confirmed on the basis of chemotaxonomic data, which revealed a fatty acid profile characteristic for the genus Azospirillum, consisting of straight-chain saturated and unsaturated fatty acids, with C(18 : 1)omega7c as the major unsaturated non-hydroxylated fatty acid, and C(16 : 0) 3-OH as the major hydroxylated fatty acid, and a ubiquinone with ten isoprene units (Q-10) as the predominant respiratory quinone. On the basis of both the phenotypic and molecular genetic evidence, it is proposed that the unknown isolate should be classified within a novel species of the genus Azospirillum, for which the name Azospirillum picis sp. nov. is proposed. The type strain is IMMIB TAR-3(T) (=CCUG 55431(T) =DSM 19922(T)).

Desmospora activa gen. nov., sp. nov., a thermoactinomycete isolated from sputum of a patient with suspected pulmonary tuberculosis, and emended description of the family Thermoactinomycetaceae Matsuo et al. 2006.

A novel Gram-positive, aerobic, catalase-positive, filamentous micro-organism, designated strain IMMIB L-1269(T), originating from sputum was characterized using phenotypic and molecular taxonomic methods. It showed cell-wall chemotype III, phospholipid type PII (with phosphatidylethanolamine as the diagnostic phospholipid) and contained an unsaturated menaquinone with seven isoprene units (MK-7) as the predominant isoprenoid quinone. It synthesized long-chain cellular fatty acids of the straight-chain saturated, monounsaturated and iso- and anteiso-branched types (with iso-C(15 : 0), C(16 : 0) and iso-C(17 : 0) predominating) and possessed a DNA G+C content of 49.3 mol%. On the basis of its morphological, biochemical and chemical characteristics, strain IMMIB L-1269(T) did not conform to any presently recognized taxon. Comparative analyses based on 16S rRNA gene sequences confirmed the distinctiveness of the isolate, as it displayed sequence-divergence values greater than 7.7 % with respect to recognized Gram-positive taxa. Phylogenetic treeing analysis served to reinforce the view that strain IMMIB L-1269(T) was distinct from recognized taxa, as it formed a relatively long subline branching within a 16S rRNA gene sequence cluster that encompassed the genera Thermoactinomyces, Laceyella, Mechercharimyces, Thermoflavimicrobium, Planifilum, Seinonella and Shimazuella of the family Thermoactinomycetaceae. On the basis of phenotypic and molecular phylogenetic evidence, strain IMMIB L-1269(T) represents a novel genus and species, for which the name Desmospora activa gen. nov., sp. nov. is proposed. The type strain of Desmospora activa is strain IMMIB L-1269(T) (=DSM 45169(T) =CCUG 55916(T)). An emended description of the family Thermoactinomycetaceae is also given.

The cell wall porin of the gram-positive bacterium Nocardia asteroides forms cation-selective channels that exhibit asymmetric voltage dependence.

Abstract Detergent-solubilized cell wall extracts of the gram-positive, strictly aerobic bacterium Nocardia asteroides contain channel-forming activity as judged from reconstitution experiments using lipid bilayer membranes. The cell wall porin was identified as a protein with an apparent molecular mass of about 84 kDa based on SDS-PAGE. The porin was purified to homogeneity using preparative SDS-PAGE. The 84-kDa protein was no longer observed after heating in SDS buffer. The presumed dissociation products were not observed on SDS-polyacrylamide gels. The cell wall porin increased the specific conductance of artificial lipid bilayer membranes from phosphatidylcholine/phosphatidylserine mixtures by the formation of cation-selective channels, which had an average single-channel conductance of 3.0 nS in 1 M KCl. The single-channel conductance was only moderately dependent on the bulk aqueous KCl concentration, which indicated negative point charge effects on the channel properties. The analysis of the concentration dependence of the single-channel conductance using the effect of negative charges on channel conductance suggested that the diameter of the cell wall channel is about 1.4 nm. Asymmetric addition of the cell wall porin to lipid bilayer membranes resulted in an asymmetric voltage dependence. The cell wall channel switched into substates, when the cis side of the membrane, the side of the addition of the protein, had negative polarity. Positive potentials at the cis side had no influence on the conductance of the cell wall channel.

Genotypic and phenotypic variation among Lysobacter capsici strains isolated from Rhizoctonia suppressive soils

Four Gram-negative bacterial strains, recovered from clay soils cultivated with different crops in the Netherland, were subjected to a polyphasic taxonomic study in order to clarify their taxonomic status. Comparative analysis of the 16S rRNA gene sequences revealed that they belong to the genus Lysobacter and to be highly related to the type strains of L. antibioticus DSM 2044(T), L. gummosus DSM 6980(T), and L. capsici DSM 19286(T), displaying 99.1-99.3%, 99.2-99.6% and 99.4-100% sequence similarities, respectively, to these species. The results of DNA-DNA hybridization studies unambigiously indicated that the four strains belonged to the species L. capsici. Nevertheless, DNA fingerprinting and phenotypic characterization indicated that there was a considerable diversification and niche differentiation among the strains belonging to L. capsici. The newly identified L. capsici strains strongly inhibit Rhizoctonia solani AG2 and originate from Rhizoctonia-suppressive soils where also populations of L. antibioticus and L. gummosus were present. This is the first report of the presence of combined populations of closely related Lysobacter spp. within agricultural soils.

Actinomadura sputi sp. nov., isolated from the sputum of a patient with pulmonary infection.

The taxonomic position of an actinomycete, strain IMMIB L-889(T), isolated from the sputum of a 64-year-old man, was determined using a polyphasic taxonomic approach. The strain had chemical and morphological properties that were consistent with its classification in the genus Actinomadura. It formed a distinct phyletic line in the 16S rRNA gene tree of Actinomadura and was most closely related to the type strain of Actinomadura hallensis (98.4 % sequence similarity), but could be readily distinguished from the latter species using DNA-DNA relatedness and phenotypic data. The combined genotypic and phenotypic data indicate that strain IMMIB L-889(T) represents a novel species of the genus Actinomadura, for which the name Actinomadura sputi sp. nov. is proposed. The type strain is IMMIB L-889(T) =DSM 45233(T)=CCUG 56589(T). [corrected]

Chryseobacterium treverense sp. nov., isolated from a human clinical source.

A yellow-pigmented, Gram-reaction-negative bacterium isolated from a human clinical source was investigated using a polyphasic approach in order to clarify its taxonomic status. Comparative 16S rRNA gene sequence analysis showed that the new isolate constituted a distinct phyletic line within the genus Chryseobacterium, displaying >2.8 % sequence divergence with recognized species of this genus. The generic assignment was confirmed by chemotaxonomic data which revealed a fatty acid profile consisting of straight-chain saturated, monounsaturated and branched-chain fatty acids of iso-/anteiso-types as well as 3-hydroxylated fatty acids; a menaquinone with six isoprene units (MK-6) as the predominant respiratory quinone and sym-homospermidine as the predominant polyamine. The novel isolate could be distinguished from other members of the genus Chryseobacterium by a set of distinct biochemical properties. On the basis of phenotypic and phylogenetic evidence, it is proposed that the new isolate represents a novel species of the genus Chryseobacterium for which the name Chryseobacterium treverense sp. nov. is proposed. The type strain is IMMIB L-1519(T) (=DSM 22251(T)=CCUG 57657(T)).

Bacteremia Caused by a Novel Helicobacter Species in a 28-Year-Old Man with X-Linked Agammaglobulinemia

ABSTRACT We report on a case of bacteremia caused by a previously unknown urease-negative Helicobacter strain, IMMIB HP-28/08, isolated from blood cultures of a 28-year-old man with X-linked agammaglobulinemia. The identification of the isolate was based on 16S rRNA gene sequencing. In the phylogenetic tree, the isolate fell into a cluster which included Helicobacter canadensis, Helicobacter equorum, and Helicobacter pullorum. This is the first report of bacteremia caused by this fastidious organism. Further investigations are necessary to determine the potential role of this species as a pathogen of bloodstream infections.