Polar lipid composition in the classification ofArthrobacterandMicrobacterium

Arthrobacter sunyaminii sp. nov. and Arthrobacter jiangjiafuii sp. nov., new members in the genus Arthrobacter

Four novel bacterial strains (zg-ZUI122T/zg-ZUI10 and zg-ZUI227T/zg-ZUI100) were isolated from the intestinal contents of Marmota himalayana and characterized using a polyphasic approach. Cells were Gram-stain- and catalase-positive, urease- and oxidase-negative. Strains grew optimally at 28–30 °C, pH 7.0, with 0.5 % NaCl (w/v). A comparative analysis of 16S rRNA gene sequences revealed that strain pairs zg-ZUI122T/zg-ZUI10 and zg-ZUI227T/zg-ZUI100 belonged to the genus Arthrobacter and were most closely related to Arthrobacter citreus DSM 20133T, with similarities of 99.6 and 99.5 %, respectively. This was further confirmed by phylogenetic analyses based on the 16S rRNA gene and genome sequences. The digital DNA–DNA hybridization and average nucleotide identity values between the two new type strains (zg-ZUI122T and zg-ZUI227T) and other species in the genus Arthrobacter were 20.0–24.4/77.2–83.4% and 19.9–25.1/77.1–83.4%, all below the thresholds. The major cellular fatty acids detected in the two novel species included iso-C15 : 0 and anteiso-C15 : 0; the predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. MK-8(H2) (77.3%) was the predominant respiratory quinone detected in strain zg-ZUI122T, while MK-8(H2) (53.7%) and MK-9(H2) (46.3%) were detected in strain zg-ZUI227T. The shared cell-wall amino acids detected in the two novel species were alanine, glutamic acid and lysine; the shared whole cell wall sugars consisted of galactose, mannose and ribose. All these analyses concluded that these four strains represent two different novel species in the genus Arthrobacter , for which the names Arthrobacter sunyaminii sp. nov. (zg-ZUI122T = GDMCC 1.2502T = KCTC 49677T) and Arthrobacter jiangjiafuii sp. nov. (zg-ZUI227T = GDMCC 1.2500T = KCTC 49676T) are proposed.

Kibdelosporangium persicum sp. nov., a new member of the Actinomycetes from a hot desert in Iran

Isolate 4NS15^T was isolated from a neglected arid habitat in Kerman, Iran. The strain showed 16S rRNA gene sequence similarity values of 98.9 % to the type strains of Kibdelosporangium aridum subsp. aridum, Kibdelosporangium phytohabitans and Kibdelosporangium philippinense and 98.6 % to the type strain K. aridum subsp. largum, respectively. Genome-based phylogenetic analysis revealed that isolate 4NS15^T is closely related to Kibdelosporangium aridum subsp. aridum DSM 43828^T. The digital DNA-DNA hybridization value between the genome sequences of 4NS15^T and strain DSM 43828^T is 29.8 %. Strain 4NS15^T produces long chains of spores without a sporangium-like structure which can be distinguished from other Kibdelosporangium species. Isolate 4NS15^T has a genome size of 10.35 Mbp with a G+C content of 68.1 mol%. Whole-cell hydrolysates of isolate 4NS15^T are rich in meso-diaminopimelic acid and cell-wall sugars such as arabinose, galactose, glucose and ribose. Major fatty acids (>10 %) are C_16 : 0, iso-C_16 : 0 and iso-C_15 : 0. The phospholipid profile contains diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylhydroxyethanolamine, aminolipid and glycoaminolipid. The predominant menaquinone is MK-9(H₄). Based on its phenotypic and genotypic characteristics, isolate 4NS15^T (NCCB 100701=CIP 111705=DSM 110728) merits recognition as representing a novel species of the genus Kibdelosporangium, for which the name Kibdelosporangium persicum sp. nov. is proposed.

Pseudarthrobacter psychrotolerans sp. nov., a cold-adapted bacterium isolated from Antarctic soil

A novel cold-tolerant bacterium, designated strain YJ56T, was isolated from Antarctic soil collected from the Cape Burk area. Phylogenetic analysis through 16S rRNA gene sequence similarity revealed that strain YJ56T was most closely related to the genus Pseudarthrobacter , including Pseudarthrobacter oxydans DSM 20119T (99.06 % similarity), Pseudarthrobacter polychromogenes DSM 20136T (98.98 %) and Pseudarthrobacter sulfonivorans ALLT (98.76 %). The genome size (5.2 Mbp) of strain YJ56T was the largest among all the published genomes of Pseudarthrobacter type strains (4.2–5.0 Mbp). The genomic G+C content of strain YJ56T (64.7 mol%) was found to be consistent with those of other Pseudarthrobacter strains (62.0–71.0 mol%). The average nucleotide identity and average amino acid identity values between strain YJ56T and P. sulfonivorans ALLT were estimated at 84.1 and 84.2 %, respectively. The digital DNA–DNA hybridization value between the two strains was calculated to be 28.0 %. This rod-shaped and obligate aerobic strain exhibited no swimming or swarming motility. It had catalase activity but no oxidase activity. Cells grew at 4–28 °C (optimum, 13 °C) and pH 5.0–11.0 (optimum, pH 7.0) and with 0–6.0 % (w/v) NaCl (optimum, 0%) in Reasoner's 2A medium. MK-9 (H2) was the sole menaquinone. Two-dimensional TLC results revealed that the primary polar lipids were diphosphatidylglycerol, phosphatidylglycerol, two glycolipids and phosphatidylinositol. Fatty acid methyl ester analysis showed that anteiso-C15 : 0, anteiso-C17 : 0, iso-C15 : 0, C16 : 0 and iso-C16 : 0 were the major cellular fatty acids in strain YJ56T. Based on phenotypic and genotypic characteristics, strain YJ56T represents a novel species of the genus Pseudarthrobacter , and thus the name Pseudarthrobacter psychrotolerans sp. nov is proposed. The type strain is YJ56T (=JCM 33881T=KACC 21510T).

Review of the taxonomy of the genus Arthrobacter, emendation of the genus Arthrobacter sensu lato, proposal to reclassify selected species of the genus Arthrobacter in the novel genera Glutamicibacter gen. nov., Paeniglutamicibacter gen. nov., Pseudoglutamicibacter gen. nov., Paenarthrobacter gen. nov. and Pseudarthrobacter gen. nov., and emended description of Arthrobacter roseus

In this paper, the taxonomy of the genus Arthrobacter is discussed, from its first description in 1947 to the present state. Emphasis is given to intrageneric phylogeny and chemotaxonomic characteristics, concentrating on quinone systems, peptidoglycan compositions and polar lipid profiles. Internal groups within the genus Arthrobacter indicated from homogeneous chemotaxonomic traits and corresponding to phylogenetic grouping and/or high 16S rRNA gene sequence similarities are highlighted. Furthermore, polar lipid profiles and quinone systems of selected species are shown, filling some gaps concerning these chemotaxonomic traits. Based on phylogenetic groupings, 16S rRNA gene sequence similarities and homogeneity in peptidoglycan types, quinone systems and polar lipid profiles, a description of the genus Arthrobacter sensu lato and an emended description of Arthrobacter roseus are provided. Furthermore, reclassifications of selected species of the genus Arthrobacter into novel genera are proposed, namely Glutamicibacter gen. nov. (nine species), Paeniglutamicibacter gen. nov. (six species), Pseudoglutamicibacter gen. nov. (two species), Paenarthrobacter gen. nov. (six species) and Pseudarthrobacter gen. nov. (ten species).

Description of Tersicoccus phoenicis gen. nov., sp. nov. isolated from spacecraft assembly clean room environments

Two strains of aerobic, non-motile, Gram-reaction-positive cocci were independently isolated from geographically distinct spacecraft assembly clean room facilities (Kennedy Space Center, Florida, USA and Centre Spatial Guyanais, Kourou, French Guiana). A polyphasic study was carried out to delineate the taxonomic identity of these two isolates (1P05MAT and KO_PS43). The 16S rRNA gene sequences exhibited a high similarity when compared to each other (100 %) and lower than 96.7 % relatedness with Arthrobacter crystallopoietes ATCC 15481T, Arthrobacter luteolus ATCC BAA-272T, Arthrobacter tumbae DSM 16406T and Arthrobacter subterraneus DSM 17585T. In contrast with previously described Arthrobacter species, the novel isolates maintained their coccidal morphology throughout their growth and did not exhibit the rod–coccus life cycle typically observed in nearly all Arthrobacter species, except A. agilis . The distinct taxonomic identity of the novel isolates was confirmed based on their unique cell-wall peptidoglycan type (A.11.20; Lys-Ser-Ala2) and polar lipid profile (presence of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, an unknown phospholipid and two unknown glycolipids). The G+C content of the genomic DNA was 70.6 mol%. The novel strains revealed MK-9(H2) and MK-8(H2) as dominant menaquinones and exhibited fatty acid profiles consisting of major amounts of anteiso-C15 : 0 and anteiso-C17 : 0 and moderate amounts of iso-C15 : 0 discriminating them again from closely related Arthrobacter species. Based on these observations, the authors propose that strains 1P05MAT and KO_PS43 be assigned into a separate genus Tersicoccus gen. nov. For this new taxon, comprising strains 1P05MAT and KO_PS43, we propose the name Tersicoccus phoenicis gen. nov., sp. nov. (the type species of Tersicoccus), represented by the type strain Tersicoccus phoenicis 1P05MAT ( = NRRL B-59547T = DSM 30849T).

Lipids in the classification of Nocardioides: reclassification of Arthrobacter simplex (Jensen) lochhead in the genus Nocardioides (Prauser) emend. O'Donnell et al. as Nocardioides simplex comb. nov

Representative strains of Nocardioides, Arthrobacter simplex and Arthrobacter tumescens were degraded by acid methanolysis and the fatty acid esters released examined by thin-layer and gas chromatography. Branched-chain 14-methylpentadecanoic acid (iso-16) was the predominant component in all but one of the Nocardioides strains. Arthrobacter simplex also contained major amounts of this acid whereas A. tumescens had only minor amounts. All of the test strains possessed 15 and 17 carbon straight chain acids, tuberculostearic acid (10-methyloctadecanoic acid) and its 17 and 18-carbon homologues. The fatty acid profiles of Nocardioides strains lacked 13-methyltetradecanoic and heptadecanoic acids which were both present in Arthrobacter simplex and Arthrobacter tumescens. The profiles of these latter organisms were quantitatively different from each other. The polar lipids of the test strains all contained diphosphatidylglycerol and phosphatidylglycerol but only Arthrobacter tumescens contained phosphatidylinositol and three unidentified polar lipids. Nocardioides and Arthrobacter simplex strains all contained two very characteristic closely related polar lipids. All of the test strains contained tetrahydrogenated menaquinones with eight isoprene units as the major isoprenologue. The results of the present study support the integrity of the genus Nocardioides and provide a reliable way of distinguishing it from other actinomycetes, such as Streptomyces, which also have LL-diaminopimelic acid and glycine in the peptidoglycan. The lipid data, together with results from chemical, genetic and phage host range studies, provide sufficient grounds for the transfer of Arthrobacter simplex to Nocardioides as Nocardioides simplex comb. nov. An emended description of the genus Nocarioides is given.