Micromonospora parastrephiae sp. nov. and Micromonospora tarensis sp. nov., isolated from the rhizosphere of a Parastrephia quadrangularis plant growing in the Salar de Tara region of the Central Andes in Chile.

Two novel Micromonospora strains, STR1-7T and STR1S-6T, were isolated from the rhizosphere of a Parastrephia quadrangularis plant growing in the Salar de Tara region of the Atacama Desert, Chile. Chemotaxonomic, cultural and phenotypic features confirmed that the isolates belonged to the genus Micromonospora. They grew from 20 to 37 °C, from pH7 to 8 and in the presence of up to 3 %, w/v NaCl. The isolates formed distinct branches in Micromonospora gene trees based on 16S rRNA gene sequences and on a multi-locus sequence analysis of conserved house-keeping genes. A phylogenomic tree generated from the draft genomes of the isolates and their closest phylogenetic neighbours showed that isolate STR1-7T is most closely related to Micromonospora orduensis S2509T, and isolate STR1S-6 T forms a distinct branch that is most closely related to 12 validly named Micromonospora species, including Micromonospora saelicesensis the earliest proposed member of the group. The isolates were separated from one another and from their closest phylogenomic neighbours using a combination of chemotaxonomic, genomic and phenotypic features, and by low average nucleotide index and digital DNA-DNA hybridization values. Consequently, it is proposed that isolates STR1-7T and STR1S-6T be recognized as representing new species in the genus Micromonospora, namely as Micromonospora parastrephiae sp. nov. and Micromonospora tarensis sp. nov.; the type strains are STR1-7T (=CECT 9665T=LMG 30768T) and STR1S-6T (=CECT 9666T=LMG 30770T), respectively. Genome mining showed that the isolates have the capacity to produce novel specialized metabolites, notably antibiotics and compounds that promote plant growth, as well as a broad-range of stress-related genes that provide an insight into how they cope with harsh abiotic conditions that prevail in high-altitude Atacama Desert soils.

Microbacterium plantarum sp. nov. and Microbacterium thalli sp. nov., two endophytic metal-resistant bacteria isolated from Sphaeralcea angustifolia (Cav.) G. Don and Prosopis laevigata (Humb. et Bonpl. ex Willd) M.C. Johnston.

Four Gram-positive, aerobic, catalase- and oxidase-negative, rod-shaped, motile endophytic bacterial strains, designated NM3R9T, NE1TT3, NE2TL11 and NE2HP2T, were isolated from the inner tissues (leaf and stem) of Sphaeralcea angustifolia and roots of Prosopis laevigata. They were characterized using a polyphasic approach, which revealed that they represent two novel Microbacterium species. Phylogenetic analysis based on 16S rRNA gene sequencing showed that the species closest to NE2HP2T was Microbacterium arborescens DSM 20754T (99.6 %) and that closest to NM3R9T, NE2TL11 and NE2TT3 was Microbacterium oleivorans NBRC 103075T (97.4 %). The whole-genome average nucleotide identity value between strain NM3R9T and Microbacterium imperiale DSM 20530T was 90.91 %, and that between strain NE2HP2T and M. arborecens DSM 20754T was 91.03 %. Digital DNA-DNA hybridization showed values of less than 70 % with the type strains of related species. The polar lipids present in both strains included diphosphatidylglycerol, phosphatidylglycerol, glycolipids and unidentified lipids, whereas the major fatty acids included anteiso-C15 : 0, anteiso-C17 : 0, iso-C16 : 0 and C16 : 0. Whole-cell sugars included mannose, rhamnose and galactose. Strains NM3R9T and NE2HP2T showed physiological characteristics different from those present in closely related Microbacterium species. According to the taxonomic analysis, both strains belong to two novel species. The name Microbacterium plantarum sp. nov. is proposed for strain NE2HP2T (=LMG 30875T=CCBAU 101117T) and Microbacterium thalli sp. nov. for strains NM3R9T (=LMG 30873T=CCBAU 101116T), NE1TT3 (=CCBAU 101114) and NE2TL11 (=CCBAU 101115).

Frankia alni Carbonic Anhydrase Regulates Cytoplasmic pH of Nitrogen-Fixing Vesicles.

A phyloprofile of Frankia genomes was carried out to identify those genes present in symbiotic strains of clusters 1, 1c, 2 and 3 and absent in non-infective strains of cluster 4. At a threshold of 50% AA identity, 108 genes were retrieved. Among these were known symbiosis-associated genes such as nif (nitrogenase), and genes which are not know as symbiosis-associated genes such as can (carbonic anhydrase, CAN). The role of CAN, which supplies carbonate ions necessary for carboxylases and acidifies the cytoplasm, was thus analyzed by staining cells with pH-responsive dyes; assaying for CO2 levels in N-fixing propionate-fed cells (that require a propionate-CoA carboxylase to yield succinate-CoA), fumarate-fed cells and N-replete propionate-fed cells; conducting proteomics on N-fixing fumarate and propionate-fed cells and direct measurement of organic acids in nodules and in roots. The interiors of both in vitro and nodular vesicles were found to be at a lower pH than that of hyphae. CO2 levels in N2-fixing propionate-fed cultures were lower than in N-replete ones. Proteomics of propionate-fed cells showed carbamoyl-phosphate synthase (CPS) as the most overabundant enzyme relative to fumarate-fed cells. CPS combines carbonate and ammonium in the first step of the citrulline pathway, something which would help manage acidity and NH4+. Nodules were found to have sizeable amounts of pyruvate and acetate in addition to TCA intermediates. This points to CAN reducing the vesicles' pH to prevent the escape of NH3 and to control ammonium assimilation by GS and GOGAT, two enzymes that work in different ways in vesicles and hyphae. Genes with related functions (carboxylases, biotin operon and citrulline-aspartate ligase) appear to have undergone decay in non-symbiotic lineages.

A Nonspecific Lipid Transfer Protein with Potential Functions in Infection and Nodulation.

The response of Alnus glutinosa to Frankia alni ACN14a is driven by several sequential physiological events from calcium spiking and root-hair deformation to the development of the nodule. Early stages of actinorhizal symbiosis were monitored at the transcriptional level to observe plant host responses to Frankia alni. Forty-two genes were significantly upregulated in inoculated compared with noninoculated roots. Most of these genes encode proteins involved in biological processes induced during microbial infection, such as oxidative stress or response to stimuli, but a large number of them are not differentially modulated or downregulated later in the process of nodulation. In contrast, several of them remained upregulated in mature nodules, and this included the gene most upregulated, which encodes a nonspecific lipid transfer protein (nsLTP). Classified as an antimicrobial peptide, this nsLTP was immunolocalized on the deformed root-hair surfaces that are points of contact for Frankia spp. during infection. Later in nodules, it binds to the surface of F. alni ACN14a vesicles, which are the specialized cells for nitrogen fixation. This nsLTP, named AgLTP24, was biologically produced in a heterologous host and purified for assay on F. alni ACN14a to identify physiological effects. Thus, the activation of the plant immunity response occurs upon first contact, while the recognition of F. alni ACN14a genes switches off part of the defense system during nodulation. AgLTP24 constitutes a part of the defense system that is maintained all along the symbiosis, with potential functions such as the formation of infection threads or nodule primordia to the control of F. alni proliferation. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Descriptions of Micromonospora grosourdyae nom. nov., Micromonospora sonchi comb. nov. and Micromonospora thawaii sp. nov. to resolve problems with the taxonomy and nomenclature of strains named Micromonospora endophytica.

The name Micromonospora endophytica has been used for three different organisms. The first organism with this name is the species represented by strain DCWR9-8-2T, a species published in 2015 but whose name was never validated. In 2019 the type species of the genus Jishengella was reclassified into the genus Micromonospora, while maintaining its original epithet, thus establishing the second group of organisms known as M. endophytica, but the first for which the name was validated. Additionally, in 2018 the reclassification of the genus Verrucosispora into the genus Micromonospora was proposed, but a new epithet has not been specified for the species named Verrucosispora endophytica, which remains an orphaned species. Therefore, it is necessary to propose new names that can unequivocally identify these taxa. We have analysed the taxonomic position of the strains, comparing them with the species with valid published names of the genus Micromonospora. We here propose Micromonospora thawaii sp. nov. for the species represented by strain DCWR9-8-2T, and Micromonospora grosourdyae nom. nov. and Micromonospora sonchi comb. nov. for the two orphaned species of Verrucosispora, V. endophytica and Verrucosispora sonchi, respectively. Genomic analysis also showed that M. trujilloniae is a later heterotypic synonym of M. andamanensis.

Rossellomorea arthrocnemi sp. nov., a novel plant growth-promoting bacterium used in heavy metal polluted soils as a phytoremediation tool.

Strain EAR8T is a root endophyte isolated from Arthrocnemum macrostachyum plants collected from the Odiel marshes, Huelva (Spain). It presented in vitro plant growth-promoting properties and improved the plant growth and heavy metal accumulation in polluted soils playing an important role in phytoremediation strategies. Phenotypically, strain EAR8T cells were Gram-positive, aerobic and non-motile rods with terminal oval endospores and non-swollen sporangia which form beige, opaque, butyrous, raised and irregular colonies with undulate margins. The strain was able to grow between 15-45 °C, at pH 6.0-9.0 and tolerated 0-25 % NaCl (w/v) showing optimal growth conditions on trypticase soy agar plates supplemented with 2.5 % NaCl (w/v) at pH 7.0 and 37 °C for 24 h. Chemotaxonomic analyses showed that the isolate has meso-diaminopimelic acid as the peptidoglycan in the cell wall and MK-7 as the major respiratory quinone. The predominant fatty acids were anteiso-C15 : 0 and iso-C15 : 0 and the polar lipid profile was composed of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phylogenetic analyses based on the whole proteomes of closest sequenced relatives confirmed that strain EAR8T is affiliated to the genus Rossellomorea and forms a clade with Rossellomorea vietnamensis 15-1T with maximum support. Genome analyses showed that EAR8T has indole-3-acetic acid and siderophore biosynthesis and transporters genes and genes related to resistance against heavy metals. Phenotypic and phylogenomic comparative studies suggested that strain EAR8T is a new representative of the genus Rossellomorea and the name Rossellomorea arthrocnemi sp. nov. is proposed. Type strain is EAR8T (=CECT 9072T=DSM 103900T).

Pseudoalteromonas rhizosphaerae sp. nov., a novel plant growth-promoting bacterium with potential use in phytoremediation.

Strain RA15T was isolated from the rhizosphere of the halophyte plant Arthrocnemum macrostachyum growing in the Odiel marshes (Huelva, Spain). RA15T cells were Gram stain-negative, non-spore-forming, aerobic rods and formed cream-coloured, opaque, mucoid, viscous, convex, irregular colonies with an undulate margin. Optimal growth conditions were observed on tryptic soy agar (TSA) plates supplemented with 2.5 % NaCl (w/v) at pH 7.0 and 28 °C, although it was able to grow at 4-32 °C and at pH values of 5.0-9.0. The NaCl tolerance range was from 0 to 15 %. The major respiratory quinone was Q8 but Q9 was also present. The most abundant fatty acids were summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C17 : 1 ω8c and C16 : 0. The polar lipids profile comprised phosphatidylglycerol and phosphatidylethanolamine as the most abundant representatives. Phylogenetic analyses confirmed the well-supported affiliation of strain RA15T within the genus Pseudoalteromonas, close to the type strains of Pseudoalteromonas neustonica, Pseudoalteromonas prydzensis and Pseudoalteromonas mariniglutinosa. Results of comparative phylogenetic and phenotypic studies between strain RA15T and its closest related species suggest that RA15T could be a new representative of the genus Pseudoalteromonas, for which the name Pseudoalteromonas rhizosphaerae sp. nov. is proposed. The type strain is RA15T (=CECT 9079T=LMG 29860T). The whole genome has 5.3 Mb and the G+C content is 40.4 mol%.

Halomonas radicis sp. nov., isolated from Arthrocnemum macrostachyum growing in the Odiel marshes(Spain) and emended descriptions of Halomonas xinjiangensis and Halomonas zincidurans.

Strain EAR18T was isolated as an endophyte from the roots of a halophyte plant, Arthrocnemum macrostachyum, growing in the Odiel marshes (Huelva, Spain). Cells of strain EAR18T were Gram- stain-negative, motile, non-spore-forming aerobic rods. It grew optimally on tryptic soy agar supplemented with 2.5 % NaCl (w/v), at pH 7 and 30 °C for 48 h. It tolerated NaCl from 0 to 25 % (w/v). It presented Q9 as the major quinone and C19 : 0 cyclo ω8c, summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0 as the predominant fatty acids. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and four unidentified phospholipids. The results of phylogenetic analysis based on 16S rRNA gene sequences revealed that strain EAR18T formed a well-supported clade with species Halomonas zincidurans B6T and Halomonas xinjiangensis TRM 0175T (similarities of 98.3 and 96.1 % respectively). Furthermore, digital DNA-DNA hybridization analysis resulted in values of 20.4 % with H. xinjiangensis TRM 0175T and 35.50 % with H. zincidurans B6T, and ANIb/ANIm results in values of 73.8 %/84.2 % with H. xinjiangensis TRM 0175T and 86.8 %/89.4 % with H. zincidurans B6T. Based on phylogeny and differential phenotypic properties in comparison with its closest related species, strain EAR18T is suggested to represent a new species in the genus Halomonas, for which the name Halomonas radicis sp. nov. is proposed. The type strain is EAR18T (=CECT 9077T=LMG 29859T). The whole genome was sequenced, and it had a total length of 4.6 Mbp and a G+C content of 64.9 mol%.

Micromonospora orduensis sp. nov., isolated from deep marine sediment.

A novel actinobacterial strain, designated S2509T, was isolated from marine sediment collected by a dredge at a depth of 45 m along Melet River offshore of the southern Black Sea coast, Ordu, Turkey. The cell wall peptidoglycan of strain was found to contain meso-diaminopimelic acid and 3-OH-diaminopimelic acid. The whole cell sugars detected were arabinose, glucose, rhamnose, ribose and xylose. The diagnostic phospholipids of strain S2509T were found to be diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, a glycolipid and two unidentified phospholipids. The predominant menaquinones were identified as MK-9(H8), MK-9(H6), MK-10(H8), MK-9(H4), MK-10(H4) and MK-10(H6). The major cellular fatty acids were found to be iso-C16:0, iso-C15:0 and 10-methyl C17:0. The taxonomic position of the strain was established using a polyphasic approach, showing that S2509T strain belongs to the genus Micromonospora. Phylogenetic analysis based on the 16S rRNA gene sequence of strain S2509T showed that it is closely related to the type strain of Micromonospora chokoriensis DSM 45160T (99.37% sequence similarity), and phylogenetically clustered with Micromonospora inaquosa LB39T (99.37%), Micromonospora lupini Lupac 14NT (99.16%), Micromonospora violae NEAU-zh8T (99.23%) and Micromonospora taraxaci NEAU-P5T (99.03%). The phylogenetic analysis based on the gyrB gene sequence of strain S2509T confirmed its close relationship with M. chokoriensis JCM 13247T (96.5% sequence similarity). Whole genome sequences confirmed by digital DNA-DNA hybridization analysis that the strain S2509T represents a novel species in the genus Micromonospora, for which the name Micromonospora orduensis sp. nov. is proposed. The type strain is S2509T (=DSM 45926T = KCTC 29201T).

Micromonospora acroterricola sp. nov., a novel actinobacterium isolated from a high altitude Atacama Desert soil.

A Micromonospora strain, designated 5R2A7T, isolated from a high altitude Atacama Desert soil was examined by using a polyphasic approach. Strain 5R2A7T was found to have morphological, chemotaxonomic and cultural characteristics typical of members of the genus Micromonospora. The cell wall contains meso- and hydroxy-diaminopimelic acid, the major whole-cell sugars are glucose, ribose and xylose, the predominant menaquinones MK-10(H4), MK-10(H6), MK-10(H8) and MK-9(H6), the major polar lipids diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and an unknown glycolipid, and the predominant cellular fatty acids iso-C16 : 0, iso-C15 : 0 and 10-methyl C17 : 0. The digital genomic DNA G+C content is 72.3 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain 5R2A7T was closely related to Micromonospora coriariae DSM 44875T (99.8 %) and Micromonospora cremea CR30T (99.7 %), and was separated readily from the latter, its closest phylogenetic neighbour, based on gyrB and multilocus sequence data, by low average nucleotide identity (92.59 %) and in silico DNA-DNA relatedness (51.7 %) values calculated from draft genome assemblies and by a range of chemotaxonomic and phenotypic properties. Consequently, strain 5R2A7T is considered to represent a novel species of Micromonospora for which the name Micromonospora acroterricola sp. nov. is proposed. The type strain is 5R2A7T (=LMG 30755T=CECT 9656T).

Jiangella anatolica sp. nov. isolated from coastal lake soil.

A novel actinobacterial strain, designated GTF31T, was isolated from a coastal soil sample of Gölcük Lake, a crater lake in southwest Anatolia, Turkey. The taxonomic position of the strain was established using a polyphasic approach. Phylogenetic analyses based on 16S rRNA gene sequences and showed that the strain is closely related to Jiangella gansuensis DSM 44835T (99.4%), Jiangella alba DSM 45237T (99.3%) and Jiangella muralis DSM 45357T (99.2%). Optimal growth was observed at 28 °C and pH 7-8. Whole cell hydrolysates were found to contain LL-DAP, glucose, mannose, rhamnose and ribose. The predominant menaquinone was identified as MK-9(H4). The polar lipid profile was found to contain diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, glycophospholipids and unidentified phospholipids. The major fatty acids were identified as anteiso-C15:0, iso-C16:0 and anteiso-C17:0. The G + C content of the type strain was determined to be 72.5% and the size of the draft genome is 7.0 Mb. The calculated digital DDH values between strain GTF31T and the type strains of J. gansuensis, J. alba, J. muralis and Jiangella alkaliphila ranged from 24.4 to 34.4% and ANI values ranged between 81.0 and 87.9%. Based upon the consensus of phenotypic and phylogenetic analyses as well as whole genome comparisons, strain GTF31T (= DSM 100984T = CECT 9378T) is proposed to represent the type strain of a novel species, Jiangella anatolica sp. nov.

Micromonospora phytophila sp. nov. and Micromonospora luteiviridis sp. nov., isolated as natural inhabitants of plant nodules.

Two actinobacterial isolates, strains SG15T and SGB14T, were recovered through a microbial diversity study of nitrogen fixing nodules from Pisum sativum plants collected in Salamanca (Spain). The taxonomic status of these isolates was determined using a polyphasic approach and both presented chemotaxonomic and morphological properties consistent with their classification in the genus Micromonospora. For strains SG15T and SGB14T, the highest 16S rRNA gene sequence similarities were observed with Micromonospora coxensis JCM 13248T (99.2 %) and Micromonospora purpureochromogenes DSM 43821T (99.4 %), respectively. However, strains SG15T and SGB14T were readily distinguished from their phylogenetic neighbours both genetically and phenotypically indicating that they represent two new Micromonospora species. The following names are proposed for these species: Micromonosporaphytophila sp. nov. type strain SG15T (=CECT 9369T; =DSM 105363T), and Micromonosporaluteiviridis sp. nov. type strain SGB14T (=CECT 9370T; =DSM 105362T).

Kushneria phyllosphaerae sp. nov. and Kushneria endophytica sp. nov., plant growth promoting endophytes isolated from the halophyte plant Arthrocnemum macrostachyum.

Two endophytic bacteria (EAod3T and EAod7T) were isolated from the aerial part of plants of Arthrocnemum macrostachyum growing in the Odiel marshes (Huelva, Spain). Phylogenetic analysis based on 16S rRNA gene sequences indicated their affiliation to the genus Kushneria. 16S rRNA gene sequences of strains EAod3T and EAod7T showed the highest similarity to Kushneria marisflavi DSM 15357T (99.0 and 97.6 %, respectively). Digital DNA-DNA hybridization studies between the draft genomes of strain EAod3T and K. marisflavi DSM 15357T corresponded to 28.5 % confirming the novel lineage of strain EAod3T in the genus Kushneria. Cells of both strains were Gram-staining-negative, aerobic and motile rods able to grow at 4-37 °C, at pH 5.0-8.0 and tolerate 0.5-25 % NaCl (w/v). They presented ubiquinone Q9 and C16 : 0, C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω7c as the major fatty acids. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Based on the phenotypic and phylogenetic results, strains EAod3T (=CECT 9073T=LMG 29856T) and EAod7T (=CECT 9075T=LMG 29858T) are proposed as new representatives of the genus Kushneria, and the proposed names are Kushneria phyllosphaerae sp. nov. and Kushneria endophytica sp. nov., respectively. The whole genome sequence of strain EAod3T has a total length of 3.8 Mbp and a G+C content of 59.3 mol%.

Formal description of Mycobacterium neglectum sp. nov. and Mycobacterium palauense sp. nov., rapidly growing actinobacteria.

The taxonomic positions of two fast growing mycobacteria (CECT 8778T and CECT 8779T) were established using a polyphasic approach. The strains were shown to have chemotaxonomic, cultural and morphological properties consistent with their classification in the genus Mycobacterium. Multi-locus sequence analyses (MLSA) show that strain CECT 8778T forms a well-supported clade together with the type strains of Mycobacterium aurum, Mycobacterium austroafricanum and Mycobacterium vanbaalenii while strain CECT 8779T presents as a distinct branch that is well separated from its near phylogenetic neighbours; it is also apparent from the MLSA genetic distances that these strains are most closely related to the type strains of Mycobacterium mageritense and M. vanbaalenii, respectively. Digital DNA:DNA hybridization and average nucleotide identity values between each of the strains and its close phylogenetic neighbour are below the 70 and 96% threshold values for definition of prokaryotic species; these results are underpinned by corresponding phenotypic data. Based upon the consensus of the phenotypic and phylogenetic analyses, it can be concluded that the two strains represent novel species within the genus Mycobacterium for which the following names are proposed: Mycobacterium neglectum sp. nov., with the type strain CECT 8778T (BN 3150T = DSM 44756T) and Mycobacterium palauense sp. nov., with the type strain CECT 8779T (= DSM 44914T).

Hunting for cultivable Micromonospora strains in soils of the Atacama Desert.

Innovative procedures were used to selectively isolate small numbers of Micromonospora strains from extreme hyper-arid and high altitude Atacama Desert soils. Micromonosporae were recognised on isolation plates by their ability to produce filamentous microcolonies that were strongly attached to the agar. Most of the isolates formed characteristic orange colonies that lacked aerial hyphae and turned black on spore formation, whereas those from the high altitude soil were dry, blue-green and covered by white aerial hyphae. The isolates were assigned to seven multi- and eleven single-membered groups based on BOX-PCR profiles. Representatives of the groups were assigned to either multi-membered clades that also contained marker strains or formed distinct phyletic lines in the Micromonospora 16S rRNA gene tree; many of the isolates were considered to be putatively novel species of Micromonospora. Most of the isolates from the high altitude soils showed activity against wild type strains of Bacillus subtilis and Pseudomonas fluorescens while those from the rhizosphere of Parastrephia quadrangulares and from the Lomas Bayas hyper-arid soil showed resistance to UV radiation.

Delftia rhizosphaerae sp. nov. isolated from the rhizosphere of Cistus ladanifer.

A bacterial strain, designated RA6T, was isolated from the rhizosphere of Cistus ladanifer. Phylogenetic analyses based on 16S rRNA gene sequence placed the isolate into the genus Delftia within a cluster encompassing the type strains of Delftia lacustris, Delftia tsuruhatensis, Delftia acidovorans and Delftia litopenaei, which presented greater than 97 % sequence similarity with respect to strain RA6T. DNA-DNA hybridization studies showed average relatedness ranging from of 11 to 18 % between these species of the genus Delftia and strain RA6T. Catalase and oxidase were positive. Casein was hydrolysed but gelatin and starch were not. Ubiquinone 8 was the major respiratory quinone detected in strain RA6T together with low amounts of ubiquinones 7 and 9. The major fatty acids were those from summed feature 3 (C16 : 1ω7c/C16 : 1 ω6c) and C16 : 0. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain RA6T should be considered as a representative of a novel species of genus Delftia, for which the name Delftia rhizosphaerae sp. nov. is proposed. The type strain is RA6T (=LMG 29737T= CECT 9171T).

Mycobacterium eburneum sp. nov., a non-chromogenic, fast-growing strain isolated from sputum.

A polyphasic study was undertaken to establish the taxonomic position of a non-chromogenic, rapidly growing Mycobacterium strain that had been isolated from sputum. The strain, CECT 8775T, has chemotaxonomic and cultural properties consistent with its classification in the genus Mycobacterium and was distinguished from the type strains of closely related mycobacterial species, notably from Mycobacterium paraense DSM 46749T, its nearest phylogenetic neighbour, based on 16S rRNA, hsp65 and rpoB gene sequence data. These organisms were also distinguished by a broad range of chemotaxonomic and phenotypic features and by a digital DNA-DNA relatedness value of 22.8 %. Consequently, the strain is considered to represent a novel species of Mycobacterium for which the name Mycobacterium eburneum sp. nov is proposed; the type strain is X82T (CECT 8775T=DSM 44358T).

Two novel species of rapidly growing mycobacteria: Mycobacterium lehmannii sp. nov. and Mycobacterium neumannii sp. nov.

Two rapidly growing mycobacteria with identical 16S rRNA gene sequences were the subject of a polyphasic taxonomic study. The strains formed a well-supported subclade in the mycobacterial 16S rRNA gene tree and were most closely associated with the type strain of Mycobacterium novocastrense. Single and multilocus sequence analyses based on hsp65, rpoB and 16S rRNA gene sequences showed that strains SN 1900T and SN 1904T are phylogenetically distinct but share several chemotaxonomic and phenotypic features that are are consistent with their classification in the genus Mycobacterium. The two strains were distinguished by their different fatty acid and mycolic acid profiles, and by a combination of phenotypic features. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values for strains SN 1900T and SN 1904T were 61.0 % and 94.7 %, respectively; in turn, the corresponding dDDH and ANI values with M. novocastrense DSM 44203T were 41.4 % and 42.8 % and 89.3 % and 89.5 %, respectively. These results show that strains SN1900T and SN 1904T form new centres of taxonomic variation within the genus Mycobacterium. Consequently, strains SN 1900T (40T=CECT 8763T=DSM 43219T) and SN 1904T (2409T=CECT 8766T=DSM 43532T) are considered to represent novel species, for which the names Mycobacteriumlehmannii sp. nov. and Mycobacteriumneumannii sp. nov. are proposed. A strain designated as 'Mycobacteriumacapulsensis' was shown to be a bona fide member of the putative novel species, M. lehmannii.

Brevundimonas canariensis sp. nov., isolated from roots of Triticum aestivum.

A bacterial strain designated GTAE24T was isolated from a root of wheat growing in soil from the Canary Islands, Spain. Phylogenetic analyses based on 16S rRNA gene sequences placed the isolate in the genus Brevundimonas with Brevundimonas abyssalisTAR-001T as its closest relative at 99.4 % similarity. DNA-DNA hybridization studies showed an average of 38 % relatedness between strain GTAE24T and the type strain of B. abyssalis. Cells were Gram-stain-negative and motile by polar flagella. The strain was positive for oxidase and weakly positive for catalase. Gelatin, starch and casein were not hydrolysed. Growth was supported by many carbohydrates and organic acids as carbon source. Ubiquinone Q-10 was the predominant isoprenoid quinone and C18 : 1ω7c/C18 : 1ω6c (summed feature 8) and C16 : 0 were the major fatty acids. The major polar lipids were phosphatidylglycerol, 1,2-di-O-acyl-3-O-[d-glucopyranosyl-(1,4)-α-d-glucopyranuronosyl] glycerol, 1,2-diacyl-3-O-[6'-phosphatidyl-α-d-glucopyranosyl] glycerol, 1,2-di-O-acyl-3-O-α-d-glucopyranosyl glycerol, and 1,2-di-O-acyl-3-O-α-d-glucopyranuronosyl glycerol. The DNA G+C content was 63.9 mol%. Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain GTAE24T should be considered as representing a novel species of the genus Brevundimonas, for which the name Brevundimonas canariensis sp. nov. is proposed. The type strain is GTAE24T (=LMG 29500T=CECT 9126T).

Actinomadura alkaliterrae sp. nov., isolated from an alkaline soil.

A polyphasic study was undertaken to establish the taxonomic status of an Actinomadura strain isolated from the margin of a saline, alkaline lake in Central Anatolia, Turkey. Strain D310ATT was shown to have chemotaxonomic, cultural and morphological properties consistent with its classification in the genus Actinomadura such as hooked or irregular spiral spore chains, meso-diaminopimelic acid as the major cell wall diaminopimelic acid, and diphosphatidylglycerol and phosphatidylinositol as major polar lipids. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain D310ATT is closely, albeit loosely, associated with Actinomadura darangshiensis DLS-70T with 97.2% sequence similarity, but was readily separated from the latter using diverse phenotypic properties. Consequently, the isolate is considered to represent a new species of Actinomadura for which the name Actinomadura alkaliterrae sp. nov. is proposed, with the type strain D310ATT (=DSM 101185T = KCTC 39657T).