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Several strains were isolated from subsurface soil of the Atacama Desert and were previously assigned to the Micromonospora genus. A polyphasic study was designed to determine the taxonomic affiliation of isolates 4G51 T , 4G53, and 4G57. All the strains showed chemotaxonomic properties in line with their classification in the genus Micromonospora, including meso-diaminopimelic acid in the cell wall peptidoglycan, MK-9(H 4 ) as major respiratory quinone, iso-C 15:0 and iso-C 16:0 as major fatty acids and diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol as major polar lipids. The 16S rRNA gene sequences of strains 4G51 T , 4G53, and 4G57 showed the highest similarity (97.9 %) with the type strain of Micromonospora costi CS1-12 T , forming an independent branch in the phylogenetic gene tree. Their independent position was confirmed with genome phylogenies, being most closely related to the type strain of Micromonospora kangleipakensis. Digital DNA-DNA hybridization and average nucleotide identity analyses between the isolates and their closest phylogenomic neighbours confirmed that they should be assigned to a new species within the genus Micromonospora for which the name Micromonospora sicca sp. nov. (4G51 T =PCM 3031 T =LMG 30756 T ) is proposed., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier GmbH.. All rights reserved.)

Two novel Micromonospora strains, STR1-7 T and STR1S-6 T , 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 STR1-7 T is most closely related to Micromonospora orduensis S2509 T , 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 STR1-7 T and STR1S-6 T 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 STR1-7 T (=CECT 9665 T =LMG 30768 T ) and STR1S-6 T (=CECT 9666 T =LMG 30770 T ), 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.

Four Gram-positive, aerobic, catalase- and oxidase-negative, rod-shaped, motile endophytic bacterial strains, designated NM3R9 T , NE1TT3, NE2TL11 and NE2HP2 T , 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 NE2HP2 T was Microbacterium arborescens DSM 20754 T (99.6 %) and that closest to NM3R9 T , NE2TL11 and NE2TT3 was Microbacterium oleivorans NBRC 103075 T (97.4 %). The whole-genome average nucleotide identity value between strain NM3R9 T and Microbacterium imperiale DSM 20530 T was 90.91 %, and that between strain NE2HP2 T and M. arborecens DSM 20754 T 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-C 15 : 0 , anteiso-C 17 : 0 , iso-C 16 : 0 and C 16 : 0 . Whole-cell sugars included mannose, rhamnose and galactose. Strains NM3R9 T and NE2HP2 T 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 NE2HP2 T (=LMG 30875 T =CCBAU 101117 T ) and Microbacterium thalli sp. nov. for strains NM3R9 T (=LMG 30873 T =CCBAU 101116 T ), NE1TT3 (=CCBAU 101114) and NE2TL11 (=CCBAU 101115).

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 CO 2 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. CO 2 levels in N 2 -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 NH 4 + . 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 NH 3 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.

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.

The name Micromonospora endophytica has been used for three different organisms. The first organism with this name is the species represented by strain DCWR9-8-2 T , 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 DCWR9-8-2 T , 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 .

Tendinopathy is labeled by many authors as a troublesome, common pathology, present in up to 30% medical care consultations involving musculoskeletal conditions. Despite the lasting interest for addressing tendon pathology, current researchers agree that even the exact definition of the term tendinopathy is unclear. Tendinopathy is currently diagnosed as a clinical hypothesis based on the patient symptoms and physical context. One of the main goals of current clinical management is to personalize treatment approaches to adapt them to the many different needs of the population. Tendons are complex structures that unite muscles and bones with two main objectives: to transmit forces and storage and release energy. Regarding the tensile properties of the tendons, several authors argued that tendons have higher tensile strength compared with muscles, however, are considered less flexible. Tendinopathy is an accepted term which is used to indicated a variety of tissue conditions that appear in injured tendons and describes a non-rupture damage in the tendon or paratendon, which is intensified with mechanical loading Even when the pathoetiology of tendinopathy is unclear, there is a wide array of treatments available to treat and manage tendinopathy. Although tendinitis usually debuts with an inflammatory response, the majority of chronic tendinopathies do not present inflammation and so the choosing of treatment should vary depending on severity, compliance, pain and duration of symptoms. The purpose of this article is to review and provide an overview about the currently research of the tendon diagnosis, management and etiology., Competing Interests: Conflicts of Interest There are no conflicts of interest., (Copyright © 2021. Published by Elsevier Inc.)

The present study aimed to compare by ultrasound imaging (USI) the tibial posterior (TP), medial gastrocnemius (MG) and soleus muscle in patients with and without plantar fasciitis (PF). A sample of 42 individuals was recruited and divided into two groups: PF and a healthy group. The thickness, cross-sectional area (CSA), echointensity and echovariation were assessed in both groups by USI. TP, soleus and MG variables did not report differences (p > 0.05) for thickness and CSA. For the echotexture parameters significant differences were found for MG echointensity (p = 0.002), MG echovariation (p = 0.002) and soleus echointensity (p = 0.012). Non-significant differences (p > 0.05) were reported for soleus echovariation, TP echointensity and TP echovariation variables. The thickness and CSA of the TP, GM and soleus muscle did not show significant differences between individuals with and without PF measured by USI. Muscle quality assessment reported an increase of the MG echointensity and echovariation, as well as a decrease of echointensity of the soleus muscle in the PF group with respect to the healthy group. Therefore, the evaluation of the structure and muscle quality of the extrinsic foot muscles may be beneficial for the diagnosis and monitoring the physical therapy interventions.

Objective: The primary aim of the present study was to compare the echo intensity (EI) and echovariation (EV) of the intrinsic foot muscles (IFMs) between individuals with and without plantar fasciitis (PF), using ultrasound imaging. The secondary objective was to study the intra-rater reliability of the echotexture variables. Methods: A case−control study was conducted with 64 participants, who were divided into the following two groups: A, the PF group (n = 32); B, the healthy group (n = 32). Results: The comparison between the two groups did not identify significant differences (p > 0.05) between the flexor hallucis brevis (FHB), flexor digitorum brevis (FDB), quadratus plantae (QP) and abductor hallucis brevis (AHB) variables for the EI and EV. Moreover, excellent intra-rater reliability was reported for the following ultrasound imaging EI variables: ABH (ICC = 0.951), FHB (ICC = 0.949), FDB (ICC = 0.981) and QP (ICC = 0.984). Conclusions: The muscle quality assessment using the EI and EV variables did not identify differences in the FHB, FDB, AHB and QP muscles between individuals with and without PF through USI evaluation. The reliability of all the IFM measurements was reported to be excellent.

Strain EAR8 T 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 EAR8 T 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-C 15 : 0 and iso-C 15 : 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 EAR8 T is affiliated to the genus Rossellomorea and forms a clade with Rossellomorea vietnamensis 15-1 T with maximum support. Genome analyses showed that EAR8 T 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 EAR8 T is a new representative of the genus Rossellomorea and the name Rossellomorea arthrocnemi sp. nov. is proposed. Type strain is EAR8 T (=CECT 9072 T =DSM 103900 T ).

Pisum sativum L. (pea) is one of the most cultivated grain legumes in European countries due to the high protein content of its seeds. Nevertheless, the rhizobial microsymbionts of this legume have been scarcely studied in these countries. In this work, we analyzed the rhizobial strains nodulating the pea in a region from Northwestern Spain, where this legume is widely cultivated. The isolated strains were genetically diverse, and the phylogenetic analysis of core and symbiotic genes showed that these strains belong to different clusters related to R. laguerreae sv. viciae. Representative strains of these clusters were able to produce cellulose and cellulases, which are two key molecules in the legume infection process. They formed biofilms and produced acyl-homoserine lactones (AHLs), which are involved in the quorum sensing regulation process. They also exhibited several plant growth promotion mechanisms, including phosphate solubilization, siderophore, and indole acetic acid production and symbiotic atmospheric nitrogen fixation. All strains showed high symbiotic efficiency on pea plants, indicating that strains of R. laguerreae sv. viciae are promising candidates for the biofertilization of this legume worldwide.

Heavy metal pollution in the environment is an increasing problem due to natural and anthropogenic activities. The use of bacteria for bioremediation of soils contaminated with heavy metals has gained a lot of attention as it can be considered effective, economic and environmentally sustainable. In this work, we investigated the capacity of endophytic Micromonospora strains isolated from different legumes, to produce metallophores against a variety of heavy metals in vitro. Genome mining using available endophytic Micromonospora genome sequences revealed the presence of genes related to metal acquisition, iron metabolism and resistance to toxic compounds. In vitro production of metallophores demonstrated that all strains tested produced chelates against arsenic, cobalt, copper, chromium, iron, mercury, molybdenum, nickel, vanadium and zinc in different amounts. In addition, the plant growth promotion effect of strains GAR05 and PSN13 on Arabidopsis thaliana grown in the presence of several heavy metals was tested. Under these conditions, the plants inoculated with the strain GAR05 showed significant growth when compared to the control plants suggesting a plant growth promotion effect in the form of tolerance to the toxic substances. Furthermore, during this plant-bacterium interaction, a new bacterial structure named root-bead was observed on the roots of A. thaliana suggesting a strong interaction between the two organisms and a clear positive effect of the bacterium on the plant. Overall, these results highlight the potential use of endophytic Micromonospora strains for bacterial-assisted phytoremediation of contaminated sites., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Strain RA15 T was isolated from the rhizosphere of the halophyte plant Arthrocnemum macrostachyum growing in the Odiel marshes (Huelva, Spain). RA15 T 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 (C 16 : 1   ω7 c and/or C 16 : 1   ω6 c ), C 17 : 1  ω 8 c and C 16 : 0 . The polar lipids profile comprised phosphatidylglycerol and phosphatidylethanolamine as the most abundant representatives. Phylogenetic analyses confirmed the well-supported affiliation of strain RA15 T 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 RA15 T and its closest related species suggest that RA15 T could be a new representative of the genus Pseudoalteromonas , for which the name Pseudoalteromonas rhizosphaerae sp. nov. is proposed. The type strain is RA15 T (=CECT 9079 T =LMG 29860 T ). The whole genome has 5.3 Mb and the G+C content is 40.4 mol%.

A novel actinobacterial strain, designated S2509 T , 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 S2509 T were found to be diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, a glycolipid and two unidentified phospholipids. The predominant menaquinones were identified as MK-9(H 8 ), MK-9(H 6 ), MK-10(H 8 ), MK-9(H 4 ), MK-10(H 4 ) and MK-10(H 6 ). The major cellular fatty acids were found to be iso-C 16:0 , iso-C 15:0 and 10-methyl C 17:0 . The taxonomic position of the strain was established using a polyphasic approach, showing that S2509 T strain belongs to the genus Micromonospora. Phylogenetic analysis based on the 16S rRNA gene sequence of strain S2509 T showed that it is closely related to the type strain of Micromonospora chokoriensis DSM 45160 T (99.37% sequence similarity), and phylogenetically clustered with Micromonospora inaquosa LB39 T (99.37%), Micromonospora lupini Lupac 14N T (99.16%), Micromonospora violae NEAU-zh8 T (99.23%) and Micromonospora taraxaci NEAU-P5 T (99.03%). The phylogenetic analysis based on the gyrB gene sequence of strain S2509 T confirmed its close relationship with M. chokoriensis JCM 13247 T (96.5% sequence similarity). Whole genome sequences confirmed by digital DNA-DNA hybridization analysis that the strain S2509 T represents a novel species in the genus Micromonospora, for which the name Micromonospora orduensis sp. nov. is proposed. The type strain is S2509 T (=DSM 45926 T  = KCTC 29201 T ).

Strain EAR18 T was isolated as an endophyte from the roots of a halophyte plant, Arthrocnemum macrostachyum , growing in the Odiel marshes (Huelva, Spain). Cells of strain EAR18 T 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 C 19 : 0 cyclo ω 8 c , summed feature 8 (C 18 : 1 ω7 c and/or C 18 : 1 ω6 c ) and C 16 : 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 EAR18 T formed a well-supported clade with species Halomonas zincidurans B6 T and Halomonas xinjiangensis TRM 0175 T (similarities of 98.3 and 96.1 % respectively). Furthermore, digital DNA-DNA hybridization analysis resulted in values of 20.4 % with H. xinjiangensis TRM 0175 T and 35.50 % with H. zincidurans B6 T , and ANIb/ANIm results in values of 73.8 %/84.2 % with H. xinjiangensis TRM 0175 T and 86.8 %/89.4 % with H. zincidurans B6 T . Based on phylogeny and differential phenotypic properties in comparison with its closest related species, strain EAR18 T 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 EAR18 T (=CECT 9077 T =LMG 29859 T ). The whole genome was sequenced, and it had a total length of 4.6 Mbp and a G+C content of 64.9 mol%.

A Micromonospora strain, designated 5R2A7 T , isolated from a high altitude Atacama Desert soil was examined by using a polyphasic approach. Strain 5R2A7 T 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(H 4 ), MK-10(H 6 ), MK-10(H 8 ) and MK-9(H 6 ), the major polar lipids diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and an unknown glycolipid, and the predominant cellular fatty acids iso -C 16 : 0 , iso -C 15 : 0 and 10-methyl C 17 : 0 . The digital genomic DNA G+C content is 72.3 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain 5R2A7 T was closely related to Micromonospora coriariae DSM 44875 T (99.8 %) and Micromonospora cremea CR30 T (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 5R2A7 T is considered to represent a novel species of Micromonospora for which the name Micromonospora acroterricola sp. nov. is proposed. The type strain is 5R2A7 T (=LMG 30755 T =CECT 9656 T ).

Three actinomycete strains, designated BL1, BL4, and CV4, were isolated from sediment samples from the Gulf of California in 2009 together with nearly 300 other actinobacteria. Genome mining and analysis of their ∼6.4-Mb sequences confirmed the bioprospecting potential of these three bacteria belonging to the genus Micromonospora ., (Copyright © 2019 Contreras-Castro et al.)

This study was designed to determine the plant growth promoting (PGP) potential of members of the genus Frankia . To this end, the genomes of 21 representative strains were examined for genes associated directly or indirectly with plant growth. All of the Frankia genomes contained genes that encoded for products associated with the biosynthesis of auxins [indole-3-glycerol phosphate synthases, anthranilate phosphoribosyltransferases ( trp D), anthranilate synthases, and aminases ( trp A and B)], cytokinins (11 well-conserved genes within the predicted biosynthetic gene cluster), siderophores, and nitrogenases ( nif operon except for atypical Frankia ) as well as genes that modulate the effects of biotic and abiotic environmental stress (e.g., alkyl hydroperoxide reductases, aquaporin Z, heat shock proteins). In contrast, other genes were associated with strains assigned to one or more of four host-specific clusters. The genes encoding for phosphate solubilization (e.g., low-affinity inorganic phosphate transporters) and lytic enzymes (e.g., cellulases) were found in Frankia cluster 1 genomes, while other genes were found only in cluster 3 genomes (e.g., alkaline phosphatases, extracellular endoglucanases, pectate lyases) or cluster 4 and subcluster 1c genomes (e.g., NAD(P) transhydrogenase genes). Genes encoding for chitinases were found only in the genomes of the type strains of Frankia casuarinae , F. inefficax , F. irregularis , and F. saprophytica . In short, these in silico genome analyses provide an insight into the PGP abilities of Frankia strains of known taxonomic provenance. This is the first study designed to establish the underlying genetic basis of cytokinin production in Frankia strains. Also, the discovery of additional genes in the biosynthetic gene cluster involved in cytokinin production opens up the prospect that Frankia may have novel molecular mechanisms for cytokinin biosynthesis.

A novel actinobacterial strain, designated GTF31 T , 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 44835 T (99.4%), Jiangella alba DSM 45237 T (99.3%) and Jiangella muralis DSM 45357 T (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(H 4 ). The polar lipid profile was found to contain diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, glycophospholipids and unidentified phospholipids. The major fatty acids were identified as anteiso-C 15:0 , iso-C 16:0 and anteiso-C 17:0 . 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 GTF31 T 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 GTF31 T (= DSM 100984 T  = CECT 9378 T ) is proposed to represent the type strain of a novel species, Jiangella anatolica sp. nov.

The taxonomic status, biotechnological and ecological potential of several Micromonospora strains isolated from an extreme hyper arid Atacama Desert soil were determined. Initially, a polyphasic study was undertaken to clarify the taxonomic status of five micromonosporae, strains LB4, LB19, LB32 T , LB39 T and LB41, isolated from an extreme hyper-arid soil collected from one of the driest regions of the Atacama Desert. All of the isolates were found to have chemotaxonomic, cultural and morphological properties consistent with their classification in the genus Micromonospora. Isolates LB32 T and LB39 T were distinguished from their nearest phylogenetic neighbours and proposed as new species, namely as Micromonospora arida sp. nov. and Micromonospora inaquosa sp. nov., respectively. Eluted methanol extracts of all of the isolates showed activity against a panel of bacterial and fungal indicator strains, notably against multi-drug resistant Klebsiella pneumoniae ATCC 700603 while isolates LB4 and LB41 showed pronounced anti-tumour activity against HepG2 cells. Draft genomes generated for the isolates revealed a rich source of novel biosynthetic gene clusters, some of which were unique to individual strains thereby opening up the prospect of selecting especially gifted micromonosporae for natural product discovery. Key stress-related genes detected in the genomes of all of the isolates provided an insight into how micromonosporae adapt to the harsh environmental conditions that prevail in extreme hyper-arid Atacama Desert soils.

During a study looking for the isolation of new actinobacteria strains with potential for antibiotic production from deep marine sediment, three strains were collected with a morphology similar to the one described for the Micromonospora genus. A polyphasic study was designed to determine the taxonomic affiliation of the strains S2901 T , S2903, and S2904. All the strains showed chemotaxonomic properties in line with their classification in the genus Micromonospora, meso-diaminopimelic acid in the wall peptidoglycan, a tetrahydrogenated menaquinone with nine isoprene units as major respiratory quinone, iso-C 15:0 and iso-C 16:0 as major fatty acids and diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol as major polar lipids. The 16S rRNA gene sequences of strain S2901 T , S2903, and S2904 showed the highest similarity (99.2%) with the type strain of Micromonospora halophytica DSM 43171 T , forming an independent branch in the phylogenetic gene tree. Their independent position was confirmed with gyrB gene and MLSA phylogenies. Whole genome sequences confirmed by digital DNA-DNA hybridization analysis that the isolates should be assigned to a new species within the genus Micromonospora for which the name Micromonospora globispora sp. nov. (S2901 T , S2903 and S2904) is proposed., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Two endophytic bacteria (EAod3 T and EAod7 T ) 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 EAod3 T and EAod7 T 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 EAod3 T and K. marisflavi DSM 15357 T corresponded to 28.5 % confirming the novel lineage of strain EAod3 T 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 EAod3 T (=CEC T 9073 T =LMG 29856 T ) and EAod7 T (=CECT 9075 T =LMG 29858 T ) 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 EAod3 T has a total length of 3.8 Mbp and a G+C content of 59.3 mol%.

The application of phylogenetic taxonomic procedures led to improvements in the classification of bacteria assigned to the phylum Actinobacteria but even so there remains a need to further clarify relationships within a taxon that encompasses organisms of agricultural, biotechnological, clinical, and ecological importance. Classification of the morphologically diverse bacteria belonging to this large phylum based on a limited number of features has proved to be difficult, not least when taxonomic decisions rested heavily on interpretation of poorly resolved 16S rRNA gene trees. Here, draft genome sequences of a large collection of actinobacterial type strains were used to infer phylogenetic trees from genome-scale data using principles drawn from phylogenetic systematics. The majority of taxa were found to be monophyletic but several orders, families, and genera, as well as many species and a few subspecies were shown to be in need of revision leading to proposals for the recognition of 2 orders, 10 families, and 17 genera, as well as the transfer of over 100 species to other genera. In addition, emended descriptions are given for many species mainly involving the addition of data on genome size and DNA G+C content, the former can be considered to be a valuable taxonomic marker in actinobacterial systematics. Many of the incongruities detected when the results of the present study were compared with existing classifications had been recognized from 16S rRNA gene trees though whole-genome phylogenies proved to be much better resolved. The few significant incongruities found between 16S/23S rRNA and whole genome trees underline the pitfalls inherent in phylogenies based upon single gene sequences. Similarly good congruence was found between the discontinuous distribution of phenotypic properties and taxa delineated in the phylogenetic trees though diverse non-monophyletic taxa appeared to be based on the use of plesiomorphic character states as diagnostic features.

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.

The taxonomic positions of two fast growing mycobacteria (CECT 8778 T and CECT 8779 T ) 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 8778 T forms a well-supported clade together with the type strains of Mycobacterium aurum, Mycobacterium austroafricanum and Mycobacterium vanbaalenii while strain CECT 8779 T 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 8778 T (BN 3150 T  = DSM 44756 T ) and Mycobacterium palauense sp. nov., with the type strain CECT 8779 T (= DSM 44914 T ).

The type isolates of species Micromonospora saelicesensis and Micromonospora noduli are Gram-stain positive actinobacteria that were originally isolated from nitrogen fixing nodules of the legumes Lupinus angustifolius and Pisum sativum , respectively. These two species are very closely related and questions arise as to whether they should be merged into a single species. To better delineate the relationship of M. saelicesensis and M. noduli , 10 strains isolated from plant tissue (nodules and leaves) and identified by their 16S rRNA gene sequences as either M. saelicensesis or M. noduli , based on a cut-off value of ≥99.5% were selected for whole-genome sequencing and compared with the type strains of M. saelicesensis Lupac 09 T and M. noduli GUI43 T using overall genome relatedness indices (OGRI) which included ANI, OrthoANI and digital DNA-DNA hybridization. Whole- and core-genome phylogenomic analyses were also carried out. These results were compared with the topologies of the 16S rRNA and gyrB gene phylogenies. Good correlation was found between all trees except for the 16S rRNA gene. Overall results also supported the current classification of M. saelicesensis and M. noduli as separate species. Especially useful was the core-genome phylogenetic analyses based on 92 genes and the dDDH results which were highly correlated. The importance of using more than one strain for a better definition of a species was also shown. A series of in vitro phenotypic assays performed at different times were compared with in silico predictions based on genomic data. In vitro phenotypic tests showed discrepancies among the independent studies, confirming the lack of reproducibility even when tests were performed in the same laboratory. On the other hand, the use of in silico predictions proved useful for defining a stable phenotype profile among the strains analyzed. These results provide a working framework for defining Micromonospora species at the genomic and phenotypic level.

There is a need to clarify relationships within the actinobacterial genus Micromonospora, the type genus of the family Micromonosporaceae, given its biotechnological and ecological importance. Here, draft genomes of 40 Micromonospora type strains and two non-type strains are made available through the Genomic Encyclopedia of Bacteria and Archaea project and used to generate a phylogenomic tree which showed they could be assigned to well supported phyletic lines that were not evident in corresponding trees based on single and concatenated sequences of conserved genes. DNA G+C ratios derived from genome sequences showed that corresponding data from species descriptions were imprecise. Emended descriptions include precise base composition data and approximate genome sizes of the type strains. antiSMASH analyses of the draft genomes show that micromonosporae have a previously unrealised potential to synthesize novel specialized metabolites. Close to one thousand biosynthetic gene clusters were detected, including NRPS, PKS, terpenes and siderophores clusters that were discontinuously distributed thereby opening up the prospect of prioritising gifted strains for natural product discovery. The distribution of key stress related genes provide an insight into how micromonosporae adapt to key environmental variables. Genes associated with plant interactions highlight the potential use of micromonosporae in agriculture and biotechnology.

Two actinobacterial isolates, strains SG15 T and SGB14 T , 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 SG15 T and SGB14 T , the highest 16S rRNA gene sequence similarities were observed with Micromonospora coxensis JCM 13248 T (99.2 %) and Micromonospora purpureochromogenes DSM 43821 T (99.4 %), respectively. However, strains SG15 T and SGB14 T 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 SG15 T (=CECT 9369 T ; =DSM 105363 T ), and Micromonosporaluteiviridis sp. nov. type strain SGB14 T (=CECT 9370 T ; =DSM 105362 T ).

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 1900 T and SN 1904 T 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 1900 T and SN 1904 T were 61.0 % and 94.7 %, respectively; in turn, the corresponding dDDH and ANI values with M. novocastrense DSM 44203 T were 41.4 % and 42.8 % and 89.3 % and 89.5 %, respectively. These results show that strains SN1900 T and SN 1904 T form new centres of taxonomic variation within the genus Mycobacterium. Consequently, strains SN 1900 T (40 T =CECT 8763 T =DSM 43219 T ) and SN 1904 T (2409 T =CECT 8766 T =DSM 43532 T ) 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.

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).

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).

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 D310AT T 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 D310AT T is closely, albeit loosely, associated with Actinomadura darangshiensis DLS-70 T 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 D310AT T (=DSM 101185 T  = KCTC 39657 T ).

Recent decades have predicted significant changes within our concept of plant endophytes, from only a small number specific microorganisms being able to colonize plant tissues, to whole communities that live and interact with their hosts and each other. Many of these microorganisms are responsible for health status of the plant, and have become known in recent years as plant probiotics. Contrary to human probiotics, they belong to many different phyla and have usually had each genus analysed independently, which has resulted in lack of a complete taxonomic analysis as a group. This review scrutinizes the plant probiotic concept, and the taxonomic status of plant probiotic bacteria, based on both traditional and more recent approaches. Phylogenomic studies and genes with implications in plant-beneficial effects are discussed. This report covers some representative probiotic bacteria of the phylum Proteobacteria , Actinobacteria , Firmicutes and Bacteroidetes , but also includes minor representatives and less studied groups within these phyla which have been identified as plant probiotics., Competing Interests: Conflict of Interest: All authors declare no conflicts of interest in this paper.

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).

A bacterial strain designated AMTAE16T was isolated from a root of wheat in Spain. Phylogenetic analyses based on 16S rRNA gene sequences placed the isolate in the genus Paenibacilluswith its closest relative being Paenibacillus daejeonensis AP-20T with 99.0 % 16S rRNA gene sequence similarity. DNA-DNA hybridization studies showed a mean of 30 % DNADNA relatedness between strain AMTAE16T and the type strain of P. daejeonensis. The isolate was a Gram-stainvariable, motile and sporulating rod. Catalase and oxidase activities were positive. Gelatin and starch were hydrolysed but not casein. Growth was supported by many carbohydrates and organic acids as carbon source. MK-7 was the only menaquinone detected and anteiso-C15 : 0, C16 : 0 and iso-C16 : 0 were the major fatty acids. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified aminophospholipids, four unidentified phospholipids and two unidentified lipids. meso-Diaminopimelic acid was detected in the peptidoglycan. The DNA G+C content was 55.4 mol%. Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain AMTAE16T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus hispanicus sp. nov. is proposed. The type strain is AMTAE16T(=LMG 29501T=CECT 9124T).

A novel actinobacterial strain, designated DS3010T, was isolated from a Black Sea marine sediment and characterized using a polyphasic approach. The strain was shown to have chemotaxonomic, morphological and phylogenetic properties consistent with classification as representing a member of the genus Micromonospora. Comparative 16S rRNA gene sequence studies showed that the strain was most closely related to the type strains of Micromonospora saelicesensis (99.5 %), Micromonospora chokoriensis (99.4 %) and Micromonospora violae (99.3 %). Similarly, a corresponding analysis based on partial gyrB gene sequences showed that it formed a distinct phyletic branch in a subclade that included the type strains of Micromonosporazamorensis, 'Micromonospora zeae', 'Micromonospora jinlongensis', M. saelicesensis and Micromonospora lupini. DS3010T was distinguished from its closest phylogenetic neighbours by low levels of DNA-DNA relatedness and by a combination of chemotaxonomic and phenotypic properties. On the basis of these data, it is proposed that the isolate should be assigned to the genus Micromonospora as Micromonospora profundi sp. nov. with isolate DS3010T (=DSM 45981T=KCTC 29243T) as the type strain.

A diversity study on the presence of strains representing the genus Micromonospora in Pisum sativum nodules collected from Cañizal (Spain) has provided evidence of the high number of isolates that might represent novel species. In the present work, we have characterized three of these isolates: GUI23T, GUI43T and GUI63T. Phenotypic and genotypic analyses confirmed that all strains represent novel species of the genus Micromonospora with the following proposed names: Micromonospora ureilytica sp. nov., type strain GUI23T (=CECT 9022T=DSM 101692T), Micromonospora noduli sp. nov., type strain GUI43T (=CECT 9020T=DSM 101694T), and Micromonospora vinacea sp. nov., type strain GUI63T (=CECT 9019T=DSM 101695T).

A Micromonospora strain, designated DS3186(T), isolated from sediment collected from the Black Sea off the Yason Peninsula, Ordu, Turkey, was examinated using a polyphasic approach. The strain was found to have chemotaxonomic, morphological and phylogenetic properties consistent with its clasification in the genus Micromonospora. A comparative 16S rRNA gene sequence analysis showed that the strain was closely related to the type strains of Micromonospora olivasterospora (99.0 %), Micromonospora equina (98.8 %), Micromonospora rhizosphaerae (98.8 %) and Micromonospora viridifaciens (98.8 %); low levels of DNA-DNA relatednes were found between the isolate and the M. olivasterospora and M. rhizosphaerae strains. Corresponding phylogenetic analysis based on partial gyrB gene sequences showed that strain DS3186(T) formed a subclade with the type strains of Micromonospora eburnea, M. equina, Micromonospora narathiwatensis and M. viridifaciens. Strain DS3186(T) was distinguished from its close phylogenetic neighbours using a combination of chemotaxonomic, morphological and physiological properties. Consequently, it is proposed that strain DS3186(T) represents a novel Micromonospora species for which the name Micromonospora yasonensis sp. nov. is proposed. The type strain is DS3186(T) (=DSM 45980(T) = KCTC 29433(T)).

Alnus glutinosa has been shown previously to synthesize, in response to nodulation by Frankia sp. ACN14a, an array of peptides called Alnus symbiotic up-regulated peptides (ASUPs). In a previous study one peptide (Ag5) was shown to bind to Frankia nitrogen-fixing vesicles and to modify their porosity. Here we analyse four other ASUPs, alongside Ag5, to determine whether they have different physiological effects on in vitro grown Frankia sp. ACN14a. The five studied peptides were shown to have different effects on nitrogen fixation, respiration, growth, the release of ions and amino acids, as well as on cell clumping and cell lysis. The mRNA abundance for all five peptides was quantified in symbiotic nodules and one (Ag11) was found to be more abundant in the meristem part of the nodule. These findings point to some peptides having complementary effects on Frankia cells.

Three novel actinobacterial strains, GUI2(T), GUI42 and CR21 isolated from nodular tissues and the rhizosphere of a sweet pea plant collected in Cañizal, Spain were identified according to their 16S rRNA gene sequences as new members of the genus Micromonospora. The closest phylogenetic members were found to be Micromonospora saelicesensis (99.2%) "Micromonospora zeae" (99.1%), "Micromonospora jinlongensis" (99%), Micromonospora lupini (98.9%) and Micromonospora zamorensis (98.8%). To resolve their full taxonomic position, four additional genes (atpD, gyrB, recA, rpoB) were partially sequenced and compared to available Micromonospora type strain sequences. DNA-DNA hybridization, BOX-PCR and ARDRA profiles confirmed that these strains represent a novel genomic species. All strains contained meso-diaminopimelic and hydroxy-diaminopimelic acids in their cell wall. Their fatty acid profiles comprised iso-C15:0, iso-C16:0 and anteiso-C15:0 as major components. The polar lipids diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol were found in the type strain GUI2(T) which also contained MK-10(H4) as the major menaquinone. Physiological and biochemical characteristics also differentiated the new isolates. Based on the integration of the above studies, strains GUI2(T), GUI42 and CR21 represent a novel Micromonospora species and we propose the name Micromonospora luteifusca sp. nov. The type strain is GUI2(T) (=CECT 8846(T); =DSM 100204(T))., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

In the present work we analyzed the taxonomic status of several Rhizobium strains isolated from Trifolium alexandrinum L. nodules in Egypt. The 16S rRNA genes of these strains were identical to those of Rhizobium bangladeshense BLR175(T) and Rhizobium binae BLR195(T). However, the analyses of recA and atpD genes split the strains into two clusters. Cluster II strains are identified as R. bangladeshense with >98% similarity values in both genes. The cluster I strains are phylogenetically related to Rhizobium etli CFN42(T) and R. bangladeshense BLR175(T), but with less than 94% similarity values in recA and atpD genes. DNA-DNA hybridization analysis showed 42% and 48% average relatedness between the strain 1010(T) from cluster I with respect to R. bangladeshense BLR175(T) and R. etli CFN42(T), respectively. Phenotypic characteristics of cluster I strains also differed from those of their closest related Rhizobium species. Analysis of the nodC gene showed that the strains belong to two groups within the symbiovar trifolii which was identified in Egypt linked to the species R. bangladeshense. Based on the genotypic and phenotypic characteristics, the group I strains belong to a new species for which the name Rhizobium aegyptiacum sp. nov. (sv. trifolii) is proposed, with strain 1010(T) being designated as the type strain (= USDA 7124(T)=LMG 29296(T)=CECT 9098(T))., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

A bacterial strain designated PM10T was isolated from root nodules of Periandra mediterranea in Brazil. Phylogenetic analyses based on 16S rRNA gene sequences placed the isolate in the genus Paenibacillus with its closest relatives being Paenibacillus vulneris CCUG 53270T and Paenibacillus yunnanensis YN2T with 95.6 and 95.9% 16S rRNA gene sequence similarity, respectively. The isolate was a Gram-stain-variable, motile, sporulating rod that was catalase-negative and oxidase-positive. Caseinase was positive, amylase was weakly positive and gelatinase was negative. Growth was supported by many carbohydrates and organic acids as carbon sources. MK-7 was the only menaquinone detected and anteiso-C15 : 0 was the major fatty acid. Major polar lipids were diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol and two unidentified lipids. meso-Diaminopimelic acid was detected in the peptidoglycan. The DNA G+C content was 52.9 mol%. Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain PM10T should be considered representative of a novel species of the genus Paenibacillus, for which the name Paenibacillus periandrae sp. nov. is proposed. The type strain is PM10T (=LMG 28691T=CECT 8827T).

For a long time, it was believed that a healthy plant did not harbor any microorganisms within its tissues, as these were often considered detrimental for the plant. In the last three decades, the numbers of studies on plant microbe-interactions has led to a change in our view and we now know that many of these invisible partners are essential for the overall welfare of the plant. The application of Next Generation Sequencing techniques is a powerful tool that has permitted the detection and identification of microbial communities in healthy plants. Among the new plant microbe interactions recently reported several actinobacteria such as Micromonospora are included. Micromonospora is a Gram-positive bacterium with a wide geographical distribution; it can be found in the soil, mangrove sediments, and freshwater and marine ecosistems. In the last years our group has focused on the isolation of Micromonospora strains from nitrogen fixing nodules of both leguminous and actinorhizal plants and reported for the first time its wide distribution in nitrogen fixing nodules of both types of plants. These studies have shown how this microoganism had been largely overlooked in this niche due to its slow growth. Surprisingly, the genetic diversity of Micromonospora strains isolated from nodules is very high and several new species have been described. The current data indicate that Micromonospora saelicesensis is the most frequently isolated species from the nodular tissues of both leguminous and actinorhizal plants. Further studies have also been carried out to confirm the presence of Micromonospora inside the nodule tissues, mainly by specific in situ hybridization. The information derived from the genome of the model strain, Micromonospora lupini, Lupac 08, has provided useful information as to how this bacterium may relate with its host plant. Several strategies potentially necessary for Micromonospora to thrive in the soil, a highly competitive, and rough environment, and as an endophytic bacterium with the capacity to colonize the internal plant tissues which are protected from the invasion of other soil microbes were identified. The genome data also revealed the potential of M. lupini Lupac 08 as a plant growth promoting bacterium. Several loci involved in plant growth promotion features such as the production of siderophores, phytohormones, and the degradation of chitin (biocontrol) were also located on the genome and the functionality of these genes was confirmed in the laboratory. In addition, when several host plants species were inoculated with Micromonospora strains, the plant growth enhancing effect was evident under greenhouse conditions. Unexpectedly, a high number of plant-cell wall degrading enzymes were also detected, a trait usually found only in pathogenic bacteria. Thus, Micromonospora can be added to the list of new plant-microbe interactions. The current data indicate that this microorganism may have an important application in agriculture and other biotechnological processes. The available information is promising but limited, much research is still needed to determine which is the ecological function of Micromonospora in interaction with nitrogen fixing plants.

Nonfilamentous actinobacteria have been less studied as secondary metabolite producers than their filamentous counterparts such as Streptomyces. From our collection of nonfilamentous actinobacteria isolated from sandstone, an Arthrobacter strain was found to produce a new cyclic peptide arthroamide (1) together with the known compound turnagainolide A (2). These compounds inhibited the quorum sensing signaling of Staphylococcus aureus in the submicromolar to micromolar range.

Actinorhizal plant growth in pioneer ecosystems depends on the symbiosis with the nitrogen-fixing actinobacterium Frankia cells that are housed in special root organs called nodules. Nitrogen fixation occurs in differentiated Frankia cells known as vesicles. Vesicles lack a pathway for assimilating ammonia beyond the glutamine stage and are supposed to transfer reduced nitrogen to the plant host cells. However, a mechanism for the transfer of nitrogen-fixation products to the plant cells remains elusive. Here, new elements for this metabolic exchange are described. We show that Alnus glutinosa nodules express defensin-like peptides, and one of these, Ag5, was found to target Frankia vesicles. In vitro and in vivo analyses showed that Ag5 induces drastic physiological changes in Frankia, including an increased permeability of vesicle membranes. A significant release of nitrogen-containing metabolites, mainly glutamine and glutamate, was found in N2-fixing cultures treated with Ag5. This work demonstrates that the Ag5 peptide is central for Frankia physiology in nodules and uncovers a novel cellular function for this large and widespread defensin peptide family.

Cicer canariense is a threatened endemic legume from the Canary Islands where it can be nodulated by mesorhizobial strains from the symbiovar ciceri, which is the common worldwide endosymbiont of Cicer arietinum linked to the genus Mesorhizobium. However, when C. canariense was cultivated in a soil from mainland Spain, where the symbiovar ciceri is present, only fast-growing rhizobial strains were unexpectedly isolated from its nodules. These strains were classified into the genus Rhizobium by analysis of the recA and atpD genes, and they were phylogenetically related to Rhizobium leguminosarum. The analysis of the nodC gene showed that the isolated strains belonged to the symbiovar trifolii that harbored a nodC allele (β allele) different to that harbored by other strains from this symbiovar. Nodulation experiments carried out with the lacZ-labeled strain RCCHU01, representative of the β nodC allele, showed that it induced curling of root hairs, infected them through infection threads, and formed typical indeterminate nodules where nitrogen fixation took place. This represents a case of exceptional performance between the symbiovar trifolii and a legume from the tribe Cicereae that opens up new possibilities and provides new insights into the study of rhizobia-legume symbiosis., (Copyright © 2015 Elsevier GmbH. All rights reserved.)

Background: Trees belonging to the Casuarinaceae and Betulaceae families play an important ecological role and are useful tools in forestry for degraded land rehabilitation and reforestation. These functions are linked to their capacity to establish symbiotic relationships with a nitrogen-fixing soil bacterium of the genus Frankia. However, the molecular mechanisms controlling the establishment of these symbioses are poorly understood. The aim of this work was to identify potential transcription factors involved in the establishment and functioning of actinorhizal symbioses., Results: We identified 202 putative transcription factors by in silico analysis in 40 families in Casuarina glauca (Casuarinaceae) and 195 in 35 families in Alnus glutinosa (Betulaceae) EST databases. Based on published transcriptome datasets and quantitative PCR analysis, we found that 39% and 26% of these transcription factors were regulated during C. glauca and A. glutinosa-Frankia interactions, respectively. Phylogenetic studies confirmed the presence of common key transcription factors such as NSP, NF-YA and ERN-related proteins involved in nodule formation in legumes, which confirm the existence of a common symbiosis signaling pathway in nitrogen-fixing root nodule symbioses. We also identified an actinorhizal-specific transcription factor belonging to the zinc finger C1-2i subfamily we named CgZF1 in C. glauca and AgZF1 in A. glutinosa., Conclusions: We identified putative nodulation-associated transcription factors with particular emphasis on members of the GRAS, NF-YA, ERF and C2H2 families. Interestingly, comparison of the non-legume and legume TF with signaling elements from actinorhizal species revealed a new subgroup of nodule-specific C2H2 TF that could be specifically involved in actinorhizal symbioses. In silico identification, transcript analysis, and phylogeny reconstruction of transcription factor families paves the way for the study of specific molecular regulation of symbiosis in response to Frankia infection.

A bacterial strain designated RLAHU15(T) was isolated from root nodules of Lupinus albus in Spain. Phylogenetic analyses based on 16S rRNA gene sequences placed the isolate in the genus Paenibacillus, with its closest relatives being Paenibacillus catalpae D75(T), Paenibacillus glycanilyticus DS-1(T), Paenibacillus endophyticus PECAE04(T) and Paenibacillus xinjiangensis B538(T) with 98.8 %, 98.9 %, 97.4 % and 97.4 % similarity, respectively. DNA-DNA hybridization studies showed values lower than 45 % between the strain RLAHU15(T) and any of these species. The isolate was a Gram-stain positive, motile and sporulating rod. Catalase activity was weak and oxidase activity was positive. Casein and starch were hydrolysed but gelatin was not. Growth was supported by many carbohydrates and organic acids as carbon sources. MK-7 was the only menaquinone detected and anteiso-C15 : 0 and iso-C16 : 0 were the major fatty acids. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, three unidentified phospholipids and an unidentified lipid. meso-Diaminopimelic acid was detected in the peptidoglycan. The DNA G+C content was 54.4 mol%. Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain RLAHU15(T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus lupini sp. nov. is proposed. The type strain is RLAHU15(T) ( = LMG 27296(T) = CECT 8235(T))., (© 2014 IUMS.)