Guidelines for the description of rhizobial symbiovars

Rhizobia are bacteria that form nitrogen-fixing nodules in legume plants. The sets of genes responsible for both nodulation and nitrogen fixation are carried in plasmids or genomic islands that are often mobile. Different strains within a species sometimes have different host specificities, while very similar symbiosis genes may be found in strains of different species. These specificity variants are known as symbiovars, and many of them have been given names, but there are no established guidelines for defining or naming them. Here, we discuss the requirements for guidelines to describe symbiovars, propose a set of guidelines, provide a list of all symbiovars for which descriptions have been published so far, and offer a mechanism to maintain a list in the future.

Agrobacterium cavarae sp. nov., isolated from maize (Zea mays L.) roots

A bacterial strain designated as RZME10^T was isolated from a Zea mays L. root collected in Spain. Results of analysis of the 16S rRNA gene sequence showed that this strain belongs to the genus Agrobacterium with Agrobacterium larrymoorei ATCC 51759^T being the most closely related species with 99.9 % sequence similarity. The similarity values of the rpoB, recA, gyrB, atpD and glnII genes between strain RZME10^T and A. larrymoorei ATCC 51759^T were 93.5, 90.0, 88.7, 87.9 and 90.1 %, respectively. The estimated average nucleotide identity using blast and digital DNA-DNA hybridization values between these two strains were 80.4 and 30.2 %, respectively. The major fatty acids of strain RZME10^T are those from summed feature 8 (C_18 : 1 ω6c/C_18 : 1 ω7c) and C_16 : 0. Pathogenicity tests on tomato and carrot roots showed that strain RZME10^T was not able to induce plant tumours. Based on the results of genomic, chemotaxonomic and phenotypic analyses, we propose that strain RZME10^T represents a novel species named Agrobacterium cavarae sp. nov. (type strain RZME10^T=CECT 9795^T=LMG 31257^T).

Effect of cardiac resynchronization therapy on septal perfusion and septal thickening: Association with left ventricular function, reverse remodelling and dyssynchrony

BACKGROUND

We evaluated the effect of cardiac resynchronization therapy (CRT) on septal perfusion and thickening at 6 months post implantation assessed on Tc99m-MIBI Gated myocardial perfusion SPECT (GMPS).We also studied the association of change in septal perfusion and thickening with primary outcome defined as at least one [improvement in ≥1NYHA class, left ventricular ejection fraction (LVEF) by ≥ 5%, reduction of end-systolic volume (ESV) by ≥ 15%, and improvement ≥ 5 points in Minnesota living with heart failure questionnaire (MLHFQ)].

METHOD

One hundred and five patients underwent clinical and GMPS evaluation before and at 6 months post CRT.

RESULT

Post CRT there was significant improvement in mean normalized septal perfusion uptake and in septal thickening (P value = 0.001, both). There was no significant relation between improvement in septal perfusion and primary outcome. However, improvement in septal thickening was statistically significant with favorable primary outcome (P = 0.001).There was no significant correlation between improvement of septal perfusion and improvement in LVEF, reduction in End diastolic volume (EDV), ESV, and Left ventricular Dyssynchrony (LVD). But, there was significant correlation between improvement of septal thickening and these parameters.

CONCLUSION

Improvement in septal thickening was associated with reverse remodeling, improvement in LVEF, and reduction of LVD.

Impact of International Atomic Energy Agency support to the development of nuclear cardiology in low-and-middle-income countries: Case of Latin America and the Caribbean

Cardiovascular diseases (CVDs) are the leading cause of death in Latin America and the Caribbean (LAC) region as well as worldwide. Lifestyle, nutritional habits and the upsurge of obesity have contributed to the increase in the prevalence of CVDs in the region. The role of nuclear cardiology in the management of patients with CVDs is well established. Particularly, myocardial perfusion imaging is widely used in LAC countries and has been increasingly integrated into the healthcare systems in the region for the diagnosis of coronary artery disease, risk stratification and to guide patient management. In its role to support countries around the world to address their health needs through the peaceful applications of nuclear techniques, the International Atomic Energy Agency (IAEA) has provided assistance to the LAC region for the establishment and strengthening of the nuclear cardiology practice. To that extent, the IAEA provides support in building capacities of multidisciplinary teams of professionals, the provision of medical equipment and the promotion of communication and exchange of knowledge among the different stakeholders. In addition, the IAEA encourages the participation of nuclear medicine centers in international multi-center research studies. In this paper, we present some of the projects through which the IAEA has supported the LAC region, including regional technical cooperation projects and coordinated research projects related to cardiology within the current multimodality approach to cardiac imaging.

Minimal standards for the description of new genera and species of rhizobia and agrobacteria

Herein the members of the Subcommittee on Taxonomy of Rhizobia and Agrobacteria of the International Committee on Systematics of Prokaryotes review recent developments in rhizobial and agrobacterial taxonomy and propose updated minimal standards for the description of new species (and genera) in these groups. The essential requirements (minimal standards) for description of a new species are (1) a genome sequence of at least the proposed type strain and (2) evidence for differentiation from other species based on genome sequence comparisons. It is also recommended that (3) genetic variation within the species is documented with sequence data from several clearly different strains and (4) phenotypic features are described, and their variation documented with data from a relevant set of representative strains. Furthermore, it is encouraged that information is provided on (5) nodulation or pathogenicity phenotypes, as appropriate, with relevant gene sequences. These guidelines supplement the current rules of general bacterial taxonomy, which require (6) a name that conforms to the International Code of Nomenclature of Prokaryotes, (7) validation of the name by publication either directly in the International Journal of Systematic and Evolutionary Microbiology or in a validation list when published elsewhere, and (8) deposition of the type strain in two international culture collections in separate countries.

Appropriate use of noninvasive ischemia testing to guide revascularization decision making following acute ST elevation myocardial infarction in Latin American countries: Results from an expert panel meeting of the International Atomic Energy Agency

Across Latin American and Caribbean countries, cardiovascular disease and especially ischemic heart disease is currently the main cause of death both in men and in women. For most Latin American and Caribbean countries, public and community health efforts aim to define care strategies which are both clinically and cost effective and promote primary and secondary prevention, resulting in improved patient outcomes. The optimal approach to deal with acute events such as ST-elevation myocardial infarction (STEMI) is a matter of controversy; however, there is an expanding role for assessing residual ischemic burden in STEMI patients following primary percutaneous coronary intervention. Although randomized clinical trials have established the value of staged fractional flow reserve-guided revascularization, the use of noninvasive functional imaging modalities may play a similar role at a much lower cost. For LAC, available stress imaging techniques could be applied to define residual ischemia in the non-infarct related artery and to target revascularization in a staged procedure after primary percutaneous coronary intervention The use of nuclear cardiac imaging, supported by its relatively wide availability, moderate cost, and robust quantitative capabilities, may serve to guide effective care and to reduce subsequent cardiac events in patients with coronary artery disease. This noninvasive approach may avert potential safety issues with repeat and lengthy invasive procedures, and serve as a baseline for subsequent follow-up stress testing following the index STEMI event. This consensus document was devised from an expert panel meeting of the International Atomic Energy Agency, highlighting available evidence with a focus on the utility of stress myocardial perfusion imaging in post-STEMI patients. The document could serve as guidance to the prudent and appropriate use of nuclear imaging for targeting therapeutic management and avoiding unnecessary invasive procedures within Latin American and Caribbean countries, where resources could be scarce.

Bradyrhizobium cajani sp. nov. isolated from nodules of Cajanus cajan

Two slow-growing strains, AMBPC1010T and AMBPC1011, were isolated from nodules of Cajanus cajan in the Dominican Republic. 16S rRNA gene analysis placed these strains within the genus Bradyrhizobium, being phylogenetically equidistant to several species of this genus. Analysis of the recA and atpD genes showed that the strains isolated belong to a cluster containing the strains Bradyrhizobium ottawaense OO99T, 'Bradyrhizobium americanum' CMVU44 and Bradyrhizobium daqingense CCBAU 15774T, and presented similarity values lower than 96 % for both genes with respect to the strains nodulating C. cajan. DNA-DNA hybridization analysis showed averages of 36, 40 and 39 % relatedness with respect to the representative strains of Bradyrhizobium ottawaense, 'Bradyrhizobium americanum' and Bradyrhizobium daqingense, respectively. Phenotypic characteristics also differed from those of the most closely related species of the genus Bradyrhizobium. Therefore, based on the data obtained in this study, we propose to classify the strains AMBPC1010T (=LMG 29967T=CECT 9227T) and AMBPC1011 into a novel species named Bradyrhizobium cajani sp. nov.

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).

Legume bioactive compounds: influence of rhizobial inoculation

Legumes consumption has been recognized as beneficial for human health, due to their content in proteins, fiber, minerals and vitamins, and their cultivation as beneficial for sustainable agriculture due to their ability to fix atmospheric nitrogen in symbiosis with soil bacteria known as rhizobia. The inoculation with these baceria induces metabolic changes in the plant, from which the more studied to date are the increases in the nitrogen and protein contents, and has been exploited in agriculture to improve the crop yield of several legumes. Nevertheless, legumes also contain several bioactive compounds such as polysaccharides, bioactive peptides, isoflavones and other phenolic compounds, carotenoids, tocopherols and fatty acids, which makes them functional foods included into the nutraceutical products. Therefore, the study of the effect of the rhizobial inoculation in the legume bioactive compounds content is gaining interest in the last decade. Several works reported that the inoculation of different genera and species of rhizobia in several grain legumes, such as soybean, cowpea, chickpea, faba bean or peanut, produced increases in the antioxidant potential and in the content of some bioactive compounds, such as phenolics, flavonoids, organic acids, proteins and fatty acids. Therefore, the rhizobial inoculation is a good tool to enhance the yield and quality of legumes and further studies on this field will allow us to have plant probiotic bacteria that promote the plant growth of legumes improving their functionality.

Invasion of the Brazilian campo rupestre by the exotic grass Melinis minutiflora is driven by the high soil N availability and changes in the N cycle

The Serra do Rola Moça State Park (PESRM) in Minas Gerais State, Brazil is a preserved site representative of the campo rupestre biome over an ironstone outcrop that has a high level of plant diversity. Almost 60% of this grassy field has been invaded by the exotic molasses grass (Melinis minutiflora), which constitutes a severe threat to the biodiversity and survival of this biome, particularly due to the impacts of annual fires and inappropriate restoration interventions. Many invasive species exhibit a high demand for nitrogen (N). Hence, this work aimed to study the N cycle alterations promoted by M. minutiflora in a site of the campo rupestre, where the leguminous species Mimosa pogocephala was prevalent. The biome's soils exhibited a high natural N fertility and low C:N ratio. The main N source in this biome resulted from the biological N fixation performed by M. pogocephala associated with Burkholderia nodosa, as evidenced by the total leaf N content, leaf δ¹⁵N signature, nodule occupation and bacterial molecular identification analyses. The displacement of native species by molasses grass was associated with changes in the soil N forms, namely the nitrate increased as the ammonium decreased. The latter was the dominant N form in the native species plots, as observed in the soil analysis of total N, ammonium and nitrate contents. The dominant ammonium form was changed to the nitric form by the stimulation of ammonia-oxidising bacteria populations due to the invasive species. Therefore, the key mechanism behind the invasiveness of the exotic grass and the concomitant displacement of the native species may be associated with changes in the soil N chemical species. Based on this finding and on the high N-based soil fertility found in the campo rupestre N fertilisation procedures for restoration of invaded areas should be strictly avoided in this biome.

Reclassification of strains MAFF 303099T and R7A into Mesorhizobiumjaponicum sp. nov

In this work we revise the taxonomic status of the Lotus-nodulating strains MAFF 303099T and R7A isolated in Japan and New Zealand, respectively. Their 16S rRNA gene sequences are identical and show 98.0, 99.7, 99.8 and 99.9 % similarity values with respect to Mesorhizobium loti NZP 2213T, M. jarvisii ATCC 33669T, M. huakuii USDA 4779T (=CCBAU 2609T) and M. erdmanii USDA 3471T, respectively. The analysis of recA and glnII gene sequeces showed that M. jarvisii ATCC 33669T and M. huakuii USDA 4779T (=CCBAU 2609T) are the most closely related strains to MAFF 303099T and R7A, with similarity values suggesting that these two strains belong to a different species for which MAFF 303099T is selected as the type strain. The DNA-DNA relatedness values between strain MAFF 303099T and its closest phylogenetic relatives ranged from 53 to 60 % in average. Strains MAFF 303099T and R7A presented slight differences in the proportions of C18 : 1ω7c 11-methyl and C19 : 0 cyclo ω8c fatty acids with respect to M. jarvisii ATCC 33669T and M. huakuii USDA 4779T, and also in several phenotypic characteristics. Therefore, we propose the reclassification of these two strains into a novel species named Mesorhizobium japonicum sp. nov., with the type strain being MAFF 303099T (=LMG 29417T=CECT 9101T).

Paenibacillus periandrae sp. nov., isolated from nodules of Periandra mediterranea

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).

Pseudomonas coleopterorum sp. nov., a cellulase-producing bacterium isolated from the bark beetle Hylesinus fraxini

We isolated a strain coded Esc2Am(T) during a study focused on the microbial diversity of adult specimens of the bark beetle Hylesinus fraxini. Its 16S rRNA gene sequence had 99.4% similarity with respect to its closest relative, Pseudomonas rhizosphaerae IH5(T). The analysis of partial sequences of the housekeeping genes rpoB, rpoD and gyrB confirmed that strain Esc2Am(T) formed a cluster with P. rhizosphaerae IH5(T) clearly separated from the remaining species of the genus Pseudomonas. Strain Esc2Am(T) had polar flagella and could grow at temperatures from 4 °C to 30 °C. The respiratory quinone was Q9 and the main fatty acids were C16 : 0, C18 : 1ω7c and/or C18 : 1ω6c in summed feature 8 and C16 : 1ω7c and/or C16 : 1ω6c in summed feature 3. DNA-DNA hybridization results showed 51% relatedness with respect to P. rhizosphaerae IH5(T). Oxidase, catalase and urease-positive, the arginine dihydrolase system was present but nitrate reduction and β-galactosidase production were negative. Aesculin hydrolysis was positive. Based on the results from the genotypic, phenotypic and chemotaxonomic analyses, we propose the classification of strain Esc2Am(T) as representing a novel species of the genus Pseudomonas, for which we propose the name Pseudomonas coleopterorum sp. nov. The type strain is Esc2Am(T) ( = LMG 28558(T)= CECT 8695(T)).

Revision of the taxonomic status of the species Rhizobium lupini and reclassification as Bradyrhizobium lupini comb. nov

The species Rhizobium lupini was isolated from Lupinus nodules and included in the Approved Lists of Bacterial Names in 1980. Nevertheless, on the basis of the analysis of the type strain of this species available in DSMZ, DSM 30140T, whose 16S rRNA gene was identical to that of the type strain of Bradyrhizobium japonicum , R. lupini was considered a later synonym of this species. In this study we confirmed that the strain DSM 30140T belongs to the species B. japonicum , but also that it cannot be the original strain of R. lupini because this species effectively nodulated Lupinus whereas strain DSM 30140T was able to nodulate soybean but not Lupinus. Since the original type strain of R. lupini was deposited into the USDA collection by L. W. Erdman under the accession number USDA 3051T we analysed the taxonomic status of this strain showing that although it belongs to the genus Bradyrhizobium instead of genus Rhizobium , it is phylogenetically distant from B. japonicum and closely related to Bradyrhizobium canariense . The type strains R. lupini USDA 3051T and B. canariense BTA-1T share 16S rRNA, recA and glnII gene sequences with similarities of 99.8 %, 96.5 % and 97.1 %, respectively. They presented a DNA–DNA hybridization value of 36 % and also differed in phenotypic characteristics and slightly in the proportions of some fatty acids. Therefore we propose the reclassification of the species Rhizobium lupini as Bradyrhizobium lupini comb. nov. The type strain is USDA 3051T ( = CECT 8630T = LMG 28514T).

Fontibacillus solani sp. nov. isolated from potato (Solanum tuberosum L.) root

A bacterial strain designated A4STR04(T) was isolated from the inner root tissue of potatoes in Spain. Phylogenetic analysis based on the 16S rRNA gene sequence placed the isolate into the genus Fontibacillus, being most closely related to Fontibacillus panacisegetis KCTC 13564(T) with 99% identity. The isolate was observed to form Gram-positive, motile and sporulating rods. The catalase test was found to be negative and oxidase positive. Nitrate was found to be reduced to nitrite. β-Galactosidase and caseinase were observed to be produced but the production of gelatinase, urease, arginine dehydrolase, ornithine and lysine decarboxylase was negative. Aesculin hydrolysis was found to be positive and acetoin production was negative. Growth was found to be supported by many carbohydrates and organic acids as carbon source. MK-7 was the only menaquinone detected and the major fatty acid (61.5%) was identified as anteiso-C(15:0), as occurs in the other species of genus Fontibacillus. The strain A4STR04(T) was found to display a complex lipid profile consisting of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, a glycolipid, two phospholipids, a lipid and two aminophospholipids. Mesodiaminopimelic acid was detected in the peptidoglycan. The G+C content was determined to be 50.5 mol% (Tm). Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain A4STR04(T) (=LMG 28458 (T) = CECT 8693(T)) should be classified as representing a novel species of genus Fontibacillus, for which the name Fontibacillus solani sp. nov. is proposed.

Paenibacillus lupini sp. nov., isolated from nodules of Lupinus albus

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)).

Inoculation of the nonlegume Capsicum annuum L. with Rhizobium strains. 2. Changes in sterols, triterpenes, fatty acids, and volatile compounds

Peppers (Capsicum spp.) are consumed worldwide, imparting flavor, aroma, and color to foods, additionally containing high concentrations of biofunctional compounds. This is the first report about the effect of the inoculation of two Rhizobium strains on sterols, triterpenes, fatty acids, and volatile compounds of leaves and fruits of pepper (Capsicum annuum L.) plants. Generally, inoculation with strain TVP08 led to the major changes, being observed a decrease of sterols and triterpenes and an increase of fatty acids, which are related to higher biomass, growth, and ripening of pepper fruits. The increase of volatile compounds may reflect the elicitation of plant defense after inoculation, since the content on methyl salicylate was significantly increased in inoculated material. The findings suggest that inoculation with Rhizobium strains may be employed to manipulate the content of interesting metabolites in pepper leaves and fruits, increasing potential health benefits and defense abilities of inoculated plants.

Inoculation of the nonlegume Capsicum annuum (L.) with Rhizobium strains. 1. Effect on bioactive compounds, antioxidant activity, and fruit ripeness

Pepper (Capsicum annuum L.) is an economically important agricultural crop and an excellent dietary source of natural colors and antioxidant compounds. The levels of these compounds can vary according to agricultural practices, like inoculation with plant growth-promoting rhizobacteria. In this work we evaluated for the first time the effect of the inoculation of two Rhizobium strains on C. annuum metabolites and bioactivity. The results revealed a decrease of organic acids and no effect on phenolics and capsaicinoids of leaves from inoculated plants. In the fruits from inoculated plants organic acids and phenolic compounds decreased, showing that fruits from inoculated plants present a higher ripeness stage than those from uninoculated ones. In general, the inoculation with Rhizobium did not improve the antioxidant activity of pepper fruits and leaves. Considering the positive effect on fruit ripening, the inoculation of C. annuum with Rhizobium is a beneficious agricultural practice for this nonlegume.

Rhizobium laguerreae sp. nov. nodulates Vicia faba on several continents

Several fast-growing strains nodulating Vicia faba in Peru, Spain and Tunisia formed a cluster related to Rhizobium leguminosarum . The 16S rRNA gene sequences were identical to that of R. leguminosarum USDA 2370T, whereas rpoB, recA and atpD gene sequences were phylogenetically distant, with sequence similarities of less than 96 %, 97 % and 94 %, respectively. DNA–DNA hybridization analysis showed a mean relatedness value of 43 % between strain FB206T and R. leguminosarum USDA 2370T. Phenotypic characteristics of the novel strains also differed from those of the closest related species of the genus Rhizobium . Therefore, based on genotypic and phenotypic data obtained in this study, we propose to classify this group of strains nodulating Vicia faba as a novel species of the genus Rhizobium named Rhizobium laguerreae sp. nov. The type strain is FB206T ( = LMG 27434T = CECT 8280T).

Cohnella lupini sp. nov., an endophytic bacterium isolated from root nodules of Lupinus albus

A bacterial strain designated RLAHU4BT was isolated from root nodules of Lupinus albus in León (Spain). The 16S rRNA gene sequence of this strain showed similarities lower than 97 % with respect to species of the genus Cohnella . The strain was a Gram-variable, sporulating rod, motile by means of peritrichous flagella, and facultatively anaerobic. It was positive for oxidase, catalase and β-galactosidase production but negative for urease, amylase and gelatinase. Strain RLAHU4BT grew in the presence of 5 % NaCl. MK-7 was the predominant menaquinone and meso-diaminopimelic acid was present in the peptidoglycan. anteiso-C15 : 0, iso-C16 : 0, iso-C15 : 0 and C16 : 0 were the major fatty acids. Major polar lipids of strain RLAHU4BT were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unknown phospholipids, two unknown aminophospholipids and one unknown lipid. The DNA G+C content was 57.8 mol%. Strain RLAHU4BT presented phenotypic differences from all recognized species of the genus Cohnella . The phylogenetic, chemotaxonomic and phenotypic data indicated that strain RLAHU4BT belongs to a novel species of the genus Cohnella , for which the name Cohnella lupini sp. nov. is proposed, with strain RLAHU4BT ( = LMG 27416T = CECT 8236T) as the type strain.

Phyllobacterium loti sp. nov. isolated from nodules of Lotus corniculatus

Strain S658(T) was isolated from a Lotus corniculatus nodule in a soil sample obtained in Uruguay. Phylogenetic analysis of the 16S rRNA gene and atpD gene showed that this strain clustered within the genus Phyllobacterium. The closest related species was, in both cases, Phyllobacterium trifolii PETP02(T) with 99.8 % sequence similarity in the 16S rRNA gene and 96.1 % in the atpD gene. The 16S rRNA gene contains an insert at the beginning of the sequence that has no similarities with other inserts present in the same gene in described rhizobial species. Ubiquinone Q-10 was the only quinone detected. Strain S658(T) differed from its closest relatives through its growth in diverse culture conditions and in the assimilation of several carbon sources. It was not able to reproduce nodules in Lotus corniculatus. The results of DNA-DNA hybridization, phenotypic tests and fatty acid analyses confirmed that this strain should be classified as a representative of a novel species of the genus Phyllobacterium, for which the name Phyllobacterium loti sp. nov. is proposed. The type strain is S658(T)( = LMG 27289(T) = CECT 8230(T)).

Physiological and antioxidant responses of Medicago sativa-rhizobia symbiosis to cyanobacterial toxins (Microcystins) exposure

Toxic cyanobacteria in freshwaters can induce potent harmful effects on growth and development of plants irrigated with contaminated water. In this study, the effect of cyanobacteria extract containing Microcystins (MC) on Medicago sativa-rhizobia symbiosis was investigated in order to explore plants response through biomass production, photosynthetic pigment and antioxidant enzymes analysis: Peroxidase (POD), Polyphenoloxidase (PPO) and Catalase (CAT). Alfalfa plants were inoculated with two endosymbiotic rhizobial strains: RhOL1 (MC less sensitive strain) and RhOL3 (MC more sensitive strain), to evaluate the rhizobial contribution on the plant response cultured under cyanobacterial toxins stress. The two rhizobia strains were identified as Ensifer meliloti by sequence analysis of their rrs and atpD genes. The chronic exposure to MC extract showed shoot, root and nodules dry weight decrease, in both symbiosis cultures. The rate of decline in plants inoculated with RhOL3 was higher than that in symbiosis with RhOL1 mainly at 20 μg L(-1) of MC. Cyanotoxins also reduced photosynthetic pigment content and generated an oxidative stress observed at cellular level. POD, PPO and CAT activities were significantly increased in leaves, roots and nodules of alfalfa plants exposed to MC. These enzyme activities were higher in plants inoculated with RhOL3 especially when alfalfa plants were exposed to 20 μg L(-1) of MC. The present paper reports new scientific finding related to the behavior of rhizobia-M. sativa associations to MC (Microcystins) for later recommendation concerning the possible use of these symbiosis face to crops exposure to MC contaminated water irrigation.

Paenibacillus endophyticus sp. nov., isolated from nodules of Cicer arietinum

A bacterial strain, designated PECAE04(T), was isolated from root nodules of Cicer arietinum in Spain. Phylogenetic analysis based on 16S rRNA gene sequence placed the isolate into the genus Paenibacillus with its closest relative being Paenibacillus castaneae Ch-32(T) with 98.4 % 16S rRNA gene sequence similarity followed by Paenibacillus glycanilyticus DS-1(T), Paenibacillus prosopidis PW21(T), Paenibacillus xinjiangensis B538(T) and Paenibacillus catalpae D75(T) with similarities ranging from 97.9 to 96.8 %. DNA-DNA hybridization measurements showed values lower than 20 % between the strain PECAE04(T) and any of these species. The isolate was a Gram-stain-positive, motile, sporulating rod. Catalase and oxidase activities were positive. Aesculin was hydrolysed but casein and gelatin were not. Acetoin production, H2S production, nitrate reduction and urease and caseinase production were negative. Growth was supported by many carbohydrates and organic acids as carbon sources. MK-7 was the predominant menaquinone and anteiso-C15 : 0, iso-C16 : 0 and C16 : 0 were the major fatty acids. Major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, a glycolipid, three phospholipids and an unidentified lipid. Meso-diaminopimelic acid was not detected in the peptidoglycan. The DNA G+C content was 52.9 mol%. Phylogenetic, chemotaxonomic and phenotypic analyses showed that strain PECAE04(T) should be considered to be a representative of a novel species of the genus Paenibacillus, for which the name Paenibacillus endophyticus sp. nov. is proposed. The type strain is PECAE04(T) ( = LMG 27297(T) = CECT 8234(T)).

Pseudomonas guariconensis sp. nov., isolated from rhizospheric soil

We isolated a bacterial strain designated PCAVU11(T) in the course of a study of phosphate-solubilizing bacteria occurring in rhizospheric soil of Vigna unguiculata (L.) Walp. in Guárico state, Venezuela. The 16S rRNA gene sequence had 99.2 % sequence similarity with respect to the most closely related species, Pseudomonas taiwanensis, and 99.1 % with respect to Pseudomonas entomophila, Pseudomonas plecoglossicida and Pseudomonas monteilii, on the basis of which PCAVU11(T) was classified as representing a member of the genus Pseudomonas. Analysis of the housekeeping genes rpoB, rpoD and gyrB confirmed the phylogenetic affiliation and showed sequence similarities lower than 95 % in all cases with respect to the above-mentioned closest relatives. Strain PCAVU11(T) showed two polar flagella. The respiratory quinone was Q9. The major fatty acids were 16 : 0 (25.7 %), 18 : 1ω7c (20.4 %), 17 : 0 cyclo (11.5 %) and 16 : 1ω7c/15 : 0 iso 2-OH in summed feature 3 (10.8 %). The strain was oxidase-, catalase- and urease-positive, the arginine dihydrolase system was present but nitrate reduction, β-galactosidase production and aesculin hydrolysis were negative. Strain PCAVU11(T) grew at 44 °C and at pH 10. The DNA G+C content was 61.5 mol%. DNA-DNA hybridization results showed values lower than 56 % relatedness with respect to the type strains of the four most closely related species. Therefore, the results of genotypic, phenotypic and chemotaxonomic analyses support the classification of strain PCAVU11(T) as representing a novel species of the genus Pseudomonas, which we propose to name Pseudomonas guariconensis sp. nov. The type strain is PCAVU11(T) ( = LMG 27394(T) = CECT 8262(T)).

Centrosema is a promiscuous legume nodulated by several new putative species and symbiovars of Bradyrhizobium in various American countries

Centrosema is an American indigenous legume that can be used in agroecosystems for recovery of acidic and degraded soils. In this study, a Centrosema-nodulating rhizobial collection of strains isolated in a poor acid savanna soil from Venezuela was characterized, and the members of the collection were compared to other Centrosema strains from America. The analysis of the rrs gene showed that the strains nodulating Centrosema in American countries were closely related to different species of the genus Bradyrhizobium. However, the analysis of the atpD and recA genes, as well as the 16S-23S ITS region, showed that they formed several new phylogenetic lineages within this genus. The Venezuela strains formed three lineages that were divergent among themselves and with respect to those formed by Centrosema strains isolated in other countries, as well as to the currently described species and genospecies of Bradyrhizobium. In addition, the symbiotic genes nodC and nifH carried by Centrosema-nodulating strains were analyzed for the first time, and it was shown that they belonged to three new phylogenetic lineages within Bradyrhizobium. The nodC genes of the Centrosema strains were divergent among themselves and with respect to the genistearum and glycinearum symbiovars, indicating that Centrosema is a promiscuous legume. According to these results, the currently known Centrosema-nodulating strains represent several new putative species and symbiovars of the genus Bradyrhizobium.

Pseudomonas punonensis sp. nov., isolated from straw

During a study of the ‘tunta’ (frozen-dry potato) production process in Peru, a bacterial strain, LMT03T, was isolated from the straw grass in which the potatoes are dried. This strain was classified into the genus Pseudomonas on the basis of the 16S rRNA gene sequence analysis, and is most closely related to Pseudomonas argentinensis CH01T with 99.3 % identity in this gene and 96 %, 92 % and 86 % identities in rpoB, rpoD and gyrB genes, respectively. Strain LMT03T has a single polar flagellum, like other related yellow-pigment-producing pseudomonads. The major quinone is Q-9. The major fatty acids are C18 : 1ω7c in summed feature 8 (40.82 %), C16 : 1ω6c/C16 : 1ω6c in summed feature 3 (23.72 %) and C16 : 0 (15.20 %). The strain produces oxidase but it does not produce gelatinase, indole, urease, arginine dihydrolase or β-galactosidase. Catalase production was very weak after 28 and 48 h incubation on nutrient agar medium. Nitrate reduction is negative. It does not hydrolyse aesculin. The DNA G+C content is 57.8 mol%. DNA–DNA hybridization results showed lower than 52 % relatedness with respect to the type strain of P. argentinensis , CH01T. These results, together with other phenotypic characteristics, support the definition of a novel species within the genus Pseudomonas , for which the name Pseudomonas punonensis sp. nov. is proposed. The type strain is LMT03T ( = LMG 26839T = CECT 8089T).

Reclassification of Agromonas oligotrophica into the genus Bradyrhizobium as Bradyrhizobium oligotrophicum comb. nov

Agromonas oligotrophica JCM 1494T was isolated in Japan in 1983, and the name was validly published in 1985. Analysis of the 16S rRNA gene sequence showed that Agromonas oligotrophica LMG 10732T ( = JCM 1494T) is located within the genus Bradyrhizobium , with Bradyrhizobium denitrificans LMG 8443T as its closest relative, showing 99.6 % 16S rRNA gene sequence identity. However, Agromonas oligotrophica LMG 10732T and Bradyrhizobium denitrificans LMG 8443T can be distinguished by housekeeping gene sequence analysis, phenotypic characterization and DNA–DNA hybridization. Agromonas oligotrophica is also genotypically and phenotypically different from the remaining species of the genus Bradyrhizobium , and we therefore propose the reclassification of Agromonas oligotrophica into the genus Bradyrhizobium as Bradyrhizobium oligotrophicum comb. nov. (type strain LMG 10732T  = JCM 1494T  = ATCC 43045T).

Nodulation in Dimorphandra wilsonii Rizz. (Caesalpinioideae), a threatened species native to the Brazilian Cerrado

The threatened caesalpinioid legume Dimorphandra wilsonii, which is native to the Cerrado biome in Brazil, was examined for its nodulation and N(2)-fixing ability, and was compared with another, less-threatened species, D. jorgei. Nodulation and potential N(2) fixation was shown on seedlings that had been inoculated singly with five bradyrhizobial isolates from mature D. wilsonii nodules. The infection of D. wilsonii by two of these strains (Dw10.1, Dw12.5) was followed in detail using light and transmission electron microscopy, and was compared with that of D. jorgei by Bradyrhizobium strain SEMIA6099. The roots of D. wilsonii were infected via small transient root hairs at 42 d after inoculation (dai), and nodules were sufficiently mature at 63 dai to express nitrogenase protein. Similar infection and nodule developmental processes were observed in D. jorgei. The bacteroids in mature Dimorphandra nodules were enclosed in plant cell wall material containing a homogalacturonan (pectic) epitope that was recognized by the monoclonal antibody JIM5. Analysis of sequences of their rrs (16S rRNA) genes and their ITS regions showed that the five D. wilsonii strains, although related to SEMIA6099, may constitute five undescribed species of genus Bradyrhizobium, whilst their nodD and nifH gene sequences showed that they formed clearly separated branches from other rhizobial strains. This is the first study to describe in full the N(2)-fixing symbiotic interaction between defined rhizobial strains and legumes in the sub-family Caesalpinioideae. This information will hopefully assist in the conservation of the threatened species D. wilsonii.

Endobacter medicaginis gen. nov., sp. nov., isolated from alfalfa nodules in an acidic soil

A bacterial strain designated M1MS02(T) was isolated from a surface-sterilized nodule of Medicago sativa in Zamora (Spain). The 16S rRNA gene sequence of this strain showed 96.5 and 96.2 % similarity, respectively, with respect to Gluconacetobacter liquefaciens IFO 12388(T) and Granulibacter bethesdensis CGDNIH1(T) from the family Acetobacteraceae. The novel isolate was a Gram-stain-negative, non-sporulating, aerobic coccoid to rod-shaped bacterium that was motile by a subpolar flagellum. The major fatty acid was C18 : 1ω7c and the major ubiquinone was Q-10. The lipid profile consisted of diphosphatidylglycerol, phosphatidylethanolamine, two aminophospholipids, three aminolipids, four glycolipids, two phospholipids and one lipid. Strain M1MS02(T) was catalase-positive and oxidase- and urease-negative. Acetate and lactate were not oxidized. Acetic acid was produced from ethanol in culture media supplemented with 2 % CaCO3. Ammonium sulphate was assimilated in glucose medium. The strain produced dihydroxyacetone from glycerol. Phylogenetic and phenotypic analyses commonly used to differentiate genera within the family Acetobacteraceae showed that strain M1MS02(T) should be classified as representing a novel species of a new genus within this family, for which the name Endobacter medicaginis gen. nov., sp. nov. is proposed. The type strain of the type species is M1MS02(T) ( = LMG 26838(T) = CECT 8088(T)). To our knowledge, this is the first report of a member of the Acetobacteraceae occurring as a legume nodule endophyte.

Cyanobacterial extracts containing microcystins affect the growth, nodulation process and nitrogen uptake of faba bean (Vicia faba L., Fabaceae)

The use of irrigation water containing cyanobacterial toxins may generate a negative impact in both yield and quality of agricultural crops causing significant economic losses. We evaluated the effects of microcystins (MC) on the growth, nodulation process and nitrogen uptake of a Faba bean cultivar (Vicia faba L., Fabaceae), particularly the effect of MC on rhizobia-V. faba symbiosis. Three rhizobial strains (RhOF4, RhOF6 and RhOF21), isolated from nodules of local V. faba were tested. The exposure of rhizobia to MC showed that the toxins had a negative effect on the rhizobial growth especially at the highest concentrations of 50 and 100 μg/l. The germination of faba bean seeds was also affected by cyanotoxins. We registered germination rates of 75 and 68.75% at the toxin levels of 50 and 100 μg/l as compared to the control (100%). The obtained results also showed there was a negative effect of MC on plants shoot, root (dry weight) and total number of nodules per plant. Cyanotoxins exposure induced a significant effect on nitrogen assimilation by faba bean seedlings inoculated with selected rhizobial strains RhOF6 and RhOF21, while the effect was not significant on beans seedling inoculated with RhOF4. This behavior of tolerant rhizobia-legumes symbioses may constitute a very important pathway to increase soil fertility and quality and can represent a friendly biotechnological way to remediate cyanotoxins contamination in agriculture.