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1.
Microbes Environ ; 35(1)2020.
Artigo em Inglês | MEDLINE | ID: mdl-31932537

RESUMO

Vigna is a genus of legumes cultivated in specific areas of tropical countries. Species in this genus are important crops worldwide. Vigna species are of great agronomic interest in Venezuela because Vigna beans are an excellent alternative to other legumes. However, this type of crop has some cultivation issues due to sensitivity to acidic soils, high temperatures, and salinity stress, which are common in Venezuela. Vigna species establish symbioses mainly with Bradyrhizobium and Ensifer, and Vigna-rhizobia interactions have been examined in Asia, Africa, and America. However, the identities of the rhizobia associated with V. radiata and V. unguiculata in Venezuela remain unknown. In the present study, we isolated Venezuelan symbiotic rhizobia associated with Vigna species from soils with contrasting agroecosystems or from fields in Venezuela. Several types of soils were used for bacterial isolation and nodules were sampled from environments characterized by abiotic stressors, such as high temperatures, high concentrations of NaCl, and acidic or alkaline pH. Venezuelan Vigna-rhizobia were mainly fast-growing. Sequencing of several housekeeping genes showed that in contrast to other continents, Venezuelan Vigna species were nodulated by rhizobia genus including Burkholderia, containing bacteria from several new phylogenetic lineages within the genus Bradyrhizobium. Some Rhizobium and Bradyrhizobium isolates were tolerant of high salinity and Al toxicity. The stress tolerance of strains was dependent on the type of rhizobia, soil origin, and cultivation history. An isolate classified as R. phaseoli showed the highest plant biomass, nitrogen fixation, and excellent abiotic stress response, suggesting a novel promising inoculant for Vigna cultivation in Venezuela.


Assuntos
Filogenia , Proteobactérias/classificação , Proteobactérias/fisiologia , Microbiologia do Solo , Simbiose , Vigna/microbiologia , DNA Bacteriano/genética , Genes Bacterianos/genética , Fixação de Nitrogênio/genética , Proteobactérias/genética , Proteobactérias/isolamento & purificação , RNA Ribossômico 16S/genética , Nódulos Radiculares de Plantas/microbiologia , Análise de Sequência de DNA , Solo/química , Estresse Fisiológico , Venezuela , Vigna/crescimento & desenvolvimento
2.
Microbes Environ ; 35(1)2020.
Artigo em Inglês | MEDLINE | ID: mdl-31932539

RESUMO

Diverse members of Bradyrhizobium diazoefficiens, B. japonicum, and B. ottawaense were isolated from the roots of field-grown sorghum plants in Fukushima, and classified into "Rhizobia" with nodulated soybeans, "Free-living diazotrophs", and "Non-diazotrophs" by nitrogen fixation and nodulation assays. Genome analyses revealed that B. ottawaense members possessed genes for N2O reduction, but lacked those for the Type VI secretion system (T6SS). T6SS is a new bacterial weapon against microbial competitors. Since T6SS-possessing B. diazoefficiens and B. japonicum have mainly been isolated from soybean nodules in Japan, T6SS-lacking B. ottawaense members may be a cryptic lineage of soybean bradyrhizobia in Japan.


Assuntos
Biodiversidade , Bradyrhizobium/genética , Oxirredutases/genética , Sorghum/microbiologia , Sistemas de Secreção Tipo VI/deficiência , Bradyrhizobium/classificação , Bradyrhizobium/isolamento & purificação , Variação Genética , Fixação de Nitrogênio/genética , Filogenia , Nodulação/genética , Raízes de Plantas/microbiologia , Rhizobium/classificação , Rhizobium/genética , Rhizobium/isolamento & purificação , Sistemas de Secreção Tipo VI/genética
3.
World J Microbiol Biotechnol ; 36(2): 27, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31997003

RESUMO

A phosphate solubilizing bacterium ZB was isolated from the rhizosphere soil of Araucaria, which falls into the species Pantoea agglomerans. Optimization for phosphate solubilization by strain ZB was performed. At optimum culture conditions, the isolate showed great ability of solubilizing different insoluble inorganic phosphate sources viz. Ca3(PO4)2 (TCP), Hydroxyapatite (HP), CaHPO4, AlPO4, FePO4 along with rock phosphates (RPs). Inoculation with planktonic cells was found to enhance dissolved phosphorous as compared to that achieved by symplasma inoculation. Besides inoculation with different status of cells, pre-incubation could also exert a great effect on phosphate solubilization ability of P. agglomerans. When isolate ZB was cultured with glucose as carbon sources, phosphorous was more efficiently dissolved from HP and RP without pre-incubation in comparison to that obtained with pre-cultivation. Pre-cultivation, however, was more suitable for P solubilization than no pre-cultivation when bacteria were grown with xylose. A positive correlation was detected between the production of organic acids and phosphate solubilization. P. agglomerans ZB possessed many plant growth promotion traits such as N2 fixation and production of indole 3-acetic acid, phytase, alkaline phosphatase. Pot experiment showed inoculation with single isolate ZB or biofertilizer prepared from semi-solid fermentation of isolate ZB with spent mushroom substrate (SMS) compost could enhance plant growth with respect to number of leaves, plant leave area, stem diameter, root length, root dry mass, shoot dry mass and biomass when compared to the abiotic control, revealing strain ZB could be a promising environmental-friendly biofertilizer to apply for agricultural field.


Assuntos
/microbiologia , Pantoea/isolamento & purificação , Fosfatos/química , Carbono/química , Fermentação , Glucose/química , Fixação de Nitrogênio , Pantoea/metabolismo , Rizosfera , Microbiologia do Solo , Solubilidade
4.
Ecol Lett ; 23(2): 336-347, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31802606

RESUMO

The traditional view holds that biological nitrogen (N) fixation often peaks in early- or mid-successional ecosystems and declines throughout succession based on the hypothesis that soil N richness and/or phosphorus (P) depletion become disadvantageous to N fixers. This view, however, fails to support the observation that N fixers can remain active in many old-growth forests despite the presence of N-rich and/or P-limiting soils. Here, we found unexpected increases in N fixation rates in the soil, forest floor, and moss throughout three successional forests and along six age-gradient forests in southern China. We further found that the variation in N fixation was controlled by substrate carbon(C) : N and C : (N : P) stoichiometry rather than by substrate N or P. Our findings highlight the utility of ecological stoichiometry in illuminating the mechanisms that couple forest succession and N cycling.


Assuntos
Ecossistema , Fixação de Nitrogênio , China , Florestas , Nitrogênio , Fósforo , Solo , Árvores
5.
Chemosphere ; 239: 124803, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31520973

RESUMO

Nitrogen biogeochemistry occupies a central role in nitrogen cycles and exerts a significant influence on primary productivity and global carbon cycles. In order to better understand the nitrogen biogeochemistry in coastal regions, spatiotemporal nitrogen fixation, denitrification and anammox were investigated in the coastal regions of northern Beibu Gulf (NBG), South China Sea (SCS). Nitrogen fixation was mainly detected in the water column of outer bays, attributed to the low nitrate concentration and low N/P (N/P < 16). Comparisons of the nitrogen fixation rates between unicellular (<10 mm) and the filamentous diazotrophs (>10 mm) indicated that the contribution of unicellular diazotrophs was more important than filamentous diazotrophs. Besides, field investigation revealed that Richelia was the dominant species in filamentous diazotrophs. On the other hand, both denitrification and anammox were found in the surface sediment and denitrification dominated the nitrogen loss process. Denitrification was mainly related to the nitrate concentration in pore water and organic matter in the sediment, while anammox was mainly regulated by the concentration of nitrate and nitrite in pore water. Additionally, temperature, dissolved oxygen (DO) and salinity also had an impact on denitrification and anammox. The net areal yield of nitrogen biogeochemical processes was estimated to be -1079t/a, as an important pathway of nitrogen removal. This study adds to the knowledge of nitrogen biogeochemistry in the nutrient-replete coastal region and highlights its significance in such an environment.


Assuntos
Baías/química , Ciclo do Nitrogênio , Nitrogênio/química , Baías/microbiologia , Ciclo do Carbono , China , Cianobactérias/metabolismo , Desnitrificação , Nitratos/química , Nitritos/química , Nitrogênio/análise , Fixação de Nitrogênio , Oxigênio/química , Salinidade , Análise Espaço-Temporal
6.
Ecotoxicol Environ Saf ; 188: 109947, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31744624

RESUMO

Fluopyram, as a reasonably good fungicide and nematicide, is widely used to control agricultural pests worldwide. However, its effects on soil microbial communities and plant growth remain controversial. Therefore, in this study, we investigated the effects of three concentrations (0.5, 1.5, and 5.0 mg/kg) of the fluopyram (Lufuda 41.7% a.i., suspension concentrate, SC) on the pepper rhizosphere microorganisms and pepper seedlings growth in a plant growth room. Moreover, we also investigated the dissipation of fluopyram in the soil, pepper roots, and leaves across a time interval of 45 days. The results showed that fluopyram application increased the number of pepper rhizosphere phosphate (P)-solubilizing bacteria, the abundance of nitrogen (N)-fixing nifH genes, and the pepper seedling growth. The results of terminal restriction fragment length polymorphism (T-RFLP) analysis demonstrated that fluopyram did not alter rhizosphere bacterial community structure and diversity. However, fluopyram did increase the relative abundances of 138 bp and 400 bp T-RFs closely representing Bacillus and Rhizobium genera that were known as efficient plant growth promoting bacteria with P-solubilization and N-fixation properties. Corresponding to the increase of plant growth and beneficial microbes, the half-lives of fluopyram in soil and plant tissues also decreased that nevertheless suggested the role of plant-microbe interactions in the faster removal of fluopyram after application. Our results suggest that short-lived and easily degradable pesticides may have less toxicological effects on soil health while their judicious use may reshape plant-microbe interactions in favor of the plant growth.


Assuntos
Benzamidas/farmacologia , Capsicum/efeitos dos fármacos , Fungicidas Industriais/farmacologia , Bactérias Fixadoras de Nitrogênio/crescimento & desenvolvimento , Fosfatos/química , Piridinas/farmacologia , Microbiologia do Solo , Agricultura , Capsicum/crescimento & desenvolvimento , Fixação de Nitrogênio , Raízes de Plantas/química , Rizosfera , Solo/química
7.
World J Microbiol Biotechnol ; 35(11): 172, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31673798

RESUMO

The present study was designed with the objective of improving growth and nodulation of soybean [Glycine max (L.) Merill] with co-inoculation of native Bradyrhizobium sp. (LSBR-3) (KF906140) and non-rhizobial nodule endophytic diazotroph Leclercia adecarboxylata (LSE-1) (KX925974) with multifunctional plant growth promoting (PGP) traits in cereal based cropping system (Rice-Wheat). A total of 40 endophytic bacteria from cultivated and wild sp. of soybean were screened for multifarious PGP traits and pathogenicity test. Based on PGP traits, antagonistic activities and bio-safety test; L. adecarboxylata (LSE-1) was identified with 16 S rRNA gene sequencing along with the presence of nifH (nitrogen fixation) and ipdc (IAA production) genes. Dual inoculant LSE-1 and LSBR-3 increased indole acetic acid (IAA), P & Zn-solubilization, 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activity, siderophore, biofilm formation and exo-polysaccharides in contrast to single inoculation treatment. Further, assessment of dual inoculant LSBR-3 + LSE-1 improved growth parameters, nodulation, soil enzymes activities, nutrient accumulation and yield as compared to single as well as un-inoculated control treatment under field conditions. Single inoculant LSBR-3 improved yield by 8.84% over control. Further, enhancement of 4.15% grain yield was noticed with LSBR-3 + LSE-1 over LSBR-3 alone treatment. Application of LSBR-3 + LSE-1 gave superior B:C ratio (1.29) and additional income approximately 116 USD ha-1 in contrast to control treatment. The present results thus, is the first report of novel endophytic diazotroph L. adecarboxylata (LSE-1) as PGPR from Indian conditions particularly in Punjab region for exploiting as potential PGPR along with Bradyrhizobium sp. (LSBR-3) in soybean.


Assuntos
Bradyrhizobium/isolamento & purificação , Bradyrhizobium/fisiologia , Enterobacteriaceae/isolamento & purificação , Enterobacteriaceae/fisiologia , Desenvolvimento Vegetal , Raízes de Plantas/microbiologia , Soja/crescimento & desenvolvimento , Soja/microbiologia , Proteínas de Bactérias/genética , Biofilmes/crescimento & desenvolvimento , Bradyrhizobium/classificação , Bradyrhizobium/genética , Endófitos , Enterobacteriaceae/classificação , Enterobacteriaceae/genética , Fertilizantes , Ácidos Indolacéticos/metabolismo , Fixação de Nitrogênio/genética , Nutrientes , Oryza/microbiologia , Oxirredutases/genética , Filogenia , RNA Ribossômico 16S/genética , Nódulos Radiculares de Plantas/microbiologia , Sideróforos , Soja/química , Triticum/microbiologia
8.
An Acad Bras Cienc ; 91(4): e20180990, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31778453

RESUMO

The growing need for the use of clean energy has led society to seek alternatives to fossil fuels in order to less pollute the environment. Sugarcane has been known to produce enough biomass and to have associative microorganisms, such as plant growth-promoting bacteria (PGPB), which have the potential to improve the yield of crops. The objective of this study is to evaluate the efficiency and the isotopic dilution of 15N of microbial inoculants containing endophytic diazotrophic bacteria, individually inoculated and in mixture, on productivity, technological quality and biological nitrogen fixation (BNF) of sugarcane variety RB92579. The experiment was conducted for three consecutive years, comprising different crop cycles, in a completely randomized block design with four replications. The evaluations were at 11 months after planting for plant-cane, and at 12 months after cutting for ratoon cane and second ratoon cane. The contribution of BNF by 15N natural abundance technique to inoculated treatments ranged from 18% to 57.31%. This study showed that no strain promoted the improvement on yield and biological nitrogen fixation during the three cycles of sugarcane (plant-cane, ratoon cane and second ratoon cane). However, industrial characteristics of sugar cane can be affectd by PGPB inoculation.


Assuntos
Bactérias/metabolismo , Biomassa , Produtos Agrícolas , Nitrogênio/metabolismo , Saccharum/microbiologia , Endófitos , Fixação de Nitrogênio , Saccharum/crescimento & desenvolvimento
9.
Plant Sci ; 289: 110249, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31623782

RESUMO

The main objective of the present study was to characterize the symbiotic N2 fixation (SNF) capacity and to elucidate the underlying mechanisms for low-Pi acclimation in soybean plants grown in association with two Bradyrhizobium diazoefficiens strains which differ in SNF capacity (USDA110 vs. CB1809). In comparison with the USDA110-soybean, the CB1809-soybean association revealed a greater SNF capacity in response to Pi starvation, as evidenced by relative higher plant growth and higher expression levels of the nifHDK genes. This enhanced Pi acclimation was partially related to the efficient utilization to the overall carbon (C) budget of symbiosis in the CB1809-induced nodules compared with that of the USDA110-induced nodules under low-Pi provision. In contrast, the USDA110-induced nodules favored other metabolic acclimation mechanisms that expend substantial C cost, and consequently cause negative implications on nodule C expenditure during low-Pi conditions. Fatty acids, phytosterols and secondary metabolites are characterized among the metabolic pathways involved in nodule acclimation under Pi starvation. While USDA110-soybean association performed better under Pi sufficiency, it is very likely that the CB1809-soybean association is better acclimatized to cope with Pi deficiency owing to the more effective functional plasticity and lower C cost associated with these nodular metabolic arrangements.


Assuntos
Bradyrhizobium/fisiologia , Fixação de Nitrogênio , Fosfatos/deficiência , Nódulos Radiculares de Plantas/metabolismo , Soja/metabolismo , Simbiose , Nódulos Radiculares de Plantas/microbiologia , Soja/microbiologia
10.
J Environ Qual ; 48(4): 1067-1073, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31589684

RESUMO

Veterinary and growth-promoting antibiotics are widely used in animal husbandry and accumulate in manure-fertilized soils. However, the impact of these antibiotics on symbiotic nitrogen fixation is poorly understood. We investigated the effect of the veterinary antibiotics oxytetracycline and sulfamethazine, and a combination of both, on nitrogen fixation in alfalfa ( L.) inoculated with . In a pot experiment, was grown in soils fertilized with fresh manure that contained environmentally relevant antibiotic concentrations (0.2, 2, and 200 mg kg). Nodulation, nitrogen fixation, and nutrient concentrations were determined in the alfalfa plants and soils after 12 wk. Compared with the antibiotic-free control, symbiotic nitrogen fixation increased significantly in soils mixed with manure containing 2 and 200 mg kg oxytetracycline (20.1 and 20.8% increase, respectively) and a mixture of 200 mg kg oxytetracycline and sulfamethazine (12.4% increase). The measured plant- and soil-related parameters failed to explain the observed increase in nitrogen fixation. However, using concentration levels that accurately reflect common agricultural practices, we obtained results that directly contradict other experiments conducted under unrealistically high antibiotic concentrations.


Assuntos
Oxitetraciclina , Poluentes do Solo , Animais , Antibacterianos , Esterco , Fixação de Nitrogênio , Solo , Sulfametazina
11.
Environ Pollut ; 255(Pt 1): 113167, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31522008

RESUMO

Mine tailings contain toxic metals and can lead to serious pollution of soil environment. Phytoremediation using legumes has been regarded as an eco-friendly way for the rehabilitation of tailings-laden lands but little is known about the changes of microbial structure during the process. In the present study, we monitored the dynamic change of microbiota in the rhizosphere of Pongamia pinnata during a 2-year on-site remediation of vanadium-titanium magnetite tailings. After remediation, overall soil health conditions were significantly improved as increased available N and P contents and enzyme activities were discovered. There was also an increase of microbial carbon and nitrogen contents. The Illumina sequencing technique revealed that the abundance of taxa under Proteobacteria was increased and rhizobia-related OTUs were preferentially enriched. A significant difference was discovered for sample groups before and after remediation. Rhizobium and Nordella were identified as the keystone taxa at genus rank. The functional prediction indicated that nitrogen fixation was enhanced, corresponding well with qPCR results which showed a significant increase of nifH gene copy numbers by the 2nd year. Our findings for the first time elucidated that legume phytoremediation can effectively cause microbial communities to shift in favour of rhizobia in heavy metal contaminated soil.


Assuntos
Millettia/metabolismo , Proteobactérias/metabolismo , Rhizobium/crescimento & desenvolvimento , Titânio/análise , Vanádio/análise , Biodegradação Ambiental , Recuperação e Remediação Ambiental , Óxido Ferroso-Férrico , Metais Pesados/análise , Microbiota , Nitrogênio/análise , Fixação de Nitrogênio , Rizosfera , Solo/química , Microbiologia do Solo , Poluentes do Solo/análise
12.
Int J Syst Evol Microbiol ; 69(12): 3863-3877, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31486763

RESUMO

The symbioses between legumes and nitrogen-fixing rhizobia make the greatest contribution to the global nitrogen input via the process of biological nitrogen fixation (BNF). Bradyrhizobium stands out as the main genus nodulating basal Caesalpinioideae. We performed a polyphasic study with 11 strains isolated from root nodules of Chamaecristafasciculata, an annual multi-functional native legume of the USA. In the 16S rRNA gene phylogeny the strains were clustered in the Bradyrhizobium japonicumsuperclade. The results of analysis of the intergenic transcribed spacer (ITS) indicated less than 89.9 % similarity to other Bradyrhizobium species. Multilocus sequence analysis (MLSA) with four housekeeping genes (glnII, gyrB, recA and rpoB) confirmed the new group, sharing less than 95.2 % nucleotide identity with other species. The MLSA with 10 housekeeping genes (atpD, dnaK, gap, glnII, gltA, gyrB, pnp, recA, rpoB and thrC) indicated Bradyrhizobium daqingense as the closest species. Noteworthy, high genetic diversity among the strains was confirmed in the analyses of ITS, MLSA and BOX-PCR. Average nucleotide identity and digital DNA-DNA hybridization values were below the threshold of described Bradyrhizobium species, of 89.7 and 40 %, respectively. In the nifH and nodC phylogenies, the strains were grouped together, but with an indication of horizontal gene transfer, showing higher similarity to Bradyrhizobium arachidis and Bradyrhizobium forestalis. Other phenotypic, genotypic and symbiotic properties were evaluated, and the results altogether support the description of the CNPSo strains as representatives of the new species Bradyrhizobiumfrederickii sp. nov., with CNPSo 3426T (=USDA 10052T=U686T=CL 20T) as the type strain.


Assuntos
Bradyrhizobium/classificação , Chamaecrista/microbiologia , Filogenia , Nódulos Radiculares de Plantas/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , Bradyrhizobium/isolamento & purificação , DNA Bacteriano/genética , Transferência Genética Horizontal , Genes Bacterianos , Missouri , Tipagem de Sequências Multilocus , Nebraska , Fixação de Nitrogênio , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Simbiose , Temperatura Ambiente
13.
Ecology ; 100(12): e02862, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31386760

RESUMO

Increased drought intensity and frequency due to climate change may reduce the abundance and activity of nitrogen (N2 )-fixing plants, which supply new N to terrestrial ecosystems. As a result, drought may indirectly reduce ecosystem productivity through its effect on the N cycle. Here, we manipulated growing season net rainfall across a series of plots in an early successional mesic deciduous forest to understand how drought affects the aboveground productivity of the N2 -fixing tree Robinia pseudoacacia and three co-occurring nonfixing tree species. We found that lower soil moisture was associated with reduced productivity of R. pseudoacacia but not of nonfixing trees. As a result, the relative biomass and density of R. pseudoacacia declined in drier soils over time. Greater aboveground biomass of R. pseudoacacia was also associated with greater total soil N, extractable inorganic N, N mineralization rates, and productivity of nonfixing trees. These soil N effects may reflect current N2 fixation by R. pseudoacacia saplings, or the legacy effect of former trees in the same location. Our results suggest that R. pseudoacacia promotes the growth of nonfixing trees in early succession through its effect on the N cycle. However, the sensitivity of R. pseudoacacia to dry soils may reduce N2 fixation under scenarios of increasing drought intensity and frequency, demonstrating a mechanism by which drought may indirectly diminish potential forest productivity and recovery rate from disturbance.


Assuntos
Secas , Árvores , Ecossistema , Florestas , Fixação de Nitrogênio , Solo
14.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2775-2782, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418203

RESUMO

Bacteriophages infecting rhizobia of legume leads to a significant decrease in the number of rhizobia in soil and nodulation in legume, which finally affects nitrogen fixation and remarkably reduces crop yield. However, limited studies have focused on bacteriophages of rhizobia. In this study, three typic rhizobium strains of Bradyrhizobium diazoefficiens USDA110T, Sinorhizobium sojae CCBAU05684T and Sinorhizobium meliloti USDA1002T were used as the host bacteria. From each host, three rhizobiophages were isolated from an agricultural black soil with double-layer plate method. We isolated nine rhizobiophages and investigated their morphological feature and biological characteristics. The results showed that the phages of SMM (infecting Sinorhizobium meliloti USDA1002T) and BDM (infecting Bradyrhizobium diazoefficiens USDA110T) belonged to Myoviridae family, while phages of SSS (infecting Sinorhizobium sojae CCBAU05684T) belonged to Siphoviridae family. The optimal multiplicity of infection for nine phages ranged from 0.001 to 1.0. The one-step growth curve showed that the latent and rising periods of BDM were remarkably longer than that of SMM and SSS, but the bust size was minimal. Nine phages had the strongest infecting activity at 30-40 ℃ and at neutral pH condition. Comparative analysis showed that the biological characteristics of phages infected with the same host were different, with the differentiation being smaller than that of phages infected with different hosts.


Assuntos
Bacteriófagos , Bradyrhizobium , Fabaceae/microbiologia , Rhizobium/virologia , Fabaceae/virologia , Fixação de Nitrogênio
15.
Arch Microbiol ; 201(10): 1435-1446, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31428824

RESUMO

A polyphasic approach was used to infer the phylogenetic position of six nitrogen-fixing symbiotic bacteria isolated from Mimosa gymnas nodules grown in an ecotone between the Brazilian biomes of Atlantic Forest and Cerrado, considered as a hotspot of biodiversity. The 16S rRNA gene phylogeny indicated the highest similarity with Paraburkholderia oxyphila (98.7-98.9%), but similar values were found with other Paraburkholderia species. The multilocus sequence analysis (MLSA) of five (recA, gyrB, trpB, gltB, and atpD) housekeeping genes indicated that the CNPSo strains represent a novel lineage, sharing less than 95.7% of nucleotide identity (NI) with other Paraburkholderia species, being more closely related to P. nodosa. Genome parameters were analyzed for strain CNPSo 3008T, and DNA-DNA hybridization revealed a maximum of 55.9% of DNA-DNA relatedness with P. nodosa, while average nucleotide identity with the two closest species was of 93.84% with P. nodosa and of 87.93% with P. mimosarum, both parameters confirming that the strain represents a new species. In the analysis of the nodulation nodC gene, all CNPSo strains showed the highest similarity with P. nodosa, and nodulation tests indicated host specificity with Mimosa. Other phylogenetic, physiological, and chemotaxonomic properties were evaluated. All data obtained support the description of the novel species Paraburkholderia guartelaensis sp. nov., with CNPSo 3008T (= U13000T = G29.01T) indicated as the type strain.


Assuntos
Burkholderiaceae/classificação , Mimosa/microbiologia , Filogenia , Nódulos Radiculares de Plantas/microbiologia , Composição de Bases , Brasil , Burkholderiaceae/genética , Burkholderiaceae/isolamento & purificação , DNA Bacteriano/química , DNA Bacteriano/genética , Genes Bacterianos/genética , Tipagem de Sequências Multilocus , Fixação de Nitrogênio , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Especificidade da Espécie
16.
Int J Syst Evol Microbiol ; 69(11): 3448-3459, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31429819

RESUMO

Information about the symbionts of legumes of the Caesalpinioideae subfamily is still limited, and we performed a polyphasic approach with three Bradyrhizobium strains-CNPSo 3448T, CNPSo 3394 and CNPSo 3442-isolated from Chamaecrista fasciculata, a native legume broadly distributed in the USA. In the phylogenetic analysis of both the 16S rRNA gene and the intergenic transcribed spacer, the CNPSo strains were clustered within the Bradyrhizobium japonicumsuperclade. Multilocus sequence analysis with six housekeeping genes-glnII, gyrB, recA, rpoB, atpD and dnaK-indicated that Bradyrhizobium diazoefficiens is the closest species, with 83 % of nucleotide identity. In the genome analyses of CNPSo 3448T, average nucleotide identity and digital DNA-DNA hybridization results confirmed higher similarity with B. diazoefficiens, with values estimated of 93.35 and 51.50 %, respectively, both below the threshold of the same species, confirming that the CNPSo strains represent a new lineage. BOX-PCR profiles indicated high intraspecific genetic diversity between the CNPSo strains. In the analyses of the symbiotic genes nodC and nifH the CNPSo strains were clustered with Bradyrhizobium arachidis, Bradyrhizobium forestalis, Bradyrhizobium cajani, Bradyrhizobium kavangense and Bradyrhizobium vignae, indicating a different phylogenetic history compared to the conserved core genes. Other physiological (C utilization, tolerance to antibiotics and abiotic stresses), chemical (fatty acid profile) and symbiotic (nodulation host range) properties were evaluated and are described. The data from our study support the description of the CNPSo strains as the novel species Bradyrhizobiumniftali sp. nov., with CNPSo 3448T (=USDA 10051T=U687T=CL 40T) designated as the type strain.


Assuntos
Bradyrhizobium/classificação , Chamaecrista/microbiologia , Fixação de Nitrogênio , Filogenia , Nódulos Radiculares de Plantas/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , Bradyrhizobium/isolamento & purificação , DNA Bacteriano/genética , Ácidos Graxos/química , Genes Bacterianos , Missouri , Tipagem de Sequências Multilocus , Nitrogênio , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Simbiose
17.
Sci Total Environ ; 696: 134029, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31470319

RESUMO

Microorganisms in tidal freshwater wetlands affect biogeochemical cycling of nutrients, but the structures and functions of the wetland communities change due to natural and anthropogenic stresses. Soil samples were collected along a 350-m sampling belt in typical tidal freshwater wetlands of Yellow River Delta to investigate nutrient distributions, bacterial community structures and potential metabolic functions under tide and runoff stress by high-throughput sequencing and PICRUSt analysis. The total nitrogen (TN) contents varied greatly while total phosphorous (TP) contents were relatively stable. The bacterial community structures and predicted functions varied along a 350-m sampling belt. Some sulfate-reducing bacteria, nitrifying bacteria, Marmoricola, unclassified_f_Salinisphaeraceae and Oceanococcus exhibited a decreased trend with increasing distances far away from the river bank (B-0m). However, Salinisphaera was more dominant far away from the river bank (B-350m), indicating the stronger tolerance degree under salt stress. Marinobacterium and Marinobacter could be widely detected from B-0m to B-350m, demonstrating that those bacteria could tolerate a broad range of salinity and have its exceptional adaptation capacities. Redundancy analysis (RDA) indicated that nutrient and salinity played an important role in shaping bacterial community composition. NH4+-N and AP were the key factors in explaining the variance of the genus level. Predicted by PICRUSt analysis, nitrogen fixation (NF), nitrogen mineralization (NM), denitrification and dissimilatory nitrate reduction to ammonium (DNRA) might be the dominant processes of nitrogen metabolism and related genes abundance were abundant in tidal freshwater wetland soils. These findings could provide new insights into the prevention and control of potential nutrient pollution in tidal freshwater wetlands under the dual stress of tide and runoff.


Assuntos
Bactérias , Água Doce/microbiologia , Microbiota , Áreas Alagadas , China , Desnitrificação , Nitrificação , Nitrogênio , Fixação de Nitrogênio , Rios , Salinidade , Solo/química
18.
Artigo em Inglês | MEDLINE | ID: mdl-31324006

RESUMO

The inoculation of beneficial microorganisms to improve plant growth and soil properties is a promising strategy in the soil amendment. However, the effects of co-inoculation with phosphate-solubilizing bacteria (PSB) and N2-fixing bacteria (NFB) on the soil properties of typical C-deficient soil remain unclear. Based on a controlled experiment and a pot experiment, we examined the effects of PSB (M: Bacillus megaterium and F: Pseudomonas fluorescens), NFB (C: Azotobacter chroococcum and B: Azospirillum brasilence), and combined PSB and NFB treatments on C, N, P availability, and enzyme activities in sterilized soil, as well as the growth of Cyclocarya Paliurus seedlings grow in unsterilized soil. During a 60-day culture, prominent increases in soil inorganic N and available P contents were detected after bacteria additions. Three patterns were observed for different additions according to the dynamic bacterial growth. Synergistic effects between NFB and PSB were obvious, co-inoculations with NFB enhanced the accumulation of available P. However, decreases in soil available P and N were observed on the 60th day, which was induced by the decreases in bacterial quantities under C deficiency. Besides, co-inoculations with PSB and NFB resulted in greater performance in plant growth promotion. Aimed at amending soil with a C supply shortage, combined PSB and NFB treatments are more appropriate for practical fertilization at intervals of 30-45 days. The results demonstrate that co-inoculations could have synergistic interactions during culture and application, which may help with understanding the possible mechanism of soil amendment driven by microorganisms under C deficiency, thereby providing an alternative option for amending such soil.


Assuntos
Fixação de Nitrogênio , Nitrogênio/metabolismo , Fósforo/metabolismo , Microbiologia do Solo , Solo/química , Azospirillum brasilense/metabolismo , Azotobacter/metabolismo , Bacillus megaterium/metabolismo , Carga Bacteriana , China , Pseudomonas fluorescens/metabolismo
19.
Ecology ; 100(9): e02795, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31301692

RESUMO

Biological nitrogen fixation is critical for the nitrogen cycle of tropical forests, yet we know little about the factors that control the microbial nitrogen fixers that colonize the microbiome of leaves and branches that make up a forest canopy. Forest canopies are especially prone to nutrient limitation because they are (1) disconnected from soil nutrient pools and (2) often subject to leaching. Earlier studies have suggested a role of phosphorus and molybdenum in controlling biological N-fixation rates, but experimental confirmation has hitherto been unavailable. Here we present the results of a manipulation of canopy nutrient availability. Our findings demonstrate a primary role of phosphorus in constraining overall N fixation by canopy cyanobacteria, but also a secondary role of molybdenum in determining per-cell fixation rates. A conservative evaluation suggests that canopy fixation can contribute to significant N fluxes at the ecosystem level, especially as bursts following atmospheric inputs of nutrient-rich dust.


Assuntos
Microbiota , Fixação de Nitrogênio , Ecossistema , Florestas , Molibdênio , Nitrogênio , Fósforo , Solo , Árvores , Clima Tropical
20.
J Plant Res ; 132(5): 695-703, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31325057

RESUMO

The development and functioning of the nitrogen fixing symbiosis between legume plants and soil bacteria collectively called rhizobia requires continuous chemical dialogue between the partners using different molecules such as flavonoids, lipo-chitooligosaccharides, polysaccharides and peptides. Agrobacterium rhizogenes mediated hairy root transformation of legumes is widely used to study the function of plant genes involved in the process. The identification of transgenic plant tissues is based on antibiotics/herbicide selection and/or the detection of different reporter genes that usually require special equipment such as fluorescent microscopes or destructive techniques and chemicals to visualize enzymatic activity. Here, we developed and efficiently used in hairy root experiments binary vectors containing the MtLAP1 gene driven by constitutive and tissue-specific promoters that facilitate the production of purple colored anthocyanins in transgenic tissues and thus allowing the identification of transformed roots by naked eye. Anthocyanin producing roots were able to establish effective symbiosis with rhizobia. Moreover, it was shown that species-specific allelic variations and a mutation preventing posttranslational acetyl modification of an essential nodule-specific cysteine-rich peptide, NCR169, do not affect the symbiotic interaction of Medicago truncatula cv. Jemalong with Sinorhizobium medicae strain WSM419. Based on the experiments, it could be concluded that it is preferable to use the vectors with tissue-specific promoters that restrict anthocyanin production to the root vasculature for studying biotic interactions of the roots such as symbiotic nitrogen fixation or mycorrhizal symbiosis.


Assuntos
Antocianinas/fisiologia , Medicago truncatula/fisiologia , Fixação de Nitrogênio , Raízes de Plantas/fisiologia , Nódulos Radiculares de Plantas/crescimento & desenvolvimento , Simbiose , Agrobacterium/genética , Biomarcadores/análise , Medicago truncatula/genética , Medicago truncatula/crescimento & desenvolvimento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/fisiologia , Nódulos Radiculares de Plantas/microbiologia , Transformação Genética
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