Papers by Paulo Ivan Fernandes Júnior
Systematic and Applied Microbiology
Frontiers in Microbiology
Semiarid regions are apparently low biodiversity environments; however, these environments may ho... more Semiarid regions are apparently low biodiversity environments; however, these environments may host a phylogenetically diverse microbial community associated with plants. Their microbial inhabitants are often recruited to withstand stressful settings and improve plant growth under harsh conditions. Thus, plant-associated microorganisms isolated from semiarid and seasonally dry environments will be detailed in the present review, focusing on plant growth promotion potential and the microbial ability to alleviate plant abiotic stress. Initially, we explored the role of microbes from dry environments around the world, and then, we focused on seasonally dry Brazilian biomes, the Caatinga and the Cerrado. Cultivable bacteria from semiarid and seasonally dry environments have demonstrated great plant growth promotion traits such as plant hormone production, mobilization of insoluble nutrients, and mechanisms related to plant abiotic stress alleviation. Several of these isolates were able ...
Journal of Plant Growth Regulation
Journal of Soil Science and Plant Nutrition
Symbiosis
The isolation of seed-endophytic bacteria (SEB) is a promising approach for the selection of maiz... more The isolation of seed-endophytic bacteria (SEB) is a promising approach for the selection of maize plant growth-promoting bacteria (PGPB). With the hypothesis that maize seeds harbor SEB that occupy different niches and show plant-growthpromoting abilities, we aimed to isolate and characterize the potential PGPB from these seeds. The bacteria from commercial seeds (BRS Gorutuba) and axenically grown maize-seedlings were isolated, molecularly fingerprinted, and genetically characterized by amplified ribosomal DNA restriction analysis (ARDRA). All SEB were evaluated for their promotion of early root growth. The selected strains were identified by 16S rRNA sequencing and evaluated for their plant growth-promotion traits. A pot experiment was conducted to assess the ability of the SEB to promote maize-growth and nutrient accumulation. Fifty-one bacterial strains were retrieved, mostly isolated directly from the seeds. All the isolated bacteria represented different strains according to their molecular fingerprinting. ARDRA clustering revealed six clusters influenced by their plant tissue/organ of origin. Twenty-nine SEB were selected based on their influence on early root growth. The 16S rRNA sequences classified the SEB as Bacillus (22), Paenibacillus (2) and Acinetobacter (5). The inoculation of Bacillus ESA 674 improved the shoot dry mass in 57% and the Acinetobacter ESA 662 improved the root growth by 235%, both compared to the uninoculated control. At least 12 bacteria improved nutrient content in the shoots. The Bacillus spp. ESA 674 and ESA 652 outstood in improving maize nutrition by increasing the accumulation of several nutrients.
Nutrient Cycling in Agroecosystems
November 2019
This work aimed to estimate the genetic parameters of biological nitrogen fixation (BNF) in cowpe... more This work aimed to estimate the genetic parameters of biological nitrogen fixation (BNF) in cowpea to guide the development of efficient cultivars in N2 fixation. Inoculation was performed with a mix of three Bradyrhizobium strains. Two soil inoculations were performed with 1mL of the inoculum, at sowing and at five days after seedlings emergence. Plants were harvested and evaluated at 40 days after sowing. The means and variances of parents F1 and F2 and the BCs IC-1 (inefficient) × BRS Marataoã (efficient) (cross 1) and IC-1 × BRS Pujante (efficient) (cross 2) were analyzed. Segregation analyses for efficient and non-efficient plants indicate that BNF is controlled by two genes with dominant-recessive epistatic effect. Narrow-sense heritability estimates for crosses 1 and 2 were, respectively, 90% and 78% for shoot dry matter (SDM); 78% and 58%, for number of nodules/plant (NN); 86% and 58%, for nodule fresh matter (NFM); and 85% and 71%, for accumulated nitrogen (AN). Gene number...
Journal of Soil Science and Plant Nutrition
Pesquisa Agropecuária Brasileira
: The objective of this work was to assess the efficiency of the inoculation of a diazotrophic ba... more : The objective of this work was to assess the efficiency of the inoculation of a diazotrophic bacterial consortium by the drip irrigation system into sugarcane (Saccharum spp.), in the Brazilian semiarid region. The evaluated treatments were: standard inoculation by submersion; one or two inoculations by drip irrigation; nitrogen (urea) applied by fertigation; and negative controls, without inoculation or nitrogen fertilization. Leaf gas exchanges and plant growth and yield were assessed. Inoculation by irrigation is efficient for all variables, and double inoculation by the drip irrigation system stands out, increasing stem yield in 16% when compared with the negative control, without differing from the treatment with nitrogen fertilizer.
Crop and Pasture Science
The study of plant growth-promoting bacteria (PGPB) can identify outstanding bacteria for crops. ... more The study of plant growth-promoting bacteria (PGPB) can identify outstanding bacteria for crops. For forage grasses adapted to drylands, the selection of PGPB can increase the field performance of pastures. The aim of this study was to isolate, and characterise at molecular, biochemical and symbiotic levels, diazotrophic bacteria obtained from buffel grass (Cenchrus ciliaris), sorghum (Sorghum bicolor) and Tifton 85 (Cynodon spp.) from Brazilian semi-arid region fields. Field-grown plants were collected, and the roots were surface-disinfected, crushed and inoculated in a semi-solid medium. After the formation and confirmation of microaerophilic pellicles, the bacteria were isolated and purified. All bacterial isolates were subjected to nifH gene amplification and identified by their partial 16S rRNA gene sequences. The bacteria were evaluated for the production of auxins and siderophores, calcium phosphate solubilisation, and diazotrophic ability as ‘in vitro’ plant growth-promotion...
Revista de Ciências Agrárias
Forage legumes are important resources in semiarid regions due to their abilities to adapt to soi... more Forage legumes are important resources in semiarid regions due to their abilities to adapt to soils with low fertility and fix nitrogen when associated with diazotrophic bacteria. Here, we applied a polyphasic approach to characterize a set of legume nodule isolates obtained from Clitoria ternatea and Stylosanthes capitata cultivated in the soils of a semiarid region of Brazil. A total of 126 bacterial isolates were obtained: 45 isolates from C. ternatea and 81 isolates from S. capitata. Nodulation tests revealed only ten isolates that nodulated their original host: six isolates from C. ternatea and four isolates from S. capitata. These ten legume nodule isolates were phenotypically and genotypically characterized. All isolates grew in fructose, glucose, sodium glutamate, maltose, xylose, and sucrose. Metabolic tests showed a relationship between tolerance to salt and high temperatures, where isolates that tolerated the highest salt concentration also tolerated the highest temperature. Three isolates showed amylolytic activity, and four isolates showed carboxymethyl cellulolytic activity. Streptomycin was the most limiting and nalidixic acid was the least limiting antibiotic to bacterial growth. Seven out of ten isolates were indol-acetic acid producers. Additionally, 16S rRNA gene partial sequencing enabled the identification of members of the genera Bacillus (1), Bradyrhizobium (4), Leifsonia (3), Microvirga (1), and Rhizobium (1). These data reveal phenotypically and genotypically diverse bacteria inhabiting the nodules of the forage legumes C. ternatea and S. capitata represent an important microbial source to protect new biotechnological products and improve forage legumes in semiarid regions.
World Journal of Microbiology and Biotechnology
Sorghum [Sorghum bicolor (L.) Moench] is a multipurpose grass cultivated in drylands due to its a... more Sorghum [Sorghum bicolor (L.) Moench] is a multipurpose grass cultivated in drylands due to its adaptation to drought. However the characteristics of sorghum-associated bacteria are not known in the Brazilian drylands. The aim of this study was to isolate and evaluate the plant growth promotion potential bacteria from field-grown sorghum under two irrigation and manure application levels in a Brazilian semi-arid reagion. Sorghum was irrigated with 3 or 1 mm day and fertilized or not with liquid goat manure. Bacteria were obtained from surface-disinfected roots applying two nitrogen-free semi-solid media. The bacteria were evaluated for the presence of nifH gene, 16S rRNA sequences, calcium-phosphate solubilization, production of auxins and siderophores and for sorghum growth promotion. We obtained 20 out of 24 positive bacteria for nifH. The isolates were classified as in six different genera. All isolates produced auxins "in vitro", six bacteria produced siderophores and three Enterobacteriaceae solubilized calcium-phosphate. At least ten bacteria resulted in the increased total N content in the sorghum shoots, comparable to fertilization with 50 mg N plant week and to inoculation with Azospirillum brasilense Ab-V5. Enterobacter sp. ESA 57 was the best sorghum plant-growth promoting bacteria isolated in this study.
Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology], Jan 2, 2018
Erythrina velutina ("mulungu") is a legume tree from Caatinga that associates with rhiz... more Erythrina velutina ("mulungu") is a legume tree from Caatinga that associates with rhizobia but the diversity and symbiotic ability of "mulungu" rhizobia are poorly understood. The aim of this study was to characterize "mulungu" rhizobia from Caatinga. Bacteria were obteined from Serra Talhada and Caruaru in Caatinga under natural regeneration. The bacteria were evaluated to the amplification of nifH and nodC and to metabolic characteristics. Ten selected bacteria identified by 16S rRNA sequences. They were tested in vitro to NaCl and temperature tolerance, auxin production and calcium phosphate solubilization. The symbiotic ability were assessed in an greenhouse experiment. A total of 32 bacteria were obtained and 17 amplified both symbiotic genes. The bacteria showed a high variable metabolic profile. Bradyrhizobium (6), Rhizobium (3) and Paraburkholderia (1) were identified, differing from their geographic origin. The isolates grew up to 45°C to 0.51...
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Papers by Paulo Ivan Fernandes Júnior