Diversity and Efficiency of Rhizobia from a Revegetated Area and Hotspot-Phytophysiognomies Affected by Iron Mining as Indicators of Rehabilitation and Biotechnological Potential.

This study aimed to evaluate the resilience of phytophysiognomies under influence of iron mining by assessing the occurrence, diversity, and symbiotic efficiency of native communities of nitrogen-fixing bacteria that nodulate leguminous plants (rhizobia) in soils of an area revegetated with grass after iron mining activities and in the phytophysiognomies in adjacent areas (Canga, Atlantic Forest, Cerrado, and Eucalyptus-planted forest). Experiments for capturing rhizobia through two species of promiscuous plants, siratro (Macroptilium atropurpureum) and cowpea (Vigna unguiculata), were conducted in a greenhouse. The rhizobial strains isolated were characterized phenotypically, genetically (16S rRNA sequencing and BOX-PCR fingerprinting), and regard symbiotic efficiency of biological nitrogen fixation (BNF) compared to mineral nitrogen and reference strains.

Chemical, physical, and biological attributes in soils affected by deposition of iron ore tailings from the Fundão Dam failure.

Monitoring degraded areas is essential for evaluation of the quality of the rehabilitation process. In this study, we evaluate how the physical and chemical characteristics of the mixture of iron ore tailings with the soil have affected the soil microbial biomass and activity in areas along the Gualaxo do Norte River after the Fundão Dam disaster. Composite soil samples were collected from areas that were impacted (I) and not impacted (NI) by the tailings.

Rhizobia and endophytic bacteria isolated from rainforest fragments within an iron ore mining site of the Eastern Brazilian Amazon.

The aim of the present study was to isolate and evaluate the diversity of rhizobial and endophytic bacterial strains from undisturbed native rainforests within an iron ore mining site of the Serra Norte de Carajás in the Eastern Brazilian Amazon region to assess their biotechnological utility in reclamation of areas. Experiments were conducted to capture strains from samples of the soil of these forests at the sites Arenito II, Noroeste II, and Sul IV using Macroptilium atropurpureum and Mimosa acutistipula var. ferrea as trap host plants.

Bradyrhizobium campsiandrae sp. nov., a nitrogen-fixing bacterial strain isolated from a native leguminous tree from the Amazon adapted to flooded conditions.

The nitrogen-fixing bacterial strain UFLA 01-1174 was isolated from nodules of Campsiandra laurilifolia Benth. originating from the Amazon region, Brazil. Its taxonomic position was defined using a polyphasic approach.

Bradyrhizobium uaiense sp. nov., a new highly efficient cowpea symbiont.

This study describes two Bradyrhizobium strains, UFLA03-164 and UFLA03-153, which share more than 99% sequence similarity of the 16S rRNA with the type strains of 15 species in this genus. The concatenation of three housekeeping genes (recA, gyrB, and dnaK) indicated that both strains formed a single clade separate from known Bradyrhizobium species. B.

Classification of the inoculant strain of cowpea UFLA03-84 and of other strains from soils of the Amazon region as Bradyrhizobium viridifuturi (symbiovar tropici).

Cowpea (Vigna unguiculata L.) is a legume species that considerably benefits from inoculation with nitrogen fixing bacteria of the genus Bradyrhizobium. One of the strains recommended for inoculation in cowpea in Brazil is UFLA03-84 (Bradyrhizobium sp.

Bradyrhizobium forestalis sp. nov., an efficient nitrogen-fixing bacterium isolated from nodules of forest legume species in the Amazon.

Three strains of nitrogen-fixing bacteria isolated from nodules of Inga sp. (INPA54B) and Swartzia sp. (INPA86A and INPA01-91A) in soils under native forest in the Brazilian Amazon were previously identified as belonging to the Bradyrhizobium genus.

Tripartite symbiosis of Sophora tomentosa, rhizobia and arbuscular mycorhizal fungi.

Sophora tomentosa is a pantropical legume species with potential for recovery of areas degraded by salinization, and for stabilization of sand dunes. However, few studies on this species have been carried out, and none regarding its symbiotic relationship with beneficial soil microorganisms. Therefore, this study aimed to evaluate the diversity of nitrogen-fixing bacteria isolated from nodules of Sophora tomentosa, and to analyze the occurrence of colonization of arbuscular mycorrhizal fungi on the roots of this legume in seafront soil.

Bradyrhizobium brasilense sp. nov., a symbiotic nitrogen-fixing bacterium isolated from Brazilian tropical soils.

Four strains of rhizobia isolated from nodules of Vigna unguiculata (UFLA03-321, UFLA03-320 and UFLA03-290) and Macroptilium atropurpureum (UFLA04-0212) in Brazilian soils were previously reported as a new group within the genus Bradyrhizobium. To determine their taxonomic position, these strains were characterized in this study using a polyphasic approach. The analysis of the 16S rRNA gene grouped the four strains with Bradyrhizobium pachyrhizi PAC48.

High diversity of Bradyrhizobium strains isolated from several legume species and land uses in Brazilian tropical ecosystems.

The genus Bradyrhizobium stands out among nitrogen-fixing legume-nodulating bacteria because it predominates among the efficient microsymbionts of forest, forage, and green manure legume species, as well as important species of grain legumes, such as soybean, cowpea, and peanut. Therefore, the diversity of Bradyrhizobium strains is a relevant resource from environmental and economic perspectives, and strains isolated from diverse legume species and land uses in Brazilian tropical ecosystems were assessed in this study. To accomplish this, sequences of four housekeeping genes (atpD, dnaK, gyrB, and recA) were individually analysed, with the first three also being considered using multilocus sequence analysis (MLSA).

Soil biological attributes in arsenic-contaminated gold mining sites after revegetation.

Recovery of arsenic contaminated areas is a challenge society faces throughout the world. Revegetation associated with microbial activity can play an essential role in this process. This work investigated biological attributes in a gold mining area with different arsenic contents at different sites under two types of extant revegetation associated with cover layers of the soil: BS, Brachiaria sp.

Genetic and symbiotic diversity of nitrogen-fixing bacteria isolated from agricultural soils in the western Amazon by using cowpea as the trap plant.

Cowpea is a legume of great agronomic importance that establishes symbiotic relationships with nitrogen-fixing bacteria. However, little is known about the genetic and symbiotic diversity of these bacteria in distinct ecosystems. Our study evaluated the genetic diversity and symbiotic efficiencies of 119 bacterial strains isolated from agriculture soils in the western Amazon using cowpea as a trap plant.