Rhizobial characterization in revegetated areas after bauxite mining

Abstract

Little is known regarding how the increased diversity of nitrogen-fixing bacteria contributes to the productivity and diversity of plants in complex communities. However, some authors have shown that the presence of a diverse group of nodulating bacteria is required for different plant species to coexist. A better understanding of the plant symbiotic organism diversity role in natural ecosystems can be extremely useful to define recovery strategies of environments that were degraded by human activities. This study used ARDRA, BOX-PCR fingerprinting and sequencing of the 16S rDNA gene to assess the diversity of root nodule nitrogen-fixing bacteria in former bauxite mining areas that were replanted in 1981, 1985, 1993, 1998, 2004 and 2006 and in a native forest. Among the 12 isolates for which the 16S rDNA gene was partially sequenced, eight, three and one isolate(s) presented similarity with sequences of the genera Bradyrhizobium, Rhizobium and Mesorhizobium, respectively. The richness, Shannon and evenness indices were the highest in the area that was replanted the earliest (1981) and the lowest in the area that was replanted most recently (2006).

Characterization of Rhizobia and Arbuscular Mycorrhizal Fungi in Areas Impacted by Gravel Mining in Brazil

“…Therefore, the symbiosis with arbuscular mycorrhizal fungi is essential for plant growth by giving the plant access to poorly soluble, lowdiffusion nutrientes, such as phosphorus, through hyphal networks (REINHARDT, 2007;PARNISKE, 2008). Thus, this tripartite symbiosis may favor the establishment and development of plants in areas with physical, chemical, or biological edaphic problems (RODRIGUES et al, 2006;BORGES et al, 2016).…”

Plant growth‐promoting rhizobacterial communities from an area under the influence of iron mining and from the adjacent phytophysiognomies which have high genetic diversity

“…Changes caused by mining influence the diversity and density of soil organisms, affecting biochemical processes that are essential for sustainability of the ecosystems (Borges et al, 2016;Escobar et al, 2015;Silva et al, 2018). Among these processes, we emphasize biological nitrogen fixation (BNF), carried out by symbiotic and associative diazotrophic bacteria, which is extremely important for the ecosystems by making nitrogen available in a form that can be assimilated by plants, which promotes greater plant development.…”

“…Microbial diversity in the soil, especially in tropical soils, is a good indicator of environmental changes (Borges et al, 2016;Bruce et al, 2010;Castro et al, 2016). In addition, it represents genetic resources with potential for biotechnological application, such as plant growthpromoting rhizobacteria (PGPR).…”

“…In addition, it represents genetic resources with potential for biotechnological application, such as plant growthpromoting rhizobacteria (PGPR). These bacteria can be isolated directly from nodules on plants found in the environment under study (Moreira et al, 1993;Moreira et al, 1998;Santos et al, 2017) or indirectly through the use of promiscuous species of trap plants, such as Macroptilium artropurpureum (Borges et al, 2016;Jesus et al, 2005;Lima et al, 2009), Mimosa tenuiflora (Silva et al, 2017), Vigna unguiculata (Castro et al, 2017), Phaseolus vulgaris (Dall'Agnol et al, 2016), Glycine max (Ribeiro et al, 2015), and other species.…”

“…Although many studies have shown that changes in soil use spur changes in the genotypic and functional diversity of the organisms under different plant covers (Borges et al, 2016;Castro et al, 2016;Jaramillo et al, 2013), these kinds of studies related to diversity of microorganisms in iron mining areas are scarce (Cao et al, 2015;Castro et al, 2017;Matias et al, 2009;Teixeira et al, 2017;Vieira et al, 2017). Considering the degradation of large areas by iron ore mining as well as the environmental relevance of biological N 2 fixation for recovery of these areas, the aim of this study was to evaluate the symbiotic and non-symbiotic efficiency of native PGPR communities from an area in recovery after modifications by iron mining and from adjacent phytophysiognomies, using Macroptilium atropurpureum as a trap plant in two climate seasons (dry and rainy), and to make correlations with the chemical and physical attributes of the soil.…”