Biotechnological potential of plant growth-promoting bacteria from the roots and rhizospheres of endemic plants in ironstone vegetation in southeastern Brazil
Microorganisms associated with plants have a great biotechnological potential, but investigations of these microorganisms associated with native plants in peculiar environments has been incipient. The objective of this study was to analyze the plant growth-promoting bacteria potential of cultivable bacteria associated with rare plants from the ferruginous rocky fields of the Brazilian Iron Quadrangle. The roots and rhizospheres of nine endemic plants species and samples of a root found in a lateritiric duricrust (canga) cave were collected, the culturable bacteria isolated and prospected for distinct biotechnological and ecological potentials. Out of the 148 isolates obtained, 8 (5.4%) showed potential to promote plant growth, whereas 4 (2.7%) isolates acted as biocontrol agents against Xanthomonas citri pathotype A (Xac306), reducing the cancrotic lesions by more than 60% when co-inoculated with this phytopathogen in Citrus sinensis plants. Moreover, other 4 (2.7%) isolates were classified as potential bioremediation agents, being able to withstand high concentrations of arsenite (5 mM As3+) and arsenate (800 mM As5+), by removing up to 35% and 15% of this metalloid in solution, respectively. These same four isolates had a positive influence on the growth of both the roots and the aerial parts when inoculated with tomato seeds in the soil contaminated with arsenic. This is the first time that an investigation highlights the potentialities of bacteria associated with rare plants of ferruginous rocky fields as a reservoir of microbiota of biotechnological and ecological interest, highlighting the importance of conservation of this area that is undergoing intense anthropic activity.
KeywordsCanga Rare plants Bioremediation Biocontrol Biofertilization Plant growth-promoting bacteria
Thanks to all members of the Laboratory of Biochemistry and Molecular Biology (LBBM, Federal University of Ouro Preto, UFOP) for their support. Thanks to the NanoLab Laboratory of the Department of Metalurgy of Mines, Federal University of Ouro Preto, for SEM and EDS analysis.
EBF, LMM, FFC, and LHYK designed the work and selected the plant samples investigated. EBF, WLC, LMM, FFC, LHYK, and CGCL collected the plant samples. EBF, ITV, WLC, IFC, RABA, CGCL, NPF, and ABS performed all biochemical assays. EBF, JAF, JCCC, and CGCL performed the experiments in Citrus plants. EBF, LMM, ITV, FFC, CCMG, and LHYK interpreted findings. EBF and LMM wrote the paper. ITV, WLC, IFC, RABA, CGCL, NPF, ABS, JAF, JCCC, FFC, CCMG and LHYK contributed additional interpretations and general manuscript comments. EBF, LMM, RABA, and ABS revised the paper.
This work was supported by the following agencies: the National Council of Technological and Scientific Development (CNPq Process 481226/2013-3), Foundation of Protection to Research of the State of Minas Gerais—FAPEMIG (process APQ-02387-14), and Coordination for the Improvement of Higher Education Personnel (CAPES) (the BIGA Project, CFP 51/2013, process 3385/2013).
Compliance with ethical standards
Conflict of interest
The authors declare that there are no conflict of interest.
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