Leguminosae native nodulating bacteria from a gold mine As-contaminated soil: Multi-resistance to trace elements,and possible role in plant growth and mineral nutrition |
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Authors: | Wesley de M. Rangel Silvia M. de Oliveira Longatti Paulo A. A. Ferreira Daiane S. Bonaldi Amanda A. Guimarães Sofie Thijs |
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Affiliation: | 1. Biology Department, Federal University of Lavras (UFLA), Lavras, Minas Gerais, Brazil;2. Soil Science Department, UFLA, Lavras, Minas Gerais, Brazil;3. Soil Department, Federal University of Santa Maria (UFSM), Santa Maria, Rio Grande do Sul, Brazil;4. Soil Science Department, UFLA, Lavras, Minas Gerais, Brazil;5. Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium |
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Abstract: | Efficient N2-fixing Leguminosae nodulating bacteria resistant to As may facilitate plant growth on As-contaminated sites. In order to identify bacteria holding these features, 24 strains were isolated from nodules of the trap species Crotalaria spectabilis (12) and Stizolobium aterrimum (12) growing on an As-contaminated gold mine site. 16S rRNA gene sequencing revealed that most of the strains belonged to the group of α-Proteobacteria, being representatives of the genera Bradyrhizobium, Rhizobium, Inquilinus, Labrys, Bosea, Starkeya, and Methylobacterium. Strains of the first four genera showed symbiotic efficiency with their original host, and demonstrated in vitro specific plant-growth-promoting (PGP) traits (production of organic acids, indole-3-acetic-acid and siderophores, 1-aminocyclopropane-1-carboxylate deaminase activity, and Ca3(PO4)2 solubilization), and increased resistance to As, Zn, and Cd. In addition, these strains and some type and reference rhizobia strains exhibited a wide resistance spectrum to β-lactam antibiotics. Both intrinsic PGP abilities and multi-element resistance of rhizobia are promising for exploiting the symbiosis with different legume plants on trace-element-contaminated soils. |
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Keywords: | plant growth-promoting biological N2 fixation trace elements multi-resistance β-lactam antibiotics resistance |
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