Assessing nickel tolerance of bacteria isolated from serpentine soils

Abstract

Serpentine soils present unique characteristics such as a low Ca/Mg ratio, low concentration of nutrients, and a high concentration of heavy metals, especially nickel. Soil bacterial isolates from an ultramafic complex located in the tropical savanna known as the Brazilian Cerrado were studied. Nickel-tolerant bacteria were obtained, and their ability to remove nickel from a culture medium was assessed. Bacterial isolates presented higher tolerance to nickel salts than previously reported for bacteria obtained from serpentine environments in other regions of the world. In addition, the quantification of nickel in cell pellets indicated that at least four isolates may adsorb soluble forms of nickel. It is expected that information gathered in this study will support future efforts to exploit serpentine soil bacteria for biotechnological processes involving nickel decontamination from environmental samples.

Potential of Rhizobia Nodulating Anthyllis vulneraria L. from Ultramafic Soil as Plant Growth Promoting Bacteria Alleviating Nickel Stress in Arabidopsis thaliana L.

“…Application of PGP rhizobia increase plant survival in the presence of hazardous levels of metals mainly by counteracting biomass decrease by improved mineral nutrition and secretion of phytohormones, enhance the production of plant growth regulators (auxins, gibberellins, cytokinins), and stimulate photosynthesis and antioxidant activity [ 13 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Moreover, rhizobia also support plant adaptation to metal-polluted sites through chelation of the metals in the soils [ 14 , 29 , 33 ]. It has been shown that ultramafic soil bacteria are tolerant to nickel [ 33 , 34 ], and they exhibit species-unique cellular response mechanisms under stress conditions [ 29 , 34 ].…”

“…Moreover, rhizobia also support plant adaptation to metal-polluted sites through chelation of the metals in the soils [ 14 , 29 , 33 ]. It has been shown that ultramafic soil bacteria are tolerant to nickel [ 33 , 34 ], and they exhibit species-unique cellular response mechanisms under stress conditions [ 29 , 34 ]. The exopolysaccharides and siderophores secreted by rhizobia immobilize toxic ions and help maintain ionic balance in the rhizosphere [ 29 , 32 , 33 , 34 ].…”

“…It has been shown that ultramafic soil bacteria are tolerant to nickel [ 33 , 34 ], and they exhibit species-unique cellular response mechanisms under stress conditions [ 29 , 34 ]. The exopolysaccharides and siderophores secreted by rhizobia immobilize toxic ions and help maintain ionic balance in the rhizosphere [ 29 , 32 , 33 , 34 ]. Moreover, the use of rhizobia in combination with plants is expected to minimize stress reactions in plants colonizing metal-polluted soils and provide high efficiency for phytoremediation (the use of plants to extract and remove pollutants) [ 29 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ].…”

Enhanced bio-recovery of aluminum from low-grade bauxite using adapted fungal strains

“…Fungal metal tolerance varies from strain to strain depending on their sources or sites of isolation, their competence to the toxicity of the specific metal, and also its concentration [30,31]. However, mostly indigenous fungal strains isolated from heavy metal-contaminated sites are extensively studied to get the metal-resistant strains showing significant tolerance for high heavy metal concentrations [32][33][34].…”