Genetic and biochemical characterization of rhizobacterial strains and their potential use in combination with chelants for assisted phytoremediation

Abstract

Copper and zinc are essential micronutrients in plants but, at high concentrations, they are toxic. Assisted phytoremediation is an emerging "green" technology that aims to improve the efficiency of tolerant species to remove metals from soils through the use of chelants or microorganisms. Rhizobacteria can promote plant growth and tolerance and also affect the mobility, bioavailability, and complexation of metals. A pot experiment was conducted to evaluate the phytoremediation effectiveness of sunflowers cultivated in a Cu- and Zn-spiked soil, in the presence or absence of bacterial consortium and/or chelants. The consortium was constituted of two Stenotrophomonas maltophilia strains and one of Agrobacterium sp. These strains were previously isolated from the rhizosphere of maize plants cultivated on a metal-polluted soil and here molecularly and biochemically characterized. Results showed that the consortium improved sunflower growth and biomass production on the spiked soils. Sunflowers accumulated large amounts of metals in their roots and leaves; however, neither the bacterial consortium nor the chelants, singularly added to pots, influenced significantly Cu and Zn plant uptake. Furthermore, the consecutive soil amendment with the EDTA and bacterial consortium determined a consistent accumulation of metals in sunflowers, and it might be an alternative strategy to limit the use of EDTA and its associated environmental risks in phytoremediation.

Molecular Characterization of Copper Resistance Bacterial Strains and its Optimization Using Statistical Methods

“…In order to determine the integrity of isolate JRHM33, different biochemical tests were performed, including an oxidase test, a catalase test, an indole production test, a Voges Proskauer test, a Urease test, and a citrate test. 16…”

Application of Multi-Plant Symbiotic Systems in Phytoremediation: A Bibliometric Review

“…Therefore, future phytoremediation mechanisms must be examined from multiple perspectives in both the above and belowground portions. (3) Future trends include the use of additives [e.g., plant growth regulators (PGR) [122], organic improvers [123], inorganic improvers [124], chelating agents [125], microorganisms [arbuscular mycorrhizal fungi (AMF), plant-growth-promoting rhizobacteria (PGPR)] [126][127][128], and other means to assist multi-plant combination restoration techniques. (4) Molecular, breeding, and biotechnology are also important ways to improve the efficiency of multiplant assemblages for remediation, reduce remediation time, and speed up ecosystem recovery by targeting transgenic plants that improve plant-microbe interactions or rhizosphere microbial activity, thereby promoting positive plant-plant benefits.…”

Plant Growth Promoting Microorganisms Useful for Soil Desalinization

“…It has been recognized that a relevant role to maintain and improve plant health is played by rhizosphere microorganisms colonizing the fine plant roots. The new-generation sequence (NGS) technique, able to sequence up to the whole genome of every kind of living being, has revealed an unknown world of microorganisms that inhabit the rhizosphere, and many of them carry out the function of plant growth promoters (PGP microorganisms), reducing either biotic or abiotic stresses, such as that caused, for instance, by soil salinization [3]. The tolerance to high salt concentrations of certain microorganism strains and their capability to improve the plant wellness have been demonstrated by several studies, also reported in this Special Issue, which, in fact, has collected papers focused on the interactions among plants and microorganisms when they are exposed to salty and/or arid soil.…”