Expression Changes in Metal-Resistance Genes in Microbacterium liquefaciens Under Nickel and Vanadium Exposure

Abstract

Microbacterium liquefaciens MNSH2-PHGII-2 is a nickel-vanadium-resistant bacterium isolated from mine tailings located in Guanajuato, Mexico. In PHGII liquid media, M. liquefaciens has the ability to remove 29.5 ppm of Ni and 168.3 ppm of V. The present study reports, for the first time in M. liquefaciens, the presence of the genes nccA (Ni-Co-Cd resistance), hant (high-affinity nickel transporter), smtA, a metal-binding protein gene, and VAN2 (V resistance), which showed an increased expression under exposure to 200 ppm of Ni and 200 ppm of V during the logarithmic growth phase of the microorganism in PHGII liquid media. Data about the expression profile of genes conferring metal resistance to M. liquefaciens can improve the knowledge of those mechanisms involved in the processes of Ni-V resistance and probably in Ni-V removal processes. Based on our data, we can suggest that M. liquefaciens has the potential to be used in the biological treatment of toxic wastes with high Ni and V content.

(NH4)2[Ni(H2O)6]2V10O28 ⋅ 4H2O; Structural Analysis and Bactericidal Activity against Pathogenic Gram Negative Bacteria

“…A detailed study revealed the effects of nickel and vanadium uptake by M. liquefaciens. [3] Nickel and vanadium at low concentrations are indispensable for several bacterial cellular processes, but higher concentrations of nickel and vanadium introduce cytotoxicity. [53] The resistance mechanisms to metal excesses in bacteria include bioaccumulation, ion internalization/ externalization and biosorption.…”

“…[53] The genetic mechanisms that regulate the genetic expression pathways are not well understood, but the overexpression of these genes in response to nickel and vanadium are important for their metabolism in M. liquefaciens allowing for bacterial survival. [3] Nickel and vanadium were reported to enter the cell via several transporters, e. g. nccA, hant, and VAN2 before incorporating these metal ions into enzymes, metalloproteins and storage reservoirs and interacting reversibly with metalloregulators. [54][55][56][57][58]…”

“…Nickel is involved in several enzymes, e. g. NiÀ Fe hydrogenase, urease, acetyl-CoA decarbonylase/synthase, CO dehydrogenase, various superoxide dismutases, methyl coenzyme M reductase, methylenediurease, some glyoxylases and aci-reductone dioxygenase. [1][2][3] Several types of Gram negative bacteria {Cupriavidus metallidurans [4] and Helicobacter pylori [5] } are able to sense the cellular Ni(II) concentration and taking it up as nutrient, nevertheless there is no Ni(II) based drugs available and the Ni(II) complexes have rarely been in-vitro investigated as the antibacterial agents. [6] On the other hand, there are vanadium compounds acting as inorganic cofactors in alternative nitrogenases and haloperoxidases, inhibitors of tyrosine kinases and phosphatases, anticancer agents and insulin mimetic agents akin to Diabetes mellitus.…”

Vanadium in the Environment: Biogeochemistry and Bioremediation

“…145 In another aspect, intracellular reactive oxygen species (ROS) are generated during V(V) bioreduction, 146 doing harm to microbes, which triggers a detoxification process by ROSscavenging enzymes such as superoxide dismutase and catalase. 130 Additionally, V-resistance genes were gradually discovered, such as van2, czcD, cnrB2, and smtAB, 147,148 which help microorganisms survive in V-existing environments. Microbial catalysis can improve the V(V)-reduction efficacy of a substance.…”

Evaluación de la peligrosidad de los elementos potencialmente tóxicos presentes en residuos mineros abandonados

“…Asimismo, este elemento es altamente valorado por la industria de la fabricación de aleaciones (con Fe, Cu, Cr y Zn) por lo que la minería del Ni aporta residuos principalmente por la extracción y beneficio de minerales de pentlandita (Ni,Fe)9S8, millerita (NiS), NiSb, NiAs2, NiAsS, NiSbS y garnierita (Si4O13[Ni, Mg]2•2 H2O) [28], [54]. [87].…”