Effect of Zn(II) on the reduction and accumulation of Cr(VI) by Arthrobacter species

Abstract

Natural habitats are often characterized by the coexistence of Zn and Cr. This study assessed the potential of two Gram-positive, Cr(VI)-reducing, aerobic bacterial strains belonging to Arthrobacter genera, which were isolated from basalt samples taken from the most polluted region of the Republic of Georgia, to remediate Cr(VI) in environments in the presence of Zn(II). Our batch experiments revealed that the addition of Zn(II) to the tested bacterial cells significantly enhanced the accumulation of Cr. According to electron spin resonance (ESR) measurements, the presence of Zn(II) ions did not change the nature of Cr(V) and Cr(III) complexes generated during the microbial reduction of Cr(VI). The efficiency of Cr(VI) reduction also remained unchanged after the addition of 50 mg/l of Zn(II) to the bacterial cells. However, at high concentrations of Zn(II) (higher than 200 mg/l), the transformation of Cr(VI) to Cr(V) and Cr(III) complexes decreases significantly. In addition, it was shown that the accumulation pattern of Zn in the tested bacterial species in the presence of 100 mg/l of Cr(VI) fits the Langmuir-Freundlich model well. The two tested bacterial strains exhibited different characteristics of Zn accumulation.

Synthesis of silver nanoparticles using Peganum harmala extract as a green route

“…However, the use of toxic chemicals as reducing agents in many of these processes, which is potentially dangerous to the environment and biological systems, is of great concern (5,6). Compared with other methods, biological methods using microorganisms (7,8), enzymes (9), and plants or plant extracts like Nothapodytes nimmoniana (Graham) Mabb. fruit extracts (10), Alternanthera dentate aqueous extract, Acorus calamus and Boerhaavia diffusa plant extracts (11), Allophylus serratus leaf and leaf-derived callus extracts (12) are environmentally friendly and alternatives to chemical and physical methods for the synthesis of AgNPs (13).…”

Creation of Silver-Gold Alloy Nanoparticles Using Citrus sinensis Peel Extract and Their Antibacterial Efficacy

“…Currently, modified or synthesized NPs are extensively used in industrially produced products, such as skin care products, electronics, and textiles. Metallic nanoparticles have been produced via a variety of physical and chemical processes including spray pyrolysis, phase transfer, digestive ripening, and co-reduction of metal reactions [1][2].…”