Effects of Nickel Nanoparticles on Rhodococcus Cell Surface Morphology and Nanomechanical Properties

Abstract

Nickel nanoparticles (NPs) are used for soil remediation and wastewater treatment due to their high adsorption capacity against complex organic pollutants. However, despite the growing use of nickel NPs, their toxicological towards environmental bacteria have not been sufficiently studied. Actinobacteria of the genus Rhodococcus are valuable bioremediation agents degrading a range of harmful and recalcitrant chemicals. Both positive and negative effects of metal ions and NPs on the biodegradation of organic pollutants by Rhodococcus were revealed, however, the mechanisms of such interactions, in addition to direct toxic effects, remain unclear. In the present work, the influence of nickel NPs on the viability, surface topology and nanomechanical properties of Rhodococcus cells have been studied. Bacterial adaptations to high (up to 1.0 g/L) concentrations of nickel NPs during prolonged (24 and 48 h) exposure were detected using combined confocal laser scanning and atomic force microscopy. Incubation with nickel NPs resulted in a 1.25–1.5-fold increase in the relative surface area and roughness, changes in cellular charge and adhesion characteristics, as well as a 2–8-fold decrease in the Young’s modulus of Rhodococcus ruber IEGM 231 cells. Presumably, the treatment of rhodococcal cells with sublethal concentrations (0.01–0.1 g/L) of nickel NPs facilitates the colonization of surfaces, which is important in the production of immobilized biocatalysts based on whole bacterial cells adsorbed on solid carriers. Based on the data obtained, cell surface functionalizing with NPs is possible to enhance adhesive and catalytic properties of bacteria suitable for environmental applications.

Polyphosphate accumulation and cell-surface properties by autochthonous bacteria from Argentinian Patagonia

“…Pseudomonas alkaligenes S22 (a strain isolated from crude oil-contaminated soil) and Pseudomonas putida 852 also exhibited hydrophilic properties; however, when growing on hydrophobic carbon source, an increase in adhesion to hydrocarbon was observed [36,37]. The data obtained in this work are consistent with previous studies [37,38] confirming the hydrophobic nature of Rhodococcus cells. With respect to the surface hydrophobicity of the genera Bacillus, Thwaite et al [39] studied a range of Bacillus species to evaluate the correlation between bacterial hydrophobicity and pathogenicity.…”

“…Furthermore, microbial AA is related to the early stages of biofilm formation on supports or at liquideair interfaces (floating biofilms, referred to as pellicles) [3]; therefore, it is an important property to be studied for future removal tests. Different components of the bacterial cell wall determine its degree of hydrophobicity, which, in turn, contributes to the cell aggregation under adverse environmental conditions [38]. In this sense, the high hydrophobicity of the cell surface has been related to the aggregation of Rhodococcus cells in flocs, which controlled the interfacial alkane entry mechanisms [43].…”

Biotransformation of (–)-Isopulegol by Rhodococcus rhodochrous

“…(-)-Isopulegol (0.025% v/v) and/or HNTs (0.1 g/L) added to the medium did not significantly affect the size of R. rhodochrous IEGM 1362 cells (Table S1), the cell surface roughness, or electrokinetic potential (Table S2). R. rhodochrous is known for its resistance to metal nanoparticles [31]. A slight change in roughness and zeta potential of the cell surface in the presence of nickel nanoparticles has been recorded for another strain-IEGM 1363.…”

Ethylicin Inhibition of Xanthomonas oryzae pv. oryzicola In Vitro and In Vivo

“…Studies on the effect of antibacterial materials are generally performed by scanning electron microscopy observations of bacterial morphology and structure because the attached ions increase the permeability of the cell membrane, leading to the destruction of the bacterial tegument. − The surface wrinkles on the Xoc cells increased with increasing concentrations of ethylicin administered (Figure ). The morphology of CK (without ethylicin) was unaffected.…”