Ni(II) Interactions in Boreal Paenibacillus sp., Methylobacterium sp., Paraburkholderia sp., and Pseudomonas sp. Strains Isolated From an Acidic, Ombrotrophic Bog

Abstract

The uptake of nickel [Ni(II)] by Paenibacillus sp., Methylobacterium sp., Paraburkholderia sp., and Pseudomonas sp. strains isolated from a boreal bog was studied using batch experiments. All strains removed Ni(II) from the solution and the uptake efficiency was affected by the nutrient source, incubation temperature, time, and pH. As highest Ni uptake (with a maximum Kd of 1890 L/kg DW) was recorded for the Pseudomonas sp. strains, these bacteria were used in the following protein expression (SDS-PAGE and MALDI-TOFF), transmission electron microscopy (TEM) and EDS experiments. In addition, Freundlich and Langmuir sorption isotherms were determined. In the Ni(II) treated cells, dense crystalline intra-cellular accumulations were observed in TEM examinations, which were identified as Ni accumulations using EDS. SDS-PAGE and MALDI-TOFF spectra of Ni(II) treated cells showed several changes in the protein profiles, which can indicate active accumulation of Ni in these bacteria. Concurrently, we observed Ni(II) uptake to follow Freundlich and Langmuir isotherms, suggesting straight cellular biosorption in addition to the intra-cellular accumulation. The role of cellular (cell membrane and cell wall) functional groups involved in Ni(II) binding were therefore studied using Fourier transformation infrared spectroscopy. These analyses supported the potential role of the alcoholic hydroxyl, carboxyl and amine groups in Ni(II) binding in these bacteria, therefore suggesting two different Ni(II) uptake mechanisms; (i) intra-cellular accumulation [possibly connected to detoxification of Ni(II)], and (ii) straight biosorption on cell membrane/wall functional groups.

Microbial Community Composition Correlates with Metal Sorption in an Ombrotrophic Boreal Bog: Implications for Radionuclide Retention

“…Commercially available peat has successfully been used as sorbent for the removal of Ni from aqueous solutions [125], indicating that the peat itself may sorb the Ni and perhaps that is why there is a specific layer where the Ni appears to be enriched in the peat profile. Nevertheless, bacterial strains originating from Lastensuo have been shown to accumulate Ni intracellularly as well as by sorption to cell surfaces [23].…”

“…Retardation may occur through cell surface metal-binding functional groups, like carboxyl, hydroxyl, phosphate, and sulfate groups [18][19][20]. In addition, many microbes are able to accumulate Ni also inside the cells (see, e.g., in [22]) and until this date at least two different uptake mechanisms have been reported: ATP-binding cassette (ABCtype) transporters as well as Ni-specific permeases [23]. The possible toxic effects of Ni may be suppressed during active accumulation inside bacterial cells through detoxification reactions and previously we observed that Ni(II) concentrations between 0.01 and 1 mM had no toxic effects on Pseudomonas sp.…”

Impact of Tellurite on the Metabolism of Paenibacillus pabuli AL109b With Flagellin Production Explaining High Reduction Capacity

“…for its potential in biotechnological applications ( Jimoh and Lin, 2019 ; Du et al, 2021 ). To this date, some studies on the interactions of Paenibacillus strains with metals have been produced ( Knuutinen et al, 2019 ; Ogunyemi et al, 2020 ) but only a few concerning Te ( Chien and Han, 2009 ). Strains of Paenibacillus have been characterized for their biochemistry and proteomics and considered of interest in rhizostabilization of cadmium ( Kumari and Thakur, 2018 ) for their high metal resistance, siderophore production, biocontrol activities, and xenobiotic degradation.…”