The impact of metabolic state on Cd adsorption onto bacterial cells

Abstract

This study examines the effect of bacterial metabolism on the adsorption of Cd onto Gram‐positive and Gram‐negative bacterial cells. Metabolically active Gram‐positive cells adsorbed significantly less Cd than non‐metabolizing cells. Gram‐negative cells, however, showed no systematic difference in Cd adsorption between metabolizing and non‐metabolizing cells. The effect of metabolism on Cd adsorption to Gram‐positive cells was likely due to an influx of protons in and around the cell wall from the metabolic proton motive force, promoting competition between Cd and protons for adsorption sites on the cell wall. The relative lack of a metabolic effect on Cd adsorption onto Gram‐negative compared to Gram‐positive cells suggests that Cd binding in Gram‐negative cells is focused in a region of the cell wall that is not reached, or is unaffected by this proton flux. Thermodynamic modeling was used to estimate that proton pumping causes the pH in the cell wall of metabolizing Gram‐positive bacteria to decrease from the bulk solution value of 7.0 to approximately 5.7.

Surface charge and zeta-potential of metabolically active and dead cyanobacteria

“…Sodium azide acts as a bacteriostatic agent inhibiting protein production, DNA replication, and cellular metabolism. Accordingly, this agent uncouples the proton pump and depletes the cell wall of H + [2,26,27]. Dead cell suspensions were prepared by autoclaving an aliquot of living cyanobacteria stock at 121 • C for 20 min.…”

Effect of the heterotrophic bacterium Pseudomonas reactans on olivine dissolution kinetics and implications for CO2 storage in basalts

“…Inactivated cells were produced using 0.01 M sodium azide (NaN 3 ) for the full duration of experiments. The use of NaN 3 as metabolic inhibitor for heterotrophic bacteria is well established (i.e., Urrutia Mera et al, 1992;Johnson et al, 2007). Another stock of dead cells was prepared via treating suspension of live bacteria in 4% glutaraldehyde solution during 4 h.…”

Do photosynthetic bacteria have a protective mechanism against carbonate precipitation at their surfaces?

“…Additional viability tests including variable staining, and O 2 respiration measurements (c.f. Johnson et al, 2007) were not performed. The remaining 5 mL were filtered through a 0.22 lm filter to remove biomass from the suspension.…”