The effects of low levels of trivalent ions on a standard strain of Escherichia coli (ATCC 11775) in aqueous solutions

Abstract

Considering the ever‐growing usage of trivalent salts in water treatment, for example, lanthanum salts in rare earth, AlCl3 and FeCl3, the effects of different trivalent cations on the bacterium Escherichia coli (E. coli) ATCC 11775 strain have been studied in aqueous solutions. From colony incubation studies, the colony‐forming unit (CFU) densities were found to decrease significantly in the presence of even low levels (10−5 mol/L) of lanthanum chloride. This level of reduction in CFU number is comparable to the results obtained using the known bacteriocidal cationic surfactant, C14 TAB. By comparison, exposure of the cells to low levels of trivalent ion, aluminum and chromium ion solutions produced only modest reductions in CFU density. The results from the incubation studies suggest that the bacteriostatic mechanism of La3+ ions has similarities to that of the cationic surfactant, and different to that of the other trivalent ions. Size distribution and zeta potential measurements of E. coli cells and phospholipid vesicles in the presence of trivalent cations solutions suggested significant cell shrinkage probably caused by membrane disruption.

Influence of Metal Cations on the Viscoelastic Properties of Escherichia coli Biofilms

“…Thus, if these ions caused aggregation, the formed aggregates are still small. 55 Here, the metal ion concentrations in the biofilms were much higher (20 mM), and cell aggregation induced by trivalent cations may occur in the biofilms. However, this effect would occur equally for all matrix compositions so that differences between strains must originate from other factors than ion-induced cell aggregation.…”

“…For planktonic E. coli cells, it was shown that Fe­(III) and Al­(III) in a concentration of 0.01 mM reduce the number of colony forming units by 50% . While it appears likely that biofilms provide protection against heavy metal toxicity, as demonstrated for P.…”

“…For planktonic E. coli cells, it was shown that Fe(III) and Al(III) in a concentration of 0.01 mM reduce the number of colony forming units by 50%. 55 While it appears likely that biofilms provide protection against heavy metal toxicity, as demonstrated for P. aeruginosa , 56 it cannot be fully neglected that these cations also have an effect on E. coli cells in biofilms. It is reasonable to assume, however, that the viscoelastic biofilm properties are not significantly altered by the appearance of non-viable bacteria as bacterial cells can most likely be considered as particles in a composite material.…”

The role of divalent iron cations in the growth, adhesive properties and extracellular adaptation mechanisms of Propionibacterium sp

“…The cell agglomerates forming can be explained by the medium's protective response to the metal excess. Also, according to the literature, the presence of di- and trivalent cations reduce electrostatic repulsion, promoting adhesion due to charged layers' shrinkage on the surface ( Deng et al, 2018 ). Results suggest that exometabolite synthesis supports the adaptation of PAB to iron ions ( Inami et al, 2017 ).…”

Influence of metal cations on the viscoelastic properties of Escherichia coli biofilms

“…For planktonic E. coli cells, it was shown that Fe(III) and Al(III) in a concentration of 0.01 mM reduce the number of colony forming units by 50 %. 51 While it appears likely that biofilms provide protection against heavy metal toxicity, as demonstrated for P. aeruginosa , 52 it cannot be fully neglected that these cations also have an effect on E. coli cells in biofilms. It is reasonable to assume, however, that the viscoelastic biofilm properties are not significantly altered by the appearance of non-viable bacteria as bacterial cells can most likely be considered as particles in a composite material.…”