Research Article | Therapeutics and Prevention

Broad-Spectrum Antimicrobial and Antibiofilm Activity of a Natural Clay Mineral from British Columbia, Canada

Shekooh Behroozian, Sarah L. Svensson, Loretta Y. Li, Julian E. Davies
Pascale F. Cossart, Editor
DOI: 10.1128/mBio.02350-20

Article Figures & Data

Figures

  • FIG 1
    FIG 1

    (A to C) Viability of E. coli MG1655 (A), S. aureus RN4220 (B), and P. aeruginosa PAO1 (C) after treatment with 1% (wt/vol) aqueous suspensions of KC. (D) Growth inhibition activity of 25% (wt/vol) KC against M. marinum strain M in 7H9 broth. The dotted line at log10 = 1 of the y axis represents the limit of detection for CFU. The carets (^) indicate that the levels of viable cells were below the limit of detection at the indicated time point. Error bars represent standard errors (SE) of the means of results from at least three independent replicates.

  • FIG 2
    FIG 2

    Viability of fungal strains C. albicans SC5314 (left) and C. neoformans H99 (right) after treatment with 1% (wt/vol) (A) or 5% (wt/vol) (B) aqueous suspensions of KC at 30°C. The dotted line at log10 = 1 represents the limit of detection. The carets (^) indicate that the levels of viable cells were below the limit of detection at the indicated time point. Error bars represent standard errors (SE) of the means of results from at least three independent replicates.

  • FIG 3
    FIG 3

    Antibacterial activity of KC aqueous leachates L50, L100, and L500 against E. coli MG1655 (A), S. aureus RN4220 (B), and P. aeruginosa PAO1 (C) compared to low-pH phosphate buffers. The dotted line at log10 = 1 of the y axis represents the limit of detection for CFU. Error bars represent standard errors (SE) of the means of results from at least three independent replicates. The key is shared by all three panels. The pH of each solution is shown in parentheses.

  • FIG 4
    FIG 4

    Effect of pH on antibacterial activity of KC aqueous leachates. From L50 (pH 3.8), a sample of leachate with pH altered to 7.0 was prepared. Levels of viability of E. coli MG1655 treated with these leachates or with 100 mM phosphate buffer at equal pH were compared. The dotted line at log10 = 1 of the y axis represents the limit of detection for CFU. Error bars represent standard errors (SE) of the means of results from at least three independent replicates. The pH of each solution is shown in parentheses.

  • FIG 5
    FIG 5

    Viability of E. coli MG1655 in 1% (wt/vol) aqueous suspension of KC treated with EDTA (A) and of KC aqueous leachate (KC-L) with EDTA and pH adjustment (B). The dotted line at log10 = 1 of the y axis represents the limit of detection for CFU. Error bars represent standard errors (SE) of the means of results from at least three independent replicates. The pH of each solution is shown in parentheses.

  • FIG 6
    FIG 6

    Viability of E. coli MG1655 in 1% (wt/vol) aqueous suspension of KC prewashed with 2,2′-bipyridyl (BPY) (A) or 10 mM deferoxamine (DFO) (C) and of KC leachate (KC-L) treated with BPY and pH adjustment (B) or 1 mM DFO (D). The dotted line at log10 = 1 of the y axis represents the limit of detection for CFU. Error bars represent standard errors (SE) of the means of results from at least three independent replicates. The pH of each solution is shown in parentheses.

  • FIG 7
    FIG 7

    Effect of KC leachates on biofilm formation and growth (left) and survival of preformed biofilm (right) in crystal violet assays of P. aeruginosa PAO1 (A) and S. aureus RN4220 (B). Error bars represent standard errors (SE) of the means of results from at least three independent replicates. The pH of each solution is shown in parentheses.

Tables

  • TABLE 1

    pH of KC aqueous suspensions and leachates treated with EDTA, BPY, or DFOa

    TABLE 1

    • ↵a BPY, 2,2′-bipyridyl; DFO, deferoxamine.

Supplemental Material

Back to top
Download PDF
Citation Tools
Print

Alerts
Email

KEYWORDS

antibacterial agent
clay mineral
antimicrobial clay
bacterial biofilm
fungal pathogen

Related Articles

Cited By...