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Understanding the antimicrobial mechanism of TiO₂-based nanocomposite films in a pathogenic bacterium.

Kubacka A, Diez MS, Rojo D, Bargiela R, Ciordia S, Zapico I, Albar JP, Barbas C, Martins dos Santos VA, Fernández-García M, Ferrer M - Sci Rep (2014)

Bottom Line: However, the mechanism by which these materials induce microbial death and the effects that they have on microbes are poorly understood.Rather, the photocatalytic action triggers the decreased expression of a large array of genes/proteins specific for regulatory, signalling and growth functions in parallel with subsequent selective effects on ion homeostasis, coenzyme-independent respiration and cell wall structure.The present work provides the first solid foundation for the biocidal action of titania and may have an impact on the design of highly active photobiocidal nanomaterials.

View Article: PubMed Central - PubMed

Affiliation: Institute of Catalysis, CSIC, 28049 Madrid, Spain.

ABSTRACT
Titania (TiO₂)-based nanocomposites subjected to light excitation are remarkably effective in eliciting microbial death. However, the mechanism by which these materials induce microbial death and the effects that they have on microbes are poorly understood. Here, we assess the low dose radical-mediated TiO₂ photocatalytic action of such nanocomposites and evaluate the genome/proteome-wide expression profiles of Pseudomonas aeruginosa PAO1 cells after two minutes of intervention. The results indicate that the impact on the gene-wide flux distribution and metabolism is moderate in the analysed time span. Rather, the photocatalytic action triggers the decreased expression of a large array of genes/proteins specific for regulatory, signalling and growth functions in parallel with subsequent selective effects on ion homeostasis, coenzyme-independent respiration and cell wall structure. The present work provides the first solid foundation for the biocidal action of titania and may have an impact on the design of highly active photobiocidal nanomaterials.

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Distribution by function of genes expressed at higher (light grey colour) and lower (dark grey colour) transcript level in response to low doses of TiO2-UV treatment compared to the control (UV + EVOH) condition.The number of genes assigned to each category was calculated on the basis of the gene expression levels specifically shown in Supplementary Table S2. Abbreviation as follows: CMR, central metabolic reactions. For the cell wall biogenesis pathway, the number of under-expressed genes encoding proteins involved in lipopolysaccharide and peptidoglycan metabolisms, pilus biosynthesis and protein insertion are specifically shown (inset at the right down corner).
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f3: Distribution by function of genes expressed at higher (light grey colour) and lower (dark grey colour) transcript level in response to low doses of TiO2-UV treatment compared to the control (UV + EVOH) condition.The number of genes assigned to each category was calculated on the basis of the gene expression levels specifically shown in Supplementary Table S2. Abbreviation as follows: CMR, central metabolic reactions. For the cell wall biogenesis pathway, the number of under-expressed genes encoding proteins involved in lipopolysaccharide and peptidoglycan metabolisms, pilus biosynthesis and protein insertion are specifically shown (inset at the right down corner).

Mentions: The limited reduction in the maximum growth rate points to the fact that the main factors leading to a decreased survival rate of P. aeruginosa (when confronted to TiO2-based biocidal materials)6 are not directly caused by the loss of metabolic robustness. The differentially expressed genes identified on the arrays (Supplementary Table S2) were classified according to biological categories for interpreting the data. As shown in Fig. 3, fourteen general biological categories were defined, with the number of differentially expressed genes assigned to 11 out of 14 categories being extensively altered as a consequence of TiO2-UV treatment. Fig. 4 further summarises the average expression levels of the genes assigned to each of the corresponding biological categories.


Understanding the antimicrobial mechanism of TiO₂-based nanocomposite films in a pathogenic bacterium.

Kubacka A, Diez MS, Rojo D, Bargiela R, Ciordia S, Zapico I, Albar JP, Barbas C, Martins dos Santos VA, Fernández-García M, Ferrer M - Sci Rep (2014)

Distribution by function of genes expressed at higher (light grey colour) and lower (dark grey colour) transcript level in response to low doses of TiO2-UV treatment compared to the control (UV + EVOH) condition.The number of genes assigned to each category was calculated on the basis of the gene expression levels specifically shown in Supplementary Table S2. Abbreviation as follows: CMR, central metabolic reactions. For the cell wall biogenesis pathway, the number of under-expressed genes encoding proteins involved in lipopolysaccharide and peptidoglycan metabolisms, pilus biosynthesis and protein insertion are specifically shown (inset at the right down corner).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928576&req=5

f3: Distribution by function of genes expressed at higher (light grey colour) and lower (dark grey colour) transcript level in response to low doses of TiO2-UV treatment compared to the control (UV + EVOH) condition.The number of genes assigned to each category was calculated on the basis of the gene expression levels specifically shown in Supplementary Table S2. Abbreviation as follows: CMR, central metabolic reactions. For the cell wall biogenesis pathway, the number of under-expressed genes encoding proteins involved in lipopolysaccharide and peptidoglycan metabolisms, pilus biosynthesis and protein insertion are specifically shown (inset at the right down corner).
Mentions: The limited reduction in the maximum growth rate points to the fact that the main factors leading to a decreased survival rate of P. aeruginosa (when confronted to TiO2-based biocidal materials)6 are not directly caused by the loss of metabolic robustness. The differentially expressed genes identified on the arrays (Supplementary Table S2) were classified according to biological categories for interpreting the data. As shown in Fig. 3, fourteen general biological categories were defined, with the number of differentially expressed genes assigned to 11 out of 14 categories being extensively altered as a consequence of TiO2-UV treatment. Fig. 4 further summarises the average expression levels of the genes assigned to each of the corresponding biological categories.

Bottom Line: However, the mechanism by which these materials induce microbial death and the effects that they have on microbes are poorly understood.Rather, the photocatalytic action triggers the decreased expression of a large array of genes/proteins specific for regulatory, signalling and growth functions in parallel with subsequent selective effects on ion homeostasis, coenzyme-independent respiration and cell wall structure.The present work provides the first solid foundation for the biocidal action of titania and may have an impact on the design of highly active photobiocidal nanomaterials.

View Article: PubMed Central - PubMed

Affiliation: Institute of Catalysis, CSIC, 28049 Madrid, Spain.

ABSTRACT
Titania (TiO₂)-based nanocomposites subjected to light excitation are remarkably effective in eliciting microbial death. However, the mechanism by which these materials induce microbial death and the effects that they have on microbes are poorly understood. Here, we assess the low dose radical-mediated TiO₂ photocatalytic action of such nanocomposites and evaluate the genome/proteome-wide expression profiles of Pseudomonas aeruginosa PAO1 cells after two minutes of intervention. The results indicate that the impact on the gene-wide flux distribution and metabolism is moderate in the analysed time span. Rather, the photocatalytic action triggers the decreased expression of a large array of genes/proteins specific for regulatory, signalling and growth functions in parallel with subsequent selective effects on ion homeostasis, coenzyme-independent respiration and cell wall structure. The present work provides the first solid foundation for the biocidal action of titania and may have an impact on the design of highly active photobiocidal nanomaterials.

Show MeSH
Related in: MedlinePlus