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Antimicrobial activities of commercial nanoparticles against an environmental soil microbe, Pseudomonas putida KT2440.

Gajjar P, Pettee B, Britt DW, Huang W, Johnson WP, Anderson AJ - J Biol Eng (2009)

Bottom Line: We demonstrate here their antimicrobial activity against the beneficial soil microbe, Pseudomonas putida KT2440.Flow Field-Flow Fractionation (FlFFF) of an aqueous suspension of the nano-CuO and ZnO revealed a small proportion of 5 nm NP and aggregated particulates with sizes ranging between 70 nm and 300 nm; the majority portion of material was aggregated into particles larger than 300 nm in size.The "as-made" NP of Ag, CuO and ZnO have toxic effects on a beneficial soil microbe, leading to bactericidal or bacteriostatic effects depending on the NP employed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, Utah State University, Logan, Utah 84321, USA. pgajjar@aggiemail.usu.edu

ABSTRACT

Background: The release of heavy metal-containing nanoparticles (NP) into the environment may be harmful to the efficacy of beneficial microbes that function in element cycling, pollutant degradation and plant growth. Nanoparticles of Ag, CuO and ZnO are of interest as antimicrobials against pathogenic bacteria. We demonstrate here their antimicrobial activity against the beneficial soil microbe, Pseudomonas putida KT2440.

Results: Toxicity was detected in a KT2440 construct possessing a plasmid bearing the luxAB reporter genes. "As manufactured" preparations of nano- Ag, -CuO and -ZnO caused rapid dose-dependent loss of light output in the biosensor. Cell death accompanied loss in Lux activity with treatments by nano-Ag and -CuO, but with -ZnO the treatments were bacteriostatic rather than bactericidal. Bulk equivalents of these products showed no inhibitory activity, indicating that particle size was determinant in activity. Flow Field-Flow Fractionation (FlFFF) of an aqueous suspension of the nano-CuO and ZnO revealed a small proportion of 5 nm NP and aggregated particulates with sizes ranging between 70 nm and 300 nm; the majority portion of material was aggregated into particles larger than 300 nm in size. Thus within the commercial preparation there may be microbially active and inactive forms.

Conclusion: The "as-made" NP of Ag, CuO and ZnO have toxic effects on a beneficial soil microbe, leading to bactericidal or bacteriostatic effects depending on the NP employed. The lack of toxicity from bulk materials suggests that aggregation of the NP into larger particles, possibly by factors present in the environment may reduce their nontarget antimicrobial activity.

No MeSH data available.


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Response of the P putida KT2440 biosensor to nano-CuO (A), bulk CuO (B) and Cu ions (C) at defined doses of mg Cu/L. Changes in Lux output (Relative light units RLU) and cell culturability (colony forming units Cfu) are shown. Studies were performed as described in Methods. NCD = No culturable cells detected. Data are from one study typical of at least three generated under the same conditions. Means and standard errors are shown.
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Figure 2: Response of the P putida KT2440 biosensor to nano-CuO (A), bulk CuO (B) and Cu ions (C) at defined doses of mg Cu/L. Changes in Lux output (Relative light units RLU) and cell culturability (colony forming units Cfu) are shown. Studies were performed as described in Methods. NCD = No culturable cells detected. Data are from one study typical of at least three generated under the same conditions. Means and standard errors are shown.

Mentions: The biosensor also showed loss in Lux activity when treated with nano-CuO and Cu ions but not with bulk CuO. Fig. 2A demonstrates that treatment with 10 mg Cu/L from the nano-CuO caused a time-dependent loss in light output whereas bulk CuO was inactive (Fig. 2B). Treatment with 1.0 and 0.1 mg Cu/L nano-CuO caused no effect (Fig. 2A). Ten mg Cu/L nano-CuO rapidly reduced RLU, and a toxicity threshold showing rapid RLU reduction was observed between 5 mg and 7 mg Cu/L (data not shown). Toxicity of the Cu ion, from CuCl2, towards the biosensor was apparent at 1.0 mg Cu/L with 0.1 mg/L having little effect (Fig. 2C). A rapid RLU reduction was observed for 0.5 mg/L (data not shown). Thus, nano-CuO was about ten-fold less active than the free ions for the biosensor response. To confirm that toxicity with the Cu2+ was due to the metal ions rather than the Cl-, the biosensor was exposed to Cl- from NaCl. At a dose level where Cl- was at the same concentration as that from CuCl2 when Cu was present at 10 mg/L there was no observed toxicity (data not shown).


Antimicrobial activities of commercial nanoparticles against an environmental soil microbe, Pseudomonas putida KT2440.

Gajjar P, Pettee B, Britt DW, Huang W, Johnson WP, Anderson AJ - J Biol Eng (2009)

Response of the P putida KT2440 biosensor to nano-CuO (A), bulk CuO (B) and Cu ions (C) at defined doses of mg Cu/L. Changes in Lux output (Relative light units RLU) and cell culturability (colony forming units Cfu) are shown. Studies were performed as described in Methods. NCD = No culturable cells detected. Data are from one study typical of at least three generated under the same conditions. Means and standard errors are shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2714038&req=5

Figure 2: Response of the P putida KT2440 biosensor to nano-CuO (A), bulk CuO (B) and Cu ions (C) at defined doses of mg Cu/L. Changes in Lux output (Relative light units RLU) and cell culturability (colony forming units Cfu) are shown. Studies were performed as described in Methods. NCD = No culturable cells detected. Data are from one study typical of at least three generated under the same conditions. Means and standard errors are shown.
Mentions: The biosensor also showed loss in Lux activity when treated with nano-CuO and Cu ions but not with bulk CuO. Fig. 2A demonstrates that treatment with 10 mg Cu/L from the nano-CuO caused a time-dependent loss in light output whereas bulk CuO was inactive (Fig. 2B). Treatment with 1.0 and 0.1 mg Cu/L nano-CuO caused no effect (Fig. 2A). Ten mg Cu/L nano-CuO rapidly reduced RLU, and a toxicity threshold showing rapid RLU reduction was observed between 5 mg and 7 mg Cu/L (data not shown). Toxicity of the Cu ion, from CuCl2, towards the biosensor was apparent at 1.0 mg Cu/L with 0.1 mg/L having little effect (Fig. 2C). A rapid RLU reduction was observed for 0.5 mg/L (data not shown). Thus, nano-CuO was about ten-fold less active than the free ions for the biosensor response. To confirm that toxicity with the Cu2+ was due to the metal ions rather than the Cl-, the biosensor was exposed to Cl- from NaCl. At a dose level where Cl- was at the same concentration as that from CuCl2 when Cu was present at 10 mg/L there was no observed toxicity (data not shown).

Bottom Line: We demonstrate here their antimicrobial activity against the beneficial soil microbe, Pseudomonas putida KT2440.Flow Field-Flow Fractionation (FlFFF) of an aqueous suspension of the nano-CuO and ZnO revealed a small proportion of 5 nm NP and aggregated particulates with sizes ranging between 70 nm and 300 nm; the majority portion of material was aggregated into particles larger than 300 nm in size.The "as-made" NP of Ag, CuO and ZnO have toxic effects on a beneficial soil microbe, leading to bactericidal or bacteriostatic effects depending on the NP employed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology, Utah State University, Logan, Utah 84321, USA. pgajjar@aggiemail.usu.edu

ABSTRACT

Background: The release of heavy metal-containing nanoparticles (NP) into the environment may be harmful to the efficacy of beneficial microbes that function in element cycling, pollutant degradation and plant growth. Nanoparticles of Ag, CuO and ZnO are of interest as antimicrobials against pathogenic bacteria. We demonstrate here their antimicrobial activity against the beneficial soil microbe, Pseudomonas putida KT2440.

Results: Toxicity was detected in a KT2440 construct possessing a plasmid bearing the luxAB reporter genes. "As manufactured" preparations of nano- Ag, -CuO and -ZnO caused rapid dose-dependent loss of light output in the biosensor. Cell death accompanied loss in Lux activity with treatments by nano-Ag and -CuO, but with -ZnO the treatments were bacteriostatic rather than bactericidal. Bulk equivalents of these products showed no inhibitory activity, indicating that particle size was determinant in activity. Flow Field-Flow Fractionation (FlFFF) of an aqueous suspension of the nano-CuO and ZnO revealed a small proportion of 5 nm NP and aggregated particulates with sizes ranging between 70 nm and 300 nm; the majority portion of material was aggregated into particles larger than 300 nm in size. Thus within the commercial preparation there may be microbially active and inactive forms.

Conclusion: The "as-made" NP of Ag, CuO and ZnO have toxic effects on a beneficial soil microbe, leading to bactericidal or bacteriostatic effects depending on the NP employed. The lack of toxicity from bulk materials suggests that aggregation of the NP into larger particles, possibly by factors present in the environment may reduce their nontarget antimicrobial activity.

No MeSH data available.


Related in: MedlinePlus