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Photodynamic antimicrobial chemotherapy in aquaculture: photoinactivation studies of Vibrio fischeri.

Alves E, Faustino MA, Tomé JP, Neves MG, Tomé AC, Cavaleiro JA, Cunha Â, Gomes NC, Almeida A - PLoS ONE (2011)

Bottom Line: The variations in pH (6.5-8.5), temperature (10-25°C), salinity (20-40 g L(-1)) and oxygen concentration did not significantly affect the PI of V. fischeri, once in all tested conditions the bioluminescent signal decreased to the detection limit of the method (≈7 log reduction).The assays using aquaculture water showed that the efficiency of the process is affected by the suspended matter.Total PI of V. fischeri in aquaculture water was achieved under solar light in the presence of 20 µM of Tri-Py(+)-Me-PF.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal.

ABSTRACT

Background: Photodynamic antimicrobial chemotherapy (PACT) combines light, a light-absorbing molecule that initiates a photochemical or photophysical reaction, and oxygen. The combined action of these three components originates reactive oxygen species that lead to microorganisms' destruction. The aim was to evaluate the efficiency of PACT on Vibrio fischeri: 1) with buffer solution, varying temperature, pH, salinity and oxygen concentration values; 2) with aquaculture water, to reproduce photoinactivation (PI) conditions in situ.

Methodology/principal findings: To monitor the PI kinetics, the bioluminescence of V. fischeri was measured during the experiments. A tricationic meso-substituted porphyrin (Tri-Py(+)-Me-PF) was used as photosensitizer (5 µM in the studies with buffer solution and 10-50 µM in the studies with aquaculture water); artificial white light (4 mW cm(-2)) and solar irradiation (40 mW cm(-2)) were used as light sources; and the bacterial concentration used for all experiments was ≈10(7) CFU mL(-1) (corresponding to a bioluminescence level of 10(5) relative light units--RLU). The variations in pH (6.5-8.5), temperature (10-25°C), salinity (20-40 g L(-1)) and oxygen concentration did not significantly affect the PI of V. fischeri, once in all tested conditions the bioluminescent signal decreased to the detection limit of the method (≈7 log reduction). The assays using aquaculture water showed that the efficiency of the process is affected by the suspended matter. Total PI of V. fischeri in aquaculture water was achieved under solar light in the presence of 20 µM of Tri-Py(+)-Me-PF.

Conclusions/significance: If PACT is to be used in environmental applications, the matrix containing target microbial communities should be previously characterized in order to establish an efficient protocol having into account the photosensitizer concentration, the light source and the total light dose delivered. The possibility of using solar light in PACT to treat aquaculture water makes this technology cost-effective and attractive.

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Photoinactivation of V. fischeri with Tri-Py+-Me-PF at 10, 20 and 50 µM, in an aquaculture water sample collected in June 2010, under 4 mW cm−2 irradiation.A: Assays with non-filtered water portion; B: Assays with water filtered by 0.7 µm membrane; C: Assays with water filtered by 0.2 µm membrane. Values represent the mean of two replicates of the same sample; error bars indicate the standard deviation.
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pone-0020970-g007: Photoinactivation of V. fischeri with Tri-Py+-Me-PF at 10, 20 and 50 µM, in an aquaculture water sample collected in June 2010, under 4 mW cm−2 irradiation.A: Assays with non-filtered water portion; B: Assays with water filtered by 0.7 µm membrane; C: Assays with water filtered by 0.2 µm membrane. Values represent the mean of two replicates of the same sample; error bars indicate the standard deviation.

Mentions: For all the water matrices used (non-filtered and filtered), light controls showed that the light emission from bacteria was not affected by the suspended solids present in the water. Dark controls showed that the concentration of 50 µM of PS was not toxic for this bacterium, once the bioluminescence values were not affected during all these experiments (Figure 6 and Figure 7).


Photodynamic antimicrobial chemotherapy in aquaculture: photoinactivation studies of Vibrio fischeri.

Alves E, Faustino MA, Tomé JP, Neves MG, Tomé AC, Cavaleiro JA, Cunha Â, Gomes NC, Almeida A - PLoS ONE (2011)

Photoinactivation of V. fischeri with Tri-Py+-Me-PF at 10, 20 and 50 µM, in an aquaculture water sample collected in June 2010, under 4 mW cm−2 irradiation.A: Assays with non-filtered water portion; B: Assays with water filtered by 0.7 µm membrane; C: Assays with water filtered by 0.2 µm membrane. Values represent the mean of two replicates of the same sample; error bars indicate the standard deviation.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3117864&req=5

pone-0020970-g007: Photoinactivation of V. fischeri with Tri-Py+-Me-PF at 10, 20 and 50 µM, in an aquaculture water sample collected in June 2010, under 4 mW cm−2 irradiation.A: Assays with non-filtered water portion; B: Assays with water filtered by 0.7 µm membrane; C: Assays with water filtered by 0.2 µm membrane. Values represent the mean of two replicates of the same sample; error bars indicate the standard deviation.
Mentions: For all the water matrices used (non-filtered and filtered), light controls showed that the light emission from bacteria was not affected by the suspended solids present in the water. Dark controls showed that the concentration of 50 µM of PS was not toxic for this bacterium, once the bioluminescence values were not affected during all these experiments (Figure 6 and Figure 7).

Bottom Line: The variations in pH (6.5-8.5), temperature (10-25°C), salinity (20-40 g L(-1)) and oxygen concentration did not significantly affect the PI of V. fischeri, once in all tested conditions the bioluminescent signal decreased to the detection limit of the method (≈7 log reduction).The assays using aquaculture water showed that the efficiency of the process is affected by the suspended matter.Total PI of V. fischeri in aquaculture water was achieved under solar light in the presence of 20 µM of Tri-Py(+)-Me-PF.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Centre for Environmental and Marine Studies, University of Aveiro, Aveiro, Portugal.

ABSTRACT

Background: Photodynamic antimicrobial chemotherapy (PACT) combines light, a light-absorbing molecule that initiates a photochemical or photophysical reaction, and oxygen. The combined action of these three components originates reactive oxygen species that lead to microorganisms' destruction. The aim was to evaluate the efficiency of PACT on Vibrio fischeri: 1) with buffer solution, varying temperature, pH, salinity and oxygen concentration values; 2) with aquaculture water, to reproduce photoinactivation (PI) conditions in situ.

Methodology/principal findings: To monitor the PI kinetics, the bioluminescence of V. fischeri was measured during the experiments. A tricationic meso-substituted porphyrin (Tri-Py(+)-Me-PF) was used as photosensitizer (5 µM in the studies with buffer solution and 10-50 µM in the studies with aquaculture water); artificial white light (4 mW cm(-2)) and solar irradiation (40 mW cm(-2)) were used as light sources; and the bacterial concentration used for all experiments was ≈10(7) CFU mL(-1) (corresponding to a bioluminescence level of 10(5) relative light units--RLU). The variations in pH (6.5-8.5), temperature (10-25°C), salinity (20-40 g L(-1)) and oxygen concentration did not significantly affect the PI of V. fischeri, once in all tested conditions the bioluminescent signal decreased to the detection limit of the method (≈7 log reduction). The assays using aquaculture water showed that the efficiency of the process is affected by the suspended matter. Total PI of V. fischeri in aquaculture water was achieved under solar light in the presence of 20 µM of Tri-Py(+)-Me-PF.

Conclusions/significance: If PACT is to be used in environmental applications, the matrix containing target microbial communities should be previously characterized in order to establish an efficient protocol having into account the photosensitizer concentration, the light source and the total light dose delivered. The possibility of using solar light in PACT to treat aquaculture water makes this technology cost-effective and attractive.

Show MeSH
Related in: MedlinePlus