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Opening Study on the Development of a New Biosensor for Metal Toxicity Based on Pseudomonas fluorescens Pyoverdine.

Chiadò A, Varani L, Bosco F, Marmo L - Biosensors (Basel) (2013)

Bottom Line: To date, different kinds of biosensing elements have been used effectively for environmental monitoring.Each of these variables has been shown to influence the synthesis of siderophore: for instance, the lower the temperature, the higher the production of pyoverdine.Moreover, the concentration of pyoverdine produced in the presence of metals has been compared with the maximum allowable concentrations indicated in international regulations (e.g., 98/83/EC), and a correlation that could be useful to build a colorimetric biosensor has been observed.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129, Torino, Italy. alessandro.chiado@polito.it.

ABSTRACT
To date, different kinds of biosensing elements have been used effectively for environmental monitoring. Microbial cells seem to be well-suited for this task: they are cheap, adaptable to variable field conditions and give a measurable response to a broad number of chemicals. Among different pollutants, heavy metals are still a major problem for the environment. A reasonable starting point for the selection of a biorecognition element to develop a biosensor for metals could be that of a microorganism that exhibits good mechanisms to cope with metals. Pseudomonads are characterized by the secretion of siderophores (e.g., pyoverdine), low-molecular weight compounds that chelate Fe3+ during iron starvation. Pyoverdine is easily detected by colorimetric assay, and it is suitable for simple online measurements. In this work, in order to evaluate pyoverdine as a biorecognition element for metal detection, the influence of metal ions (Fe3+, Cu2+, Zn2+), but also of temperature, pH and nutrients, on microbial growth and pyoverdine regulation has been studied in P. fluorescens. Each of these variables has been shown to influence the synthesis of siderophore: for instance, the lower the temperature, the higher the production of pyoverdine. Moreover, the concentration of pyoverdine produced in the presence of metals has been compared with the maximum allowable concentrations indicated in international regulations (e.g., 98/83/EC), and a correlation that could be useful to build a colorimetric biosensor has been observed.

No MeSH data available.


Related in: MedlinePlus

Pyoverdine (OD400) at 24 hours in 96-well plates cultures treated with low Zn2+ concentrations.
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biosensors-03-00385-f008: Pyoverdine (OD400) at 24 hours in 96-well plates cultures treated with low Zn2+ concentrations.

Mentions: The subsequent tests, carried out in the M78 medium with a lower range of metal concentration and with different inoculum percentages, showed that the susceptibility of the microorganism for Fe3+ and Cu2+ depends not only on the concentration of metal, but also on the inoculum percentage: the lower the biomass in the inoculum, the lower the MIC. On the other hand, the microorganism grew for each zinc concentration, and after 24 h, the pyoverdine content was directly proportional to the concentration of Zn2+ in the 7.6–46 µM range (Figure 8). The reasons for this effect are not clear. One hypothesis is that the siderophore content secreted by the microorganism from zero to 7.6 μM of Zn2+ is sufficient to sustain growth, without any toxic effect. At 7.6 μM, Zn2+ became toxic to the microorganism, which increased its pyoverdine production as a protective mechanism. It is known that pyoverdine is effective in shielding the microbial cell of related Pseudomonads from Cu2+ and Zn2+ toxicity [10,15]. Unfortunately, in this work this effect was only observed for zinc and not for copper; further investigations are required to have a clearer picture of the interactions between P. fluorescens and these different metal ions.


Opening Study on the Development of a New Biosensor for Metal Toxicity Based on Pseudomonas fluorescens Pyoverdine.

Chiadò A, Varani L, Bosco F, Marmo L - Biosensors (Basel) (2013)

Pyoverdine (OD400) at 24 hours in 96-well plates cultures treated with low Zn2+ concentrations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263567&req=5

biosensors-03-00385-f008: Pyoverdine (OD400) at 24 hours in 96-well plates cultures treated with low Zn2+ concentrations.
Mentions: The subsequent tests, carried out in the M78 medium with a lower range of metal concentration and with different inoculum percentages, showed that the susceptibility of the microorganism for Fe3+ and Cu2+ depends not only on the concentration of metal, but also on the inoculum percentage: the lower the biomass in the inoculum, the lower the MIC. On the other hand, the microorganism grew for each zinc concentration, and after 24 h, the pyoverdine content was directly proportional to the concentration of Zn2+ in the 7.6–46 µM range (Figure 8). The reasons for this effect are not clear. One hypothesis is that the siderophore content secreted by the microorganism from zero to 7.6 μM of Zn2+ is sufficient to sustain growth, without any toxic effect. At 7.6 μM, Zn2+ became toxic to the microorganism, which increased its pyoverdine production as a protective mechanism. It is known that pyoverdine is effective in shielding the microbial cell of related Pseudomonads from Cu2+ and Zn2+ toxicity [10,15]. Unfortunately, in this work this effect was only observed for zinc and not for copper; further investigations are required to have a clearer picture of the interactions between P. fluorescens and these different metal ions.

Bottom Line: To date, different kinds of biosensing elements have been used effectively for environmental monitoring.Each of these variables has been shown to influence the synthesis of siderophore: for instance, the lower the temperature, the higher the production of pyoverdine.Moreover, the concentration of pyoverdine produced in the presence of metals has been compared with the maximum allowable concentrations indicated in international regulations (e.g., 98/83/EC), and a correlation that could be useful to build a colorimetric biosensor has been observed.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129, Torino, Italy. alessandro.chiado@polito.it.

ABSTRACT
To date, different kinds of biosensing elements have been used effectively for environmental monitoring. Microbial cells seem to be well-suited for this task: they are cheap, adaptable to variable field conditions and give a measurable response to a broad number of chemicals. Among different pollutants, heavy metals are still a major problem for the environment. A reasonable starting point for the selection of a biorecognition element to develop a biosensor for metals could be that of a microorganism that exhibits good mechanisms to cope with metals. Pseudomonads are characterized by the secretion of siderophores (e.g., pyoverdine), low-molecular weight compounds that chelate Fe3+ during iron starvation. Pyoverdine is easily detected by colorimetric assay, and it is suitable for simple online measurements. In this work, in order to evaluate pyoverdine as a biorecognition element for metal detection, the influence of metal ions (Fe3+, Cu2+, Zn2+), but also of temperature, pH and nutrients, on microbial growth and pyoverdine regulation has been studied in P. fluorescens. Each of these variables has been shown to influence the synthesis of siderophore: for instance, the lower the temperature, the higher the production of pyoverdine. Moreover, the concentration of pyoverdine produced in the presence of metals has been compared with the maximum allowable concentrations indicated in international regulations (e.g., 98/83/EC), and a correlation that could be useful to build a colorimetric biosensor has been observed.

No MeSH data available.


Related in: MedlinePlus