1. ELECTROCHEMICAL DETECTION OF BIOFILMS Maria Irene Montenegro Isabel Alexandra Pinho Maria João Vieira

2. WHAT ARE BIOFILMS? THEY ARE THE RESULT OF ADHESION AND GROWTH OF MICROORGANISMS AT INTERFACES THEY ARE MICROENVIRONMENTS WHERE SEVERAL MICROBIAL REACTIONS TAKE PLACE

3. BENEFICIAL BIOFILMS DETRIMENTAL BIOFILMS DRINKING WATER PIPES HEAT EXCHANGERS THE NEED FOR A DETECTOR THE NEED FOR A DETECTOR HEALTH AREA PRODUCTION OF SPECIFIC PRODUCTS WASTE WATER TREATMENT WHAT ARE BIOFILMS?

4. Detect biofilms: easily in early stages of formation on line MAIN LINES OF WORK

5. ELECTROCHEMICAL TECHNIQUES IMPORTANT ROLE IN ANALYTICAL CHEMISTRY DETERMINATION AND QUANTIFICATION OF A LARGE NUMBER OF ORGANIC, INORGANIC AND BIOLOGICAL COMPOUNDS ALLOWING A DETECTOR TO OPERATE IN SITU

6. Voltammogram at a Platinum electrode in 1M sulfuric acid at 25ºC; continuous triangular potencial sweeps at 40 mV s -1. Q H c and Q H a correspond, respectively, to the adsorption and desorption of hydrogen, and Q O a and Q O c to the adsorption and desorption of oxygen ( reprinted from Woods, R., 1976). ELECTROCHEMICAL TECHNIQUES

7. MATERIALS AND METHODS A PLATINUM ELECTRODE A BATCH CELL A FLOW CELL

8. SCHEMATIC VIEW OF THE BATCH CELL MATERIALS AND METHODS

9. SCHEMATIC VIEW OF THE FLOW CELL MATERIALS AND METHODS

10. Pseudomonas fluorescens CULTURE MEDIUM PHOSPHATE BUFFER GLUCOSE 5g/L PEPTONE 2.5g/L YEST EXTRACT 1.25g/L

11. PRELIMINARY RESULTS Cyclic Voltammograms recorded on a batch cell at a scan rate of 250mV/s. Voltammograms were obtained: (white) in a buffered solution; (green) in a buffered solution with 5 g/L of glucose;(blue) in a buffered solution with 2.5 g/L of peptone; (light blue) in a buffered solution 1.25 g/L of yest extract; (red) in a buffered solution with 5 g/L of glucose, 2.5 g/L of peptone and 1.25 g/L of yest extract.

12. PRELIMINARY RESULTS Cyclic Voltammograms recorded on a batch cell at a scan rate of 250mV/s. Voltammograms were obtained: (white) in a buffered solution; (green) in a buffered solution with 5 g/L of glucose;(blue) in a buffered solution with 5 g/L of glucose and 2.5 g/L of peptone; (light blue) in a buffered solution with 5 g/L of glucose and 1.25 g/L of yest extract; (red) in a buffered solution with 5 g/L of glucose, 2.5 g/L of peptone and 1.25 g/L of yest extract.

13. PRELIMINARY RESULTS Cyclic Voltammograms recorded on a batch cell at a scan rate of 250mV/s. Voltammograms were obtained: (white) with a clean electrode in the culture medium; (green) immediatly after the electrode with biofilm is immersed on the culture medium.

14. PRELIMINARY RESULTS Cyclic Voltammograms recorded on a batch cell at a scan rate of 250mV/s. Voltammograms were obtained: (white) immediatly after the electrode is immersed in the buffered solution; (green) after 5 cycles;(blue) after 100 cycles.

15. PRELIMINARY RESULTS Cyclic Voltammograms recorded on a batch cell at a scan rate of 250mV/s. Voltammograms were obtained: (white) immediatly after the electrode is immersed in the culture medium; (green) after 5 cycles;(blue) after 100 cycles.

16. PRELIMINARY RESULTS Cyclic Voltammograms recorded on a batch cell at a scan rate of 250mV/s. Voltammograms were obtained: (white) with a clean electrode in the culture medium; (green) immediatly after the electrode with biofilm is immersed on the buffer solutions; (blue) with a clean electrode in the buffer solution.

17. PRELIMINARY RESULTS

19. Cyclic Voltammograms recorded on a flow cell at a scan rate of 100mV/s. Voltammograms were obtained in a buffered solution : (white) without flow; (green) with a flow rate of 4 mL/s; (blue) with a flow rate of 15.8 mL/s; (red) with a flow rate of 33.3 mL/s.

20. CONCLUSIONS THIS SEEMS TO BE A VERY PROMISSING TECHNIQUE TO DETECT BIOFILMS THERE IS FUTURE WORK TO BE DONE with microelectrodes with other cultures of microorganisms