Effect of physicochemical surface characteristics on bacterial attachment

1. Institute of Chemical Technology Prague Department of Food Preservation and Meat Technology Effect of physicochemical surface characteristics on bacterial attachment Petra Sedláčková

2. Bacterial adhesion x Biofilm formation • effect of surface characteristic • microorganism used for attachment – widely described in nature, isolated infood processing environments

3. Microorganisms • Pseudomonas fluorescens (DBM 3113 BHA) • gram-negative, aerobic bacterium, cat.+, ox.+ scanning electron micrographs of Pseudomonas biofilm formation

4. Escherichia coli (DBM 3125 BHA) • gram-negative, cat.+, ox.- scanning electron micrograph of E. coli biofilm formation

5. Asaia bogorensis • gram-negative, aerobic bacterium, cat.+, ox.- scanning electron micrographs of A. bogorensis biofilm formation

6. Tested surfaces • stainless steel – AIS 304 • 40 x 40 mm, tested area13 x 13 mm • the slides were washed in sanitizers solution, rinsed by distilled water and autoclaved at 121 °C for 20 min

7. glass – for the microbial purpose • 76 x 26 mm, tested area 13 x 13 mm • the slides were washed for 30 min in sanitizers solution, rinsed by distilled water , were placed on aluminium foil, covered and autoclaved at 121 °Cfor 20 min

8. incubation (3,6,12,24 hr) 100 μl rinsing by sterile nutrient broth + addition nutrient broth incubation (24 hr) 100 μl evaluation

9. bacteria were scraped from test surfaceswith a cotton-wool swab transferred into test tube containing 10 ml physiological solution stirred for 1 min to release the cells into the solution agar agar Cultivation on agar: P. fluorescens: 25 °C, 24 hr, A. bogorensis 25 °C, 48 hr, E. coli 37 °C, 24 hr

10. Attachment of P. fluorescens, A. bogorensis, E. coli on stainless steel and glass Detection limit 2,9 * 10 -1 CFU * cm -3

11. a) 3, 6 ,12 ,24 attachment of Asaia bogorensis b) 3, 6 ,12 ,24 attachment of Pseudomonas fluorescens detection limit 2,9 * 10 -1 CFU * cm -3 c) 3, 6 ,12 ,24 attachment of Escherichia coli

12. attachment of all tested microorganisms on stainless steel x glass Detection limit 2,9 * 10 -1 CFU * cm -3

13. Conclusion • P. fluorescens at 3 hr incubation had higher attachment values compared to other tested microorganisms. • Cell numbers for 24 hr biofilms are significantly different between P. fluorescens and Escherichia coli. • No significant effect of initial attachment on biofilm growthfor P. fluorescens and A. bogorensis between stainless steel and glass was found.