effect of physicochemical surface characteristics on bacterial attachment institute of chemical...
TRANSCRIPT
Effect of physicochemical surface characteristics on
bacterial attachment
Institute of Chemical Technology PragueDepartment of Food Preservation and Meat Technology
Petra Sedláčková
Bacterial adhesion x Biofilm formation
effect of surface characteristic
microorganism used for attachment – widely described in nature, isolated in food processing environments
Microorganisms
Pseudomonas fluorescens (DBM 3113 BHA)
• gram-negative, aerobic bacterium, cat.+, ox.+
scanning electron micrographs of Pseudomonas biofilm formation
Escherichia coli (DBM 3125 BHA)
• gram-negative, cat.+, ox.-
scanning electron micrograph of E. coli biofilm formation
Asaia bogorensis• gram-negative, aerobic bacterium, cat.+, ox.-
scanning electron micrographs of A. bogorensis biofilm formation
Tested surfaces
stainless steel – AIS 30440 x 40 mm, tested area 13 x 13 mm
the slides were washed in sanitizers solution, rinsed by distilled water and autoclaved at 121 °C for 20 min
glass – for the microbial purpose76 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 °C for 20 min
100 μl
incubation (3,6,12,24 hr)
rinsing by sterile nutrient broth + addition nutrient broth
100 μl
incubation (24 hr)
evaluation
agar agar
bacteria were scraped from test surfaces with a cotton-wool swab
transferred into test tube containing 10 ml physiological solution
stirred for 1 min to release the cells into the solution
Cultivation on agar:
P. fluorescens: 25 °C, 24 hr, A. bogorensis 25 °C, 48 hr, E. coli 37 °C, 24 hr
0
1
2
3
4
5
6
0 5 10 15 20 25
time [hr]
log
CFU
*cm
-3
A. bogorensis - st. steel E. coli - st. steel
P. fl uorescens - st. steel A. bogorensis - glassE. coli - glass P. fl uorescens - glass
Attachment of P. fluorescens, A. bogorensis, E. coli on stainless steel and glassDetection limit 2,9 * 10 -1 CFU * cm -2
0
1
2
3
4
5
0 5 10 15 20 25 30
time [hr]
log
CFU
*cm-
3
A. bogorensis - st. steel A. bogorensis - glass
0
1
2
3
4
5
6
0 5 10 15 20 25 30
time [hr]
log C
FU
*cm-
3
P. fl uorescens - st. steel P. fl uorescens - glass
0
1
2
3
4
0 5 10 15 20 25 30
time [hr]
log
CFU
*cm
-3
E. coli - st. steel E. coli - glass
detection limit 2,9 * 10 -1 CFU * cm -2
a) 3, 6 ,12 ,24 attachment of Asaia bogorensis
b) 3, 6 ,12 ,24 attachment of Pseudomonas fluorescens
c) 3, 6 ,12 ,24 attachment of Escherichia coli
0
1
2
3
4
5
6
0 5 10 15 20 25 30
time [hr]
log
CFU
*cm
-3
A. bogorensis - glass E. coli - glass P. fl uorescens - glass
0
1
2
3
4
5
6
0 5 10 15 20 25 30
time [hr]
log
CFU
*cm
-3
A. bogorensis - st. steel E. coli - st. steel P. fl uorescens - st. steel
Detection limit 2,9 * 10 -1 CFU * cm -2
attachment of all tested microorganisms on stainless steel x glass
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 growth (for each microorganism) between stainless steel and glass was found.