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.