Effect of physicochemical surface characteristics on bacterial attachment Institute of Chemical...

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.