These slides were used for my PhD defense in 2007 (files are uploaded on 21 May, 2015). Enjoy!

1. B-1
Part 2 (Chapter 3)
Growth Inhibition of Foodborne Pathogens
by Oenococcus oeni

2. B-2
Introduction
LAB are good for foodborne pathogen control:
acids, antimicrobial compounds, GRAS, no
negative impacts

3. B-3
Aims of this study
1. Screening O. oeni against foodborne pathogen
2. Characterize antimicrobial compounds
Foodborne
pathogensO. oeni

4. B-4
Cultures
vs
24 strains
O. oeni
E. coli O157:H7
L. monocytogenes
Salm. enteritidis

5. B-5
250
C
8 days
Inoculating
producers
Indicator
s
370
C
1 to 3 days
Screening

6. B-6
Medium-MLB for O. oeni
pH was adjusted to 4.5 by adding KOH
MLB with 1.5% agar
TSB with 0.75% agar
Tryptic Soy Broth (TSB) for pathogens
Pancreatic digest of casein, Enzymatic digest of soybean
meal ,sodium chloride 5 g l-1

7. B-7
CH3, Figure 3.1
Most strains of O. oeni
were capable of
inhibiting E. coli O157:H7
Results

8. B-8
CH3, Figure 3.2
Most strains of O. oeni
were capable of inhibiting
Salm. enteritidis

9. B-9
Inhibition spectrum of O. oeni against foodborne pathogens
Indicator
Producer
E. coli O157:H7 43895
Salm. enteritidis L. monocytogenes
104035
THKOe01 / / +
THKOe02 / + +
THKOe04 + + +
THKOe05 / / +
THKOe06 + + +
THKOe07 + + +
THKOe08 + + +
THKOe09 + + +
THKOe10 + + +
THKOe11 + + +
THKOe12 + + +
THKOe13 + + +
THKOe14 + + +
THKOe15 + + +
THKOe16 - / +
THKOe17 / / +
THKOe18 + + +
THKOe19 + + +
THKOe20 / + +
THKOe21 + + +
THKOe22 + + -
THKOe23 + + +
THKOe24 + + +
THKOe25 + + +
+, inhibition; -, no inhibition; /, inhibition zone was hazy
CH3, Table 3.1

10. B-10
E. coli O157:H7--> inhibited by 18 strains
Salm. enteritidis --> inhibited by 20 strains
L. monocytogenes --> inhibited by 23 strains
THKOe04, 06, 10 and 23 were selected for
characterizing antimicrobial compounds.

11. B-11
For identifying antimicrobial compounds:
Protease
Catalase
Buffer solution
Analysis of
potential compounds
Preparation of
compounds
Spot-on-lawn
method
Well
diffusion
method

12. B-12
CH3, Table 3.2 Sensitivity tests
Producer and treatment
Indicator
E. coli O157:H7 Salm. enteritidis L. monocytogenes
THKOe04 Protease Type IX - - -
Protease Type XIII - - -
Protease Type XIV - - -
Protease Type XVIII - - -
Pronase E - - -
Savinase - - -
Catalase - - -
Buffer / - -
THKOe06 Protease Type IX - - -
Protease Type XIII - - -
Protease Type XIV - - -
Protease Type XVIII - - -
Pronase E - - -
Savinase - - -
Catalase - - -
Buffer + - /
THKOe10 Protease Type IX - - -
Protease Type XIII - - -
Protease Type XIV - - -
Protease Type XVIII - - -
Pronase E - - -
Savinase - - -
Catalase - - -
Buffer + + +
THKOe23 Protease Type IX - - -
Protease Type XIII - - -
Protease Type XIV - - -
Protease Type XVIII - - -
Pronase E - - -
Savinase - - -
Catalase - - -
Buffer / - -

13. B-13
Catalase --> negative
6 proteases --> negative
Buffer solution -->
1. THKOe06 vs E. coli O157H7 --> totally inactivated
2. THKOe10 vs three pathogens --> totally inactivated
==> due to acids
3. THKOe04 vs E. coli O157H7 --> partially inactivated
4. THKOe23 vs E. coli O157H7 --> partially inactivated
5. THKOe06 vs Listeria --> partially inactivated
==> multiple factors

14. B-14
For antimicrobial test with
known compounds

15. B-15
Single tests MLB, pH 4.1, 100 μl
Acetaldehyde: 10, 20, 50, 100, 200 and 500 mg l-1
(ND)
Diacetyl: 10, 20, 50, 100, 200 and 500 mg l-1
(ND)
Ethanol: 100, 250, 500 and 1000 mg l-1
(Max 466 mg l-1
)
Acetic acid: 1, 2, 5, and 10 g l-1
(Max 1.88 g l-1
)
Lactic acid: 5, 7, 14 and 21 g l-1
(7.00 g l-1
)
Combination tests
MLB with 500 mg l-1
ethanol, 2 g l-1
acetic acid and 7 g l-1
lactic
acid, pH 4.1.
With or without additions of 200 mg l-1
acetaldehyde and 20
mg l-1
diacetyl.
--> All negative on pathogens

16. B-16
Conclusion
1. This is the first report of using O. oeni for
foodborne pathogen control.
2. Antimicrobial activity can be due to acids and
other factors.

17. B-17
Future Work
1. Continue to identify antimicrobial compounds.
2. Application evaluation: pathogens control in
foods, salad, fresh or cooked meats, and
probiotics (like vitamin pills).
3. Evaluate the antimicrobial activity by O. oeni
along and with others antimicrobials (H2
O2
)
4. Try more pathogens e.g. Staphylococcus
aureus, Bacillus cereus.