# Selection of Antifungal Lactic Acid Bacteria Combinations in Dairy Models and Antifungal Molecule Identification

Marcia Leyva Salas, Mathilde Lemaitre, Marie-Bernadette Maillard, Florence Valence, Jérôme Mounier, Anne Thierry, Emmanuel Coton

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## To cite this version:

Marcia Leyva Salas, Mathilde Lemaitre, Marie-Bernadette Maillard, Florence Valence, Jérôme Mounier, et al.. Selection of Antifungal Lactic Acid Bacteria Combinations in Dairy Models and Antifungal Molecule Identification. Microbial Spoilers in Food 2017, Jun 2017, Quimper, France., 2017. hal-01559720

HAL Id: hal-01559720

https://hal.science/hal-01559720

Submitted on 10 Jul 2017

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# Selection of Antifungal Lactic Acid Bacteria
## Combinations in Dairy Models and Antifungal Molecule Identification

Marcia Leyva Salas<fnref n="1" />, <fnref n="2" />, Mathilde Lemaître<fnref n="1" />, Marie-Bernadette Maillard<fnref n="2" />, Florence Valence<fnref n="2" />, Jérôme Mounier<fnref n="1" />, Anne Thierry<fnref n="2" />, Emmanuel Coton<fnref n="1" />

## Context

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Dairy products are
susceptible
to acid-tolerant fungal
contaminants

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**Consequences:**
Food waste &
Economic losses

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**Solution:** Antifungal cultures are of growing interest as an alternative to chemical preservatives or a complement tool to hurdle technologies

## Objective

To characterize the antifungal activity of lactic acid bacteria combinations as adjunct cultures in dairy models

## Strategy & Results

### Screening Strategy

* Screening in 24 well plates

* 2 models: mimicking Cheese & Yogurt

* Strains added as adjunct cultures along with the acidifying starter

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1st screening:

1 acidifying starter/model

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Antifungal activity was higher in cheese than in yogurt model

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2nd screening:

2 acidifying starter/model

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The different acidifying starters tested did not modify the antifungal activity of the 12 strains with high antifungal activity

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Tested in combinations

10 binary and 3 ternary combinations

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Antifungal activity ≥ to that of commercial cultures
Species diversity potentially linked to molecule diversity

### Screening of the antifungal activity led to the selection of 5 antifungal strains

### 13 combinations with the 5 selected lactobacilli

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Antifungal
score:

3: total → 3
inhibition

2

1

0: no
inhibition → 0

3 binary combinations selected because of their higher antifungal activity than the strains alone

### Action spectrum tested against 10 spoiling fungi

- Mucor racemosus

- Phoma pinodella

- Penicillium commune

- Candida parapsilosis

- Yarrowia lipolytica

- Rhodotorula mucilaginosa

- Galactomyces geotrichum

- Meyerozyma guilliermondii

- Penicillium bialowiezense

- Trichosporon asahii

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Example of the antifungal activity against 4 fungal targets in cheese model for 2 A2 strains (individually or combined) in comparison with 2 commercial antifungal cultures (X and Y)

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The 3 combinations improved both antifungal activity and action spectrum

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The 3 combinations showed a higher antifungal activity than commercial cultures against the most resistant targets: *Y. lipolytica* and *G. geotrichum*

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The 3 combinations had a broad inhibition spectrum: 6-9 fungi of the 10 tested

### The 3 binary combinations (A1, A2 & A3) exhibited high antifungal activity and broad action spectrum

### Metabolomics using 4 chromatographic methods

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Antifungal molecules produced in significantly higher amounts by the 3 tested combinations in comparison to the controls

* HPLC-UV/RI Organic Acids (OA)

* LC-MS→ for Organic Acids (OA)

* GC-FID → for Fatty Acids (FFA)

* GC-MS→ for Volatile Compounds (VC)

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Different antifungal molecules produced in the tested models rises the question of the matrix effect

### Overall, 23 antifungal molecules produced in higher concentrations in the presence of at least 1 of the 3 selected antifungal combinations, compared to the control models

## Conclusions

The screening strategy was successful to select antifungal cultures active in dairy matrices. The 3 selected combinations and their metabolites are natural antifungal alternatives of interest for the dairy industry.

## Perspectives

The observed matrix-dependent effect shows the importance of *in situ* tests. Thus, challenge-tests are in process to determine the antifungal activity of the selected combinations in pilot-scale dairy products.

<footnote n="1">¹ Université de Brest, EA 3882 Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané</footnote>

<footnote n="2">² UMR1253 Science et Technologie du Lait et de l'Œuf, INRA, Agrocampus Ouest, 65 rue de Saint Brieuc, 35000 Rennes.</footnote>