# Impact of iron on structuration & functioning of cheese microbial communities

Mahtab Shoukat, Eric Dugat-Bony, Vincent Hervé, Dominique Swennen, Pascal Bonnarme

► To cite this version:

Mahtab Shoukat, Eric Dugat-Bony, Vincent Hervé, Dominique Swennen, Pascal Bonnarme. Impact of iron on structuration & functioning of cheese microbial communities. Food Micro 2022 (Next Generation Challenges in Food Microbiology), Aug 2022, Athens, Greece. hal-03986314

HAL Id: hal-03986314

https://hal.science/hal-03986314

Submitted on 13 Feb 2023

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Distributed under a Creative Commons Attribution 4.0 International License
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## Results

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A significant difference in volatile compound profiles was observed among the iron-supplemented model cheeses.

Microbial interactions are decisive factors in cheese quality and safety. Microorganisms require certain crucial nutrients for functioning, and iron is on top of the nutrients list. Iron is involved in various metabolic, physiological, and biochemical processes such as respiration, gene regulation, enzyme cofactor, DNA, fatty acids, and amino acids syntheses. However, cheese is a highly iron-restricted habitat (1.24mg/Kg) due to its very low iron quantity, presence of iron-chelating proteins (lactoferrin), and low iron diffusion index. Consequently, **iron competition** is one of the mediators of **microbe-microbe interactions** in cheese rinds. It has been demonstrated that iron is a limiting factor for the growth of many surface ripening bacteria. Cheese ripening microorganisms have adapted strategies to combat the iron-restricted environment like the iron acquisition system. They produce **siderophores** (iron chelators with high Fe⁺³ affinity) under iron-starved conditions. Understanding iron's role in cheese ripening microbes is of utmost importance due to its crucial role in various mechanisms.

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## Objectives

The aims of this study were to

* Evaluate the capacity of iron supplementation to disturb the cheese ecosystem.

* Identify the concentration thresholds of iron required to observe such disturbance.

* Investigate the **microbe-microbe interactions** under a sufficient iron environment

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## Results

<figure><img src="image_9.png" /><figcaption>Glutamicibacter arilaitensis</figcaption></figure>

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One-way ANOVA depicts *Glutamicibacter arilaitensis* (p-value<0.05***) and *Brevibacterium aurantiacum* growth increased linearly with increased iron concentration at D28 (p-value<0.05**).

<figure><img src="image_11.png" /><figcaption>Geotrichum candidum</figcaption></figure>

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*Hafnia alvei* and *Geotrichum candidum* count decreased with high iron concentrations at D28 (p-value<0.05**).

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## Conclusion

* Iron supplementation can significantly modify the growth kinetic of some microorganisms used in the RMC and the volatile compounds profiles.

* Iron has a pronounced effect on microbial communities as it can significantly influence microbial dynamics and interactions.

* **8-15µM Fe** concentration identified as the Fe threshold level to disturb the cheese ecosystem in the tested conditions.

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## Future Work

* Investigate **biochemical pathways** involved in **iron homeostasis**, **oxidative stress**, and **aroma compounds** production (e.g. sulphur metabolism) to understand the effect of iron on the ecosystem's equilibrium.

* Understand the role of iron in the cheese microbial ecology (e.g. resilience and structuration) by applying **multi-omics techniques**.

## Acknowledgement

E-MUSE project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement N° 956126.

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Marie Skłodowska-Curie Actions

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## References

* Monnet, C., Back, A., & Irlinger, F. (2012). Growth of aerobic ripening bacteria at the cheese surface is limited by the availability of iron. *Applied and environmental microbiology*, 78(9), 3185-3192.

* Monnet, C., Landaud-Liautaud, S., Bonnarme, P., & Swennen, D. (2015). Growth and adaptation of microorganisms on the cheese surface. *FEMS microbiology letters*, 362(1), 1-9.

* Dugat-Bony, E., Straub, C., Teissandier, A., Onesime, D., Loux, V., Monnet, C., ... & Bonnarme, P. (2015). Overview of a surface-ripened cheese community functioning by meta-omics analyses. *PloS one*, 10(4), e0124360.