Mitigating health risks through targeted microbial interventions

Author: Igor Baroja-Careaga, PhD, researcher in Molecular Biology, Esneki Zentroa (Leartiker S.COOP)

Biogenic amines (BAs) are nitrogenous compounds formed primarily by microbial decarboxylation of amino acids. In food products, they can accumulate to levels that pose health risks, including histamine poisoning and hypertensive crises due to tyramine ingestion ¹². Fermented foods, particularly cheeses, are significant sources of BAs due to their complex microbial consortia and the metabolic activities occurring during ripening ³. While lactic acid bacteria contribute positively to flavor, texture, and preservation, some strains also possess decarboxylase activity, leading to BA accumulation and the health risks associated with it ⁴⁵. Understanding microbial community dynamics at a genes level, has revolutionized food microbiology, allowing for precise identification of microbial capabilities and metabolic pathways ⁶.

In this study, BA-degrading capacities of different strains have been identified and selected manipulating microbial communities, to reduce BA accumulation in cheese while maintaining organoleptic quality.

Experimental Approach and Results

At Leartiker’s Dairy Center, a pilot plant and specialized laboratories enable controlled cheese production and in-depth monitoring of microbial and biochemical changes during ripening. In the present study, we confirmed that pressed cheeses commonly accumulate significant levels of biogenic amines (BAs), particularly tyramine and histamine, as a result of the metabolic activity of indigenous bacteria.

To address this issue, we tested the incorporation of Lactobacillus casei strains with documented BA-degrading capabilities into pressed cheese production. Specifically, we compared two strains from the Molecular Microbiology group of the IPLA-CSIC (4a and 5b) ⁷—selected for their BA-degrading activity, including Lacticaseibacillus casei harboring the mco gene encoding multicopper oxidase (a laccase enzyme involved in BA degradation)—with a widely used commercial L. casei strain.

Cheeses inoculated with these strains underwent standard ripening, followed by BA quantification using ultra-high performance liquid chromatography (UHPLC) ⁸. The results indicated that the IPLA-CSIC isolates effectively reduced BA levels, particularly tyramine (9.9% of histamine and 24.2% of tyramine). Interestingly, the commercial L. casei strain also contributed to BA reduction, suggesting that BA may be degraded by alternative mechanisms even in the absence of the mco gene (7.8% of histamine and 30% of tyramine).

No substantial differences were observed among the L. casei strains in terms of their overall ability to reduce BAs. However, among the tested strains, L. casei 5b achieved the greatest absolute reduction of histamine during cheese ripening (17.5%). In terms of tyramine degradation, all L. casei strains demonstrated effective reduction, with the commercial starter standing out due to a higher absolute reduction. Nevertheless, the differences observed were not statistically significant.

Conclusion and Future Perspectives

This study highlights the potential of targeted microbial selection in reducing BA content in cheese, offering a promising approach to enhance food safety without compromising product quality. The use of Lactobacillus casei strains, particularly those with known BA-degrading capabilities, resulted in significant reductions in tyramine and histamine during ripening. Notably, the effectiveness of the commercial strain—even in the absence of the mco gene—suggests that alternative degradation pathways may exist, or that competition with producer bacterial strains, potentially inhibiting their growth, could also play a meaningful role and warrants further investigation.

Moving forward, future studies should aim to elucidate the specific enzymatic pathways involved in BA degradation beyond multicopper oxidases, as well as explore synergistic effects when combining multiple strains. It will also be essential to validate these findings at an industrial scale, under varying milk sources, cheese types, and ripening conditions. In parallel, genomic and transcriptomic tools could assist in the development of microbial consortia tailored for both safety and sensory excellence.

Ultimately, the goal is to integrate precision microbial management strategies into dairy production workflows, enabling the creation of cheeses with consistently low—ideally undetectable 0 mg/kg —levels of BAs at the time of consumption, thereby contributing to safer and healthier fermented foods.

Acknowledgments

We gratefully acknowledge the Molecular Microbiology group from IPLA-CSIC (Instituto de Productos Lácteos de Asturias, Spain) for generously providing the bacterial strains used in this study. Their support has been essential for the development of this work.

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