Emerging Challenges in Food and Environmental Safety: The Role of Bacteria in Risk Mitigation

The growing pressure on food production and the environmental impact of intensive livestock farming have made it urgent to identify sustainable and safe protein sources. In this context, the present thesis explores the role of bacteria, particularly lactic acid bacteria (LAB) and other microorganisms isolated from food matrices, as biotechnological tools for mitigating risks related to food and environmental safety. The main objective was to evaluate how the proteolytic and biodegradative activities of bacteria can contribute, on one hand, to reducing the allergenicity of novel protein sources, and on the other, to limiting the impact of emerging environmental contaminants. First, the research focused on the edible insect Hermetia illucens (black soldier fly, BSF), considered a promising alternative source of proteins and lipids with high nutritional value. However, the presence of pan-allergens such as arginine kinase (AK) and tropomyosin (TPM), homologous to those found in crustaceans and mites, poses a risk for sensitized consumers. This thesis demonstrated that LAB fermentation can be an effective strategy to reduce the immunoreactivity of these proteins. In silico and in vitro analyses showed that several LAB strains possess complex proteolytic systems based on cell-envelope proteinases (CEP), such as PrtP and PrtR, capable of degrading IgE-binding epitopes. Experiments conducted in situ on BSF powder (BSFP) revealed that LAB fermentation, under specific conditions of temperature and nutrient supplementation, led to a decrease in pH, modification of the protein profile, and a significant reduction in the immunological reactivity of AK and TPM. In addition, the techno-functional properties of fermented and non-fermented BSFP were also characterized. Both were mixed with wheat flour and used to prepare doughs and cookies, analyzing their rheological properties (dough) and evaluating color, moisture, and hardness (cookies). Results indicated that fermentation influenced the physico-chemical properties of BSFP, dough, and cookies, and suggested a potential reduction in allergenicity of AK. These results suggest that the use of LAB may represent a practical solution to enhance the safety of insect-based products, supporting their integration into Western diets and contributing to more sustainable food systems. In parallel, the thesis addressed the issue of environmental safety by analyzing the ability of bacterial strains isolated from food matrices to adapt to stress conditions and degrade emerging contaminants. In particular, the behavior of thirteen bacterial strains toward paroxetine, a fluorinated antidepressant difficult to remove through conventional wastewater treatment processes, was investigated. Some strains demonstrated the ability to adapt and remain metabolically active even in the presence of contaminants, suggesting that complex microbial–pollutant interactions may occur and warrant further investigation. Overall, the thesis highlights how bacteria can act as key allies in the transition toward a more sustainable food and environmental model. Their versatility, expressed through their capacity to degrade both allergenic proteins and persistent compounds, lays the groundwork for the development of integrated biotechnological strategies aimed at enhancing safety, sustainability, and innovation in the food and environmental sectors.