Seila Agún

Background/Objectives: Tallaga cheese is an artisanal form of traditional Egyptian soft white Damietta cheese, characterized by high moisture, elevated salinity, and a limited shelf life, which collectively increase its vulnerability to microbial contamination. Typically produced from raw or minimally heated cow or buffalo milk, Tallaga cheese represents a relevant model for studying emerging food safety challenges. Methods/Results: This study revealed marked variability among commercial samples and, unexpectedly, a general absence of typical lactic acid bacteria (LAB) such as Lactococcus spp. Instead, enterococci, microorganisms increasingly associated with antimicrobial resistance and virulence traits, emerged as the dominant LAB group, with the detection of Enterococcus faecium strains posing particular concern for dairy safety. To address these challenges, the antimicrobial potential of isolated LAB was evaluated against Latilactobacillus sakei (CECT 906). Twelve bacteriocin-producing strains were identified: ten Enterococcus faecalis, one E. faecium, and one Lactococcus lactis. Enterococci demonstrated robust tolerance to stress conditions, including high salt concentrations, emphasizing their persistence in dairy environments. Given the relevance of controlling resistant and potentially virulent strains such as E. faecium, the bioprotective capacity of two bacteriocinogenic L. lactis strains (IPLA 1064 and AHRI ST9) was assessed using a laboratory-scale cheese model. Both strains effectively inhibited E. faecium AHRI CH4, achieving reductions of 2.6 and 3.6 log units (99.9%). Conclusions: These findings underscore the relevance of bacteriocin-producing L. lactis as natural biopreservatives to mitigate emerging threats related to antimicrobial-resistant food-borne pathogens in dairy products.

Antimicrobial resistance (AMR) has emerged as a global health challenge, sparking worldwide interest in exploring the antimicrobial potential of natural compounds as an alternative to conventional antibiotics. In recent years, one area of focus has been the utilization of bacteriophages and their derivative proteins. Specifically, phage lytic proteins, or endolysins, are specialized enzymes that induce bacterial cell lysis and can be efficiently produced and purified following overexpression in bacteria. Nonetheless, a significant limitation of these proteins is their vulnerability to certain environmental conditions, which may impair their effectiveness. Encapsulating endolysins in vesicles could mitigate this issue by providing added protection to the proteins, enabling controlled release, and enhancing their stability, particularly at temperatures around 4 °C. In this work, the chimeric lytic protein CHAPSH3b was encapsulated within non-ionic surfactant-based vesicles (niosomes) created using the thin film hydrating method (TFH). These protein-loaded niosomes were then characterized, revealing sizes in the range of 30–80 nm, zeta potentials between 30 and 50 mV, and an encapsulation efficiency (EE) of 50–60%. Additionally, with the objective of exploring their potential application in the food industry, these endolysin-loaded niosomes were incorporated into gelatine films. This was carried out to evaluate their stability and antimicrobial efficacy against Staphylococcus aureus.

Antimicrobial resistance (AMR) has become a worldwide health problem. Consequently, there is a global interest in the study of the antimicrobial activity of natural compounds as an alternative to antibiotics. One of the possibilities studied during the last years is the use of bacteriophages and their derived proteins. More specifically, phage lytic proteins or endolysins are specific enzymes that cause cell lysis and can be easily produced and purified after overexpression in bacteria. However, one of the major disadvantages of these proteins is their sensitivity to some environmental conditions that can reduce their efficiency. The use of vesicles for endolysin encapsulation could help overcome this disadvantage, offering an additional protection to the protein and allowing its controlled release and long-term stability.

This article discusses the use of Near Infrared spectroscopy (NIR) combined with multivariate classification methods for detecting bacterial contamination in milk in the dairy industry. In a first experiment, the study found that Nir was accurate and reliable in detecting the presence of biofilms in milk. Our results showed that the technology was effective in distinguishing between contaminated and uncontaminated samples with an area under the ROC curve (AUC) greater than 99%. It was also effective in classifying the samples belonging to different strains. In a second experiment, we used the same methodology to assess their effectiveness in detecting bacterial contamination proportions in milk. Our results showed that the technology was effective in classifying milk samples contaminated with four different bacteria and uncontaminated controls with an AUC greater than 97%. Moreover, results were still good when data from all bacteria were analyzed together, even at low bacterial concentrations, obtaining an average precision of 70%. These results demonstrate the potential of this technology to be used as a rapid and accurate method for identifying bacterial contamination in the dairy sector.