Effects of tyrosine decarboxylase negative strains from Harbin dry sausage on the growth and tyramine production of foodborne pathogens

Production and transformation of biogenic amines in different food products by the metabolic activity of the lactic acid bacteria

Protein-rich diets often contain high quantities of biogenic amines (BAs), notably histamine and tyramine, which pose substantial health hazards owing to their toxicity. BAs are primarily produced by the microbial decarboxylation of free amino acids. Lactic acid bacteria (LAB) can either produce BAs using substrate-specific decarboxylase enzymes or degrade them into non-toxic compounds using amine-degrading enzymes such as amine oxidase and multicopper oxidase. Furthermore, LAB may inhibit BA-producing microbes by generating bioactive metabolites, including organic acids and bacteriocins. This paper thoroughly explores the processes underlying BA production and degradation in LAB, with a focus on the diversity of enzymes involved. Metabolic mapping of LAB strains at the genus and species levels reveals their involvement in BA metabolism, from production to degradation. The phylogenetic-based evolutionary relatedness of BA-producing and BA-degrading enzymes among LAB strains sheds light on their functional adaptability to various metabolic needs and ecological settings. These findings have significant practical implications for establishing better microbial management strategies in food production, particularly through strategically using starter or bioprotective cultures to reduce BA buildup. By highlighting the evolutionary and metabolic diversity of LAB, this review helps to optimize industrial fermentation processes, improve food safety protocols, and advance future research and innovation in BA management, ultimately protecting consumer health and supporting regulatory compliance.

Multicopper Oxidase from Lactobacillus hilgardii: Mechanism of Degradation of Tyramine and Phenylethylamine in Fermented Food

Elevated levels of biogenic amines (BAs) in fermented food can have negative effects on both the flavor and health. Mining enzymes that degrade BAs is an effective strategy for controlling their content. The study screened a strain of Lactobacillus hilgardii 1614 from fermented food system that can degrade BAs. The multiple copper oxidase genes LHMCO1614 were successfully mined after the whole genome protein sequences of homologous strains were clustered and followed by homology modeling. The enzyme molecules can interact with BAs to stabilize composite structures for catalytic degradation, as shown by molecular docking results. Ingeniously, the kinetic data showed that purified LHMCO1614 was less sensitive to the substrate inhibition of tyramine and phenylethylamine. The degradation rates of tyramine and phenylethylamine in huangjiu (18% vol) after adding LHMCO1614 were 41.35 and 40.21%, respectively. Furthermore, LHMCO1614 demonstrated universality in degrading tyramine and phenylethylamine present in other fermented foods as well. HS-SPME-GC-MS analysis revealed that, except for aldehydes, the addition of enzyme treatment did not significantly alter the levels of major flavor compounds in enzymatically treated fermented foods (p > 0.05). This study presents an enzymatic approach for regulating tyramine and phenylethylamine levels in fermented foods with potential applications both targeted and universal.

Autochthonous Cultures to Improve Safety and Standardize Quality of Traditional Dry Fermented Meats

Traditional dry fermented meat products are obtained artisanally in many countries, where they represent a gastronomic heritage well distinguished from industrial counterparts. This food category is most often obtained from red meat, a food commodity that is under attack because of evidence of increased risk of cancer and degenerative diseases with high consumption. However, traditional fermented meat products are intended for moderate consumption and gastronomic experience, and, as such, their production must be continued, which would also help safeguard the culture and economy of the geographical areas of origin. In this review, the main risks attributed to these products are considered, and how these risks are reduced by the application of autochthonous microbial cultures is highlighted by reviewing studies reporting the effects of autochthonous lactic acid bacteria (LAB), coagulase negative staphylococci (CNS), Debaryomyces hansenii and Penicillium nalgiovense on microbiological and chemical safety and on sensory attributes. The role of dry fermented sausages as a source of microorganisms that can be beneficial to the host is also considered. From the results of the studies reviewed here it appears that the development of autochthonous cultures for these foods can ensure safety and stabilize sensory characteristics and has the capacity to be extended to a larger variety of traditional products.