Microbial transglutaminase in food biotechnology: from biochemical mechanisms to industrial applications.

Microbial transglutaminase (mTG) is an enzyme produced by actinomycetes, predominantly by filamentous bacteria belonging to the genus Streptomyces. These microorganisms are the best-studied and most microbiologically exploited natural producers of TG. It catalyzes the formation of isopeptide bonds between glutamine and lysine residues in proteins, which alters the protein's structure and functionality. This enzymatic activity is widely applied in the food industry, where it is particularly useful in modifying the texture, binding properties, and overall quality of protein products. The primary application of mTG in food production lies in its ability to mimic the functional properties of gluten, making it valuable in the creation of gluten-free products. By facilitating the binding of various ingredients such as starches and plant proteins, mTG helps produce products with similar texture and elasticity to those made with gluten, which is crucial for individuals with celiac disease or gluten intolerance. Beyond gluten-free applications, mTG is also employed in the production of meat substitutes, where it enhances the texture and cohesion of plant-based ingredients, as well as in bakery and confectionery products. Additionally, mTG is utilized in the development of organic materials, such as microcapsules and enzymatic carriers, owing to its calcium-independent activity, broad substrate specificity, and high stability across a wide range of pH and temperatures. The properties of this enzyme can be successfully used in the biotechnology industry. Looking forward, mTG is expected to play a significant role in the expansion of functional foods, plant-based diets, and advanced biomaterials. However, there are growing concerns about its safety, particularly regarding potential immunogenic reactions and its long-term impact on consumer health. To mitigate these risks, further research on the biological effects of mTG is essential, especially in the context of its microbial origin, molecular structure, and interaction with human proteins. Additionally, stricter regulations and clear labeling of products containing mTG will be necessary to ensure consumer safety and confidence in its widespread use. KEY POINTS: • Microbial transglutaminase is produced by actinomycetes via fermentation. • mTG is a microbial enzyme that modifies protein structure and functionality. • mTG is key to future functional foods. • Labeling of mTG in foods is vital for consumer trust and safety. • Enzyme mTG boosts cohesion in meat substitutes and bakery goods.