Characteristics of the Proteolytic Enzymes Produced by Lactic Acid Bacteria

Abstract

Over the past several decades, we have observed a very rapid development in the biotechnological use of lactic acid bacteria (LAB) in various branches of the food industry. All such areas of activity of these bacteria are very important and promise enormous economic and industrial successes. LAB are a numerous group of microorganisms that have the ability to ferment sugars into lactic acid and to produce proteolytic enzymes. LAB proteolytic enzymes play an important role in supplying cells with the nitrogen compounds necessary for their growth. Their nutritional requirements in this regard are very high. Lactic acid bacteria require many free amino acids to grow. The available amount of such compounds in the natural environment is usually small, hence the main function of these enzymes is the hydrolysis of proteins to components absorbed by bacterial cells. Enzymes are synthesized inside bacterial cells and are mostly secreted outside the cell. This type of proteinase remains linked to the cell wall structure by covalent bonds. Thanks to advances in enzymology, it is possible to obtain and design new enzymes and their preparations that can be widely used in various biotechnological processes. This article characterizes the proteolytic activity, describes LAB nitrogen metabolism and details the characteristics of the peptide transport system. Potential applications of proteolytic enzymes in many industries are also presented, including the food industry.

Optimization of Lactic Acid Production from Pineapple By-Products and an Inexpensive Nitrogen Source Using Lactiplantibacillus plantarum strain 4O8

“…This phenomenon is explained by the low protein content of the pineapple by-products used as a carbon source for the preparation of the fermentation broth [ 8 ]. Indeed, to ensure good growth of the lactic ferment and consequent production of LA, the production medium must contain a sufficient quantity of protein to meet the nitrogen requirements of the fermenting strain [ 26 ]. Moreover, this LA production was improved when the different production media were supplemented with BC, BF, and BBIP; these by-products would therefore be potential sources of amino acids and peptides that served as a nitrogen source for the lactic ferment.…”

Role of Exposure to Lactic Acid Bacteria from Foods of Animal Origin in Human Health

“…To ensure the supply of these essential nutrients, LAB possess proteolytic enzymes, bound to their cell walls, which degrade the proteins in the substrate, accumulating peptides and free amino acids. Some of the released peptides have been demonstrated to possess important bioactivities in the host [54]. In their fermentative processes, LAB-the main group of bacteria used for food and feed fermentations-release a number of bioactive metabolites, such as biogenic amines, exopolysaccharides, bacteriocins, and other biologically active, proteolytically released peptides [50][51][52].…”

“…To ensure the supply of these essential nutrients, LAB possess proteolytic enzymes, bound to their cell walls, which degrade the proteins in the substrate, accumulating peptides and free amino acids. Some of the released peptides have been demonstrated to possess important bioactivities in the host [ 54 ]. For instance, bacteriocinogenic strains of LAB can be added to foods as starter cultures, co-cultures, or bioprotective cultures, to improve food quality and safety, as reported in fermented meat and cheese [ 55 , 56 ].…”

Proteomic Analysis Explores Interactions between Lactiplantibacillus plantarum and Saccharomyces cerevisiae during Sourdough Fermentation

“…A previous study has indicated a positive correlation between the glucose dehydrogenase (GDH) activity in lactic acid bacteria and their ability to metabolize amino acids. Co-metabolism of citric acid and glutamate can result in higher amino acid conversion rates [44]. Finally, organic acids can improve the oxidation resistance of sourdough.…”