The Role of Alkaline Protease in Feed Production

Alkaline protease refers to the enzyme that can hydrolyze protein peptide bonds under alkaline conditions, and its optimal pH is within the range of 9-11. It is widely used in industries such as detergents, food, medical, brewing, silk, and leather.

Alkaline protease enzyme, also known as serine protease. The commonly used types are Novo protease and Carsberg protease, which have similar properties and structures. They respectively contain 275 and 274 amino acid residues, and are composed of a polypeptide chain. They are stable at pH 6-10, and quickly become inactive at pH below 6 or above 11. Their active center contains serine, thus they are named serine protease. They not only hydrolyze peptide bonds, but also have the functions of hydrolyzing amide bonds, ester bonds, and trans-esterification and trans-peptidation. Due to the specificity of the enzyme, it can only hydrolyze proteins, but can't act on substances such as starch and fat. They generally appear as powders or microspheres.

Sources of alkaline protease

The main source of alkaline protease enzyme is microbial extraction. Bacillus is the most commonly studied and applied microbe, especially Bacillus subtilis, but there are also a small number of other bacterial species, such as Streptomyces.

The production capacity and enzyme activity and stability of natural strains often cannot meet the needs of industrial production, so the strains need to be screened and improved. Commonly used methods include mutation, genetic engineering, protein engineering, and spore heat treatment. The main objectives are to increase enzyme activity, stability (heat and alkaline resistance), antioxidant properties, and anti-chelating properties.

Widespread use of alkaline protease enzyme in feed

In animal feed, proteins can provide peptides and amino acids for animals. Animals can produce some proteases to digest proteins, and their digestion rate is generally 80% to 90%. This can cause a certain degree of waste. Therefore, adding appropriate amounts of alkaline protease enzyme additives to feed can improve feed utilization to some extent.

Alkaline protease is a type of proteinase with a wide substrate specificity. People generally believe that the pH value in the stomach is very low, and alkaline protease will become inactive in the stomach environment. However, feed stays in the stomach for a limited time, so the protein in the feed may not be well hydrolyzed, and alkaline protease enzyme will not be decomposed in the stomach. The undigested feed and alkaline protease will enter into the small intestine, where they will continue to be broken down and absorbed.

In the small intestine, pH changes from acidic to slightly alkaline. At this time, the advantages of alkaline protease are manifested, and it does not compete with gastric protease. Instead, the two complement each other. Therefore, alkaline protease enzyme will not affect the normal digestion and absorption of feed in the stomach. When the undigested feed enters the small intestine, alkaline protease can further break down the undigested protein, which can ultimately be absorbed by animals and improve feed utilization, thereby increasing economic benefits.

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