Feed enzyme preparation is a new type of feed additive that has emerged with the continuous development of feed industry and enzyme preparation industry in recent years. It has the functions of improving nutrient digestibility, improving the stability of compound feed quality, and reducing environmental pollution. As a kind of high-efficiency, non-toxic, non-side effects and environmentally friendly green feed additives, feed enzyme preparations have become the fastest growing and most powerful part of the world's industrial enzyme industry, and its application effects have been recognized worldwide.
At present, there are more than 20 kinds of feed enzymes in China, mainly including: amylase, protease, xylanase, β-mannanase, cellulase,β-glucanase, phytase and compound enzymes. These enzyme preparations can be divided into two categories: 1) Mainly degrade polysaccharides and biological macromolecular substances, including proteases, lipases, amylases, saccharification enzymes, cellulases, xylanases, and mannanases. The main function is to destroy the plant cell wall and fully release the cell contents; 2) Degrade phytic acid,β-glucan, pectin and other anti-nutritional factors, mainly including phytase, β-glucanase and Pectinase, its main function is to degrade the pectin components of cell wall xylan and intercellular substance, and improve the utilization rate of feed.
There are three major groups of microorganisms that produce enzyme preparations: filamentous fungi, yeasts, and bacteria, mainly using good air bacteria. The strains and usage of several main industrial enzymes are as follows:
Amylase hydrolyzes starch to produce pasty malto-oligosaccharides and maltose. It is mainly produced by submerged fermentation of Bacillus subtilis and Bacillus licheniformis of the genus Bacillus, and the latter produces thermostable enzymes. In addition, it is also produced by deep-layer and semi-solid fermentation with strains of Aspergillus and Rhizopus, which is suitable for food processing. Glucoamylase can hydrolyze starch into glucose, which is now almost all produced by Aspergillus niger submerged fermentation for sugar production, alcohol production, fermentation raw material processing, etc.
Protease is the enzyme with the most strains and production varieties. Use Bacillus licheniformis, Bacillus pumilus and Bacillus subtilis to produce bacterial protease by submerged fermentation; use Streptomyces and Aspergillus submerged fermentation to produce neutral protease and Aspergillus acid protease for leather depilation, fur softening, pharmacy and food industry; Some bacteria of the genus Mucor undergo semi-solid fermentation to produce rennet, which replaces the rennet originally extracted from calf stomachs in cheese manufacturing.
First, submerged fermentation is used to obtain Streptomyces cells. After immobilization, the glucose solution is converted into a syrup containing about 50% fructose. This syrup can be used in the food industry instead of sucrose. Using amylase, glucoamylase and glucose isomerase to produce fructose syrup from corn starch has become one of the emerging sugar industries.