Efficient Isolation, Expression and Improvement Technique System for Feed Enzymes in China

Abstract

Supplementation of hydrolytic enzymes in feed can decrease the effect of anti‐nutritional factors and increase feed conversion rate by 5‐10%. Consequently, this practice can improve the efficiency of livestock production and reduce environmental contamination. The authors have developed a highly efficient platform to enrich the genetic resources of several enzymes, characterize and assess their application potentials, and achieve high‐yield production. These works make the production of novel enzymes cost‐effective and commercially valuable.Firstly, a new technology system was set up, which can directly clone full‐length genes and screen objective genes from environmental metagenomic or transcriptomic nuclear acid. Using these methods, 184 genes coding for enzymes have been identified in short time. The enzymes showed different properties including high catalytic efficiency, thermophilic, acidophilic, or protease‐resistance. Secondly, great contributions were made in the structure and function relationship research of enzyme proteins. An efficient screening vector system was constructed based on extracellular fusion mutant proteins, optimized the protein engineering system for enzyme improvement, and obtained several improved enzymes with excellent properties and application potentials. Third, another great finding was identification of several key factors in Pichia expression system and verification of their function. Based on these knowledge, a high‐yield expression system of 5‐50 mg/mL was developed for large‐scale, cost‐effective production of enzymes, including phytase, xylanase, glucanase, mannannase, and α‐galactosidase.