Characterization of dual enzyme resulted from bicistronic expression of two β-glucanases in porcine cells

Many animal feed grains contain high beta-glucan in the cell wall. Pigs do not secret beta-glucanase to degrade the beta-glucan in their feed. The indigestible beta-glucan not only blocks the release of nutrients from the grain cell wall, but also increases the digesta viscosity in the gastrointestinal tract of pigs. Therefore, dietary beta-glucan significantly inhibits nutrient digestion and absorption in pigs. Transgenic expression of beta-glucanase in the digestive tract of pigs may offer a solution to solve this problem. In the current study, four artificial codon-optimized beta-glucanases genes was prepared and expressed in porcine cells. Only pBgA and pEgx showed high activity in transfected pig kidney cells. To improve the pH range and pH stability of beta-glucanase, the two beta-glucanases, pBgA and pEgx, were co-expressed in pig kidney cells and salivary gland cells by Linker A3 or 2A peptide. The resulting dual enzymes of pBgA3pEg and pBg2ApEg showed significantly enlarged pH range and significantly increased pH stability, as compared to parental enzymes. These results provide useful data for future study on increasing the feed digestibility of pigs by transgenic expression of beta-glucanase in their salivary glands.