Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Engineering, China Agricultural University, Beijing 100083, China.
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
Food Chem. 2020 Dec 1;332:127438. doi: 10.1016/j.foodchem.2020.127438. Epub 2020 Jul 2.
β-N-acetylhexosaminidases have attracted much attention in recent years due to their potential application in oligosaccharide production, in particular lacto-N-triose II (LNT2) and lacto-N-neotetraose (LNnT) synthesis, which can be further used as backbone precursors for human milk oligosaccharides. A novel β-N-acetylhexosaminidase gene from Tyzzerella nexilis (TnHex189) was heterologously expressed in Bacillus subtilis. The highest β-N-acetylhexosaminidase activity of 14.5 U mL was obtained in a 5-L fermentor by fed-batch fermentation for 27 h. TnHex189 was optimally active at pH 5.0 and 45 °C. It efficiently synthesized LNT2 with a conversion ratio of 57.2% (4.7 g L). The synthesized LNT2 was further converted to LNnT by a reported β-galactosidase (BgaD-D) in 8 h, with a conversion ratio of 17.3% (6.1 g L). These unique synthesis activities may make this enzyme a good candidate for the food industry.
β-N-乙酰氨基葡萄糖苷酶近年来因其在寡糖生产中的潜在应用而受到广泛关注，特别是在乳三糖 II（LNT2）和乳四糖（LNnT）的合成方面，它们可以进一步用作人乳寡糖的骨干前体。从 Tyzzerella nexilis（TnHex189）中异源表达了一种新型的β-N-乙酰氨基葡萄糖苷酶基因。通过 27 小时的分批补料发酵，在 5L 发酵罐中获得了 14.5 U/mL 的最高β-N-乙酰氨基葡萄糖苷酶活性。TnHex189 在 pH5.0 和 45°C 下具有最佳活性。它能够以 57.2%（4.7g/L）的转化率高效合成 LNT2。合成的 LNT2 进一步在 8 小时内被报道的β-半乳糖苷酶（BgaD-D）转化为 LNnT，转化率为 17.3%（6.1g/L）。这些独特的合成活性可能使该酶成为食品工业的一个很好的候选酶。
