The yeast surface displayed rice α-galactosidase II (YSD rice α-Gal II) was generated with the pYD1 vector. The expression and cultural conditions for the improvement of production of YSD rice α-Gal II were optimized. The results showed that several induction factors, which were the initial cell density, inoculation ratio, galactose (inducer) concentration, induction time and temperature, determined the activity and expression efficiency of YSD rice α-Gal II. Meanwhile, the medium composition also affected its activity and production. Moreover, the production of YSD rice α-Gal II was further improved by continuous feeding of galactose in the fermenter level. The highest production was obtained at an initial cell density of OD₆₀₀ = 2.9, 2% inoculation ratio, and 2% galactose, with 0.6 g/L compound nitrogen source ((NH₄)₂SO₄/urea = 2/1, w/w) and 5 g/L sucrose, followed by continuous feeding of galactose (20 g/L with flow rate of 1.5 mL/h). At such conditions, the enzyme activity and productivity reached to 676.2 U/g (DCW) and 1548.5 U/L, respectively, 26.4- and 63.7-fold to that before optimization. The results provided a basic and effective strategy for the industrial production of YSD rice α-Gal II.

酵母表面展示的水稻α-半乳糖苷酶II（YSD水稻α-GalII）是由pYD1载体产生的。优化了提高YSD水稻α-GalII产量的表达和培养条件。结果表明，YSD水稻α-GalII的初始细胞密度，接种率，半乳糖（诱导剂）浓度，诱导时间和温度等多种诱导因子决定了其活性和表达效率。同时，培养基组成也影响其活性和产量。此外，通过在发酵罐中连续喂入半乳糖，进一步提高了YSD水稻α-GalII的产量。在OD ₆₀₀的初始细胞密度下获得了最高产量 = 2.9，接种率为2％，半乳糖为2％，用0.6 g / L的复合氮源（（NH ₄）₂ SO ₄ /脲= 2/1，w / w）和5 g / L的蔗糖，然后连续喂半乳糖（20 g / L，流速为1.5 mL / h）。在这种条件下，酶的活性和生产率分别达到676.2 U / g（DCW）和1548.5 U / L，分别是优化前的26.4和63.7倍。结果为YSD水稻α-GalII的工业化生产提供了基本有效的策略。