As global milk production continues to rise, the disposal of expired milk contributes to environmental pollution and valuable resource wastage. This study presents the development of a novel L-arabinose isomerase, designatedBmAIase12, and its application in the enzymatic recycling of expired milk.BmAIase12 exhibited a specific activity of 10.7 U/mg and showed optimal performance at 50 °C and pH 7.0. Furthermore, it exhibited higher activity than most other L-arabinose isomerases. It converted D-galactose into D-tagatose with a high conversion ratio of 53.3% after 48 h at 50 °C. The conversion efficiency of expired milk to D-tagatose was recorded at 40.62%, resulting in a maximum tagatose yield of 1.625 g/L. This was accomplished through the incorporation of β-galactosidase (120 U/mL) andSaccharomyces cerevisiae(30 mg/mL) to hydrolyze lactose and metabolize glucose, followed by the addition of 3 U/mL ofBmAIase12. Ultimately, following purification, the purity of tagatose was determined to be 98%, and the final yield was 29.8%. These results suggest thatBmAIase12 may serve as a promising enzyme for D-tagatose production due to its high conversion yield.
Ning Xie,Yiting Liu,Haowei Kang,Xurui Li,Qiang Weng,Xingming Ning,Pei Chen,Xinbing Chen,Zhongwei An
To develop the anion exchange membranes (AEMs) with enhanced alkaline stability and superior performance, a series of high-density hydrophilic segment poly(carbazole)-based AEMs (designated as PBOMC-R) incorporating cation-dipole interaction were synthesized via step-feeding polymerization in this work. Among them, the comparison of different cationic groups in cation-dipole interaction for properties of the AEMs were emphatically discussed. The results indicated that the PBOMC-R (IEC = 1.90–2.19 mequiv. g −1 ) possessed appropriate water uptake and excellent dimensional stability. Theoretical simulations revealed that the cation-dipole interaction resulted from different cation type varied with an order TMA > PYR > DMI > PIP, and a reinforced cation-dipole interaction could be obtained through choosing a proper cationic group. While a stronger interaction force could more readily gather cationic groups to form a larger hydrophilic region for ion transport, which is consistent with the rule of microscopic morphology. Thus, the AEM PBOMC-TMA with the most potent cation-dipole interaction displayed the highest ionic conductivity, reaching 188.2 mS cm −1 at 80 °C. After the alkaline aging test (2 M NaOH, 80 °C, 1080 h), the membranes retained 85.1–95.1 % ionic conductivity, validating exceptional alkaline durability. Fuel cell tests demonstrated that PBOMC-TMA attains 779 mW cm −2 peak power density and a sustained 100 h operation at 0.03 mV h −1 voltage decay rate, thereby suggesting significant technological potential for alkaline fuel cell applications.
危险品化学品经营许可证（带存储）