Cadaverine (1,5-pentanediamine) is the most important precursor for nylon PA5X, which has an extremely competitive market due to the high consumption of engineered plastics and fibers. The key enzyme lysine decarboxylase is in desperate need for industrial bio-based cadaverine production. In this study, new lysine decarboxylases have been mined by peptide pattern recognition for the high-level production of cadaverine. The predicted enzymes were expressed in E. coli and analyzed as whole-cell biocatalysts. Two outstanding recombinant enzymes from Edwardsiella tarda and Aeromonas sp. (LdcEt and LdcAer, respectively), were further purified and characterized. The optimal pH and temperature for LdcEt and LdcAer were pH 7, 55 °C and pH 6, 50 °C, respectively. These two enzymes were stable over the pH range of 5–7 during 24 h incubation. Both of them still had activity after being incubated at pH 8. LdcEt and LdcAer also have good thermostability with a half-life of 14.5 h and 20.3 h at 60 °C, respectively. The kinetic analysis showed that they have high catalytic efficiency as the k_cat/K_m (LdcEt: 243.28 s⁻¹ mM⁻¹; LdcAer: 266.86 s⁻¹ mM⁻¹) was the highest when compared for all the related studies. The whole cell conversion by LdcEt with 0.1% (v/v) Triton X-100 can convert 100% 2 M L-lysine HCl to cadaverine in 2 h and the cadaverine productivity was high up to 103.47 ± 4.37 g L⁻¹ h⁻¹. The in vitro studies further found that unpurified cell-lysates of LdcEt had relatively higher activity compared to the whole cell conversion. Meanwhile, 0.4 mg mL⁻¹ purified LdcEt and LdcAer can efficiently produce 165.96 ± 1.41 g L⁻¹ and 155.84 ± 4.63 g L⁻¹ cadaverine only in 0.5 h, respectively. The high specific activity, pH, thermo-stability, and catalytic efficiency in vivo and in vitro, combined with simultaneous cell treatment with Triton X-100 and the bioconversion process, provide LdcEt with great potential in the economic and efficient production of cadaverine at the industrial scale.

中文翻译：

---

生物尼龙5X的进展：新型的赖氨酸脱羧酶用于尸体的高产量生产

尸胺（1,5-戊二胺）是尼龙PA5X的最重要前体，由于工程塑料和纤维的大量消费，其具有极强的市场竞争力。关键的赖氨酸脱羧酶迫切需要基于生物的尸胺工业生产。在这项研究中，新的赖氨酸脱羧酶已经通过肽模式识别被开采出来，以用于尸胺的高水平生产。预测的酶在大肠杆菌中表达，并作为全细胞生物催化剂进行分析。从两位杰出的重组酶迟钝爱德华氏菌和嗜sp。（分别为LdcEt和LdcAer）被进一步纯化和鉴定。LdcEt和LdcAer的最佳pH和温度分别为pH 7、55°C和pH 6、50°C。两种酶在24 h的pH范围5-7内都是稳定的。它们在pH 8下孵育后仍然具有活性。LdcEt和LdcAer在60°C下的半衰期分别为14.5 h和20.3 h，具有良好的热稳定性。动力学分析表明它们具有较高的催化效率，为k _cat / K _m（LdcEt：243.28 s ^-1 mM ^-1 ; LdcAer：266.86 s ^-1 mM ^-1。与所有相关研究相比，）最高。通过LdcEt全细胞转化，含有0.1％（V / V）的Triton X-100可在100％的2M转换大号赖氨酸HCl以尸胺在2小时和尸胺生产率高达103.47±4.37克L- ^-1 ħ ^{- 1}。在体外研究进一步发现，LdcEt的未纯化细胞裂解物相比，全细胞转化具有相对较高的活性。同时，仅在0.5小时内，0.4 mg mL ^-1纯化的LdcEt和LdcAer可以分别有效生产165.96±1.41 g L ^-1和155.84±4.63 g L ^-1尸胺。在体内和体外具有较高的比活度，pH，热稳定性和催化效率体外，结合Triton X-100的同时细胞处理和生物转化工艺，在工业规模的尸胺经济高效生产中，LdcEt具有巨大的潜力。