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2008 1

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Preparation of D-lysine by chemical reaction and microbial asymmetric transformation

LIU Yi, JIAO Qingcai, YIN Xiaoxing

《化学科学与工程前沿（英文）》 2008年第2卷第1期页码 40-43 doi: 10.1007/s11705-008-0023-2

摘要： The DL-lysine crystals from the racemization of L-lysine was treated as substrate with AS1.1009 intact cells as biocatalysts to produce crystalline D-lysine with a yield of 56.6% from the reaction mixture after simple purification. In the presence of 0.10 molar equivalent of salicylaldehyde, L-lysine racemization can be completed within 4 h in 1.0 mol/L of NaOH at 100°C. The activation energy of the processes was 62187.86 J/mol. The characteristics of AS1.1009 decarboxylase were studied. Under the conditions of pH 8.0, temperature 37°C, cell concentration 10 g/L, tween-80 0.5 g/L, substrate concentration 30 g/L, and the specific activity of up to 3840 U, L-lysine can be completely degraded by the decarboxylase for 12 h under the optimal conditions.

关键词： substrate temperature specific activity presence decarboxylase

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Efficient acetoin production from pyruvate by engineered whole-cell biocatalysis

《化学科学与工程前沿（英文）》 2023年第17卷第4期页码 425-436 doi: 10.1007/s11705-022-2229-0

摘要： Acetoin is an important platform chemical, which has a wide range of applications in many industries. Halomonas bluephagenesis, a chassis for next generation of industrial biotechnology, has advantages of fast growth and high tolerance to organic acid salts and alkaline environment. Here, α-acetolactate synthase and α-acetolactate decarboxylase from Bacillus subtilis 168 were co-expressed in H. bluephagenesis to produce acetoin from pyruvate. After reaction condition optimization and further increase of α-acetolactate decarboxylase expression, acetoin production and yield were significantly enhanced to 223.4 mmol·L^–1 and 0.491 mol·mol^–1 from 125.4 mmol·L^–1 and 0.333 mol·mol^–1, respectively. Finally, the highest titer of 974.3 mmol·L^–1 (85.84 g·L^–1) of acetoin was accumulated from 2143.4 mmol·L^–1 (188.6 g·L^–1) of pyruvic acid within 8 h in fed-batch bioconversion under optimal reaction conditions. Moreover, the reusability of the cell catalysis was also tested, and the result illustrated that the whole-cell catalysis obtained 433.3, 440.2, 379.0, 442.8 and 339.4 mmol·L^–1 (38.2, 38.8, 33.4, 39.0 and 29.9 g·L^–1) acetoin in five repeated cycles under the same conditions. This work therefore provided an efficient H. bluephagenesis whole-cell catalysis with a broad development prospect in biosynthesis of acetoin.

关键词： acetoin pyruvate α-acetolactate synthetase α-acetolactate decarboxylase Halomonas bluephagenesis whole-cell biocatalysis