Metabolic and Biomolecular Engineering National Research Laboratory, Systems Metabolic Engineering and Systems Healthcare Cross-Generation Collaborative Laboratory, Department of Chemical and Biomolecular Engineering (BK21 Plus Program), Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon, Republic of Korea.
Applied Science Research Institute, Korea Advanced Institute of Science and Technology (KAIST), Yuseong-gu, Daejeon, Republic of Korea.
Biotechnol Bioeng. 2020 Jul;117(7):2187-2197. doi: 10.1002/bit.27354. Epub 2020 Apr 21.
Poly(d-lactate-co-glycolate-co-4-hydroxybutyrate) [poly(d-LA-co-GA-co-4HB)] and poly(d-lactate-co-glycolate-co-4-hydroxybutyrate-co-d-2-hydroxybutyrate) [poly(d-LA-co-GA-co-4HB-co-d-2HB)] are of interest for their potential applications as new biomedical polymers. Here we report their enhanced production by metabolically engineered Escherichia coli. To examine the polymer properties, poly(d-LA-co-GA-co-4HB) polymers having various monomer compositions (3.4-41.0mol% of 4HB) were produced by culturing the engineered E. coli strain expressing xylBC from Caulobacter crescentus, evolved phaC1 from Pseudomonas sp. MBEL 6-19 (phaC1437), and evolved pct from Clostridium propionicum (pct540) in a medium supplemented with sodium 4HB at various concentrations. To produce these polymers without 4HB feeding, the 4HB biosynthetic pathway was additionally constructed by expressing Clostridium kluyveri sucD and 4hbD. The engineered E. coli expressing xylBC, phaC1437, pct540, sucD, and 4hbD successfully produced poly(d-LA-co-GA-co-4HB-co-d-2HB) and poly(d-LA-co-GA-co-4HB) from glucose and xylose. Through modulating the expression levels of the heterologous genes and performing fed-batch cultures, the polymer content and titer could be increased to 65.76wt% and 6.19g/L, respectively, while the monomer fractions in the polymers could be altered as desired. The polymers produced, in particular, the 4HB-rich polymers showed viscous and sticky properties suggesting that they might be used as medical adhesives.
聚（D-乳酸-共-乙醇酸-共-4-羟基丁酸）[聚（DLLA-co-GA-co-4HB）]和聚（D-乳酸-共-乙醇酸-共-4-羟基丁酸-共-D-2-羟基丁酸）[聚（DLLA-co-GA-co-4HB-co-D-2HB）]因其作为新型生物医学聚合物的潜在应用而受到关注。在这里，我们报告了通过代谢工程大肠杆菌来增强它们的生产。为了研究聚合物的性质，通过培养表达来自新月柄杆菌的 xylBC 的工程化大肠杆菌菌株、来自假单胞菌MBEL 6-19 的进化 phaC1（phaC1437）和来自丙酸梭菌的进化 pct（pct540），在补充有不同浓度的 4HB 的培养基中生产具有各种单体组成（3.4-41.0mol%4HB）的聚（DLLA-co-GA-co-4HB）聚合物。为了在没有 4HB 进料的情况下生产这些聚合物，通过表达克氏梭菌 sucD 和 4hbD 进一步构建了 4HB 生物合成途径。表达 xylBC、phaC1437、pct540、sucD 和 4hbD 的工程化大肠杆菌能够成功地从葡萄糖和木糖生产聚（DLLA-co-GA-co-4HB-co-D-2HB）和聚（DLLA-co-GA-co-4HB）。通过调节异源基因的表达水平并进行分批补料培养，可以将聚合物含量和滴度分别提高到 65.76wt%和 6.19g/L，同时可以按需要改变聚合物中的单体分数。所生产的聚合物，特别是 4HB 丰富的聚合物具有粘性和粘性特性，表明它们可能用作医用粘合剂。
