Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8565, Japan.
Sumitomo Forestry Co., LTD., 3-2 Midorigahara, Tsukuba, Ibaraki, 300-2646, Japan.
Appl Microbiol Biotechnol. 2021 Sep;105(18):6679-6689. doi: 10.1007/s00253-021-11508-3. Epub 2021 Aug 30.
A series of culture media for haloarchaea were evaluated to optimize the production of ultrahigh-molecular-weight (UHMW) poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by Haloferax mediterranei. Cells of H. mediterranei grew (> 1 g/L of dry cell weight) and accumulated PHBV upon flask cultivation in 10 medium types with neutral pH and NaCl concentration > 100 g/L. Molecular weight and compositional analysis revealed that the number-average molecular weight (M) of PHBV produced with six selected types of media ranged from 0.8 to 3.5 × 10 g/mol and the 3-hydroxyvalerate (3HV) composition ranged from 8 to 36 mol%. Cultivation in two NBRC media, 1214 and 1380, resulted in the production of PHBV with an M of more than 3.0 × 10 g/mol and a weight-average molecular weight of more than 5.0 × 10 g/mol, indicating the production of UHMW-PHBV. These culture media contained small amount of complex nutrients like yeast extract and casamino acids, suggesting that H. mediterranei likely produced UHMW-PHBV on poor nutrient condition. Haloferax mediterranei grown in NBRC medium 1380 produced PHBV with the highest 3HV composition. A solvent-cast film of UHMW-PHBV with 26.4 mol% 3HV produced from 1-L flask cultivation with NBRC medium 1380 was found to be flexible and semi-transparent. Thermal analysis of the UHMW-PHBV cast film revealed melting and glass-transition temperatures of 90.5 °C and - 2.7 °C, respectively. KEY POINTS: • Haloarchaeal culture media were evaluated to produce UHMW-PHBV by H. mediterranei. • UHMW-PHBV with varied molecular weight was produced dependent on culture media. • Semi-transparent film could be made from UHMW-PHBV with 26.4 mol% 3HV.
为了优化地中海盐杆菌生产超高相对分子质量（UHMW）聚（3-羟基丁酸-co-3-羟基戊酸）（PHBV），对一系列嗜盐古菌培养基进行了评估。在 pH 值中性、NaCl 浓度>100g/L 的 10 种培养基中进行摇瓶培养时，地中海盐杆菌细胞生长（>1g/L 干细胞重量）并积累 PHBV。分子量和组成分析表明，用 6 种选定类型的培养基生产的 PHBV 的数均分子量（M）范围为 0.8 至 3.5×10g/mol，3-羟基戊酸（3HV）组成范围为 8 至 36mol%。在 NBRC 培养基 1214 和 1380 中培养导致 PHBV 的 M 超过 3.0×10g/mol，重均分子量超过 5.0×10g/mol，表明生产了 UHMW-PHBV。这些培养基含有少量复杂的营养物质，如酵母提取物和水解酪蛋白，这表明地中海盐杆菌可能在营养较差的情况下生产 UHMW-PHBV。在 NBRC 培养基 1380 中生长的地中海盐杆菌产生的 PHBV 3HV 组成最高。从 1-L 摇瓶培养中用 NBRC 培养基 1380 生产的 UHMW-PHBV 的 26.4mol%3HV 的溶剂浇铸膜发现是柔韧和半透明的。UHMW-PHBV 铸膜的热分析显示出 90.5°C 的熔融和-2.7°C 的玻璃化转变温度。关键点： • 评估了嗜盐古菌培养基以生产 H. mediterranei 的 UHMW-PHBV。 • 依赖于培养基生产了具有不同分子量的 UHMW-PHBV。 • 可以从具有 26.4mol%3HV 的 UHMW-PHBV 制成半透明膜。
