Digital Health Laboratory, Nokia Technologies , Karaportti 4, FI-02610 Espoo, Finland.
ACS Appl Mater Interfaces. 2017 Jun 7;9(22):19048-19056. doi: 10.1021/acsami.7b04927. Epub 2017 May 30.
Some bacterial strains such as Komagataeibacter xylinus are able to produce cellulose as an extracellular matrix. In comparison to wood-based cellulose, bacterial cellulose (BC) holds interesting properties such as biodegradability, high purity, water-holding capacity, and superior mechanical and structural properties. Aiming toward improvement in BC production titer and tailored alterations to the BC film, we engineered K. xylinus to overexpress partial and complete bacterial cellulose synthase operon that encodes activities for BC production. The changes in cell growth, end metabolite, and BC production titers from the engineered strains were compared with the wild-type K. xylinus. Although there were no significant differences between the growth of wild-type and engineered strains, the engineered K. xylinus strains demonstrated faster BC production, generating 2-4-fold higher production titer (the highest observed titer was obtained with K. xylinus-bcsABCD strain producing 4.3 ± 0.46 g/L BC in 4 days). The mechanical and structural characteristics of cellulose produced from the wild-type and engineered K. xylinus strains were analyzed with a stylus profilometer, in-house built tensile strength measurement system, a scanning electron microscope, and an X-ray diffractometer. Results from the profilometer indicated that the engineered K. xylinus strains produced thicker BC films (wild type, 5.1 μm, and engineered K. xylinus strains, 6.2-10.2 μm). Scanning electron microscope revealed no principal differences in the structure of the different type BC films. The crystallinity index of all films was high (from 88.6 to 97.5%). All BC films showed significant piezoelectric response (5.0-20 pC/N), indicating BC as a promising sensor material.
一些细菌菌株，如 Komagataeibacter xylinus，能够产生纤维素作为细胞外基质。与基于木材的纤维素相比，细菌纤维素（BC）具有可生物降解性、高纯度、持水能力以及更优越的机械和结构性能等有趣特性。为了提高 BC 的产量并对 BC 薄膜进行定制改造，我们对 K. xylinus 进行了工程改造，使其过度表达部分和完整的细菌纤维素合酶操纵子，该操纵子编码了 BC 生产的活性。对工程菌株的细胞生长、末端代谢物和 BC 生产滴度的变化与野生型 K. xylinus 进行了比较。尽管野生型和工程菌株的生长没有显著差异，但工程 K. xylinus 菌株表现出更快的 BC 生产速度，产生的产量提高了 2-4 倍（观察到的最高产量是 K. xylinus-bcsABCD 菌株在 4 天内产生的 4.3±0.46 g/L BC）。使用触针轮廓仪、内部构建的拉伸强度测量系统、扫描电子显微镜和 X 射线衍射仪对野生型和工程 K. xylinus 菌株产生的纤维素的机械和结构特性进行了分析。轮廓仪的结果表明，工程 K. xylinus 菌株产生的 BC 膜更厚（野生型为 5.1μm，工程 K. xylinus 菌株为 6.2-10.2μm）。扫描电子显微镜显示不同类型的 BC 膜的结构没有主要差异。所有薄膜的结晶度指数都很高（88.6-97.5%）。所有 BC 薄膜都表现出显著的压电响应（5.0-20 pC/N），表明 BC 是一种很有前途的传感器材料。
