Lehrgebiet Bioverfahrenstechnik, Technische Universität Kaiserslautern, Gottlieb-Daimler-Straße 49, 67663 Kaiserslautern, Germany.
Abteilung für Mikrobiologie, Technische Universität Kaiserslautern, Erwin-Schroedinger-Straße 56, 67663 Kaiserslautern, Germany.
J Biotechnol. 2018 May 20;274:47-53. doi: 10.1016/j.jbiotec.2018.03.006. Epub 2018 Mar 13.
Phycoerythrobilin (PEB) is an open-chain tetrapyrrole derived from heme and plays an important role as light-harvesting pigment in the phycobiliproteins of cyanobacteria and red algae. Furthermore, PEB can also function as an antioxidant with potential use as a natural acid stable food colorant. PEB is not commercially available and large, pure quantities can only be obtained by laborious methanolysis of red algae followed by liquid chromatography. Here we describe an improved method for high yield production and purification of PEB in Escherichia coli via heterologous expression where the two required enzymes heme oxygenase and PEB synthase subsequently convert the substrate heme provided by the host cell. Experiments in shaking flasks resulted in the highest product yield of 680.23 ± 42.75 μg PEB per g cell dry weight, by induction with 0.1 mM IPTG. Scale-up to batch-operated fermentation in a 2 L bioreactor reached product concentrations up to 5.02 mg PEB L by adjustment of aeration, induction time, media composition and supplementation of precursors. A further approach included separation of PEB from developed foam above the culture. This enabled continuous product collection during cultivation and simplified product purification. Produced PEB was validated via UV-vis spectroscopy, high pressure liquid chromatography and mass spectrometry.
藻红胆素(PEB)是一种开链四吡咯,来源于血红素,在蓝藻和红藻的藻胆蛋白中作为光捕获色素发挥重要作用。此外,PEB 还可以作为一种抗氧化剂,具有作为天然酸稳定食用色素的潜在用途。PEB 目前没有商业化供应,只能通过繁琐的甲醇解法从红藻中提取,然后进行液相色谱分离,才能获得大量纯净的 PEB。本研究描述了一种通过异源表达在大肠杆菌中高效生产和纯化 PEB 的改良方法,其中两种所需的酶血红素加氧酶和 PEB 合酶随后将宿主细胞提供的底物血红素转化为 PEB。在摇瓶实验中,通过 0.1mM IPTG 诱导,获得了最高 680.23±42.75μg PEB/g 细胞干重的产物产率。放大到 2L 生物反应器中的分批操作发酵,通过调整通气、诱导时间、培养基组成和前体补充,产物浓度可达到 5.02mg PEB/L。进一步的方法包括从培养物上方形成的泡沫中分离 PEB。这使得在培养过程中能够连续收集产物,并简化产物纯化。通过紫外可见光谱、高效液相色谱和质谱对所产生的 PEB 进行了验证。