Competence Center Algal Biotechnology, Department of Applied Biosciences and Process Engineering, Anhalt University of Applied Sciences, Bernburger Strasse 55, 06366 Koethen, Germany.
Institute of Bioanalysis, Coburg University of Applied Sciences and Arts, Friedrich-Streib-Str. 2, 96450 Coburg, Germany.
Biomolecules. 2022 Mar 26;12(4):504. doi: 10.3390/biom12040504.
Cyanobacteria are a promising source for the sustainable production of biodegradable bioplastics such as poly(3-hydroxybutyrate) (PHB). The auto-phototrophic biomass formation is based on light and CO, which is an advantage compared to heterotrophic PHB-producing systems. So far, only a handful of cyanobacterial species suitable for the high-yield synthesis of PHB have been reported. In the present study, the PHB formation, biomass, and elemental composition of sp. NIVA-CYA 255 were investigated. Therefore, a three-stage cultivation process was applied, consisting of a growth stage; an N-, P-, and NP-depleted phototrophic stage; and a subsequent mixotrophic deficiency stage, initiated by sodium acetate supplementation. The extracted cyanobacterial PHB was confirmed by FTIR- and GC-MS analyses. Furthermore, the fluorescent dyes LipidGreen2 and Nile red were used for fluorescence-based monitoring and the visualization of PHB. LipidGreen2 was well suited for PHB quantification, while the application of Nile red was limited by fluorescence emission crosstalk with phycocyanin. The highest PHB yields were detected in NP- (325 mg g) and N-deficiency (213 mg g). The glycogen pool was reduced in all cultures during mixotrophy, while lipid composition was not affected. The highest glycogen yield was formed under N-deficiency (217 mg g). Due to the high carbon storage capacity and PHB formation, sp. NIVA-CYA 255 is a promising candidate for PHB production. Further work will focus on upscaling to a technical scale and monitoring the formation by LipidGreen2-based fluorometry.
蓝藻是可持续生产可生物降解生物塑料（如聚 3-羟基丁酸酯（PHB））的有前途的来源。自养生物量的形成基于光和 CO，与异养 PHB 生产系统相比，这是一个优势。迄今为止，仅报道了少数几种适合高效合成 PHB 的蓝藻物种。在本研究中，研究了 sp. NIVA-CYA 255 的 PHB 形成、生物量和元素组成。因此，应用了三阶段培养过程，包括生长阶段；N、P 和 NP 耗尽的光养阶段；以及随后的混合营养缺乏阶段，通过补充乙酸钠启动。通过 FTIR 和 GC-MS 分析证实了提取的蓝藻 PHB。此外，荧光染料 LipidGreen2 和尼罗红用于荧光监测和 PHB 的可视化。LipidGreen2 非常适合 PHB 定量，而尼罗红的应用受到藻蓝蛋白荧光发射串扰的限制。NP-（325 mg g）和 N 缺乏（213 mg g）时检测到最高 PHB 产率。在混合营养过程中，所有培养物中的糖原库减少，而脂质组成不受影响。在 N 缺乏时形成最高的糖原产率（217 mg g）。由于高碳储存能力和 PHB 形成能力，sp. NIVA-CYA 255 是 PHB 生产的有前途的候选物。进一步的工作将集中在扩大到技术规模和通过基于 LipidGreen2 的荧光计监测形成。
