College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
Key Laboratory of Marine Environmental and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China.
Water Res. 2024 Oct 1;263:122153. doi: 10.1016/j.watres.2024.122153. Epub 2024 Jul 26.
The application of the fermentative bacteria and microalgae coupling system in the wastewater treatment has been studied, but there remains few knowledge regarding the organic and inorganic carbon metabolism within this system. In this study, the carbon metabolism of microalgae and fermentative bacteria was elucidated by C stable isotope labeling and functional gene prediction, respectively. The C glucose and C NaHCO were used as stable isotope tracers to clarify the organic and inorganic carbon metabolism of microalgae, indicating that approximately 71.5 % of the Acetyl-CoA in microalgae was synthesized from organic carbon sources, while 26.8 % was synthesized through the utilization of inorganic carbon sources. Inorganic carbon sources can enhance the activity of photosynthetic system and facilitate the Calvin cycle. Considering the adequate organic carbon sources and insufficient inorganic carbon sources in the fermentative bacteria and microalgae coupling system, NaHCO was added to improve carbon utilization of microalgae. The maximum microalgal lipid yield reached 1130.37 mg/L with 1000 mg/L NaHCO supplementation. Functional gene prediction was used to analysis the effect of various carbon composition on the bacterial carbon metabolism. Notably, the additional inorganic carbon sources increased the abundance of bacterial functional genes associated with the fermentation and acetic acids synthesis, which was advantageous for VFAs production and further promoted microalgae growth. This study can gain a deeper understanding of microbial metabolic mechanisms during the operation of fermentative bacteria and microalgae system, and improve its sustained operational stability.
已研究发酵细菌和微藻耦合系统在废水处理中的应用，但对于该系统中有机和无机碳代谢的知识仍然有限。在这项研究中，通过 C 稳定同位素标记和功能基因预测分别阐明了微藻和发酵细菌的碳代谢。使用 C 葡萄糖和 C NaHCO3 作为稳定同位素示踪剂，阐明了微藻的有机和无机碳代谢，表明微藻中约 71.5%的乙酰辅酶 A 是由有机碳源合成的，而 26.8%是通过利用无机碳源合成的。无机碳源可以增强光合作用系统的活性，促进卡尔文循环。考虑到发酵细菌和微藻耦合系统中有机碳源充足而无机碳源不足，添加了 NaHCO3 以提高微藻的碳利用效率。在添加 1000mg/L NaHCO3 后，微藻的最大脂质产量达到 1130.37mg/L。功能基因预测用于分析不同碳组成对细菌碳代谢的影响。值得注意的是，额外的无机碳源增加了与发酵和乙酸合成相关的细菌功能基因的丰度，有利于 VFAs 的产生，进一步促进了微藻的生长。本研究可以更深入地了解发酵细菌和微藻系统运行过程中的微生物代谢机制，并提高其持续运行的稳定性。
