Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China.
Tianjin Changlu Hangu Saltern Co., LTD, 300480, China.
J Adv Res. 2024 Jun;60:111-125. doi: 10.1016/j.jare.2023.08.004. Epub 2023 Aug 17.
The level of atmospheric CO has continuously been increasing and the resulting greenhouse effects are receiving attention globally. Carbon removal from the atmosphere occurs naturally in various ecosystems. Among them, saline environments contribute significantly to the global carbon cycle. Carbonate deposits in the sediments of salt lakes are omnipresent, and the biological effects, especially driven by halophilic microalgae and bacteria, on carbonate formation remain to be elucidated.
The present study aims to characterize the carbonates formed in saline environments and demonstrate the mechanisms underlying biological-driven CO removal via microalgal-bacterial consortium.
The carbonates naturally formed in saline environments were collected and analyzed. Two saline representative organisms, the photosynthetic microalga Dunaliella salina and its mutualistic halophilic bacteria Nesterenkonia sp. were isolated from the inhabiting saline environment and co-cultivated to study their biological effects on carbonates precipitation and isotopic composition. During this process, electrochemical parameters and Ca flux, and expression of genes related to CaCO formation were analyzed. Genome sequencing and metagenomic analysis were conducted to provide molecular evidence.
The results showed that natural saline sediments are enriched with CaCO and enrichment of genes related to photosynthesis and ureolysis. The co-cultivation stimulated 54.54% increase in CaCO precipitation and significantly promoted the absorption of external CO by 49.63%. A pH gradient was formed between the bacteria and algae culture, creating 150.22 mV of electronic potential, which might promote Ca movement toward D. salina cells. Based on the results of lab-scale induction and C analysis, a theoretical calculation indicates a non-negligible amount of 0.16 and 2.3 Tg C/year carbon sequestration in China and global saline lakes, respectively.
The combined effects of these two typical representative species have contributed to the carbon sequestration in saline environments, by promoting Ca influx and increase of pH via microalgal and bacterial metabolic processes.
大气中 CO 的水平持续上升，由此产生的温室效应引起了全球关注。大气中的碳自然地在各种生态系统中被去除。其中，盐环境对全球碳循环有重要贡献。盐湖沉积物中的碳酸盐无处不在，而由嗜盐微生物驱动的碳酸盐形成的生物效应仍有待阐明。
本研究旨在描述盐环境中形成的碳酸盐，并展示微藻-细菌共生体通过生物驱动去除 CO 的机制。
采集了盐环境中自然形成的碳酸盐，并进行了分析。从栖息的盐环境中分离出光合微藻杜氏盐藻和其共生的嗜盐菌 Nesterenkonia sp.，并进行共培养，以研究它们对碳酸盐沉淀和同位素组成的生物效应。在此过程中，分析了电化学参数和 Ca 通量以及与 CaCO 形成相关的基因表达。进行了基因组测序和宏基因组分析，以提供分子证据。
结果表明，自然盐沉积物富含 CaCO ，并富集了与光合作用和脲解相关的基因。共培养刺激了 54.54%的 CaCO 沉淀增加，并显著促进了外部 CO 的吸收，增加了 49.63%。细菌和藻类培养之间形成了 pH 梯度，产生了 150.22 mV 的电子势，这可能促进了 Ca 向 D. salina 细胞的移动。根据实验室规模的诱导和 C 分析结果，理论计算表明，中国和全球盐湖的盐环境每年分别有 0.16 和 2.3 Tg C 的碳固存量不可忽视。
这两种典型代表物种的综合作用促进了盐环境中的碳固存，通过微藻和细菌代谢过程促进 Ca 流入和 pH 升高。
