Liu Daixi, Chen Bokun, Meng Yue, Wang Yafei, Zhao Wei, Ji Hongli, Yang Xue, Zhu Minghao, Zheng Liwen, Li Gang, Liu Jihua
State Key Laboratory of Discovery and Utilization of Functional Components in Traditional Chinese Medicine, Key Laboratory of Chemical Biology (Ministry of Education), Shandong Basic Science Research Center (Pharmacy), School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China.
Institute of Marine Science and Technology, Shandong University, Qingdao, China.
mBio. 2025 Aug 25:e0184425. doi: 10.1128/mbio.01844-25.
a type of picoplankton, plays a crucial role in the carbon (C) and silicon (Si) biogeochemical cycles of the ocean. Their contribution to biological Si within the oligotrophic oceans can be comparable to that of diatoms. However, the mechanisms of Si assimilation, accumulation, and its impact on cellular metabolism in remain poorly understood. Here, we analyzed the physiological and transcriptomic responses of a model strain sp. PCC 7002 in the exponential growth phase to gradient Si enrichment conditions (0, 25, 50, 120, and 200 μmol L) and performed knockouts of Si transport genes and to assess relevant function. Results showed that the specific growth rate over 5 days of cultivation was increased by up to 37% in response to Si enrichment under the concentration of 120 μM, accompanied by the physiological parameters, such as cellular content of biological Si and chlorophyll , as well as elevated rates of photosynthetic O evolution and dark respiration, both of which increased with increasing ambient Si concentration especially on day 1. These changes were corroborated by the transcriptomic analysis. Knockout of the and genes reduced the cellular Si content by ~80% both on days 1 and 5. Additionally, we found that two Si transporters were widespread in 469 sequenced cyanobacterial genomes. This study provides new scientific evidence from physiological and metabolic perspectives on the role of in the marine Si and C cycles, serving as a valuable starting point for exploring the mechanisms of Si metabolism in picoplankton.IMPORTANCEThis work first reveals the silicon uptake in PCC 7002 via two silicon transporters SIT-L and Lsi-L, which are widely distributed in 469 sequenced cyanobacterial genomes. This enhances photosynthesis and respiration, thus promoting cell growth. Our study serves as a valuable starting point for exploring the mechanisms of silicon metabolism in , providing biological evidence to explain the silicon accumulation of cyanobacteria in the oceans.
一种微微型浮游生物，在海洋的碳（C）和硅（Si）生物地球化学循环中起着至关重要的作用。它们对贫营养海洋中生物硅的贡献可与硅藻相媲美。然而，关于硅同化、积累的机制及其对细胞代谢的影响仍知之甚少。在此，我们分析了模式菌株聚球藻属（Synechococcus）sp. PCC 7002在指数生长期对梯度硅富集条件（0、25、50、120和200 μmol/L）的生理和转录组反应，并对硅转运基因SIT-L和Lsi-L进行敲除以评估相关功能。结果表明，在120 μM浓度的硅富集条件下，培养5天的比生长速率提高了37%，同时伴随着生物硅和叶绿素a的细胞含量等生理参数，以及光合放氧速率和暗呼吸速率的升高，这两者均随环境硅浓度的增加而增加，尤其是在第1天。这些变化得到了转录组分析的证实。SIT-L和Lsi-L基因的敲除在第１天和第5天均使细胞硅含量降低了约80%。此外，我们发现两个硅转运蛋白在469个已测序的蓝藻基因组中广泛存在。本研究从生理和代谢角度为聚球藻属在海洋硅和碳循环中的作用提供了新的科学证据，为探索微微型浮游生物硅代谢机制提供了有价值的起点。
重要性
这项工作首次揭示了聚球藻属PCC 7002通过两个硅转运蛋白SIT-L和Lsi-L吸收硅，这两个蛋白广泛分布于469个已测序的蓝藻基因组中。这增强了光合作用和呼吸作用，从而促进细胞生长。我们的研究为探索聚球藻属的硅代谢机制提供了有价值的起点，为解释海洋中蓝藻的硅积累提供了生物学证据。
