Chen Ching-Nen Nathan, Lin Keng-Min, Lin Yu-Chen, Chang Hsin-Ying, Yong Tze Ching, Chiu Yi-Fang, Kuo Chih-Horng, Chu Hsiu-An
Department of Oceanography, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 115, Taiwan.
BMC Microbiol. 2025 May 8;25(1):279. doi: 10.1186/s12866-025-03993-7.
Cyanobacteria have diversified through their long evolutionary history and occupy a wide range of environments on Earth. To advance our understanding of their adaptation mechanisms in extreme environments, we performed stress tolerance characterizations, whole genome sequencing, and comparative genomic analyses of a novel heat-tolerant and euryhaline strain of the unicellular cyanobacterium Cyanobacterium sp. Dongsha4 (DS4). This strain was isolated from a lagoon on Dongsha Island in the South China Sea, a habitat with fluctuations in temperature, salinity, light intensity, and nutrient supply.
DS4 cells can tolerate long-term high-temperature up to 50 ℃ and salinity from 0 to 6.6%, which is similar to the results previously obtained for Cyanobacterium aponinum. In contrast, most mesophilic cyanobacteria cannot survive under these extreme conditions. Based on the 16S rRNA gene phylogeny, DS4 is most closely related to Cyanobacterium sp. NBRC102756 isolated from Iwojima Island, Japan, and Cyanobacterium sp. MCCB114 isolated from Vypeen Island, India. For comparison with strains that have genomic information available, DS4 is most similar to Cyanobacterium aponinum strain PCC10605 (PCC10605), sharing 81.7% of the genomic segments and 92.9% average nucleotide identity (ANI). Gene content comparisons identified multiple distinct features of DS4. Unlike related strains, DS4 possesses the genes necessary for nitrogen fixation. Other notable genes include those involved in photosynthesis, central metabolisms, cyanobacterial starch metabolisms, stress tolerances, and biosynthesis of novel secondary metabolites.
These findings promote our understanding of the physiology, ecology, evolution, and stress tolerance mechanisms of cyanobacteria. The information is valuable for future functional studies and biotechnology applications of heat-tolerant and euryhaline marine cyanobacteria.
蓝细菌在其漫长的进化历史中实现了多样化，并占据了地球上广泛的环境。为了增进我们对它们在极端环境中适应机制的理解，我们对一种新型耐热且耐盐的单细胞蓝细菌东沙蓝细菌属（Cyanobacterium sp.）董沙4号（DS4）菌株进行了胁迫耐受性表征、全基因组测序和比较基因组分析。该菌株是从中国南海东沙岛的一个泻湖中分离出来的，该栖息地的温度、盐度、光照强度和养分供应存在波动。
DS4细胞能够耐受高达50℃的长期高温以及0%至6.6%的盐度，这与先前对阿波蓝细菌（Cyanobacterium aponinum）获得的结果相似。相比之下，大多数嗜温蓝细菌在这些极端条件下无法存活。基于16S rRNA基因系统发育，DS4与从日本硫磺岛分离的蓝细菌属NBRC102756菌株以及从印度维平岛分离的蓝细菌属MCCB114菌株关系最为密切。为了与具有可用基因组信息的菌株进行比较，DS4与阿波蓝细菌菌株PCC10605（PCC10605）最为相似，共享81.7%的基因组片段和92.9%的平均核苷酸同一性（ANI）。基因含量比较确定了DS4的多个独特特征。与相关菌株不同，DS4拥有固氮所需的基因。其他值得注意的基因包括参与光合作用、中心代谢、蓝细菌淀粉代谢、胁迫耐受性和新型次生代谢物生物合成的基因。
这些发现增进了我们对蓝细菌的生理学、生态学、进化和胁迫耐受机制的理解。这些信息对于耐热且耐盐海洋蓝细菌未来的功能研究和生物技术应用具有重要价值。
