Table_1_Improved Salt Tolerance and Metabolomics Analysis of Synechococcus elongatus UTEX 2973 by Overexpressing Mrp Antiporters.DOCX

The fast-growing cyanobacterium Synechococcus elongatus UTEX 2973 (Syn2973) is a promising candidate for photosynthetic microbial factory. Seawater utilization is necessary for large-scale cultivation of Syn2973 in the future. However, Syn2973 is sensitive to salt stress, making it necessary to improve its salt tolerance. In this study, 21 exogenous putative transporters were individually overexpressed in Syn2973 to evaluate their effects on salt tolerance. The results showed the overexpression of three Mrp antiporters significantly improved the salt tolerance of Syn2973. Notably, overexpressing the Mrp antiporter from Synechococcus sp. PCC 7002 improved cell growth by 57.7% under 0.4 M NaCl condition. In addition, the metabolomics and biomass composition analyses revealed the possible mechanisms against salt stress in both Syn2973 and the genetically engineered strain. The study provides important engineering strategies to improve salt tolerance of Syn2973 and is valuable for understanding mechanisms of salt tolerance in cyanobacteria.

快速增长蓝藻Synechococcus elongatus UTEX 2973（Syn2973）作为一种具有潜力的光合微生物工厂候选者，备受关注。鉴于未来大规模培养Syn2973的需求，海水利用成为必要条件。然而，Syn2973对盐胁迫敏感，因此提升其耐盐性至关重要。在本研究中，通过单独在Syn2973中过表达21个外源假定的转运蛋白，以评估其对耐盐性的影响。研究结果显示，过表达三种Mrp反向转运蛋白显著增强了Syn2973的耐盐性。尤为显著的是，从Synechococcus sp. PCC 7002中过表达的Mrp反向转运蛋白在0.4 M NaCl条件下，将细胞生长提高了57.7%。此外，通过代谢组学和生物量组成分析，揭示了Syn2973和基因工程菌株对抗盐胁迫的可能机制。该研究为提升Syn2973耐盐性提供了重要的工程策略，并对理解蓝藻耐盐机制具有重要意义。