Abstract：
Direct interspecies electron transfer (DIET) is essential for maintaining the function and stability of anaerobic microbial consortia. However, only limited natural DIET modes have been identified and DIET engineering remains highly challenging. In this study, an unnatural DIET between Shewanella oneidensis MR-1 (SO, electron donating partner) and Rhodopseudomonas palustris (RP, electron accepting partner) was artificially established by a facile living cell-cell click chemistry strategy. By introducing alkyne- or azide-modified monosaccharides onto the cell outer surface of the target species, precise covalent connections between different species in high proximity were realized through a fast click chemistry reaction. Remarkably, upon covalent connection, outer cell surface C-type cytochromes mediated DIET between SO and RP was achieved and identified, although this was never realized naturally. Moreover, this connection directly shifted the natural H2 mediated interspecies electron transfer (MIET) to DIET between SO and RP, which delivered superior interspecies electron exchange efficiency. Therefore, this work demonstrated a naturally unachievable DIET and an unprecedented MIET shift to DIET accomplished by cell-cell distance engineering, offering an efficient and versatile solution for DIET engineering, which extends our understanding of DIET and opens up new avenues for DIET exploration and applications.
摘要：
直接种间电子转移（DIET）对于维持厌氧微生物聚生体的功能和稳定性至关重要。然而,只有有限的自然饮食模式已被确定和饮食工程仍然极具挑战性。这里,ShewanellaoneidensisMR-1之间的非自然饮食（SO，电子供体伴侣)和沼泽红假单胞菌(RP，电子接受伴侣）是通过一种简便的活细胞-细胞点击化学策略人工建立的。通过将炔烃或叠氮化物修饰的单糖引入目标物种的细胞外表面，通过快速点击化学反应实现了高度接近的不同物种之间的精确共价连接。值得注意的是,在共价连接时，获得并鉴定了外细胞表面C型细胞色素介导的SO和RP之间的DIET，尽管这从未自然实现。此外，这种连接直接将自然H2介导的种间电子转移（MIET）转移到SO和RP之间的DIET，提供了优异的种间电子交换效率。因此,这项工作证明了自然无法实现的饮食和前所未有的MIET转变为通过细胞-细胞距离工程完成的饮食，为DIET工程提供高效和通用的解决方案，这将扩展我们对DIET的理解，并为DIET的探索和应用开辟新的途径。
