Blue light promotes zero-valent sulfur production in a deep-sea bacterium

Bacteria isolated from diverse environments were found to sense blue light to regulate their biological functions. However, this ability of deep-sea bacteria has been studied rarely. In this study, we found serendipitously that blue light stimulated excess zero-valent sulfur (ZVS) production of E. flavus 21-3, which was isolated from the deep-sea cold seep and possessed a novel thiosulfate oxidation pathway. Its ZVS production responding to the blue light was mediated by a light-oxygen-voltage histidine kinase (LOV-1477), a diguanylate cyclase (DGC-2902), a PilZ protein (mPilZ-1753) and the key thiosulfate dehydrogenase (TsdA) in its thiosulfate oxidation pathway. Subsequently, the thiosulfohydrolase (SoxB-277) was found working with another SoxB (SoxB-285) and being as substitute for each other to generate ZVS. This study provided an example of deep-sea bacteria sensing blue light to regulate thiosulfate oxidation. Deep-sea blue light potentially helped these blue-light-sensing bacteria adapt harsh conditions by diversifying their biological processes.