Zero-valent sulfur (ZVS) has been shown to be a major sulfur intermediate in the deep-sea cold seep of the South China Sea based on our previous work, however, the microbial contribution to the formation of ZVS in cold seep has remained unclear. Here, we describe a novel thiosulfate oxidation pathway discovered in the deep-sea cold seep bacterium Erythrobacter flavus 21–3, which provides a new clue about the formation of ZVS. Electronic microscopy, energy-dispersive, and Raman spectra were used to confirm that E. flavus 21–3 effectively converts thiosulfate to ZVS. We next used a combined proteomic and genetic method to identify thiosulfate dehydrogenase (TsdA) and thiosulfohydrolase (SoxB) playing key roles in the conversion of thiosulfate to ZVS. Stoichiometric results of different sulfur intermediates further clarify the function of TsdA in converting thiosulfate to tetrathionate (⁻O₃S–S–S–SO₃⁻), SoxB in liberating sulfone from tetrathionate to form ZVS and sulfur dioxygenases (SdoA/SdoB) in oxidizing ZVS to sulfite under some conditions. Notably, homologs of TsdA, SoxB, and SdoA/SdoB widely exist across the bacteria including in Erythrobacter species derived from different environments. This strongly indicates that this novel thiosulfate oxidation pathway might be frequently used by microbes and plays an important role in the biogeochemical sulfur cycle in nature.

根据我们先前的工作，零价硫（ZVS）已被证明是南海深海冷渗中的主要硫中间产物，但是，微生物对冷渗中ZVS形成的贡献仍不清楚。在这里，我们描述了一种在深海冷渗性细菌淡红细菌21-3中发现的新型硫代硫酸盐氧化途径，它为ZVS的形成提供了新线索。电子显微镜，能量色散和拉曼光谱用于确认黄曲霉21–3有效地将硫代硫酸盐转化为ZVS。接下来，我们使用蛋白质组学和遗传学相结合的方法来鉴定硫代硫酸盐脱氢酶（TsdA）和硫代硫酸盐水解酶（SoxB）在硫代硫酸盐向ZVS的转化中起关键作用。不同硫中间体的化学计量结果进一步阐明TSDA的函数在转换硫代到连四硫酸盐（^- ö ₃ S-S-S-SO ₃ ^- ），SOXB在从连四解放砜以形成ZVS和硫双加氧酶（SDOA / SDOB）在某些条件下将ZVS氧化为亚硫酸盐。值得注意的是，TsdA，SoxB和SdoA / SdoB的同源物广泛存在于整个细菌中，包括在红细菌中来自不同环境的物种。这有力地表明，这种新颖的硫代硫酸盐氧化途径可能被微生物经常使用，并且在自然界中的生物地球化学硫循环中起着重要作用。