Generation of zero-valent sulfur from dissimilatory sulfate reduction in sulfate-reducing microorganisms
Shanquan Wang, Qihong Lu, Zhiwei Liang, Xiaoxiao Yu, Mang Lin, Bixian Mai, Rongliang Qiu, Wensheng Shu, Zhili He, Judy D. Wall
Abstract
Dissimilatory sulfate reduction (DSR) mediated by sulfate-reducing microorganisms (SRMs) plays a pivotal role in global sulfur, carbon, oxygen, and iron cycles since at least 3.5 billion y ago. The canonical DSR pathway is believed to be sulfate reduction to sulfide. Herein, we report a DSR pathway in phylogenetically diverse SRMs through which zero-valent sulfur (ZVS) is directly generated. We identified that approximately 9% of sulfate reduction was directed toward ZVS with S 8 as a predominant product, and the ratio of sulfate-to-ZVS could be changed with SRMs’ growth conditions, particularly the medium salinity. Further coculturing experiments and metadata analyses revealed that DSR-derived ZVS supported the growth of various ZVS-metabolizing microorganisms, highlighting this pathway as an essential component of the sulfur biogeochemical cycle.