Microbial consumption of zero‐valence sulfur in marine benthic habitats

Summary Zero‐valence sulfur ( S 0 ) is a central intermediate in the marine sulfur cycle and forms conspicuous accumulations at sediment surfaces, hydrothermal vents and in oxygen minimum zones. Diverse microorganisms can utilize S 0 , but those consuming S 0 in the environment are largely unknown. We identified possible key players in S 0 turnover on native or introduced S 0 in benthic coastal and deep‐sea habitats using the 16 S ribosomal RNA approach, ( in situ ) growth experiments and activity measurements. In all habitats, the epsilonproteobacterial S ulfurimonas/ S ulfurovum group accounted for a substantial fraction of the microbial community. Deltaproteobacterial D esulfobulbaceae and D esulfuromonadales were also frequently detected, indicating S 0 disproportionation and S 0 respiration under anoxic conditions. Sulfate production from S 0 particles colonized in situ with S ulfurimonas/ S ulfurovum suggested that this group oxidized S 0 . We also show that the type strain S ulfurimonas denitrificans is able to access cyclooctasulfur ( S 8 ), a metabolic feature not yet demonstrated for sulfur oxidizers. The ability to oxidize S 0 , in particular S 8 , likely facilitates niche partitioning among sulfur oxidizers in habitats with intense microbial sulfur cycling such as sulfidic sediment surfaces. Our results underscore the previously overlooked but central role of S ulfurimonas / S ulfurovum group for conversion of free S 0 at the seafloor surface.