biostudies-literatureGuo RNatural Environmental Research Council, UKShandong Provincial Natural Science FoundationChina Scholarship CouncilPostdoctoral Research Foundation of ChinaNatural Science Foundation of Shandong ProvinceNational Natural Science Foundation of ChinaPostdoctoral Innovation Project of Shandong ProvinceNational Key Research and Development Program of ChinaBiotechnology and Biological Sciences Research Councile10141https://www.ebi.ac.uk/biostudies/studies/S-EPMC12904073biostudies-literatureUnknown13(9)Hydrogen sulfide (H₂S), methanethiol (MeSH), and dimethylsulfide (DMS) are abundant sulfur gases with crucial roles in global sulfur cycling, chemotaxis, and climate regulation. Microorganisms can S-methylate H₂S and MeSH, which can be cytotoxic, to yield non-toxic DMS via MddA or MddH enzymes in largely terrestrial or marine environments, respectively. However, the potential of many important and abundant bacteria like Actinomycetota is underestimated due to unknown Mdd enzymes. Here, two novel S-adenosine-methionine-dependent H₂S and MeSH S-methyltransferases, MddM1 and MddM2 are identified, in the DMS-producing actinomycete Mycolicibacterium poriferae (M. poriferae) ZYF656, isolated from the Mariana Trench. M. poriferae ZYF656 MddM1 and MddM2 likely detoAdvanced science (Weinheim, Baden-Wurttemberg, Germany)Two Novel S-methyltransferases Confer Dimethylsulfide Production in Actinomycetota.PMC129040732025YFF05169004237610132370118423061152022M722975SDCX-ZG-202201016NE/P012671SDCX‐ZG‐202201016ZR2023QD017BB/X0059682025YFF0516903202106330012Devine RZhang XHZheng YGuo ZZhang YSun CGates AJLiu RTodd JDGuo RZhou YCheng HfalseTwo Novel S-methyltransferases Confer Dimethylsulfide Production in Actinomycetota.Hydrogen sulfide (H₂S), methanethiol (MeSH), and dimethylsulfide (DMS) are abundant sulfur gases with crucial roles in global sulfur cycling, chemotaxis, and climate regulation. Microorganisms can S-methylate H₂S and MeSH, which can be cytotoxic, to yield non-toxic DMS via MddA or MddH enzymes in largely terrestrial or marine environments, respectively. However, the potential of many important and abundant bacteria like Actinomycetota is underestimated due to unknown Mdd enzymes. Here, two novel S-adenosine-methionine-dependent H₂S and MeSH S-methyltransferases, MddM1 and MddM2 are identified, in the DMS-producing actinomycete Mycolicibacterium poriferae (M. poriferae) ZYF656, isolated from the Mariana Trench. M. poriferae ZYF656 MddM1 and MddM2 likely deto2026-01-01T00:00:00Z2026 Feb2026-07-15T22:02:20.798Z2026-07-09T13:09:29.958ZS-EPMC129040734133231810.1002/advs.202510141