Kleindienst Sara, Polerecky Lubos, Amann Rudolf, Musat Florin, Knittel Katrin
Max Planck Institute for Marine Microbiology, Bremen, Germany.
Department of Environmental Microbiology, Institute for Sanitary Engineering, Water Quality and Solid Waste Management (ISWA), University of Stuttgart, Stuttgart, Germany.
Environ Microbiol. 2025 Aug;27(8):e70151. doi: 10.1111/1462-2920.70151.
Marine hydrocarbon seeps are hotspots for sulphate reduction coupled to hydrocarbon oxidation. In situ metabolic rates of sulphate-reducing bacteria (SRB) degrading hydrocarbons other than methane, however, remain poorly understood. Here, we assessed the environmental role of Desulfosarcinaceae clades SCA1, SCA2 for degradation of n-butane and clade LCA2 for n-dodecane. Quantification by CARD-FISH showed that SCA1 constituted up to 31%, SCA2 up to 9%, and LCA2 up to 6% of cells from the recently re-classified class Deltaproteobacteria across diverse hydrocarbon seeps. Cell-specific oxidation rates estimated by stable-isotope probing combined with NanoSIMS and modelling were ~0.73 and ~2.11 fmol butane cell d for SCA1 and SCA2, respectively, and ~0.023 fmol dodecane cell d for LCA2 in sediments from Amon Mud Volcano and Guaymas Basin sediments. Cellular carbon assimilation, dissolved inorganic carbon production, and sulphate reduction rates indicated that butane-degrading SRB have higher metabolic activity than those utilising dodecane. Estimates based on in situ cell abundances, biovolumes, and cellular activities suggest that at certain seeps, clades SCA1, SCA2 and LCA2 account for nearly all sulphate reduction not driven by methane oxidation. These findings highlight the important role of alkane-degrading SRB in influencing marine carbon and sulphur cycles, particularly at seeps emitting higher hydrocarbons.
海洋碳氢化合物渗漏区是硫酸盐还原与碳氢化合物氧化耦合的热点区域。然而，除甲烷之外，降解碳氢化合物的硫酸盐还原菌（SRB）的原位代谢速率仍鲜为人知。在此，我们评估了脱硫八叠球菌科进化枝SCA1、SCA2对正丁烷的降解作用以及进化枝LCA2对正十二烷的降解作用。通过催化报告沉积荧光原位杂交（CARD-FISH）进行定量分析表明，在最近重新分类的δ变形菌纲中，来自不同碳氢化合物渗漏区的细胞中，SCA1占比高达31%，SCA2占比高达9%，LCA2占比高达6%。在阿蒙泥火山和瓜伊马斯海盆沉积物中，通过稳定同位素示踪结合纳米二次离子质谱（NanoSIMS）和建模估算的细胞特异性氧化速率显示，SCA1和SCA2对正丁烷的氧化速率分别约为0.73和2.11飞摩尔/细胞·天，LCA2对正十二烷的氧化速率约为0.023飞摩尔/细胞·天。细胞碳同化、溶解无机碳生成和硫酸盐还原速率表明，降解正丁烷的SRB比利用正十二烷的SRB具有更高的代谢活性。基于原位细胞丰度、生物体积和细胞活性的估算表明，在某些渗漏区，进化枝SCA1、SCA2和LCA2几乎占所有非甲烷氧化驱动的硫酸盐还原作用。这些发现突出了降解烷烃的SRB在影响海洋碳和硫循环中的重要作用，特别是在排放高碳氢化合物的渗漏区。
