Microbial communities from Arctic marine sedimentsrespond slowly to methane addition duringex situenrichments

• Published in: Environmental Microbiology
• Main Authors: Klasek, Scott, Torres, Martha, Bartlett, Douglas H., Tyler, Madeline, Hong, Wei-Li, Colwell, Frederick
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: VDP::Mathematics and natural science: 400; VDP::Matematikk og Naturvitenskap: 400; Arctic; Svalbard
• Online Access: https://hdl.handle.net/10037/18375; https://doi.org/10.1111/1462-2920.14895

This is the peer reviewed version of the following article: Klasek, S., Torres, M. E., Bartlett, D. H., Tyler, M., Hong, W.-L. & Colwell, F. (2019). Microbial communities from Arctic marine sediments respond slowly to methane addition during ex situ enrichments. Environmental Microbiology, 22 (5), 1829-1846, which has been published in final form at https://doi.org/10.1111/1462-2920.14895 . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. Anaerobic methanotrophic archaea (ANME) consume methane in marine sediments, limiting its release to the water column, but their responses to changes in methane and sulfate supplies remain poorly constrained. To address how methane exposure may affect microbial communities and methane‐ and sulfur‐cycling gene abundances in Arctic marine sediments, we collected sediments from offshore Svalbard that represent geochemical horizons where anaerobic methanotrophy is expected to be active, previously active, and long‐inactive based on reaction‐transport biogeochemical modelling of porewater sulfate profiles. Sediment slurries were incubated at in situ temperature and pressure with different added methane concentrations. Sediments from an active area of seepage began to reduce sulfate in a methane‐dependent manner within months, preceding increased relative abundances of anaerobic methanotrophs ANME‐1 within communities. In previously active and long‐inactive sediments, sulfur‐cycling Deltaproteobacteria became more dominant after 30 days, though these communities showed no evidence of methanotrophy after nearly 8 months of enrichment. Overall, enrichment conditions, but not methane, broadly altered microbial community structure across different enrichment times and sediment types. These results suggest that active ANME populations may require years to develop, and consequently microbial community composition may affect methanotrophic responses to potential large‐scale seafloor methane releases in ways that provide insight for future modelling studies.