Comparison of Archaeal and Bacterial Diversity in

Authors: Olivia U Mason David H Case Thomas H Naehr Raymond W Lee Randal B Thomas Jake V Bailey Victoria J Orphan

Publish Date: 2015/05/07

Volume: 70, Issue: 3, Pages: 766-784

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Abstract

Anaerobic oxidation of methane AOM impacts carbon cycling by acting as a methane sink and by sequestering inorganic carbon via AOMinduced carbonate precipitation These precipitates commonly take the form of carbonate nodules that form within methane seep sediments The timing and sequence of nodule formation within methane seep sediments are not well understood Further the microbial diversity associated with sedimenthosted nodules has not been well characterized and the degree to which nodules reflect the microbial assemblage in surrounding sediments is unknown Here we conducted a comparative study of microbial assemblages in methanederived authigenic carbonate nodules and their host sediments using molecular mineralogical and geochemical methods Analysis of 16S rRNA gene diversity from paired carbonate nodules and sediments revealed that both sample types contained methanotrophic archaea ANME1 and ANME2 and syntrophic sulfatereducing bacteria Desulfobacteraceae and Desulfobulbaceae as well as other microbial community members The combination of geochemical and molecular data from Eel River Basin and Hydrate Ridge suggested that some nodules formed in situ and captured the local sedimenthosted microbial community while other nodules may have been translocated or may represent a record of conditions prior to the contemporary environment Taken together this comparative analysis offers clues to the formation regimes and mechanisms of sedimenthosted carbonate nodulesVO conceived of the study and collected the samples at sea OM processed the samples and optimized DNA extraction as well as TRFLP and clone library analyses DC performed iTAG processing and analyses beta diversity analyses and was the coordinating author of the manuscript TN provided XRD data RL performed the isotopic composition analyses JB provided thin section images and RT performed the pore water geochemical measurements DC OM and VO principally contributed to writing the manuscript Three anonymous reviews provided constructive suggestions to improve the manuscript Elizabeth TrembathReichert Stephanie Connon and Jeff Marlow helped with customization of the Silva115 NR99 database Alexis Pasulka provided helpful discussion regarding ordination and statistical probing of microbial communities Josh Steele also provided discussion on ecological statistics and aided with benchtop lab work Benjamin Harrison helped with TRFLP data interpretation Jeff Marlow provided useful feedback on the manuscript The crew of the R/V Atlantis cruise AT1511 as well as the pilots of DSV Alvin dives AD4249 and 4256 aided in sample recovery at sea Funding for this work was provided by a National Science Foundation grant BIOOCE 0825791 to VO and an early career grant by the United States Department of Energy Office of Biological and Environmental Research DESC0003940 to VO This research was also supported by a grant from the NASA Astrobiology Institute Award NNA13AA92A to VO This is NAILife Underground Publication 009 DC was funded by a National Science Foundation Graduate Research Fellowship

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