Effect of Storage Conditions on Archaeal and Bacterial Communities in Subsurface Marine Sediments

Abstract

We have studied the effects of slow infiltration of oxygen on microbial communities in refrigerated legacy samples from ocean drilling expeditions. Storage was in heat-sealed, laminated foil bags with a N₂ headspace for geomicrobiological studies. Analysis of microbial lipids suggests that Bacteria were barely detectable in situ but increased remarkably during storage. Detailed molecular examination of a methane-rich sediment horizon showed that refrigeration triggered selective growth of ANME-2 archaea and a drastic change in the bacterial community. Subsequent enrichment targeting methanogens yielded exclusively methylotrophs, which were probably selected for by high sulfate levels caused by oxidation of reduced sulfur species. We provide recommendations for sample storage in future ocean drilling expeditions.

Keywords:

• anaerobic oxidation of methane
• ANME
• deep biosphere
• glycolipid
• intact polar lipid
• mcrA
• ocean drilling
• phospholipid
• 16S rRNA

Samples for this research were provided by the Integrated Ocean Drilling Program (IODP, Expeditions 307 and 311) and the Ocean Drilling Program (ODP, Legs 201, 204 and 207). We thank the participating crews and scientists for sample recovery; Timothy G. Ferdelman for sample donation; Peter Behrend for performing oxygen analysis; Felix Elling, Tanja Hörner and Silvana Pape for assistance with sample preparation and analysis of sulfate concentration; and Brit Kockisch for TOC measurements. This work was funded through DFG-Research Center / Excellence Cluster ‘MARUM - The Ocean in the Earth System’ and by the NSF Ocean Drilling Program grants OCE-0527167 and OCE-0727175 to AT. JFB was funded through a NASA NAI postdoctoral fellowship administered by ORAU.

Notes

†Y.S.L. and J.F.B. contributed equally to this work.

^c Not determined.

*Used for IPL analysis.