Environmental Sampling and Storage (extracted from Hatzenpichler et. al., 2016)
R/V Atlantis cruise AT-15-68:
Sediment sample #3730 was obtained from Hydrate Ridge South methane seep field (Alvin Dive 4635; push-core 16; 44 deg 34.09 N,125 deg 9.14 W; 775 m water depth; sediment horizon 0–6 cm; 4C in-situ temperature) on 7 August 2010. Sediment was stored underargon headspace in a Mylar bag for 5 wk before being transferred toa 1-L glass bottle with a 1.38 bar 100% methane headspace, which was stored at 4C for ~4 years. Seawater and headspace were exchanged at regular intervals to prevent the accumulation of inhibitory compounds.
MBARI Cruise 2013 "Southern California"
Sediment sample #7142 was collected from Santa Monica Basinon 7 May 2013 (R/V Western Flyer MBARI Cruise 2013; dive 459; push-core 74; 33 deg 47.34 N, 118 deg 40.09 W; 863 m depth; sedimenthorizon 4–6 cm; 4C in situ temperature). The sediment was sealed under argon and stored at 4C. After 40 days of storage, the sediment was suspended in anaerobic natural bottom seawater from the site in an anaerobic chamber (3% H2 in N2) and aliquots were overpressured with 1.5 bar methane. The sediment was kept for 12 months under 1.5 bar 100% methane in natural bottom seawater that was exchanged every 3 mo.
All Sample Handling:
All samples were kept in an ice bath at all times during handling. Artificial seawater (ASW) consisted of 10.9 g of MgCl2·6H2O, 0.2 g of NaHCO3, 0.76 g ofKCl, 25.9 g ofNaCl, 1.47 g of CaCl2·2H2O, 3.98 g of Na2SO4, and 26.73 mg of NH4Cl per liter of ddH2O at pH 7.4. One milliliter of vitamin solution (see medium 141, https://www.dsmz.de) and 1 mL of trace element solution SL- 10 (see https://www.dsmz.de) were also added. Before use, ASW was filtered through a 0.2-μm filter and N2-bubbled for 10 min. ASW was kept on ice during handling. For more information on resuspension and incubation procedures used see Hatzenpichler et. al., 2016.