Supor polyethersulfone

Surface seawater samples were collected from two bays called Garorim (GR) and Gyeonggi (GI) on the west coast of the Korean Peninsula (Fig 1 and Table A in S1 Appendix) as part of the Korean Long-term Marine Ecological Research Program, which was conducted in April, July, and October of 2015 and in February 2016. The major difference between the two bays is that Garorim Bay has no large inputs of freshwater whereas Gyenonggi Bay is affected by freshwater discharged from the Han River. Each seawater sample (2 L) was filtered immediately through a Whatman GF/A filter (pore size: 1.6 μm, diameter: 45mm) to remove any suspended particles and eukaryotes [18 (link)–20 (link)] before being filtered through a 0.22 μm pore-size filter (diameter: 45mm, Supor polyethersulfone, Pall Life Sciences) to capture the archaeal and bacterial cells using a vacuum pump. The filters were preserved at -80°C until DNA extraction, which was performed after enzymatic lysis and phenol:chloroform purification [21 (link)]. The concentration of DNA was determined using a Nano-Drop ND-1000 spectrophotometer (NanoDrop Technologies, Wilmington, DE).

Sampling occurred at Marsh Landing, Sapelo Island, Georgia, U.S.A. (31°25'4.08 N, 81°17'43.26 W) as part of the Sapelo Island Microbial Observatory program (http://simo.marsci.uga.edu). Samples and environmental measurements were collected quarterly (2008: August 6–7, November 5–7; 2009: February 15–17, May 13–15, August 12–14) with each sampling expedition occurring at four consecutive high tides, resulting in two consecutive pairs of day-night samples per season. Cell collection for RNA extraction was conducted as described previously (Poretsky et al., 2009 (link); Gifford et al., 2011 (link)). Briefly, 6–8 L of water was pumped directly from a depth of 1 m and passed through a 3-μm pore-size prefilter (Capsule Pleated Versapor Membrane; Pall Life Sciences, Ann Arbor, MI, USA) and a 0.22-μm pore-size collection filter (Supor polyethersulfone; Pall Life Sciences). The 0.22-μm filter was placed in a WhirlPak bag and flash frozen in liquid nitrogen. Total time from start of filtration to flash freezing was 11–14 min.