0.2 μm pore size polycarbonate membrane filters

Water samples were collected from a marine aquaculture site around Xiamen coast, China, on 24 January 2016 and immediately filtered through 0.2-μm pore-size polycarbonate membrane filters (Millipore, Bedford, MA, United States). A 100 mL of filtrate was added to 150 mL of exponentially growing bacterial culture and incubated overnight at 28°C and 160 rpm in a shaker. Cultures were then centrifuged at 10,000 ×g for 20 min to remove bacteria. A 100 μL subsample of cell-free supernatant was added to 1 mL of exponentially growing culture, and then plaque assayed as described by Suttle and Chen (1992) (link). Each phage isolate was plaque purified at least three times.

To explore the composition and function of the entire prokaryotic community associated with the suspended and sinking particles, including the FL community, 2 L of water from both fractions was filtered using 0.2-μm-pore-size polycarbonate membrane filters (47-mm diameter); Millipore (Burlington, MA, USA) (115 (link)). The filters were stored at −80°C until further processing. DNA was extracted using the PowerSoil kit (Qiagen, Hilden, Germany) as described by M. Hirai et al. (116 (link)). The resultant DNA was sequenced by Admera Health Biopharma Services (South Plainfield, NJ, USA) (Text S1).