Centricon plus 70 ultracel pl 100

The seawater sample was collected from the pier of the Inter‐University Institute for Marine Sciences (IUI) in Eilat, Israel, on May 2015. The pier is 50 m long and the water depth is 5 m. The samples were concentrated 20 times using a Centricon Plus‐70 Ultracel PL‐100 (Merck Millipore, Tullagreen Carrigtwohill, Ireland) and then sent to the laboratory in Oxford on ice.

Two 10 L seawater samples were collected by Schindler samplers from the euphotic zone of the Yellow Sea, China (the geographical position is shown in Supporting Information Fig. S2). The seawater was transported using portable cooler with ice to laboratory for analysis. All samples were prefiltered through 8 μm pore size filter membranes using a peristaltic pump when being decanted from the sampler.
The original seawater sample was served as a primary control (without incubation). One liter of seawater was taken and spiked with ¹²C or ¹³C NaHCO₃ with a final concentration of 2 mM, and the control was not treated with any chemicals. The samples were incubated in closed bottles at room temperature for 5 days with natural light. The four sets of samples, including primary control, incubation control, ¹²C or ¹³C NaHCO₃ spiking treatments, were all in triplicate. After pretreatments, cells in those samples mentioned above were harvested by 0.22 μm pore size membrane filtration using a peristaltic pump and then the cells were sealed and stored at −80°C freezer until DNA extraction.
After incubation, cells in samples spiked with ¹²C and ¹³C NaHCO₃ were enriched by passing 70 ml seawater through the Centricon® Plus‐70 Ultracel PL‐100 (Merck Millipore, Billerica, USA) respectively. Then, the cells were used for Raman activated cell sorting based on functions of ¹³C NaHCO₃ utilization.