Temperature incubations of microbial communities from two different locations in Fram Strait - flow cytometry raw data

This dataset encompasses data derived from two temperature incubation experiments aboard the RV Polarstern, using a unicellular microbial community collected from different stations in the Fram Strait during the PS126 campaign on June 1st and 13th, 2021 (Soltwedel, 2021). The initial samples were obtained from a depth of 15 m using CTD-bound Niskin bottles (SBE 32 Carousel Water Sampler attached to a Seabird SBE911+ CTD system; Seabird Scientific, Bellevue, WA, USA) and, following filtration through a 150 µm mesh, the communities were incubated on plankton wheels within three temperature-controlled containers. To simulate current and potential future temperature scenarios in the Arctic Ocean, we selected a control temperature of 2 °C, an intermediate warming scenario of 6 °C, and a higher warming scenario of 9 °C while varying several other parameters such as light, nutrients and dilution level. Parameters were sampled at several timepoints throughout the two incubations. For flow cytometry, 3.5 ml of samples were fixed with hexamine-buffered formalin (0.5% final concentration), incubated in the dark for 15 minutes and stored at −80 °C. Samples were thawed and vortexed before 2 µl of Fluoresbrite® Multifluorescent Microspheres beads (1 µm, Polysciences, Warrington, PA, USA) were added to 1 ml of sample. Each sample was measured for three minutes at high flow speed on an Accuri C6 flow cytometer (BD Sciences, Franklin Lakes, NJ, USA), using a threshold of 900 on the FL-3 channel. Subsequently, the samples were incubated for 20 minutes with SYBR® green dye (1x in TE buffer; Thermo Fisher Scientific, Waltham, MA, USA) and then measured again for two minutes at a slow flow speed with a threshold of 900 on the Fl-1 channel on the same device. The dataset provides valuable insights into the temperature responses of Arctic microbial communities.