SUMMER-1 Cruise, RV García del Cid

Abstract

Probing the Rare Biosphere of the North-West Mediterranean Sea: An Experiment with High Sequencing Effort.Samples were taken at Station D, an open sea station at 40°52’N and 02°47’E in the NW Mediterranean Sea, during the SUMMER cruise between 13th and 22nd of September 2011 on board the RV “García del Cid”. The surface sample was taken at 5 m on the 15th of September and the bottom sample was collected at 2000 m depth on the 17th of September. Sampling was carried out with Niskin bottles mounted on a rosette with a conductivity-temperature-depth (CTD) profiler. Water was prefiltered through a 200 μm mesh and processed on board. To collect microbial biomass, 5–15 L of sea-water were prefiltered through a 3 μm pore size Durapore filter (Millipore, Cork, Ireland) and free-living bacterial biomass was collected on a 0.22 μm pore size Sterivex filter (Durapore, Millipore). The samples were filtered in succession using a peristaltic pump. The 0.22 μm pore size Sterivex unit was filled with 1.8 ml of lysis buffer (40 mM EDTA, 50 mM Tris-HCl, 0.75 M sucrose) and stored at –80°C. DNA was extracted by a standard protocol using phenol/chloroform . The same amount of DNA for both samples was sequenced