Culturing of Synechococcus clones:
Monocultures of six clones of Synechococcus were used to examine variation and controls on Si quotas and rates of Si accumulation. Cultures were procured from the National Center for Marine Algae and Microbiota (NCMA) at the Bigelow Laboratory for Ocean Sciences in Boothbay Harbor, Maine. Many of these clones are also available in other culture collections and have various strain names; here we will refer to each by their NCMA strain number (a.k.a. CCMP number).
All clones were maintained in aged surface Sargasso Sea water with f/2 media constituents with 10 – 100 uM Si depending on the experiment as detailed below. The temperature was 21C with low light 65 microeinsteins per second per square meter (uE/m2/s) on a 12 h light:12 h dark photocycle. pH was regulated in all cultures by bubbling with humidified ambient air which was sterilized by passage through a bacterial filter prior to entering each culture vessel. Unless otherwise specified, all experiments were conducted under these temperature and light conditions. The pH was monitored daily and remained below 8.5 in all experiments.
Silicic acid conditions:
Six Synechococcus clones were grown in Sargasso Sea water under three silicic acid concentration conditions: 1 uM (ambient), 60 uM, and 120 uM. Macronutrients, trace metals, vitamins were used at f/2 media levels. Cellular quotas of biogenic silica were determined using NaOH–HF digestion in Teflon tubes as described in Krause et al. (2013)
Full methods are described in Brzezinski et al. (in review). (as of 05 Jan 2017)