Growth rates of UWO241 and C. reinhardtii at different steady-state temperatures
We compared the effects of temperature on growth in the psychrophile UWO241 and the mesophile C. reinhardtii . The growth rate of UWO241 cultured at 4°C (the approximate temperature in its natural environment) was 0.019 h-1; however, maximal growth rates were achieved at 10°-15°C (0.025-0.030 h-1; Figure 1A). We observed lower growth rates in UWO241 at 17°C (0.013 h-1), and no growth was observed at 20°C. In accordance with previous reports (Schroda, Hemme & Mühlhaus 2015),C. reinhardtii exhibited maximal growth rates when cultured at 28°C (0.048 h-1) and lower rates at growth temperatures both higher and lower than this range (Figure 1B). Despite a longer lag phase (not shown), C. reinhardtii cultures were able to grow at 10° and 15°C, albeit at a decreased rate (0.025 and 0.034 h-1, respectively) compared to growth at 28°C (Figure 1B). This low temperature growth rate for C. reinhardtii was comparable to the maximum growth rates of UWO241 between 10°-15°C (Figure 1A). We did not observe growth of the mesophilic alga at 5°C or 40°C.