Figure 1
Characterization of growth, gametogenesis, and lipid content in B. sudeticus . (A) B. sudeticus culture reaches relatively high maximal cell density. Growth curves of B. sudeticus (in red) and C. reinhardtii (in black) in various media indicated are shown. X- and Y-axis indicate time (in day) and cell dry weight (CDW; in g/L), respectively. HS and BB stand for High Salt and Bold-modified Bristol media, respectively. Error bars represent the standard deviation of triplicate samples. (B) Gametogenesis is induced by ND in B. sudeticus. Upper panel shows a gamete whose tip of flagella is denoted by an arrow. Bottom panel shows part of conical flasks in which sedimented cell aggregates are denoted by an arrow-head. Medium with nitrogen (+N2) or without nitrogen (-N2) is indicated. (C) Lipid accumulation is enhanced by ND in B. sudeticus. Left panel shows the increased intensity of Nile red signal in cells after ND. X- and Y-axis indicate the time (in day) and Nile red signal level (in arbitrary units), respectively. Nile red signal level of cell samples are based on the median level derived from FACS analysis as shown in the mid panel. Right panel shows the Nile red stained cells prior to (+N2) and after (-N2) ND. (D) Level of triacylglycerol (TAG) and squalene is increased in B. sudeticus following ND. Left panel shows the TLC analysis and right panel shows the GC-MS analysis (MS result is not shown) of total lipid in B. sudeticus prior to (+N2) and after (-N2) ND. (E) Contents of nitrogen (N), carbon (C), and total lipid (TL). Bar-plots show the level of N, C, and TL against CDW in nitrogen-replete (+N2) and nitrogen-starved (-N2) cells.