Fig. 2. Stress quantification. The lipid content of the cells as a function of total N in
algae. Cellular N is used here as a proxy for N stress. The vertical, dotted lines signify
the levels of N stress at which lipid accumulation began and ceased in each species.
The level of N stress that triggered the onset of lipid accumulation was unique for each species and ranged from minimal to severe stress. In general, the species that accumulated the highest lipid content were the species that responded to the least stress. The range in cellular N over which lipid accumulation occurred is proportional to the amount of growth and lipid accumulation that occurred concurrently. Species that grew and accumulated lipids concurrently had higher lipid productivity.
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