Thermal constraints on growth, stoichiometry and lipid content of different groups of microalgae with bioenergy potential

Temperature has a range of effects on population demographic rates and physiology of microalgae for potential bioenergy application. The changes in microalgal growth, stoichiometry and cellular lipid contents of 14 different microalgae species with high bioenergy potentials in response to different temperature between 10 and 35 A degrees C were investigated. For most of the chosen microalgae, the specific growth rate increased with temperature over most of the range. On the other hand, the biomass density of most of the selected species declined with temperature at stationary phase. Certain cyanobacteria failed to grow below 20 A degrees C, while eukaryotes had a wider temperature range. Lipid content, by contrast, showed different responses to temperature among the 14 species. Nine of the species showed a positive response with increased temperature, while others showed neural or unimodal response. Cellular C:N and C:P ratios were mostly unimodally related to temperature. Some eukaryotic species showed the lowest total lipid contents but the highest C:N and C:P ratios, the fastest growth, and the highest biomass density at their stationary phases. The results indicated that the responses of the life history and cellular stoichiometry to temperature were more consistent across microalgae than that of total lipid content.