Biomass production and carbon dioxide fixation by Aphanothece microscopica Nägeli in a bubble column photobioreactor

The objective of the present study was to evaluate the growth kinetics of Aphanothece microscopica Nägeli under different conditions of temperature, light intensity and CO2 concentration. The growth kinetics of the microorganism and carbon biofixation were evaluated using a central composite design, considering five different temperature levels (21.5, 25, 30, 35 and 38.5 °C), light intensities (0.96, 3, 6, 9 and 11 klux) and carbon dioxide concentrations (3, 15, 25, 50 and 62%). The results obtained showed the effects of temperature, light intensity and CO2 concentration (p < 0.05) on the photosynthetic metabolism of the microorganism. Response surface methodology was adequate for process optimisation, providing a carbon fixation rate to the order of 109.2 mg L−1 h−1 under conditions of 11 klux, 35 °C and 15% carbon dioxide, representing an increase of 58.1% as compared to the conditions tested initially.