Analysis of photosynthetic pigments pathway produced by CO2-toxicity-induced Scenedesmus obliquus

Effective CO2 capture by the fed-batch culture of Chlorella vulgaris

“…The overall growth profile of C. vulgaris under various conditions suggests that algal growth was C-limited at low dCO2 concentrations and inhibited at high dCO2 concentrations. This finding is in line with previous studies investigating the impact of CO2 concentrations on the development of microalgae [10,13,42]. In this study, one may classify the C. vulgaris cultures into four groups according to their growth profiles with respect to the CO2 supplement regimes: strongly Climited group (FB_blank culture), slightly C-limited group (batch and FB_control cultures), C-saturated group (FB_1.55 and FB_1.62 g L -1 cultures) and C-toxic group (FB_1.75 and 1.88 g L -1 cultures).…”

“…A moderate increase in the availability of CO2 promotes algal growth [10,17]. In this study, the better media for C. vulgaris growth contained 1.55 and 1.62 g L -1 dCO2 where the cultures achieved the highest growth rates, final biomass productions and productivities, as well as the shortest doubling time (Table 2).…”

“…Despite the greater availability of CO2 in these two cultures, C limitation was still observed, as indicated by the increasing specific growth rate when C. vulgaris was grown in 1.55 and 1.62 g L -1 of dCO2 (µmax of 0.091 and 0.094 h -1 , respectively). Limited growth under atmospheric conditions has also been reported in the other Chlorella strains [17,44,45], and other microalgae such as N. oculata [13] and Scenedesmus obliqus [10].…”

“…Whitney et al [46] has illustrated that high CO2 concentration decreased the transmission of photoelectron signals, affecting algal photosynthetic activity and thereby lowering the biomass productivity. High CO2 concentration has also been found to induce reactive oxygen species and oxidative stress, inhibiting the growth of Arthrospira platensis [47] and S. obliqus [10]. Despite the CO2 inhibition at higher levels, the FB_1.75 g L -1 culture still had superior growth parameters than those for the FB_control culture.…”

“…In nature, the inorganic carbon (C) source for planktonic photosynthesis comes from the air which contains only 0.04% CO2 [7]. The low dissolved CO2 (dCO2) concentration in water at equilibrium (the diffusion coefficient is 10 4 times smaller than in air) generally cannot meet the optimal growth rate and high biomass yield [8][9][10][11]. To avoid C limitation, microalgae cultures can be injected with CO2-enriched air/flue gases [12,13].…”