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Analysis of growth and intracellular product synthesis dynamics of a microalga cultivated in wastewater cocktail as medium

De Bhowmick, Goldy, Sen, Ramkrishna, Sarmah, Ajit K.
Biochemical engineering journal 2019 v.149 pp. 107253
Chlorella minutissima, cell growth, equations, lipid content, lipids, lutein, microalgae, models, nitrates, prediction, specific growth rate, wastewater
Kinetic modelling of cell growth and production dynamics (lipid and lutein) of Chlorella minutissima cultivated in cocktail wastewater medium following Taguchi’s L9 (4-factors-3-levels) array is reported. Monod model and a logistic equation were used to define cell growth whereas for lipid and lutein the Luedeking–Piret's equation was considered. Also, Kono-Asai’s model was used to analyze lipid product formation rate with growth rate. Monod kinetics constants: maximum specific growth rate (μmax) were highest for S5 and S3 (1.955 ± 0.01; 1.258 ± 0.03 d−1) and substrate affinity coefficient (KS) for S1 and S7 (345.4 ± 1.45; 35.25 ± 5.2 mg L−1). Kinetic constant values exhibited that Chlorella was able to grow faster under S3, S4, S5 and S7 cultivation conditions with high affinity for growth limiting substrate (nitrate), as indicated by low Ks value. Luedeking-Piret’s model predictions indicated that lipid was growth associated, whereas lutein was non-growth associated. Kono-Asai’s model reconfirmed Luedeking-Piret’s predictions for lipid. The models used would allow to select the dilution range of wastewaters and understand the product synthesis dynamics of the alga. Overall, highest growth yield and product yield coefficients were recorded for S3 and spectroflurometric analysis specified S3 cultivation condition to enhance the neutral lipid content up to 5.13 ± 0.18 μg mL−1.