Optimization of Chlorella vulgaris cultivation grown in waste molasses
syrup using mixture design
Abstract
The aim of this study was to determine and optimize culture media for
Chlorella vulgaris microalgae under mixotrophic conditions using waste
molasses as a cheap carbon source containing both organic carbons and
other nutrients. In the current study, at first the growth and lipid
productivity of Chlorella vulgaris were assessed in different culture
media and the best media was selected for mixotrophic growth conditions.
Significant medium ingredients were screened through Plackett–Burman
design. Then ingredients with positive effect were considered as a
mixture component and their combinations were evaluated on lipid
productivity using mixture design. According to results, Zarrouk medium
was considered as the base medium with the highest biomass and lipid
productivity of 72 and 7.1 mg/l.d , respectively. Based on the
Plackett–Burman design, out of eleven factors, molasses, NaNO3 and
K2HPO4 demonstrated key roles in biomass and lipid productivity in
mixotrophic conditions. Consequently, the selected three factors were
investigated by mixture design. The results showed that high
concentration of molasses causes decrease in biomass and lipid
productivity due to high turbidity and a blend consisting of
approximately 9.5 g/l molasses, 5 g/l NaNO3 and 0.15 g/l K2HPO4 was
found as the optimum mixture with obtained lipid productivity of 115
mg/l.d. In conclusion, waste molasses can be used as a promising
feedstock for cost effective cultivation of C. vulgaris.