Evaluation of molasses and vinasse performance for lipid production from green microalgae

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2017
Engin, Işkın
Microalgae are considered a valuable source of energy that could be an alternative to fossil fuels. Due to their high photosynthetic efficiency and high biomass production, microalgae have drawn attention for biodiesel production. However, cost of carbon source is a major challenge in biodiesel production from microalgae. For this reason, alternative carbon sources are being considered. In this study, heterotrophic growth conditions for improvement of biomass production from thermo-resistant Micractinium sp. METUNERGY1405 (ME05) cells were optimized. Plackett-Burman (PB) design was used to screen glucose and yeast extract concentrations, pH, temperature, and inoculum ratio. Variables that were selected by the PB design (pH, temperature and glucose concentration) were further optimized using Box-Behnken design to increase biomass concentration. Molasses was used as an alternative carbon source for a cost-efficient biomass production. According to the results of statistical analysis, 0.41±0.02 g.L-1.day-1 of maximal biomass productivity was achieved by using 19g/L molasses, which revealed an increase in biomass productivity under optimized conditions and this biomass productivity was further improved to 0.53±0.038 g.L-1.day-1 by scaling up to 2L bioreactors. Also, Micractinium sp. ME05 was scaled up successfully in vinasse based media and a two-fold increase in biomass productivity was achieved in 5 L bioreactors (0.32±0.2 g.L-1.day-1) with respect to 500 mL flasks (0.16±0.01 g.L-1.day-1). High lipid content and rich FAME profile of Micractinium sp.ME05 grown in molasses and vinasse based media, could make these by-products desirable carbon sources for biodiesel production from Micractinium sp.ME05. Finally, with industrial by-products, molasses and vinasse, Micractinium sp. ME05 demonstrated remarkable biomass productivities, that were higher than those obtained with Micractinium sp. in previous studies. This is the first study that highlights the usage of industrial by-products as nutrients for a cost-efficient biomass and lipid production from native Micractinium sp. ME05 cells.

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Citation Formats
I. Engin, “Evaluation of molasses and vinasse performance for lipid production from green microalgae,” Ph.D. - Doctoral Program, Middle East Technical University, 2017.