Heterotrophic growth and oil production from Micractinium sp. ME05 using molasses
In this study the thermo-resistant green alga Micractinium sp. ME05 was cultivated in media containing molasses as a carbon source. Shake flask experiments and 2-L bioreactor experiments were conducted at different inoculum ratios, aeration rates, and agitation speeds. The experimental condition which resulted in the highest biomass concentration (3.73 ± 0.45 g L−1) with 10% inoculum in 500-mL flasks was scaled up to 2-L flasks at two aeration rates (0.25 and 0.5 L min−1). An increase in biomass concentration from 2.35 ± 0.53 to 3.06 ± 0.21 g L−1 was observed with an increase of aeration rate from 0.25 to 0.50 L min−1, which demonstrated significant effect of aeration rate on biomass concentration (p = 0.000 < 0.05). In 2-L bioreactor experiments, highest biomass productivity (0.53 ± 0.076 g L−1 day−1) and lipid productivity (7.7 ± 1.6 g L−1 day−1) were obtained with 5% (v/v) inoculum and 50 rpm agitation speed. The principal fatty acids were palmitic acid (C16:0) and linoleic acid (C18:2) comprising 30.2 ± 1.01 and 45.2 ± 1.32% of the total fatty acid content, respectively. Thus, the present study highlights the possibility of using molasses for biomass and lipid production with Micractinium sp. ME05 under different cultivation conditions. Using low cost feedstock such as molasses would be valuable in terms of evaluating waste materials for further biodiesel production.
KeywordsChlorophyta Micractinium sp. Molasses Heterotrophic growth Bioreactor
This study was carried out at the Middle East Technical University (METU) Biology Department Plant Biotechnology Laboratory and METU Food Engineering Department Bioprocess Laboratory. We would like to thank Asst. Prof. Dr. Melih Onay for his isolation and characterization of microalgal species used in this study.
This study was funded by the Scientific and Technological Research Council of Turkey (TUBITAK) Project Number 114Z487).
- Miller GL (1959) Use of dinitrosalicyclic acid reagent for determination of reducing sugar. Anal Chem 31:426–428Google Scholar
- Park KC, Whitney C, McNichol JC, Dickinson KE, MacQuarrie S, Skrupski BP, Zou J, Wilson KE, O'Leary JB, McGinn PJ (2012) Mixotrophic and photoautotrophic cultivation of 14 microalgae isolates from Saskatchewan, Canada: potential applications for wastewater remediation for biofuel production. J Appl Phycol 24:339–348CrossRefGoogle Scholar
- Anderson RA (2005) Photobioreactors and fermentors: the light and dark sides of growing algae. In: Andersen Robert (ed) Algal culturing techniques. Elsevier Academic Press, NY pp 189–203Google Scholar