Production of sophorolipids from winterization oil cake by solid-state fermentation: Optimization, monitoring and effect of mixing

• Published in: Biochemical engineering journal 2016-11, Vol.115, p.93-100
• Main Authors: Jiménez-Peñalver, Pedro, Gea, Teresa, Sánchez, Antoni, Font, Xavier
• Format: Article
• Language: English
• Subjects: Biosurfactant; Oil cake; Solid-state fermentation; Sophorolipid; Starmerella bombicola
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2016.08.006

[Display omitted] •Sophorolipids (SLs) are produced by solid-state fermentation (SSF) of organic wastes.•Starmerella bombicola grows on a mixture of winterization oil cake, molasses and straw.•S. bombicola produced 0.179g of SL per g dry matter in 10days.•Mixing at 3, 5 and 7days increased SL production to 0.235g per g dry matter.•SL yield correlates linearly with cumulative oxygen consumption. Sophorolipids (SLs) are a group of extracellular biosurfactants produced by the yeast Starmerella bombicola. The present study explored the use of winterization oil cake (WOC), a residual oil cake that comes from the oil refining industry, as a substrate for the production of SLs by solid-state fermentation (SSF). Sugar beet molasses (MOL) was used as a co-substrate and S. bombicola ATCC 22214 as the inoculum. Fermentation was performed on the 100-g scale and was optimized in terms of the ratio of substrates and the aeration rate using response surface methodology. The optimized SSF process (1:4 MOL:WOC mass ratio and 0.30Lkg−1min−1 aeration rate), carried out under static conditions, was monitored for 10days with a maximum SL yield of 0.179g per g DM (dry matter). The effect of intermittent mixing on the process was also investigated. Mixing caused a 31% increase in SL production, with a total yield of 0.235g per g DM. The Oxygen Uptake Rate (OUR) and the Cumulative Oxygen Consumption (COC) were used to monitor the biological activity of the fermentation processes. There were significant correlations between the SL yield and the oxygen and fats consumed. The SLs were characterized by FTIR and 1H NMR analysis.