Enhancing the value of nitrogen from rapeseed meal for microbial oil production
2012
Uçkun Kiran, Esra | Salakkam, Apilak | Trzcinski, Antoine P. | Bakir, Ufuk | Webb, Colin
Rapeseed meal, a major byproduct of biodiesel production, has been used as a low-cost raw material for the production of a generic microbial feedstock through a consolidated bioconversion process. Various strategies were tested for the production of a novel fermentation medium, rich in free amino nitrogen (FAN): commercial enzymes (CEs) (2.7mgg⁻¹ dry meal), liquid state fungal pre-treatment (LSF) using Aspergillus oryzae (4.6mgg⁻¹), liquid state fungal pre-treatment followed by fungal autolysis (LSFA) (9.13mgg⁻¹), liquid state pre-treatment using fungal enzymatic broth (EB) (2.1mgg⁻¹), but the best strategy was a solid state fungal pre-treatment followed by fungal autolysis (34.5mgg⁻¹). The bioavailability of the nitrogen sources in the novel medium was confirmed in fed-batch bioreactor studies, in which 82.3g dry cell L⁻¹ of the oleaginous yeast Rhodosporidium toruloides Y4 was obtained with a lipid content of 48%. The dry cell weight obtained was higher than that obtained using conventional yeast extract, due to a higher total nitrogen content in the novel biomedium. The fatty acids obtained from the microbial oil were similar to those derived from rapeseed oil.
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