Utilisation of potato processing wastewater for microbial lipids and γ-linolenic acid production by oleaginous fungi

BACKGROUND: Microbial lipids are considered as the starting material for production of second-generation biofuels and their polyunsaturated fatty acids are rich sources of neutraceuticals. Exploring cheap feedstock for producing microbial lipids is necessary. The present study examined the potential of microbial lipids and γ-linolenic acid (GLA) production by two oleaginous fungi, Aspergillus flavus I16-3 and Mucor rouxii, with potato processing wastewater as a low-cost or no-cost nutrient source. RESULTS: Biochemistry and physiology of two oleaginous fungi, A. flavus I16-3 and M. rouxii, on lipid accumulation showed the two fungi grew well and efficiently utilised the starch in wastewater. On average (P < 0.05), 2.8 and 3.6gL^-1 of lipids were produced by A. flavus I16-3 and M. rouxii, respectively, with maximum GLA yields of 60 and 100mgL^-1. Addition of nutrients to raw wastewater significantly improved (P < 0.05) the lipid and GLA yields; 3.5 and 4.2gL^-1 of lipids, and 100 and 140mgL^-1 of GLA were produced by A. flavus I16-3 and M. rouxii, respectively. In addition, the wastewater was efficiently treated, with soluble chemical oxygen demand, total soluble nitrogen and total soluble phosphorus removals up to 60% and 90%, 100% and 98%, and 92% and 81% by A. flavus I16-3 and M. rouxii, respectively. CONCLUSION: This study demonstrated an alternative approach to valorise potato processing wastewater to produce microbial lipids and GLA (nutraceuticals).