FAMEs Profile of Oil Produced by Oleaginous Fungi Isolated from Fermented Beverage Wastewaters and Soil

Abstract

Fungal strains isolated from fermented maize (ogi) (PW) and sorghum-based brewery wastewaters (BW) and two soil isolates were evaluated for oleaginicity. The fungal isolates from the wastewater that had lipid content of at least 20% of their biomass were identified by both culture methods and internal transcribed spacer (ITS) 1-5.8S-ITS2 ribosomal DNA sequencing. The isolates were identified to be Aspergillus fumigatus (PW8), Aspergillus flavus (PW10), Candida tropicalis (PW16) and Aspergillus tubingensis (PW3), Trichosporon luoberi (BW7), Aspergillus sp. (BW4) and Candida tropicalis (BW1; BW3). FAMEs composition was determined for the four strains with the highest lipid content by acid-catalyzed transesterification and analyzed by Gas Chromatography-Flame Ionization Detector (GC-FID). Palmitoleic acid was the dominant fatty acid in M. circinelloides and T. reesei, and the best producers of capric and lauric acids were Aspergillus fumigatus and Aspergillus sp. (BW4), respectively. These fatty acids are beneficial in making cosmetics and pharmaceuticals (antimicrobials and dietary supplements). The analysis of the FAMEs profile in the species indicated low amounts or absence of some key long chain fatty acid (LCFA) constituents of biodiesels. Based on the FAMEs profile of M. circinelloides investigated, this strain could hold promise for use as feedstock for biodiesel with genetic engineering and a tailored lipid production favouring enrichment of LCFA.

Keywords: Fungal lipids, wastewater, fatty acid methyl ester, GC-FID