Single cell oil of oleaginous marine microbes from Saudi Arabian mangroves as a potential feedstock for biodiesel production

Abstract

This study aims to explore microbes from mangroves in Saudi Arabia for their abilities to produce high level of lipids. Mangroves are seldom investigated for oleaginous microbes. A total of 961 isolates of yeasts and filamentous fungi were isolated from 144 submerged marine samples include: 68 decaying leaves of Avicennia marina, 33 decaying thalli of Zostera marina, 14 decaying pneumatophores of Avicennia marina, 9 crab shells, 8 sediment, 7 decaying thalli of Turbinaria ornata and 5 decaying thalli of Cystoseira myrica. Samples were collected from four mangrove sites: Al-Leith, Jeddah and Yanbu at the Red Sea coast and the Syhat mangroves at the Arabian Gulf coast. Isolated fungi were grouped into 62 morphological types that include: 21 yeasts and 41 filamentous fungi. Fifty-four isolates of thraustochytrids were cultured from the four mangrove sites and were grouped into 22 strains. Two oleaginous yeasts: Hortaea werneckii and Rhodotorula mucilaginosa and four Aurantiochytrium strains produced high dry weight ranged between 32 and 49.3 g/L of which 35.2–62 % lipid and their fatty acid profile were determined using GC/MS. Palmitic acid was the major fatty acid in the lipid of the four thraustochytrid isolates and ranged between 5.71 and 82 % of the total fatty acids, 9-Octadecenamide, (Z)- was the major fatty acid amide in the lipid of the two yeast isolates and two thraustochytrid isolates and ranged between 26.94 and 56.63 %, followed by 13-Docosenamide, (Z)- (20.44–34.99 %) from the same four isolates. Other major lipid compounds were: Hexadecanamide (4.35–7.19 %), Cholestrol (7.24–15.07 %), Butylated Hydroxytoluene (3.46–15.76 %), Octadecanamide (3.95–7.9 %), Phenol, 2-(1,1-dimethylethyl)-5-methyl- (1.78–10.33 %) and Pentadecanoic acid (7.47 %).