Oleaginous yeasts from Ethiopia

Abstract

Oleaginous microorganisms can produce high amounts of oil (>20 % of their biomass) under suitable cultivation conditions. In this research work 200 samples were collected from soil, plant surfaces (leaves, flowers and fruits), waste oils from traditional oil milling houses and dairy products (cheese, milk and yoghurt) in Ethiopia. Three hundred and forty yeast colonies were isolated from these samples. By applying Sudan III staining tests, 18 strains were selected as possible oleaginous yeasts. The 18 strains were identified and characterized for their lipid production as a feedstock for biodiesel production in the future. They were identified using morphological and physiological methods as well as sequencing the 3′end of the small-subunit rRNA gene, the internal transcribed spacer regions (ITS; ITS 1, ITS 2 and the intervening 5.8S rRNA gene), and the D1/D2 domain of the 26S rRNA gene. The 18 yeasts were identified as Cutaneotrichosporon curvatus (syn, Cryptococcus curvatus) (PY39), Rhodotorula kratochvilovae (syn, Rhodosporidium kratochvilovae) (SY89), Rhodotorula dairenensis (SY94) and Rhodotourula mucilaginosa (SY09, SY18, SY20, PY21, PY23, PY25, SY30, PY32, SY43, PY44, SY52, PY55, PY61, SY75 and PY86). Under nitrogen-limited cultivation conditions, R. mucilaginosa PY44 produced the highest biomass (15.10 ± 0.54 g/L), while R. mucilaginosa PY32 produced the lowest biomass (10.32 ± 0.18 g/L). The highest lipid yield of 6.87 ± 0.62 g/L and lipid content of 46.51 ± 0.70 % were attained by C. curvatus (syn, C. curvatus) PY39. On the other hand, R. mucilaginosa PY61 gave the lowest lipid yield (2.06 ± 0.52 g/L) and R. mucilaginosa SY52 gave the lowest lipid content of 16.99 ± 0.85 %. The results in this research work suggest that much more oleaginous yeasts can be isolated from Ethiopian environment. On the basis of their substantial lipid production abilities, the three oleaginous yeast strains PY39, SY89 and SY18 were selected and recommended for further optimization processes.

The Oleaginous Red YeastRhodotorula/Rhodosporidium: A Factory for Industrial Bioproducts

“…The strain was originally discovered in a screen for oleaginous yeasts in Ethiopia. Of the 340 yeast isolates screened, 18 tested positive for oil production, and a R. kratochvilovae strain was one of three chosen as best candidates for further optimization based on productivity [88]. Multiple parameters of its cultivation were optimized for lipid production [89] prior to being used to create SCO.…”

Optimization of cultivation conditions for biotechnological production of lipid by Rhodotorula kratochvilovae (syn, Rhodosporidium kratochvilovae) SY89 for biodiesel preparation

“…For details Jiru et al (2016) can be referred. Therefore, the yeast strain SY89 was used in the subsequent analyses.…”

Development of Rhodotorula mucilaginosa strain via random mutagenesis for improved lipid production

“…Since random mutations using EMS was performed in this study, it is difficult to predict the types of mutation generated and details on the specific genes affected were not within the scope of this project. Oleaginous microorganisms have different capabilities in lipid accumulation due to their respective genetic makeup, biochemistry and structural composition (Wynn and Ratledge, 2006;Nigam and Singh, 2014;Jiru et al, 2016). Even the strains within the same species might have different abilities in accumulating lipid (Jiru et al, 2016).…”