University of Khartoum

Screening and Molecular Characterization of Oleaginous Yeasts and Their Potentiality for Single Cell Oil Production

Screening and Molecular Characterization of Oleaginous Yeasts and Their Potentiality for Single Cell Oil Production

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Title: Screening and Molecular Characterization of Oleaginous Yeasts and Their Potentiality for Single Cell Oil Production
Author: Elmahe, Rania Mohammed Abdel Rahman
Abstract: The study aimed to isolate the oleaginous yeast from local sources (rotten fruits, fruit juices, milk, fish and air) to identify and to study the possibility of production of single cell oil (SCO) when grown on specific media using wheat straw and sugarcane molasses as a cheap source of nitrogen and sugars. Isolated samples were collected from food processing factories, households and markets. Wheat straw was collected from cultivated wheat fields after harvesting and sugarcane molasses was obtained from the sugar factory. Thirty samples of yeast were isolated according to the different methods of isolation based on the source of isolation. The isolated yeast samples were characterized by microscopic appearance, colony morphology, physiological tests, assimilation tests and molecular identification. The effectiveness of oleaginous yeast to produce the single cell oil was studied, when the yeast was grown on wheat straw, detoxified liquid hydrolysate (DLH) and nondetoxified liquid hydrolysate (NDLH) and molasses. Single cell oil was extracted by hexane. Sacchromyces cerevisiae (isolated from rotten apple) with high oil productivity was used to study the characteristics of the produced oil which was grown on wheat straw and sugarcane molasses as substrate. The quality of single cell oil was compared to characteristics of common edible oil (Codex, 2003). Data were subjected to statistical analysis system using complete randomized design (ANOVA). Eighteen isolates were found to be yeast, and the profile of ten yeast samples were identified as Saccharomyces cerevisiae, while, one sample as Pichia guilliermondii. xi DLH wheat straw gave higher productivity of oil than NDLH wheat straw where, the highest oil productivity was 48 % achieved by yeast isolated from rotten apple on DLH wheat straw, while the lowest oil productivity was 9 % achieved by yeast isolated from rotten grape fruit on NDLH wheat straw. The highest oil productivity when using sugar cane molasses as substrate was 84 % achieved by yeast isolated from rotten apple, while the lowest level was 41 % achieved by yeast sample isolated from banana juice. Generally, Sacchromyces cerevisiae gave higher oil productivity (84 %), than Pichia guilliermondii (52%). The results indicated that most of the physicochemical properties of extracted oil were found to be within the recommended limit of the common edible oil reported by codex (2003) except the iron content; it ranged from 21 to 24 mg/kg, which was 4-5 times exceeded the permissible level of codex (2003). The saturated fatty acids of the produced DLH and NDLH and molasses oil were less than unsaturated fatty acids. In addition, single cell oil produced by molasses contains omega-6 fatty acid such as eicosapentaenoic and docosahexaenoic which are not found in vegetable oil. Oleaginous yeasts produce more oil from sugarcane molasses than wheat straw. Also the unsaturated fatty acids of wheat straw oil samples were higher than in molasses oil samples. The fatty acid profile of molasses oil was different from fatty acids profile of vegetable oils. The good physicochemical characteristics and fatty acids profile of single cell oil from wheat straw make it safe and a promising potential raw material for production of edible oil.
Description: 154 Pages
URI: http://khartoumspace.uofk.edu/123456789/27399
Date: 2018


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