Evaluation of Yarrowia lipolytica Oil for Biodiesel Production: Land Use Oil Yield, Carbon, and Energy Balance

Hindawi Journal of Lipids Volume 2018, Article ID 6393749, 6 pages https://doi.org/10.1155/2018/6393749 Research Article Evaluation of Yarrowia lipolytica Oil for Biodiesel Production: Land Use Oil Yield, Carbon, and Energy Balance Xochitl Niehus ,1,2 Leticia Casas-Godoy ,3 Francisco J. Rodr-guez-Valadez,1 and Georgina Sandoval 2 1 Centro de Investigación y Desarrollo Tecnológico en Electroquı́mica SC. Parque Tecnológico Querétaro Sanfandila, 76703 Pedro Escobedo, Querétaro, Mexico 2 Centro de Investigación y Asistencia en Tecnologı́a y Diseño del Estado de Jalisco (CIATEJ), 800 Normalistas Av., Guadalajara 44270, Mexico 3 Cátedras CONACYT- Centro de Investigación y Asistencia en Tecnologı́a y Diseño del Estado de Jalisco (CIATEJ), 800 Normalistas Av., Guadalajara 44270, Mexico Correspondence should be addressed to Georgina Sandoval; Received 30 May 2018; Revised 15 September 2018; Accepted 15 October 2018; Published 28 October 2018 Academic Editor: Gerhard M. Kostner Copyright © 2018 Xochitl Niehus et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Oils from yeasts have emerged as a suitable alternative raw material to produce biodiesel, due to their similar composition to common raw materials such as vegetable oils. Additionally, they have the advantage of not competing with human or animal feed, and, furthermore, they do not compete for arable land. In this work, a carbon and energy balance was evaluated for Yarrowia lipolytica as a model yeast, using crude glycerol from biodiesel as the only carbon source, which improves biodiesel overall yield by 6%. The process presented a positive energy balance. Feasibility of yeast oil as biodiesel substrate was also evaluated by determination of the lipid fatty acid profile and cetane number. Moreover, a comparison of oil yields, in terms of land use, between vegetable, microalgae, and yeast oils is also presented. The results showed that Y. lipolytica oil yield is considerably higher than vegetable oils (767 times) and microalgae (36 times). 1. Introduction Biodiesel has become the most sustainable and renewable alternative to fossil diesel. It is defined as a mixture of free fatty acid alkyl esters, usually obtained from vegetable oils and animal fats [1]. The use of these oils as raw materials accounts for around 88% of the production costs [2] and has also generated polemics about the usage of edible oils to produce biofuels while there is still hunger in the world. Therefore, many studies are focused on the utilization of lower-cost and nonedible feedstocks, such as waste or nonedible oils [1]. In this regard, microbial oils have emerged as alternative raw materials. Microbial oils are defined as the oils produced by oleaginous microorganisms, i.e., microorganisms able to accumulate more than 20% of their dry cell weight (DCW) as lipids in the form of droplets inside the cells [3]. This accumulation is mainly due to an excess of carbon (C) source and a limiting amount of another nutrient, such as nitrogen (N) [4, 5]. Lipids from yeasts are mainly triacylglycerols, which can be compared, in terms of their chemical composition, to lipids obtained from plant oilseeds (vegetable oils). Furthermore, yeasts can use a wide range of nutrient sources, including industrial wastes, which could reduce production costs. The main coproduct of biodiesel is crude glycerol, which before a highly cost purification process has a limited amount of applications. The increased availability of crude glycerol, resulting from the growing production of biodiesel, has attracted the attention of researchers. Several studies are focused on adding value to this coproduct by using it as a substrate for microbial cultures in biotechnological processes [6–10]. Among the most studied oleaginous yeasts, we can find Yarrowia lipolytica, a dimorphic yeast with a known genome [11]. In this work a recently isolated Y. lipolytica strain was cultured in crude glycerol as a model to evaluate its biomass energy potential and carbon balance. In addition, fatty acid 2 profile and cetane number were evaluated. Finally, a comparison of land use oil yields between vegetable, microalgae, and yeast oils is presented. To our knowledge, this is the first report of this kind that includes yeast oils. 2. Materials and Methods 2.1. Yeast Strain. The yeast strain used for the study was a Yarrowia lipolytica, which was previously isolated in our lab and selected by its lipid content and versatility to grow in different substrates. Yeast identification was performed by PCR-RFLP analysis according to Segura et al. [12]. This wild type yeast was deposited under the Budapest Treaty in the Agricultural Research Service Culture Collection (NRRL) with the number NRRL Y-50997. 2.2. Production of Yeast Oils. Yeast oils were produced in 500 mL Erlenmeyer flasks containing 100 mL of nitrogen limited medium. A nitrogen limited medium was prepared according to Suutari et al. [13], using crude glycerol instead of glucose. Cultures were inoculated with a 10 mL overnight preculture grown in YPD (20 g/L glucose, 20 g/L peptone, 10 g/L yeast extract). Liquid cultures were performed in duplicate on orbital shakers at 250 rpm and 30∘ C, for 72 h. Samples were taken during the production and frozen until further analysis. Crude glycerol was obtained from a local biodiesel producer. Unless otherwise stated, commercial grade chemicals were purchased from Sigma-Aldrich (Mexico). 2.3. Analytical Methods. During yeast oil production cell growth, lipid content, nitrogen, and glycerol consumption were analyzed for all the samples taken. Cell growth or biomass was determined by measuring the DCW after drying to constant weight. The lipid content was measured by the extraction of lipids from the cells using the method proposed by Schneiter et al. [14]. Lipid percentage was calculated using DCW and lipid content. Nitrogen consumption was reported as the sum of inorganic and organic nitrogen present in the supernatant, which were measured by the colorimetric techniques proposed by Chaney et al. [15] and Sun et al. [16], respectively. Biomass elemental composition was measured in washed and dried samples obtained from the final yeast culture and was determined using an EA 1108 Fisons instrument model EA1108 CHNS. Fatty acid profile of the final culture was analyzed in a gas chromatograph equipped with flame ionization detector (Perkin Elmer model AutoSystem XL, USA) using an Alltech AT-WAX 30mm × 0.25mm × 0.25 𝜇m capillary column (J and W Scientific, USA) and nitrogen as the carrier gas. Fatty acid methyl esters were identified by comparison of their retention times with commercial standards, and the lipid profile was obtained using methyl heptadecanoate as internal standard. All the measurements were performed in dupli (...truncated)