Publicação
Use of n-alkanes as substrate by Yarrowia lipolytica
| Resumo: | Hydrocarbons have become one of the most important types of organic pollutants due to splits during the processes of petroleum manipulation and inadequate release of hydrocarbons in several industrial effluents (plastic, cosmetic, solvents and pharmaceutical industries). One approach to treat these residues is their degradation by microorganisms. Yarrowia lipolytica is a non-conventional yeast, strictly aerobic and is often isolated from oilpolluted environments, dairy products, meat and poultry products. Y. lipolytica is able to use n-alkanes, fatty acids and oils as carbon sources, making this yeast a potential agent for remediation of oily wastes. In this work, the main goal was to evaluate the ability of Y. lipolytica W29 to use hexadecane as carbon source and study the effect of several cultivation parameters (nitrogen source, surfactants and oxygenation) that could affect the yeast performance. Initially, the effect of two hexadecane concentrations on yeast growth was tested and it was observed a significant growth with 5 g·L-1 of hexadecane, whereas with 10 g·L-1 of hexadecane no cellular growth was observed. However, the addition of silicone oil to the culture with 10 g·L-1 of hexadecane eliminated toxic effects and dispersion problems, leading to a considerable yeast growth. It was also observed that the addition of Tween 80 and a nitrogen source (YNB) favored yeast growth in media with hexadecane as carbon source. The increase of oxygenation conditions did not improved cellular growth and hexadecane consumption. In the experiments carried out with lower agitation and aeration rates, yeast cells accumulated 26 % of their cell dry weight as microbial lipids and shift their morphology from oval form to hyphae form. The results reported herein prove that Y. lipolytica W29 is able to grow in hexadecane medium, producing simultaneously biomass and microbial lipids. Thus, this approach may be adapted to real effluents from refinery industries or other effluents containing hexadecane. |
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| Autores principais: | Ferreira, Ângela Sofia Oliveira |
| Assunto: | Yarrowia lipolytica Alkanes Hexadecane Biodegradation Dissolved oxygen Alcanos Hexadecano Biodegradação Oxigénio dissolvido |
| Ano: | 2016 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Hydrocarbons have become one of the most important types of organic pollutants due to splits during the processes of petroleum manipulation and inadequate release of hydrocarbons in several industrial effluents (plastic, cosmetic, solvents and pharmaceutical industries). One approach to treat these residues is their degradation by microorganisms. Yarrowia lipolytica is a non-conventional yeast, strictly aerobic and is often isolated from oilpolluted environments, dairy products, meat and poultry products. Y. lipolytica is able to use n-alkanes, fatty acids and oils as carbon sources, making this yeast a potential agent for remediation of oily wastes. In this work, the main goal was to evaluate the ability of Y. lipolytica W29 to use hexadecane as carbon source and study the effect of several cultivation parameters (nitrogen source, surfactants and oxygenation) that could affect the yeast performance. Initially, the effect of two hexadecane concentrations on yeast growth was tested and it was observed a significant growth with 5 g·L-1 of hexadecane, whereas with 10 g·L-1 of hexadecane no cellular growth was observed. However, the addition of silicone oil to the culture with 10 g·L-1 of hexadecane eliminated toxic effects and dispersion problems, leading to a considerable yeast growth. It was also observed that the addition of Tween 80 and a nitrogen source (YNB) favored yeast growth in media with hexadecane as carbon source. The increase of oxygenation conditions did not improved cellular growth and hexadecane consumption. In the experiments carried out with lower agitation and aeration rates, yeast cells accumulated 26 % of their cell dry weight as microbial lipids and shift their morphology from oval form to hyphae form. The results reported herein prove that Y. lipolytica W29 is able to grow in hexadecane medium, producing simultaneously biomass and microbial lipids. Thus, this approach may be adapted to real effluents from refinery industries or other effluents containing hexadecane. |
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