Production of sophorolipds with a branched hydrophobic tail

• Autor(a) principal: Teixeira, Liliana Patrícia dos Reis
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/15310
• topic: Biotecnologia; Leveduras; Biosurfactantes; Starmerella bombicola

Sophorolipids are a type of biosurfactants produced by several microorganisms, including the yeast Starmerella bombicola. They find application mainly due to their emulsifying activity and antimicrobial properties. Sophorolipids produced by Starmerella bombicola are composed by one sophorose molecule and a hydroxylated fatty acid of 16 or 18 carbon atoms. One or two acetylations can occur, one on each glucose, and a lactonization as well. Despite the interesting characteristics of classic sophorolipids produced by the referred yeast, there are indications that sophorolipids with branched a hydrophobic tail have higher activity at lower temperatures. These sophorolipids are produced by Rhodotorula bogoriensis, however the yields obtained with this yeast are low. By producing these sophorolipids in Starmerella bombicola, the yields obtained could be higher. Furthermore, the production of these novel sophorolipids will allow broadening of the biosurfactants applications. This thesis describes two approaches to produce sophorolipids with a branched hydrophobic tail: use of Guerbet alcohols as substrates for the Starmerella bombicola culture, and the introduction of genes that will take care of the in-chain hydroxylation of the sophorolipids. Guerbet alcohols are branched molecules, and are expected to be incorporated in the sophorolipids molecules. The genes to be used are from Elizabethkingia meningoseptica and Rhodococcus rhodochrous and encode for an oleate hydratase, an enzyme responsible for the conversion of oleic acid into 10-hydroxystearic acid.