2- Phenylethanol stress responses in Kluyveromyces marxianus CCT7735

• Ano de defesa: 2019
• Autor(a) principal: Balbino, Thércia Rocha
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Microbiologia Agrícola
• Palavras-chave em Português: Leveduras; Compostos aromáticos; Genética e Fisiologia de Micro-organismos
• Link de acesso: https://locus.ufv.br//handle/123456789/32207

2-phenylethanol (2-PE) is a higher aromatic alcohol that has been used as ingredient in both cosmetic and food industries due to its rose-like aroma and colorless aspect. The 2-PE production by chemical synthesis is undesirable due to the use of harmful precursors and formation of unwanted byproducts. Since the 2-PE extraction from plants and flowers is costly, its production by yeasts is of great interest. Yeasts can synthesize 2-PE from L- phenylalanine (L-Phe) through the Ehrlich pathway or by de novo synthesis from sugars through the Shikimate pathway. Recently, K. marxianus CCT 7735 was selected as the best producer of 2-PE among yeasts isolated from Brazilian environments. However, K. marxianus, like other yeasts, has its growth strongly inhibited by 2-PE concentrations superior to 2.0 g/L. Herein, we evaluated in K. marxianus CCT 7735 the damages caused by 2-PE exposure and its adaptative responses. Yeast batch cultures were carried out under nonstress and 2-PE stress conditions. The stress condition was established by adding 3.0 g/L of 2-PE to exponentially growing yeast batch cultures and samples were analyzed during 1, 2, 4, 8 and 12 h of cultivation. Under 2-PE stress, the K. marxianus growth, glucose uptake, fermentative metabolism, membrane permeability and cell viability were impaired. In addition, both morphology and roughness of K. marxianus were altered in response to stress condition. Remarkably, the reactive oxygen species (ROS) increased immediately upon 2-PE exposure. K. marxianus CCT 7735 restarted growth after 4 h of stress, suggesting an adaptation to the 2-PE. The adaptive responses included the increase in ergosterol content, changes in membrane fatty acid composition, exopolymer production and elimination of reactive oxygen species. Therefore, our results provided insights to better understand the 2-PE effects on K. marxianus and its adaptative responses. Keywords: Yeast. Aromatic alcohol. Adaptive responses. Morphology. Membrane composition.