Utilização da citometria de fluxo multiparamétrica na monitorização da resposta...

• Author(s): Neves, Elisabete Dias das
• Date: 2011
• Persistent ID: http://hdl.handle.net/10400.5/4110
• Origin: Repositório da UTL
• Subject(s): Saccharomyces carlsbergensis; bioethanol; inhibition; formic acid; multiparameter flow cytometry
• Document Type: Master Thesis
• Language: Portuguese
• Advisor(s): Silva, Maria Teresa Saraiva Lopes da; Brito, Maria Luísa Castro e; Passarinho, Paula Cristina Varela

Description

Mestrado em Engenharia de Sistemas Bioenergéticos - Instituto Superior de Agronomia / Instituto Superior Técnico / Faculdade de Ciências. Universidade de Lisboa The concern with the environmental impacts regarding the use of fossil fuels in the energy sector has triggered the search for new renewable energy sources. The aim of this study was to monitor the physiological response of the yeast Saccharomyces carlsbergensis cells in fermentation assays performed with the addition of formic acid by multi-parameter flow cytometry. The biomass production was more affected by formic acid concentrations higher than 5 g.L-1. Nevertheless, the lowest biomass yield (0,034g.g-1) as well as the lower ethanol yield (35% reduction regarding the assay without inhibitor) were attained with 20g.L-1 of formic acid. The multi-parameter flow cytometry analysis showed that in the presence of 5 g.L-1 of inhibitor during the exponential growth phase there are some stress indicators such as the increase in the number of cells with depolarized membrane and the increase in the number of cells with reactive oxygen species, although the yeast continues to respond in terms of biomass and ethanol productions. The results on ethanol production indicate that the use of this yeast in lignocellulosic hydrolisates fermentation may be interesting due to its resistance to the effect of formic acid when compared to other yeasts like Saccharomyces cerevisae whose inhibition effects of formic acid are registered for concentrations over 4,6 g.L-1 (Larson et al., 2009).