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World J Microbiol Biotechnol. 2017 Nov 27;33(12):218. doi: 10.1007/s11274-017-2380-9.

Further investigation of relationships between membrane fluidity and ethanol tolerance in Saccharomyces cerevisiae.

Author information

1
Laboratory of Biomolecular Health and Food Sciences, Department of Chemistry, Universitas Padjadjaran, Jl. Raya Bandung-Sumedang km. 21, Jatinangor, 45363, West Java, Indonesia. ishmayana@unpad.ac.id.
2
School of Agricultural, Computational and Environmental Sciences, Faculty of Health, Engineering and Sciences, University of Southern Queensland, Toowoomba, QLD, 4350, Australia. ishmayana@unpad.ac.id.
3
School of Agricultural, Computational and Environmental Sciences, Faculty of Health, Engineering and Sciences, University of Southern Queensland, Toowoomba, QLD, 4350, Australia.

Abstract

Membrane lipid unsaturation index and membrane fluidity have been related to yeast ethanol stress tolerance in published studies, however findings have been inconsistent. In this study, viability reduction on exposure to 18% (v/v) ethanol was compared to membrane fluidity determined by laurdan generalized polarization. Furthermore, in the determination of viability reduction, we examined the effectiveness of two methods, namely total plate count and methylene violet staining. We found a strong negative correlation between ethanol tolerance and membrane fluidity, indicated by negative Pearson correlation coefficients of - 0.79, - 0.65 and - 0.69 for Saccharomyces cerevisiae strains A12, PDM and K7, respectively. We found that lower membrane fluidity leads to higher ethanol tolerance, as indicated by decreased viability reduction and higher laurdan generalized polarization in respiratory phase compared to respiro-fermentative phase cells. Total plate count better differentiated ethanol tolerance of yeast cells in different growth phases, while methylene violet staining was better to differentiate ethanol tolerance of the different yeast strains at a particular culture phase. Hence, both viability assessment methods have their own advantages and limitations, which should be considered when comparing stress tolerance in different situations.

KEYWORDS:

Ethanol tolerance; Generalized polarization; Membrane fluidity; Spectrofluorometry; Viability reduction; Yeast

PMID:
29181637
DOI:
10.1007/s11274-017-2380-9
[Indexed for MEDLINE]

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