AUTHOR=Serrazanetti Diana I. , Patrignani Francesca , Russo Alessandra , Vannini Lucia , Siroli Lorenzo , Gardini Fausto , Lanciotti Rosalba 

TITLE=Cell membrane fatty acid changes and desaturase expression of Saccharomyces bayanus exposed to high pressure homogenization in relation to the supplementation of exogenous unsaturated fatty acids

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.01105

DOI=10.3389/fmicb.2015.01105

ISSN=1664-302X

ABSTRACT=<p><bold>Aims:</bold> The aim of this work was to study the responses of <italic>Saccharomyces bayanus</italic> cells exposed to sub-lethal high-pressure homogenization (HPH) and determine whether the plasmatic membrane can sense HPH in the presence, or absence, of exogenous unsaturated fatty acids (UFAs) in the growth medium.</p><p><bold>Methods and Results:</bold> High-pressure homogenization damaged and caused the collapse of cell walls and membranes of a portion of cells; however, HPH did not significantly affect <italic>S. bayanus</italic> cell viability (less than 0.3 Log CFU ml<sup>-1</sup>). HPH strongly affected the membrane fatty acid (FA) composition by increasing the percentage of total UFA when compared with saturated fatty acids. The gene expression showed that the transcription of <italic>OLE1</italic>, <italic>ERG3</italic>, and <italic>ERG11</italic> increased after HPH. The presence of exogenous UFA abolished HPH-induced effects on the <italic>OLE1</italic> and <italic>ERG3</italic> genes, increased the percentage of membrane lipids and decreased the expression of <italic>OLE1</italic> and <italic>ERG3</italic> within 30 min of treatment.</p><p><bold>Conclusion:</bold> The results suggest a key role for UFA in the microbial cell response to sub-lethal stress. In addition, these data provide insight into the molecular basis of the response of <italic>S. bayanus</italic> to this innovative technology.</p><p><bold>Significance and Impact of the Study:</bold> Elucidation of the mechanism of action for sub-lethal HPH will enable the utilization of this technology to modulate the starter performance at the industrial scale.</p>