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Encapsulation-induced stress helps Saccharomyces cerevisiae resist convertible Lignocellulose derived inhibitors.

Westman JO, Manikondu RB, Franzén CJ, Taherzadeh MJ - Int J Mol Sci (2012)

Bottom Line: It was shown that encapsulation increased the tolerance against readily convertible furan aldehyde inhibitors and to dilute acid spruce hydrolysate, but not to organic acid inhibitors that cannot be metabolized anaerobically.Gene expression analysis showed that the protective effect arising from the encapsulation is evident also on the transcriptome level, as the expression of the stress-related genes YAP1, ATR1 and FLR1 was induced upon encapsulation.The transcript levels were increased due to encapsulation already in the medium without added inhibitors, indicating that the cells sensed low stress level arising from the encapsulation itself.

View Article: PubMed Central - PubMed

Affiliation: School of Engineering, University of Borås, 501 90 Borås, Sweden; E-Mails: rameshmanikondu@hotmail.com (R.B.M.); mohammad.taherzadeh@hb.se (M.J.T.) ; Chemical and Biological Engineering-Industrial biotechnology, Chalmers University of Technology, 412 96 Göteborg, Sweden; E-Mail: franzen@chalmers.se.

ABSTRACT
The ability of macroencapsulated Saccharomyces cerevisiae CBS8066 to withstand readily and not readily in situ convertible lignocellulose-derived inhibitors was investigated in anaerobic batch cultivations. It was shown that encapsulation increased the tolerance against readily convertible furan aldehyde inhibitors and to dilute acid spruce hydrolysate, but not to organic acid inhibitors that cannot be metabolized anaerobically. Gene expression analysis showed that the protective effect arising from the encapsulation is evident also on the transcriptome level, as the expression of the stress-related genes YAP1, ATR1 and FLR1 was induced upon encapsulation. The transcript levels were increased due to encapsulation already in the medium without added inhibitors, indicating that the cells sensed low stress level arising from the encapsulation itself. We present a model, where the stress response is induced by nutrient limitation, that this helps the cells to cope with the increased stress added by a toxic medium, and that superficial cells in the capsules degrade convertible inhibitors, alleviating the inhibition for the cells deeper in the capsule.

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Gene expression in different media after two hours of anaerobic batch cultivations; (A, C and E) YAP1, ATR1 and FLR1 respectively, relative to the level of TAF10, (B, D and F) YAP1, ATR1 and FLR1 respectively, relative to the expression level in DGM, for free yeast (white) and encapsulated yeast (black). The error bars depict variation in two biological replicates. The equality of means was tested using the logarithm of the relative gene expression in two-sided t-tests, assuming equal variance. Observed p-values are shown under each pair (Data from free yeast is from [14]).
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f2-ijms-13-11881: Gene expression in different media after two hours of anaerobic batch cultivations; (A, C and E) YAP1, ATR1 and FLR1 respectively, relative to the level of TAF10, (B, D and F) YAP1, ATR1 and FLR1 respectively, relative to the expression level in DGM, for free yeast (white) and encapsulated yeast (black). The error bars depict variation in two biological replicates. The equality of means was tested using the logarithm of the relative gene expression in two-sided t-tests, assuming equal variance. Observed p-values are shown under each pair (Data from free yeast is from [14]).

Mentions: The gene expression analysis supported the finding that the cells inside the capsules grown in furan aldehydes medium and hydrolysate were less stressed, or at least found the changes in stress level less challenging, compared to freely grown cells under similar conditions. The expression of the transcription factor YAP1 was relatively unchanged in the encapsulated cells in different media, with only a slightly higher level in hydrolysate medium (Figure 2A,B). However, the YAP1 expression level was increased due to encapsulation already in the medium without inhibitors (Figure 2A), indicating that the cells sense a stress as a direct or indirect consequence of being encapsulated. This could have been beneficial when transferred to an inhibitory medium since they, through the activation of the initial stress response, may be better prepared to cope with the increased stress posed by the inhibitors. The expression levels of ATR1 were higher in the encapsulated cells than in the free cells for all media (Figure 2C). However, the relative change in expression from the level in DGM was higher only in the case of carboxylic acids, against which the encapsulation did not provide significant protection (Figure 2D). The most prominent change due to the encapsulation was found in the expression of FLR1 in furan aldehydes medium (Figure 2E,F). The expression was only slightly increased in the encapsulated cells, whereas a large increase in expression was observed for the free cells. Also for this gene, the expression relative to TAF10 was higher in DGM in the encapsulated than in the free cells (Figure 2E), leading to less drastic increases in the encapsulated cells when subjected to inhibitory media (Figure 2F).


Encapsulation-induced stress helps Saccharomyces cerevisiae resist convertible Lignocellulose derived inhibitors.

Westman JO, Manikondu RB, Franzén CJ, Taherzadeh MJ - Int J Mol Sci (2012)

Gene expression in different media after two hours of anaerobic batch cultivations; (A, C and E) YAP1, ATR1 and FLR1 respectively, relative to the level of TAF10, (B, D and F) YAP1, ATR1 and FLR1 respectively, relative to the expression level in DGM, for free yeast (white) and encapsulated yeast (black). The error bars depict variation in two biological replicates. The equality of means was tested using the logarithm of the relative gene expression in two-sided t-tests, assuming equal variance. Observed p-values are shown under each pair (Data from free yeast is from [14]).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3472781&req=5

f2-ijms-13-11881: Gene expression in different media after two hours of anaerobic batch cultivations; (A, C and E) YAP1, ATR1 and FLR1 respectively, relative to the level of TAF10, (B, D and F) YAP1, ATR1 and FLR1 respectively, relative to the expression level in DGM, for free yeast (white) and encapsulated yeast (black). The error bars depict variation in two biological replicates. The equality of means was tested using the logarithm of the relative gene expression in two-sided t-tests, assuming equal variance. Observed p-values are shown under each pair (Data from free yeast is from [14]).
Mentions: The gene expression analysis supported the finding that the cells inside the capsules grown in furan aldehydes medium and hydrolysate were less stressed, or at least found the changes in stress level less challenging, compared to freely grown cells under similar conditions. The expression of the transcription factor YAP1 was relatively unchanged in the encapsulated cells in different media, with only a slightly higher level in hydrolysate medium (Figure 2A,B). However, the YAP1 expression level was increased due to encapsulation already in the medium without inhibitors (Figure 2A), indicating that the cells sense a stress as a direct or indirect consequence of being encapsulated. This could have been beneficial when transferred to an inhibitory medium since they, through the activation of the initial stress response, may be better prepared to cope with the increased stress posed by the inhibitors. The expression levels of ATR1 were higher in the encapsulated cells than in the free cells for all media (Figure 2C). However, the relative change in expression from the level in DGM was higher only in the case of carboxylic acids, against which the encapsulation did not provide significant protection (Figure 2D). The most prominent change due to the encapsulation was found in the expression of FLR1 in furan aldehydes medium (Figure 2E,F). The expression was only slightly increased in the encapsulated cells, whereas a large increase in expression was observed for the free cells. Also for this gene, the expression relative to TAF10 was higher in DGM in the encapsulated than in the free cells (Figure 2E), leading to less drastic increases in the encapsulated cells when subjected to inhibitory media (Figure 2F).

Bottom Line: It was shown that encapsulation increased the tolerance against readily convertible furan aldehyde inhibitors and to dilute acid spruce hydrolysate, but not to organic acid inhibitors that cannot be metabolized anaerobically.Gene expression analysis showed that the protective effect arising from the encapsulation is evident also on the transcriptome level, as the expression of the stress-related genes YAP1, ATR1 and FLR1 was induced upon encapsulation.The transcript levels were increased due to encapsulation already in the medium without added inhibitors, indicating that the cells sensed low stress level arising from the encapsulation itself.

View Article: PubMed Central - PubMed

Affiliation: School of Engineering, University of Borås, 501 90 Borås, Sweden; E-Mails: rameshmanikondu@hotmail.com (R.B.M.); mohammad.taherzadeh@hb.se (M.J.T.) ; Chemical and Biological Engineering-Industrial biotechnology, Chalmers University of Technology, 412 96 Göteborg, Sweden; E-Mail: franzen@chalmers.se.

ABSTRACT
The ability of macroencapsulated Saccharomyces cerevisiae CBS8066 to withstand readily and not readily in situ convertible lignocellulose-derived inhibitors was investigated in anaerobic batch cultivations. It was shown that encapsulation increased the tolerance against readily convertible furan aldehyde inhibitors and to dilute acid spruce hydrolysate, but not to organic acid inhibitors that cannot be metabolized anaerobically. Gene expression analysis showed that the protective effect arising from the encapsulation is evident also on the transcriptome level, as the expression of the stress-related genes YAP1, ATR1 and FLR1 was induced upon encapsulation. The transcript levels were increased due to encapsulation already in the medium without added inhibitors, indicating that the cells sensed low stress level arising from the encapsulation itself. We present a model, where the stress response is induced by nutrient limitation, that this helps the cells to cope with the increased stress added by a toxic medium, and that superficial cells in the capsules degrade convertible inhibitors, alleviating the inhibition for the cells deeper in the capsule.

Show MeSH
Related in: MedlinePlus