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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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Schematic figure of the hypothesized glucose and inhibitor concentration profiles in a cross section of the capsules in non-inhibitory medium (A) and medium with convertible inhibitors (B) and the corresponding differences in cell physiology. The numbers indicate different cell populations: 1. non starved cells; 2. slightly starvation-stressed cells with triggered ESR; 3. starved cells; 4. non-growing cells converting inhibitors; 5. ESR triggered cells, growing and converting inhibitors; 6. slightly starvation-stressed cells.
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f3-ijms-13-11881: Schematic figure of the hypothesized glucose and inhibitor concentration profiles in a cross section of the capsules in non-inhibitory medium (A) and medium with convertible inhibitors (B) and the corresponding differences in cell physiology. The numbers indicate different cell populations: 1. non starved cells; 2. slightly starvation-stressed cells with triggered ESR; 3. starved cells; 4. non-growing cells converting inhibitors; 5. ESR triggered cells, growing and converting inhibitors; 6. slightly starvation-stressed cells.

Mentions: Due to metabolism and mass transfer limitation, it can be visualized that the physiology of the cells inside a capsule changes, depending on their position along the radius of the cell pellet. In a non-inhibitory medium, superficial cells thrive while the interior cells suffer from nutrient limitation due to both mass transfer limitation and consumption, giving rise to a slight stress response. In a medium with readily convertible inhibitors, on the other hand, the cells close to the surface are forced to convert the inhibitors, leaving glucose for cells deeper in the cell pellet. Depending on the outer conditions, in this way there will be different parts of the capsule where cells thrive, as schematically depicted in Figure 3.


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

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

Schematic figure of the hypothesized glucose and inhibitor concentration profiles in a cross section of the capsules in non-inhibitory medium (A) and medium with convertible inhibitors (B) and the corresponding differences in cell physiology. The numbers indicate different cell populations: 1. non starved cells; 2. slightly starvation-stressed cells with triggered ESR; 3. starved cells; 4. non-growing cells converting inhibitors; 5. ESR triggered cells, growing and converting inhibitors; 6. slightly starvation-stressed cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3-ijms-13-11881: Schematic figure of the hypothesized glucose and inhibitor concentration profiles in a cross section of the capsules in non-inhibitory medium (A) and medium with convertible inhibitors (B) and the corresponding differences in cell physiology. The numbers indicate different cell populations: 1. non starved cells; 2. slightly starvation-stressed cells with triggered ESR; 3. starved cells; 4. non-growing cells converting inhibitors; 5. ESR triggered cells, growing and converting inhibitors; 6. slightly starvation-stressed cells.
Mentions: Due to metabolism and mass transfer limitation, it can be visualized that the physiology of the cells inside a capsule changes, depending on their position along the radius of the cell pellet. In a non-inhibitory medium, superficial cells thrive while the interior cells suffer from nutrient limitation due to both mass transfer limitation and consumption, giving rise to a slight stress response. In a medium with readily convertible inhibitors, on the other hand, the cells close to the surface are forced to convert the inhibitors, leaving glucose for cells deeper in the cell pellet. Depending on the outer conditions, in this way there will be different parts of the capsule where cells thrive, as schematically depicted in Figure 3.

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