Effect of Ethanol Stress on Fermentation Performance of Saccharomyces cerevisiae Cells Immobilized on Nypa fruticans Leaf Sheath Pieces

Nguyen, Hoang Phong; Le, Hoang Du; Le, Van Viet Man

doi:10.17113/ftb.53.01.15.3617

Cited by 14 publications

(7 citation statements)

References 21 publications

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“…The decrease in mean cell size of yeast cells was greatest under an ethanol concentration 15% v/v, ranging from an average length of 6Á11 AE 0Á67 to 6Á74 AE 0Á66 µm and an average width of 3Á34 AE 0Á38 to 5Á21 AE 0Á53 µm. This morphological alteration may be caused by a change in the composition of fatty acid inside the cellular membrane, improving ethanol tolerance of the yeast (Nguyen et al 2015). However, effects of ethanol stress on the morphological changes of yeast cells remain unclear.…”

Section: Resultsmentioning

confidence: 99%

The ability of Pichia kudriavzevii to tolerate multiple stresses makes it promising for developing improved bioethanol production processes

Pongcharoen

2022

Letters in Applied Microbiology

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Thermotolerant ethanol fermenting yeasts have been extensively used in industrial bioethanol production. However, little is known about yeast physiology under stress during bioethanol processing. This study investigated the physiological characteristics of the thermotolerant yeast Pichia kudriavzevii, strains NUNS‐4, NUNS‐5 and NUNS‐6, under the multiple stresses of heat, ethanol and sodium chloride. Results showed that NUNS‐4, NUNS‐5 and NUNS‐6 displayed higher growth rates under each stress condition than the reference strain, Saccharomyces cerevisiae TISTR5606. Maximum specific growth rates under stresses of heat (45°C), 15% v/v ethanol and 1·0 M sodium chloride were 0·23 ± 0·04 (NUNS‐4), 0·11 ± 0·01 (NUNS‐5) and 0·15 ± 0·01 h–1 (NUNS‐5), respectively. Morphological features of all yeast studied changed distinctly with the production of granules and vacuoles when exposed to ethanol, and cells were elongated under increased sodium chloride concentration. This study suggests that the three P. kudriavzevii strains are potential candidates to use in industrial–scale fermentation due to a high specific growth rate under multiple stress conditions. Multiple stress‐tolerant P. kudriavzevii NUNS strains have received much attention not only for improving large‐scale fuel ethanol production, but also for utilizing these strains in other biotechnological industries.

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Section: Resultsmentioning

confidence: 99%

The ability of Pichia kudriavzevii to tolerate multiple stresses makes it promising for developing improved bioethanol production processes

Pongcharoen

2022

Letters in Applied Microbiology

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“…High accumulation of intracellular ethanol inhibits growth and disrupts the functions of proteins and enzymes, leading to membrane damage through alterations to cell membrane and cell wall compositions ( 24 , 29 ). High ethanol concentrations could also reduce sugar assimilation and inhibit the activity of glycolytic enzymes, causing slower sugar utilization and impairing fermentation ability ( 54 ). Since the production of the main precursors of cell membrane glycerol and fatty acids largely depends on Znf1 induction ( Fig.…”

Section: Discussionmentioning

confidence: 99%

Reprogramming of the Ethanol Stress Response in Saccharomyces cerevisiae by the Transcription Factor Znf1 and Its Effect on the Biosynthesis of Glycerol and Ethanol

Samakkarn

Soontorngun

2021

Appl Environ Microbiol

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High ethanol can severely inhibit the growth of yeast cells and fermentation productivity. The ethanologenic yeast Saccharomyces cerevisiae activates several well-defined cellular mechanisms of ethanol stress response (ESR); however, the involved regulatory control remains to be characterized. Here, we report a new transcription factor of ethanol stress adaptation called Znf1. It plays a central role in ESR by activating genes for glycerol and fatty acid production ( GUP1 , GPP1/2 , GPD1 , GAT1 , and OLE1 ) to preserve plasma membrane integrity. Importantly, Znf1 also activates genes implicated in cell wall biosynthesis ( FKS1 , SED1 , and SMI1 ) and the unfolded protein response ( HSP30/104 , KAR1 , and LHS1 ) to protect cells from proteotoxic stress. The znf1 Δ strain displays increased sensitivity to ethanol, ER-stressor β-mercaptoethanol, and cell wall-perturbing agent calcofluor white. To compensate for defective cell wall, the strain lacking ZNF1 or its target SMI1 displays increased glycerol levels of 16.4% and 29.2%, respectively. Znf1 collectively regulates an intricate network of target genes essential for growth, protein refolding, and production of key metabolites. Overexpression of ZNF1 not only confers tolerance to high ethanol but also increases ethanol production by 4.6% (8.43 g/L) or 2.8% (75.78 g/L) when using 2% or 20% (w/v) glucose as a substrate, respectively, compared to the wild-type strain. Mutually, stress-responsive transcription factors Msn2/4, Hsf1, and Yap1 are associated with some promoters of Znf1’s target genes to promote ethanol stress tolerance. In conclusion, this work has implicated the novel regulator Znf1 in coordinating expression of ESR genes and illuminates the unifying transcriptional reprogramming during alcoholic fermentation. IMPORTANCE The yeast S. cerevisiae is a major microbe widely used in food and non-food industries. However, accumulation of ethanol has a negative effect on its growth and limits ethanol production. Znf1 transcription factor has been implicated in utilization of different carbon sources, including glucose, the most abundant sugar on earth, and non-fermentable substrates, as a key regulator of glycolysis and gluconeogenesis. Here, role of Znf1 in ethanol stress response is defined. Znf1 actively reprograms expression of genes linked to UPR, heat shock response, glycerol and carbohydrate metabolism, and biosyntheses of cell membrane and cell wall components. A complex interplay among transcription factors of ESR indicates transcriptional fine-tuning as the main mechanism of stress adaptation, and Znf1 plays a major regulatory role in the coordination. Understanding the adaptive ethanol stress mechanism is crucial to engineering robust yeast strains for enhanced stress tolerance or increased ethanol production.

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“…According to the authors, increase in ethanol stress led to a decrease in unsaturated degree of fatty acid [21]. On the contrary, the unsaturation degree of membrane fatty acid of the immobilized yeast was nearly unchanged during the fermentation.…”

Section: Effect Of Acetic Acid On Substrate Assimilationmentioning

confidence: 99%

Effect of acetic acid on fermentation performance of the immobilized yeast Kluyveromyces marxianus on Nypa fruticans leaf sheath pieces

2016

Sci. Tech. Dev. J.

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The yeast cells of Kluyveromyces marxianus immobilized on Nypa fruticans leaf sheath pieces was tested for acetic acid tolerance during ethanol fermentation. Control sample with the free yeast cells were also performed under the same conditions. When the acetic acid content in the medium varied from 0 to 8g/L, the cell growth rate of the immobilized and free yeast decreased by 8.3 to 10.3 time, respectively. In addition, increase in acetic acid content from 0 to 8g/L reduced ethanol formation rate of the immobilized and free yeast by 4.1 to 6.8 times, respectively. The immobilized yeast always demonstrated faster sugar assimilation and higher final ethanol concentration than the free yeast. Under acetic acid stress, the fixed yeast exhibited less change in unsaturated degree of fatty acids in cellular membrane than the free yeast. Application of immobilized yeast was therefore potential for improvement in ethanol fermentation from lignocellulosic material.

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Effect of Ethanol Stress on Fermentation Performance of Saccharomyces cerevisiae Cells Immobilized on Nypa fruticans Leaf Sheath Pieces

Cited by 14 publications

References 21 publications

The ability of Pichia kudriavzevii to tolerate multiple stresses makes it promising for developing improved bioethanol production processes

The ability of Pichia kudriavzevii to tolerate multiple stresses makes it promising for developing improved bioethanol production processes

Reprogramming of the Ethanol Stress Response in Saccharomyces cerevisiae by the Transcription Factor Znf1 and Its Effect on the Biosynthesis of Glycerol and Ethanol

Effect of acetic acid on fermentation performance of the immobilized yeast Kluyveromyces marxianus on Nypa fruticans leaf sheath pieces

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