Influence of oxygen transfer rate and media composition on fermentation ofd-xylose byPichia stipitis NRRL Y-7124

Guebel, Daniel V.; Cordenons, Alfredo; Nudel, B.C.; Giulietti, Ana María

doi:10.1007/bf01577657

Cited by 23 publications

(8 citation statements)

References 9 publications

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“…EMA was also used to assess the metabolic capabilities of S. stipitis for growth. Interestingly, no cell mass-producing pathways were found under anaerobic condition, which is consistent with the experiments that showed S. stipitis was unable to grow anaerobically but able to ferment glucose and/or xylose to ethanol (Skoog and Hahn-Hägerdal 1990;Guebel et al 1991). Under anaerobic culture conditions, the model predicted no function of mitochondria.…”

Section: Discussionsupporting

confidence: 90%

Metabolic pathway analysis of Scheffersomyces (Pichia) stipitis: effect of oxygen availability on ethanol synthesis and flux distributions

Unrean

Nguyen

2012

Appl Microbiol Biotechnol

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Elementary mode analysis (EMA) identifies all possible metabolic states of the cell metabolic network. Investigation of these states can provide a detailed insight into the underlying metabolism in the cell. In this study, the flux states of Scheffersomyces (Pichia) stipitis metabolism were examined. It was shown that increasing oxygen levels led to a decrease of ethanol synthesis. This trend was confirmed by experimental evaluation of S. stipitis in glucose-xylose fermentation. The oxygen transfer rate for an optimal ethanol production was 1.8 mmol/l/h, which gave the ethanol yield of 0.40 g/g and the ethanol productivity of 0.25 g/l/h. For a better understanding of the cell's regulatory mechanism in response to oxygenation levels, EMA was used to examine metabolic flux patterns under different oxygen levels. Up- and downregulation of enzymes in the network during the change of culturing condition from oxygen limitation to oxygen sufficiency were identified. The results indicated the flexibility of S. stipitis metabolism to cope with oxygen availability. In addition, relevant genetic targets towards improved ethanol-producing strains under all oxygenation levels were identified. These targeted genes limited the metabolic functionality of the cell to function according to the most efficient ethanol synthesis pathways. The presented approach is promising and can contribute to the development of culture optimization and strain engineers for improved lignocellulosic ethanol production by S. stipitis.

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Section: Discussionsupporting

confidence: 90%

Metabolic pathway analysis of Scheffersomyces (Pichia) stipitis: effect of oxygen availability on ethanol synthesis and flux distributions

Unrean

Nguyen

2012

Appl Microbiol Biotechnol

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“…With the same method, a q OUR ranging from 0.34 to 0.4 mmol O 2 /g CDW · h can be calculated for S. stiptis , which is very close to the value obtained with S. passalidarum . Our S. stipitis's q OUR values match some of the studies that were previously reported in the literature, which was about 0.3 mmol O 2 /g CDW · h for the xylose fermentation (Dellweg et al, ; Grootjen et al, ; Guebel et al, ; Laplace et al, ). Our numbers are higher than some reported from previous research, possibly because of differences in the sugar concentration (cf.…”

Section: Discussionsupporting

confidence: 88%

“…Several studies have tested oxygen transfer rates (OTR) ranging from 0.7 to 8.6 mmol O 2 /L h to understand the correlation between aeration and fermentation performance in native pentose fermenting yeasts (Du Preez ; Sreenath et al, ). An OTR ranging from 1.75 to 5 mmol/L h was reported as optimal for S. stipitis with 5% sugar (Grootjen et al, ; Guebel et al, ; Laplace et al, ). The optimal dissolved oxygen tension (DOT) of S. stipitis and S. shehatae less than 1% of saturation (about 0.08 mg/L = 2.5 µmol O 2 /L), which is below the detection limit of dissolved oxygen sensors, but even so, the physiological responses of these strains could be different at such low DOT levels (Dellweg et al, ; Du Preez et al, ).…”

Section: Introductionmentioning

confidence: 99%

Effects of aeration on growth, ethanol and polyol accumulation by Spathaspora passalidarum NRRL Y‐27907 and Scheffersomyces stipitis NRRL Y‐7124

Willis

Jeffries

2015

Biotech & Bioengineering

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Spathaspora passalidarum NN245 (NRRL-Y27907) is an ascomycetous yeast that displays a higher specific fermentation rate with xylose than with glucose. Previous studies have shown that its capacity for xylose fermentation increases while cell yield decreases with decreasing aeration. Aeration optimization plays a crucial role in maximizing bioethanol production from lignocellulosic hydrolysates. Here, we compared the kinetics of S. passalidarum NN245 and Scheffersomyces (Pichia) stipitis NRRL Y-7124 fermenting 15% glucose, 15% xylose, or 12% xylose plus 3% glucose under four different aeration conditions. The maximum specific fermentation rate for S. passalidarum was 0.153 g ethanol/g CDW · h with a yield of 0.448 g/g from 150 g/L xylose at an oxygen transfer rate of 2.47 mmol O2 /L h. Increasing the OTR to 4.27 mmol O2 /L h. decreased the ethanol yield from 0.46 to 0.42 g/g xylose while increasing volumetric ethanol productivity from 0.52 to 0.8 g/L h. Both yeasts had lower cells yields and higher ethanol yields when growing on xylose than when growing on glucose. Acetic acid accretions of both strains correlated positively with increasing aeration. S. passalidarum secreted lower amounts of polyols compared to S. stipitis under most circumstances. In addition, the composition of polyols differed: S. passalidarum accumulated mostly xylitol and R,R-2,3-butanediol (BD) whereas S. stipitis accumulated mostly xylitol and ribitol when cultivated in xylose or a mixture of 12% xylose and 3% glucose. R,R-2,3-BD accumulation by S. passalidarum during xylose fermentation can be as much as four times of that by S. stipitis, and R,R-2,3-BD is also the most abundant byproduct after xylitol. The ratios of polyols accumulated by the two species under different aeration conditions and the implications of these observations for strain and process engineering are discussed.

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“…The presence of biotin and thiamine improves the performance of P. stipitis markedly, although strains exist that can ferment xylose in the absence of all vitamins (Prior et al 1989). Recent work by Guebel et al (1991), however, shows that the supplemental addition of biotin and thiamine to a medium containing 5 giL yeast extract does not improve the xylose conversion performance of P. stipitis, whereas supplemental addition of trace elements does.…”

Section: Yeastmentioning

confidence: 98%

Xylose fermentation to ethanol. A review

McMillan¹

1993

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Influence of oxygen transfer rate and media composition on fermentation ofd-xylose byPichia stipitis NRRL Y-7124

Cited by 23 publications

References 9 publications

Metabolic pathway analysis of Scheffersomyces (Pichia) stipitis: effect of oxygen availability on ethanol synthesis and flux distributions

Metabolic pathway analysis of Scheffersomyces (Pichia) stipitis: effect of oxygen availability on ethanol synthesis and flux distributions

Effects of aeration on growth, ethanol and polyol accumulation by Spathaspora passalidarum NRRL Y‐27907 and Scheffersomyces stipitis NRRL Y‐7124

Xylose fermentation to ethanol. A review

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