The effects of the oxygen transfer coefficient and substrate concentration on the xylose fermentation by Debaryomyces hansenii

Roseiro, J. Carlos; Peito, M. Amália; Gı́rio, Francisco M.; Amaral-Collaço, M. T.

doi:10.1007/bf00245396

Cited by 105 publications

(29 citation statements)

References 17 publications

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“…Several researchers reported xylose to xylitol conversion by D. hansenii. 21–23 However, in all these reports, the concentration of initial xylose examined for xylitol production is much lower as compared to the present study.…”

Section: Discussioncontrasting

confidence: 70%

“…Our results were compared with the findings of Converti and coworkers21 who while working with D. hansenii NRRL Y‐7426 reported a lower xylitol volumetric productivity of 0.48 g/L h −1 and 0.39 g/L h −1 in presence of 200.0 gL −1 and 300 gL −1 of initial xylose concentration, respectively. Roseiro et al22 reported that a maximum xylitol yield of 0.53 gg −1 with a volumetric productivity of 1.12 g/L h −1 was achieved when D. hansenii DTIA‐77 was cultivated on lower concentration of 90 gL −1 of initial xylose. Similarly, Prakash et al35 also reported a lower xylose concentration of 100 gL −1 as optimal for xylitol production yielding 0.76 gg −1 with a volumetric productivity of 0.44 g/L h −1 , above this concentration, substrate inhibition was observed.…”

Section: Discussionmentioning

confidence: 99%

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Fermentation behavior of an osmotolerant yeast D. hansenii for Xylitol production

Misra

Raghuwanshi

Saxena

2012

Biotechnology Progress

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Realizing the importance of xylitol as a high-valued compound that serves as a sugar substitute, a new, one step thin layer chromatographic procedure for quick, reliable, and efficient determination of xylose and xylitol from their mixture was developed. Two hundred and twenty microorganisms from the laboratory stock cultures were screened for their ability to produce xylitol from D-xylose. Amongst these, an indigenous yeast isolate no.139 (SM-139) was selected and identified as Debaryomyces hansenii on the basis of morphological and biochemical characteristics and (26S) D1/D2 r DNA region sequencing. Debaryomyces hansenii produced 9.33 gL(-1) of xylitol in presence of 50.0 gL(-1) of xylose in 84 h at pH 5.5, 30°C, 200 rpm. In order to utilize even higher concentrations of xylose for maximum xylitol production, a xylose enrichment technique was developed. The strain of Debaryomyces hansenii was obtained through xylose enrichment technique in a statistically optimized medium containing 0.3% yeast extract, 0.2% peptone, 0.03% MgSO(4) .7H(2) O along with 1% methanol. The culture was inoculated with 6% inoculum and incubated at 30°C and 250 rpm. A yield of 0.6 gg(-1) was obtained with a xylitol volumetric productivity of 0.65 g/L h(-1) in the presence of 200 gL(-1) of xylose although up to 300 gL(-1) of xylose could be tolerated through batch fermentation. Through this technique, even higher concentrations of xylose as substrate could be potentially utilized for maximum xylitol production.

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Section: Discussioncontrasting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Fermentation behavior of an osmotolerant yeast D. hansenii for Xylitol production

Misra

Raghuwanshi

Saxena

2012

Biotechnology Progress

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“…Two important factors that must be considered when using immobilized cells are the carrier and the immobilization technique (12,16,17), an incorrect choice of which can provoke mass transfer limitations. Oxygen supply to the medium is by far the most important parameter influencing xylitol bioproduction (8,9,11,18), in that either excess or lack of this nutrient can impair the metabolism of pentose-fermenting yeasts. Thus, the effectiveness of immobilized-cell systems for xylose-to-xylitol bioconversion is expected to depend on the aeration control, which needs adequate aeration rates and appropriate carriers and bioreactors.…”

Section: Introductionmentioning

confidence: 99%

Xylitol Production from Sugarcane Bagasse Hydrolyzate in Fluidized Bed Reactor. Effect of Air Flowrate

Santos¹,

Carvalho²,

Silva³

et al. 2008

Biotechnol Progress

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Cells of Candida guilliermondii immobilized onto porous glass spheres were cultured batchwise in a fluidized bed bioreactor for xylitol production from sugarcane bagasse hemicellulose hydrolyzate. An aeration rate of only 25 mL/min ensured minimum yields of xylose consumption (0.60) and biomass production (0.14 g(DM)/g(Xyl)), as well as maximum xylitol yield (0.54 g(Xyt)/g(Xyl)) and ratio of immobilized to total cells (0.83). These results suggest that cell metabolism, although slow because of oxygen limitation, was mainly addressed to xylitol production. A progressive increase in the aeration rate up to 140 mL/min accelerated both xylose consumption (from 0.36 to 0.78 g(Xyl)/L.h) and xylitol formation (from 0.19 to 0.28 g(Xyt)/L.h) but caused the fraction of immobilized to total cells and the xylitol yield to decrease up to 0.22 and 0.36 g(Xyt)/g(Xyl), respectively. The highest xylitol concentration (17.0 g(Xyt)/L) was obtained at 70 mL/min, but the specific xylitol productivity and the xylitol yield were 43% and 22% lower than the corresponding values obtained at the lowest air flowrate, respectively. The concentrations of consumed substrates and formed products were used in material balances to evaluate the xylose fractions consumed by C. guilliermondii for xylitol production, complete oxidation through the hexose monophosphate shunt, and cell growth. The experimental data collected at variable oxygen level allowed estimating a P/O ratio of 1.35 mol(ATP)/mol(O) and overall ATP requirements for biomass growth and maintenance of 3.4 mol(ATP)/C-mol(DM).

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“…In fact, the air flowrate had a positive influence on the total cell concentration (Table 2), resulting in an average increase of 4.59 g/L in this response value. The deviation of the yeast metabolism from xylitol production to biomass formation has been reported by some authors (8, 14–16) and is related to coenzyme regeneration (4, 6).…”

Section: Resultsmentioning

confidence: 69%

Variables That Affect Xylitol Production from Sugarcane Bagasse Hydrolysate in a Zeolite Fluidized Bed Reactor

Santos¹,

Mussatto²,

Cunha³

et al. 2005

Biotechnology Progress

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The operational conditions for xylitol production by fermentation of sugarcane bagasse hydrolysate in a fluidized bed reactor with cells immobilized on zeolite were evaluated. Fermentations were carried out under different conditions of air flowrate (0.0125-0.0375 vvm), zeolite mass (100-200 g), initial pH (4-6), and xylose concentration (40-60 g/L), according to a 2(4) full factorial design. The air flowrate increase resulted in a metabolic deviation from product to biomass formation. On the other hand, the pH increase favored both the xylitol yield (Y(P/S)) and volumetric productivity (Q(P)), and the xylose concentration increase positively influenced the xylitol concentration. The best operational conditions evaluated were based on the use of an air flowrate of 0.0125 vvm, 100 g of zeolite, pH 6, and xylose concentration of 60 g/L. Under these conditions, 38.5 g/L of xylitol were obtained, with a Y(P/S) of 0.72 g/g, Q(P) of 0.32 g/L.h, and cell retention of 25.9%.

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The effects of the oxygen transfer coefficient and substrate concentration on the xylose fermentation by Debaryomyces hansenii

Cited by 105 publications

References 17 publications

Fermentation behavior of an osmotolerant yeast D. hansenii for Xylitol production

Fermentation behavior of an osmotolerant yeast D. hansenii for Xylitol production

Xylitol Production from Sugarcane Bagasse Hydrolyzate in Fluidized Bed Reactor. Effect of Air Flowrate

Variables That Affect Xylitol Production from Sugarcane Bagasse Hydrolysate in a Zeolite Fluidized Bed Reactor

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