Biosynthesis of xylitol by cell immobilization: an insight

Jain, Vasundhara; Awasthi, Aditi; Ghosh, Sanjoy

doi:10.1007/s13399-022-03724-2

Cited by 6 publications

(5 citation statements)

References 67 publications

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“…Several immobilization methods have been developed and tested over the years, differing in terms of the localization of cells with respect to the support and the nature of the microenvironment. These include adsorption on a support surface, mechanical containment behind a barrier, self-immobilization, and the physical entrapment in preformed porous support materials or hydrogels ( Jain et al, 2023 ). Among these techniques, the latter is one of the most widely explored.…”

Section: Introductionmentioning

confidence: 99%

Fermentative processes for the upcycling of xylose to xylitol by immobilized cells of Pichia fermentans WC1507

Ranieri,

Candeliere,

Moreno-García

et al. 2024

Front. Bioeng. Biotechnol.

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Xylitol is a pentose-polyol widely applied in the food and pharmaceutical industry. It can be produced from lignocellulosic biomass, valorizing second-generation feedstocks. Biotechnological production of xylitol requires scalable solutions suitable for industrial scale processes. Immobilized-cells systems offer numerous advantages. Although fungal pellet carriers have gained attention, their application in xylitol production remains unexplored. In this study, the yeast strain P. fermentans WC 1507 was employed for xylitol production. The optimal conditions were observed with free-cell cultures at pH above 3.5, low oxygenation, and medium containing (NH4)2SO4 and yeast extract as nitrogen sources (xylitol titer 79.4 g/L, YP/S 66.3%, and volumetric productivity 1.3 g/L/h). Yeast cells were immobilized using inactive Aspergillus oryzae pellet mycelial carrier (MC) and alginate beads (AB) and were tested in flasks over three consecutive production runs. Additionally, the effect of a 0.2% w/v alginate layer, coating the outer surface of the carriers (cMC and cAB, respectively), was examined. While YP/S values observed with both immobilized and free cells were similar, the immobilized cells exhibited lower final xylitol titer and volumetric productivity, likely due to mass transfer limitations. AB and cAB outperformed MC and cMC. The uncoated AB carriers were tested in a laboratory-scale airlift bioreactor, which demonstrated a progressive increase in xylitol production in a repeated batch process: in the third run, a xylitol titer of 63.0 g/L, YP/S of 61.5%, and volumetric productivity of 0.52 g/L/h were achieved. This study confirmed P. fermentans WC 1507 as a promising strain for xylitol production in both free- and entrapped-cells systems. Considering the performance of the wild strain, a metabolic engineering intervention aiming at further improving the efficiency of xylitol production could be justified. MC and AB proved to be viable supports for cell immobilization, but additional process development is necessary to identify the optimal bioreactor configuration and fermentation conditions.

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Section: Introductionmentioning

confidence: 99%

Fermentative processes for the upcycling of xylose to xylitol by immobilized cells of Pichia fermentans WC1507

Ranieri,

Candeliere,

Moreno-García

et al. 2024

Front. Bioeng. Biotechnol.

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“…Numerous techniques for immobilizing cells have been explored, including adsorption on a support surface, mechanical containment behind a barrier, self-immobilization, and entrapment in a porous matrix ( Jain et al, 2023 ). Among these approaches, the entrapment in a porous matrix, particularly using calcium alginate, has been extensively investigated due to its cost-effectiveness, straightforward bead preparation process, and mild operating conditions ( Clements et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Production of arabitol from glycerol by immobilized cells of Wickerhamomyces anomalus WC 1501

Ranieri,

Candeliere,

Sola

et al. 2024

Front. Bioeng. Biotechnol.

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Polyalcohols such as arabitol are among the main targets of biorefineries aiming to upcycle wastes and cheap substrates. In previous works Wickerhamomyces anomalus WC 1501 emerged as an excellent arabitol producer utilizing glycerol. Arabitol production by this strain is not growth associated, therefore, in this study, pre-grown cells were entrapped in calcium alginate beads (AB) and utilized for glycerol transformation to arabitol. Flasks experiments aimed to assess the medium composition (i.e., the concentration of inorganic and organic nitrogen sources and phosphates) and to establish the appropriate carrier-to-medium proportion. In flasks, under the best conditions of ammonium limitation and the carrier:medium ratio of 1:3 (w/v), 82.7 g/L glycerol were consumed in 168 h, yielding 31.2 g/L arabitol, with a conversion of 38% and volumetric productivity of 186 mg/mL/h. The process with immobilized cells was transferred to laboratory scale bioreactors with different configurations: stirred tank (STR), packed bed (PBR), fluidized bed (FBR), and airlift (ALR) bioreactors. The STR experienced oxygen limitation due to the need to maintain low stirring to preserve AB integrity and performed worse than flasks. Limitations in diffusion and mass transfer of oxygen and/or nutrients characterized also the PBR and the FBR and were partially relieved only in ALR, where 89.4 g/L glycerol were consumed in 168 h, yielding 38.1 g/L arabitol, with a conversion of 42% and volumetric productivity of 227 mg/mL/h. When the ALR was supplied with successive pulses of concentrated glycerol to replenish the glycerol as it was being consumed, 117 g/L arabitol were generated in 500 h, consuming a total of 285 g/L glycerol, with a 41% and 234 mg/L/h. The study strongly supports the potential of W. anomalus WC 1501 for efficient glycerol-to-arabitol conversion using immobilized cells. While the yeast shows promise by remaining viable and active for extended periods, further optimization is required, especially regarding mixing and oxygenation. Improving the stability of the immobilization process is also crucial for reusing pre-grown cells in multiple cycles, reducing dead times, biomass production costs, and enhancing the economic feasibility of the process.

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“…Industrial xylitol is currently produced through catalytic hydrogenation under high-pressure (up to 50 atm) and high-temperature (80-140 • C) conditions. This route has several disadvantages, including high operating and purification costs, high energy requirements, extensive purification and separation steps, and the generation of toxic byproducts [21]. In recent years, the biotechnological route for xylitol production has gained attention due to it having several advantages compared to the chemical route.…”

Section: Introductionmentioning

confidence: 99%

“…The biotechnological process for xylitol production is based on the conversion of biomass sources with xylitol-producing microorganisms under comparatively milder operating conditions. Furthermore, this bioprocess has a lower corrosive effect on reactors, releases fewer toxic by-products into the environment, and has a lower carbon footprint [21][22][23]. However, both second-generation ethanol and xylitol production still face several challenges related to efficient technologies for raw material pretreatment, hydrolysate fermentation, bioproduct recovery, and concerns regarding scale-up implementation [21,24].…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, this bioprocess has a lower corrosive effect on reactors, releases fewer toxic by-products into the environment, and has a lower carbon footprint [21][22][23]. However, both second-generation ethanol and xylitol production still face several challenges related to efficient technologies for raw material pretreatment, hydrolysate fermentation, bioproduct recovery, and concerns regarding scale-up implementation [21,24]. Therefore, novel techniques need to be studied to enable more feasible and efficient bioprocesses.…”

Section: Introductionmentioning

confidence: 99%

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Valorization of Corn Cobs for Xylitol and Bioethanol Production through Column Reactor Process

et al. 2023

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Corncobs are a plentiful lignocellulosic material that can be utilized for energy production as well as the generation of other high-value products. Within the modern concept of biorefineries, we present processes conducted in a column reactor for the valorization of corncobs as a substrate for ethanol and xylitol production. In the first step, corncobs were subjected to acid hydrolysis, resulting in a hemicellulosic hydrolysate rich in xylose sugars intended for xylitol production by Candida tropicalis UFMGBX12-a. The YP/S (yield coefficient of product to substrate) and QP (productivity) values were approximately 0.2 g/g and 0.15 g/L·h, respectively, for the assays conducted in the column reactor. Next, the remaining solid portion of cellulignin was used for ethanol production through semi-simultaneous saccharification and fermentation process by Scheffersomyces parashehatae UFMG-HM 52.2. This approach involved an intensified successive process consisting of alkaline pretreatment of cellulignin, followed by enzymatic hydrolysis and fermentative processes conducted in the same reactor without biomass transfer. After obtaining the enzymatic hydrolysate, a QP value of 0.4 g/L·h for ethanol production was observed in the fermentation process conducted in the column reactor. The results demonstrate the potential of corncobs as a carbon source for biomolecules production, utilizing a process conducive to scale-up.

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Biosynthesis of xylitol by cell immobilization: an insight

Cited by 6 publications

References 67 publications

Fermentative processes for the upcycling of xylose to xylitol by immobilized cells of Pichia fermentans WC1507

Fermentative processes for the upcycling of xylose to xylitol by immobilized cells of Pichia fermentans WC1507

Production of arabitol from glycerol by immobilized cells of Wickerhamomyces anomalus WC 1501

Valorization of Corn Cobs for Xylitol and Bioethanol Production through Column Reactor Process

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