One of the great advantages of microbial fermentation is the capacity to convert various carbon compounds into value-added chemicals. In this regard, there have been many efforts to engineer ...microorganisms to facilitate utilization of abundant carbon sources. Recently, the potential of acetate as a feedstock has been discovered; efforts have been made to produce various biochemicals from acetate based on understanding of its metabolism. In this review, we discuss the potential sources of acetate and summarized the recent progress to improve acetate utilization with microorganisms. Furthermore, we also describe representative studies that engineered microorganisms for the production of biochemicals from acetate.
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•Vapor-releasing method allows furfural to be easily separated from by-products.•The furfural yield of 73% was achieved in aqueous system without a catalyst.•Organic acids from ...hydrolysate works as catalysts for furfural production.•No purification of biomass hydrolysate is necessary for furfural production.
Biomass hydrolysate from autohydrolysis pretreatment was used for furfural production considering it is in rich of xylose, xylo-oligomers, and other decomposition products from hemicellulose structure. By using the vapor-releasing reactor system, furfural was protected from degradation by separating it from the reaction media. The maximum furfural yield of 73% was achieved at 200 °C for biomass hydrolysate without the use of the catalyst. This is because the presence of organic acids such as acetic acid in hydrolysate functioned as a catalyst. According to the results in this study, biomass hydrolysate with a vapor-releasing system proves to be efficient for furfural production. The biorefinery process which allows the separation of xylose-rich autohydrolysate from other parts from biomass feedstock also improves the overall application of the biomass.
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•A composite monolith adsorbent is fabricated by in-situ cryogelation in a needle hub.•Its hierarchical porous structure promotes the adsorption of furfural derivatives.•The monolith ...cryogel adsorbent provides good extraction recoveries.•The operation of the in-syringe device is simple and effective.•The fabricated adsorbent exhibits good reproducibility and reusability.
A porous composite monolith adsorbent of hyper-crosslinked polymer, graphene oxide and chitosan cryogel was fabricated for the extraction of furfural and 5-hydroxymethyl-furfural from cellulosic biomass hydrolysate. The composite adsorption materials synergistically enhanced the adsorption of furfural compounds and the porous chitosan cryogel helped to entrap and prevent the loss of the adsorbent composite. The composite monolith adsorbent was in-situ fabricated in a needle hub assembled with a disposable syringe performing in-syringe solid phase extraction. The extracted furfural compounds were quantified by high performance liquid chromatography. The fabricated adsorbent was characterized and the extraction conditions were optimized to achieve the best extraction recovery. In the optimum condition, the developed analytical approach provided linear from 1.0 to 50 ng/L for furfural and 0.5 to 50 ng/L for 5-hydroxymethyl-furfural, with respective detection limits of 0.25 ng/L and 0.20 ng/L. The developed approach was employed for the determination of furfural and 5-hydroxymethyl-furfural extracted from biomass hydrolysate of empty palm fruit bunch cellulose with satisfactory relative recoveries from 90.6 to 101.6 % with the RSDs below 6 %. The developed composite monolith adsorbent is easy to prepare and the extraction format is convenient to use. The good stability of the composite monolith adsorbent enabled reusability for 20 extraction-desorption cycles.
Biohydrogen production using renewable sources has been regarded as one of the most sustainable ways to develop low-cost and green production technology. In order to achieve this objective, herein ...biohydrogen production has been conducted using the combination of untreated secondary sewage sludge (Sss), algal biomass hydrolyzate (Abh), graphene oxide (GO) and bacterial consortia that forms a granular system. Thus, naturally formed granular system produced cumulative H2 of 1520 mL/L in 168 h with the maximum production rate of 13.4 mL/L/h in 96 h at initial pH 7.0, and optimum temperature of 37 °C. It is noticed that the combination of Abh, Sss and GO governed medium showed 42.05 % higher cumulative H2 production along with 22.71 % higher production rate as compared to Abh and Sss based H2 production medium. The strategy presented herein may find potential applications for the low-cost biohydrogen production using waste biomasses including Sss and Abh.
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•Aerobic granular sludge (AGS) is used to produce biohydrogen via dark fermentation.•AGS is based on sludge, algal biomass, bacterial consortia and graphene oxide (GO).•GO supported improved dark fermentative biohydrogen have been performed using AGS.•GO supported system showed 42.05 % higher cumulative H2 production compared to control.•Strategy may be highly potential to produce biohydrogen using waste biomass.
Integrated bioprocess strategies may facilitate ethanol production from both C6 and C5 fractions of lignocellulosic feedstocks. We propose a new process concept, SSICF, where sugarcane bagasse is ...hydrolyzed simultaneously with xylose isomerization and the co-fermentation of C6 and C5 sugars. A commercial cocktail was supplemented with our multi-enzymatic system composed of three recombinant enzymes immobilized in Feroxyhyte magnetic nanoparticles: β-glucosidase, β-xylosidase and xylose isomerase. SSICF was performed using non-GMO Saccharomyces at pH 6.0 and 35 °C for 72 h in a synthetic medium containing cellobiose and xylose, and another medium containing pretreated sugarcane bagasse (PSB). The results of ethanol global yields in SSICF were 77.67% and 73.24% for the synthetic medium and PSB, respectively. In a nutshell, this is the first report of a successful proof-of-concept of SSICF with four rounds of enzyme recycling and a non-GMO yeast, an innovative process with high potential for industrial use.
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•A new process concept was proposed for an efficient ethanol production in biorefineries.•The supplementation of immobilized enzymes in the SSICF process was investigated.•Non-GMO Saccharomyces was employed for second-generation ethanol production from PSB in SSICF.•The multi-enzymatic system allowed the yeast to produce ethanol from both C5/C6 sugars.•Ethanol production was achieved in all SSICF cycles with enzyme recycling.
Microbial production of xylonic acid can be achieved via xylose oxidation catalyzed by the xylose dehydrogenase enzyme. In the present study, 11 putative xylose dehydrogenases (XDH) from bacterial ...and fungi were identified through in silico analysis using the sequences of the two XDH previously described. Among them, 6 genes were successfully cloned and expressed in Komagataella phaffii (Pichia pastoris) as demonstrated by the ability of the strains to produce xylonic acid. The best strain was capable of producing up to 37.1 ± 1.9 and 11.7 ± 1.6 g/L of xylonic acid with yields of 0.96 ± 0.02 and 0.40 ± 0.06 g/g in mineral medium and sugarcane bagasse hydrolysate, respectively. The results presented here demonstrated the functionality of 6 newly identified xylose dehydrogenases, increasing the number of XDH described. In addition, the efficiency of K. phaffii as a xylonic acid producer is showed for the first time.
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•Six new XDHs were identified and functionally expressed in the yeast K. phaffii.•Recombinant strains were able to produce xylonic acid from renewable sugar.•0.96 g xylonic acid/g xylose was obtained in the bioreactor with the best strain.•Sugarcane bagasse hydrolysate were used as a substrate for xylonic acid production.•K. phaffii can be used as an efficient microbial platform to produce organic acids.
Lignocellulosic biomass provides attractive non-food carbohydrates for production of ethanol and dilute acid pretreatment is a biomass-independent process for access to these carbohydrates. However, ...this pretreatment also releases volatile and nonvolatile inhibitors of fermenting microorganisms. To identify unique gene products contributing to sensitivity/tolerance to non- volatile inhibitors, ethanologenic Escherichia coli strain LY180 was adapted for growth in vacuum-treated sugarcane bagasse acid hydrolysate (VBHz) lacking furfural and other volatile inhibitors. A mutant, strain AQ15, obtained after about 500 generations of growth in VBHz, grew and fermented the sugars in a medium with 50% VBHz. Comparative genome sequence analysis of strains AQ15 and LY180 revealed 95 mutations in strain AQ15. Six of these mutations were also found in strain SL112, an independent inhibitor-tolerant derivative of strain LY180. Among these six mutations, null mutations in mdh and bacA were identified as contributing factors to VBHz tolerance in strain AQ15, based on genetic and physiological analysis. Deletion of either gene in strain LY180 increased tolerance to VBHz from about 30% to 50% (v/v). Here, considering the location and physiological role of the two enzymes in the cell, it is likely that the two enzymes contribute to VBHz sensitivity of ethanologenic E. coli by different mechanisms.
The diversity in the chemical composition of lignocellulosic feedstocks can affect the conversion technologies employed for hydrogen production. Gasification and co–gasification activities of ...lignocellulosic biomass, biomass hydrolysate, and coal were evaluated for hydrogen rich gas production. The hydrolysates of biomass materials showed the best performance for gasification. The results indicated that biomass hydrolysates obtained from lignocellulosic biomass were more sensitive to degradation and therefore, produced more hydrogen and gaseous products than that of lignocellulosic biomass. The effects of feed (kenaf and sorghum hydrolysate), flow rate (0.3–2.0 mL/min) and temperature (700–900 °C) on hydrogen production and gasification yields were investigated. It was observed that 0.5 mL/min the optimum feed flow rate for the maximum total gas and hydrogen production. Synergism effects were observed for co–gasification of coal/biomass and coal/biomass hydrolysate. In all co–gasification processes, the main component of the gas mixture was hydrogen (≥70%).
•Hydrolysis of biomass is an efficient pretreatment for co-gasification with coal.•Biomass hydrolysates show better performance than raw biomasses in co-gasification.•Synergistic effects of co-gasification of coal/biomass hydrolysates were evaluated.•The main gas formed all co-gasification process was hydrogen (≥70%).•Co-gasification process is affected by feed flow rate of hydrolysate and temperature.
Cost effective bioethanol production from biomass requires complete utilization of mixed sugars and their efficient fermentation to ethanol. The fermenting strain should be capable of hexose and ...pentose utilization and tolerant to inhibitory byproducts of pretreatment. While, metabolic engineering strategies on Saccharomyces have yielded laboratory strains capable of mix sugar fermentation, hardly a few approaches have realized in industrial strains. Therefore, bioprospecting non-conventional native yeasts for efficient utilization of carbohydrate component of the biomass is imperative. In the present study, the fermentation efficiency of naturally pentose utilising yeasts such as Pichia stipitis NCIM3498, Pichia stipitis NCIM3497, Candida tropicalis Y6 and Rhodotorula glutinis Y1 was assessed on alkali pretreated rice straw hydrolysates, synthetic sugar/mixture and in presence of inhibitors. Highest fermentation efficiency (57.30%) on hydrolysate within 24 h was observed in P. stipitis NCIM3497 while P. stipitis NCIM3498 and C. tropicalis Y6 showed 53.03 and 46.51% respectively. On 2% glucose, fermentation efficiency was 64.77%–86.96% for Pichia and Candida strains, complete sugar depletion with 8.87 g L−1 highest ethanol production. On mixed sugars, highest fermentation efficiency was 87.35%. Pichia and Candida strains were tolerant to furfural and produced ethanol. Acetic acid and formic acid inhibited growth, sugar consumption and no ethanol detected.
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•Pichia stipitis, Candida tropicalis, Rhodotorula glutinis grew on straw hydrolysate.•P. stipitis NCIM3498 consumed >90% sugars producing 8.8 gL-1 ethanol on hydrolysate.•C. tropicalis Y6 used 57% sugars producing 2.84 gL-1 ethanol on straw hydrolysate.•P. stipitis NCIM3498 produced ∼4% ethanol in optimized synthetic mixed sugar medium.•Yeast strains were tolerant to furfural but inhibited by formic and acetic acid.
•Investigate adsorption equilibriums and mass transfer processes of monosaccharides.•Optimize operational conditions to separate monosaccharides in biomass hydrolysate.•Arabinose and xylose were ...recovered through cation resin chromatography.
Recovery of monosaccharides from hydrolysates of biomass wastes can bring environmental and economic benefits. This study aimed to explore the feasibility to separate major monosaccharides from hydrolysates of lignocellulosic biomass, i.e. glucose, xylose and arabinose by using column chromatography process. Cation exchange resin Amberlite IR120 and Amberlite IRP69 in Na+ and Ca2+ forms were chosen as adsorbents. The adsorption behaviors were firstly inspected by adsorption equilibrium and mass transfer coefficients. Then the optimal chromatography conditions were determined by using synthetic solution. Finally, hydrothermal liquefaction hydrolysate of pine branches was separated. The results showed that cation resin Amberlite IRP69 (Ca2+) had high adsorption selectivity for arabinose which could be recovered from synthetic solution with purity of 92%. The highest purity of 88% was achieved for xylose when using this resin to separate pretreated hydrolysate. This work suggests that cation exchange resin could be further developed for effective separation of monosaccharides mixture.
