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Biotechnology Journal Mar 2011Conversion of agricultural residues, energy crops and forest residues into bioethanol requires hydrolysis of the biomass and fermentation of the released sugars. During... (Review)
Review
Conversion of agricultural residues, energy crops and forest residues into bioethanol requires hydrolysis of the biomass and fermentation of the released sugars. During the hydrolysis of the hemicellulose fraction, substantial amounts of pentose sugars, in particular xylose, are released. Fermentation of these pentose sugars to ethanol by engineered Saccharomyces cerevisiae under industrial process conditions is the subject of this review. First, fermentation challenges originating from the main steps of ethanol production from lignocellulosic feedstocks are discussed, followed by genetic modifications that have been implemented in S. cerevisiae to obtain xylose and arabinose fermenting capacity per se. Finally, the fermentation of a real lignocellulosic medium is discussed in terms of inhibitory effects of furaldehydes, phenolics and weak acids and the presence of contaminating microbiota.
Topics: Arabinose; Ethanol; Fermentation; Genetic Engineering; Hydrolysis; Industrial Microbiology; Pentoses; Polysaccharides; Saccharomyces cerevisiae; Stress, Physiological; Xylose
PubMed: 21305697
DOI: 10.1002/biot.201000301 -
The FEBS Journal Mar 2021In the human gut, plant dietary fibers are broken down to hexoses (C6) and pentoses (C5) and subsequently fermented by gut bacteria, producing short-chain fatty acids...
In the human gut, plant dietary fibers are broken down to hexoses (C6) and pentoses (C5) and subsequently fermented by gut bacteria, producing short-chain fatty acids (SCFAs). The biochemistry of C5 metabolism has not been studied well in gut microorganisms. Garschagen et al. provide a new perspective in a detailed biochemical study on C5 metabolism of the abundant Prevotella copri, which uses the sedoheptulose-1,7-bisphosphate pathway instead of the pentose phosphate pathway.
Topics: Dietary Fiber; Fatty Acids, Volatile; Humans; Pentoses; Prevotella
PubMed: 33063458
DOI: 10.1111/febs.15575 -
The American Journal of Medicine May 1959
Topics: Carbohydrate Metabolism, Inborn Errors; Pentoses; Sugar Alcohol Dehydrogenases; Xylulose
PubMed: 13649698
DOI: 10.1016/0002-9343(59)90231-1 -
Advances in Biochemical... 2007The introduction of pentose utilization pathways in baker's yeast Saccharomyces cerevisiae is summarized together with metabolic engineering strategies to improve... (Review)
Review
The introduction of pentose utilization pathways in baker's yeast Saccharomyces cerevisiae is summarized together with metabolic engineering strategies to improve ethanolic pentose fermentation. Bacterial and fungal xylose and arabinose pathways have been expressed in S. cerevisiae but do not generally convey significant ethanolic fermentation traits to this yeast. A large number of rational metabolic engineering strategies directed among others toward sugar transport, initial pentose conversion, the pentose phosphate pathway, and the cellular redox metabolism have been exploited. The directed metabolic engineering approach has often been combined with random approaches including adaptation, mutagenesis, and hybridization. The knowledge gained about pentose fermentation in S. cerevisiae is primarily limited to genetically and physiologically well-characterized laboratory strains. The translation of this knowledge to strains performing in an industrial context is discussed.
Topics: Ethanol; Genetic Enhancement; Pentoses; Protein Engineering; Recombinant Proteins; Saccharomyces cerevisiae
PubMed: 17846723
DOI: 10.1007/10_2007_062 -
The Journal of Biological Chemistry Feb 2020The genomes of most cellulolytic clostridia do not contain genes annotated as transaldolase. Therefore, for assimilating pentose sugars or for generating C precursors...
The genomes of most cellulolytic clostridia do not contain genes annotated as transaldolase. Therefore, for assimilating pentose sugars or for generating C precursors (such as ribose) during growth on other (non-C) substrates, they must possess a pathway that connects pentose metabolism with the rest of metabolism. Here we provide evidence that for this connection cellulolytic clostridia rely on the sedoheptulose 1,7-bisphosphate (SBP) pathway, using pyrophosphate-dependent phosphofructokinase (PP-PFK) instead of transaldolase. In this reversible pathway, PFK converts sedoheptulose 7-phosphate (S7P) to SBP, after which fructose-bisphosphate aldolase cleaves SBP into dihydroxyacetone phosphate and erythrose 4-phosphate. We show that PP-PFKs of and C indeed can convert S7P to SBP, and have similar affinities for S7P and the canonical substrate fructose 6-phosphate (F6P). By contrast, (ATP-dependent) PfkA of , which does rely on transaldolase, had a very poor affinity for S7P. This indicates that the PP-PFK of cellulolytic clostridia has evolved the use of S7P. We further show that contains a significant SBP pool, an unusual metabolite that is elevated during growth on xylose, demonstrating its relevance for pentose assimilation. Last, we demonstrate that a second PFK of that operates with ATP and GTP exhibits unusual kinetics toward F6P, as it appears to have an extremely high degree of cooperative binding, resulting in a virtual on/off switch for substrate concentrations near its value. In summary, our results confirm the existence of an SBP pathway for pentose assimilation in cellulolytic clostridia.
Topics: Clostridiales; Clostridium thermocellum; Dihydroxyacetone Phosphate; Escherichia coli; Fructose-Bisphosphate Aldolase; Fructosephosphates; Kinetics; Pentose Phosphate Pathway; Pentoses; Phosphofructokinase-1; Phosphotransferases; Ribose; Sugar Phosphates; Transaldolase; Xylose
PubMed: 31871051
DOI: 10.1074/jbc.RA119.011239 -
Applied Microbiology and Biotechnology Jan 2012Corynebacterium glutamicum, the industrial microbe traditionally used for the production of amino acids, proved its value for the fermentative production of diverse... (Review)
Review
Corynebacterium glutamicum, the industrial microbe traditionally used for the production of amino acids, proved its value for the fermentative production of diverse products through genetic/metabolic engineering. A successful demonstration of the heterologous expression of arabinose and xylose utilization genes made them interesting biocatalysts for pentose fermentation, which are the main components in lignocellulosic hydrolysates. Its ability to withstand substantial amount of general growth inhibitors like furfurals, hydroxyl methyl furfurals and organic acids generated from the acid/alkali hydrolysis of lignocellulosics in growth arrested conditions and its ability to produce amino acids like glutamate and lysine in acid hydrolysates of rice straw and wheat bran, indicate the future prospective of this bacterium as a potent biocatalyst in fermentation biotechnology. However, the efforts so far on these lines have not yet been reviewed, and hence an attempt is made to look into the efficacy and prospects of C. glutamicum to utilize the normally non-fermentable pentose sugars from lignocellulosic biomass for the production of commodity chemicals.
Topics: Biotransformation; Corynebacterium glutamicum; Lignin; Metabolic Engineering; Pentoses; Plants
PubMed: 22094976
DOI: 10.1007/s00253-011-3686-4 -
Applied Biochemistry and Biotechnology 2004
Topics: Bacteria; Cellulose; Fungi; Lignin; Pentoses
PubMed: 15054228
DOI: 10.1007/978-1-59259-837-3_97 -
Extremophiles : Life Under Extreme... Sep 2020The degradation of the pentoses D-xylose, L-arabinose and D-ribose in the domain of archaea, in Haloferax volcanii and in Haloarcula and Sulfolobus species, has been...
The degradation of the pentoses D-xylose, L-arabinose and D-ribose in the domain of archaea, in Haloferax volcanii and in Haloarcula and Sulfolobus species, has been shown to proceed via oxidative pathways to generate α-ketoglutarate. Here, we report that the haloarchaeal Halorhabdus species utilize the bacterial-type non-oxidative degradation pathways for pentoses generating xylulose-5-phosphate. The genes of these pathways are each clustered and were constitutively expressed. Selected enzymes involved in D-xylose degradation, xylose isomerase and xylulokinase, and those involved in L-arabinose degradation, arabinose isomerase and ribulokinase, were characterized. Further, D-ribose degradation in Halorhabdus species involves ribokinase, ribose-5-phosphate isomerase and D-ribulose-5-phosphate-3-epimerase. Ribokinase of Halorhabdus tiamatea and ribose-5-phosphate isomerase of Halorhabdus utahensis were characterized. This is the first report of pentose degradation via the bacterial-type pathways in archaea, in Halorhabdus species that likely acquired these pathways from bacteria. The utilization of bacterial-type pathways of pentose degradation rather than the archaeal oxidative pathways generating α-ketoglutarate might be explained by an incomplete gluconeogenesis in Halorhabdus species preventing the utilization of α-ketoglutarate in the anabolism.
Topics: Arabinose; Bacteria; Halobacteriaceae; Pentoses; Ribose; Xylose
PubMed: 32761262
DOI: 10.1007/s00792-020-01192-y -
FEMS Yeast Research May 2021The capacity of yeasts to assimilate xylose or arabinose is strongly dependent on plasma membrane transport proteins. Because pentoses comprise a substantial proportion...
The capacity of yeasts to assimilate xylose or arabinose is strongly dependent on plasma membrane transport proteins. Because pentoses comprise a substantial proportion of available sugars in lignocellulosic hydrolysates, their utilisation is centrally important for the development of second generation biorefineries. Relatively few native pentose transporters have been studied and there is intense interest in expanding the repertoire. To aid the identification of novel transporters, we developed a screening platform in the native pentose-utilising yeast Kluyveromyces marxianus. This involved the targeted deletion of twelve transporters of the major facilitator superfamily (MFS) and application of a synthetic biology pipeline for rapid testing of candidate pentose transporters. Using this K. marxianus ΔPT platform, we identified several K. marxianus putative xylose or arabinose transporter proteins that recovered a null strain's ability to growth on these pentoses. Four proteins of the HGT-family were able to support growth in media with high or low concentrations of either xylose or arabinose, while six HXT-like proteins displayed growth only at high xylose concentrations, indicating solely low affinity transport activity. The study offers new insights into the evolution of sugar transporters in yeast and expands the set of native pentose transporters for future functional and biotechnological studies.
Topics: Arabinose; Biological Transport; Fungal Proteins; Kluyveromyces; Membrane Transport Proteins; Pentoses; Xylose
PubMed: 33890624
DOI: 10.1093/femsyr/foab026 -
Astrobiology Aug 2022The formose reaction has been a leading hypothesis for the prebiotic synthesis of sugars such as ribose for many decades but tends to produce complex mixtures of sugars...
The formose reaction has been a leading hypothesis for the prebiotic synthesis of sugars such as ribose for many decades but tends to produce complex mixtures of sugars and often tars. Channeling the formose reaction towards the synthesis of biologically useful sugars such as ribose has been a of origins-of-life research. Here, we tested the hypothesis that a simple, prebiotically plausible phosphorylating agent, acetyl phosphate, could direct the formose reaction towards ribose through phosphorylation of intermediates in a manner resembling gluconeogenesis and the pentose phosphate pathway. We did indeed find that addition of acetyl phosphate to a developing formose reaction stabilized pentoses, including ribose, such that after 5 h of reaction about 10-fold more ribose remained compared with control runs. But mechanistic analyses using liquid chromatography-mass spectrometry showed that, far from being directed towards ribose by phosphorylation, the formose reaction was halted by the precipitation of Ca ions as phosphate minerals such as apatite and hydroxyapatite. Adding orthophosphate had the same effect. Phosphorylated sugars were only detected below the limit of quantification when adding acetyl phosphate. Nonetheless, our findings are not strictly negative. The sensitivity of the formose reaction to geochemically reasonable conditions, combined with the apparent stability of ribose under these conditions, serves as a valuable constraint on possible pathways of sugar synthesis at the origin of life.
Topics: Mass Spectrometry; Pentoses; Phosphates; Ribose; Sugars
PubMed: 35833833
DOI: 10.1089/ast.2021.0125