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1.
Bioresour Technol ; 339: 125578, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34298250

RESUMO

The full utilization of carbohydrates in lignocellulosic biomass is essential for an efficient biorefining process. In this study, co-fermentation was performed for processing ethanol and succinic from sugarcane bagasse. By optimizing the co-fermentation conditions, nutrition and feeding strategies, a novel process was developed to make full utilization of the glucose and xylose in the hydrolysate of sugarcane bagasse. The achieved concentrations of succinic acid and ethanol reached to 22.1 and 22.0 g/L, respectively, and could realize the conversion of 100 g SCB raw material into 8.6 g ethanol and 8.7 g succinic acid. It is worth mentioning that the CO2 released from S. cerevisiae in co-fermentation system was recycled by A. succinogenes to synthesize succinic acid, realized CO2 emission reduction in the process of lignocellulosic biomass biorefinery. This study provided a clue for efficient biorefinery of lignocellulosic biomass and reduction greenhouse gas emissions.


Assuntos
Saccharum , Dióxido de Carbono , Celulose , Etanol , Fermentação , Glucose , Pentoses , Saccharomyces cerevisiae , Ácido Succínico , Xilose
2.
Food Res Int ; 145: 110409, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34112412

RESUMO

Presently, because of the extraordinary roles and potential applications, rare sugars turn into a focus point for countless researchers in the field of carbohydrates. l-ribose and l-ribulose are rare sugars and isomers of each other. This aldo and ketopentose are expensive but can be utilized as an antecedent for the manufacturing of various rare sugars and l-nucleoside analogue. The bioconversion approach turns into an excellent alternative method to l-ribulose and l-ribose production, as compared to the complex and lengthy chemical methods. The basic purpose of this research was to describe the importance of rare sugars in various fields and their easy production by using enzymatic methods. l-Ribose isomerase (L-RI) is an enzyme discovered by Tsuyoshi Shimonishi and Ken Izumori in 1996 from Acinetobacter sp. strain DL-28. L-RI structure was cupin-type-ß-barrel shaped with a catalytic site between two ß-sheets surrounded by metal ions. The crystal structures of the L-RI showed that it contains a homotetramer structure. Current review have concentrated on the sources, characteristics, applications, conclusions and future prospects including the potentials of l-ribose isomerase for the commercial production of l-ribose and l-ribulose. The MmL-RIse and CrL-RIse have the potential to produce the l-ribulose up to 32% and 31%, respectively. The CrL-RIse is highly stable as compared to other L-RIs. The results explained that the L-RIs have great potential in the production of rare sugars especially, l-ribose and l-ribulose, while the immobilization technique can enhance its functionality and properties. The present study precises the applications of L-RIs acquired from various sources for l-ribose and l-ribulose production.


Assuntos
Aldose-Cetose Isomerases , Ribose , Pentoses
3.
Biomolecules ; 11(4)2021 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-33923608

RESUMO

A comparative study of the possibilities of using ribokinase → phosphopentomutase → nucleoside phosphorylase cascades in the synthesis of modified nucleosides was carried out. Recombinant phosphopentomutase from Thermus thermophilus HB27 was obtained for the first time: a strain producing a soluble form of the enzyme was created, and a method for its isolation and chromatographic purification was developed. It was shown that cascade syntheses of modified nucleosides can be carried out both by the mesophilic and thermophilic routes from D-pentoses: ribose, 2-deoxyribose, arabinose, xylose, and 2-deoxy-2-fluoroarabinose. The efficiency of 2-chloradenine nucleoside synthesis decreases in the following order: Rib (92), dRib (74), Ara (66), F-Ara (8), and Xyl (2%) in 30 min for mesophilic enzymes. For thermophilic enzymes: Rib (76), dRib (62), Ara (32), F-Ara (<1), and Xyl (2%) in 30 min. Upon incubation of the reaction mixtures for a day, the amounts of 2-chloroadenine riboside (thermophilic cascade), 2-deoxyribosides (both cascades), and arabinoside (mesophilic cascade) decreased roughly by half. The conversion of the base to 2-fluoroarabinosides and xylosides continued to increase in both cases and reached 20-40%. Four nucleosides were quantitatively produced by a cascade of enzymes from D-ribose and D-arabinose. The ribosides of 8-azaguanine (thermophilic cascade) and allopurinol (mesophilic cascade) were synthesized. For the first time, D-arabinosides of 2-chloro-6-methoxypurine and 2-fluoro-6-methoxypurine were synthesized using the mesophilic cascade. Despite the relatively small difference in temperatures when performing the cascade reactions (50 and 80 °C), the rate of product formation in the reactions with Escherichia coli enzymes was significantly higher. E. coli enzymes also provided a higher content of the target products in the reaction mixture. Therefore, they are more appropriate for use in the polyenzymatic synthesis of modified nucleosides.


Assuntos
Proteínas de Bactérias/metabolismo , Nucleosídeos/biossíntese , Pentosiltransferases/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Fosfotransferases/metabolismo , Thermus thermophilus/metabolismo , Escherichia coli/metabolismo , Pentoses/metabolismo , Thermus thermophilus/enzimologia
4.
FEMS Yeast Res ; 21(4)2021 05 10.
Artigo em Inglês | MEDLINE | ID: mdl-33890624

RESUMO

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.


Assuntos
Proteínas Fúngicas/metabolismo , Kluyveromyces/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Pentoses/metabolismo , Arabinose/metabolismo , Transporte Biológico , Xilose/metabolismo
5.
Metab Eng ; 64: 95-110, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33493644

RESUMO

Methanol is assimilated through the serine cycle to generate acetyl-CoA without carbon loss. However, a highly active serine cycle requires high consumption of reducing equivalents and ATP, thereby leading to the impaired efficiency of methanol conversion to reduced chemicals. In the present study, a genome-scale flux balance analysis (FBA) predicted that the introduction of the heterologous ribulose monophosphate (RuMP) cycle, a more energy-efficient pathway for methanol assimilation, could theoretically increase growth rate by 31.3% for the model alphaproteobacterial methylotroph Methylorubrum extorquens AM1. Based on this analysis, we constructed a novel synergistic assimilation pathway in vivo by incorporating the RuMP cycle into M. extroquens metabolism with the intrinsic serine cycle. We demonstrated that the operation of the synergistic pathway could increase cell growth rate by 16.5% and methanol consumption rate by 13.1%. This strategy rewired the central methylotrophic metabolism through adjusting core gene transcription, leading to a pool size increase of C2 to C5 central intermediates by 1.2- to 3.6-fold and an NADPH cofactor improvement by 1.3-fold. The titer of 3-hydroxypropionic acid (3-HP), a model product in the newly engineered chassis of M. extorquens AM1, was increased to 91.2 mg/L in shake-flask culture, representing a 3.1-fold increase compared with the control strain with only the serine cycle. The final titer of 3-HP was significantly improved to 0.857 g/L in the fed-batch bioreactor, which was more competitive compared with the other 3-HP producers using methane and CO2 as C1 sources. Collectively, our current study demonstrated that engineering the synergistic methanol assimilation pathway was a promising strategy to increase the carbon assimilation and the yields of reduced chemicals in diverse host strains for C1 microbial cell factories.


Assuntos
Metanol , Methylobacterium extorquens , Acetilcoenzima A , Methylobacterium extorquens/genética , Pentoses
6.
FEBS J ; 288(6): 1804-1808, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33063458

RESUMO

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.


Assuntos
Ácidos Graxos Voláteis , Prevotella , Fibras na Dieta , Humanos , Pentoses
7.
Bioresour Technol ; 320(Pt A): 124212, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33157450

RESUMO

Pentose-rich hydrolysate obtained from dilute acid pretreatment of oil palm empty fruit bunches was successfully consumed by pentose-consuming yeasts: Cyberlindnera jadinii (Cj) and Pichia jadinii (Pj). Nitrogen supplementation and no additional detoxification step were required. Pj produced 5.87 g/L of biomass using a C/N ratio of 14 after 120 h of fermentation, with xylose consumption of 71%. Cj produced 10.50 g/L of biomass after 96 h of fermentation with C/N ratio of 11.5, with maximum xylose consumption of 85%. ß-glucans, high value-added macromolecules, were further extracted from the yeast biomass, achieving yields of 3.1 and 3.0% from Pj and Cj, respectively. The isolated polysaccharides showed a chemical structure of ß-(1,3)-glucan with residues of other molecules. Additionally, ß-(1,6) branches seems to have been broken during isolation process. Further studies assessing ß-glucans production at industrial scale should be carried out looking for nitrogen sources and optimizing the ß-glucan isolation method.


Assuntos
Candida , beta-Glucanas , Biomassa , Fermentação , Frutas , Óleo de Palmeira , Pentoses
8.
FEBS J ; 288(6): 1839-1858, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-32770699

RESUMO

The microbial degradation of pentoses in the human gut is a crucial factor for the utilization of plant-based dietary fibers. A vast majority of gut microbes are able to use these C5-sugars as a carbon and energy source. However, the underlying metabolic pathways are not fully understood. Bioinformatic analysis showed that a large number of abundant gut bacteria lack genes encoding a transaldolase as a key enzyme of the pentose phosphate pathway. Among them was the important human gut microbe Prevotella copri, which was able to grow in minimal media containing xylose or hemicelluloses as the sole carbon source. Therefore, we looked for an alternative pathway for pentose conversion in P. copri using bioinformatics, enzyme activity assays, and the detection of intermediates of pentose metabolism. It became evident that the organism converted C5-sugars via the sedoheptulose-1,7-bisphosphate pathway (SBPP) to connect pentose metabolism with glycolysis. To circumvent the transaldolase reaction, P. copri uses the combined catalysis of a pyrophosphate-dependent phosphofructokinase and a fructose-bisphosphate aldolase. Furthermore, we present strong evidence that the SBPP is widely distributed in important gut bacteria, including members of the phyla Bacteroides, Firmicutes, Proteobacteria, Verrucomicrobia, and Lentisphaerae.


Assuntos
Bactérias/metabolismo , Fibras na Dieta/metabolismo , Trato Gastrointestinal/microbiologia , Via de Pentose Fosfato , Açúcares/metabolismo , Bactérias/genética , Biologia Computacional/métodos , Frutose-Bifosfato Aldolase/metabolismo , Glicólise , Humanos , Pentoses/metabolismo , Fosfotransferases/metabolismo , Polissacarídeos/metabolismo , Prevotella/enzimologia , Prevotella/genética , Prevotella/metabolismo , Fosfatos Açúcares/metabolismo , Transaldolase/genética , Transaldolase/metabolismo , Xilose/metabolismo
9.
Int J Biol Macromol ; 168: 558-571, 2021 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-33296692

RESUMO

L-Fuculose and D-ribulose are kinds of rare sugars used in food, agriculture, and medicine industries. These are pentoses and categorized into the two main groups, aldo pentoses and ketopentoses. There are 8 aldo- and 4 ketopentoses and only fewer are natural, while others are rare sugars found in a very small amount in nature. These sugars have great commercial applications, especially in many kinds of drugs in the medicine industry. The synthesis of these sugars is very expensive, difficult by chemical methods due to its absence in nature, and could not meet industry demands. The pentose izumoring strategy offers a complete enzymatic tactic to link all kinds of pentoses using different enzymes. The enzymatic production of L-fuculose and D-ribulose through L-fucose isomerase (L-FI) and D-arabinose isomerase (D-AI) is the inexpensive and uncomplicated method up till now. Both enzymes have similar kinds of isomerizing mechanisms and each enzyme can catalyze both L-fucose and D-arabinose. In this review article, the enzymatic process of biochemically characterized L-FI & D-AI, their application to produce L-fuculose and D-ribulose and its uses in food, agriculture, and medicine industries are reviewed.


Assuntos
Aldose-Cetose Isomerases/metabolismo , Hexoses/metabolismo , Pentoses/metabolismo , Agricultura , Indústria Alimentícia , Especificidade por Substrato
10.
Nat Commun ; 11(1): 6270, 2020 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-33293530

RESUMO

C-Analogues of the canonical N-nucleosides have considerable importance in medicinal chemistry and are promising building blocks of xenobiotic nucleic acids (XNA) in synthetic biology. Although well established for synthesis of N-nucleosides, biocatalytic methods are lacking in C-nucleoside synthetic chemistry. Here, we identify pseudouridine monophosphate C-glycosidase for selective 5-ß-C-glycosylation of uracil and derivatives thereof from pentose 5-phosphate (D-ribose, 2-deoxy-D-ribose, D-arabinose, D-xylose) substrates. Substrate requirements of the enzymatic reaction are consistent with a Mannich-like addition between the pyrimidine nucleobase and the iminium intermediate of enzyme (Lys166) and open-chain pentose 5-phosphate. ß-Elimination of the lysine and stereoselective ring closure give the product. We demonstrate phosphorylation-glycosylation cascade reactions for efficient, one-pot synthesis of C-nucleoside phosphates (yield: 33 - 94%) from unprotected sugar and nucleobase. We show incorporation of the enzymatically synthesized C-nucleotide triphosphates into nucleic acids by RNA polymerase. Collectively, these findings implement biocatalytic methodology for C-nucleotide synthesis which can facilitate XNA engineering for synthetic biology applications.


Assuntos
Glicosídeo Hidrolases/metabolismo , Ácidos Nucleicos/metabolismo , Biologia Sintética/métodos , Biocatálise , Glicosilação , Simulação de Acoplamento Molecular , Ácidos Nucleicos/química , Pentoses/química , Pentoses/metabolismo , Fosforilação , Pseudouridina/metabolismo , Uracila/química , Uracila/metabolismo , Xenobióticos/metabolismo
11.
J Ind Microbiol Biotechnol ; 47(12): 1173-1179, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33037458

RESUMO

The co-utilization of mixed (pentose/hexose) sugars constitutes a challenge for microbial fermentations. The fungus Ashbya gossypii, which is currently exploited for the industrial production of riboflavin, has been presented as an efficient biocatalyst for the production of biolipids using xylose-rich substrates. However, the utilization of xylose in A. gossypii is hindered by hexose sugars. Three A. gossypii homologs (AFL204C, AFL205C and AFL207C) of the yeast HXT genes that code for hexose transporters have been identified and characterized by gene-targeting approaches. Significant differences in the expression profile of the HXT homologs were found in response to different concentrations of sugars. More importantly, an amino acid replacement (N355V) in AFL205Cp, introduced by CRISPR/Cas9-mediated genomic edition, notably enhanced the utilization of xylose in the presence of glucose. Hence, the introduction of the afl205c-N355V allele in engineered strains of A. gossypii will further benefit the utilization of mixed sugars in this fungus.


Assuntos
Fermentação , Xilose , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Glucose/metabolismo , Proteínas de Transporte de Monossacarídeos/metabolismo , Pentoses , Xilose/metabolismo
12.
J Phys Chem B ; 124(45): 10117-10125, 2020 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-33112619

RESUMO

Rhamnogalacturonan II (RG-II)-the most complex polysaccharide known in nature-exists as a borate cross-linked dimer in the plant primary cell wall. Boric acid facilitates the formation of this cross-link on the apiosyl residues of RG-II's side chain A. Here, we detail the reaction mechanism for the cross-linking process with ab initio calculations coupled with transition state theory. We determine the formation of the first ester linkage to be the rate-limiting step of the mechanism. Our findings demonstrate that the regio- and stereospecific nature of subsequent steps in the reaction itinerary presents four distinct energetically plausible reaction pathways. This has significant implications for the overall structure of the cross-linked RG-II dimer assembly. Our transition state and reaction path analyses reveal key geometric insights that corroborate previous experimental hypotheses on borate ester formation reactions.


Assuntos
Ácidos Bóricos , Pectinas , Parede Celular , Pentoses
13.
Molecules ; 25(20)2020 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-33066073

RESUMO

In the last three decades, oligonucleotides have been extensively investigated as probes, molecular ligands and even catalysts within therapeutic and diagnostic applications. The narrow chemical repertoire of natural nucleic acids, however, imposes restrictions on the functional scope of oligonucleotides. Initial efforts to overcome this deficiency in chemical diversity included conservative modifications to the sugar-phosphate backbone or the pendant base groups and resulted in enhanced in vivo performance. More importantly, later work involving other modifications led to the realization of new functional characteristics beyond initial intended therapeutic and diagnostic prospects. These results have inspired the exploration of increasingly exotic chemistries highly divergent from the canonical nucleic acid chemical structure that possess unnatural physiochemical properties. In this review, the authors highlight recent developments in modified oligonucleotides and the thrust towards designing novel nucleic acid-based ligands and catalysts with specifically engineered functions inaccessible to natural oligonucleotides.


Assuntos
Aptâmeros de Nucleotídeos/química , Enzimas/química , Edição de Genes/métodos , Ácidos Nucleicos/química , Oligonucleotídeos Antissenso/química , Animais , Aptâmeros de Nucleotídeos/farmacologia , Pareamento de Bases , Carboidratos/química , Catálise , Enzimas/metabolismo , Humanos , Ligantes , Oligonucleotídeos/química , Pentoses/química
14.
Biochem Soc Trans ; 48(5): 2283-2293, 2020 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-32897293

RESUMO

Butanol is an important chemical and potential fuel. For more than 100 years, acetone-butanol-ethanol (ABE) fermentation of Clostridium strains has been the most successful process for biological butanol production. In recent years, other microbes have been engineered to produce butanol as well, among which Escherichia coli was the best one. Considering the crude oil price fluctuation, minimizing the cost of butanol production is of highest priority for its industrial application. Therefore, using cheaper feedstocks instead of pure sugars is an important project. In this review, we summarized butanol production from different renewable resources, such as industrial and food waste, lignocellulosic biomass, syngas and other renewable resources. This review will present the current progress in this field and provide insights for further engineering efforts on renewable butanol production.


Assuntos
Biocombustíveis , Butanóis/metabolismo , Engenharia Metabólica/métodos , Eliminação de Resíduos/métodos , Acetona/metabolismo , Biomassa , Biotecnologia/métodos , Butanóis/química , Carbono/química , Clostridium/metabolismo , Elétrons , Escherichia coli/metabolismo , Etanol/metabolismo , Fermentação , Alimentos , Hexoses/química , Hidrólise , Modelos Biológicos , Pentoses/química , Petróleo , Sacarose/química , Biologia Sintética
15.
Extremophiles ; 24(5): 759-772, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32761262

RESUMO

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.


Assuntos
Arabinose , Halobacteriaceae , Xilose , Arabinose/metabolismo , Bactérias , Halobacteriaceae/enzimologia , Pentoses , Ribose , Xilose/metabolismo
16.
Int J Biol Macromol ; 164: 1267-1274, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32750472

RESUMO

Recently, production of D-mannose becomes a hotspot owing to it exhibiting many physiological functions on people's health and wide applications in food and pharmaceutical field. The use of biological enzymes to production of D-mannose is of particular receiving considerable concerns due to it possessing many merits over chemical synthesis and plant extraction strategies. D-Lyxose isomerase (D-LIase) plays a pivotal role in preparation of D-mannose from d-fructose through isomerization reaction. Thus, a novel putative D-LIase from thermophiles strain Thermoprotei archaeon which was expressed in E. coli BL21(DE3) was first identified and biochemically characterized. The recombinant D-LIase showed an optimal temperature of 80 and 85 °C and pH of 6.5. It was highly thermostable at 70 °C and 80 °C after incubating for 48 h and 33 h, respectively, with retaining over 50% of the initial activity. A lower concentration of Ni2+ (0.5 mM) could greatly increase the activity by 25-fold, which was rare reported in other D-LIases. It was a dimer structure with melting temperature of 88.3 °C. Under the optimal conditions, 15.8 g L-1 of D-mannose and 33.8 g L-1 of D-xylulose were produced from 80 g L-1 of d-fructose and D-lyxose, respectively. This work provided a promising candidate sugar isomerase T. archaeon D-LIase for the production of D-mannose and D-xylulose.


Assuntos
Aldose-Cetose Isomerases/biossíntese , Archaea/enzimologia , Níquel/química , Proteínas Recombinantes/biossíntese , Tampões (Química) , Clonagem Molecular , Cristalização , Escherichia coli/metabolismo , Frutose/química , Concentração de Íons de Hidrogênio , Íons , Cinética , Manose/química , Peso Molecular , Pentoses/química , Fosfatos , Filogenia , Especificidade por Substrato , Temperatura
17.
Appl Biochem Biotechnol ; 192(3): 935-951, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32617845

RESUMO

L-Ribulose and L-ribose are two high-value unnatural sugars that can be biosynthesized by sugar isomerases. In this paper, an L-arabinose isomerase (BvAI) from Bacillus velezensis CICC 24777 was cloned and overexpressed in Escherichia coli BL21 (DE3) strain. The maximum activity of recombinant BvAI was observed at 45 °C and pH 8.0, in the presence of 1.0 mM Mn2+. Approximately 207.2 g/L L-ribulose was obtained from 300 g/L L-arabinose in 1.5 h by E. coli harboring BvAI. In addition, approximately 74.25 g/L L-ribose was produced from 300 g/L L-arabinose in 7 h by E. coli co-expressing BvAI and L-RI from Actinotalea fermentans ATCC 43279 (AfRI). This study provides a feasible approach for producing L-ribose from L-arabinose using a co-expression system harboring L-Al and L-RI.


Assuntos
Aldose-Cetose Isomerases/metabolismo , Bacillus/enzimologia , Pentoses/biossíntese , Ribose/biossíntese , Aldose-Cetose Isomerases/genética , Bacillus/metabolismo , Clonagem Molecular , Escherichia coli/genética , Expressão Gênica , Concentração de Íons de Hidrogênio , Temperatura
18.
Biomolecules ; 10(7)2020 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-32664266

RESUMO

A fluorometabolite, 5-fluoro-5-deoxy-D-ribulose (5-FDRul), from the culture broth of the soil bacterium Streptomyces sp. MA37, was identified through a combination of genetic manipulation, chemo-enzymatic synthesis and NMR comparison. Although 5-FDRul has been chemically synthesized before, it was not an intermediate or a shunt product in previous studies of fluorometalism in S. cattleya. Our study of MA37 demonstrates that 5-FDRul is a naturally occurring fluorometabolite, rendering it a new addition to this rare collection of natural products. The genetic inactivation of key biosynthetic genes involved in the fluorometabolisms in MA37 resulted in the increased accumulation of unidentified fluorometabolites as observed from 19F-NMR spectral comparison among the wild type (WT) of MA37 and the mutated variants, providing evidence of the presence of other new biosynthetic enzymes involved in the fluorometabolite pathway in MA37.


Assuntos
Vias Biossintéticas , Meios de Cultura/química , Mutação , Pentoses/análise , Streptomyces/crescimento & desenvolvimento , Proteínas de Bactérias/genética , Imagem por Ressonância Magnética de Flúor-19 , Halogenação , Família Multigênica , Pentoses/genética , Análise de Sequência de DNA , Microbiologia do Solo , Streptomyces/química , Streptomyces/genética
19.
J Microbiol ; 58(9): 725-733, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32583284

RESUMO

Phosphate sugar isomerases, catalyzing the isomerization between ketopentose/ketohexose phosphate and aldopentose/aldohexose phosphate, play an important role in microbial sugar metabolism. They are present in a wide range of microorganisms. They have attracted increasing research interest because of their broad substrate specificity and great potential in the enzymatic production of various rare sugars. Here, the enzymatic properties of various phosphate sugar isomerases are reviewed in terms of their substrate specificities and their applications in the production of valuable rare sugars because of their functions such as low-calorie sweeteners, bulking agents, and pharmaceutical precursor. Specifically, we focused on the industrial applications of D-ribose-5-phosphate isomerase and D-mannose-6-phosphate isomerase to produce D-allose and L-ribose, respectively.


Assuntos
Aldose-Cetose Isomerases/metabolismo , Bactérias/metabolismo , Glucose/biossíntese , Manose-6-Fosfato Isomerase/metabolismo , Ribose/biossíntese , Hexoses/metabolismo , Pentoses/metabolismo , Especificidade por Substrato , Edulcorantes/química
20.
Appl Microbiol Biotechnol ; 104(13): 5663-5672, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32372201

RESUMO

Currently, due to the special functions and potential application values, rare sugars become the hot topic in carbohydrate fields. L-Ribulose, an isomer of L-ribose, is an expensive rare ketopentose. As an important precursor for other rare sugars and L-nucleoside analogue synthesis, L-ribulose attracts more and more attention in recent days. Compared with complicated chemical synthesis, the bioconversion method becomes a good alternative approach to L-ribulose production. Generally, the bioconversion of L-ribulose was linked with ribitol, L-arabinose, L-ribose, L-xylulose, and L-arabitol. Herein, an overview of recent advances in the metabolic pathway, chemical synthesis, bioproduction of L-ribulose, and the potential application of L-ribulose is reviewed in detail in this paper. KEY POINTS: 1. L-Ribulose is a rare sugar and the key precursor for L-ribose production. 2. L-Ribulose is the starting material for L-nucleoside derivative synthesis. 3. Chemical synthesis, bioproduction, and applications of L-ribulose are reviewed.


Assuntos
Pentoses/metabolismo , Arabinose/metabolismo , Bactérias/classificação , Bactérias/metabolismo , Proteínas de Bactérias/metabolismo , Biocatálise , Biotransformação , Redes e Vias Metabólicas , Pentoses/síntese química , Ribitol/metabolismo , Ribose/metabolismo , Álcoois Açúcares/metabolismo , Xilulose/metabolismo
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