RESUMO
Levan-type fructooligosaccharides (LFOS) exhibit significant biological activities and selectively promote the growth of certain beneficial bacteria. Levanase is an important enzyme for LFOS production. In this study, two isoforms of levanases, exo- and endo-type depolymerizing enzymes, from Bacillus subtilis HM7 isolated from Dynastes hercules larvae excrement were cloned, expressed, and characterized. The synergistic effect on the levan hydrolysis and kinetic properties of both isoforms were evaluated, indicating their cooperation in levan metabolism, where the endo-levanase catalyzes a rate-limiting step. In addition, homology models and molecular dynamics simulations revealed the key amino residues of the enzymes for levan binding and catalysis. It was found that both isoforms possessed distinct binding residues in the active sites, suggesting the importance of the specificity of the enzymes. Finally, we demonstrated the potential of endo-type levanase in LFOS synthesis using a one-pot reaction with levansucrase. Overall, this study fills the knowledge gap in understanding levanase's mechanism, making an important contribution to the fields of food science and biotechnology.
Assuntos
Bacillus subtilis , Glicosídeo Hidrolases , Oligossacarídeos , Bacillus subtilis/enzimologia , Oligossacarídeos/biossíntese , Oligossacarídeos/química , Glicosídeo Hidrolases/metabolismo , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/genética , Cinética , Frutanos/biossíntese , Frutanos/química , Hidrólise , Simulação de Dinâmica Molecular , Especificidade por Substrato , Hexosiltransferases/metabolismo , Hexosiltransferases/química , Hexosiltransferases/genética , CatáliseRESUMO
Levan, a ß-(2,6)-linked fructose polymer, exhibits diverse properties that impart versatility, rendering it a highly sought-after biopolymer with various industrial applications. Levan can be produced by various microorganisms using sucrose, food industry byproducts and agricultural wastes. Microbial levan represents the most potent cost-effective process for commercial-scale levan production. This study reviews the optimization of levan production by understanding its biosynthesis, physicochemical properties and the fermentation process. In addition, genetic and protein engineering for its increased production and emerging methods for its detection are introduced and discussed. All of these comprehensive studies could serve as powerful tools to optimize levan production and broaden its applications across various industries.
Assuntos
Fermentação , Frutanos , Frutanos/biossíntese , Frutanos/metabolismo , Bactérias/metabolismo , Bactérias/genética , Engenharia de Proteínas/métodos , Sacarose/metabolismo , Hexosiltransferases/metabolismo , Hexosiltransferases/genética , Microbiologia Industrial/métodosRESUMO
BACKGROUND: Fructans are water-soluble carbohydrates that accumulate in wheat and are thought to contribute to a pool of stored carbon reserves used in grain filling and tolerance to abiotic stress. RESULTS: In this study, transgenic wheat plants were engineered to overexpress a fusion of two fructan biosynthesis pathway genes, wheat sucrose: sucrose 1-fructosyltransferase (Ta1SST) and wheat sucrose: fructan 6-fructosyltransferase (Ta6SFT), regulated by a wheat ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (TaRbcS) gene promoter. We have shown that T4 generation transgene-homozygous single-copy events accumulated more fructan polymers in leaf, stem and grain when compared in the same tissues from transgene null lines. Under water-deficit (WD) conditions, transgenic wheat plants showed an increased accumulation of fructan polymers with a high degree of polymerisation (DP) when compared to non-transgenic plants. In wheat grain of a transgenic event, increased deposition of particular fructan polymers such as, DP4 was observed. CONCLUSIONS: This study demonstrated that the tissue-regulated expression of a gene fusion between Ta1SST and Ta6SFT resulted in modified fructan accumulation in transgenic wheat plants and was influenced by water-deficit stress conditions.
Assuntos
Proteínas de Bactérias , Frutanos , Hexosiltransferases , Plantas Geneticamente Modificadas , Triticum , Triticum/genética , Triticum/metabolismo , Plantas Geneticamente Modificadas/genética , Frutanos/metabolismo , Frutanos/biossíntese , Hexosiltransferases/genética , Hexosiltransferases/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , Fusão GênicaRESUMO
Fructans in angiosperms play essential roles in physiological functions and environmental adaptations. As a major source of industrial fructans (especially inulin-type), chicory (Cichorium intybus L.) is a model species for studying fructan biosynthesis. However, the genes underlying this process and their evolutionary history in angiosperms remain elusive. We combined multiple sequencing technologies to assemble and annotate the chicory genome and scan its (epi)genomic features, such as genomic components, DNA methylation, and three-dimensional (3D) structure. We also performed a comparative genomics analysis to uncover the associations between key traits and gene families. We achieved a nearly complete chicory genome assembly and found that continuous bursts of a few highly active retrotransposon families largely shaped the (epi)genomic characteristics. The highly methylated genome with its unique 3D structure potentially influences critical biological processes. Our comprehensive comparative genomics analysis deciphered the genetic basis for the rich sesquiterpene content in chicory and indicated that the fructan-accumulating trait resulted from convergent evolution in angiosperms due to shifts in critical sites of fructan-active enzymes. The highly characterized chicory genome provides insight into Asteraceae evolution and fructan biosynthesis in angiosperms.
Assuntos
Cichorium intybus , Frutanos , Magnoliopsida , Asteraceae/genética , Metabolismo dos Carboidratos , Cichorium intybus/genética , Frutanos/biossíntese , Magnoliopsida/genéticaRESUMO
Levan is a high-valued polysaccharide of fructose produced by several microbial species. These polysaccharides have been described as effective therapeutic agents in some human disease conditions, such as cancer, heart diseases and diabetes. The objective of this study was to examine the effect of levan (ß-(2 â 6)-fructan) produced through sucrose fermentation by B. subtilis var. natto on the proliferation rate, cytotoxicity, and apoptosis of human neuroblastoma SH-SY5Y cells. It was obtained 41.44 g/L of levan in 18 h by biotechnological fermentation and SH-SY5Y cells were exposed to 1000 µg/mL of levan. The treatment with 1000 µg/mL of levan induced apoptosis in SH-SY5Y cancer cells by the significant increase in Annexin V/7-AAD and caspase 3/7 activation, but did not decrease proliferation or triggered a cytotoxic effect. 1000 µg/mL levan treatment is a promising therapeutic strategy for SH-SY5Y neuroblastoma cells.
Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Bacillus subtilis/metabolismo , Frutanos/farmacologia , Antineoplásicos/química , Antineoplásicos/metabolismo , Caspase 3/metabolismo , Caspase 7/metabolismo , Linhagem Celular Tumoral , Frutanos/biossíntese , Frutanos/química , HumanosRESUMO
Background: Levan or fructan, a polysaccharide of fructose, is widely used in various commercial industries. Levan could be produced by many organisms, including plants and bacteria. The cloning of the gene from Bacillus licheniformis, which expressed levansucrase in Escherichia coli host, was carried out successfully. In the present study, we performed the in vitro production of levan and analyzed its potential application as antibacterial and antioxidant agents. Methods: In vitro levan production catalyzed by heterologous-expressed levansucrase Lsbl-bk1 and Lsbl-bk2 was optimized with Box-Wilson design. The antibacterial activity of the produced levan was carried out using agar well diffusion method, while its antioxidant activity was tested by free radical scavenging assays. Results: The optimum conditions for levan production were observed at 36 °C and pH 7 in 12% (w/v) sucrose for levansucrase Lsbl-bk1, while the optimum catalysis of levansucrase Lsbl-bk2 was obtained at 32 oC and pH 8 in the same sucrose concentration. The in vitro synthesized levan showed an antibacterial activity within a concentration range of 10-20% (w/v) against Staphylococcus aureus, E. coli, and Pseudomonas aeruginosa. The same levan was also able to inhibit the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity with the antioxidant strength of 75% compared to ascorbic acid inhibition. Conclusion: Our study, therefore, shows that the optimized heterologous expression of levansucrases encoded by Lsbl-bk1 and Lsbl-bk2 could open the way for industrial levan production as an antibacterial and antioxidant agent.
Assuntos
Antibacterianos/farmacologia , Antioxidantes/farmacologia , Frutanos/biossíntese , Frutanos/farmacologia , Modelos Moleculares , Análise de Variância , Ácido Ascórbico/farmacologia , Bactérias/efeitos dos fármacos , Frutanos/química , Testes de Sensibilidade Microbiana , TermogravimetriaRESUMO
Fructan based biopolymers have been extensively characterized and explored for their potential applications. Linear chained biopolymers, like levan-type fructan, have gained attention because they have exhibited unconventional stretchable and unbendable properties along with biodegradable and biocompatible nature. Current study deals with the chemical characterization and cytotoxic analysis of fructose based exopolysaccharide that was extracellularly produced by an indigenously isolated bacterial species (Zymomonas mobilis KIBGE-IB14). Maximum yield of exopolysaccharide (44.7 gL-1) was attained after 72 h of incubation at 30 °C under shaking conditions (180 rpm) when the culture medium was supplemented with 150.0 gL-1 of sucrose as a sole carbon source. This exopolysaccharide displayed high water solubility index (96.0%) with low water holding capacity (17.0%) and an intrinsic viscosity of about 0.447 dL g-1. This biopolymer exhibited a characteristic linear homopolysaccharide structure of levan when characterized using Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (NMR) spectroscopy (1H, 13C, TOCSY and NOESY) while, Atomic Force Microscopy (AFM) revealed its pointed and thorny structure. The decomposition temperature of levan was approximately 245 °C as revealed by Thermal Gravimetric Analysis (TGA). X-Ray Diffraction (XRD) results revealed its amorphous nature with crystalline phase. Cytotoxicity of different concentrations of levan was investigated against mouse fibroblast cell lines by measuring their cellular metabolic activity and it was noticed that a higher concentration of levan (2.0 mg ml-1) permitted the normal cell growth of NIH/3T3 cell lines. This non-cytotoxic and biocompatible nature suggests that this levan has the capability to be utilized in food and drug-based formulations as it exhibited biomedical potential.
Assuntos
Biopolímeros/farmacologia , Frutanos/farmacologia , Zymomonas/química , Animais , Biopolímeros/biossíntese , Biopolímeros/química , Configuração de Carboidratos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Frutanos/biossíntese , Frutanos/química , Camundongos , Células NIH 3T3 , Zymomonas/metabolismoRESUMO
The synthesis of complex oligosaccharides is desired for their potential as prebiotics, and their role in the pharmaceutical and food industry. Levansucrase (LS, EC 2.4.1.10), a fructosyl-transferase, can catalyze the synthesis of these compounds. LS acquires a fructosyl residue from a donor molecule and performs a non-Lenoir transfer to an acceptor molecule, via ß-(2â6)-glycosidic linkages. Genome mining was used to uncover new LS enzymes with increased transfructosylating activity and wider acceptor promiscuity, with an initial screening revealing five LS enzymes. The product profiles and activities of these enzymes were examined after their incubation with sucrose. Alternate acceptor molecules were also incubated with the enzymes to study their consumption. LSs from Gluconobacter oxydans and Novosphingobium aromaticivorans synthesized fructooligosaccharides (FOSs) with up to 13 units in length. Alignment of their amino acid sequences and substrate docking with homology models identified structural elements causing differences in their product spectra. Raffinose, over sucrose, was the preferred donor molecule for the LS from Vibrio natriegens, N. aromaticivorans, and Paraburkolderia graminis. The LSs examined were found to have wide acceptor promiscuity, utilizing monosaccharides, disaccharides, and two alcohols to a high degree.
Assuntos
Frutanos/química , Frutose/química , Gluconobacter oxydans/enzimologia , Hexosiltransferases/química , Oligossacarídeos/química , Sphingomonadaceae/enzimologia , Sequência de Aminoácidos , Sítios de Ligação , Biocatálise , Burkholderiaceae/química , Burkholderiaceae/enzimologia , Frutanos/biossíntese , Frutose/metabolismo , Expressão Gênica , Gluconobacter oxydans/química , Hexosiltransferases/genética , Hexosiltransferases/metabolismo , Humanos , Cinética , Simulação de Acoplamento Molecular , Oligossacarídeos/biossíntese , Prebióticos/análise , Ligação Proteica , Conformação Proteica , Rafinose/química , Rafinose/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Sphingomonadaceae/química , Homologia Estrutural de Proteína , Especificidade por Substrato , Sacarose/química , Sacarose/metabolismo , Vibrio/química , Vibrio/enzimologiaRESUMO
Fructan exohydrolases (FEHs) are structurally related to cell wall invertases. While the latter are ubiquitous in higher plants, the role of FEHs in non-fructan species has remained enigmatic. To explore possible roles of FEHs in maize, a full length putative Zm-6-FEH-encoding cDNA was cloned displaying high sequence similarity with cell wall invertases. For functional characterization, Zm-6-FEH protein was expressed in Picha pastoris and in Nicotiana benthamiana leaves. Enzyme activity of recombinant Zm-6-FEH protein showed a strong preference for levan as substrate. Expression profiling in maize seedlings revealed higher transcript amounts in the more mature leaf parts as compared to the growth zone at the base of the leaf, in good correlation with FEH enzyme activities. Subcellular localization analysis indicated Zm-6-FEH location in the apoplast. Noteworthy, incubation of leaf discs with levan and co-incubation with high levan-producing bacteria selectively up-regulated transcript levels of Zm-6-FEH, accompanied by an increase of 6-FEH enzyme activity. In summary, the results indicate that Zm-6-FEH, a novel fructan exohydrolase of a non-fructan species, may have a role in plant defense against levan-producing bacteria.
Assuntos
Bactérias/metabolismo , Frutanos/química , Hidrolases/química , Zea mays/química , Sequência de Aminoácidos , Bactérias/enzimologia , Carboidratos/química , Carboidratos/isolamento & purificação , Clonagem Molecular , Expressão Ectópica do Gene , Frutanos/biossíntese , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Filogenia , Folhas de Planta , Estresse Fisiológico , Transcriptoma , Zea mays/classificação , Zea mays/genéticaRESUMO
Levan, a ß-2,6-glycosidic linked fructan, is a promising alternative for the inulin dominated fructan market. Although levan is already used in some cosmetic products, the commercial availability of the fructan is still limited. Here we show that Gluconobacter japonicus LMG 1417 is a potent levan-forming organism and a promising platform for the industrial production of levan. The levansucrase LevS1417, which is produced by G. japonicus LMG 1417 and secreted by a signal-peptide-independent pathway, exhibited extraordinary high activity (4726⯱â¯821â¯Uâ¯mg-1 at 50⯰C). A cell-free levan production based on the supernatant of the investigated strain led to a final levan yield of 157.9⯱â¯7.6â¯gâ¯L-1. The amount of secreted levansucrase was more than doubled by plasmid-mediated homologous overproduction of LevS1417 in G. japonicus LMG 1417. Accordingly, the space-time yield of cell-free levan production was doubled using the plasmid-bearing mutant.
Assuntos
Frutanos/biossíntese , Gluconobacter/metabolismo , Fracionamento Químico , Cromatografia Líquida de Alta Pressão , Fibras na Dieta , Ativação Enzimática , Escherichia coli , Frutanos/isolamento & purificação , Expressão Gênica , Gluconobacter/enzimologia , Hexosiltransferases/metabolismo , Cinética , Espectroscopia de Ressonância Magnética , Plasmídeos/genética , Prebióticos , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Levan is a fructose polymer with ß-(2 â 6) glycosidic linkages. It is produced by several microorganisms, and due to its potential biotechnological and industrial applications, various levan-producing bacteria with different levels of production efficiencies have been reported. We investigated the levan-producing ability of the acetic acid bacterium, Tanticharoenia sakaeratensis. The exopolysaccharides produced by the bacterium under a sucrose environment were characterized as levan by FT-IR, and 1H and 13C NMR. The molecular weight of levan thus produced range from 1.0 × 105-6.8 × 105 Da. The maximum yield of levan from T. sakaeratensis is 24.7 g·L-1 in a liquid medium containing 20% (w/v) sucrose and incubated at 37 °C, 250 RPM for 35 h. The levan produced by T. sakaeratensis can promote nitric oxide production in RAW264.7 macrophage cells in a concentration-dependent manner, suggesting it has immunomodulatory effects. Our study reveals that T. sakaeratensis can be potentially employed as a new source of levan for industrial applications.
Assuntos
Acetobacteraceae/metabolismo , Frutanos/biossíntese , Frutanos/farmacologia , Fatores Imunológicos/biossíntese , Fatores Imunológicos/farmacologia , Acetobacteraceae/imunologia , Animais , Sobrevivência Celular/efeitos dos fármacos , Fermentação , Frutanos/química , Fatores Imunológicos/química , Espectroscopia de Ressonância Magnética , Camundongos , Peso Molecular , Óxido Nítrico/metabolismo , Células RAW 264.7 , Sacarose/metabolismoRESUMO
Levan-typed fructooligosaccharide (LFOS), a ß-2,6 linked oligofructose, displays the potential application as a prebiotic and therapeutic dietary supplement. In the present study, LFOS was synthesized using levansucrase from Bacillus amyloliquefaciens KK9 (LsKK9). The wild-type LsKK9 was cloned and expressed in E. coli, and purified by cation exchanger chromatography. Additionally, Y237S variant of LsKK9 was constructed based on sequence alignment and structural analysis to enhance the LFOS production. High-performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD) analysis indicated that Y237S variant efficiently produced a higher amount of short-chain LFOS than wild type. Also, the concentration of enzyme and sucrose in the reactions was optimized. Finally, prebiotic activity assay demonstrated that LFOS produced by Y237S variant had higher prebiotic activity than that of the wild-type enzyme, making the variant enzyme attractive for food biotechnology.
Assuntos
Bacillus amyloliquefaciens/enzimologia , Proteínas de Bactérias/metabolismo , Frutanos/biossíntese , Hexosiltransferases/metabolismo , Mutação de Sentido Incorreto , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Domínio Catalítico , Hexosiltransferases/química , Hexosiltransferases/genética , Microbiologia Industrial/métodos , Prebióticos , Engenharia de Proteínas/métodosRESUMO
Here, two kinds of polysaccharide-based biocomposites were investigated. The enzymatically synthesized levan from Erwinia amylovora was applied as the matrix, while montmorillonite clay and bovine serum albumin (BSA) were used as additive in the biocomposite. To examine the properties of levan/MMT biocomposite, we choose different ratios between levan and MMT to implement the surface morphology observation, thermal property analysis, and rheological behavior determination. As a result, the levan/MMT biocomposite in a 2:1 blending ratio showed a significant improvement both in the thermal and rheological properties. Meanwhile, the 0.1 % levan/BSA nanoparticle showed the highest encapsulation capacity and surface charge as 53.13⯱â¯2.64 % and +3.92⯱â¯0.43â¯mV. Last but not least, the levan/BSA nanoparticle exhibited a slower and controlled release of the BSA from the system. All of these results indicated a potential application of levan-based biocomposite and nanoparticle.
Assuntos
Bentonita/química , Materiais Biocompatíveis/química , Frutanos/química , Nanopartículas/química , Soroalbumina Bovina/química , Animais , Materiais Biocompatíveis/síntese química , Bovinos , Erwinia amylovora/enzimologia , Frutanos/biossíntese , Hexosiltransferases/metabolismo , Tamanho da Partícula , Proteínas Recombinantes/metabolismo , Propriedades de SuperfícieRESUMO
Differences between the levan obtained from bacteria and from cell-free systems were studied in this work. Results showed that both polymers are non-porous solids (type II isotherm with 20 m2/g) with a main thermal decomposition at 200⯰C and a negligible value of protein adsorption. Microbial levan produced nanoparticles of 90â¯nm in diameter whereas nanoparticles of 110â¯nm were obtained with the polymer obtained from a cell-free system. Both polymers behave as aggregates depending on the critical aggregation concentration. At the same time, that concentration depends on the technique used for the polymer synthesis. Cell-free system aggregation concentration is 0.24â¯mg/mL whereas a concentration of 0.05â¯mg/mL was found for the microbial system. In both cases, the average molecular weight of the aggregate is higher than 2000â¯kDa. These results highlight the existence of aggregation equilibrium for both polymers that has to be taken into account for future applications.
Assuntos
Acinetobacter/metabolismo , Sistema Livre de Células/metabolismo , Frutanos/biossíntese , Frutanos/química , Nanopartículas/química , Tamanho da PartículaRESUMO
Levan is a fructose polymer with diverse applications in the food and medical industries. In this study, levansucrase from Rahnella aquatilis (RaLsrA) was hyper-secreted using a Saccharomyces cerevisiae protein secretion system. An optimal secretion signal, a translation fusion partner (TFP) containing an N-terminal 98 amino acid domain from a mitochondrial inner membrane protein, UTH1, was employed to secrete approximately 50 U/mL of bioactive RaLsrA into culture media with 63% secretion efficiency by fed-batch fermentation. Although the purified RaLsrA was useful for enzymatic conversion of high-molecular-weight levan of approximately 3.75 × 106 Da, recombinant yeast secreting RaLsrA could produce levan more efficiently by microbial fermentation. In a 50-L scale fermenter, 76-g/L levan was directly converted from 191-g/L sucrose by recombinant yeast cells, attaining an 80% conversion yield and 3.17-g/L/h productivity. Thus, we developed a cost-effective and industrially applicable production system for food-grade levan.
Assuntos
Frutanos/biossíntese , Hexosiltransferases/metabolismo , Saccharomyces cerevisiae/metabolismo , Reatores Biológicos , Fermentação , Frutose/metabolismo , Hexosiltransferases/genética , Saccharomyces cerevisiae/genética , Sacarose/metabolismoRESUMO
The connection between the gut microbiome composition and human health has long been recognized, such that the host-microbiome interplay is at present the subject of the so-called "precision medicine". Non-digestible fructooligosaccharides (FOS) can modulate the microbial composition and therefore their consumption occupies a central place in a strategy seeking to reverse microbiome-linked diseases. We created a small library of Bacillus megaterium levansucrase variants with focus on the synthesis of levan- and inulin-type FOS. Modifications were introduced at positions R370, K373 and F419, which are either part of the oligosaccharide elongation pathway or are located in the vicinity of residues that modulate polymerization. These amino acids were exchanged by residues of different characteristics, some of them being extremely low- or non-represented in enzymes of the levansucrase family (Glycoside Hydrolase 68, GH68). F419 seemed to play a minor role in FOS binding. However, changes at R370 abated the levansucrase capacity to synthesize levan-type oligosaccharides, with some mutations turning the product specificity towards neo-FOS and the inulin-like sugar 1-kestose. Although variants retaining the native R370 produced efficiently levan-type tri-, tetra- and pentasaccharides, their capacity to elongate these FOS was hampered by including the mutation K373H or K373L. Mutant K373H, for instance, generated 37- and 5.6-fold higher yields of 6-kestose and 6-nystose, respectively, than the wild-type enzyme, while maintaining a similar catalytic activity. The effect of mutations on the levansucrase product specificity is discussed.
Assuntos
Proteínas de Bactérias/metabolismo , Frutanos/biossíntese , Hexosiltransferases/metabolismo , Oligossacarídeos/biossíntese , Sequência de Aminoácidos , Substituição de Aminoácidos , Bacillus megaterium/enzimologia , Proteínas de Bactérias/genética , Sítios de Ligação , Microbioma Gastrointestinal , Hexosiltransferases/genética , Inulina/biossíntese , Modelos Moleculares , Mutagênese Sítio-Dirigida , Polimerização , Conformação Proteica , Proteínas Recombinantes/metabolismo , Relação Estrutura-Atividade , Especificidade por SubstratoRESUMO
The probiotic features of strain GM newly isolated from Tunisian spontaneously fermented goat milk and identified as Bacillus tequilensis-GM were assessed. Strain GM showed high resistance to saliva (90.64%), gastric juice (88.55%), intestinal juice (72.83%) and resistance to bile salts (65.22%), was able to act against Listeria monocytogenes ATCC 15313, Escherichia coli ATCC 25922 and Enterococcus feacalis ATCC 25912, showed high surface hydrophobicity (77.3%) and was sensitive to most of the studied antibiotics. Strain GM did not exhibit any hemolytic activity whereas it was able to produce protease, amylase and ß-galactosidase. Moreover, results showed that strain GM produced high molecular weight ß-(2â¯ââ¯6)-levan with high ability to inhibit and to disrupt pathogenic biofilms and with high ability to reduce syneresis of sucrose-supplemented skimmed milk. B. tequilensis-GM can therefore be suitable to be used as starter culture in fermented dairy products, since it possesses desirable probiotic properties in addition to its ability to produce levan.
Assuntos
Bacillus/metabolismo , Fermentação , Frutanos/química , Frutanos/isolamento & purificação , Leite/microbiologia , Probióticos/metabolismo , Animais , Antibacterianos/biossíntese , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Ácidos e Sais Biliares/metabolismo , Biofilmes/efeitos dos fármacos , Frutanos/biossíntese , Frutanos/farmacologia , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/microbiologia , Cabras , Humanos , Interações Hidrofóbicas e HidrofílicasRESUMO
BACKGROUND: Jerusalem artichoke (Helianthus tuberosus L.) is a characteristic crop in the Qinghai-Tibet Plateau which has rapidly developed and gained socioeconomic importance in recent years. Fructans are abundant in tubers and represent the foundation for their formation, processing and utilization of yield; and are also widely used in new sugar-based materials, bioenergy processing, ecological management, and functional feed. To identify key genes in the metabolic pathway of fructans in Jerusalem artichoke, high-throughput sequencing was performed using Illumina Hi Seq™ 2500 equipment to construct a transcriptome library. RESULTS: Qinghai-Tibet Plateau Jerusalem artichoke "Qingyu No.1" was used as the material; roots, stems, leaves, flowers and tubers of Jerusalem artichoke in its flowering stage were mixed into a mosaic of the Jerusalem artichoke transcriptome library, obtaining 63,089 unigenes with an average length of 713.6 bp. Gene annotation through the Nr, Swiss Prot, GO, KOG and KEGG databases revealed 34.95 and 46.91% of these unigenes had similar sequences in the Nr and Swiss Prot databases. The GO classification showed the Jerusalem artichoke unigenes were divided into three ontologies, with a total of 49 functional groups encompassing biological processes, cellular components, and molecular functions. Among them, there were more unigenes involved in the functional groups for cellular processes, metabolic processes, and single-organism processes. 38,999 unigenes were annotated by KOG and divided into 25 categories according to their functions; the most common annotation being general function prediction. A total of 13,878 unigenes (22%) were annotated in the KEGG database, with the largest proportion corresponding to pathways related to carbohydrate metabolism. A total of 12 unigenes were involved in the synthesis and degradation of fructan. Cluster analysis revealed the candidate 12 unigene proteins were dispersed in the 5 major families of proteins involved in fructan synthesis and degradation. The synergistic effect of INV gene is necessary during fructose synthesis and degradation in Jerusalem artichoke tuber development. The sequencing data from the transcriptome of this species can provide a reliable data basis for the identification and assessment of the expression of the members of the INV gene family.A simple sequence repeat (SSR) loci search was performed on the transcriptome data of Jerusalem artichoke, identifying 6635 eligible SSR loci with a large proportion of dinucleotide and trinucleotide repeats, and the most different motifs were repeated 5 times and 6 times. Dinucleotide and trinucleotide repeat motifs were the most frequent, with AG/CT and ACC/GGT repeat motifs accounting for the highest proportion. CONCLUSIONS: In this study, a database search of the transcriptome of the Jerusalem artichoke from the Qinghai Tibet Plateau was conducted by high throughput sequencing technology to obtain important transcriptional and SSR loci information. This allowed characterization of the overall expression features of the Jerusalem artichoke transcriptome, identifying the key genes involved in metabolism in this species. In turn, this offers a foundation for further research on the regulatory mechanisms of fructan metabolism in Jerusalem artichoke.
Assuntos
Frutanos/biossíntese , Helianthus/genética , Transcriptoma , Metabolismo dos Carboidratos/genética , Helianthus/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Repetições de Microssatélites , Anotação de Sequência Molecular , TibetRESUMO
This study focused on kinetics of levan yield by Bacillus subtilis M, in a 150 L stirred tank bioreactor under controlled pH conditions. The optimized production medium was composed of (g/L): commercial sucrose 100.0, yeast extract 2.0, K2HPO4 3.0 and MgSO4â 7H2O 0.2; an increase in both carbohydrates consumption and cell growth depended on increasing the size of the stirred tank bioreactor from 16 L to 150 L. The highest levansucrase production (63.4 U/mL) and levan yield of 47 g/L was obtained after 24 h. Also, the specific levan yield (Yp/x) which reflects the cell productivity increased with the size increase of the stirred tank bioreactor and reached its maximum value of about 29.4 g/g cells. These results suggested that B. subtilis M could play an important role in levan yield on a large scale in the future. Chemical modifications of B. subtilis M crude levan (CL) into sulfated (SL), phosphorylated (PL), and carboxymethylated levans (CML) were done. The difference in CL structure and its derivatives was detected by FT-IR transmission spectrum. The cytotoxicity of CL and its derivatives were evaluated by HepGII, Mcf-7 and CaCo-2. In general most tested levans forms had no significant cytotoxicity effect. In fact, the carboxymethylated and phosphrylated forms had a lower anti-cancer effect than CL. On the other hand, SL had the highest cytotoxicity showing SL had a significant anti-cancer effect. The results of cytotoxicity and cell viability were statistically analyzed using three-way ANOVA.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Bacillus subtilis/metabolismo , Frutanos/química , Frutanos/farmacologia , Antineoplásicos/metabolismo , Reatores Biológicos , Biotecnologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Frutanos/biossíntese , HumanosRESUMO
Inulin, a natural fructan, cannot be hydrolyzed by digestive enzymes in the human body and plays a role as a dietary fiber and prebiotic. Due to its versatile physicochemical properties and physiological functions, inulin has been widely applied in food, pharmaceuticals, and many other fields. The microorganism-derived inulin-forming enzyme inulosucrase (ISase) (EC: 2.1.4.9) can biosynthesize higher-molecular-weight inulin than plants using sucrose as the sole substrate, and the enzyme also shows transfructosylation activity toward other saccharide acceptors. In this article, the properties, functions, and applications of inulin are overviewed. The biosynthesis of inulin by ISase is addressed, including ISase characteristics, structural features, molecular modifications and applications.