1,721,048 research outputs found
Antioxidant Compounds for the Inhibition of Enzymatic Browning by Polyphenol Oxidases in the Fruiting Body Extract of the Edible Mushroom Hericium erinaceus
No full textMushrooms are attractive resources for novel enzymes and bioactive compounds. Nevertheless, mushrooms spontaneously form brown pigments during food processing as well as extraction procedures for functional compounds. In this study, the dark browning pigment in the extract derived from the edible mushroom Hericium erinaceus was determined to be caused by the oxidation of endogenous polyphenol compounds by the polyphenol oxidase (PPO) enzyme family. These oxidized pigment compounds were measured quantitatively using a fluorospectrophotometer and, through chelation deactivation and heat inactivation, were confirmed to be enzymatic browning products of reactions by a metalloprotein tyrosinase in the PPO family. Furthermore, a transcript analysis of the identified putative PPO-coding genes in the different growth phases showed that tyrosinase and laccase isoenzymes were highly expressed in the mushroom fruiting body, and these could be potential PPOs involved in the enzymatic browning reaction. A metabolite profiling analysis of two different growth phases also revealed a number of potential enzymatic browning substances that were grouped into amino acids and their derivatives, phenolic compounds, and purine and pyrimidine nucleobases. In addition, these analyses also demonstrated that the mushroom contained a relatively high amount of natural antioxidant compounds that can effectively decrease the browning reaction via PPO-inhibitory mechanisms that inhibit tyrosinase and scavenge free radicals in the fruiting body. Altogether, these results contribute to an understanding of the metabolites and PPO enzymes responsible for the enzymatic browning reaction of H. erinaceus
A novel core 1 O-linked glycan-specific binding lectin from the fruiting body of Hericium erinaceus
No full textMucin-type O-glycans are involved in biological functions on the cell surface as well as the glycoproteins and can also be used as specific carbohydrate biomarkers of many diseases. In this study, I purified a novel core 1 O-linked glycan specific lectin, Hericium erinaceus lecin (HeL), from the fruiting body of the mushroom Hericium erinaceus, which is known as the natural source for a sialic acid-binding lectin. Upon optimization of the purification conditions, a sequence of ion exchange, affinity, ion exchange, and size-exclusion chromatography resulted in the highest yield and best quality of lectin without protease activity. The resulting purified HeL is an apparent hexameric protein with a subunit molecular weight of 15 kDa, and a pI of 4.3. In hemagglutination inhibition assay, the purified lectin was only inhibited by glycoproteins containing mucin-type O-glycans and reacted weakly with Galβ(1,3)GalNAc. Glycan array analyses showed that HeL specifically interacts with core 1 O-linked glycans as well as extended O-glycan structures containing sialylation or fucosylation. The glycan binding specificity of HeL is comparable to that of peanut agglutinin for detection of a broader range of extended core 1 O-glycan structures. Taken together, these results provide an efficient and optimized procedure for the purification of HeL from the fruiting body of the mushroom Hericium erinaceus. Moreover, HeL represents a powerful tool for analyzing core 1 and extended core 1 O- glycan structures in diagnosis assays
Ricin B-like lectin orthologues from two mushrooms, Hericium erinaceus and Stereum hirsutum, enable recognition of highly fucosylated N-glycans
No full textThe mushroom Hericium erinaceus contains isolectins, including the ricin B-like lectin HEL1 and the core 1 O-glycan-binding lectin HEL2. Recombinant HEL2 reportedly binds O-linked glycans, but recombinant HEL1 (rHEL1) has not been characterized. HEL1 and Stereum hirsutum lectin (SHL1) orthologues, which contain the typical (QxW)3 ricin-B like motif, were evaluated. Interestingly, under non-denaturing conditions, recombinant SHL1 (rSHL1) existed as a trimer and exhibited agglutination activity, whereas rHEL1 existed as a monomer with no agglutination activity. The hemagglutination activity of rSHL1 was inhibited by N-linked glycoprotein transferrin. A glycan-array analysis revealed that the two recombinant lectins had different binding intensities toward fucosylated N-glycans harboring fucose-α(1,2) galactose or fucose-α(1,4) N-acetylglucosamine. Isothermal calorimetry showed that compared with rHEL1, rSHL1 interacted more strongly with transferrin, a fucosylated glycoprotein, than with other fucosylated disaccharide glycoconjugates. Finally, rSHL1 and rHEL1 were comparable in their ability to detect highly fucosylated N-glycans within glycoproteins on the surface of SW1116 human colorectal carcinoma cells. Therefore, these ricin B-like lectins might enable detection of highly fucosylated glycoepitopes on cancer cells for diagnostic applications.
Production of cellulase enzymes during the solid-state fermentation of empty palm fruit bunch fiber
No full textPenicillium verruculosum COKE4E is a fungal strain isolated from bituminous coal. The microorganism cultivated in a minimal medium supplemented with Avicel, carboxymethylcellulose, and oat spelt xylan produced cellulase enzymes as exhibiting carboxymethylcellulase (CMCase), Avicelase, xylanase, and cellobiosidase activities. In this study, the productivity of the extracellular enzymes in the strain was evaluated by using empty palm fruit bunch fiber (EPFBF), a lignocellulosic biomass, as a substrate for solid-state bioconversion. The highest cellulase activities were observed after 6 days of fermentation at pH 6.0 and 30 °C. The enzymes were secreted as cellulosomes for the degradation of EPFBF as a sole carbon source. Focused ion beam analysis showed that P. verruculosum COKE4E produced cellulolytic enzymes that were able to effectively biodegrade EPFBF during solid-state fermentation. In this process, 6.5 U of CMCase, 6.8 U of Avicelase, and 8.8 U of xylanase per gram of dry solid EPFBF were produced. These results demonstrate that EPFBF may be a potential raw material in solid-state fermentation for the production of cellulase enzymes to be used for biofuel production.open
Bioethanol production using the sequential acid/alkali-pretreated empty palm fruit bunch fiber
No full textEmpty palm fruit bunch (EPFB) contains a rigid and ordered fiber structure within a relatively high level of hemicellulose and lignin. To enhance poorly enzymatic digestibility and fermentability, in this a sequential acid/alkali pretreatment strategy was applied to increase the fermentable sugar in EPFB fiber. Cellulose content in the biomass was effectively increased by using dilute sulfuric acid treatment to eliminate hemicellulose followed by highly concentrated sodium hydroxide treatment for delignification. The pretreated biomass consisted of 85.2 ± 1.9% cellulose, 1.8 ± 0.5% hemicellulose, and 9.2 ± 0.3% lignin. Under optimal conditions for enzymatic saccharification, 10% (w/v) of pretreated EPFB fiber was hydrolyzed completely and converted to 70.8 ± 0.8 g/L glucose and 1.8 ± 0.1 g/L xylose with a 83.9% yield efficiency. Simultaneous saccharification and fermentation of the pretreated biomass by Saccharomyces cerevisiae W303-1A produced 37.8 g/L ethanol in 1.5 L fermented medium containing 10% (w/v) pretreated EPFB fiber after 60 h. The ethanol productivity was 0.378 g ethanol/g dry EPFB fiber and 0.45 g ethanol/g glucose after fermentation, with a low concentration of xylose and organic acid metabolites. Also, 88% of fermentable sugar was used by the yeast for ethanol fermentation. These results indicate that sequential acid/alkali pretreatment increased enzymatic digestibility and ethanol productivity.open
Evaluation of whole Jerusalem artichoke (Helianthus tuberosus L.) for consolidated bioprocessing ethanol production
No full textFor consolidated bioprocessing (CBP), components of Jerusalem artichoke (Helianthus tuberosus L.) tubers and stalks as a potential bioenergy crop were analyzed as carbon and nutrient sources, respectively. The effectiveness of chemical pretreatment with dilute acid or alkali was evaluated to develop a CBP method. Cellulose content, delignification, and enzymatic hydrolysis efficiency of the pretreated stalks were increased more effectively by NaOH treatment than dilute H2SO4 treatment. However, weight loss was greater during alkali pretreatment. Additionally, large volumes of water were required to wash the alkali-treated biomass. Therefore, CBP using the dilute acid-pretreated stalk and the ground tuber of Kluyveromyces marxianus were investigated. Fermentation of both pretreated stalks and tubers by K.marxianus with no nutrient supplementation proceeded acceptably. At 10% (w/v) stalk and 8% (w/v) tuber loading, K.marxianus produced 45.3g/L ethanol after 30h. The ethanol yield was 0.252g ethanol per g dry biomass, or 0.32g ethanol per g fermentable sugars, with a fermentable sugar conversion rate of 60%. These results suggest a cost-effective CBP strategy for bioethanol production from the whole Jerusalem artichoke plant.open
Evaluation of the wastewater generated during alkaline pretreatment of biomass for feasibility of recycling and reusing
No full textWe evaluated the wastewater generated in the alkali pretreatment process of Miscanthus sacchariflorus with sodium hydroxide for the feasibility of recycling and reusing. After thermal alkali pretreatment of the biomass, the separated alkaline solution and the biomass wash water were filtrated using several different types of membranes to recover sodium hydroxide, as well as to eliminate lignin-hemicellulose fractions from the wastewater. Ion concentration, total organic carbon, and acid-hydrolyzed carbohydrate contents were analyzed to evaluate the quality of the alkaline wastewater. The data indicated that a poly(ether)sulfone-based ultrafiltration (UF) membrane filter with a low molecular weight cut-off was able to recover > 98% sodium ions and to remove > 60% of solubilized organic carbon fractions from the alkaline wastewater. These results indicated that filtration using UF membrane could be an alternative strategy to reuse wastewater and to recover the alkali catalyst in the alkali pretreatment process.
Ethanol production using whole plant biomass of Jerusalem artichoke by Kluyveromyces marxianus CBS1555
No full textJerusalem artichoke is a low-requirement sugar crop containing cellulose and hemicellulose in the stalk and a high content of inulin in the tuber. However, the lignocellulosic component in Jerusalem artichoke stalk reduces the fermentability of the whole plant for efficient bioethanol production. In this study, Jerusalem artichoke stalk was pretreated sequentially with dilute acid and alkali, and then hydrolyzed enzymatically. During enzymatic hydrolysis, approximately 88 % of the glucan and xylan were converted to glucose and xylose, respectively. Batch and fed-batch simultaneous saccharification and fermentation of both pretreated stalk and tuber by Kluyveromyces marxianus CBS1555 were effectively performed, yielding 29.1 and 70.2 g/L ethanol, respectively. In fed-batch fermentation, ethanol productivity was 0.255 g ethanol per gram of dry Jerusalem artichoke biomass, or 0.361 g ethanol per gram of glucose, with a 0.924 g/L/h ethanol productivity. These results show that combining the tuber and the stalk hydrolysate is a useful strategy for whole biomass utilization in effective bioethanol fermentation from Jerusalem artichoke.open
Sequential acid-/alkali-pretreatment of empty palm fruit bunch fiber
No full textPretreatment processes are key technologies for generating fermentable sugars based on lignocellulosic biomass. In this study, we developed a novel method for empty palm fruit bunch fiber (EPFBF) using sequential pretreatment with dilute acid and then alkali. Dilute sulfuric acid was used in the first step, which removed 90% of the hemicellulose and 32% of the lignin, but left most of the cellulose under the optimum pretreatment condition. Sodium hydroxide was then applied in the second step, which extracted lignin effectively with a 70% delignification yield, partially disrupting the ordered fibrils of the EPFBF and thus enhancing the enzyme digestibility of the cellulose. The sequentially pretreated biomass consisted of 82% cellulose, less than 1% hemicellulose, and 30% lignin content afterward. The pretreated biomasses morphologically revealed rough, porous, and irregularly ordered surfaces for enhancing enzyme digestibility. These results indicate that the sequentially acid/alkali-pretreated EPFBF could be broadly useful as a novel biomass.open
- …
