Search

Abstract: This study focused on the effects of five inorganic salts, NaCl, KCl, CaCl2, ZnCl2, and FeCl3, on the pretreatment of Miscanthus straw for sugar recovery and enzymatic digestibility. In the results, all of the salts reduced the hemicellulose content in the straw. Most notably, FeCl3 effected almost 100% xylan removal. Overall, the trivalent salts, which include FeCl3, had an especially significant influence on enzymatic digestibility of Miscanthus straw compared with the di- and mono-valent inorganic salts, which had relatively only minor effects. The salt impacts were in the following order: FeCl3 >ZnCl2 >CaCl2 >KCl>NaCl. Under the pretreatment condition of 0.5% FeCl3 at 200°C for 15min, 100% xylan removal and 71.6% enzymatic digestibility were obtained. Nevertheless, ZnCl2 get the better effect on total glucose content than that of FeCl3. [Copyright &y& Elsevier]

Abstract: This study investigated the effects of NH4Cl and MgCl2 on pretreatment and xylan hydrolysis of miscanthus straw for biofuels production. It was observed that increasing the pretreatment temperature decreased the remaining solid, increased the enzymatic digestibility, and increased the xylan removal. When 0.2–5.0% NH4Cl and MgCl2 were employed in pretreatments, increasing the inorganic salt concentration slightly diminished the remaining solid, though the enzymatic digestibility was enhanced. Under the higher-than-2% condition, no xylan remained in the solid residues after pretreatment. With pretreatment time, the remaining solid slightly decreased, but the enzymatic digestibility was increased. Moreover, xylan removal was linearly increased to 15min, after which it was completely hydrolyzed. Overall, these results indicated that pretreatment by 2% NH4Cl or MgCl2 at 185°C for 15min completely hydrolyzes the xylan of miscanthus straw. In scanning electron microscopy (SEM) images, the physical surface of the miscanthus straw showed an apparently damaged surface area and exposure of the internal structure after pretreatment with NH4Cl and MgCl2 by SEM. [Copyright &y& Elsevier]

Abstract: Parkinson''s disease is caused by a deficiency of the neurotransmitter dopamine. Since l-DOPA (l-3,4-dihydroxyphenylalanine) is a precursor of dopamine and can pass across the blood–brain barrier, it has been used as a treatment for Parkinson''s disease. Hundreds tons of l-DOPA are produced per year, and most of the current supply is produced by a chemical method of asymmetric synthesis. However, the chemical process for l-DOPA synthesis requires an expensive metal catalyst and shows low conversion rates and low enantioselectivity. In this study, we developed a novel technology for the production of l-DOPA, an electroenzymatic synthesis with a tyrosinase-immobilized cathode under the reduction potential of DOPAquinone, which is −530mV. Compared to other approaches for l-DOPA synthesis reported previously, this electroenzymatic system showed the highest conversion rate and a highly enhanced productivity of up to 95.9% and 47.27mgl−1 h−1, respectively. [Copyright &y& Elsevier]

Abstract: Sorbitan methacrylate was synthesized from sorbitan dehydrated from d-sorbitol using an immobilized lipase. To optimize the enzymatic synthesis of sorbitan methacrylate, response surface methodology was applied to determine the effects of five-level-four-factors and their reciprocal interactions on sorbitan methacrylate biosynthesis. A total of 30 individual experiments were performed, which were designed to study reaction temperature, reaction time, enzyme amount and substrate molar ratio. A statistical model predicted that the highest conversion yield of sorbitan methacrylate was 100%, at the following optimized reaction conditions: a reaction temperature of 43.06°C, a reaction time of 164.25min, an enzyme amount of 7.47%, and a substrate molar ratio of 3.98:1. Using these optimal factor values under experimental conditions in four independent replicates, the average conversion yield reached 98.7±1.2% and was well within the value predicted by the model. [Copyright &y& Elsevier]

H2S removal by immobilized cell bioreactor system was investigated using continuous glass column bioreactor with diameter of 90 mm and with a height of 1000 mm. Thiobacillus sp. IW was encapsulated inside the Ca-alginate bead in a continuous H2S removal bioreactor system and an optimum bioreactor performance was achieved at 1.5 l media volume, under the following conditions: operating temperature of 30 °C, pH 8, bead volume of 30%, and bead diameter of 2 mm. The most active cell-immobilized bead was made in a continuous bead maker at 3% Na-alginate, 3% CaCl2, and 2.0 g/l of cell concentration. We could remove H2S in the inlet stream completely up to 600 ppm of influent concentration. It could be confirmed by scanning electron microscope (SEM) that not only did the cells grow well inside the pores of the bead but they also grew out to the surface of the bead after the H2S removal reaction. It has so far successfully run the continuous H2S removal bioreactor for up to 240 h without pH control. [Copyright &y& Elsevier]

In this study, the hydrolysis of marine macro-algae Gracilaria verrucosa with a solid-acid catalyst was investigated. To optimize the hydrolysis, four reaction factors, including liquid-to-solid ratio, catalyst loading, reaction temperature, and reaction time, were investigated. In the results, the highest total reducing sugar (TRS) yield, 61 g/L (51.9%), was obtained under the following conditions: 1:7.5 solid-to-liquid ratio, 15% (w/v) catalyst loading, 140 °C reaction temperature, and 150 min reaction time. Under these conditions, 10.7 g/L of 5-HMF and 2.5 g/L of levulinic acid (LA) were generated. The application of solid-acid catalyst and marine macro-algae resources shows a very high potential for production of fermentable sugars. [ABSTRACT FROM AUTHOR]

l-DOPA (3,4-dihydroxyphenyl- l-alanine) has been widely used as a drug for Parkinson's disease caused by deficiency of the neurotransmitter dopamine. Since Monsanto developed the commercial process for l-DOPA synthesis for the first time, most of currently supplied l-DOPA has been produced by the asymmetric method, especially asymmetric hydrogenation. However, the asymmetric synthesis shows critical limitations such as a poor conversion rate and a low enantioselectivity. Accordingly, alternative biotechnological approaches have been researched for overcoming the shortcomings: microbial fermentation using microorganisms with tyrosinase, tyrosine phenol-lyase, or p-hydroxyphenylacetate 3-hydroxylase activity and enzymatic conversion by immobilized tyrosinase. Actually, Ajinomoto Co. Ltd commercialized Erwinia herbicola fermentation to produce l-DOPA from catechol. In addition, the electroenzymatic conversion system was recently introduced as a newly emerging scheme. In this review, we aim to not only overview the biotechnological l-DOPA production methods, but also to briefly compare and analyze their advantages and drawbacks. Furthermore, we suggest the future potential of biotechnological l-DOPA production as an industrial process. [ABSTRACT FROM AUTHOR]

We introduce a reactive extraction to detoxify hydrolysate before fermentation to biofuels. In the selection of diluents, n-octanol showed the highest removal yield of 5-hydroxymethylfurfural (5-HMF) and levulinic acid. The removal yields of inhibitors were normalized to 30-min reactions. In treatments with pure extractant or diluents, only 2 ∼ 4.1% of the formic acid was removed. Tri- n-octylamine (extractant) removed levulinic acid and acetic acid more efficiently, and furfural was removed more efficiently than formic acid or 5-HMF. n-Octanol (polar diluent) removed levulinic acid and acetic acid, furfural, and 5-HMF at 21.2, 33.7, and 65.7%, respectively. In contrast, kerosene (inert diluent) only removed the furfural by 27.6%. Based on these results, the optimum reactiveextraction system comprised tri- n-octylamine as the extractant, n-octanol as the polar diluent, and kerosene as the inert diluent. The optimal proportion of complex extractant was 20% trialkylamine, 70% n-octanol, and 10% kerosene. By detoxification, 63.9% of acetic acid and levulinic acid, 24.4% of 5-HMF, 63.9% of formic acid, and 64.0% of furfural could be removed. [ABSTRACT FROM AUTHOR]

In an effort to optimize the reaction conditions of biodiesel production from lard, response surface methodology was applied, and the effects of five-level-three-factors and their reciprocal interactions were assessed. A total of 20 individual experiments were conducted, and were designed to study reaction temperature, catalyst amount, and oil-to-methanol molar ratio. A statistical model predicted that the highest conversion yield of lard biodiesel would be 98.6%, at the following optimized reaction conditions: a reaction temperature of 65°C, a catalyst amount of 1.26%, and an oil-to-methanol molar ratio of 7.5:1, with a 20-min reaction time. Using these optimal factor values under experimental conditions in three independent replicates, an average content of 97.8±0.6% was achieved, and this value was well within the range predicted by the model. The quality of biodiesel produced from lard at the optimum reaction conditions satisfied the relevant quality standards, with the exception of cold filter plugging point. [Copyright &y& Elsevier]

This study investigates the phytosynthesis, characterization, and antibacterial efficacy of silver and gold nanoparticles (NPs) produced using the hot water extract of mixed woodchip powder. The woodchip extract (WCE) was successfully used as both a reducing and stabilizing agent for the phytosynthesis of both crystalline metal NPs. The effects of different physicochemical factors affecting the formation of the metal NPs including reaction pH, concentration of the precursor metal salts, amount of WCE, and external energy input were evaluated. The characterization of the metal NPs was performed by transmission electron microscopy, selected area electron diffraction (SAED), energy dispersive X-ray (EDX) spectroscopy, and X-ray diffraction (XRD) pattern analysis. In addition, the antibacterial efficacy of the phytosynthesized NPs was measured. The AgNPs showed clear antibacterial activity against four representative bacterial strains. However, the AuNPs did not exhibit bactericidal activity, probably due to their surface modifications and relatively large size. These results suggest that the phytosynthesis of the metal NPs using WCE is highly efficient, and its convenience makes it suitable for use in large-scale production. [ABSTRACT FROM AUTHOR]

Oil Palm Empty Fruit Bunch (OPEFB) is an abundant biomass resource in Indonesia, which contains 41.3 ~ 46.5% (w/w) of cellulose. This research examined the production of cellulase by the E. coli EgRK2 recombinant strain using an OPEFB substrate. The production of the enzyme was initially examined to identify optimum growth conditions, by observing the growth and activity of E. coli EgRK2 compared to its wild type. Our results showed that the optimum production time, pH and temperature of the recombinant growth and cellulase activity were achieved at 24 h, and at 7 and 40°C, respectively. Using these optimum conditions, the enzyme was produced, and experiments were carried out to examine the enzyme characteristics, produced from both strains, on hydrolysis of cellulose from OPEFB. Our results showed that the activity of the enzyme produced by the recombinant almost doubled compared to that of the wild type, although the optimum pH for both strains was pH 6. Higher activity was achieved by the recombinant compared to the wild type strain, and values were 1.905 and 1.366 U/mL, respectively. The optimum temperature for hydrolysis by cellulase occurred at 50°C for Bacillus sp. RK2, and 60°C for Bacillus sp. EgRK2. The Michaelis-Menten constant (Km) and maximum velocity (Vmax) for OPEFB degradation by E. coli EgRK2 were 0.26% and 1.750 μmol/mL/sec, which were significantly better values than those of the wild type. Control experiments for the degradation test using CMC also showed a better Vmax value for E. coli EgRK2 compared to the wild type, which is 2.543 and 1.605 μmol/mL/sec, respectively. [ABSTRACT FROM AUTHOR]

This work investigated the optimization of sugar and chemical formation from marine macro-green-alga Enteromorpha intestinalis by hydrothermal reaction and a statistical methodology. By this approach, the highest sugar and chemical yields were predicted as follows: glucose 10.42 %, xylose-mannose-galactose (XMG) 18.08 %, total reducing sugar (TRS) 28.61 % (reaction temperature 156 °C, catalyst amount 1.3 %, reaction time 11.4 min), levulinic acid 4.00 % (175.0 °C, 3.7 %, 35 min), 5-hydroxymethylfurfural 1.71 % (186.0 °C, 1.1 %, 37.9 min), and furfural 2.03 % (183.1 °C, 2.2 %, 10.7 min). In terms of the combined severity factor (CSF), the glucose, XMG, and TRS production decreased linearly with increasing CSF and to a high correlation. This application of a marine green-alga shows a high potential for production of fermentable sugars and chemicals suitable for biorefinement processes. [ABSTRACT FROM AUTHOR]

Dopamine, the most important neurotransmitter in the human brain, controls various functions. Dopamine deficiency causes fatal neurological disorders such as Parkinson's disease. Even though various types of electrochemical sensors have been studied to measure dopamine levels, they often have poor selectivity for dopamine due to co-existence of interfering substances (e.g. ascorbic acid). Herein, we aimed to develop a highly sensitive dopamine detection method in the co-existence of ascorbic acid, a major interfering substance in real sample by designing an electrochemically pretreated and activated carbon/tyrosinase/Nafion®-modified GCE as an amperometric dopamine biosensor. To maximize the biosensor performance, pH, volume of Nafion®, and scan rate were optimized. This electrochemically pretreated and activated carbon/tyrosinase/ Nafion®-modified GCE could detect as low as 50 μM of dopamine with a wide linear range (50 ~ 1,000 μM) within a few seconds. In addition, it had a sensitivity of 103mAM/cm, which was higher than all previously reported tyrosinasebased dopamine biosensors. In addition, interference effect caused by 4 mM of ascorbic acid was negligible in the co-existence of 1 mM of dopamine. Consequently, this electrochemically pretreated and activated carbon/tyrosinase/ Nafion®-modified GCE might be applicable as amperometric biosensor for selective detection of dopamine in real samples with interfering substances. [ABSTRACT FROM AUTHOR]

Abstract: Deinococcus radiodurans is a bacterium best known for its extreme resistance to high levels of ionizing radiation. Gene expression profiles of D. radiodurans exposed to 0.3 M NaCl revealed that at least 389 genes were induced and 415 were repressed by twofold or more. A general down-regulation of the central metabolic pathways and a strong decrease of nrd gene expression, which encodes proteins necessary for DNA synthesis, likely reflect the growth retardation induced by NaCl stress. The expression of rsbRSTX, which encodes sigma B (σB) activity regulators, was also reduced by NaCl stress even though D. radiodurans does not have σB. The mutation of rsbX (drB0027) decreased the tolerance of D. radiodurans to NaCl, suggesting the possible role of the Rsb module in NaCl response. On the other hand, NaCl stress activated genes associated with osmoprotectant accumulation: the pstSCAB operon, which encodes a high affinity phosphate transporter, and DRA0135 and DR1438, which are components of transporters of glycine betaine and trehalose. Survival analysis of mutant strains lacking DR0392 (membrane-binding protein) and DR1115 (S-layer protein), whose expressions were highly activated by NaCl, showed a reduction in NaCl tolerance. In addition, the Δdr0392 strain showed sensitivity to γ-irradiation compared to the wild type. These results suggest that DR0392 plays a role in the resistance of D. radiodurans to NaCl and γ-irradiation. [Copyright &y& Elsevier]

Abstract: Recently, many research works have reported on improvements to the saccharification process that increase bioethanol production from cellulosic materials. Gamma irradiation has been studied as an effective method for the depolymerization of complex polysaccharides. In this study, the effect of gamma irradiation on saccharification of Undaria biomass for bioethanol production was investigated. The Undaria biomass was irradiated at doses of 0, 10, 50, 100, 200 and 500kGy and then hydrolyzed using sulfuric acid. The effects of gamma irradiation were measured through microscopic analysis to determine morphological changes and concentration of the reducing sugar of hydrolysates. Microscopic images show that gamma irradiation causes structure breakage of the Undaria cell wall. The concentration of reducing sugar of hydrolysates significantly increased as a result of gamma irradiation, with or without acid hydrolysis. These results indicate that the combined method of gamma irradiation with acid hydrolysis can significantly improve the saccharification process for bioethanol production from marine algae materials. [Copyright &y& Elsevier]

The effect of light on melatonin biosynthesis was examined in detached rice ( Oryza sativa cv. Asahi) leaves during the senescence process. The detached leaves were exposed to senescence treatment either in constant darkness or in constant light, and subjected to HPLC analysis for melatonin and its precursors. Higher melatonin levels were detected in rice leaves under constant light while very low levels were observed in constant darkness. Levels of the melatonin intermediates, tryptamine, serotonin, and N-acetylserotonin significantly decreased in the dark compared to those in the light. Furthermore, relative mRNA levels of melatonin biosynthetic genes and their corresponding proteins decreased accordingly in constant darkness. The most striking difference between constant light and dark was observed in levels of the protein tryptamine 5-hydroxylase. These results suggest that melatonin biosynthesis during senescence is dependent on light signals in rice leaves, contrary to the response found in animals. [ABSTRACT FROM AUTHOR]

Abstract: Previously, using γ-irradiation treatment, we isolated a mutant strain of Klebsiella pneumoniae (named GEM167) that showed high-level ethanol production from glycerol. In the present study, in an effort to enhance ethanol production, we used a deletion of the lactate dehydrogenase gene to engineer a mutant strain incapable of lactate synthesis. In the ΔldhA mutant of GEM167, the production of ethanol was significantly increased from 21.5g/l to 28.9g/l and from 0.93g/(lh) to 1.2g/(lh). Introduction of the Zymomonas mobilis pdc and adhII genes encoding pyruvate decarboxylase and aldehyde dehydrogenase, respectively, further improved the ethanol production level from glycerol to 31.0g/l; this is the highest level reported to date. [Copyright &y& Elsevier]

Abstract: With the aim of isolating a biocatalyst able to catalyze biodiesel production from microbial source, Ralstonia sp. CS274 was isolated and a lipase from the strain (RL74) was purified. Molecular weight of RL74 was estimated to be 28,000Da by SDS–PAGE. The activity was highest at 50–55°C and pH 8.0–9.5 and was stable at pH 7.0–12.0 and up to 45°C. It was resistant to oxidizing and reducing agents and the activity was enhanced by detergents. RL74 was 1,3 specific and K m and V max for p-nitrophenyl palmitate were 2.73±0.6mM and 101.4±1.9mM/minmg, respectively. N-terminal amino acid sequence showed partial homology with that of Penicillium lipases. RL74 produced biodiesel more efficiently in palm oil than in soybean oil; and the production was highest at pH 8.0, at 5% methanol and at 20% water content. [Copyright &y& Elsevier]

Abstract: A mutant strain of Klebsiella pneumoniae, termed GEM167, was obtained by γ irradiation, in which glycerol metabolism was dramatically affected on exposure to γ rays. Levels of metabolites of the glycerol reductive pathway, 1,3-propanediol (1,3-PD) and 3-hydroxypropionic acid (3-HP), were decreased in the GEM167 strain compared to a control strain, whereas the levels of metabolites derived from the oxidative pathway, 2,3-butanediol (2,3-BD), ethanol, lactate, and succinate, were increased. Notably, ethanol production from glycerol was greatly enhanced upon fermentation by the mutant strain, to a maximum production level of 21.5g/l, with a productivity of 0.93g/l/h. Ethanol production level was further improved to 25.0g/l upon overexpression of Zymomonas mobilis pdc and adhII genes encoding pyruvate decarboxylase (Pdc) and aldehyde dehydrogenase (Adh), respectively in the mutant strain GEM167. [ABSTRACT FROM AUTHOR]

Abstract: In this study, pilot-scale experiments for the removal of nitrogen from sewage obtained from a county Y sewer system were performed using modified A2O processes. Using this approach, the total amount of nitrogen discharged during denitrification of the influent was average 38.6mg/L and a level of average 10.8mg/L was maintained throughout the denitrification process, which resulted in an average removal efficiency that was greater than 72%. The nitrogen components in the effluent water consisted of 22% ammonia nitrogen, 6% nitrite nitrogen and 72% nitrate nitrogen, reaching a nitrification efficiency of 94%. In conclusion, since these advanced treatment methods, which involve modified A2O processes, were successfully employed to remove nitrogen from sewage discharge, they hold promise for wide spread use by treatment plants. [Copyright &y& Elsevier]

Abstract: “Biomaterials” is a generic term which refers to a variety of medical material which is designed to be in direct contact with living tissue. Clearly, biomaterials must be carefully and microscopically fabricated for optimal acceptance within the living organism, in both functional and structural senses. In this study, the enzymatic synthesis of sorbitan methacrylate from 1,4-sorbitan via the manipulation of an immobilized biocatalyst (Novozym 435) and acryl donors (methacrylic acid and vinyl methacrylate) was evaluated. The conversion yield of sorbitan methacrylate was found to be 80.4% under the following experimental conditions: 1:3 molar ratio of 1,4-sorbitan and vinyl methacrylate, reaction temperature of 50°C, initial sorbitan concentration of 50g/L, and 3% (w/v) Novozym 435. [Copyright &y& Elsevier]