NC State
  • Researchpp 4012-4021Asgher, M., Irshad, M., and Iqbal, H. M. N. (2012). "Purification and characterization of LiP produced by Schyzophyllum commune IBL-06 using banana stalk in solid state cultures," BioRes. 7(3), 4012-4021.AbstractArticlePDF

    Lignin peroxidase was produced from Schyzophyllum commune IBL-06 through solid state fermentation of an abundantly available agro-industrial waste, banana stalk, under pre-optimized conditions. LiP was fractionated by 65% saturation with NH4SO4 and dialysis to 1.5-fold purification. The enzyme was further purified by Sephadex G-100 gel filtration chromatography to 2.34 fold with specific activity of 468 U/mg. A single band of 80 kDa was obtained on native gel while on sodium dodecyl sulphate polyacrilamide gel electrophoresis (SDS-PAGE), and two bands having molecular weight of 33 & 47 kDa were obtained, suggesting that LiP was a two polypeptide oligomeric protein. The present LiP from S. commune IBL-06 was optimally active at pH 5 and 35oC. The stability assay showed that LiP retained activity in an acidic pH range of 4 to 6 and a temperature of 25 to 45°C after 24 h of incubation. Lignin peroxidase oxidized the vertry alcohol and showed kinetic constants KM and Vmax values of 0.46 mM and 388 mM/min, respectively. All organic and inorganic compounds inhibited S. commune LiP, but EDTA, β-Marcaptoethanol, and Pb(NO3)2 were the most inhibitory.

  • Researchpp 4022-4030Wu, J., Wang, H., Yang, X., Wan, J., Liu, P., Xu, Q., Tang, Y., and Zhang, X. (2012). "Dietary fiber production from sweet potato residue by solid state fermentation using the edible and medicinal fungus Schizophyllum commune," BioRes. 7(3), 4022-4030.AbstractArticlePDF

    Dietary fiber (DF) has attracted increasing interest from nutritionists. The yield of DF by traditional extraction methods, however, is very low. This paper aims to increase the yield of DF by solid state fermentation using the edible and medicinal fungus Schizophyllum commune. Sweet potato residue (SPR) was selected as raw material for producing DF. Results showed that SPR was a good feedstock for DF production by solid state fermentation. Optimized conditions of solid state fermentation of SPR for DF were obtained as follows: material particle size = 1.8 mm to 2.5 mm, water moisture at 65%, natural lighting radiation, and temperature at 27 °C. Under the optimal conditions, the yield and DF content in fermented SPR were more than 80% and 70%, respectively. The increased DF yield was mainly attributable to increased cellulose and hemicelluloses conversion. Swelling capacity, water-holding capacity, oil-holding capacity, and glucose absorption capacity of the fermented SPR were also determined, and the data indicated that the fermented SPR could be considered as a new good DF. Therefore, this work showed us a novel bioconversion method to produce high-quality DF, and the yield of DF increased 4-fold compared with traditional extraction methods.

  • Researchpp 4031-4045Zhang, W., Liu, C., Wang, G., Ma, Y., Zhang, K., Zou, S., and Zhang, M. (2012). "Comparison of the expression in Saccharomyces cerevisiae of endoglucanase II from Trichoderma reesei and endoglucanase I from Aspergillus aculeatus," BioRes. 7(3), 4031-4045.AbstractArticlePDF

    Two distinct expression cassettes were synthesized by overlapping PCR for expressing the endoglucanase I gene (egl1) from Aspergillus aculeatus and the endoglucanase II gene (egl2) from Trichoderma reesei in a Saccharomyces cerevisiae host. One contained the anchored sequence from the S. cerevisiae cwp2 gene, while the other did not. The low and high copy number plasmids YCplac33 and YEplac195 were used. The enzymatic activities and viscosity changes in the YP-CMC medium varied between the eight recombinant yeast strains produced, and the greatest values were obtained with the YE-TrEII’ strain, which had an activity of 347.7 U/g dry cell weight (DCW) and viscosity at 12 h of 4.7% of the initial control value, respectively; YE-TrEII’ was YEplac195-based and contained T. reesei egl2 and no Cwp2 sequence. Strains YC-AaEI and YC-TrEII showed the lowest enzyme activitiy (80.5 and 30.4 U/g DCW, respectively) and viscosity changes at 12 h (20.5 and 26.2% of the initial control viscosity, respectively), which were YCplac33-based and contained the Cwp2 sequence. The results showed that gene copy number was the most significant factor to influence the expression of endoglucanases in S. cerevisiae, and the existence of Cwp2 sequence led to decreased enzymatic level and viscosity-reducing performance, while it was shown not to realize efficient surface display of these two endoglucanases.

  • Researchpp 4046-4055Requejo, A., Rodríguez, A., Colodette, J. L., Gomide, J. L., and Jiménez, L. (2012). "Optimization of ECF bleaching and refining of kraft pulping from olive tree pruning," BioRes. 7(3), 4046-4055.AbstractArticlePDF

    The aim of the present work was to find an optimum kraft pulping process for olive tree pruning (OTP) in order to produce a bleachable grade pulp of Kappa number about 17. The kraft pulp produced under optimized conditions showed a viscosity of 31.5 mPa.s and good physical, mechanical, and optical properties, which are acceptable for paper grade production. The strength and optical properties were measured on pulps unrefined and refined in a PFI mill with up to 2000 revolutions before and after bleaching. The OTP pulp was bleached to 90% ISO brightness (kappa < 1); however the process demanded a long sequence of stages, OD(EP)D(EP)D, and a higher than usual total chemical dosage (24.78 kg/odt pulp). Overall, OTP is suggested as an interesting raw material for cellulosic pulp production because its properties are comparable to those of other agricultural residues currently used in the paper industry.

  • Researchpp 4056-4066Liao, W., Lai, Y.-C., Huang, C.-L., and Lien, C.-Y. (2012). "Characterization of physicochemical properties of Miscanthus floridulus stems and study of their oil absorption ability using gold nanoparticles," BioRes. 7(3), 4056-4066.AbstractArticlePDF

    Miscanthus floridulus, which originated from a high elevation mountain area in Taiwan, is a newly cultivated species of Miscanthus. Instead of Miscanthus × giganteus, M. floridulus can be used as an alternative fuel for energy production as well. Except for leaves, stems of M. floridulus count for a major portion of the biomass. In this study, the lignin and cellulose contents of M. floridulus stems were determined to be 22.33 ± 2.21% and 43.13 ± 2.79%, respectively. In addition, a new application of M. floridulus stems was proposed. Oil absorption ability represented by the amount of soybean and motor oils absorbed by one gram of pulverized M. floridulus stems was estimated to be 2.25 ± 0.25 and 2.33 ± 0.18 g, respectively. Gold nanoparticles were used to investigate the absorption ability of M. floridulus stems. The absorption of gold nanoparticles by M. floridulus stems was visualized using SEM and TEM. In addition, the IR spectrum of M. floridulus stems was recorded for comparison with other studies.

  • Researchpp 4067-4084Urruzola, I., Andrés, M. A., Serrano, L., and Labidi, J. (2012). "Adsorption of toluene onto bleached eucalyptus pulp treated with ultrasound," BioRes. 7(3), 4067-4084.AbstractArticlePDF

    Bleached kraft semichemical eucalyptus pulp was used as raw material to adsorb an organic compound, toluene, from aqueous solution. The pulp was sonicated with different powers and different times to obtain smaller cellulose fibers. The adsorption capacity for toluene of sonicated fibers and bleached eucalyptus pulp was measured by ultraviolet spectroscopy. The absorption capacity for toluene was increased considerably when cellulose nanofibres were obtained. The adsorption capacity of bleached eucalyptus pulp was 36 μmol/g, while sonicated fibres at 30 W and 20 hours increased the adsorption by 47% and at 50 W and 20 h increased it by 67% compared with untreated fibres. Visual examination and optical microscopy were used to observe the reduction of fibers width and the dispersion increase. Contact angle measurements were used to analyze the variation of hydrophilic character of cellulose. Fourier transform infrared spectroscopy was used to study variations introduced by the ultrasound treatments on the chemical structure of the samples. The adsorption capacity studies showed that the treatment with ultrasound improved the retention capacity of the fibres, increasing considerably the adsorption capacity when the fiber width approached the nanoscale.

  • Researchpp 4085-4097Shi, Y., Yokoyama, T., Akiyama, T., Yashiro, M., and Matsumoto, Y. (2012). "Degradation kinetics of monosaccharides in hydrochloric, sulfuric, and sulfurous acid," BioRes. 7(3), 4085-4097.AbstractArticlePDF

    The degradation kinetics of monosaccharides during sulfurous acid treatment was compared to hydrochloric acid and to sulfuric acid treatments. Reaction conditions corresponded to the range found in previous research to allow for the production of hemicelluloses-derived monosaccharides through hydrolysis of wood. Degradation behavior of monosaccharides during treatment with each acid was expressed by a second-order reaction rate constant with respect to substrate and acid concentrations, and the activation energy and frequency factor were calculated using the Arrhenius equation. Results demonstrated that the second-order reaction rate of a monosaccharide was dependent on the type of acid, indicating that monosaccharides degrade at different rates under different acids, even when the molar concentration of the acid is the same. The degradation of monosaccharides in sulfurous acid was much slower than that in hydrochloric acid and in sulfuric acid. A comparison of two sequential treatments with sulfuric acid, with and without the bisulfite ion, showed that sulfurous acid has a protective effect on the degradation of monosaccharides.

  • Researchpp 4098-4108Ncube, E., Chungu, D., Kamdem, D. P., and Musawa, K. (2012). "Use of a short span field test to evaluate termite resistance of Eucalyptus grandis and Bobgunnia madagascariensis in a tropical environment," BioRes. 7(3), 4098-4108.AbstractArticlePDF

    Despite being treated with preservatives, the service life of transmission poles and fence posts in the Zambian Copperbelt province is close to fifteen years. However, the service life is only two years for untreated timber, mainly due to termite damage. This short service life is exerting more pressure on an already over-burdened timber resource base. This study used an accelerated field test investigation to facilitate initial assessment of several lesser known indigenous timbers for their termite resistance properties. To determine the service life and natural durability of Eucalyptus grandis and Bobgunnia madagascariensis to termite attack, samples of each wood species were field exposed to an aggressive species of subterranean termites for 32 days. Morphological and genetic analyses confirmed that the aggressive species of termites in this study was Coptotermes formosanus, commonly referred to as Formosan subterranean termites. Results indicated that E. grandis can be labeled as susceptible (S) following the standard natural durability rating procedure on the basis of service life projected from short term field exposure weight loss determination. Using short duration exposure weight loss and visual designation, similar to the Gulfport scale, B. madagascariensis was designated as very durable (D). These results showed that natural durability of timber against termites can be estimated after a short duration field exposure to Formosan subterranean termites. This method offers a fast field test for screening of promising lesser known tropical timbers.

  • Researchpp 4109-4121Cao, Y., Chan, F., Chui, Y.-H., Xiao, H. (2012). "Characterization of flax fibres modified by alkaline, enzyme, and steam-heat treatments," BioRes. 7(3), 4109-4121.AbstractArticlePDF

    Flax fibres are being considered as an environmentally friendly alternative to synthetic fibres in fibre-reinforced polymer composites due to their low density, biodegradability, and high mechanical strength. Previous work has found that the surface properties of natural fibres can be modified by chemical treatment and other treatment methods. This study focused on the effect of different treatments using alkaline, enzyme, and steam-heat, respectively, on some surface characteristics of flax fibre, e.g. physical, chemical, and thermal stability. Using scanning electron microscopy (SEM), treated fibres were observed to have smoother surfaces than untreated fibres. Chemical composition of fibres was found to be modified after treatment as characterized by Fourier transform infrared spectroscopy (FTIR). The crystallinity index and thermal stability of flax fibres were increased after certain treatments as determined by X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. The wettability of treated fibre by water was improved compared to the untreated sample.

  • Researchpp 4122-4131Yen, P.-L., Wu, C.-L., Chang, S.-T., Huang, S.-L., and Chang, H.-T. (2012). "Antioxidative lignans from phytochemical extract of Calocedrus formosana Florin," BioRes. 7(3), 4122-4131.AbstractArticlePDF

    Antiradical and antioxidant activities of ethanolic extract and its fractions from Calocedrus formosana Florin heartwood were investigated, and active compounds were identified by spectral analyses. Among extract and three fractions, the ethyl acetate soluble fraction had a high total phenolic content and exhibited the desirable reducing power, antiradical activity, and antioxidant activity. The compounds haplomyrfolin, O-ethyl-α-conidendral, matairesinol, 7,8-dehydro-4-O-methyl-thujaplicatin, and 5-methoxy-isosalicifoline were isolated from antioxidative activity guided fractionation of the ethyl acetate soluble fraction. Haplomyrfolin and O-ethyl-α-conidendral were for the first time isolated and identified from C. formosana. Matairesinol and 5-methoxy-isosalicifoline exhibited superior DPPH radical scavenging ability and antioxidant activity, as evaluated by TEAC assay. Results obtained in the present study revealed that ethyl acetate soluble fraction from C. formosana heartwood extract and its active compounds, matairesinol and 5-methoxy-isosalicifoline, exhibit antioxidant potential as natural nutraceuticals.