Volume 15 Issue 2

Fungi were isolated using a rose bengal chloramphenicol agar as the culture medium. Congo red staining was used on sodium carboxymethyl cellulose medium to screen fungal strains that have potential to produce cellulolytic enzymes according to the cellulolytic index (CI). The ability of these isolates to break down holocellulose in three forest litter substrates (broad-leafed: Juglans mandshurica; coniferous: Larix gmelinii; broadleaf-conifer mixed: J. mandshurica and L. gmelinii) was tested over 80 days of incubation. The holocellulose content and the decomposition rule were studied. The strain with the most efficient degradation effect on natural cellulose in forest litter was selected. The growth of fungi was observed by scanning electron microscopy (SEM). The hydrolytic circles indicated the activity of cellulase produced by the fungi, and it implied that the fungi could degrade cellulose. The results showed that eight strains were able to degrade cellulose. The strain A2 (Peniophora incarnate) showed the highest CI, while A4 (Sarocladium strictum) was most capable of degrading holocellulose in various litter substrates. The SEM micrographs revealed that A4 had the ability to invade leaf tissue and degrade holocellulose in leaves. This study could be helpful for forest litter management, which provides a new way to cleanup forest litter using cellulose-degrading fungi.

This study aimed to develop a method for the purification of a xylanase called SMXL1 produced by Stenocarpella maydis and its biochemical characterization. The enzyme was purified using a Rotofor preparative chamber and one chromatographic step in an ion exchange column coupled to equipment FPLC. Posteriorly the protein was characterized, and its effect on the birchwood xylan degradation was determine by HPLC. The purified enzyme showed a molecular weight of 55 kDa calculated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The purification process obtained a yield of 6.5  0.3 %. The activity was stable at a pH range of 4 to 10 and temperatures of 45 to 60 °C. The optimum values of temperature and pH were 55 °C and 4, respectively. The Michaelis constant (Km) value was 2.61 mg/mL and the Vmax was 3.02 µmol/mL/min using birchwood xylan as substrate and the Michaelis-Menten equation. The enzyme is inhibited by the cations Mn2+ and by Fe3+ and degrades the birchwood xylan being the principal products the xylobiose and the xylose. This work is the first report of the purification and biochemical characterization of a xylanase called SMXL1 produced by S. maydis.

In order to facilitate the application of wood vinegar in the mushroom industry, a framework was developed to reveal the individual and interactive effects of chemical groups in wood vinegars on Pleurotus ostreatus mycelium growth. By a series of refining and separating methods, the crude wood vinegar samples were processed and separated into six subgroups with distinctive component concentrations in each. Adding the wood vinegar subgroups into the culturing medium resulted in differences in mycelium growth. Analysis of variance was performed on the differences to evaluate the effects of seven chemical groups on mycelium growth. The enhancing effects of groups of chemicals were (ranked by effect) alcohols > esters > aldehydes; the inhibiting groups of chemicals were phenols > ketones > acids. The principle inhibitory chemicals in the wood vinegars were most likely 1,2-benzenediol, 2-methyl phenol, and 4-ethyl-2-methoxyphenol. The synergistic effects between acids and phenols and between acids and ketones were confirmed. By these effects, the inhibiting chemicals interacted synergistically as mycelium growth promoters.

Forests represent a substantial part of global socio-economy platforms. As the wood-based industry contributes large revenue to Malaysia’s economy, the readiness of Peninsular Malaysia towards sustainable wood-based industry was measured based on the different types of wood processing industries and Sustainable Forest Management (SFM) practice. Surveys (1,447) from all operating timber mills according to their raw materials type for wood products processing in Peninsular Malaysia were analyzed using multiple correspondence analysis (MCA). Results showed that the sustainable practice in wood industry by SFM practitioners and non-practitioners were similar. All industries are using outdated technologies and consume local raw materials in producing wood products. The furniture industry is largely aware of SFM and consumes the least amount of logs to produce furniture.

African blackwood (Dalbergia melanoxylon) is known as an indispensable material for the production of musical instruments, e.g., clarinets, oboes, and piccolos. The authors focused on the biological performance of African blackwood and other local Tanzanian species in order to collect preliminary data for developing further uses for these local timbers. Five local species, including African blackwood, were exposed to both subterranean termites (Coptotermes formosanus) and two wood decay fungi (White rot fungus (Trametes versicolor) and Brown rot fungus (Fomitopsis palustris)) according to Japanese standard test methods. African blackwood heartwood had high durability against both termite and fungal attacks, as well as the highest air-dried density of all test species. Some species also indicated a higher durability, even though they had a lower density than African blackwood heartwood. The authors showed the importance of heartwood extractives in terms of biological performance for the local Tanzanian timbers. The authors findings suggested that African blackwood heartwood was clearly useful as a high-durability material in addition to current major applications. The potential of the other local species was also suggested in terms of further timber utilization. These results presented fundamental information about sustainable forest management based on the effective utilization of local timbers.

Linen/viscose blended yarns provide unique properties, but the quality and cost of the fabric composed of the blended yarns are affected by the amount of linen fibers. The existing methods of detecting blending ratio are microscopy or specific component dissolution, which is time-consuming and inconvenient. This study considers the possibility of rapid and simple determination of linen content by the near infrared (NIR) method. A set of linen/viscose powdered blends with 11 different ratios was fabricated. For each sample, 10 sets of spectra were collected by Fourier transform (FT)-NIR spectrometer. A total of 110 spectra sets were generated, in which 60 were used for calibration and 50 for validation. There were verified differences in NIR peaks assigning to representative chemical bonds in cellulose. With the chemometric analysis, a partial least squares (PLS) model was established to predict the linen content in a blended sample. With a combination of smoothing, baseline offset, and multiplicative scatter correction processing of the spectral data, the established PLS model was further improved to achieve a standard validation error of only 1.182% and SD value of the predicted linen content less than 0.2, which indicated the accuracy of the developed method.

The solid digestate from high solid anaerobic digestion was used as growth medium for seeding production. The garage-type dry fermentation system using bundled rice straw and swine manure was performed to obtain solid digestate. The addition of solid digestate addition greatly influenced the properties of the growth medium. The bulk density increased and the total porosity, pH, and electrical conductivity (EC) values were decreased with the reduction of solid digestate. The solid digestate-based media had a bulk density < 0.3 g/cm3, total porosity > 70%, air filled porosity ~ 3%, water holding porosity > 60%, EC < 3 mS/cm, and 6.5 < pH < 8. Those properties almost satisfied the essential requirements of nursery substrate. Also, the concentrations of nutrients and heavy metals of the substrate exhibited a positive relationship with solid digestate addition, and they are all within acceptable ranges for plant growth. When the addition of solid digestate was 50% (v/v), the germination rate of tomato seeding cultivated in that solid digestate-based growth medium reached 85%. These findings showed that the solid digestate from the high solid anaerobic digestion could be successfully applied in the seeding nursery and merit consideration for industrial applications.

Waste rubber retains good elasticity and can be regenerated for use in special applications. In this research, wood fiber composites were made with waste tire powders (WTPs) as functional fillers. The physical-mechanical properties of the wood-rubber composite (WRC) panels, i.e., inner bond (IB) strength, static bending modulus (MOE), strength (MOR), and thickness swelling (TS) were assessed. The surface micro-morphology of the WRC panels was quantitatively analyzed and was graphically simulated with Matlab software. The results showed that WTPs decreased the mechanical strength and modulus of the hybrid composites, which was caused by the weak fiber/WTP interfacial adhesion. The addition of WTPs roughened the surface of composite panels. However, WRC panels showed improved hygroscopic stability and flexibility compared to pure wood fiber composites. Sanding can flatten the rougher WRC panel surface; however, it brings tiny pits to the surface that are caused by loss of rubber powders. Surface overlaying with resin impregnated paper was found to be effective to cover the tiny pits. This study showed that it is feasible to make value added rubber filled wood fiber composites with satisfactory performance.

As the main production unit of plywood, the surface defects of veneer seriously affect the quality and grade of plywood. Therefore, a new method for identifying wood defects based on progressive growing generative adversarial network (PGGAN) and the MASK R-CNN model is presented. Poplar veneer was mainly studied in this paper, and its dead knots, live knots, and insect holes were identified and classified. The PGGAN model was used to expand the dataset of wood defect images. A key ideal employed the transfer learning in the base of MASK R-CNN with a classifier layer. Lastly, the trained model was used to identify and classify the veneer defects compared with the back- propagation (BP) neural network, self-organizing map (SOM) neural network, and convolutional neural network (CNN). Experimental results showed that under the same conditions, the algorithm proposed in this paper based on PGGAN and MASK R-CNN and the model obtained through the transfer learning strategy accurately identified the defects of live knots, dead knots, and insect holes. The accuracy of identification was 99.05%, 97.05%, and 99.10%, respectively.

The microscopic pore structure of wood is an important factor that affects its macroscopic properties. In this study, an oak sample was used for pore structure characterization. X-ray computed tomography imaging was carried out, and the scanning results (a multi-layer two-dimensional planar image) were rendered using Avizo software (a three-dimensional stereo image). A digital image processing method was used to identify the characteristics of the three-dimensional pore structure features and to calculate the characteristic parameters, i.e., the porosity (volume/surface), pore area and volume, pore size distribution, and the connectivity. The 27 mm3 oak sample had the following characteristics: a pore size which ranged from 8.56 µm to 1262.84 µm; a pore volume of 1.01 × 1010 µm3; a pore area and volume porosity of 1.12 × 109 µm2 and 37.6%, respectively; a surface porosity range of approximately 36.1% to 39.1%; a pore diameter for axial connection ranging from approximately 164.57 µm to 1262.84 µm; and had corresponding proportions of the pore area and volume of approximately 74.4% and 67.3%, respectively. This information provided useful structural data for the construction of future models.