A Review on Promising Approaches for Liquid Permeability Improvement in Softwoods

The low liquid permeability of refractory wood species such as Norway spruce [Picea abies (L.) Karst.] and white Fir (Abies alba) is related mainly to the aspiration of bordered pits during wood drying. The resulting low permeability complicates treatments with liquid preservatives or wood modification substances. This article provides a literature review on various mechanical and biotechnological approaches that were developed for improving liquid permeability. In this context, we focus on the incubation of Norway spruce wood with a white rot fungus, Physisporinus vitreus (Pers.) P. Karst. The process is termed "bioincising" and results in a significant increase in wood permeability. This is most probably caused by the selective degradation of bordered pit membranes and simple pits of xylem ray parenchyma during the initial period of wood colonization. Subsequently, we discuss how bioincising could be a potential pretreatment method for wood preservation and selected wood modification substances. Considering that these wood modification systems require specific penetration depths for optimal performance, we discuss the capability of bioincising to enhance permeability at the required penetration depths. In this regard, we propose a terminology for better differentiation of penetration depths by liquid substances into the wood

Integrated control of wood destroying basidiomycetes combining Cu-based wood preservatives and Trichoderma spp

[EN] The production of new generation of wood preservatives (without addition of a co-biocide) in combination with an exchange of wood poles on identical sites with high fungal inoculum, has resulted in an increase of premature failures of wood utility poles in the last decades. Wood destroying basidiomycetes inhabiting sites where poles have been installed, have developed resistance against wood preservatives. The objective of the in vitro studies was to identify a Trichoderma spp. with a highly antagonistic potential against wood destroying basidiomycetes that is capable of colonizing Cu-rich environments. For this purpose, the activity of five Trichoderma spp. on Cu-rich medium was evaluated according to its growth and sporulation rates. The influence of the selected Trichoderma spp. on wood colonization and degradation by five wood destroying basidiomycetes was quantitatively analyzed by means of dry weight loss of wood specimens. Furthermore, the preventative effect of the selected Trichoderma spp. in combination with four Cu-based preservatives was also examined by mass loss and histological changes in the wood specimens. Trichoderma harzianum (T-720) was considered the biocontrol agent with higher antagonistic potential to colonize Cu-rich environments (up to 0.1% CuSO4 amended medium). T. harzianum demonstrated significant preventative effect on wood specimens against four wood destroying basidiomycetes. The combined effect of T. harzianum and Cu-based wood preservatives demonstrated that after 9 months incubation with two wood destroying basidiomycetes, wood specimens treated with 3.8 kg m-3 copper-chromium had weight losses between 55±65%, whereas containers previously treated with T. harzianum had significantly lower weight losses (0±25%). Histological studies on one of the wood destroying basidiomycetes revealed typical decomposition of wood cells by brown-rot fungi in Cu-impregnated samples, that were notably absent in wood specimens previously exposed to T. harzianum. It is concluded that carefully selected Trichoderma isolates can be used for integrated wood protection against a range of wood destroying basidiomycetes and may have potential for integrated wood protection in the field.The authors are pleased to acknowledge the financial support by the Swiss CTI (Project No. 17001.1 PFLS-LS).Ribera, J.; Fink, S.; Bas Cerdá, MDC.; Schwarze, FWMR. (2017). Integrated control of wood destroying basidiomycetes combining Cu-based wood preservatives and Trichoderma spp. PLoS ONE. 12(4). https://doi.org/10.6084/m9.figshare.4743061S12

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

Influence of Soil Characteristics on Wood Biodeterioration by Brown Rot Fungi

Soil conditions can directly influence the inoculum potential of wood decay fungi, which is likely to be a major factor in the premature failure of utility poles across Europe. The objective of our study was to assess the influence of soil pH, humic acid and iron on wood decay. For this purpose, we incubated Fe-impregnated wood specimens on artificial medium to evaluate the influence of the metal on the activity of brown rot fungi. Moreover, the impact of Cu-leaching from impregnated wood specimens that were exposed to humic acid solutions was measured. In addition, weight losses caused by brown rot fungi in impregnated wood pole segments and stiffness (Young’s modulus of Elasticity) of Cu-impregnated wood specimens were quantified. The pH measurements showed that the soil samples were slightly acid (pH = 6.7 ± 0.7). In comparison to non-impregnated controls, the Fe-impregnated samples significantly increased weight losses by brown rot fungi (>30–40%). In the presence of humic acid the release of copper from chromium-free wood preservatives (up to 143.34 mg L−1) was enhanced. Weight losses in impregnated wood segments by brown rot fungi ranged from 5.3 to 20.4%. The recorded reduction in stiffness by brown rot fungi ranged from approximately 3.96 to 55.52% for Cu-impregnated wood specimens after 12 weeks. Our study shows that the pH, humic acid, iron content and selected wood preservatives greatly influence susceptibility of impregnated wood to brown rot fungi during ground contact

Antimicrobial effect of fungal melanin in combination with plant oils for the treatment of wood

Microbial deterioration of wood has gradually destroyed precious historic musical instruments. The Serpentino (English: serpent/little snake) is a wind instrument used for over 400 years and is considered the godfather of modern instruments such as the saxophone and the tuba. Many original instruments have been totally destroyed due to colonization and degradation by bacteria and fungi. Reconstructing the serpent in particular and other ancient instruments in general requires the preservation of wood against bio-deterioration. Conventional chemical preservatives based on copper and boron compounds have been used in the wood processing industry; however, they are not ideal for protecting musical instruments and may pose a negative impact on the health and safety of musicians with direct mouth contact. Non-biocidal preservatives, such as plant oils, have attracted a lot of attention. Herein, we report the antimicrobial efficacy of plant oils, alone and in combination with fungal melanin, for protecting walnut wood that is used to make the serpent, against oral bacteria and wood-decay fungi. Linseed and tea tree oils were found to have a strong antibacterial effect, reducing the survival rate of Streptococcus mutans, a bacterium commonly found in human saliva, to below 1%. Impregnation of wood with plant oils and melanin significantly increased the antibacterial effect when compared to that of the oil(s) alone. A satisfactory antifungal effect was also achieved after 2 weeks as indicated by a reduction (< 10%) in the survival rate of Chaetomium globosum on the radial longitudinal wood surface. In addition, the treated wood samples absorbed less water than the untreated wood, and maintained their dimensions at different humidity conditions, highlighting the potential of this approach for wood protection.ISSN:2296-801

Hybrid Adsorbent Materials Obtained by the Combination of Poly(ethylene-alt-maleic anhydride) with Lignin and Lignosulfonate

Abstract: Lignin is one of the most available biomass products, but its potential for the development of functional materials has yet to be unleashed. Here, the modification of lignin and lignosulfonate with poly(ethylene-alt-maleic anhydride) [P(E-alt-MA)], a functional polymer of wide industrial use, is accomplished by means of a simple esterification reaction. As a result, hybrid adsorbent materials for water purification can be obtained, which were thoroughly characterized. The combination of P(E-alt-MA) with lignin increased hydrophilicity of the latter, making it dispersible in aqueous environments, while with lignosulfonate it gave rise to a water-insoluble, thus easily recoverable, product. The adsorption properties of the resulting products have been tested against a model water pollutant (methylene blue), demonstrating remarkable adsorption speed (in the order of minutes), adsorption efficiency and stability over a wide range of pH (2–12). Moreover, after the incorporation of magnetite nanoparticles by in situ synthesis, adsorbent materials able to be magnetically recovered were developed. Graphical Abstract: [Figure not available: see fulltext.]

Effect of Trichoderma-enriched organic charcoal in the integrated wood protection strategy.

The gradual elimination of chromium from wood preservative formulations results in higher Cu leaching and increased susceptibility to wood decay fungi. Finding a sustainable strategy in wood protection has become of great interest among researchers. The objective of these in vitro studies was to demonstrate the effect of T-720-enriched organic charcoal (biochar) against five wood decay basidiomycetes isolated from strongly damaged poles. For this purpose, the antagonistic potential of Trichoderma harzianum (strain T-720) was confirmed among other four Trichoderma spp. against five brown-rot basidiomycetes in dual culture tests. T-720 was genetically transformed and tagged with the green fluorescent protein (GFP) in order to study its antagonistic mechanism against wood decay basidiomycetes. It was also demonstrated that T-720 inhibits the oxalic acid production by basidiomycetes, a well-known mechanism used by brown-rot fungi to detoxify Cu from impregnated wood. Additionally, this study evaluated the effect of biochar, alone or in combination with T-720, on Cu leaching by different preservatives, pH stabilization and prevention of wood decay caused by five basidiomycetes. Addition of biochar resulted in a significant Cu binding released from impregnated wood specimens. T-720-enriched biochar showed a significant reduction of wood decay caused by four basidiomycetes. The addition of T-720-enriched biochar to the soil into which utility poles are placed may improve the efficiency of Cr-free wood preservatives

Cu-based wood preservatives retained by the wood specimens (EN113).

<p>Cu-based wood preservatives retained by the wood specimens (EN113).</p

Effect of <i>Trichoderma</i> species, T-685 and T-720, on preventing mass loss from basidiomycetes after 12 weeks incubation on wood.

<p>Different letters indicate significant differences between the <i>Trichoderma</i> treatments and the controls. Shared numbers indicate the subgroups (wood destroying basidiomycete) of the analysis after the Tukey’s HDS test (<i>p</i><0.05). Data represented as mean ± SD of three biological replicates.</p