Abstract
The aim of this study was to investigate degraded birch trees (Betula pendula Roth) that suffered from a harmful fungus called Piptoporus betulinus. The main chemical analysis of B. pendula degraded by the fungus, included the holocellulose, alpha-cellulose, and lignin contents and was determined in cold and hot water and alcohol-benzene solubility in 1% NaOH mixtures. This fungus caused B. pendula to lose mass and chemical properties. The declining amount of holocellulose mass loss was 6.7% according to the holocellulose test. This decrement caused the quality of the birch holocellulose to decline. The total loss difference was 9.8% according to the alkaline solubility analysis of the 1% NaOH test and 14.3% according to the density analysis of the test. The loss difference was 4.2% according to the alcohol-benzene analysis of the test.
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Chemical Analysis of Birch Tree (Betula pendula Roth) Degraded by Fungus
Osman Camlibel *
The aim of this study was to investigate degraded birch trees (Betula pendula Roth) that suffered from a harmful fungus called Piptoporus betulinus. The main chemical analysis of B. pendula degraded by the fungus, included the holocellulose, alpha-cellulose, and lignin contents and was determined in cold and hot water and alcohol-benzene solubility in 1% NaOH mixtures. This fungus caused B. pendula to lose mass and chemical properties. The declining amount of holocellulose mass loss was 6.7% according to the holocellulose test. This decrement caused the quality of the birch holocellulose to decline. The total loss difference was 9.8% according to the alkaline solubility analysis of the 1% NaOH test and 14.3% according to the density analysis of the test. The loss difference was 4.2% according to the alcohol-benzene analysis of the test.
Keywords: Betula pendula Roth; Birch tree; Mass loss; Wood degradation; Chemical analysis
Contact information: Department of Material and Material Processing, Kirikkale Vocational School, Kırıkkale University, Kırıkkale, Turkey; *Corresponding author: osmancamlibel@kku.edu.tr
INTRODUCTION
Although Turkey has 20 million hectares of forest areas, which is roughly 27% of the country’s land area, wood biomass is not used efficiently enough and the demand for raw materials increases the need for wood-based products (Karayılmazlar et al. 2011). Betula pendula Roth is the most important forest tree and is imported from the north-west district of Ukraine (Hynynen et al. 2010).
Betula pendula is known as a white birch wood and is classified in the mature trees group. The air mass specific gravity of B. pendula is 0.62 g/cm3 (Çakıroğlu et al. 2011). The mean dry density of B. pendula ranges from 0.480 to 0.550 g/cm3 (Heräjärvi 2001). The mechanical resistance of B. pendula is low but its physical strength properties are good. It is an easily processable wood. However, B. pendula timber undergoes cracking and deformation in dry open air. It is weak in open air and immediately decays. Therefore, this type of wood is more widely used for aesthetic and design purposes.
The biological degradation of lignocellulosic materials, especially woody biomass (all lignocellulosic materials) by wood-rot fungi basidiomycetes, acts as a necessary act in the carbon circle. Holocellulose is an important carbon/energy resource for the growing of many fungi. Brown rot fungi are perhaps the most important agents involved in the biodegradation of all lignocellulosic materials (Arantes and Goodell 2014).
The first attack by the brown rot fungi degradation includes cleavage of glycosidic bonds, depolymerization of wood polysaccharides, and degradation of pectic substances. Correspondingly, intramolecular hydrogen bonding within cellulose is reduced, while the presence of phenolic groups is increased (Arantes et al. 2012). Arantes and Goodell (2014) have studied the brown-rot-fungi biochemical operation step related to the biodegradation of lignified herb of yearly cell walls.
Incipient brown-rot fungus processes are localized in outer cell wall regions allocated with the middle lamellae, primary cell walls, and outer secondary cell walls. Despite this, white-rot fungus processes are evenly distributed in the tracheid cells, even if the cells in one thin section are affected to very different extents (Fackler et al. 2012).
Cellulose is the basic structural component of the plant cell wall, as well as being the most plentiful polysaccharide on Earth. Cellulose is an important renewable biological material. Basidiomycetous fungi are among the most important degraders of wood because numerous basidiomycetous fungi grow on dead wood or litter, an environment that is rich in cellulose (Baldrian and Valaskova 2008). The fungal attack is liable for important reductions in mechanical and physical of wood properties, and it has effects on moisture content, electrical conduction acoustics, convection, elasticity, and plasticity in wood (Cowling 1961; Schmidt 2006).
Piptoporus betulinus grows equally well on heartwoods of sycamore, basswood, and birch, on sapwoods of white oak, butternut, and osage orange, and on white portions of red cedar wood (Lafuze 1937). Sporophores of the birch fungus Piptoporus betulinus have only been observed on species belonging to the Betula genus (Henningsson 1965). Fagus sylvatica L. (beech) wood block has been degraded under laboratory conditions by the white-rot fungi (Trametes versicolor, Pleurotus ostreatus, and Lentinus edodes). The weight loss amounts of the wood block of Fagus sylvatica were 51, 27, and 24%, respectively (Faix et al. 1991). The most important wood decaying fungi are the brown rot fungi. Brown rot fungi degrade wood polysaccharides while partially changing the lignin. As a result of this kind of decay, the wood shrinks, shows a brown discolouration owing to oxidized lignin, and cracks into roughly cubical pierces (Gilbertson 1980; Monrroy et al. 2001).
Living B. pendula is weak and affected by the fungus. After the tree dies, the decaying continues in the wood core and bark. Pine sap-wood blocks were exposed to brown-rot fungi for 1, 2, 3, and 4 months by Irbe et al. (2006). According to the results, the most notable feature is the preferred degradation of mannose both by brown-rot fungi (P. placenta with 80.9% weight loss) and brown-rot fungi (C. puteana with 77.5% weight loss) in comparison to the reference. Kahl et al. (2017) indicated that fungi, beetles, and enzymes play important roles for wood decomposition. According to the study, a mix of different tree species in deadwood enrichment strategies might be most effective for promoting species diversity in the degrading organisms.
Higher Basidiomycota have been used in natural drugs throughout the world for hundreds of years. Fomitopsis betulina (previously Piptoporus betulinus) is an example of this kind of fungi, which give rise to brown rot of birch wood (Pleszczynska et al. 2017). In natural earth, wood undergoes biological decay, firstly by white rot fungi, brown rot fungi, and soft rot fungi. Basidiomycetes have responsibility for the majority of wood decay, for instance mass loss and strength loss (Eriksson et al. 1990; Zabel and Morrell 1992; Mohebby 2003; Schmidt 2006). Schmidt et al. (2012) collected samples of infected
trees living in the city, which included fruit bodies of wood decay fungi. They researched causal agents of wood rot. Song et al. (2012) determined that a competitive mutual effect between fungal species can promote colonization and that this can have an important result on the conclusion of wood degradation.
The B. pendula tree is common in Europe, Asia, and America. Annual white to brownish fruiting bodies of the species can be found on trees in the northern hemisphere (Pleszczynska et al. 2017). Arantes and Goodell (2014) studied the current understanding of brown-rot fungal biodegradation mechanisms.
The work of Valaskova and Bandrian (2006) shows that P. betulinus fungi perform fast hydrolysis of lignocellulose due to their hydrolytic enzymes with relatively expansive substrate specificities. Ujangr (1993) investigated the ratio and percentage of weight loss caused by decay of white-rot and brown rot fungi. According to study, average losses were is the range 27.6 to 34.4% due to the fungi. Brown rot fungi affect all softwoods, where it degrades both hemicellulose and cellulose but leaves lignin intact as a residue (Wong and Wilkes 1988; Rayner and Boddy 1988). Van der Wal et al. (2015) have shown that wood moisture content contributed particularly to promoting sap-wood decay in early decay phases, whereas fungal community composition and species riches were the best determinative for mass loss in the later stages.
The forests of Turkey alone are not enough to supply the increasing demand of raw materials needed for wood-based products. B. pendula is used as the raw material in wood- based products. B. pendula wood has a deteriorated structure and mass loss after being biologically affected by fungi. Moreover, this fungus affects the living trees in the forest. In the present paper, the author shows the analysis results of the degraded B. pendula wood. This study considers the product productivity and the in-production cost calculation of wood-based products.
EXPERIMENTAL
Chemical Usage
Chemical formula, CAS number, molecular weight of chemicals used in chemical analysis were as follows: Sodium Chlorite CAS number. 7758-19-2, chemical formula: ClNaO2, molecular weight: 90.44g/mol. Benzene: CAS number: 71-43-2. chemical formula: C6H6, molecular weight: 78.11g/mol. Sulfuric acid; CAS number: 7664-93-9. chemical formula: H2SO4, molecular weight: 98.079 g/mol Sodium hydroxide: CAS Number:1310-73-2. chemical formula: NaOH. Molecular weight:39.997g/mol.
Materials
The biodegraded Betula pendula woods were imported from (Sunrise Company, Western Carpathian Region, Ukraine) Ukraine to Turkey by ship. The diameters and the lengths of the control and degraded B. pendula ranged from 10 to 15 cm and 75 to 100 cm, respectively. Figure 1 shows the forest map of Ukraine.
Piptoporus betulinus is a brown-rot fungus. This fungus only uses weak, old, dead trees as hosts (Lee et al. 2010). Henningsson (1965) reported that as a result of P. betulinus attacking birch wood under favourable conditions, a maximum weight loss of up to approximately 71% occurs. Valaskova and Baldrian (2006) reported that it causes a fast mass loss of birch wood or other lignocellulose substrates
Fig. 1. Distribution map of Betula pendula species in Ukraine Forest; this map was acquired from the Forest in the Internet Encyclopedia of Ukraine database
Baldrian and Gabriel (2002) explained that this fungus species is a hardwood-specific parasite of Betula pendula (Betula spp.) trees in northern temperate forests and causes a fast wood decay. It is also one of the most common brown-rot species in Central Europe. Bell and Burnett (1966) reported that it can depolymerize cellulose.
Ujangr et al. (2007) reported the weight loss for 60 days in the mini test block of Betıula pendula (1 cm x 3 cm) timber in their study. According to the research, they were decayed with soft-rot fungi (Chaetomium globosum), white-rot fungi (Corilous versicolor), and brown rot fungi (Coniophora putana). As a result of the research, soft rot fungi (Chaetomium globosum) caused 45.5% mass loss, white rot fungi (Coriolous versicolor) caused 35.4% mass loss, and brown rot fungi (Coniophora putana) caused 29.5% mass loss.
In this study, chemical compounds and the mass losses of the biodegraded B. pendula wood were analyzed by chemical methods.
Fig. 2. Piptoporus betulinus fungus on trunk of Betula pendula tree
Methods
The density analysis
This analysis was performed according to the TS EN 323 (2008) standard. The experimental results are given in Table 1. The analyzed samples are shown in Fig. 3.
Fig. 3. Betula pendula density analysis sample
The chemical analysis
The wood chips samples ranged from 1.8 to 2.0 cm in length and from 2 to 3 mm in thickness. The samples are shown in Fig. 4.