FIG 1 - uploaded by Miia R Mäkelä
Content may be subject to copyright.
Simplified model of plant cell wall structure. (A) The structure consists of three main layers: the middle lamella and the primary and secondary walls. (A and B) The main polysaccharides and lignin which form the surrounding structure for the plasma membrane are presented in the primary (B) and secondary wall (C). The lignin content in the primary cell wall (not illustrated) varies considerably depending on the plant species (Table 1). The illustrations are not to scale.
Source publication
Basidiomycete fungi subsist on various types of plant material in diverse environments, from living and dead trees and forest litter to crops and grasses and to decaying plant matter in soils. Due to the variation in their natural carbon sources, basidiomycetes have highly varied plant-polysaccharide-degrading capabilities. This topic is not as wel...
Context in source publication
Context 1
... use for plant polysaccharide degradation is in its infancy compared to ascomycete studies, due largely to the traditional and well-established industrial relevance of several ascomycetes. Since the enzyme sets of basidiomycetes are likely to reflect adaptation to their unique natural niches, basidiomycetes contain a huge potential for applications in various industries, which has so far remained largely unexplored. As mentioned above, our knowledge of basidiomycetes regarding their ability to decompose plant polysaccharides is limited compared to the wealth of information on ascomycetes. Before the genomics era, functional analyses of purified enzymes and expression studies of the corresponding genes were the main approaches for characterization of the fungal CAZyme machinery. However, these methods are laborious and cannot provide a full overview of a fungal CAZyme arsenal. More detailed insights into the entire polysaccharide-degrading capability of fungi with interesting ecologies have been obtained through genome sequencing (6–15) together with transcriptome and proteome analyses (16– 18). However, only by combining these omics data with biochemical characteristics of the enzymes can we complete our understanding of the plant cell wall polysaccharide degradation ability of basidiomycete fungi. This review explores the enzymatic potential of basidiomycetes from different biotopes and focuses on their ability to depolymer- ize cellulose, hemicelluloses, and pectin. The basidiomycetes are compared to species belonging to Aspergillus , which is one of the most extensively studied ascomycete genera, to dissect differences in their strategies for plant polysaccharide degradation. While there is also a large diversity among the ascomycete fungi, the aspergilli are among the few ascomycetes that have been studied with respect to the degradation of all plant polysaccharides (19). First, a comparison of the putative CAZyme-encoding genes found in the genomes of wood- and litter-decomposing basidiomycetes, plant pathogens, and ectomycorrhizal (ECM) fungi gives insight into their plant cell wall polysaccharide-degrading enzyme potential. Second, previously characterized CAZymes isolated from basidiomycetes are compared to those from genomic stud- ies. Finally, the so far poorly addressed regulatory mechanisms of basidiomycetes in plant cell wall degradation are reviewed. The three most important polysaccharide building blocks of plant cell walls are cellulose, hemicellulose, and pectin. Together with lignin, an aromatic heteropolymer, they form a degradation-resis- tant and functional complex that provides rigidity and structure to the plant and protects the cells from microbial attack. The plant cell wall consists of three main layers: the middle lamella and the primary and secondary walls (Fig. 1A) (20, 21). Each of these layers has a unique structure and chemical composition that also differ strongly between plant species, tissues, and the growth phase of the plant (Fig. 1B and C). The major differences in the chemical compositions of softwood (e.g., pine and spruce) and hardwood (e.g., birch, aspen, and oak) are in the structure and content of hemicelluloses (Table 1). Hemicelluloses in softwood consist mainly of galactoglucomannans, whereas the majority of hardwood hemicelluloses are glucuronoxylans (Table 1) (20). On average, softwood has higher lignin content than hardwood, while the amount of cellulose in softwood is smaller than that in hardwood (Table 1) (20). The chemical compositions of cell walls in flowering plants also vary (Table 1). Monocots, i.e., grasses, are considered the most important renewable-energy crops, and their primary cell wall consists mainly of cellulose and hemicelluloses, whereas their secondary walls contain larger amounts of cellulose, a different composition of hemicelluloses, and significant amounts of lignin (Table 1) (22). The primary cell walls of dicots differ from those of grasses by their low xylan and high xyloglucan and mannan con- tents (Table 1) (22). In addition, the amount of pectin is notably larger in dicots than in grasses (Table 1). The secondary wall of dicots is composed of cellulose, hemicelluloses, and lignin (Table 1) (22). Cellulose, found in both the primary and secondary cell walls, is the most abundant polysaccharide in plant matter (40 to 45% dry weight) and gives the plant cell wall its rigid structure (20). Re- peating units of  -1,4-linked D -glucose form linear cellulose chains, which are held together by intermolecular hydrogen bonds and create linear crystalline structures (microfibrils) (23) and less crystalline, amorphous regions. The ratio of crystalline to amorphous regions varies between the layers of primary and secondary cell walls as well as between plant species. Cellulose microfibrils are more irregularly ordered in the outer layer than in the inner layer of the primary cell wall, where they are perpendicularly ori- ented (Fig. 1). Furthermore, the angles and directions of the cellulose microfibrils vary among the three sublayers (sublayer 1 [S 1 ] to S ) of the secondary plant cell wall (20, 21). Hemicelluloses (20 to 30% plant dry weight) support the structure of the cellulose microfibrils in the primary and secondary walls of plant cells (20). There are four types of amorphous hemicellulose structures with different main monosaccharide units in their hemicellulose backbone. Xylan is the most common hemicellulose polymer with a  -1,4-linked D -xylose backbone. Other hemicelluloses are xyloglucan (  -1,4-linked D -glucose), found mainly in the primary walls;  -glucan (  -1,3;1,4-linked D -glucose); and mannan (  -1,4-linked D -mannose) (21). Xylan, xyloglucan, and mannan backbones are decorated with branched monomers and short oligomers consisting of D -galactose, D -xylose, L -arabinose, L -fucose, D -glucuronic acid, acetate, ferulic acid, and p -cou- maric acid that are cleaved by debranching enzymes (24). Pectin is a noncellulosic polysaccharide containing galacturonic acid that provides additional cross-links between the cellulose and hemicellulose polymers. It is found mainly in plant primary cell walls and middle lamella (25). The pectin concentration in the middle lamella is high at an early stage of plant growth, but the concentration decreases during lignification (20). The simplest pectin structure is homogalacturonan (HG), which is a linear polymer of ␣ -1,4-linked D -galacturonic acid residues that can be methylated at the C-6 carboxyl group and acetylated at the O-2 or O-3 position. Xylogalacturonan (XGA) is a substituted galacturonan that has  -1,3-linked D -xylose residues attached to the galacturonic acid backbone. The second substituted galacturonan is rhamnogalacturonan II (RG-II). The structure of RG-II is more complex than the structure of XGA. Altogether, 12 different glycosyl residues, e.g., 2- O -methyl xylose, 2- O -methyl fucose, aceric acid, 2-keto-3-deoxy- D -lyxo heptulosaric acid, and 2-keto-3-de- oxy- D -manno-octulosonic acid, can be attached to the galacturonic acid backbone (25). The most complex pectin structure, rhamnogalacturonan I (RG-I), has a backbone of alternating D galacturonic acid and L -rhamnose residues, with branching structures consisting of D -galactose and L -arabinose chains attached to the L -rhamnose residues. An overview of the known fungal plant-polysaccharide-degrading or -modifying enzymes is presented in Table 2. The enzymes are divided according to their substrates, and their EC numbers, abbreviations, and corresponding CAZyme families (2) are also shown. The main enzymes that hydrolyze cellulose, so-called classical cellulases, are endoglucanases, exoglucanases, and  -glucosidases (BGLs).  -1,4-Endoglucanase (EG) (EC 3.2.1.4) cleaves within the cellulose chains to release glucooligosaccharides (Fig. 2A). Exoglucanases or cellobiohydrolases (CBHs) release cellobiose from the end of the cellulose chains. The two types of cellobiohydrolases, CBHI and CBHII (EC 3.2.1.176 and EC 3.2.1.91, respectively), degrade cellulose from either the reducing or the nonreducing end, respectively, with different processivities, i.e., the efficiency of the sequential hydrolysis of the  -1,4-glycosidic bonds by the cellulase before the dissociation of the enzyme from the substrate (26). BGL (EC 3.2.1.21) releases the smallest unit, glucose, from shorter oligosaccharides. Recently, oxidoreductive cleavage of the cellulose chain has been reported. Cellobiose dehydrogenase (CDH) (EC 1.1.99.18) and lytic polysaccharide monooxygenases (LPMOs) participate in cellulose degradation in combination with cellulases (Fig. 2A) (27, 28). CDH is the only known extracellular flavocytochrome that oxidizes cellobiose and cellooligosaccharides to the corresponding lactones (29, 30). The exact role of CDH in lignocellulose degradation is still unclear, although there is evidence of its relevance in both the cellulolytic and lignin-modifying machinery of fungi (29, 30). The ability of CDH to produce hydroxyl radicals through Fenton chemistry supports its role in lignin modification, while oxidation of cellobiose together with the production of electrons for LPMO-catalyzed cellulose depolymerization demonstrate the participation of CDH in the degradation of cellulose (29, 31, 32). LPMOs are copper monooxygenases that catalyze the direct oxidation of the cellulose chain leading to cleavage of the glycosidic bond (28, 31, 32). Moreover, fungal LPMOs can be divided into at least three classes according to their sequence similarity and specific activities toward cellulose (33). Type 1 LPMOs catalyze oxidation of the glucose unit at the C-1 position, resulting in the formation of aldonic acids at the reducing end of the cellulose chain (28, 32). Type 2 LPMOs generate ketosugars at the nonreducing end of the cellulose chain by oxidizing at the C-4 position (34). LPMOs of type 3 are not as specific ...
Citations
... The carbohydrate-active enzymes (CAZymes) constitute a broader enzyme group that includes the glycosyltransferases (GTs), glycoside hydrolases (GHs), polysaccharide lyases (PLs), carbohydrate esterases (CEs), carbohydrate-binding modules (CBMs), and auxiliary activities (AAs) (Lombard et al., 2014). These are mainly involved in the degradation/rearrangements of glycosidic bonds in carbohydrates (Rytioja et al., 2014). However, the increasing industrial applications of CAZymes demand the exploration of new microbial strains for more diverse CAZymes. ...
A newly isolated bacterium Acinetobacter pittii S-30 was recovered from waste-contaminated soil in Ranchi, India. The isolated bacterium belongs to the ESKAPE organisms which represent the major nosocomial pathogens that exhibit high antibiotic resistance. Furthermore, average nucleotide identity (ANI) analysis also showed its closest match (>95%) to other A. pittii genomes. The isolate showed metal-resistant behavior and was able to survive up to 5 mM of ZnSO4. Whole genome sequencing and annotations revealed the occurrence of various genes involved in stress protection, motility, and metabolism of aromatic compounds. Moreover, genome annotation identified the gene clusters involved in secondary metabolite production (biosynthetic gene clusters) such as arylpolyene, acinetobactin like NRP-metallophore, betalactone, and hserlactone-NRPS cluster. The metabolic potential of A. pittii S-30 based on cluster of orthologous, and Kyoto Encyclopedia of Genes and Genomes indicated a high number of genes related to stress protection, metal resistance, and multiple drug-efflux systems etc., which is relatively rare in A. pittii strains. Additionally, the presence of various carbohydrate-active enzymes such as glycoside hydrolases (GHs), glycosyltransferases (GTs), and other genes associated with lignocellulose breakdown suggests that strain S-30 has strong biomass degradation potential. Furthermore, an analysis of genetic diversity and recombination in A. pittii strains was performed to understand the population expansion hypothesis of A. pittii strains. To our knowledge, this is the first report demonstrating the detailed genomic characterization of a heavy metal-resistant bacterium belonging to A. pittii. Therefore, the A. pittii S-30 could be a good candidate for the promotion of plant growth and other biotechnological applications.
... The primary function of saprotrophic fungi is to decompose plant residues, wood as well as any organic material (Fukasawa and Matsukura, 2021;Kyaschenko et al., 2017). This implies high production of an extensive set of plant cell walls polysaccharidedegrading and ligninolytic enzymes (Rytioja et al., 2014;Van Den Brink and De Vries, 2011); so much so that fungal exploitation for the extraction of degrading enzymes at an industrial level is very extensive and has reached high technological levels (Østergaard and Olsen, 2011). This is a post-refereeing final draft. ...
... Overall, these findings are consistent with the separation found between Ascomycota and Basidiomycota based on the gene expression for carbohydrate-active enzymes reported by (TlÁskal et al., 2021). However, the large and variable plant-polysaccharide-degrading found also in Basidiomycetes had been already observed by Rytioja et al. (2014), who suggested that this pool of enzymes is not a peculiarity of Deuteromycetes Ascomycota, though the latest are conventionally known as the most active in degrading herbaceous crop residues (Thygesen et al., 2003). ...
Keywords: Saprotrophic fungi; C-Cycle; soil; metabolic adaptability; mycelium; enzymatic activity The enzyme profile of a series of fungal isolates belonging to Ascomycota and Basidiomycota was analysed for a better understanding of the functional significance of their changes in soil with a specific focus on the carbon cycle. Two synthetic populations of Ascomycota and Basidiomycota isolates were compared on the basis of their enzymatic profiles. The activities of twenty-five enzymes extracted from the mycelium of pure fungal colonies were quantified in microplates using fluorogenic substrates. The enzyme activities were divided by the dsDNA content of each fungal colony and subjected to multivariate analysis. Ascomycota and Basidiomycota differed significantly (P=0.0001) in enzyme profile. Ascomycetes showed a broader enzymatic profile than Basidiomycetes. In the latter, seven out of the twenty-five enzyme activities detected in Ascomycetes were absent, including the enzymes of phosphorus and sulphur metabolisms and alpha-galactosidase. To the contrary, many enzymes responsible for plant polysaccharide degradation, such as alpha-galactosidase, beta-mannosidase or xilosidase were detected in the isolates of both fungal phyla. This indicates likely underestimated ability of Basidiomycetes to degrade plant polysaccharides, apart from their specific ability to decompose lignin. To the contrary, the widest enzyme profile of Ascomycota and their highest enzymatic inter-and intra-genus variability indicates their higher adaptability to metabolize different crop residues and litters.
... The initial component of the three components and their decomposition during the pyrolysis stage determine the surface properties and the pore structure of the material. 12 The mycelium of the fungus can directly invade the plant cell cavities, spread rapidly in a three-dimensional space-like manner within the plant, and secrete a variety of enzymes for the decomposition of lignin, hemicellulose, and cellulose. The biomass degraded by microorganisms usually results in a porous structure, and the loose structure facilitates the acquisition of specific porous structures and improves surface properties during the pyrolysis and activation processes in biomass. ...
The high catalytic activity and specificity of enzymes can be used to pretreat biomass. Herein, the resourceful, reproducible, cheap, and crude protein-rich cottonseed meal (CM) is selected as a precursor and the protease in the K2CO3–KHCO3 buffer solution is used as the enzyme degradation substance to pretreat CM. The crude protein content is significantly reduced by the protease degradation, and, meanwhile, it results in a looser and porous structure of CM. What is more, it significantly reduces the amount of activator. In the subsequent carbonization process, the K2CO3–KHCO3 in the buffer solution is also used as an activating agent (the mass ratio of CM to activator is 2:1), and after carbonization, the O, S, and N doped porous carbon is obtained. The optimized PCM-800-4 exhibits high heteroatom contents and a hierarchical porous structure. The specific capacitance of the prepared porous carbon reaches up to 233 F g−1 in 6M KOH even when 10 mg of active material is loaded. In addition, a K2CO3–KHCO3/EG based gel electrolyte is prepared and the fabricated flexible capacitor exhibits an energy density of 15.6 Wh kg−1 and a wide temperature range (−25 to 100 °C). This study presents a simple enzymatic degradation and reduced activator dosage strategy to prepare a cottonseed meal derived carbon material and looks forward to preparing porous carbon using other biomass.
... Guar gum is extremely susceptible to enzymatic attack. The presence of both cellulose-producing and hemicelluloseproducing bacteria can cause polymer degradation [76,77]. Guar gum solutions are very stable in the pH 4.5-10 range, highly viscous, resistant to oils, chemicals, and greases, have excellent water binding capacity, multiple hydroxyl groups for hydrogen bonding creation, and a high ability for chemical treatment and copolymerization [8,78,79]. ...
Biopolymers are gaining increased attention in the industry due to their unique characteristics, including being cost-effective, environmentally friendly, and biodegradable. It is also worth noting that natural polymers can be obtained in significant quantities from various renewable sources, whereas synthetic polymers are derived from non-renewable petroleum resources. Enhanced oil recovery (EOR) using biopolymers such as galactomannan, xanthan, welan gum, acacia gum, carboxy methyl cellulose, and corn starch is a developing trend and is projected to replace synthetic polymers (hydrophobically associated polyacrylamides) in the nearby future. The choice of polymers to be utilized in EOR technologies should be based on their cost and availability in addition to their functional properties. Biopolymers in enhanced oil recovery serve to enhance the mobility ratio by increasing the viscosity of displacing fluid and reducing permeability. Even though biopolymers have a tough structure and long polysaccharide chains that make them suitable for enduring severe reservoir conditions, they are highly susceptible to bacterial destruction. In this comprehensive review, we have illustrated the different techniques used to enhance the performance of biopolymers (xanthan gum, guar gum, and starch) in enhanced oil recovery and create new composites that can overcome the challenges faced by these biopolymers under reservoir conditions. We have found that the most famous and favorable techniques used in this approach are, grafting copolymerization, nanocomposites functionalization, amphiphilic style, and hydrogel formation. The review also discussed some other biopolymers (carboxy methyl cellulose, welan gum, and acacia gum) that can be utilized to improve oil recovery and evaluated how widely they have been applied in this field. In this review, we have addressed several important issues (knowledge gaps) that have not been covered in recent studies. We have also provided recommendations and prospects for the successful future implementation of these composites in the EOR field. In conclusion, we hope that this review will help in better understanding the use of these modified biopolymers for enhanced oil recovery (EOR).
... Selulosa adalah komponen terbesar pada tanaman. Selulosa merupakan unit berulang dari ikatan 1,4 D-glukosa dan membentuk rantai linier yang disatukan dengan ikatan hidrogen untuk menciptakan struktur kristal dan daerah amorf yang memberikan kekakuan pada dinding sel (Rytioja et al., 2014). Mikroorganisme selulolitik berperan penting dalam mendegradasi komponen selulosa pada sampah organik. ...
AbstrakBakteri selulolitik memainkan peranan penting dalam biodegradasi komponen selulosa pada sampah organik. Namun, proses pengomposan umumnya melewati fase termofilik (suhu mencapai 55 °C), sehingga tidak semua bakteri dapat bertahan. Sebanyak delapan isolat bakteri selulolitik telah berhasil diisolasi dari tanah, sampah dapur, dan kotoran sapi. Namun, isolat-isolat tersebut belum diketahui aktivitas selulolitiknya pada suhu tinggi dan kemampuannya dalam mendegradasi biomassa serasah daun. Tujuan penelitian ini adalah mengetahui aktivitas selulolitik isolat bakteri pada suhu tinggi secara kualitatif, mengetahui aktivitas selulolitik isolat bakteri secara kuantitatif, dan mengetahui kemampuan isolat bakteri selulolitik dalam mendegradasi biomassa serasah daun. Penelitian dilakukan dengan tahapan peremajaan isolat, skrining kualitatif aktivitas selulolitik isolat pada suhu ruangan, 45 °C dan 55 °C, skrining kuantitatif aktivitas selulolitik isolat, dan uji degradasi biomassa serasah daun. Sebanyak 6 dari 8 isolat bakteri menunjukkan aktivitas selulolitik pada medium Carboxy Methyl Celullose (CMC) Agar pada suhu 55 °C. Berdasarkan uji aktivitas enzim secara kuantitatif, 3 isolat (KS1, KS4, dan SD5) dengan aktivitas enzim tertinggi terpilih untuk pengujian degradasi serasah daun dan menunjukkan rata-rata aktivitas enzim secara berurutan 0,0074 UI/mL; 0,0080 UI/mL; 0,0159 UI/mL. Ketiga isolat mampu mempercepat proses degradasi serasah daun dan berpotensi sebagai agen pengomposan.AbstractHowever, the composting process generally passes through a thermophilic phase (55 °C), so that not all bacteria can survive. A total of 8 isolates of cellulolytic bacteria isolated from soil, kitchen waste, and cow dung have not yet known their cellulolytic activity at high temperatures and their ability to degrade leaf litter biomass. This study aimed to determine the cellulolytic activity of bacterial isolates at high temperatures qualitatively, to determine the cellulolytic activity of bacterial isolates quantitatively, and to determine the ability of these isolates to degrade leaf litter biomass. The research was carried out by reculture isolates; qualitative screening of isolate cellulolytic activity at room temperature, 45 °C and 55 °C; quantitative screening of isolate cellulolytic activity; and leaf litter biomass degradation test. Six of eight bacterial isolates showed cellulolytic activity on Carboxy Methyl Celullose (CMC) Agar medium at 55 °C. Three isolates (KS1, KS4, and SD5) with the highest enzyme activity were selected for the leaf litter degradation test and showed an average enzyme activity of 0.0074 UI/mL; 0.0080 UI/mL; 0.0159 UI/mL, respectively. The three isolates were able to accelerate the degradation process of leaf litter and have potential as composting agents.
... We propose that photobiont-derived carbon could be acquired by L. pygmaea in a mode analogous to carbon uptake by nonlichenised fungi, whereby disaccharides and polysaccharides are degraded to monosaccharides extracellularly before uptake and assimilation (i.e. Basidiomycetes; Rytioja et al., 2014;Ascomycetes;De Vries et al., 2000) (Fig. 6). Ectomycorrhizal fungi (ECM) lack polysaccharide transporters and hydrolyse plantderived polysaccharides extracellularly before monosaccharides are taken up via monosaccharide transporters (Fajardo L opez et al., 2008;Parrent et al., 2009). ...
Lichens are exemplar symbioses based upon carbon exchange between photobionts and their mycobiont hosts. Historically considered a two‐way relationship, some lichen symbioses have been shown to contain multiple photobiont partners; however, the way in which these photobiont communities react to environmental change is poorly understood.
Lichina pygmaea is a marine cyanolichen that inhabits rocky seashores where it is submerged in seawater during every tidal cycle. Recent work has indicated that L. pygmaea has a complex photobiont community including the cyanobionts Rivularia and Pleurocapsa. We performed rRNA‐based metabarcoding and mRNA metatranscriptomics of the L. pygmaea holobiont at high and low tide to investigate community response to immersion in seawater.
Carbon exchange in L. pygmaea is a dynamic process, influenced by both tidal cycle and the biology of the individual symbiotic components. The mycobiont and two cyanobiont partners exhibit distinct transcriptional responses to seawater hydration.
Sugar‐based compatible solutes produced by Rivularia and Pleurocapsa in response to seawater are a potential source of carbon to the mycobiont. We propose that extracellular processing of photobiont‐derived polysaccharides is a fundamental step in carbon acquisition by L. pygmaea and is analogous to uptake of plant‐derived carbon in ectomycorrhizal symbioses.
... CAZymes, as members of gene families, play a vital role in the genome. Specifically, CAZymes found in mushrooms have the ability to utilize cellulose-and lignin-rich substrates like wood chips and straw to obtain nutrients for their own growth and development [21,22]. Considering the nutritional value of H. rajendrae and its demand for large-scale cultivation, we conducted an investigation on its CAZymes. ...
Hericium rajendrae is an emerging species in the genus Hericium with few members. Despite being highly regarded due to its rarity, knowledge about H. rajendrae remains limited. In this study, we sequenced, de novo assembled, and annotated the complete genome of H. rajendrae NPCB A08, isolated from the Qinling Mountains in Shaanxi, China, using the Illumina NovaSeq and Nanopore PromethION technologies. Comparative genomic analysis revealed similarities and differences among the genomes of H. rajendrae, H. erinaceus, and H. coralloides. Phylogenomic analysis revealed the divergence time of the Hericium genus, while transposon analysis revealed evolutionary characteristics of the genus. Gene family variation reflected the expansion and contraction of orthologous genes among Hericium species. Based on genomic bioinformation, we identified the candidate genes associated with the mating system, carbohydrate-active enzymes, and secondary metabolite biosynthesis. Furthermore, metabolite profiling and comparative gene clusters analysis provided strong evidence for the biosynthetic pathway of erinacines in H. rajendrae. This work provides the genome of H. rajendrae for the first time, and enriches the genomic content of the genus Hericium. These findings also facilitate the application of H. rajendrae in complementary drug research and functional food manufacturing, advancing the field of pharmaceutical and functional food production involving H. rajendrae.
... Generally wood decay fungi are functionally classified by the preferred type of biopolymer that they degrade: white-rot fungi degrade cellulose, hemicellulose, and lignin ( Fig. 1A) and brown-rot fungi degrade cellulose and hemicellulose and leave modified lignin behind (Fig. 1B). Another independent type of rot mainly caused by Ascomycetes is soft rot, during which cellulose and hemicellulose is degraded e a process characterised by tapered, cavernous holes (Rytioja et al., 2014;Huckfeldt, 2015). Wood decay is characterised by a diverse set of carbohydrate active enzymes (CAZymes; www.cazy.org). ...
... Brown-rot fungi have additionally evolved a non-enzymatic, energy-saving mechanisms known as the Fenton Reaction (Fig. 1C). This allows a more efficient utilization of lignocellulose (Eastwood et al., 2011) despite maintaining a reduced set of lignocellulose depolymerizing enzymes compared to white-rot fungi Riley et al., 2014;Rytioja et al., 2014). ...
Microbial biodeterioration of timber and woody material in buildings can cause costly restoration procedures. Here, we focus on Serpula lacrymans (commonly known as dry-rot) the fungus causing the most severe damages to buildings in Europe. Although its morphology, lifestyle, and dispersal have been intensively studied, research on microorganisms sharing the same habitat and interacting with the dry-rot fungus is not as comprehensive. Bacteria have long been known to inhabit dead wood, and several studies have shown their association to fungi. However, their identity, ecology, and putative interactions with co-existing fungi in dead wood remains largely underexplored. The interactions of bacterial and fungi have considerable impact on all partners involved covering the full spectrum between antagonistic and beneficial. Fungi are highly capable of manipulating the microbial community in their surroundings (e.g. via pH manipulation) and bacteria, in turn, can influence fungi by affecting the outcomes of (antagonistic) interactions or preventing fungal feedback inhibition via consumption of breakdown products. Associated bacteria on the other side could play an essential role for the fungus as bacteria can exert significant influence on fungal physiology and behaviour. This minireview summarizes the current knowledge on bacterial-fungal interactions in dead wood with a special focus on dry-rot and proposes possible bacterial-fungal interaction (BFI) mechanisms based on examples from soil or decomposing wood from forests.
... This study highlights the remarkable capability of ssNMR spectroscopy in examining the structural changes occurring in lignocellulosic materials, and the same approach can be applied to investigate biomass degradation by various biological agents such as white/brown-rot fungi, as well as in industrial processes. 81 ...
Structural analysis of macromolecular complexes within their natural cellular environment presents a significant challenge. Recent applications of solid-state NMR (ssNMR) techniques on living fungal cells and intact plant tissues have greatly enhanced our understanding of the structure of extracellular matrices. Here, we selectively highlight the most recent progress in this field. Specifically, we discuss how ssNMR can provide detailed insights into the chemical composition and conformational structure of pectin, and the consequential impact on polysaccharide interactions and cell wall organization. We elaborate on the use of ssNMR data to uncover the arrangement of the lignin-polysaccharide interface and the macrofibrillar structure in native plant stems or during degradation processes. We also comprehend the dynamic structure of fungal cell walls under various morphotypes and stress conditions. Finally, we assess how the combination of NMR with other techniques can enhance our capacity to address unresolved structural questions concerning these complex macromolecular assemblies.
... The major lignocellulosic components, polysaccharides (cellulose and hemicelluloses) and aromatic heteropolymers (lignin), are considered promising resources for sustainable biorefinery industries. To develop efficient and eco-friendly processing methods for converting natural polymers into value-added chemical products, various enzymes involved in the depolymerization and bioconversion of each of the major components have been isolated from bacteria and fungi, and characterized extensively [1][2][3][4] . However, most microorganisms cannot efficiently decompose or degrade lignocellulose, especially lignin, in wood biomass because of its complexity [5][6][7] . ...
White-rot fungi play important roles in the global carbon cycle by efficiently degrading lignin and polysaccharides from lignocellulose. Over the years, extensive efforts have been made to elucidate the mechanisms underlying lignin degradation by white-rot fungi. One of them is a molecular genetics approach, which includes genetic modification to alter wood-degrading abilities or metabolism, with the aim of producing commercially valuable chemicals from unutilized lignocellulosic resources. Molecular genetic studies have been conducted on several species, including Pleurotus ostreatus, Phanerochaete sordida, and Phlebia sp., for which a genetic transformation system has been developed. However, the techniques and methodologies available for these fungi are limited, posing a serious bottleneck. Here, we describe recent studies that have developed powerful and effective techniques and methodologies, removing the restrictions of molecular genetics studies on lignin degradation by white-rot fungi.
