scholarly journals Brown Rot-Type Fungal Decomposition of Sorghum Bagasse: Variable Success and Mechanistic Implications

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Gerald N. Presley ◽  
Bongani K. Ndimba ◽  
Jonathan S. Schilling
Keyword(s):  
Plant Biomass ◽  
Specific Activity ◽  
Biomass Conversion ◽  
Xylanase Activity ◽  
Brown Rot ◽  
Fomitopsis Pinicola ◽  
Postia Placenta ◽  
Brown Rot Fungi ◽  
Protein Levels ◽  
Serpula Lacrymans

Sweet sorghum is a promising crop for a warming, drying African climate, and basic information is lacking on conversion pathways for its lignocellulosic residues (bagasse). Brown rot wood-decomposer fungi use carbohydrate-selective pathways that, when assessed on sorghum, a grass substrate, can yield information relevant to both plant biomass conversion and fungal biology. In testing sorghum decomposition by brown rot fungi (Gloeophyllum trabeum,Serpula lacrymans), we found thatG. trabeumreadily degraded sorghum, removing xylan prior to removing glucan.Serpula lacrymans, conversely, caused little decomposition. Ergosterol (fungal biomarker) and protein levels were similar for both fungi, butS. lacrymansproduced nearly 4x lower polysaccharide-degrading enzyme specific activity on sorghum thanG. trabeum, perhaps a symptom of starvation. Linking this information to genome comparisons including other brown rot fungi known to have a similar issue regarding decomposing grasses(Postia placenta, Fomitopsis pinicola)suggested that a lack of CE 1 feruloyl esterases as well as low xylanase activity inS. lacrymans(3x lower than inG. trabeum) may hinderS. lacrymans,P. placenta,andF. pinicolawhen degrading grass substrates. These results indicate variability in brown rot mechanisms, which may stem from a differing ability to degrade certain lignin-carbohydrate complexes.

scholarly journals Localizing gene regulation reveals a staggered wood decay mechanism for the brown rot fungusPostia placenta

2016 ◽  
Vol 113 (39) ◽  
pp. 10968-10973 ◽  
Author(s):  
Jiwei Zhang ◽  
Gerald N. Presley ◽  
Kenneth E. Hammel ◽  
Jae-San Ryu ◽  
Jon R. Menke ◽  
...  
Keyword(s):  
Cell Walls ◽  
Plant Biomass ◽  
Wood Decay ◽  
Brown Rot ◽  
Glycoside Hydrolases ◽  
Ros Generation ◽  
Rna Seq ◽  
Postia Placenta ◽  
Brown Rot Fungi ◽  
Whole Transcriptome

Wood-degrading brown rot fungi are essential recyclers of plant biomass in forest ecosystems. Their efficient cellulolytic systems, which have potential biotechnological applications, apparently depend on a combination of two mechanisms: lignocellulose oxidation (LOX) by reactive oxygen species (ROS) and polysaccharide hydrolysis by a limited set of glycoside hydrolases (GHs). Given that ROS are strongly oxidizing and nonselective, these two steps are likely segregated. A common hypothesis has been that brown rot fungi use a concentration gradient of chelated metal ions to confine ROS generation inside wood cell walls before enzymes can infiltrate. We examined an alternative: that LOX components involved in ROS production are differentially expressed by brown rot fungi ahead of GH components. We used spatial mapping to resolve a temporal sequence inPostia placenta, sectioning thin wood wafers colonized directionally. Among sections, we measured gene expression by whole-transcriptome shotgun sequencing (RNA-seq) and assayed relevant enzyme activities. We found a marked pattern of LOX up-regulation in a narrow (5-mm, 48-h) zone at the hyphal front, which included many genes likely involved in ROS generation. Up-regulation of GH5 endoglucanases and many other GHs clearly occurred later, behind the hyphal front, with the notable exceptions of two likely expansins and a GH28 pectinase. Our results support a staggered mechanism for brown rot that is controlled by differential expression rather than microenvironmental gradients. This mechanism likely results in an oxidative pretreatment of lignocellulose, possibly facilitated by expansin- and pectinase-assisted cell wall swelling, before cellulases and hemicellulases are deployed for polysaccharide depolymerization.

The effect of CaCl2 on growth rate, wood decay and oxalic acid accumulation in Serpula lacrymans and related brown-rot fungi

Holzforschung ◽  
2006 ◽  
Vol 60 (3) ◽  
pp. 339-345 ◽  
Author(s):  
Anne Christine Steenkjær Hastrup ◽  
Bo Jensen ◽  
Carol Clausen ◽  
Frederick Green III
Keyword(s):  
Growth Rate ◽  
Oxalic Acid ◽  
Wood Decay ◽  
Brown Rot ◽  
Malt Extract ◽  
Dry Rot ◽  
Postia Placenta ◽  
Brown Rot Fungi ◽  
Serpula Lacrymans ◽  
Block Test

AbstractThe dry rot fungus,Serpula lacrymans, is one of the most destructive copper-tolerant fungi causing timber decay in buildings in temperate regions. Calcium and oxalic acid have been shown to play important roles in the mechanism of wood decay. The effect of calcium on growth and decay was evaluated for 12 strains ofS. lacrymansand compared to five brown-rot fungi. This was done by treating copper citrate (CC)-treated Southern yellow pine (SYP) wood with a CaCl2solution and estimating the decay rate and amount of soluble oxalic acid in an ASTM soil block test. Decay byS. lacrymanswas found to be significantly inhibited by treatment with CaCl2in the presence of copper. In addition, calcium showed no effect on two strains ofS. lacrymansand oneSerpula himantioidesstrain in non-copper-treated SYP wood blocks. The growth rate ofS. lacrymanswas not affected on malt extract agar containing CaCl2. In summary, a marked decrease was observed in the decay capacity ofS. lacrymansin pine treated with CC+CaCl2. The amount of soluble oxalic acid was measured in CC-treated blocks and blocks also treated with CaCl2. Of the comparative brown-rot fungi, bothAntrodia vaillantii(TFFH 294) andPostia placenta(Mad 698) displayed notable wood decay despite CaCl2treatment, while the remaining strains were inhibited.

Changes in Swelling and Water Absorption of Wood Degraded by Brown Rot Fungi

2013 ◽  
Vol 778 ◽  
pp. 818-822
Author(s):  
Jiří Frankl
Keyword(s):  
Physical Properties ◽  
Water Absorption ◽  
Brown Rot ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Standard Test ◽  
National Standards ◽  
Brown Rot Fungi ◽  
Experimental Laboratory ◽  
Serpula Lacrymans

This paper presents results of experimental laboratory establishment of changes in physical properties (swelling, water absorption) of timber (spruce, pine, oak) caused by wood-destroying fungi (Serpula lacrymans, Stereum hirsutum). The experiment was carried out using standard test samples (20x20x30 mm) prepared from new timber and subsequently exposed to the wood-destroying fungi under optimal growth conditions for the period of 10 to 30 days. Changes in physical properties were observed in the damaged samples in compliance with CSN 490126 (equivalent to ISO 4859-1982, equivalent to ISO 4860-1982) and CSN 490104 Czech National Standards. The experiment proved changes in the observed properties depending on the wood and fungi species and the duration of the exposure.

Comparative Morphology of Early Stages of Brown-Rot Wood Decay

IAWA Journal ◽  
1993 ◽  
Vol 14 (2) ◽  
pp. 127-138 ◽  
Author(s):  
W. Wayne Wilcox
Keyword(s):  
Wood Decay ◽  
Brown Rot ◽  
Comparative Morphology ◽  
Diagnostic Feature ◽  
Postia Placenta ◽  
Brown Rot Fungi ◽  
Early Stages ◽  
Poria Placenta ◽  
White Fir ◽  
Early Progression

Early stages of decay by two brown-rot fungi in two woods were studied by light and scanning electron microscopy. The earliest diagnostic feature to appear was hyphae in the earlywood lumina. The earliest effect on cell walls was the loss of birefringence in the earlywood; Poria placenta (syn. Postia placenta) caused this loss at the earliest stage of decay observed, in both Douglas-fir and white fir, while Gloeophyllum trabeum caused significant weight loss before loss of birefringence was visible. Attack on the latewood progressed from the earlywood, and was different in pattern among the wood/fungus combinations. Hyphal and bore hole diameter increased throughout the early progression of decay and would be useful in evaluating the stage of decay, if the starting diameter of hyphae could be determined. Separation between cells was not observed until moderate stages of decay and, therefore, was not useful in diagnosing early stages of decay.

scholarly journals The termite fungal cultivar Termitomyces combines diverse enzymes and oxidative reactions for plant biomass conversion

2021 ◽  
Author(s):  
Felix Schalk ◽  
Cene Gostinčar ◽  
Nina B. Kreuzenbeck ◽  
Benjamin H. Conlon ◽  
Elisabeth Sommerwerk ◽  
...  
Keyword(s):  
Plant Biomass ◽  
Biomass Conversion ◽  
Degradation Mechanism ◽  
Oxidative Degradation ◽  
Ligninolytic Enzymes ◽  
Brown Rot ◽  
Dicarboxylic Acids ◽  
Lignocellulose Degradation ◽  
Redox Shuttle ◽  
Phenolic Polymer

AbstractMacrotermitine termites have domesticated fungi in the genus Termitomyces as their primary food source using pre-digested plant biomass. To access the full nutritional value of lignin-enriched plant biomass, the termite-fungus symbiosis requires the depolymerization of this complex phenolic polymer. While most previous work suggests that lignocellulose degradation is accomplished predominantly by the fungal cultivar, our current understanding of the underlying biomolecular mechanisms remains rudimentary. Here, we provide conclusive OMICs and activity-based evidence that Termitomyces partially depolymerizes lignocellulose through the combined actions of high-redox potential oxidizing enzymes (laccases, aryl-alcohol oxidases and a manganese peroxidase), the production of extracellular H2O2 and Fenton-based oxidative degradation, which is catalyzed by a newly described 2-methoxybenzoquinone/hydroquinone redox shuttle system and mediated by secreted chelating dicarboxylic acids. In combination, our approaches reveal a comprehensive depiction of how the efficient biomass degradation mechanism in this ancient insect agricultural symbiosis is accomplished through a combination of white- and brown-rot mechanisms.ImportanceFungus-growing termites have perfected the decomposition of recalcitrant plant biomass to access valuable nutrients by engaging in a tripartite symbiosis with complementary contributions from a fungal mutualist and a co-diversified gut microbiome. This complex symbiotic interplay makes them one of the most successful and important decomposers for carbon cycling in Old World ecosystems. To date, most research has focused on the enzymatic contributions of microbial partners to carbohydrate decomposition. Here we provide genomic, transcriptomic and enzymatic evidence that Termitomyces also employs redox mechanisms, including diverse ligninolytic enzymes and a Fenton-based hydroquinone-catalyzed lignin-degradation mechanism, to break down lignin-rich plant material. Insights into these efficient decomposition mechanisms open new sources of efficient ligninolytic agents applicable for energy generation from renewable sources.

scholarly journals Gene Regulation Shifts Shed Light on Fungal Adaption in Plant Biomass Decomposers

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Jiwei Zhang ◽  
Kevin A. T. Silverstein ◽  
Jesus David Castaño ◽  
Melania Figueroa ◽  
Jonathan S. Schilling
Keyword(s):  
Reactive Oxygen Species ◽  
Gene Regulation ◽  
Plant Biomass ◽  
Reactive Oxygen ◽  
Brown Rot ◽  
Comparative Transcriptomics ◽  
White Rot ◽  
Ecological Niches ◽  
Oxygen Species ◽  
Brown Rot Fungi

ABSTRACT Fungi dominate the recycling of carbon sequestered in woody biomass. This process of organic turnover was first evolved among “white rot” fungi that degrade lignin to access carbohydrates and later evolved multiple times toward more efficient strategies to selectively target carbohydrates—“brown rot.” The brown rot adaption was often explained by mechanisms to deploy reactive oxygen species (ROS) to oxidatively attack wood structures. However, its genetic basis remains unclear, especially in the context of gene contractions of conventional carbohydrate-active enzymes (CAZYs) relative to white rot ancestors. Here, we hypothesized that these apparent gains in brown rot efficiency despite gene losses were due, in part, to upregulation of the retained genes. We applied comparative transcriptomics to multiple species of both rot types grown across a wood wafer to create a gradient of progressive decay and to enable tracking temporal gene expression. Dozens of “decay-stage-dependent” ortho-genes were isolated, narrowing a pool of candidate genes with time-dependent regulation unique to brown rot fungi. A broad comparison of the expression timing of CAZY families indicated a temporal regulatory shift of lignocellulose-oxidizing genes toward early stages in brown rot compared to white rot, enabling the segregation of oxidative treatment ahead of hydrolysis. These key brown rot ROS-generating genes with iron ion binding functions were isolated. Moreover, transcription energy was shifted to be invested on the retained GHs in brown rot fungi to strengthen carbohydrate conversion. Collectively, these results support the hypothesis that gene regulation shifts played a pivotal role in brown rot adaptation. IMPORTANCE Fungi dominate the turnover of wood, Earth’s largest pool of aboveground terrestrial carbon. Fungi first evolved this capacity by degrading lignin to access and hydrolyze embedded carbohydrates (white rot). Multiple lineages, however, adapted faster reactive oxygen species (ROS) pretreatments to loosen lignocellulose and selectively extract sugars (brown rot). This brown rot “shortcut” often coincided with losses (>60%) of conventional lignocellulolytic genes, implying that ROS adaptations supplanted conventional pathways. We used comparative transcriptomics to further pursue brown rot adaptations, which illuminated the clear temporal expression shift of ROS genes, as well as the shift toward synthesizing more GHs in brown rot relative to white rot. These imply that gene regulatory shifts, not simply ROS innovations, were key to brown rot fungal evolution. These results not only reveal an important biological shift among these unique fungi, but they may also illuminate a trait that restricts brown rot fungi to certain ecological niches.

High-performance liquid chromatographic analysis of soluble and total oxalate in Ca- and Mg-amended liquid cultures of three wood decay fungi

Holzforschung ◽  
2004 ◽  
Vol 58 (6) ◽  
pp. 682-687 ◽  
Author(s):  
Jonathan S. Schilling ◽  
Jody Jellison
Keyword(s):  
High Performance ◽  
Wood Decay ◽  
Brown Rot ◽  
High Performance Liquid Chromatographic ◽  
White Rot ◽  
Fomitopsis Pinicola ◽  
Decay Fungi ◽  
Postia Placenta ◽  
Medium Components ◽  
Wood Decay Fungi

AbstractTwo brown-rot wood decay fungi,Fomitopsis pinicolaandMeruliporia incrassata, and the white-rot speciesPhanerochaete chrysosporiumwere grown for 4 weeks in liquid culture at 0.35, 0.70, 1.05, and 5.00 mM calcium (Ca) and 1.35 and 2.70 mM magnesium (Mg) concentrations. Soluble and total oxalate levels were quantified using a revised ion-exchange HPLC protocol developed specifically for resolving oxalate and other organic acid anions from medium components. Total oxalate concentrations in brown-rot filtrate were not significantly different among treatments; however, soluble oxalate decreased significantly with increasing Ca concentration. Higher Mg concentrations increased soluble oxalate levels only slightly. There was a significant decrease in medium pH at 5.00 mM Ca for all species, as well as an apparent increase in decarboxylation activity in brown-rot fungi. Total and soluble oxalate levels in the white-rot cultures were generally below detection for all treatments. The results show a significant influence of Ca on soluble oxalate concentrations not seen previously in the brown-rot speciesPostia placenta.

Durability Evaluation of Wood Based Board Materials against Brown-Rot Fungi Effect

2014 ◽  
Vol 923 ◽  
pp. 3-10
Author(s):  
Jan Vanerek ◽  
Dagmar Palovcikova ◽  
Ester Helanová
Keyword(s):  
Bending Strength ◽  
Brown Rot ◽  
Strength Properties ◽  
Solid Wood ◽  
Timber Species ◽  
Brown Rot Fungi ◽  
Deterioration Process ◽  
Wood Rot Fungi ◽  
Serpula Lacrymans ◽  
The Individual

The aim of the experiment was to determine the durability of wood based board materials against wood-rot fungi (Serpula lacrymans) effect. The particle boards, oriented strands boards and plywood as the testing materials were chosen. The spruce solid wood as the reference testing material was selected due to the fact that is most common timber species in the Central European region. The testing samples were exposed to wood-rot fungi and in the individual time periods the weight loss (declaring the deterioration process) and mechanical properties (static bending strength and tensile strength perpendicular to the plane of the board) was investigated. It was found that the deterioration of board materials in a very small weight decreases (up to 1.0%) leads to a significant decrease of their strength properties.

scholarly journals Distribution, Characteristics, and Regulatory Potential of Long Noncoding RNAs in Brown-Rot Fungi

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Alessandra Borgognone ◽  
Walter Sanseverino ◽  
Riccardo Aiese Cigliano ◽  
Raúl Castanera
Keyword(s):  
Noncoding Rnas ◽  
Gc Content ◽  
Brown Rot ◽  
Long Noncoding Rnas ◽  
Upstream Gene ◽  
Coniophora Puteana ◽  
Brown Rot Fungi ◽  
Serpula Lacrymans ◽  
Genomic Regions

Long noncoding RNAs have been thoroughly studied in plants, animals, and yeasts, where they play important roles as regulators of transcription. Nevertheless, almost nothing is known about their presence and characteristics in filamentous fungi, especially in basidiomycetes. In the present study, we have carried out an exhaustive annotation and characterization of lncRNAs in two lignin degrader basidiomycetes, Coniophora puteana and Serpula lacrymans. We identified 2,712 putative lncRNAs in the former and 2,242 in the latter, mainly originating from intergenic locations of transposon-sparse genomic regions. The lncRNA length, GC content, expression levels, and stability of the secondary structure differ from coding transcripts but are similar in these two species and resemble that of other eukaryotes. Nevertheless, they lack sequence conservation. Also, we found that lncRNAs are transcriptionally regulated in the same proportion as genes when the fungus actively decomposes soil organic matter. Finally, up to 7% of the upstream gene regions of Coniophora puteana and Serpula lacrymans are transcribed and produce lncRNAs. The study of expression trends in these gene-lncRNA pairs uncovered groups with similar and opposite transcriptional profiles which may be the result of cis-transcriptional regulation.

scholarly journals An Acidic Thermostable Recombinant Aspergillus nidulans Endoglucanase Is Active towards Distinct Agriculture Residues

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Eveline Queiroz de Pinho Tavares ◽  
Marciano Regis Rubini ◽  
Thiago Machado Mello-de-Sousa ◽  
Gilvan Caetano Duarte ◽  
Fabrícia Paula de Faria ◽  
...  
Keyword(s):  
Aspergillus Nidulans ◽  
Biochemical Characterization ◽  
Plant Biomass ◽  
Specific Activity ◽  
Biomass Conversion ◽  
Hydrolytic Activity ◽  
Lignocellulosic Residues ◽  
Agriculture Residues ◽  
35 Kda Protein

Aspergillus nidulans is poorly exploited as a source of enzymes for lignocellulosic residues degradation for biotechnological purposes. This work describes the A. nidulans Endoglucanase A heterologous expression in Pichia pastoris, the purification and biochemical characterization of the recombinant enzyme. Active recombinant endoglucanase A (rEG A) was efficiently secreted as a 35 kDa protein which was purified through a two-step chromatography procedure. The highest enzyme activity was detected at 50°C/pH 4. rEG A retained 100% of activity when incubated at 45 and 55°C for 72 h. Purified rEG A kinetic parameters towards CMC were determined as Km=27.5±4.33 mg/mL, Vmax=1.185±0.11 mmol/min, and 55.8 IU (international units)/mg specific activity. Recombinant P. pastoris supernatant presented hydrolytic activity towards lignocellulosic residues such as banana stalk, sugarcane bagasse, soybean residues, and corn straw. These data indicate that rEG A is suitable for plant biomass conversion into products of commercial importance, such as second-generation fuel ethanol.

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