Effect of Wood Modification on Lignin Consumption and Synthesis of Lignolytic Enzymes by the Fungus Panus (Lentinus) tigrinus

Lignin consumption and synthesis of lignolytic enzymes by the fungus Panus (Lentinus) tigrinuscultivated on solid phase (modified and unmodified birch and pine sawdusts) were studied. The fungus grew better on and consumed more readily the birch lignin than the pine wood. Peroxidase activity was higher in the case of pine sawdust; laccase and lignolytic activities, in the case of birth sawdust. Treatment with ammonia or sulfuric acid decreased lignin consumption by this fungus cultivated on either medium. Modification of sawdust by ultrasound increased lignin consumption and may be recommended for accelerating biodegradation of lignocellulose substrates.     

The formation and regeneration of mycelial protoplasts in hyper lignolytic fungus,strain IZU-154

Over 2 × 10⁷/ml protoplasts were obtained from mycelia of hyper lignolytic fungus (nomenclatured as strain IZU-154) by treatment with the lytic enzyme NovoZym 234 in the presence of 0.05 M maleic acid buffer (pH 5.6) containing 0.6 M MgSO₄. The protoplasts regenerated at more than 10% of frequency on solid 2% agar medium containing 0.6 M sucrose as an osmotic stabilizer overlaid with 0.5% agar containing the stabilizer. In the determination of the lignolytic activities of 50 regenerants from protoplasts, 2 strains which degraded more than 56% of the lignin during incubation for 30 d and showed activity higher than the parent were found. The regeneration from protoplasts of this fungus was suggested to be useful for the breeding of strains having higher lignolytic activity than this fungus.     

Efficient,environmentally-friendly and specific valorization of lignin: promising role of non-radical lignolytic enzymes

Lignin is the second most abundant bio-resource in nature. It is increasingly important to convert lignin into high value-added chemicals to accelerate the development of the lignocellulose biorefinery. Over the past several decades, physical and chemical methods have been widely explored to degrade lignin and convert it into valuable chemicals. Unfortunately, these developments have lagged because of several difficulties, of which high energy consumption and non-specific cleavage of chemical bonds in lignin remain the greatest challenges. A large number of enzymes have been discovered for lignin degradation and these are classified as radical lignolytic enzymes and non-radical lignolytic enzymes. Radical lignolytic enzymes, including laccases, lignin peroxidases, manganese peroxidases and versatile peroxidases, are radical-based bio-catalysts, which degrade lignins through non-specific cleavage of chemical bonds but can also catalyze the radical-based re-polymerization of lignin fragments. In contrast, non-radical lignolytic enzymes selectively cleave chemical bonds in lignin and lignin model compounds and, thus, show promise for use in the preparation of high value-added chemicals. In this mini-review, recent developments on non-radical lignolytic enzymes are discussed. These include recently discovered non-radical lignolytic enzymes, their metabolic pathways for lignin conversion, their recent application in the lignin biorefinery, and the combination of bio-catalysts with physical/chemical methods for industrial development of the lignin refinery.     

Effect of a lignin-degrading fungus on feeding preferences of Formosan subterranean termite (Isoptera: Rhinotermitidae) for different commercial lumber

The feeding preferences of the Formosan subterranean termite, Coptotermes formosanus Shiraki, for commercial lumber Alaska yellow cedar, Chamaecyparis nootkatensis (D. Don) Spach; yellow birch, Betula alleghaniensis Britton; northern red oak, Quercus rubra L.; redwood, Sequoia sempervirers (D. Don) Endl; and spruce (Picea spp.) were examined to determine whether the presence of the lignin-degrading basidiomycete Marasmiellus troyanus (Murrill) Singer could alter the relative preference of termites for these wood species. In paired choice tests with fungus-inoculated sawdust versus control sawdust, termites showed a strong preference for the fungus-inoculated sawdust for all wood species tested, except for Alaska yellow cedar. In a multiple-choice test using sawdust without fungus, termites showed a very strong preference for red oak sawdust over the other three species. In a paired choice test using fungus-inoculated sawdust, termites showed a preference for redwood over red oak sawdust. In a feeding test using autoclaved wood blocks without fungal decay, there was no difference in termite consumption of birch, red oak, or redwood. The relative preference of termites for redwood increased when blocks were decayed by M. troyanus for 3 and 8 wk. These results indicate that chemical modifications due to fungal decay affected the feeding preference of termites for different commercial lumber.     

粗毛栓菌的形态学变异

白腐担子菌粗毛栓菌是一种木栖真菌,通常根据其子实体的形态学特征对其进行鉴定.在不同条件下培养,该菌将呈现出显著的形态变化:在振荡的营养液中,只能形成空心的菌丝体球;在静止的半丰富和贫营养液体培养基中,将分别产生花簇样和蜂巢样结构;在麦草粉和松木屑上,子实体呈圆面包状;在杨木条上,将长出类似于野生型的平伏状或叠瓦状子实体.本文还提出了真菌形态建成机制的新观点.     

不同碳源条件下广叶绣球菌转录组分析

【背景】广叶绣球菌(Sparassis latifolia)是一种名贵的食用菌,其木质纤维素降解的分子机制尚不明确。【目的】了解广叶绣球菌在不同碳源条件下木质纤维素降解相关基因表达动态。【方法】通过转录组测序技术对分别以葡萄糖、纤维素+木质素、纤维素及松木屑为碳源的广叶绣球菌基因表达谱进行分析。以葡萄糖为碳源的样本为对照,分别对不同碳源下广叶绣球菌显著差异表达的基因进行功能分析。【结果】Geneontology(Go)富集分析表明,以葡萄糖为碳源的样本为对照,差异表达基因主要富集在碳水化合物利用的过程,如多糖催化过程、碳水化合物催化过程、碳水化合物代谢过程及多糖代谢过程等。碳水化合物活性酶(Carbohydrate-activeenzymes,CAZymes)功能注释表明,碳源种类主要影响了半纤维素和纤维素降解相关糖苷水解酶家族基因的表达,其中涉及半纤维素降解的相关酶基因上调幅度最大。同时,在纤维素+木质素、松木屑为碳源的处理组中一些转录因子基因上调表达显著。【结论】不同碳源显著影响了广叶绣球菌基因表达谱,这种对碳源的适应也可能反映了广叶绣球菌攻击植物细胞壁的机制,研究结果为深入了解广叶绣球菌木质纤维素降解的分子机理和相关功能基因提供了一些参考。     

Elevated CO2 does not ameliorate effects of ozone on carbon allocation in Pinus halepensis and Betula pendula in symbiosis with Paxillus involutus

The effect of 700 μmol CO₂ mol⁻¹, 200 nmol ozone mol⁻¹ and a combination of the two on carbon allocation was examined in Pinus halepensis co-cultured with Betula pendula in symbiosis with the ectomycorrhizal fungus Paxillus involutus . The results show that under low nutrient and ozone levels, elevated CO₂ has no effect on the growth of B. pendula or P. halepensis seedlings nor on net carbon partitioning between plant parts. Elevated CO₂ did not enhance the growth of the fungus in symbiosis with the birch. On the other hand, ozone had a strong negative effect on the growth of the birch, which corresponded with the significantly reduced growth rates of the fungus. Exposure to elevated CO₂ did not ameliorate the negative effects of ozone on birch; in contrast, it acted as an additional stress factor. Neither ozone nor CO₂ had significant effects on biomass accumulation in the pine seedlings. Ozone stimulated the spread of mycorrhizal infection from the birch seedlings to neighbouring pines and had no statistically significant effects on phosphoenolpyruvate carboxylase (PEPC) or ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity in the pine needles or on PEPC activity in pine roots.     

Quantification of lignin–carbohydrate linkages with high-resolution NMR spectroscopy

A quantitative approach to characterize lignin–carbohydrate complex (LCC) linkages using a combination of quantitative ¹³C NMR and HSQC 2D NMR techniques has been developed. Crude milled wood lignin (MWLc), LCC extracted from MWLc with acetic acid (LCC-AcOH) and cellulolytic enzyme lignin (CEL) preparations were isolated from loblolly pine (Pinus taeda) and white birch (Betula pendula) woods and characterized using this methodology on a routine 300 MHz NMR spectrometer and on a 950 MHz spectrometer equipped with a cryogenic probe. Structural variations in the pine and birch LCC preparations of different types (MWL, CEL and LCC-AcOH) were elucidated. The use of the high field NMR spectrometer equipped with the cryogenic probe resulted in a remarkable improvement in the resolution of the LCC signals and, therefore, is of primary importance for an accurate quantification of LCC linkages. The preparations investigated showed the presence of different amounts of benzyl ether, γ-ester and phenyl glycoside LCC bonds. Benzyl ester moieties were not detected. Pine LCC-AcOH and birch MWLc preparations were preferable for the analysis of phenyl glycoside and ester LCC linkages in pine and birch, correspondingly, whereas CEL preparations were the best to study benzyl ether LCC structures. The data obtained indicate that pinewood contains higher amounts of benzyl ether LCC linkages, but lower amounts of phenyl glycoside and γ-ester LCC moieties as compared to birch wood.     

Evidence that the fungus cultured by leaf-cutting ants does not metabolize cellulose

Leaf‐cutting ants are a very specialized group of ants that cultivate fungus gardens in their nests, from which they obtain food. The current opinion is that the fungus cultivated by leaf‐cutting ants digests cellulose. Here we reassess the cellulose‐degrading capability of the fungus by using two complementary approaches tested in four Attini species (genera Atta and Acromyrmex): (1) ability of fungus to grow in cellulose; and (2) lignin/cellulose ratio in the refuse material dumped outside the nest, as an indicator of cellulose consumption. We found that (1) the fungus did not grow in cellulose, and (2) the lignin/cellulose ratio was much lower in the ants' refuse than in material digested by cellulose‐digesting organisms, such as brown‐rot fungus, termites, and ruminant mammals. This evidence strongly suggests the inability of the fungus to degrade cellulose. Therefore, the fungus–ant symbiosis and the ecological role of leaf‐cutting ants need to be reconsidered.     

利用农业废弃物固态发酵裂褶菌F17产锰过氧化物酶的基质优化(英文)

锰过氧化物酶(MnP)在环保领域有着广阔的应用前景。目前,利用廉价基质生产MnP,尤其是利用工农业废弃物生产MnP的研究受到了国内外学者的广泛关注。本实验利用响应面方法从几种不同的农业废弃物中筛选裂褶菌F17(Schizophyllum sp.F17)产MnP的固态发酵基质。结果表明,以0.52∶0.15∶0.33的比例组成的松木屑、稻草和黄豆粉的混合基质为发酵产MnP的最佳基质,发酵第6天MnP的活力最高,达到11.18 U/g。因此,利用农业废弃物固态发酵产锰过氧化物酶在减低酶的成本和环境污染物治理方面具有重要的意义。     

Extracellular Oxidases of the Lignin-Degrading Fungus <Emphasis Type="Italic">Panus tigrinus</Emphasis>

Two extracellular oxidases (laccases) were isolated from the extracellular fluid of the fungus Panus (Lentinus) tigrinus cultivated in low-nitrogen medium supplemented with birch sawdust. The enzymes were purified by successive chromatography on columns with TEAE-cellulose and DEAE-Toyopearl 650M. Both oxidases catalyze oxidation of pyrocatechol and ABTS. Moreover, oxidase 1 also catalyzes oxidation of guaiacol, o-phenylenediamine, and syringaldazine. The enzymes have identical pH (7.0) and temperature (60–65°C) optimums. Absorption spectra of the oxidases differ from the spectra of typical “blue” laccases and are similar to the spectrum of yellow oxidase.__________Translated from Biokhimiya, Vol. 70, No. 6, 2005, pp. 850–854.Original Russian Text Copyright © 2005 by Cadimaliev, Revin, Atykyan, Samuilov.     

Investigation of lignin-carbohydrate complexes in kraft pulps by selective enzymatic treatments

The occurrence of covalent bonds between residual lignin and polysaccharides in birch and pine kraft pulps was investigated by specific enzymatic treatments. Pure enzymes degrading cellulose, xylan and mannan were used both separately and in combination. Comparison of the molar masses of polysaccharides and lignin in the orginal pulps and in the residual pulps after enzymatic treatments showed that residual lignin in birch kraft pulp is linked at least to xylan. A minor portion may also be linked to cellulose. In pine kraft pulp some of the residual lignin appears to be linked to cellulose, glucomannan and xylan. The linkages between lignin and cellulose and hemicelluloses may be either native or formed during pulp processing. The results also provided new information on the synergistic action of cellulose- and hemicellulose-degrading enzymes on pulp fibres. The synergism appears to be mainly due to the structure of the pulp fibres, with different layers of cellulose sheets, hemicelluloses and lignin. On the other hand the results also provided information about fibre structure. The degradation of xylan clearly enhanced the action of enzymes on cellulose, suggesting that xylan partially covers the cellulose. A similar phenomenon was not observed in the simultaneous hydrolysis of glucomannan and cellulose. However, the results suggest that glucomannan does interact with cellulose, possibly by non-covalent linkages. Received: 8 July 1998 / Received revision: 7 October 1998 / Accepted: 11 October 1998     

不同栽培基质对肺形侧耳营养成分及呈味物质的影响

以3种林木枝条废弃物（金银花、松木、杨木）作为栽培基质,对4株综合性状较优异的肺形侧耳菌株进行栽培,测定不同栽培基质的肺形侧耳子实体中粗蛋白、水解氨基酸、游离氨基酸、总糖及5′-核苷酸组成与含量,研究不同菌株、不同栽培基质下肺形侧耳子实体营养成分及呈味物质的含量,以柞木+棉籽壳传统栽培基质作为对照。结果表明不同菌株之间、不同栽培基质之间肺形侧耳子实体的营养成分及呈味物质都具显著差异,其中以金银花作为栽培基质时,菌株P2、P3、P45子实体粗蛋白和水解氨基酸含量在4种基质中最高;以松木作为栽培基质时其游离氨基酸总量在4种基质中普遍最高;所有样品中的等鲜浓度值（EUC）范围为67.91-146.13g MSG/100g,其中以金银花为基质的菌株P3子实体EUC值最高,而以柞木+棉籽壳为基质的菌株P7子实体EUC值最低。本研究可为基于各地农林废弃物开展肺形侧耳的栽培生产提供一定的理论指导。     

Mode of coniferous wood decay by the white rot fungus Phanerochaete carnosa as elucidated by FTIR and ToF-SIMS

The softwood degrading white-rot fungus, Phanerochaete carnosa, was investigated for its ability to degrade two coniferous woods: balsam fir and lodgepole pine. P. carnosa grew similarly on these wood species, and like the hardwood-degrading white-rot fungus Ceriporiopsis subvermispora, P. carnosa demonstrated selective degradation of lignin, as observed by Fourier transform infrared spectroscopy and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Lignin degradation across cell walls of decayed pine samples was also evaluated by ToF-SIMS and was shown to be uniform. This study illustrates softwood lignin utilization by a white-rot fungus and reveals the industrial potential of the lignocellulolytic activity elicited by this fungus.     

Modification of wood lignin by the fungus Panus tigrinus

The treatment of sawdust with the fungus Panus tigrinus VKM F-3616 D changed the contents of functional groups in lignin from wood raw material. These changes are accompanied by the release of carboxyl and phenyl hydroxyl groups involved in chemical bond formation between wood particles in pressed materials manufactured from wood wastes.     

裂褶菌F17固态发酵产锰过氧化物酶及其发酵动力学模型的建立

白腐真菌分泌的锰过氧化物酶是木质素降解酶系统的主要组分,对木质素解聚,纸浆和染料的脱色均有重要作用.利用裂褶菌F17在自行设计的通气托盘式反应器中,以松木屑、稻草及黄豆粉为混合营养基质进行固态发酵生产锰过氧化物酶.在自制通气托盘式反应器中,裂褶菌F17能够产生锰过氧化物酶,发酵96 h时,最高酶活力达到13.51 U/...     

Wood-decay type and fungal guild dominance across a North American log transplant experiment

We incubated 196 large-diameter aspen (Populus tremuloides), birch (Betula papyrifera), and pine (Pinus taeda) logs on the FACE Wood Decomposition Experiment encompassing eight climatically-distinct forest sites in the United States. We sampled dead wood from these large-diameter logs after 2 to 6 y of decomposition and determined wood rot type as a continuous variable using the lignin loss/density loss ratio (L/D) and assessed wood-rotting fungal guilds using high-throughput amplicon sequencing (HTAS) of the ITS-2 marker. We found L/D values in line with a white rot dominance in all three tree species, with pine having lower L/D values than aspen and birch. Based on HTAS data, white rot fungi were the most abundant and diverse wood-rotting fungal guild, and soft rot fungi were more abundant and diverse than brown rot fungi in logs with low L/D values. For aspen and birch logs, decay type was related to the wood density at sampling. For the pine logs, decay type was associated with the balance between white and brown/soft rot fungi abundance and OTU richness. Our results demonstrate that decay type is governed by biotic and abiotic factors, which vary by tree species.     

Biodegradation of radiolabelled synthetic lignin (14C-DHP) and mechanical pulp in a compost environment

Mineralization of radioactive synthetic lignin (14C-DHP) was studied in a compost environment at 35, 50 and 58 degrees C. Compost samples were successively extracted with water, dioxane and alkali, and the molecular weight distribution of some extracts was determined by gel permeation chromatography (GPC). Biodegradation of lignin-containing spruce groundwood (SGW) and pine sawdust was concurrently determined in controlled composting tests by measuring evolved CO2. The temperatures were the same as in the 14C-DHP mineralization experiment and bleached kraft paper, with a lignin content of 0.2%, was used as a reference. The mineralization of 14C-DHP was relatively high (23-24%) at 35 degrees C and 50 degrees C, although the mixed population of compost obviously lacks the most effective lignin degraders. At 58 degrees C the mineralization of 14C-DHP, as well as the biodegradation of SGW and sawdust, was very low, indicating that the lignin-degrading organisms of compost were inactivated at this temperature. SGW was poorly biodegradable (<40%) in controlled composting tests compared with kraft paper (77-86%) at all temperatures, which means that lignin inhibits the degradation of carbohydrates. During the incubation, water-soluble degradation products, mainly monomers and dimers, and the original 14C-DHP were either mineralized or bound to humic substances. A substantial fraction of 14C-DHP was incorporated into humin or other insolubles.     

Changes in organic matter composition of forest soil treated with a large amount of urea to promote ammonia fungi and the abilities of these fungi to decompose organic matter

Organic matter composition (lignin, holocellulose, 50% (v/v) methanol extract, water-soluble carbohydrate (WSC) and phenolics (WSP), petroleum ether extract, and ash) of A₀ layer soil treated with 700 g/m² of urea to promote ammonia fungi was investigated in a Japanese red pine (Pinus densiflora) forest. Nine species of fungi were found during the study period of 18 months after the treatment. Of these, seven species belong to the ammonia fungi. WSC content of the treated soil was lower than that of the control. Methanol extract content increased initially after the treatment, then decreased to below the control level. There were no consistent differences in other components between the treated plot and the control. The abilities to decompose cellulose, lignin, chitin, protein and lipid in 18 strains in 10 species of the ammonia fungi were also screened. Cellulose was not lysed byPseudombrophila deerata, Hebeloma spp. andLaccaria bicolor. Strong lignolytic activity was shown byLyophyllum tylicolor, Coprinus echinosporus andP. deerata. Chitin was decomposed byAmblyosporium botrytis, L. tylicolor, C. echinosporus andHebeloma vinosophyllum. All strains possessed proteolytic and lipolytic activities. Supply of glucose to the culture media resulted in weaker enzyme activities except for lignolytic ability.     

Degradation of poplar wood by Fomes sclerodermeus: production of ligninolytic enzymes in sawdust of poplar and cedar

Fomes sclerodermeus is a white-rot fungus. Its production of laccase, manganese peroxidase and lignin peroxidase on sawdust-based media was evaluated. No lignin peroxidase activity was measured in any media tested. The higher production of laccase and manganese peroxidase were found on media containing poplar sawdust. F. sclerodermeus was grown on wood blocks of poplar during six months. Dry weight losses of the blocks reached a mean value of 51%. The quantification of cellulose and lignin in the 6-months incubated blocks showed losses of up to 58 and 56% for cellulose and lignin, respectively. The decay examined under microscope revealed mycelium colonizing the lumen of vessel elements, cell wall thinning and entire degradation of the radial parenchyma.