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Fast solubilization of recalcitrant cellulosic biomass by the basidiomycete fungus Laetisaria arvalis involves successive secretion of oxidative and hydrolytic enzymes.

Navarro D, Rosso MN, Haon M, Olivé C, Bonnin E, Lesage-Meessen L, Chevret D, Coutinho PM, Henrissat B, Berrin JG - Biotechnol Biofuels (2014)

Bottom Line: The present study illustrates the adaptation of a litter-rot fungus to the rapid breakdown of recalcitrant plant biomass.The cellulolytic capabilities of this basidiomycete fungus result from the rapid, selective and successive secretion of oxidative and hydrolytic enzymes.These enzymes expressed at critical times during biomass degradation may inspire the design of improved enzyme cocktails for the conversion of plant cell wall resources into fermentable sugars.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR1163 Biotechnologie des Champignons Filamenteux, 13288 Marseille, France ; Aix-Marseille Université, Polytech Marseille, UMR1163 Biotechnologie des Champignons Filamenteux, 13288 Marseille, France ; CIRM-CF, UMR1163 Biotechnologie des Champignons Filamenteux, 13288 Marseille, France.

ABSTRACT

Background: Enzymatic breakdown of lignocellulosic biomass is a known bottleneck for the production of high-value molecules and biofuels from renewable sources. Filamentous fungi are the predominant natural source of enzymes acting on lignocellulose. We describe the extraordinary cellulose-deconstructing capacity of the basidiomycete Laetisaria arvalis, a soil-inhabiting fungus.

Results: The L. arvalis strain displayed the capacity to grow on wheat straw as the sole carbon source and to fully digest cellulose filter paper. The cellulolytic activity exhibited in the secretomes of L. arvalis was up to 7.5 times higher than that of a reference Trichoderma reesei industrial strain, resulting in a significant improvement of the glucose release from steam-exploded wheat straw. Global transcriptome and secretome analyses revealed that L. arvalis produces a unique repertoire of carbohydrate-active enzymes in the fungal taxa, including a complete set of enzymes acting on cellulose. Temporal analyses of secretomes indicated that the unusual degradation efficiency of L. arvalis relies on its early response to the carbon source, and on the finely tuned sequential secretion of several lytic polysaccharide monooxygenases and hydrolytic enzymes targeting cellulose.

Conclusions: The present study illustrates the adaptation of a litter-rot fungus to the rapid breakdown of recalcitrant plant biomass. The cellulolytic capabilities of this basidiomycete fungus result from the rapid, selective and successive secretion of oxidative and hydrolytic enzymes. These enzymes expressed at critical times during biomass degradation may inspire the design of improved enzyme cocktails for the conversion of plant cell wall resources into fermentable sugars.

No MeSH data available.


Related in: MedlinePlus

Comparison ofLaetisaria arvalisCAZymes to other fungi. The CAZyme sets identified in the genomes of selected fungi and the transcriptome of L. arvalis CIRM-BRFM514 were compared using double hierarchical clustering. Top tree: fungal genomes analyzed : Lae_ar, Laetisaria arvalis; Lac_bi, Laccaria bicolor; Glo_tr, Gloeophyllum trabeum; Fom_pi, Fomitopsis pinicola; Wol_co, Wolfiporia cocos; Ser_la, Serpula lacrymans; Con_pu, Coniophora puteana; Aga_bi, Agaricus bisporus var. burnettii; Het_an, Heterobasidion annosum; Pun_st, Punctularia strigosozonata; Pyc_ci, Pycnoporus cinnabarinus; Cer_su, Ceriporiopsis subvermispora; Pha_ch, Phanerochaete chrysosporium; Tra_ve, Trametes versicolor; Bje_ad, Bjerkandera adusta; Cop_ci, Coprinopsis cinerea. Right tree: enzyme families represented by their class (GH, GT, PL, CE, CBM and AA) and family number according to the carbohydrate-active enzyme database. The double hierarchical clustering was performed using the Gingko Multivariate Analysis System [15]. Known substrates of CAZy families (most common forms in brackets) are indicated to the left: CW, cell wall; ESR, energy storage and recovery; FCW, fungal cell wall; PCW, plant cell wall; PG, protein glycosylation; U, undetermined; a-1,3-gluc, α-1,3-glucans; a-man, α-mannans; b-1,3-gluc, β-1,3-glucan; cell, cellulose; chit, chitin/chitosan; hemi, hemicelluloses; lign, lignin; pect, pectin.
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Fig3: Comparison ofLaetisaria arvalisCAZymes to other fungi. The CAZyme sets identified in the genomes of selected fungi and the transcriptome of L. arvalis CIRM-BRFM514 were compared using double hierarchical clustering. Top tree: fungal genomes analyzed : Lae_ar, Laetisaria arvalis; Lac_bi, Laccaria bicolor; Glo_tr, Gloeophyllum trabeum; Fom_pi, Fomitopsis pinicola; Wol_co, Wolfiporia cocos; Ser_la, Serpula lacrymans; Con_pu, Coniophora puteana; Aga_bi, Agaricus bisporus var. burnettii; Het_an, Heterobasidion annosum; Pun_st, Punctularia strigosozonata; Pyc_ci, Pycnoporus cinnabarinus; Cer_su, Ceriporiopsis subvermispora; Pha_ch, Phanerochaete chrysosporium; Tra_ve, Trametes versicolor; Bje_ad, Bjerkandera adusta; Cop_ci, Coprinopsis cinerea. Right tree: enzyme families represented by their class (GH, GT, PL, CE, CBM and AA) and family number according to the carbohydrate-active enzyme database. The double hierarchical clustering was performed using the Gingko Multivariate Analysis System [15]. Known substrates of CAZy families (most common forms in brackets) are indicated to the left: CW, cell wall; ESR, energy storage and recovery; FCW, fungal cell wall; PCW, plant cell wall; PG, protein glycosylation; U, undetermined; a-1,3-gluc, α-1,3-glucans; a-man, α-mannans; b-1,3-gluc, β-1,3-glucan; cell, cellulose; chit, chitin/chitosan; hemi, hemicelluloses; lign, lignin; pect, pectin.

Mentions: The 15,679 assembled contigs were assigned to carbohydrate-active enzyme (CAZyme) families listed in the CAZy database [14]. Overall, the assembled transcriptome yielded a total of 266 CAZymes. Because the number of glycosyltransferases (GTs) is comparable among fungi, the completeness of the L. arvalis global transcriptome was evaluated by comparing the number of GTs to that found in sequenced basidiomycete genomes. L. arvalis displayed a number of GTs similar to that encoded by the genomes of other fungi (Additional file 1: Figure S4), suggesting that the global transcriptome successfully captured most CAZyme-encoded genes. The composition and richness of each CAZyme family revealed a complete set of CAZymes covering most of the families, with a total of 149 glycoside hydrolases (GHs), 15 polysaccharide lyases (PLs), 22 carbohydrate esterases (CEs), 32 auxiliary activity enzymes (AAs) and 48 carbohydrate-binding modules (CBMs). The uniqueness of L. arvalis was revealed when comparing its CAZyme repertoire with taxonomically related fungi (Figure 3). L. arvalis displayed a large set of enzymes from families GH7 and AA9, with five and 16 members, respectively. This was completed by a significant set of other predicted cellulose-degrading enzymes from (sub)families GH5_5, GH6, GH45, GH74 and GH131. Among the 20 proteins carrying CBM1 modules, which increase the concentration of the enzymes at the surface of crystalline cellulose, 12 were linked to cellulose-degrading enzymes from (sub)families AA9, GH5_5, GH6, GH7 and GH131. Compared to other basidiomycete fungi, the transcriptome of L. arvalis also suggests a high potential for pectin, mannan and lignin breakdown (Figure 3), all of which are weak in T. reesei.Figure 3


Fast solubilization of recalcitrant cellulosic biomass by the basidiomycete fungus Laetisaria arvalis involves successive secretion of oxidative and hydrolytic enzymes.

Navarro D, Rosso MN, Haon M, Olivé C, Bonnin E, Lesage-Meessen L, Chevret D, Coutinho PM, Henrissat B, Berrin JG - Biotechnol Biofuels (2014)

Comparison ofLaetisaria arvalisCAZymes to other fungi. The CAZyme sets identified in the genomes of selected fungi and the transcriptome of L. arvalis CIRM-BRFM514 were compared using double hierarchical clustering. Top tree: fungal genomes analyzed : Lae_ar, Laetisaria arvalis; Lac_bi, Laccaria bicolor; Glo_tr, Gloeophyllum trabeum; Fom_pi, Fomitopsis pinicola; Wol_co, Wolfiporia cocos; Ser_la, Serpula lacrymans; Con_pu, Coniophora puteana; Aga_bi, Agaricus bisporus var. burnettii; Het_an, Heterobasidion annosum; Pun_st, Punctularia strigosozonata; Pyc_ci, Pycnoporus cinnabarinus; Cer_su, Ceriporiopsis subvermispora; Pha_ch, Phanerochaete chrysosporium; Tra_ve, Trametes versicolor; Bje_ad, Bjerkandera adusta; Cop_ci, Coprinopsis cinerea. Right tree: enzyme families represented by their class (GH, GT, PL, CE, CBM and AA) and family number according to the carbohydrate-active enzyme database. The double hierarchical clustering was performed using the Gingko Multivariate Analysis System [15]. Known substrates of CAZy families (most common forms in brackets) are indicated to the left: CW, cell wall; ESR, energy storage and recovery; FCW, fungal cell wall; PCW, plant cell wall; PG, protein glycosylation; U, undetermined; a-1,3-gluc, α-1,3-glucans; a-man, α-mannans; b-1,3-gluc, β-1,3-glucan; cell, cellulose; chit, chitin/chitosan; hemi, hemicelluloses; lign, lignin; pect, pectin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4197297&req=5

Fig3: Comparison ofLaetisaria arvalisCAZymes to other fungi. The CAZyme sets identified in the genomes of selected fungi and the transcriptome of L. arvalis CIRM-BRFM514 were compared using double hierarchical clustering. Top tree: fungal genomes analyzed : Lae_ar, Laetisaria arvalis; Lac_bi, Laccaria bicolor; Glo_tr, Gloeophyllum trabeum; Fom_pi, Fomitopsis pinicola; Wol_co, Wolfiporia cocos; Ser_la, Serpula lacrymans; Con_pu, Coniophora puteana; Aga_bi, Agaricus bisporus var. burnettii; Het_an, Heterobasidion annosum; Pun_st, Punctularia strigosozonata; Pyc_ci, Pycnoporus cinnabarinus; Cer_su, Ceriporiopsis subvermispora; Pha_ch, Phanerochaete chrysosporium; Tra_ve, Trametes versicolor; Bje_ad, Bjerkandera adusta; Cop_ci, Coprinopsis cinerea. Right tree: enzyme families represented by their class (GH, GT, PL, CE, CBM and AA) and family number according to the carbohydrate-active enzyme database. The double hierarchical clustering was performed using the Gingko Multivariate Analysis System [15]. Known substrates of CAZy families (most common forms in brackets) are indicated to the left: CW, cell wall; ESR, energy storage and recovery; FCW, fungal cell wall; PCW, plant cell wall; PG, protein glycosylation; U, undetermined; a-1,3-gluc, α-1,3-glucans; a-man, α-mannans; b-1,3-gluc, β-1,3-glucan; cell, cellulose; chit, chitin/chitosan; hemi, hemicelluloses; lign, lignin; pect, pectin.
Mentions: The 15,679 assembled contigs were assigned to carbohydrate-active enzyme (CAZyme) families listed in the CAZy database [14]. Overall, the assembled transcriptome yielded a total of 266 CAZymes. Because the number of glycosyltransferases (GTs) is comparable among fungi, the completeness of the L. arvalis global transcriptome was evaluated by comparing the number of GTs to that found in sequenced basidiomycete genomes. L. arvalis displayed a number of GTs similar to that encoded by the genomes of other fungi (Additional file 1: Figure S4), suggesting that the global transcriptome successfully captured most CAZyme-encoded genes. The composition and richness of each CAZyme family revealed a complete set of CAZymes covering most of the families, with a total of 149 glycoside hydrolases (GHs), 15 polysaccharide lyases (PLs), 22 carbohydrate esterases (CEs), 32 auxiliary activity enzymes (AAs) and 48 carbohydrate-binding modules (CBMs). The uniqueness of L. arvalis was revealed when comparing its CAZyme repertoire with taxonomically related fungi (Figure 3). L. arvalis displayed a large set of enzymes from families GH7 and AA9, with five and 16 members, respectively. This was completed by a significant set of other predicted cellulose-degrading enzymes from (sub)families GH5_5, GH6, GH45, GH74 and GH131. Among the 20 proteins carrying CBM1 modules, which increase the concentration of the enzymes at the surface of crystalline cellulose, 12 were linked to cellulose-degrading enzymes from (sub)families AA9, GH5_5, GH6, GH7 and GH131. Compared to other basidiomycete fungi, the transcriptome of L. arvalis also suggests a high potential for pectin, mannan and lignin breakdown (Figure 3), all of which are weak in T. reesei.Figure 3

Bottom Line: The present study illustrates the adaptation of a litter-rot fungus to the rapid breakdown of recalcitrant plant biomass.The cellulolytic capabilities of this basidiomycete fungus result from the rapid, selective and successive secretion of oxidative and hydrolytic enzymes.These enzymes expressed at critical times during biomass degradation may inspire the design of improved enzyme cocktails for the conversion of plant cell wall resources into fermentable sugars.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR1163 Biotechnologie des Champignons Filamenteux, 13288 Marseille, France ; Aix-Marseille Université, Polytech Marseille, UMR1163 Biotechnologie des Champignons Filamenteux, 13288 Marseille, France ; CIRM-CF, UMR1163 Biotechnologie des Champignons Filamenteux, 13288 Marseille, France.

ABSTRACT

Background: Enzymatic breakdown of lignocellulosic biomass is a known bottleneck for the production of high-value molecules and biofuels from renewable sources. Filamentous fungi are the predominant natural source of enzymes acting on lignocellulose. We describe the extraordinary cellulose-deconstructing capacity of the basidiomycete Laetisaria arvalis, a soil-inhabiting fungus.

Results: The L. arvalis strain displayed the capacity to grow on wheat straw as the sole carbon source and to fully digest cellulose filter paper. The cellulolytic activity exhibited in the secretomes of L. arvalis was up to 7.5 times higher than that of a reference Trichoderma reesei industrial strain, resulting in a significant improvement of the glucose release from steam-exploded wheat straw. Global transcriptome and secretome analyses revealed that L. arvalis produces a unique repertoire of carbohydrate-active enzymes in the fungal taxa, including a complete set of enzymes acting on cellulose. Temporal analyses of secretomes indicated that the unusual degradation efficiency of L. arvalis relies on its early response to the carbon source, and on the finely tuned sequential secretion of several lytic polysaccharide monooxygenases and hydrolytic enzymes targeting cellulose.

Conclusions: The present study illustrates the adaptation of a litter-rot fungus to the rapid breakdown of recalcitrant plant biomass. The cellulolytic capabilities of this basidiomycete fungus result from the rapid, selective and successive secretion of oxidative and hydrolytic enzymes. These enzymes expressed at critical times during biomass degradation may inspire the design of improved enzyme cocktails for the conversion of plant cell wall resources into fermentable sugars.

No MeSH data available.


Related in: MedlinePlus