The ligninolytic enzymes of white-rot fungi have a broad substrate specificity and have been implicated in the transformation and mineralization of organopollutants with structural similarities to lignin. This review presents evidence for the involvement of these enzymes in white-rot fungal degradation of munitions waste, pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, bleach plant effluent, synthetic dyes, synthetic polymers, and wood preservatives. Factors relating to the feasibility of using white-rot fungi in bioremediation treatments for organopollutants are discussed.

Feasibility of bioremediation by white-rot fungi.

Biological pretreatment of lignocellulosic biomass--An overview.

https://www.fpl.fs.fed.us/documnts/pdf1986/kirk86a.pdf?origin=publication_detail

Production of multiple ligninases by Phanerochaete chrysosporium: effect of selected growth conditions and use of a mutant strain

https://mmbr.asm.org/content/mmbr/57/3/605.full.pdf

Molecular biology of the lignin-degrading basidiomycete Phanerochaete chrysosporium.

Lignocelluloses are the building blocks of allplants and are ubiquitous to most regions ofour planet. Their chemical properties make it asubstrate of enormous biotechnological value.The basic chemistry of cellulose,hemicellulose, and lignin has a profound effecton lignocellulose tertiary architecture. Theseintricate associations constitute physical andchemical barriers to lignocellulose utilizationand biodegradation in natural and man-madeenvironments. Overcoming these barriers is thekey to unlocking the commercial potential oflignocellulose. Understanding lignocellulosedegradation under natural conditions forms thebasis of any lignocellulose-based application.A variety of microorganisms and mechanisms areinvolved in the complete biodegradation oflignocellulose in natural environments rangingfrom soil and rumen ecosystems to the termitehindgut. The primary objective oflignocellulose pretreatment by the variousindustries is to access the potential of thecellulose and hemicellulose encrusted by ligninwithin the lignocellulose matrix. Currentworking technologies based on the principles ofsolid-state fermentation (SSF) are brieflyreviewed. The use of unsterile lignocellulosicsfor bioremediation purposes holds promise forcost-effective environmental clean-upendeavors. Novel lignocellulose-basedapplications have found functionality intextile, biological control, and medicalresearch fields and might be exploited there inthe near future. Ultimately, lignocellulosewill probably accompany man to his voyages intospace for interest in this field isintensifying. Therefore, proper management oflignocellulose biodegradation and utilizationcan serve to improve the quality of theenvironment, further man's understanding of theuniverse, and ultimately change local economiesand communities.

/pdf/lignocellulose-biodegradation-fundamentals-and-applications-29s7g4vla2.pdf

Lignocellulose biodegradation: Fundamentals and applications

A lignin-degrading enzyme has been detected in culture supernatants of Phanerochaete chrysosporium strain INA-12 grown under non-limiting nitrogen conditions. Highest levels of enzyme activity were observed when glycerol served as carbon source. Veratryl alcohol, a known secondary metabolite of P. chrysosporium, was also produced in high nitrogen/glycerol cultures of strain INA-12 and closely followed the development of the ‘ligninase’ activity. Evolution of 14CO2 from 14C-ring-DHP was readily observed when a hydrogen peroxide-generating system was added to 5-day-old high nitrogen/glycerol cultures which contained high amounts of enzyme.

Ligninolytic enzyme production by Phanerochaete chrysosporium under conditions of nitrogen sufficiency

Lignin biodegradation, carbon loss and in vitro dry matter digestibility (IVDMD) have been investigated during the solid state fermentation of wheat straw by eight previously selected strains of white-rot fungi. A mathematical model of the degradation kinetics is presented. [The time period required to reach maximum rates of 14CO2 and unlabeled CO2 release from (14C)-lignin-labelled wheat straw and from whole wheat straw, respectively, was generally short (6–10 days).] High rates of 14C-lignin degradation were achieved by Pycnoporus cinnabarinus (2.9% 14CO2 evolved/day), an unidentified strain Nancon (3.0%/day), Sporotrichum pulverulentum Nov. (3.4%/day), Bjerkandera adusta (2.4%/day), and Dichomitus squalens (2.3%). However, only the latter two strains degraded whole wheat straw slowly and Bjerkandera adusta was not able to degrade more than 23% of the 14C-lignin. 
Cyathus stercoreus and Dichomitus squalens facilitated the highest improvement in IVDMD (68% against 38% for the sound straw) after 20 and 15 days of cultivation respectively, with low dry matter losses (15–20%). A study of the fate of 14C-lignin during fermentation using these two fungal strains showed that maximal levels of (14C)-water-soluble compounds are reached before peak levels of 14CO2 evolution suggesting that these compounds are intermediates in lignin degradation. A possible relationship between water-soluble lignins and IVDMD improvement is discussed.

Solid-state fermentation, lignin degradation and resulting digestibility of wheat straw fermented by selected white-rot fungi

Structural changes and resulting in-vitro dry matter digestibility (IVDMD) were determined during the course of solid-state fermentation of wheat straw using the lignin-degrading white-rot fungi Sporotrichum pulverulentum, Pycnoporus cinnabarinus and Cyathus stercoreus. The first fungus grew very rapidly on straw but degraded hemicelluloses and cellulose non-selectively resulting in very low IVDMD increases (50% after 35% weight loss). P. cinnabarinus and C. stercoreus preferentially degraded hemicelluloses achieving high improvements in IVDMD (maximum increase of 63 and 94%, respectively) with limited dry weight losses (12 and 18% after 7 and 13 days, respectively). The three fungi exhibited some selectivity among the individual hemicellulose components: O-acetyls were removed essentially at the same rate as xylan, while uronic acids accumulated as incubation proceeded. Conversely, the arabinose content decreased rapidly, especially with C. stercoreus and P. cinnabarinus, suggesting that removal of this pentose was partly responsible for digestibility improvement. Esterified phenolic acids were rapidly degraded during the first stages of decay by all three fungi although P. cinnabarinus and C. stercoreus degraded ferulic acid faster than p-coumaric acid. Lignin was preferentially degraded compared to polysaccharides by all three fungi. The amount of lignin removed, as determined by Klason, correlated well with IVDMD improvement (r=−0.97), while acid detergent lignin (ADL) showed a lower correlation (r=-0.86). Acidolysis yields of decayed lignin pointed to preferential degradation of β-O-4 ether linked units by the fungi. Syringyl units were removed faster than guaiacyl units only after 5 to 10% weight loss was obtained.

Structural changes in wheat straw components during decay by lignin‐degrading white‐rot fungi in relation to improvement of digestibility for ruminants

Disappearance of cell wall components of untreated straw and straw treated with the ligninolytic white-rot fungi Phanerochaete chrysosporium, Dichomitus squalens and Cyathus stercoreus were determined during the course of rumen digestion of samples in nylon bags. The first fungus degraded hemicelluloses and cellulose non-selectively, adversely affecting the digestion rate of crude cell walls. Dichomitus squalens and C. stercoreus preferentially degraded hemicelluloses and lignin, affording cell wall degradation rates 1.5 times higher than in native straw. Furthermore, the extent of cell wall digestion was also significantly enhanced. Both strains improved the extent of cellulose digestion, whereas the potentially degradable xylan fraction remained unchanged. Polysaccharide digestion rates were influenced in different ways depending on the strain tested: straw degraded by C. stercoreus showed an increase in cellulose digestion rate by 50%, whereas residual arabinose units were slowly degraded. Xylan was degraded 1.8 times faster in straw decayed' by D. squalens, while cellulose digestion remained unchanged. Phanerochaete chrysosporium depressed both xylan and cellulose digestion rates. Fungal-treated lignins were solubilised in the rumen faster than in untreated straw, whereas only treatment by C. stercoreus resulted in higher lignin losses. Esterified phenolic acids were extensively degraded by all three fungi. Residual ferulic and p-coumaric acids accumulated during rumen digestion, although only the former decreased in the original straw.

Fungal pretreatment of wheat straw: effects on the biodegradability of cell walls, structural polysaccharides, lignin and phenolic acids by rumen microorganisms

74 Basidiomycetes have been tested for ligninolytic capability on (14C)lignin-labelled wheat straw. Fifteen strains were selected and rested more accurately for ligninolytic activity and the capacity to degrade wheat straw. The asymptote, inflexion point and degradation rate were determined using a model approach. The fungi exhibited very different responses with respect to lignin biodegradation: high asymptote for Pleurotus ostreatus (77%), low inflexion points for Sporotrichum pulverulentum Nov. (6.1 days) and Pycnoporus spp. (2.7 to 4.7 days) with high and slow degradation rates, respectively (0.91% and 0.45% of 14CO2 release/day). Degradation values for (14C)whole-labelled wheat straw exhibited less variation. Finally, the strains Pleurotus ostreatus, Dichomitus squalens and Bjerkandera adusta showed the highest selectivity of lignin removal.

Etienne Odier

Papers

Ligninolytic enzyme production by Phanerochaete chrysosporium under conditions of nitrogen sufficiency

Solid-state fermentation, lignin degradation and resulting digestibility of wheat straw fermented by selected white-rot fungi

Structural changes in wheat straw components during decay by lignin‐degrading white‐rot fungi in relation to improvement of digestibility for ruminants

Fungal pretreatment of wheat straw: effects on the biodegradability of cell walls, structural polysaccharides, lignin and phenolic acids by rumen microorganisms

Screening of white-rot fungi on (14C)lignin-labelled and (14C)whole-labelled wheat straw