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Lignocellulose represents the most abundant source of carbon in the Earth. Thus, fraction technology of the biomass turns up as an emerging technology for the development of biorefineries. Saccharification and fermentation processes require the formulation of enzymatic cocktails or the development of microorganisms (naturally or genetically modified) with the appropriate toolbox to produce a cost- effective fermentation technology. Therefore, the search for microorganisms capable of developing effective cellulose hydrolysis represents one of the main challenges in this era. Schizophyllum commune is an edible agarical with a great capability to secrete a myriad of hydrolytic enzymes such as xylanases and endoglucanases that are expressed in a high range of substrates. In addition, a large number of protein- coding genes for glycoside hydrolases, oxidoreductases like laccases (Lacs; EC 1.10.3.2), as well as some sequences encoding for lytic polysaccharide monooxygenases (LPMOs) and expansins- like proteins demonstrate the potential of this fungus to be applied in different biotechnological process. In this review, we focus on the enzymatic toolbox of S. commune at the genetic, transcriptomic, and proteomic level, as well as the requirements to be employed for fermentable sugars production in biorefineries. At the end the trend of its use in patent registration is also reviewed. KEYWORDS biorefinery, biotechnology, lignocellulolytic enzymes, lignocellulose, Schizophyllum commune

Lignocellulose represents the most abundant source of carbon in the Earth. Thus, fraction technology of the biomass turns up as an emerging technology for the development of biorefineries. Saccharification and fermentation processes require the formulation of enzymatic cocktails or the development of microorganisms (naturally or genetically modified) with the appropriate toolbox to produce a cost- effective fermentation technology. Therefore, the search for microorganisms capable of developing effective cellulose hydrolysis represents one of the main challenges in this era. Schizophyllum commune is an edible agarical with a great capability to secrete a myriad of hydrolytic enzymes such as xylanases and endoglucanases that are expressed in a high range of substrates. In addition, a large number of protein- coding genes for glycoside hydrolases, oxidoreductases like laccases (Lacs; EC 1.10.3.2), as well as some sequences encoding for lytic polysaccharide monooxygenases (LPMOs) and expansins- like proteins demonstrate the potential of this fungus to be applied in different biotechnological process. In this review, we focus on the enzymatic toolbox of S. commune at the genetic, transcriptomic, and proteomic level, as well as the requirements to be employed for fermentable sugars production in biorefineries. At the end the trend of its use in patent registration is also reviewed. KEYWORDS biorefinery, biotechnology, lignocellulolytic enzymes, lignocellulose, Schizophyllum commune

Extreme habitats have usually been regarded as a source of microorganisms that possess robust proteins that help enable them to survive in such harsh conditions. The deep sea can be considered an extreme habitat due to low temperatures (<5ÊC) and high pressure, however marine sponges survive in these habitats. While bacteria derived from deep-sea marine sponges have been studied, much less information is available on fungal biodiversity associated with these sponges. Following screening of fourteen fungi isolated from the deep-sea sponge Stelletta normani sampled at a depth of 751 metres, three halotolerant strains (TS2, TS11 and TS12) were identified which displayed high CMCase and xylanase activities. Molecular based taxonomic approaches identified these strains as Cadophora sp. TS2, Emericellopsis sp. TS11 and Pseudogymnoascus sp. TS 12. These three fungi displayed psychrotolerance and halotolerant growth on CMC and xylan as sole carbón sources, with optimal growth rates at 20ÊC. They produced CMCase and xylanase activities, which displayed optimal temperature and pH values of between 50±70ÊC and pH 5±8 respectively, together with good thermostability and halotolerance. In solid-state fermentations TS2, TS11 and TS12 produced CMCases, xylanases and peroxidase/phenol oxidases when grown on corn stover and wheat straw. This is the first time that CMCase, xylanase and peroxidase/phenol oxidase activities have been reported in these three fungal genera isolated from a marine sponge. Given the biochemical characteristics of these ligninolytic enzymes it is likely that they may prove useful in future biomass conversion strategies involving lignocellulosic materials.

Extreme habitats have usually been regarded as a source of microorganisms that possess robust proteins that help enable them to survive in such harsh conditions. The deep sea can be considered an extreme habitat due to low temperatures (<5˚C) and high pressure, however marine sponges survive in these habitats. While bacteria derived from deep-sea marine sponges have been studied, much less information is available on fungal biodiversity associated with these sponges. Following screening of fourteen fungi isolated from the deep-sea sponge Stelletta normani sampled at a depth of 751 metres, three halotolerant strains (TS2, TS11 and TS12) were identified which displayed high CMCase and xylanase activities. Molecular based taxonomic approaches identified these strains as Cadophora sp. TS2, Emericellopsis sp. TS11 and Pseudogymnoascus sp. TS 12. These three fungi displayed psychrotolerance and halotolerant growth on CMC and xylan as sole carbon sources, with optimal growth rates at 20˚C. They produced CMCase and xylanase activities, which displayed optimal temperature and pH values of between 50–70˚C and pH 5–8 respectively, together with good thermostability and halotolerance. In solid-state fermentations TS2, TS11 and TS12 produced CMCases, xylanases and peroxidase/phenol oxidases when grown on corn stover and wheat straw. This is the first time that CMCase, xylanase and peroxidase/phenol oxidase activities have been reported in these three fungal genera isolated from a marine sponge. Given the biochemical characteristics of these ligninolytic enzymes it is likely that they may prove useful in future biomass conversion strategies involving lignocellulosic materials.

Extreme habitats have usually been regarded as a source of microorganisms that possess robust proteins that help enable them to survive in such harsh conditions. The deep sea can be considered an extreme habitat due to low temperatures (<5ÊC) and high pressure, however marine sponges survive in these habitats. While bacteria derived from deep-sea marine sponges have been studied, much less information is available on fungal biodiversity associated with these sponges. Following screening of fourteen fungi isolated from the deep-sea sponge Stelletta normani sampled at a depth of 751 metres, three halotolerant strains (TS2, TS11 and TS12) were identified which displayed high CMCase and xylanase activities. Molecular based taxonomic approaches identified these strains as Cadophora sp. TS2, Emericellopsis sp. TS11 and Pseudogymnoascus sp. TS 12. These three fungi displayed psychrotolerance and halotolerant growth on CMC and xylan as sole carbón sources, with optimal growth rates at 20ÊC. They produced CMCase and xylanase activities, which displayed optimal temperature and pH values of between 50±70ÊC and pH 5±8 respectively, together with good thermostability and halotolerance. In solid-state fermentations TS2, TS11 and TS12 produced CMCases, xylanases and peroxidase/phenol oxidases when grown on corn stover and wheat straw. This is the first time that CMCase, xylanase and peroxidase/phenol oxidase activities have been reported in these three fungal genera isolated from a marine sponge. Given the biochemical characteristics of these ligninolytic enzymes it is likely that they may prove useful in future biomass conversion strategies involving lignocellulosic materials.

Extreme habitats have usually been regarded as a source of microorganisms that possess robust proteins that help enable them to survive in such harsh conditions. The deep sea can be considered an extreme habitat due to low temperatures (<5˚C) and high pressure, however marine sponges survive in these habitats. While bacteria derived from deep-sea marine sponges have been studied, much less information is available on fungal biodiversity associated with these sponges. Following screening of fourteen fungi isolated from the deep-sea sponge Stelletta normani sampled at a depth of 751 metres, three halotolerant strains (TS2, TS11 and TS12) were identified which displayed high CMCase and xylanase activities. Molecular based taxonomic approaches identified these strains as Cadophora sp. TS2, Emericellopsis sp. TS11 and Pseudogymnoascus sp. TS 12. These three fungi displayed psychrotolerance and halotolerant growth on CMC and xylan as sole carbon sources, with optimal growth rates at 20˚C. They produced CMCase and xylanase activities, which displayed optimal temperature and pH values of between 50–70˚C and pH 5–8 respectively, together with good thermostability and halotolerance. In solid-state fermentations TS2, TS11 and TS12 produced CMCases, xylanases and peroxidase/phenol oxidases when grown on corn stover and wheat straw. This is the first time that CMCase, xylanase and peroxidase/phenol oxidase activities have been reported in these three fungal genera isolated from a marine sponge. Given the biochemical characteristics of these ligninolytic enzymes it is likely that they may prove useful in future biomass conversion strategies involving lignocellulosic materials.

A novel expansin protein (ScExlx1) was found, cloned and expressed from the Basidiomycete fungus Schizophylum commune. This protein showed the canonical features of plant expansins. ScExlx1 showed the ability to form “bubbles” in cotton fibers, reduce the size of avicel particles and enhance reducing sugar liberation from cotton fibers pretreated with the protein and then treated with cellulases. ScExlx1 was able to bind cellulose, birchwood xylan and chitin and this property was not affected by different sodium chloride concentrations. A novel property of ScExlx1 is its capacity to enhance reducing sugars (N-acetyl glucosamine) liberation from pretreated chitin and further added with chitinase, which has not been reported for any expansin or expansin-like protein. To the best of our knowledge, this is the first report of a bona fide fungal expansin found in a basidiomycete and we could express the bioactive protein in Pichia pastoris.

A novel expansin protein (ScExlx1) was found, cloned and expressed from the Basidiomycete fungus Schizophylum commune. This protein showed the canonical features of plant expansins. ScExlx1 showed the ability to form “bubbles” in cotton fibers, reduce the size of avicel particles and enhance reducing sugar liberation from cotton fibers pretreated with the protein and then treated with cellulases. ScExlx1 was able to bind cellulose, birchwood xylan and chitin and this property was not affected by different sodium chloride concentrations. A novel property of ScExlx1 is its capacity to enhance reducing sugars (N-acetyl glucosamine) liberation from pretreated chitin and further added with chitinase, which has not been reported for any expansin or expansin-like protein. To the best of our knowledge, this is the first report of a bona fide fungal expansin found in a basidiomycete and we could express the bioactive protein in Pichia pastoris.