Myceliophthora thermophila M77 utilizes hydrolytic and oxidative mechanisms to deconstruct biomass.
Biomass is abundant, renewable and useful for biofuel production as well as chemical priming for plastics and composites. Deconstruction of biomass by enzymes is perceived as recalcitrant while an inclusive breakdown mechanism remains to be discovered. Fungi such as Myceliophthora thermophila M77 appear to decompose natural biomass sources quite well. This work reports on this fungus fermentation property while producing cellulolytic enzymes using natural biomass substrates. Little hydrolytic activity was detected, insufficient to explain the large amount of biomass depleted in the process. Furthermore, this work makes a comprehensive account of extracellular proteins and describes how secretomes redirect their qualitative protein content based on the nature and chemistry of the nutritional source. Fungus grown on purified cellulose or on natural biomass produced secretomes constituted by: cellobiohydrolases, cellobiose dehydrogenase, β-1,3 glucanase, β-glucosidases, aldose epimerase, glyoxal oxidase, GH74 xyloglucanase, galactosidase, aldolactonase and polysaccharide monooxygenases. Fungus grown on a mixture of purified hemicellulose fractions (xylans, arabinans and arabinoxylans) produced many enzymes, some of which are listed here: xylosidase, mixed β-1,3(4) glucanase, β-1,3 glucanases, β-glucosidases, β-mannosidase, β-glucosidases, galactosidase, chitinases, polysaccharide lyase, endo β-1,6 galactanase and aldose epimerase. Secretomes produced on natural biomass displayed a comprehensive set of enzymes involved in hydrolysis and oxidation of cellulose, hemicellulose-pectin and lignin. The participation of oxidation reactions coupled to lignin decomposition in the breakdown of natural biomass may explain the discrepancy observed for cellulose decomposition in relation to natural biomass fermentation experiments.
Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil.|Laboratório Nacional de Ciência e Tecnologia do Bioetanol, Rua Giuseppe Máximo Scolfaro, 10.000, Bairro Guará, Campinas, SP, CEP 13083-970, Brazil.|Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, 74078, USA.
Hévila Brognaro
HB
Dos Santos
Laboratório de Enzimologia, Instituto de Química, UNESP, Araraquara, São Paulo, Brazil.|Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, 74078, USA.
Thaís Milena Souza
TMS
Bezerra
Laboratório Nacional de Ciência e Tecnologia do Bioetanol, Rua Giuseppe Máximo Scolfaro, 10.000, Bairro Guará, Campinas, SP, CEP 13083-970, Brazil.
José G C
JGC
Pradella
Laboratório Nacional de Ciência e Tecnologia do Bioetanol, Rua Giuseppe Máximo Scolfaro, 10.000, Bairro Guará, Campinas, SP, CEP 13083-970, Brazil.
Priscila
P
Delabona
Laboratório Nacional de Ciência e Tecnologia do Bioetanol, Rua Giuseppe Máximo Scolfaro, 10.000, Bairro Guará, Campinas, SP, CEP 13083-970, Brazil.
Deise
D
Lima
Laboratório de Microbiologia e Bioquímica Aplicada, Departamento de Biologia, IBILCE/UNESP, Rua Cristovão Colombo, 2265 Bairro Jd. Nazareth, São José do Rio Preto, SP, CEP 15054-000, Brazil.
Eleni
E
Gomes
Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, 74078, USA.
Steve D
SD
Hartson
Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, 74078, USA.
Janet
J
Rogers
Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, 74078, USA.
Brian
B
Couger
Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, 74078, USA. prade@okstate.edu.
Rolf
http://orcid.org/0000-0002-8154-9286
R
Prade
Biomass; Cellulose degradation; Cellulose hydrolysis; Cellulose oxidation; Myceliophthora thermophila; Secretome composition