title: Morphological and enzymatic response of the thermotolerant fungus Fomes sp. EUM1 in solid state fermentation under thermal stress.
abstract: Thermotolerance of the fungus Fomes sp. EUM1 was evaluated in solid state fermentation (SSF). This thermotolerant strain improved both hyphal invasiveness (38%) and length (17%) in adverse thermal conditions exceeding 30°C and to a maximum of 40°C. In contrast, hyphal branching decreased by 46% at 45°C. The production of cellulases over corn stover increased 1.6-fold in 30°C culture conditions, xylanases increased 2.8-fold at 40°C, while laccase production improved 2.7-fold at 35°C. Maximum production of lignocellulolytic enzymes was obtained at elevated temperatures in shorter fermentation times (8-6 days), although the proteases appeared as a thermal stress response associated with a drop in lignocellulolytic activities. Novel and multiple isoenzymes of xylanase (four bands) and cellulase (six bands) were secreted in the range of 20-150 kDa during growth in adverse temperature conditions. However, only a single laccase isoenzyme (46 kDa) was detected. This is the first report describing the advantages of a thermotolerant white-rot fungus in SSF. These results have important implications for large-scale SSF, where effects of metabolic heat are detrimental to growth and enzyme production, which are severely affected by the formation of high temperature gradients.
authors.affiliation: Centro Nacional de Referencia de Control Biológico, Km.1.5 Carretera Tecomán-Estación FFCC, C.P. 28110, Tecomán, Colima, México.
authors.forename: Armando
authors.initials: A
authors.lastname: Ordaz-Hernández
authors.affiliation: Universidad Politécnica de Tlaxcala, Av. Universidad Politécnica No.1, C.P. 90180, Tepeyanco 90180, Tlaxcala, México.
authors.forename: Eric
authors.initials: E
authors.lastname: Ortega-Sánchez
authors.affiliation: Centro Nacional de Referencia de Control Biológico, Km.1.5 Carretera Tecomán-Estación FFCC, C.P. 28110, Tecomán, Colima, México.
authors.forename: Roberto
authors.initials: R
authors.lastname: Montesinos-Matías
authors.affiliation: Universidad Politécnica de Tlaxcala, Av. Universidad Politécnica No.1, C.P. 90180, Tepeyanco 90180, Tlaxcala, México CONACYT Research Fellow-Instituto Tecnológico Superior de Tierra Blanca. Av. Veracruz S/N Esq. Héroes de Puebla, C.P. 95180, Tierra Blanca, Veracruz, Mexico.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Hernández-Martínez
authors.affiliation: Universidad Tecnológica de Tecámac, Carretera Federal México-Pachuca Km 37.5, C.P. 55740, Tecámac 55740, Estado de México.
authors.forename: Daniel
authors.initials: D
authors.lastname: Torres-Martínez
authors.affiliation: Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco No. 186, C.P. 09340, Del. Iztapalapa, 09340 D.F., México loera@xanum.uam.mx.
authors.forename: Octavio
authors.initials: O
authors.lastname: Loera
mesh_terms: D000220:Adaptation, Biological; D002480:Cellulase / Q000096:biosynthesis / Q000378:metabolism; D044602:Cellulases / Q000096:biosynthesis / Q000378:metabolism; D055453:Coriolaceae / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D043364:Endo-1,4-beta Xylanases / Q000096:biosynthesis / Q000378:metabolism; D005285:Fermentation; D018869:Heat-Shock Response; D006358:Hot Temperature; D025301:Hyphae / Q000502:physiology; D007527:Isoenzymes; D042845:Laccase / Q000096:biosynthesis / Q000378:metabolism; D008031:Lignin / Q000378:metabolism; D003313:Zea mays / Q000378:metabolism
chemical_list: D003470:Culture Media; D007527:Isoenzymes; C036909:lignocellulose; D008031:Lignin; D042845:Laccase; D044602:Cellulases; D002480:Cellulase; D043364:Endo-1,4-beta Xylanases
keywords: lignocellulolytic enzymes; solid state fermentation; thermotolerance; white-rot fungi