1,720,973 research outputs found
Ligninolytic enzyme production and dye decolorization by Trametes trogii: application of the Plackett–Burman experimental design to evaluate nutritional requirements
Get PDFThe effects of medium components on laccase, manganese peroxidase and glyoxal oxidase production by Trametes trogii (MYA 28-11) have been studied using Plackett–Burman (PB) experimental design. Copper had the highest positive influence on ligninolytic enzyme production. T. trogii extracellular fluids obtained in the medium which rendered the highest ligninolytic production (45.32 U/ml laccase, 214.5 mU/ml manganese peroxidase and 116 mU/ml glyoxal oxidase) also showed the greatest ability to decolorize the dyes Ponceau 2R (a xylidine derivative), malachite green and anthraquinone blue (at rates of 2.14, 1.35 mg and 3 mg dye/(ml h), respectively). The relationship among decolorization rates and ligninolytic enzyme activities was analyzed by multiple regression. The results fit a linear plus interactions model. The comparison of the response surfaces obtained, suggests that while laccase activity has a greater importance in xylidine degradation, manganese peroxidase activity plays the major role in malachite green decolorization.Fil: Levin, Laura Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Forchiassin, Flavia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Viale, A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentin
White-rot fungi, new biotechnological tools for a cleaner environment
Get PDFWhite-rot fungi are key regulators of the global C-cycle; they are so far unique in their ability to complete degrade all components of our principal renewable resource, lignocellulose. These filamentous wood decay fungi, common inhabitants of forest litter and fallen trees, can attack all the wood components, the lignin as well as the polysaccharides. They produce an impressive array of enzymes (cellulases, hemicellulases, pectinases and ligninases) with potential in a wide range of biotechnological applications, including hazardous waste remediation and in the industrial processing of paper and textiles. Interest in these fungi has increased during the past two decades spurred by the ability of these organisms to degrade a wide variety of hazardous compounds (including polychlorinated biphenyls, pesticides, explosives, polycyclic aromatic hydrocarbons and industrial dyes). To be able to use the white rotters in these processes it is necessary to learn how their enzymes are secreted, how they operate and under what conditions they are active. Our current research is focused on these subjects, and in the screening of new isolates for their ability to degrade xenobiotics, in the search of more efficient strains.Fil: Levin, Laura Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Forchiassin, Flavia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin
Stabilization studies of Fomes sclerodermeus laccases
Get PDFStability of laccase isoenzymes from a crude extract obtained from Fomes sclerodermeus grown on wheat bran medium was studied. The variables assessed were temperature, pH and additives. As revealed by PAGE, three bands of laccase, each with different thermal inactivation pattern, were detected in the crude extract: after 6 h at 50 °C and pH 8, Lc2 was the most resistant, while the Lc1 and Lc3 bands were almost completely inactivated. This pattern of inactivation was observed at all temperatures and pH tested. Laccase activity was more stable in the 5-10 pH range when incubated at 40 and 50 °C; at 30 °C and 24 h the enzyme remained fully active in the 3-11 pH range. The effect of additives (veratryl alcohol, trehalose, glycerol, mannitol, glutaraldehyde, CuSO4 and 1-HBT) on laccase stability was tested. The stability was enhanced with CuSO4 (1.25 mM), glycerol (0.2%) and mannitol (1%). The presence of both CuSO4 and glycerol caused a 3-fold increase in the half-life values.Fil: Papinutti, Víctor Leandro. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Dimitriu, Pedro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Forchiassin, Flavia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentin
Removal and degradation of the fungicide dye malachite green from aqueous solution using the system wheat bran–Fomes sclerodermeus
Get PDFThe triphenylmethane dye malachite green (MG), commonly used as fungicide, was adsorbed onto wheat bran (WB) by using a batch technique. The effects of contact time, dye concentration and pH were investigated. The equilibrium was attained after 40 min of contact time irrespective of MG concentration. The pH of MG aqueous solution greatly influenced the adsorption capacity and intensity, it was found that maximum adsorption of dye occurred at pH range 7–9, where the amount of dye removed was nearly 90%. Data obtained on adsorption at different dye concentrations and pH range 4–7 were used to plot the Freundlich isotherms. WB with MG adsorbed at pH range 4–7 was used as substrate for the growth of the white rot fungi Fomes sclerodermeus and Phanerochaete chrysosporium. The presence of MG (nearly 24 mg g−1 dry WB) delayed the fungal growth. MG was completely degraded by F. sclerodermeus cultures at pH 5, in concordance with the highest ligninases production. Thus, pH values not only influenced the adsorption capacity of WB but they were also important for growth, enzyme production and finally, dye degradation. This technique should have broad applications in bioremediation processes of water and wastewater.Fil: Papinutti, Víctor Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Mouso, Nora. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Forchiassin, Flavia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin
Aplicaciones biotecnológicas de los hongos lignocelulolíticos
No full textLos hongos se caracterizan por su forma de nutrición: heterótrofa absortiva. La producción de enzimas extracelulares les permite aprovechar sustratos poliméricos difícilmente degradados por otros organismos. Muchas de estas enzimas se utilizan también en procesos indutriales. La facilidad de cultivo de estos microorganismos y su alta eficiencia de producción los hace particularmente aptos para la obtención de enzimas con fines biotecnológicos. Los hongos lignocelulolíticos son capaces de degradar todos los componentes de las paredes celulares vegetales (pectina, celulosa, hemicelulosa y lignina). Los materiales lignocelulósicos representan un gran reservorio de materia y energía. La biodegradación fúngica es un proceso clave en el ciclo biogeoquímico del carbono, y esta actividad descomponedora es probablemente su más valioso servicio. Sus enzimas además se utilizan en diversas industrias: pectinasas, xilanasas y celulasas para facilitar la extracción de jugos, aromas, aceites y pigmentos en la industria alimentaria. Pectinasas y xilanasas para la obtención de fibras en la industria textil. Ligninasas en biopulpado y xilanasas en bioblanqueado, en la industria celulósico-papelera. Las ligninasas además, por su baja especifidad y fuerte capacidad oxidativa son capaces de degradar una gran variedad de contaminantes orgánicos, entre ellos: hidrocarburos aromáticos policíclicos, bifenilos policlorados, tinturas industriales, etc. Para utilizar a estos hongos y sus enzimas en distintos procesos biotecnológicos, es necesario clarificar los mecanismos enzimáticos empleados, determinar cómo secretan sus enzimas, cómo operan y bajo qué condiciones están activas. El trabajo actual de nuestro laboratorio abarca estas cuestiones, la optimización de procesos de fermentación (sumergidos y en estado sólido) para la obtención de enzimas lignocelulolíticas y el relevamiento de nuevas especies en la búsqueda de organismos más eficientes para utilizarlos en la industria del papel y en la biodegradación de diferentes contaminantes ambientales.Fil: Levin, Laura Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Forchiassin, Flavia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin
Contributions to research on white-rot fungi, lignin-degrading enzymes, and their industrial and environmental applications
No full textWhite-rot fungi (WRF), the most frequent wood-rotting organisms, are so far unique in their ability to completely degrade all components of our principal renewable resource, lignocellulose. They produce an impressive array of enzymes (cellulases, hemicellulases, pectinases and ligninases) with potential in a wide range of biotechnological applications. WRF and their ligninolytic enzymes (such as laccase and Mn-peroxidase) are able to degrade many pollutants. In pulp and paper manufacturing they are applied in biopulping, biobleaching and effluent treatment. Recently, there has been a growing interest in studying the ligninolytic enzymes of a wider array of WRF, with the expectation of finding better lignin-degrading systems for use in various biotechnological applications. To be able to use the white-rotters in these processes it is necessary to learn how their enzymes are secreted, how they operate and under what conditions they are active. Our current research is focused on these subjects and in the screening of new isolates for their ability to degrade xenobiotics, in the search of more efficient strains. Reducing the cost for enzyme production is still needed in order to develop enzymatic treatment processes for different industrial and environmental applications, competitive with other treatment technologies. At present, one of the objectives of our work is reducing this cost by means of process optimization using statistical experimental designs, and the use of cheaper growth substrates such as agricultural and food wastes. We identified new strains of Trametes versicolor, Trametes villosa, Stereum hirsutum and Fomes sclerodermeus which demonstrated an outstanding ability in dye degradation. Trametes trogii BAFC 463 almost completely removed several dyes as well as high priority pollutants such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Pycnoporus sanguineus BAFC 2126 proved to be a potential candidate for use in softwoods biopulping processes. Efficient bleaching of loblolly pine kraft pulp could be achieved in a chlorine-free sequence, with culture supernatants from T. trogii, followed by a peroxide stage under mild conditions. Its high potential purified laccase, was recently applied as biocatalyst for oxygen electro-reduction in biofuel cells. With our results we wish to contribute to expand the knowledge on this important group of fungi and their biotechnological applications.Fil: Levin, Laura Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; ArgentinaFil: Forchiassin, Flavia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Micología y Botánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Micología y Botánica; Argentin
Extracción y caracterización de poligaracturonasa de Fomes sclerodermeus producida por fermentación en estado sólido
Get PDFSe estudió la producción de poligalacturonasa (PG) por Fomes sclerodermeus usando técnicas de fermentación en estado sólido. La actividad PG máxima (26 U/g ps) fue observada entre los días 11 y 13. La actividad PG en los extractos crudos fue más estable a pH 5-6 y 30 °C, con una actividad óptima a pH 5 y a 50 °C. Las condiciones óptimas para la extracción de PG se lograron con una única extracción empleando Na2SO4 como solvente, con 10 minutos de agitación. En el escalado del sistema, la actividad PG por gramo de peso seco de sustrato disminuyó cerca de 60% comparada con la obtenida en frascos Erlenmeyer, pero la actividad total fue mayor.Polygalacturonase (PG) production by Fomes sclerodermeus using solid-state fermentation (SSF) was carried out. Maximal PG activity (26 U/gdw) was obtained between days 11 and 13 at the end of exponential growth. PG activity in the crude extract was more stable at pH 5-6 and 30 °C and had optimum activity at pH 5 and 50 °C. Optimal conditions for PG extraction were: one time extraction with Na2SO4 as solvent with 10 min. of agitation. In a scale-up system, PG activity per gram of dry substrate decreased about 60% compared with the activity obtained in an Erlenmeyer flask; however, high total PG activity was obtained.Fil: Salariato, Diego Leonel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Diorio, Luis Alberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mouso, Nora. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Forchiassin, Flavia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Lignin modifying enzymes in Fomes sclerodermeus
Get PDFWhite rot fungi are the only organisms capable to mineralize the lignin to CO2. These fungi posses at least three enzymes impicated in the process: lignin peroxidase, manganese dependent peroxidase and laccase. The screening of 13 strains of white-rot fungi showed that F. sclerodermeus was the more efficient ligninase producer fungus and the decolorization of the polymeric dye poly R was fast. Lip activity was not detected in any of the media tested. Optimal media conditions for laccase and MnP production in synthetic liquid media were found. The Doehlert uniform factorial experimental design was applied to study the effect of MnSO4, CuSO4 and asparagine. Among the aromatic compounds evaluated in GA medium, vanillin and fenilic acid were the more efficient laccase and MnP inducers. On the other hand, in semidefined medium (YPG) aromatic compounds had not effect on any activity. Under this conditions only copper and Mn increased laccase and MnP activities, respectively. Solid state fermentation on wheat or soy bran, high laccase and MnP were produced. Neither aromatic compounds, MnSO4 nor CuSO4 increased none of the activities. The effect on known ligninolytic inducers was studied on a crystalline cellulose (CC) based medium. Cellulolytic activities decreased 3-fold when CuSO4 or MnSO4 were added to the medium. MnP activity was only detected in the media containing MnSO4 as inducer, while the laccase activity was constitutiver expressed under all the conditions tested, and it was increased to a major extent when copper was added to the medium. Wood blocks of poplar incubated during six months with F. sclerodermeus registered dry weight losses of 51%. Differential hydrolysis of the wood blocks revealed that the remaining content of cellulose and lignin were 58 y 56%, respectively. On the other hand, the hydrosolubles increased 3-fold, due to the degradation products. Observation of the wood showed the degradation of parenchyma rays and thinning of the cell walls. Growing on sawdust medium, enzyme activities were produced only with poplar, whereas on cedar laccase and MnP were inhibited. Laccase and MnP produced in YPG medium by F. sclerodcrmeus were purified to electrophoretic homogeneity and characterized biochemically. Two isoenzymes of laccase (Lac I y Lac II) and two MnP (MnP I y MnP II) were found. Isoforms of both systems showed slight differences in their isoelectric points. Laccase activity produced on wheat bran based medium revealed three bands in PAGE with differential patterns of inactivation. Among the compounds tested, the CuSO4 1,25 mM was the best stabilizer. The combination of both CuSO4 and glycerol 0,2% further increased the stability of the enzyme. Laccase activity produced in the optimized conditions was used in assays of decoloration and detoxification of the fungicide malachite green. P. chrysosporium was used as biotest, this Fungus showed a high sensitivity to the fungicide, while degradation by F. sclerodermeus laccase rendered a not toxic compound. The presence of I-HBT accelerated the detoxification. The detoxification response of other white-rot fungi was similar to that observed for P. chrysosporium.Fil:Papinutti, Víctor Leandro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Estudio e identificación de enzimas extracelulares en Ascobolus gamundii
Get PDFSe estudió la capacidad de Ascobolus gamundii (Pezizales, Ascomicetes) para producir enzimas degradativas extracelulares in "vitro". Luego de analizar el patrón enzimático producido en medios sintéticos líquidos, se concluyó que A. gamundii es un hongo coprófilo productor de enzimas celulolíticas, xilanolíticas y amilolíticas. Los tres complejos enzimáticos estudiados son inducibles por sustrato, y parcialmente inhibidos en presencia de glucosa en el medio de cultivo. Todos presentaron también una inducción específica, así como una inducción generalizada de menor intensidad con otros sustratos complejos no específicos. Los tres sistemas presentan además múltiples formas enzimáticas, isoenzimas. característica de este tipo de enzimas. Todas las enzimas son extracelulares, liberadas al medio después de sintetizarse durante el crecimiento activo y no se quedan adsorbidas a las paredes micelianas. Se determinaron además características bioquímicas de todas las enzimas estudiadas, así como el requerimiento de cationes en el medio de cultivo. El sistema celulolítico está compuesto por las tres enzimas componentes características de este complejo enzimático: actividad endoglucanasa, exoglucanasa y β-glucosidasa. Estos resultados confirman que este hongo es un verdadero agente celulolítico, adaptado al medio en el que vive naturalmente. El sistema celulolítico se induce preferencialmente en presencia de celulosa cristalina como sustrato. Se logró aún mejor inducción al utilizar un medio mixto de celulosa cristalina y xilano, que estaría reflejando en mejor medida las condiciones naturales en que crece A. gamundii. Con lactosa, se indujo el sistema celulolítico pero ésta fuente de carbono no logró promover el crecimiento del hongo. Lacelobiosa no resultó un buen inductor del sistema celulolítico. El sistema xilanolítico está representado mayoritariamente por la actividad endoxilanasa, ya que la actividad β-xilosidasa resultó muy baja, casi nula. Este sistema se indujo preferencialmente con xilano; pero al igual que en el caso del sistema celulolítico, el medio mixto resultó superior. La lactosa tuvo un comportamiento similar al obtenido con el sistema celulolítico. El sistema amilolítico está representado por la actividad α-amilasa y la actividad glucoamilasa. La inducción con almidón obviamente resultó la más favorable para este complejo enzimático, así como el uso de maltosa.The ability of Ascobolus gamundii (Pezizales, Ascomycetes) to produce extracellular degrading enzymes "in vitro" was studied. After analysing the enzymes produced in artificial liquid media. A. gamundii appears to be a true cellulolytic fungus also showing xylanolytic and amylolytic activity. The three enzyme systems studied are truly extracellular. The enzymes in all cases are synthesised during active growth and diffuse out of the mycelium into the liquid media away from the hyphai walls. These enzyme systems can be induced not only by specific substrates, but also in a lower degree by other complex polymers as well. The three are partially inhibited in the presence of glucose (in no case total inhibition is achieved). For each enzymatic activity A. gamundii produces several isozymes, characteristic of these types of enzymes. Biochemical characterisation,of each enzyme as well as the need of several cations in the growth media was also determined. The cellulolytic system of A. gamundii produces its three characteristic enzymes: endoglucanases, exoglucanases and β-glucosidases, confirming its role as a decomposer and its adaptation to its natural habitat: dung. This enzyme system is induced specifically by crystalline cellulose. An even better induction was achieved when using a combined medium of crystalline cellulose and xylan which mirrors better this fungus' natural environment. When lactose was used as an inducer. high specific activity was obtained because growth was not promoted. Cellobiose proved to be a poor inducer for this enzyme system. The xylanolytic system is nearly entirely represented by the endoxylanase activity. β-xylosidase activity was found to be very low in all fractions studied, rendering a limitation for its survival in nature. Good induction was obtained with xylan, but as it happened with the cellulolytic system, the combined medium of crystalline cellulose and xylan proved better induction. With lactose, the results obtained were similar to those for the cellulolytic system. The amylolytic system is represented by the α-amylase and the glucoamylase activity. Induction with starch was the best for this enzyme system, as well as the use of maltose for this purpose.Fil:Sivori, Andrea Silvia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Regulation of the cellulase complex production by Saccoboloides
No full textSe evaluó la capacidad de Saccobolus saccoboloides (Pezizales, Ascomycetes) de producir el sistema celulolítico completo en medio de cultivo líquido sintético. La caracterización de las enzimas producidas permite afirmar que este hongo coprófilo es un verdadero agente celulolítico, ya que su complejo enzimático presenta las tres actividades necesarias para la digestión del polímero (β-1,4 endoglucanasa, β-1,4 exoglucanasa y β-glucosidasa), y que estas enzimas son extracelulares, termoestables y (a diferencia de las de otros organismos) poco inhibidas por producto final. El crecimiento fue alto en glucosa y celobiosa, sin producción de enzimas, en tanto que en celulosa hubo muy buen crecimiento y actividad enzimática, evidenciándose diferencias de respuesta según el medio elegido. La nutrición nitrogenada no afecta la producción enzimática, sino el crecimiento: se investiga, por lo tanto, el control por fuente carbonada, en cultivos de reemplazo. En la inducción, cuando no pudo medirse endoglucanasa, se utilizó un método alternativo de degradación de CMC (Carboximetilcelulosa) en placa (CMCasa). La celulosa fue el mejor inductor, seguida por la lactosa. El sistema no se induce en presencia de glucosa, sorbosa, maltosa ni almidón, y se detecta una mínima actividad en xilano. La CMC es un pobre inductor, en tanto que la celobiosa tiene un efecto diferencial. Cuando se ensayó el efecto represor de los no inductores se ve que el sistema no se reprime fácilmente y que la glucosa y celobiosa tienen efecto diferencial. Finalmente la mezcla de dos inductores tiene un esperado efecto negativo. Las enzimas se producen en todos casos por síntesis de novo, las dos formas diferentes de β-glucosidasa se regulan independientemente, y existe inducción cruzada con el complejo xilanasa. Estos datos, junto al análisis de isoenzimas producidas en cada condición permite postular un novedoso modelo regulatorio que explicaría como los hongos filamentosos son estimulados a producir las hidrolasas específicas para degradar celulosa.The cellulase complex production by Saccobolus saccoboloides (Pezizales, Ascomycetes) was evaluated. This fungus produces a complete cellulase system. The enzyme characterisation shows that S. saccoboloides is a true cellulolytic organism, the three enzymes (β-glucosidase, β-1,4 endoglucanase and β-1,4 exoglucanase) required for the complete cellulose hydrolisis were produced. All the enzymes were thermostable and did not show end-product inhibition. Glucose and cellobiose were good sources for growth but not for enzyme production, cellulose was a suitable carbon source for growth and cellulase production: there was evidence for carbon regulation. The nitrogen source affected biomass production, and therefore enzyme production. For these reasons carbon nutrition was investigated as the primary control of cellulase production. When endoglucanase and exoglucanase could not be measured, an alternative Carboxymethylcellulose-clearing method was used. Crystalline cellulose was the best inducer, followed by lactose. The other mono- di- or polysaccharides were non inducers or poor inducers. Cellobiose or glucose repressed cellulase production in cellulose containing media. This repression was selective for some components of the cellulase complex, and was not observed using repressor concentrations below 3% w/v. Moreover, the degree of repression varied with the age of the cultures. The mixture of both inducers had an unexpected negative effect. Cellulase production by this fungus is inducible and subject to a complex repression by easily metabolized sugars. The enzyme production is due to the novo synthesis, two different β-glucosidase forms were observed and cellulase-xylanase cross-induction was observed as well. The data analysis shows that it is possible to present a new model of cellulase regulation, that would explain cellulose recognition and cellulase induction in filamentous fungi.Fil: Magnelli, Paula E.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
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