Extraction and characterization of polygalacturonase of Fomes sclerodermeus produced by solid-state fermentation / Extracción y caracterización de poligaracturonasa de Fomes sclerodermeus producida por fermentación en estado sólido

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.

Se 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.

Degradación de hojas de pino por Stereum hirsutum / [Degradation of pine needles by Stereum hirsutum]

Pine-needle degradation by Stereum hirsutum was studied under conditions of solid state fermentation with the aim of accelerating its decomposition, avoiding the accumulation in situ and in view of the possible utilization of the residual organic matter. Three experimental systems were tested: pine needles alone and with the addition of either a nitrogen source or barley grain. Determinations were made at 14 and 28 days of incubation. All treatments showed substrate degradation. The addition of a nitrogen source raised enzymatic activities measured but not the degree of degradation. Grain addition resulted in higher biomass, enzyme activities, sugar accumulation and degradation of the substrate. Fungal biomass estimated as N-acetyl glucosamine allowed calculation of the actual degradation of the substrate, that reached 19

at 28 d of culture without additions and 44

at 14 d in pine-needles with grain.

Efecto del cocultivo de especies fúngicas sobre la degradación de residuos lignocelulósicos / [Effect of cocultivating fungal species on the degradation of lignocellulose residues]

The degradation potential of Phanerochaete sordida, Trametes trogii, Coprinus truncorum and Paecilomyces sp. upon yard wastes was evaluated. The species had been inoculated individually or in pairs formed by P. sordida and Paecilomyces sp., T. trogii and Paecilomyces sp., and C. truncorum and Paecilomyces sp. The highest level of endoxilanase activity was produced by P. sordida growing alone, during day 21 (1.09 U/g of dry material), but in P. sordida and Paecilomyces sp. cultures, the detected activity did not overcome 0.27 U/g of dry material during the whole experiment. T. trogii showed maximum activity on day 14 (0.78 U/g of dry material), but in T. trogii and Paecilomyces sp. cultures, the values increased until day 21 (1.07 U/g of dry material). P. sordida endocellulase activity reached its maximum on day 28 (0.08 U/g of dry material), but in P. sordida and Paecilomyces sp. cultures, this activity increased during the whole experiment (0.04 U/g of dry material). The major weight loss was found in P. sordida (27.6

). The possible beneficial effect of co-culture in yard wastes biodegradation is discussed.

Degradación de residuos vegetales por Coprinus truncorum usando dos métodos de cultivo / Degradation of plant waste by Coprinus truncorum using 2 culture methods

Degradation of yard wastes by Coprinus truncorum growing in a vertical aereated bioreactor or in flasks was studied. There was a constant decay of reducing sugars in the medium that avoided their accumulation and their possible repression of degradative enzymes. Endoxylanase activity at first showed a similar pattern in both culture conditions, with maximal activity on the 12th day, but flasks maintained a high activity thereafter. Flasks also showed a higher endoglucanase activity with a peak on the 18th day, whereas the maximal value in the bioreactor was reached on the 26th day. No Mn-peroxidase and only low values of laccase activity were found. The measurements of pH and soluble proteins during the incubation period were suitable indicators of the degradation process by C. truncorum.

Interacción entre hongos coprófilos y su efecto en la degradación de su sustrato natural / Interaction between coprophilous fungi and its impact on its natural substrate degradation

Six species of coprophilous fungi were isolated from cow dung. Each species, or a combination of two or more, were inoculated on dung and their capacity of degradation of the substrate was measured as dry weight loss, endoglucanase activity and loss of cellulose. Degradation of CMC agar medium was also established. As a result of their interespecific relationship, a minor degradative capacity was observed when more than one species were cultured except for one combination.

Efecto del Ca2+ y de la luz sobre el desarrollo de Iodophanus carneus / Effect of calcium and light on the development of Iodophanus carneus

Ca2+ affects the mycelial morphological characteristics in I. carneus, modulating the development and conditioning the sexual differentiation. In Ca2+ 0 mM there was an interaction with light and development, in darkness the colonies did not reach the edge of Petri dishes and spiral growth was observed. In darkness the number of hyphae/mm was greater than those grown in light, except in Ca2+ 1 mM, at 28 mm of inoculum, and Ca2+ 2 mM, at 16 and 28 mm, where the number of hyphae/mm was greater. In cords and apothecial number and location a similar behavior was observed, evidencing a direct relation between these, Ca2+ concentration and light.

Evaluación de la capacidad celulolítica de Ascobolus furfuraceus (Fungi, Ascomycotina) / [Evaluation of the cellulolytic capacity of Ascobolus furfuraceus (Fungi, Ascomycotina)]

Growth kinetic variables (dry weight, mycelial protein, extracellular protein and pH evolution) were measured in Ascobolus furfuraceus cultures either with soluble cellulose (CMC) or crystalline cellulose as only carbon sources. When growing on CMC the mycelial protein production reached a maximum at 14 days, while the extracellular protein was maximal at 17 days. On crystalline cellulose more delay was observed (4 and 14 days, respectively). Straight lineal correspondence (r = 0.9883) was observed between the extracellular protein production and enzymatic activity kinetics, showing parallel behavior of these variables. When the biomass and extracellular protein production rates were analysed, the maxima were observed at diverse growth stages. For CMC, the dry weight production rythm precedes the cellulolytic system liberation rythm (maxima at 9 and 14 days, respectively). When crystalline cellulose was the substrate, the maximal rates were inverse, 16th day for biomass production rythm and 12th day for enzyme release rythm. On the basis of such tests and analyses, a model to explain cellulose degration by A. furfuraceus, is proposed.

Desarrollo de Iodophanus carneus ante distintas calidades de luz / [Development of Iodophanus carneus under different types of light]

Development of Iodophanus carneus was conditioned by light. Hyphal growth was photoinhibited. Light wavelength increases carotene contents being blue and near ultraviolet light the most effective. For ascocarp induction or inhibition, the most effective wavelengths were blue. The possible role of flavins is discussed.