Fungal solid state fermentation on agro-industrial wastes for acid wastewater decolourization in a continuous flow packed-bed bioreactor

This study was aimed at developing a process of solid state fermentation (SSF) with the fungi Pleurotus ostreatus and Trametes versicolor on apple processing residues for wastewater decolorization. Both fungi were able to colonize apple residues without any addition of nutrients, material support or water. P. ostreatus produced the highest levels of laccases (up to 9 U g-1 of dry matter) and xylanases (up to 80 U g-1 of dry matter). A repeated batch decolorization experiment was set up with apple residues colonized by P. ostreatus, achieving 50% decolorization and 100% detoxification after 24 h, and, adding fresh wastewater every 24 h, a constant decolorization of 50% was measured for at least 1 month. A continuous decolorization experiment was set up by a packed-bed reactor based on colonized apple residues achieving a performance of 100 mg dye L-1 day-1 at a retention time of 50

Correlation of Structure, Function and Protein Dynamics in GH7 Cellobiohydrolases from \u3cem\u3eTrichoderma atroviride\u3c/em\u3e, \u3cem\u3eT. reesei\u3c/em\u3e and \u3cem\u3eT. harzianum\u3c/em\u3e

Background: The ascomycete fungus Trichoderma reesei is the predominant source of enzymes for industrial conversion of lignocellulose. Its glycoside hydrolase family 7 cellobiohydrolase (GH7 CBH) TreCel7A constitutes nearly half of the enzyme cocktail by weight and is the major workhorse in the cellulose hydrolysis process. The orthologs from Trichoderma atroviride (TatCel7A) and Trichoderma harzianum (ThaCel7A) show high sequence identity with TreCel7A, ~ 80%, and represent naturally evolved combinations of cellulose-binding tunnel-enclosing loop motifs, which have been suggested to influence intrinsic cellobiohydrolase properties, such as endo-initiation, processivity, and off-rate. Results: The TatCel7A, ThaCel7A, and TreCel7A enzymes were characterized for comparison of function. The catalytic domain of TatCel7A was crystallized, and two structures were determined: without ligand and with thio-cellotriose in the active site. Initial hydrolysis of bacterial cellulose was faster with TatCel7A than either ThaCel7A or TreCel7A. In synergistic saccharification of pretreated corn stover, both TatCel7A and ThaCel7A were more efficient than TreCel7A, although TatCel7A was more sensitive to thermal inactivation. Structural analyses and molecular dynamics (MD) simulations were performed to elucidate important structure/function correlations. Moreover, reverse conservation analysis (RCA) of sequence diversity revealed divergent regions of interest located outside the cellulose-binding tunnel of Trichoderma spp. GH7 CBHs. Conclusions: We hypothesize that the combination of loop motifs is the main determinant for the observed differences in Cel7A activity on cellulosic substrates. Fine-tuning of the loop flexibility appears to be an important evolutionary target in Trichoderma spp., a conclusion supported by the RCA data. Our results indicate that, for industrial use, it would be beneficial to combine loop motifs from TatCel7A with the thermostability features of TreCel7A. Furthermore, one region implicated in thermal unfolding is suggested as a primary target for protein engineering

Malestares entre los géneros en un colegio secundario : Nuevas libertades y nuevas conflictivas

El presente trabajo surge de la realización de talleres en una escuela secundaria en CABA. Incluyó a toda la comunidad educativa (alumnos/as, docentes, tutores, equipo del DOE -direccion de orientacion al estudiante- y familias), durante los meses de agosto a noviembre del año 2018. Dicho dispositivo se elaboró en respuesta al pedido de abordaje de malestares producidos por las situaciones que generaron las denuncias de violencia de género, padecidas por estudiantes mujeres, así como a los efectos de las respuestas autogestivas por parte de las mismas, denominadas “escraches”. Las relaciones entre los géneros han cambiado en los últimos años, generando nuevas libertades y nuevas conflictivas. Dichas transformaciones presentan desafíos diferentes a mujeres y varones. Los movimientos de #Niunamenos y la Campaña por el Aborto Seguro, Legal y Gratuito impactaron la población adolescente. Se observa una puesta de límites e intolerancia de las mujeres adolescentes con respecto a las conductas de los varones. Estos últimos, presentan perplejidad frente a la necesidad de ocupar un nuevo lugar. Los propósitos de esta presentación son compartir la potencia de lo producido (que excede lo posible de ser recuperado al término del dispositivo), participar de la interrogación acerca de las estrategias para acercar los feminismos a los espacios de socialización masculina, a partir del cuestionar la reproducción de privilegios y complicidades, y pensar la especificidad de las problemáticas en términos teóricos-prácticos como técnicos llamados a intervenir en el campo social.Facultad de Psicologí

Biodiversity of Indigenous Saccharomyces Populations from Old Wineries of South-Eastern Sicily (Italy): Preservation and Economic Potential

In recent years, the preservation of biodiversity has become an important issue. Despite much public discussion, however, current practices in the food industry seldom take account of its potential economic importance: on the contrary, the introduction of industrialized agriculture practices over large areas has often resulted in a dramatic reduction in biodiversity

DEVELOPMENT OF NEW BIOCATALYSTS TO IMPROVE PRODUCTION OF SECOND GENERATION BIOETHANOL

Cellulases, hemicellulases (xylanases) and accessory enzymes (e.g.arabinofuranosidases, pectinases, mannanases) are needed for lignocellulose conversion into fermentable sugars for second generation bioethanol production. The high production costs of the above enzymes limit the bioethanol competitiveness,pushing towards the development of new biocatalysts, with improved catalytic properties, and new processes, whith lower costs. In this work, industrial waste based compost and natural habitats were investigated as a source of new (hemi)cellulolytic bacteria and fungi for discovery of new (hemi)cellulases. Tomato processing waste was shown a suitable substrate for the production of a new alpha-L-arabinofuranosidase (PoAbf) by solid state fermentation (SSF) with the basidiomycete Pleurotus ostreatus. Cellulolyitc activities of Bacillus amyloliquefaciens B31C and Streptomyces sp. G12 isolated from industrial waste based compost were characterized. An endoglucanase (CelB31C) from B.amyloliquefaciens B31C was identified, purified and characterized. The enzyme follows a Michaelis-Menten kinetics towards carboxymethyl-cellulose. It shows a retention of 90% of its activity for at least 6 days of incubation at 40 °C and a range of optimal temperatures from 50 to 70 °C. Investigating the enzymes responsible for cellulase activity produced by Streptomyces sp. G12, proteomic analyses led to the identification of three enzymes acting on cellulose. Gene coding for one of them, named CelStrep, was cloned and sequenced. Recombinant expression of CelStrep was carried out in Escherichia coli and the recombinant enzyme (rCelStrep) was characterized. rCelStrep follows a Michaelis-Menten kinetics towards carboxymethyl-cellulose and exhibits a half life of 24 h and 96 h at 60°C and 50°C, respectively and a retention of around 80% of activity after 96 h at 40°C. 93 microorganisms were isolated from 50 samples collected in the Western Ghat region (India, Kerala). Their screening for cellulases and xylanases production led to the selection of 7 xylanolytic and 14 cellulolytic microorganisms, identified by 16S rRNA sequencing as belonging to the species Bacillus, Streptomyces, Lysinobacillus and Paenibacillus. A further screening in liquid medium revealed the strain Lysinobacillus xylanolyticus XR84 able to produce both cellulase and xylanase activities. Due to the interest in thermo-resistant cellulases and to the ability of filamentous fungi to grow on agro-industrial wastes by SSF, 150 thermophilic filamentous fungi isolated from a "maasra" were screened for cellulase activity production at 45°C, leading to the selection of four Aspergillus strains, a Malbranchea strain and a Myceliophthora thermophila strain, all representing a potential reservoir of thermostable enzymes to be further identified and characterized. Proteomic analyses led to the identification of an alpha-L-arabinofuranosidase (PoAbf) responsible for the xylanase activity produced by P.ostreatus SSF on tomato waste. cDNA coding for PoAbf was synthesized and sequenced. Recombinant expression systems were set up in Kluyveromyces lactis and Pichia pastoris, the latter being the best host for enzyme production (180 mg L-1). Recombinant PoAbf (rPoAbf) follows Michaelis-Menten kinetics. It has a durable activity in a broad range of pH, particularly at pH 5 (t1/2= 51 days), which is also its optimal pH. It shows high stability (t1/2= 7 days) at 30°C and 40°C, the latter being its optimal temperature. It was shown to be a versatile enzyme, able to hydrolyze arabinooligosaccharides, arabinan and arabinoxylan. Glycosylation in position S160 positively affects the enzyme stability as demonstrated by site-directed mutagenesis experiments

Potential of fungi as category I Consolidated BioProcessing organisms for cellulosic ethanol production

Consolidated BioProcessing (CBP) can provide an important contribution to reducing ethanol production costs and moving from cellulosic feedstock to fuel ethanol tanks. Several efforts have so far been focused mainly on CBP category II engineering an ethanologen yeast or bacterium to be cellulolytic, but the limited ability of the category II CBP system for producing enzymes for lignocellulose degradation remains a challenge. As an alternative, category I CBP, aimed at engineering a cellulase producer to be ethanologenic, could be pursued, but it is still in its infancy. Some cellulolytic thermophilic bacteria have been described as potential candidates for category I CBP. However, only fungi naturally produce the needed titers of cellulases required for the complete saccharification of pretreated lignocellulose. In this review, potential of cellulolytic fungi as candidates for category I CBP is discussed

Regulation of Cellulase and Hemicellulase Gene Expression in Fungi

Research on regulation of cellulases and hemicellulases gene expression may be very useful for increasing the production of these enzymes in their native producers. Mechanisms of gene regulation of cellulase and hemicellulase expression in filamentous fungi have been studied, mainly in Aspergillus and Trichoderma. The production of these extracellular enzymes is an energy-consuming process, so the enzymes are produced only under conditions in which the fungus needs to use plant polymers as an energy and carbon source. Moreover, production of many of these enzymes is coordinately regulated, and induced in the presence of the substrate polymers. In addition to induction by mono- and oligo-saccharides, genes encoding hydrolytic enzymes involved in plant cell wall deconstruction in filamentous fungi can be repressed during growth in the presence of easily metabolizable carbon sources, such as glucose. Carbon catabolite repression is an important mechanism to repress the production of plant cell wall degrading enzymes during growth on preferred carbon sources. This manuscript reviews the recent advancements in elucidation of molecular mechanisms responsible for regulation of expression of cellulase and hemicellulase genes in fungi