Enhancement and modeling of enzymatic hydrolysis on cellulose from Agave bagasse hydrothermally pretreated in a horizontal bioreactor

One of the major challenges in biofuels production from lignocellulosic biomass is the generation of high glucose titers from cellulose in the enzymatic hydrolysis stage of pretreated biomass to guarantee a cost-effective process. Therefore, the enzymatic saccharification on cellulose at high solid loading is an alternative. In this work, the agave bagasse was hydrothermally pretreated and optimized at 194°C/30min, obtaining a pretreated solid rich in cellulose content (>46.46%), and subjected to enzymatic hydrolysis at high solid levels. A horizontal bioreactor was designed for enzyme saccharification at high solid loadings [25% (w/v)]. The bioreactor improved mixing efficiency, with cellulose conversions up to 98% (195.6g/L at 72h). Moreover, mathematical modeling of cellulase deactivation demonstrated that cellulases lose most of their initial activity in the first hours of the reaction. Also, cellulose was characterized by X-ray diffraction, and the pretreated solids were visualized using scanning electron microscopy.This project was funded by the Secretary of Public Education of Mexico - Mexican Science and Technology Council (SEP-CONACYT) with the Basic Science Project-2015-01 (Ref. 254808). Marcela Sofía Pino also thanks the National Council for Science and Technology (CONACYT, Mexico) for her Master Fellowship support (grant number: 611312/452636), and Dr. Michele Michelin thanks the Portuguese Foundation for Science and Technology (FCT) for her postdoctoral fellowship (SFRH/BPD/100786/2014).info:eu-repo/semantics/publishedVersio

Enzymatic hydrolysis of hidrothermally pretreated agave bagasse

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Fungal growth on coffee husks and spent ground under solidstatecultivation conditions

The processing of coffee generates significant amounts of agricultural wastes. Coffee husks, comprised of dry outer skin, pulp and parchment, are probably the major residues from the handling and processing of coffee (1). Coffee spent ground is the main coffee industry residue obtained during the processing of raw coffee powder to prepare instant coffee. Coffee husks and spent ground are generated in more than two millions tons yearly (2), and the major problem encountered by the industries is the disposal of these residues, since they contain some amount of caffeine, polyphenols and tannins, which makes them toxic in nature (3). Filamentous fungi are microorganisms able to growth over complex substrates behind minimal conditions, and play an important role in the generation of natural compounds with high commercial interest. Therefore, the aim of the present work was to evaluate the ability of some fungal strains to growth on coffee husks (basically the parchment skin the hull that surrounds the coffee bean), and spent grounds, as an alternative to add value to these toxic residues. Strains from the genus Aspergillus, Penicillium, Mucor and Neurospora were used. Microbial growth was carried out in Petri plates containing 30% of coffee husks or spent ground and 70% of CzapekDox saline media, pH 5.0. The plates were inoculated with a suspension containing 5´106 spores/g dry residue, and maintained at 28ºC for 5 days. The spore suspension was prepared by scrap down the spores from PDA plates with a sterilized solution of 0.2% Tween 80, and counted in a Neubauer chamber. Cultivations were done in duplicate to each fungal in each different substrate. Radial growth rate (Ur, mm/h) was monitored kinetically measuring colony diameters every 12h. All the evaluated fungal strains showed mycelium presence over both residues. For almost all the strains, the invasion capacity was higher in coffee spent ground than in coffee husks. Highest growth rates were obtained with Neurospora crassa, with values of 0.99 and 0.76 mm/h for spent ground and husks, respectively. It was thus concluded that coffee husks and spent grounds can be successfully used as substrate for fungal strains growth. Among the evaluated strains Neurospora crassa gave the best results and could be thus evaluated in solidstate fermentation processes for the obtainment of compounds with commercial interest from these two agroindustrial residues

Solid-state fermentation: a strategy for biological detoxification of coffee industry residues

Coffee is the second largest traded commodity in the world, after petroleum, and therefore, the coffee industry is responsible for the generation of large amount of residues. Among these residues, coffee silverskin (CS) and spent coffee grounds (SCG) are generated in significant amounts and merit special attention. Despite the large generation, most of these residues are unutilized, being discharged to the environment or burned for elimination, which are not environmentally friendly techniques. The discharge to the environment cause severe contamination and environmental pollution problems due to their toxic nature (presence of polyphenols, caffeine, and tannins), and burning results in the production of carbon dioxide, the green house gas. If the toxic constituents present in these materials could be removed, or, at least degraded to a reasonably low level, it would open new opportunities for the utilization of these residues. Therefore, the development of methods to decrease their toxicity or to utilize them as raw material for the production of value added compounds is of great relevance. Solid-state fermentation (SSF) can be defined as the growth of microorganisms on moistened solid substrate, in which enough moisture is present to maintain microbial growth and metabolism, but there is no free-moving water. In recent years, SSF has received more interest from researchers since several studies have demonstrated that this process may lead to higher yields and productivities or better product characteristics than submerged fermentation systems. Based on the above mentioned aspects, the present study consisted in evaluating the ability of seven different fungal strains from the genus Aspergillus, Mucor, Penicillium, and Neurospora, to grow and release phenolic compounds from CS and SCG under solid-state cultivation conditions, as an alternative for biological detoxification of these residues. The biomass production and content of phenolic compounds released from the substrates were monitored during the cultivations. According to the results, Penicillium purpurogenum, Neurospora crassa and Mucor released the highest amount of phenolic compounds from the materials, contributing thus for their detoxification, since phenolic compounds are closely related to the material toxicity. Biological detoxification of CS and SCG provides environmental benefits for the disposal of these residues, as well as economical benefits for the conversion of them to value added products that can be industrially applied

Potential of agave bagasse feedstock for biorefinery hydrothermal pretreatment

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Production of mexican brown macroalgae fucoidan and fucosidases under an integral green technology bioproceses by the biorefinery concept

Marine ecosystem can be considered a rather exploited source of natural substances with enormous bioactive potential. In Mexico macro-algae study remain forgotten for research and economic purposes besides the high amount of this resource along the west and east coast. For that reason the Bioferinery Group of the Autonomous University of Coahuila, have been studying the biorefinery concept in order to recover high value byproducts of Mexican brown macro-algae including polysaccharides and enzymes to be applied in food, pharmaceutical and energy industry. Brown macroalgae are an important source of fucoidan, alginate and laminarin which comprise a complex group of macromolecules with a wide range of important biological properties such as anticoagulant, antioxidant, antitumoral and antiviral and also as rich source of fermentable sugars for enzymes production. Additionally, specific enzymes able to degrade algae matrix (fucosidases, sulfatases, aliginases, etc) are important tools to establish structural characteristics and biological functions of these polysaccharides. The aims of the present work were the integral study of bioprocess for macroalgae biomass exploitation by the use of green technologies as hydrothermal extraction and solid state fermentation in order to produce polysaccharides and enzymes (fucoidan and fucoidan hydrolytic enzymes). This work comprises the use of the different bioprocess phases in order to produce high value products with lower time and wastes

Fructosyltransferase Sources, Production, and Applications for Prebiotics Production

Fructooligosaccharides (FOS) are considered prebiotic compounds and are found in different vegetables and fruits but at low concentrations. FOS are produced by enzymatic transformation of sucrose using fructosyltransferase (FTase). Development of new production methods and search for FTase with high activity and stability for FOS production Is an actual research topic. In this article is discussed the most recent advances on FTase and its applications. Different microorganisms have been tested under various fermentation systems in order to identify and characterize new genes codifying for FTase. Some of these genes have been isolated from bacteria, fungi, and plants, with a wide range of percentages of identity but retaining the eight highly conserved motifs of the hydrolase family 32 glycoside. Therefore, this article presents an overview of the most recent advances on FTase and its applications

Hot compressed water pretreatment and surfactant effect on enzymatic hydrolysis using agave bagasse

Agave bagasse is a residual biomass in the production of the alcoholic beverage tequila, and therefore, it is a promising raw material in the development of biorefineries using hot compressed water pretreatment (hydrothermal processing). Surfactants application has been frequently reported as an alternative to enhance monomeric sugars production efficiency and as a possibility to reduce the enzyme loading required. Nevertheless, the surfactants action mechanisms in the enzymatic hydrolysis is still not elucidated. In this work, hot compressed water pretreatment was applied on agave bagasse for biomass fractionation at 194 °C in isothermal regime for 30 min, and the effect of non-ionic surfactants (Tween 20, Tween 80, Span 80, and Polyethylene glycol (PEG 400)) was studied as a potential enhancer of enzymatic saccharification of hydrothermally pretreated solids of agave bagasse (AGB). It was found that non-ionic surfactants show an improvement in the conversion yield of cellulose to glucose (100%) and production of glucose (79.76 g/L) at 15 FPU/g glucan, the highest enhancement obtained being 7% regarding the control (no surfactant addition), using PEG 400 as an additive. The use of surfactants allows improving the production of fermentable sugars for the development of second-generation biorefineries.This project was funded by the Secretary of Public Education of Mexico—Mexican Science and Technology Council (SEP-CONACYT) with the Basic Science Project-2015-01 (Ref. 254808). Marcela Sofía Pino also thanks the National Council for Science and Technology (CONACYT, Mexico) for her Master Fellowship support (grant number: 611312/452636).info:eu-repo/semantics/publishedVersio

Sustainable approach of high-pressure agave bagasse pretreatment for ethanol production

ABSTRACT: Agave bagasse is one of the most abundant lignocellulosic residues readily available for valorization. The agave bagasse was pretreated by applying high-pressure CO2–H2O mixture at temperatures ranging from 150 to 190 °C for a residence time varying from 10 to 50 min. Subsequently, solid phase obtained from pretreatment was subject to enzymatic hydrolysis at high solid loadings. Under optimal conditions, the process integrating pretreatment followed by enzymatic hydrolysis yielded 75.8 mol% of the polysaccharides present in the biomass converted into oligo- or monosaccharides, providing 110.5 g/L of reducing sugars. The monosaccharides present in the obtained hydrolysate were successfully fermented into ethanol, demonstrating the feasibility of performing its biological conversion to commercial biofuels or biochemicals. Thereby, the present study has demonstrated the proof of concept of use of more sustainable high-pressure CO2–H2O pretreatment in the context of lignocellulosic residual biomass valorization based on the biochemical sugar platform.info:eu-repo/semantics/publishedVersio