Showing papers by "Cristiane S. Farinas published in 2018"

Smart Fertilization Based on Sulfur–Phosphate Composites: Synergy among Materials in a Structure with Multiple Fertilization Roles

Abstract: Sulfur is currently a bottleneck for agronomic productivity Many products are based on the application of elemental sulfur (S°), but the ability of the soil to oxidize them is variable and dependent on the presence of oxidizing microorganisms In this work, a composite was designed based on a matrix of S° prepared by low-temperature extrusion, reinforced by rock phosphate particles acting as P fertilizer, and with encapsulation of Aspergillus niger as an oxidizing microorganism This structure was shown to be effective in significantly increasing S° oxidation while providing P by rock phosphate dissolution in an acid environment X-ray absorption near-edge structure (XANES) spectra provided information about P fixation in the soil after dissolution, showing that the composite structure with A niger modified the nutrient dynamics in the soil This fully integrated material (a smart fertilizer) is an innovative strategy for eco-friendly agronomic practices, providing high nutrient delivery with minimal so

Enzymatic production of cellulose nanofibers and sugars in a stirred-tank reactor: determination of impeller speed, power consumption, and rheological behavior

Abstract: An integrated biorefinery process is proposed here for the enzymatic production of cellulose nanofiber (CNF) and sugars in a stirred-tank reactor using eucalyptus cellulose pulp as feedstock. Process engineering variables required for scale-up such as impeller speed, power consumption, and rheological behavior were determined under different experimental conditions of solids loading (10 and 15% w/v) and enzyme dosage (5 and 10 mg/g). Based on the mixing time, an impeller speed rotation of 470 rpm was selected for provision of adequate homogenization of the medium. Total energy consumption ranged from 161 to 207 W h and showed that significantly lower power consumption could be achieved using 10 mg/g enzyme loading with 10% w/v solids. Evaluation of rheological behavior showed that transition to a turbulent flow regime during the enzymatic hydrolysis reaction resulted in a constant power number ranging from 2.06 to 2.51, which was also lower for 10 mg/g enzyme loading with 10% w/v solids. Integrated analysis of glucose released and CNF generated after enzymatic hydrolysis showed that glucose values varied from 42.0 to 90.6 g/L, corresponding to cellulose conversion ranging from 57.2 to 76.4%. These values are suitable for the microbial fermentation of sugars into biofuels, while leaving a useful amount of residual nanomaterial. The residual solids of the enzymatic reactions presented the characteristics of CNF, as shown by X-ray diffraction (XRD) analyses, with crystallinity index (CI) values of 72–81%, as well as by morphological analysis using field emission scanning electron microscopy (FEG-SEM), which revealed diameters in the range 18–31 nm, making this nanomaterial suitable for use in a wide range of industrial applications. The findings indicated the potential of using conventional stirred-tank reactors for enzymatic hydrolysis for the integrated production of CNF and glucose, hence contributing to the implementation of future large-scale biorefineries.

One-pot strategy for on-site enzyme production, biomass hydrolysis, and ethanol production using the whole solid-state fermentation medium of mixed filamentous fungi.

Abstract: The efficient use of renewable lignocellulosic feedstocks to obtain biofuels and other bioproducts is a key requirement for a sustainable biobased economy. This requires novel and effective strategies to reduce the cost contribution of the cellulolytic enzymatic cocktails needed to convert the carbohydrates into simple sugars, in order to make large-scale commercial processes economically competitive. Here, we propose the use of the whole solid-state fermentation (SSF) medium of mixed filamentous fungi as an integrated one-pot strategy for on-site enzyme production, biomass hydrolysis, and ethanol production. Ten different individual and mixed cultivations of commonly used industrial filamentous fungi (Aspergillus niger, Aspergillus oryzae, Trichoderma harzianum, and Trichoderma reesei) were performed under SSF and the whole media (without the extraction step) were used in the hydrolysis of pretreated sugarcane bagasse. The cocultivation of T. reesei with A. oryzae increased the amount of glucose released by around 50%, compared with individual cultivations. The release of glucose and reducing sugars achieved using the whole SSF medium was around 3-fold higher than obtained with the enzyme extract. The addition of soybean protein (0.5% w/w) during the hydrolysis reaction further significantly improved the saccharification performance by blocking the lignin and avoiding unproductive adsorption of enzymes. The results of the alcoholic fermentation validated the overall integrated process, with a volumetric ethanol productivity of 4.77 g/L.h, representing 83.5% of the theoretical yield. These findings demonstrate the feasibility of the proposed one-pot integrated strategy using the whole SSF medium of mixed filamentous fungi for on-site enzymes production, biomass hydrolysis, and ethanol production. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:671-680, 2018.

A Fed-Batch Strategy Integrated with Mechanical Activation Improves the Solubilization of Phosphate Rock by Aspergillus niger

Abstract: Solubilization of phosphate rock (PR) by microorganisms is an environmentally sustainable alternative to chemical processing for production of phosphate fertilizers. The effectiveness of this PR biological solubilization process is driven by the microbial production of organic acids that chelate the cations (mainly calcium) bound to phosphate. However, the biological solubilization efficiency has been limited by the PR solids content of cultivation systems and is still low for practical applications. Here, we propose a fed-batch strategy coupled with mechanical activation to improve the biological solubilization of PR by Aspergillus niger. An initial systematic study of the effect of the particle size of Itafos phosphate rock (IPR), a low reactivity phosphate mineral (P2O5, 20%), on the biological solubilization of phosphorus revealed that the particle size played a key role in IPR solubilization. Increases of available phosphate of up to 57% under submerged cultivation and 45% for solid-state culture wer...

Solid-State Fermentation for the On-Site Production of Cellulolytic Enzymes and Their Use in the Saccharification of Lignocellulosic Biomass

Abstract: The use of renewable lignocellulosic biomass as a feedstock for the production of fuels, chemicals, and high-value products within the biorefinery concept has been considered the most promising alternative to achieve the demands of the current bioeconomy. In this process, the conversion of biomass polysaccharides into soluble sugars via the biochemical route using enzymes is among the most feasible technological options. However, the cost of enzymes has a significant contribution to the overall conversion process and the development of novel bioprocess strategies to reduce enzyme cost is still a major challenge. The use of solid-state fermentation (SSF) for enzyme production has received increasing attention over the past years due to the inherent advantages of this cultivation system. In traditional SSF processes, after the cultivation period the enzymes synthesized by the microorganisms need to be extracted from the solid substrate by a conventional solid–liquid extraction step, with the final products after filtration being a liquid supernatant containing the enzymes of interest together with a solid residue. A potential way of avoiding production of this solid residue is to use the whole SSF for the saccharification of biomass. By using the whole SSF medium, the steps of extraction and filtration can be excluded from the overall process, providing advantages in terms of cost reduction and also avoiding the generation of waste streams. Moreover, the mycelium-bound enzymes can have a significant contribution to the hydrolysis yields. In this chapter, recent developments of the use of SSF for the on-site production of cellulolytic enzymes and their use on the hydrolysis of lignocellulosic biomass using the whole medium with isolated and mixed industrial-relevant fungal strains is discussed. The feasibility of using the whole SSF medium of filamentous fungi containing enzymes, fungal cells, and residual solid substrate as a potential strategy for biomass conversion is discussed in light of the recent literature.

Potential of Mangrove-Associated Endophytic Fungi for Production of Carbohydrolases with High Saccharification Efficiency

Abstract: The endophytic fungi represent a potential source of microorganisms for enzyme production. However, there have been only few studies exploiting their potential for the production of enzymes of industrial interest, such as the (hemi)cellulolytic enzymatic cocktail required in the hydrolysis of lignocellulosic biomass. Here, a collection of endophytic fungi isolated from mangrove tropical forests was evaluated for the production of carbohydrolases and performance on the hydrolysis of cellulose. For that, 41 endophytic strains were initially screened using a plate assay containing crystalline cellulose as the sole carbon source and the selected strains were cultivated under solid-state fermentation for endoglucanase, β-glucosidase, and xylanase enzyme quantification. The hydrolysis of a cellulosic material with the enzymes from endophytic strains of the Aspergillus genus resulted in glucose and conversion values more than twofold higher than the reference strains (Aspergillus niger F12 and Trichoderma reesei Rut-C30). Particularly, the enzymes from strains A. niger 56 (3) and A. awamori 82 (4) showed a distinguished saccharification performance, reaching cellulose conversion values of about 35% after 24 h. Linking hydrolysis performance to the screening steps played an important role towards finding potential fungal strains for producing enzymatic cocktails with high saccharification efficiency. These results indicate the potential of mangrove-associated endophytic fungi for production of carbohydrolases with efficient performance in the hydrolysis of biomass, thus contributing to the implementation of future biorefineries.

On-Site Production of Cellulolytic Enzymes by the Sequential Cultivation Method

Abstract: The conversion of renewable lignocellulosic biomass into fuels, chemicals, and high-value materials using the biochemical platform has been considered the most sustainable alternative for the implementation of future biorefineries. However, the high cost of the cellulolytic enzymatic cocktails used in the saccharification step significantly affects the economics of industrial large-scale conversion processes. The on-site production of enzymes, integrated to the biorefinery plant, is being considered as a potential strategy that could be used to reduce costs. In such approach, the microbial production of enzymes can be carried out using the same lignocellulosic biomass as feedstock for fungal development and biofuels production. Most of the microbial cultivation processes for the production of industrial enzymes have been developed using the conventional submerged fermentation. Recently, a sequential solid-state followed by submerged fermentation has been described as a potential alternative cultivation method for cellulolytic enzymes production. This chapter presents the detailed procedure of the sequential cultivation method, which could be employed for the on-site production of the cellulolytic enzymes required to convert lignocellulosic biomass into simple sugars.

Solubilization of phosphate rock by organic acids.

Abstract: Phosphate chemical fertilizers are extensively used to improve agricultural productivity. However, the production of these fertilizers is expensive and can cause environmental damage due to the use of high concentrations of sulfuric acid. Alternatively, microbial solubilization of phosphate rock (PR) is a potential strategy to obtain phosphate fertilizers (biofertilizers). This strategy relies on the ability of some microorganisms to produce organic acids which convert the insoluble PR phosphorus into soluble forms. This study aims to investigate the influence of different organic acids on PR solubilization. For that, the effect of nine organic acids on the solubilization of three phosphate sources was evaluated. The results showed that the effect of the organic acid on PR solubilization is dependent on the source and nature of the phosphate. Citric and oxalic acid were the most efficient organic acids to solubilize PR, being comparable to strong inorganic acids. The strategy proposed could contribute in future developments for the industrial production of phosphate fertilizer using organic acids.

Ethanol precipitation as a downstream processing step for concentration of xylanases produced by submerged and solid-state fermentation

Abstract: Xylanases have applications in different industries, being produced by microbial cultivations using submerged (SmF) or solid-state fermentation (SSF). Precipitation stands out as a potential method for the concentration of xylanases, especially with the use as ethanol as the precipitant due to its compatibility with the biorefinery concept. This paper presents a comparative laboratory scale study of ethanol precipitation of xylanases produced by Aspergillus niger cultivated under SSF and SmF. Precipitation conditions were selected according to a central composite design. Statistical analysis showed a significant effect of pH on the recoveries of total protein and xylanase activity. The kinetic profiles showed that a relatively short period of time (up to 15 min) was sufficient to recover most of the xylanase activity precipitated under the selected conditions. Xylanase recoveries of 65 and 79% were achieved for the SSF and SmF enzymatic complexes, respectively.

Studies of enzymatic hydrolysis of sugarcane bagasse pre-treated by steam explosion.

Abstract: Cellulosic ethanol (or G2) has been highlighted by its high renewable energy potential, and sugarcane bagasse is example of abundant raw material which may be used as agroindustrial byproduct for its production [1]. Bagasse is composed by lignocellulosic compounds, whose components are cellulose and recalcitrant biomass (hemicellulose and lignin), which surround the cellulose and render the enzymatic hydrolysis unfavorable [1]. Different pretreatments are studied to open the structure of recalcitrant biomass before processes for enzymatic hydrolysis, to allow the cellulose sugars monomers to be accessed [2,3]. Time Domain Nuclear Magnetic Resonance (TD-NMR) techniques were used in our research group to investigate the vapor blast pretreatment and showed the great efficiency in breaking the crystallinity of the cellulose in sugarcane bagasse [5]. The objective of this research was to analyze the enzymatic hydrolysis of previously treated bagasse by the steam explosion technique, from commercial enzyme Cellic ctec 2. Different enzyme loads 5, 10, 15 and 20 FPU / g were used, paired with enzymatic kinetics. The hydrolysis was terminated at the times of 24, 48, 72 and 96h. The methodologies used in the quantification of glucose and TRS samples after the hydrolysis period were performed with the enzymatic kit (glucose liquiform) and with the DNS reagent, for glucose and TRS, respectively. All readings were performed on the UV-VIS Spectrometer (Thermo Scientific). The best result of enzymatic load was 15 FPU / g at 48 h, glucose 13.9 g / L (table 1) and TRS was 20.3 g / L (table 2). These results were interesting, since are below the typical enzymatic load reported (20 FPU / g) and are in periods (48h) considered as viable for bioprocesses. The next stage of this study will be done in the fermentation processes of the sugars formed.