New blend of renewable bioplastic based on starch and acetylated xylan with high resistance to oil and water vapor.

Renewable materials of biological origin exhibit attractive properties in relation to traditional plastics, as they can be partially or completely replaced, thereby reducing environmental impacts. Hemicelluloses are a group of polysaccharides that have expanded applications when acetylated. Acetylation can improve the mechanical strength and water vapor barrier properties of xylan-based bioplastics. By partially acetylating xylan in the present study, it was possible to use water as a solvent for the film-forming solution and starch as a second polysaccharide in the formation of bioplastics. Xylan was modified via partial chemical acetylation by varying the reaction time, solvent, and catalyst content. The bioplastics were formed by non-acetylated xylan and acetylated xylan with degrees of substitution (DS) of 0.45 and 0.9, respectively, with starch to form blends using glycerol as a plasticizer. Acetylation with DS 0.45 showed better results in increasing the hydrophilicity of the bioplastic. On the other hand, acetylation influenced the thermal stability of bioplastics, increasing the maximum temperature of the degradation rate from 302 °C to 329 °C and 315 °C, owing to changes in the crystallinity of the polymers. In addition to the modulus of elasticity 2.99 to 290.61 and 274.67 MPa for the non-acetylated bioplastic and the bioplastic with DS of 0.45 and 0.90, respectively. Thus, the films obtained presented suitable physicochemical properties for use in various industrial applications, such as active and intelligent packaging in the food sector.

Fungal Screening for Potential PET Depolymerization.

Approximately 400 billion PET bottles are produced annually in the world, of which from 8 to 9 million tons are discarded in oceans. This requires developing strategies to urgently recycle them. PET recycling can be carried out using the microbial hydrolysis of polymers when monomers and oligomers are released. Exploring the metabolic activity of fungi is an environmentally friendly way to treat harmful polymeric waste and obtain the production of monomers. The present study addressed: (i) the investigation of potential of strains with the potential for the depolymerization of PET bottles from different manufacturers (crystallinity of 35.5 and 10.4%); (ii) the search for a culture medium that favors the depolymerization process; and (iii) gaining more knowledge on fungal enzymes that can be applied to PET recycling. Four strains (from 100 fungal strains) were found as promising for conversion into terephthalic acid from PET nanoparticles (npPET): Curvularia trifolii CBMAI 2111, Trichoderma sp. CBMAI 2071, Trichoderma atroviride CBMAI 2073, and Cladosporium cladosporioides CBMAI 2075. The fermentation assays in the presence of PET led to the release of terephthalic acid in concentrations above 12 ppm. Biodegradation was also confirmed using mass variation analyses (reducing mass), scanning electron microscopy (SEM) that showed evidence of material roughness, FTIR analysis that showed band modification, enzymatic activities detected for lipase, and esterase and cutinase, confirmed by monomers/oligomers quantification using high performance liquid chromatography (HPLC-UV). Based on the microbial strains PET depolymerization, the results are promising for the exploration of the selected microbial strain.

Enzymatic Cocktail Formulation for Xylan Hydrolysis into Xylose and Xylooligosaccharides.

In the context of a biorefinery, lignocellulosic materials represent an important source of raw material for the bioconversion of cellulose, hemicellulose, and lignin into value-added products, such as xylose for fermentation, oligosaccharides, and bioplastics for packaging. Among the most abundant lignocellulosic materials in Brazil, sugarcane bagasse biomass stands out, as it is rich in cellulose and hemicellulose. In this context, through an experimental design, this study developed a robust enzyme cocktail containing xylanases and accessory enzymes to complete the hydrolysis of xylan from sugarcane bagasse, obtaining a low xylose yield and concentration (9% and 1.8 g/L, respectively, observed in experiment number 16 from the complete hydrolysis of a xylan assay), a fermentable sugar that is important in the production of second-generation ethanol, and a high xylooligosaccharides (XOS) yield and concentration (93.1% and 19.6 g/L, respectively, obtained from a xylooligosaccharides production assay); in general, xylan has prebiotic activities that favor an improvement in intestinal functions, with immunological and antimicrobial actions and other benefits to human health. In addition to completely hydrolyzing the sugarcane bagasse xylan, this enzymatic cocktail has great potential to be applied in other sources of lignocellulosic biomass for the conversion of xylan into xylose and XOS due to its enzymes content, involving both main chain and pendant groups hydrolysis of hemicelluloses.

Production and assessment of the biodegradation and ecotoxicity of xylan- and starch-based bioplastics.

Developing novel renewable (and preferably biodegradable) materials has become recurrent due to the growing concerns with environmental impacts of high volumes of plastic waste produced from oil-based sources over the past decades. This study aimed at developing bioplastics from a mixture of starch and xylan in variable ratios, and the combined effect of α-cellulose and holocellulose extracted from sugarcane bagasse added to the process. The disintegration of bioplastics was evaluated in both soil and composting. The ecotoxicity analyses with Saccharomyces cerevisiae, Bacillus subtilis and seeds of Cucumis sativus were conducted after disintegration. All formulations based on 5% (w/v) of total polysaccharides were dried at 30 °C and resulted in homogeneous and non-brittle bioplastics. The composting results showed that all bioplastic formulations disintegrated in 3 days, whereas the 25/75% (xylan/starch, w/w) formulation vanished in soil within 13 days. The ecotoxicity data showed no inhibition of microbial growth after biodegradation, yielding 100% of seed germination. Despite the positive influence of the bioplastic degradation on the root and hypocotyl growth, temporary inhibition of C. sativus tissues exposed to soil washing (10 days of disintegration) was observed. The study demonstrated that xylan/starch bioplastics result in non-ecotoxic biodegradable materials.

Advantages and Disadvantages of Bioplastics Production from Starch and Lignocellulosic Components.

The accumulation of plastic wastes in different environments has become a topic of major concern over the past decades; therefore, technologies and strategies aimed at mitigating the environmental impacts of petroleum products have gained worldwide relevance. In this scenario, the production of bioplastics mainly from polysaccharides such as starch is a growing strategy and a field of intense research. The use of plasticizers, the preparation of blends, and the reinforcement of bioplastics with lignocellulosic components have shown promising and environmentally safe alternatives for overcoming the limitations of bioplastics, mainly due to the availability, biodegradability, and biocompatibility of such resources. This review addresses the production of bioplastics composed of polysaccharides from plant biomass and its advantages and disadvantages.

Vinasse from sugarcane bagasse (hemicellulose) acid hydrolysate and molasses supplemented: biodegradability and toxicity.

Vinasse sugarcane is a valuable byproduct of the ethanol production process, presenting a perspective of volume increase with the development of second generation ethanol (2GE). However, this byproduct needs new methods of treatment and management for sustainability. Besides that, 2GE vinasse can be associated with some compounds (such as furan derivatives, phenolic compounds and organic acids), depending on the process used to solubilize hemicellulose, which could compromise vinasse destination or utilization. For this reason, detoxification methods of the hemicellulosic hydrolysates, from which vinasse is obtained in subsequent steps, are crucial. This study aimed to investigate whether the biological detoxification of vinasse from 2GE presents a difference concerning the microbial activity of biodegradation and toxicity when compared to vinasse without the detoxification process. Two vinasses (1, before; and 2, after detoxification) from fermented sugarcane bagasse (hemicellulose fraction) acid hydrolysate (supplemented with its molasses), under different concentrations: 2.5; 5 e 10% were evaluated. Their physicochemical characterization, biodegradation microbial activity (through Bartha and Pramer respirometric method, with total count of heterotrophic bacteria and fungi), and toxicity evaluation (through bioassays with Lactuca sativa at concentraction: 2.5; 5 e 10% and Daphnia similis to 1.5; 2.5; 3.5; 4.5; 5 and 10%) were performed. The results indicated high mineral and organic matter, which under a specific circumstance (2.5% of soil conditioning), enabled high efficiency in biodegradation (>80%). The bioassays with L. sativa signaled negative effect for radicular growth when the vinasses were applied at a concentration of 5 and 10% (sublethal effect and delayed root growth). Acute effects were observed in D. similis, with 50% of immobilization, at concentrations of 4.13% and 4.74% for vinasses 1 and 2, respectively. These results indicate that the biodegradation of vinasse from sugarcane bagasse acid hydrolysate occurs at relatively low levels (up to 5%) and suggests that higher concentrations (≥10%) may impair the growth of soil-associated microorganisms.

Detoxification of sugarcane bagasse hydrolysate with different adsorbents to improve the fermentative process.

Second generation ethanol has the prospect of becoming an important bioenergy alternative. The development of this technology is associated with the lignocellulosic materials' use, with emphasis on agricultural and agroindustrial by-products from which fermentable sugar can be produced. The acid hydrolysis depolymerizes the hemicellulose releasing mainly xylose. Subsequently, the cellulose can be converted into glucose by enzymatic hydrolysis. However, the acid hydrolysis produces toxic compounds, such as furan derivatives, phenolics, and organic acids, which are harmful to fermentative microorganisms. This study investigated different acid concentrations in the sulfuric acid hydrolysis of sugarcane bagasse (1- 5% m/v) and the use of adsorbents with the prerogative to improve the acid hydrolysate (AH) quality for microbial ethanolic fermentation. Cell growth and fermentative yield of Saccharomyces cerevisiae (PE-2) and Scheffersomyces stipitis (NRRL Y-7124) were evaluated. AH was used as a source of pentoses (17.7 g L-1) and molasses (ME) sugarcane as source of hexoses (47 g L-1). The following adsorbents were used: activated charcoal, clay, hydrotalcite and active and inactive cells of PE-2 and NRRL Y-7124, at concentrations ranging (1 - 8% m/v). Results of cell growth and chemical characterization allowed to select the most effective adsorbents with emphasis for active cells that removed 66% furfural and 51% 5-(hydroxymethyl) furfural) (5-HMF) and alcoholic productivity of 23.5 g L-1 in AH and ME substrates, in the presence of mixed culture. These results indicate the application of active yeast cells in the detoxification of acid hydrolysates of the sugarcane bagasse previously to the fermentation.

Endoglucanase activity in Neoteredo reynei (Bivalvia, Teredinidae) digestive organs and its content.

Cellulolytic enzymes have been studied in several organisms, such as insects, molluscs and other organisms, which can have enzymes endogenously produced or by symbiotic microorganisms. These enzymes are responsible for breaking down the cellulosic material upon which these organisms feed, probably with the aim of assimilating the sugars and nutrients. As Teredinidae bivalves grown in mangrove trees, this study aimed to measure endo-ß-1,4-glucanase activity in different organs and its content. Endo-ß-1,4-glucanase activity was detected in different organs of the Teredinidae bivalves, including gills and digestive organs tissues and its content. Moreover, organisms such as teredinids grow up inside wood and this process could perhaps be related to creating growth space. All the endoglucanase extracts, from organs tissues and contents, showed maximum activity at 40 °C. The maximum activity was observed at pH 5.5 for all the extracts, except for intestine tissue, which maximum was at pH 6. Moreover, some of the extracts showed a different profile of the activity as a pH influence, suggesting different distribution of enzymes over the digestive system of the teredinids. The results suggested that the endo-ß-1,4-glucanase from Teredinidae could be applied in process that requires low temperature, such as, simultaneous saccharification and fermentation, since it presents lower optimum temperature in comparison to enzymes from terrestrial microorganisms.

Chemical input reduction in the arabinoxylan and lignocellulose alkaline extraction and xylooligosaccharides production.

Lignocellulosic material breakdown by hydrolysis is an important step to open new perspectives for bioenergy and special foods production like prebiotic xylooligosaccharides. Improvement of lignocellulose and arabinoxylan alkaline extraction from sugarcane bagasse and enzymatic hydrolysis were performed. Treatments 1 (10% KOH at 70°C), 3 (5% KOH at 121°C) and ZD method (24% KOH at 35°C) showed solid lignocellulose recovery of respectively 75.2%, 74.2% and 73%. A range of 24.8-27% extracted material with high arabinoxylan content (72.1-76.3%) was obtained with these treatments. Treatment 1 and 3 exhibited great KOH reduction in the method reaction, 54.1% and 76.2%, respectively. Likewise, in treatment 3 there was a decrease in ethanol consumption (40.9%) when compared to ZD method. The extracted arabinoxylan showed susceptibility to enzymatic hydrolysis with high solid loading (7%) since Trichoderma reesei xylanases were advantageous for xylose production (54.9%), while Aspergillus fumigatus xylanases achieved better XOS production (27.1%).

Lignin enrichment and enzyme deactivation as the root cause of enzymatic hydrolysis slowdown of steam pretreated sugarcane bagasse.

The enzymatic hydrolysis (EH) rate normally decreases during the hydrolysis, leaving unhydrolyzed material as residue. This phenomenon occurs during the hydrolysis of both cellulose (avicel) and lignocellulosic material, in nature or even pretreated. The progression of EH of steam pretreated sugarcane bagasse was associated with an initial (fast), intermediate (slower) and recalcitrant (slowest) phases, at glucan to glucose conversion yields of 61.7, 81.6 and 86%, respectively. Even though the EH of avicel as a simpler material than steam pretreated sugarcane bagasse, EH slowdown was present. The less thermo-stable endo-xylanase lost 58% of initial enzyme activity, followed by ß-glucosidase that lost 16%, culminating in FPase activity loss of 30% in the first 24hours. After 72hours of EH the total loss of FPase activity was 40% compared to the initial activity. Analysis of the solid residue from EH showed that lignin content, phenolic compounds and ash increased while glucan decreased as hydrolysis progressed. During the initial fast phase of EH, the total solid residue surface area consisted predominantly of internal surface area. Thereafter, in the intermediate and recalcitrant phases of EH, the ratio of external:internal surface area increased. The proposed fiber damage and decrease in internal surface area, probably by EH action, was visualized by scanning electron microscopy imagery. The higher lignin/glucan ratio as EH progressed and enzyme deactivation by thermo instability were the main effects observed, respectively to substrate and enzyme.

Relationship between physicochemical properties and enzymatic hydrolysis of sugarcane bagasse varieties for bioethanol production.

The structural and physicochemical characteristics are associated with resistance of plant cell walls to saccharification by enzymes. The effect of physicochemical properties on glucose yield of bagasse from different varieties of sugarcane at low and high enzyme dosages was investigated. The result showed that glucose yield at low enzyme dosage was positively linear correlated with the yield at high enzyme dosage, for both the untreated and pretreated materials. The pretreatment significantly increased the accessibility of substrates by enzyme due to the increase of internal and external surface area. Glucose yield also showed a linear correlation with dye adsorption. However, the increase in glucose yield as a result of pretreatment did not correlate with the increases in crystallinity index and decreases in degree of polymerization. The Principal Component Analysis of infrared data indicated that lignin was the main component that differentiated the varieties before and after pretreatment. These results suggested that the key differences in pretreatment responses among varieties could be mainly attributed to their differences in the internal and external surface area after pretreatment.

Xylooligosaccharides production from alkali-pretreated sugarcane bagasse using xylanases from Thermoascus aurantiacus.

Sugarcane bagasse hemicellulose was isolated in a one-step chemical extraction using hydrogen peroxide in alkaline media. The polysaccharide containing 80.9% xylose and small amounts of L-arabinose, 4-O-methyl-D-glucuronic acid and glucose, was hydrolyzed by crude enzymatic extracts from Thermoascus aurantiacus at 50 degrees C. Conditions of enzymatic hydrolysis leading to the best yields of xylose and xylooligosaccharides (DP 2-5) were investigated using substrate concentration in the range 0.5-3.5% (w/v), enzyme load 40-80 U/g of the substrate, and reaction time from 3 to 96 h, applying a 2(2) factorial design. The maximum conversion to xylooligosaccharides (37.1%) was obtained with 2.6% of substrate and xylanase load of 60 U/g. The predicted maximum yield of xylobiose by a polynomial model was 41.6%. Crude enzymatic extract of T. aurantiacus generate from sugarcane bagasse hemicellulose 39% of xylose, 59% of xylobiose, and 2% of other xylooligosaccharides.