Effect of phenolic compounds from pretreated sugarcane bagasse on cellulolytic and hemicellulolytic activities

This work shows both cellulases and hemicellulases are inhibited and deactivated by water-soluble and acetone extracted phenolics from sugarcane bagasse pretreated at 10% (w/v) for 30 min in liquid hot water at 180 or 200°C. The dissolved phenolics in vacuum filtrate increased from 1.4 to 2.4 g/L as temperature increased from 180 to 200°C. The suppression of cellulose and hemicellulose hydrolysis by phenolics is dominated by deactivation of the β-glucosidase or β-xylosidase components of cellulase and hemicellulase enzyme by acetone extract at 0.2-0.65 mg phenolics/mg enzyme protein and deactivation of cellulases and hemicellulases by the water soluble components in vacuum filtrate at 0.05-2mg/mg. Inhibition was a function of the type of enzyme and the manner in which the phenolics were extracted from the bagasse.

Nanocellulose Production: Exploring the Enzymatic Route and Residues of Pulp and Paper Industry

Increasing environmental and sustainability concerns, caused by current population growth, has promoted a raising utilization of renewable bio-resources for the production of materials and energy. Recently, nanocellulose (NC) has been receiving great attention due to its many attractive features such as non-toxic nature, biocompatibility, and biodegradability, associated with its mechanical properties and those related to its nanoscale, emerging as a promising material in many sectors, namely packaging, regenerative medicine, and electronics, among others. Nanofibers and nanocrystals, derived from cellulose sources, have been mainly produced by mechanical and chemical treatments; however, the use of cellulases to obtain NC attracted much attention due to their environmentally friendly character. This review presents an overview of general concepts in NC production. Especial emphasis is given to enzymatic hydrolysis processes using cellulases and the utilization of pulp and paper industry residues. Integrated process for the production of NC and other high-value products through enzymatic hydrolysis is also approached. Major challenges found in this context are discussed along with its properties, potential application, and future perspectives of the use of enzymatic hydrolysis as a pretreatment in the scale-up of NC production.

Green synthesis of lignin nano- and micro-particles: Physicochemical characterization, bioactive properties and cytotoxicity assessment

Lignin particles (LPs) have gained prominence due to their biodegradability and bioactive properties. LP production at nano and micro scale produced from organosolv lignin and the understanding of size's effect on their properties is unexplored. This work aimed to produce and characterize lignin nanoparticles and microparticles using a green synthesis process, based on ethanol-solubilized lignin and water. Spherical shape LPs, with a mean size of 75 nm and 215 nm and with a low polydispersity were produced, as confirmed by transmission electron microscopy and dynamic light scattering. LPs thermal stability improved over raw lignin, and the chemical structure of lignin was not affected by the production method. The antimicrobial tests proved that LPs presented a bacteriostatic effect on Escherichiacoli and Salmonella enterica. Regarding the antioxidant potential, LPs had a good antioxidant activity that increased with the reaction time and LPs concentration. LPs also presented an antioxidant effect against intracellular ROS, reducing the intracellular ROS levels significantly. Furthermore, the LPs showed a low cytotoxic effect in Caco-2 cell line. These results showed that LPs at different scales (nano and micro) present biological properties and are safe to be used in different high value industrial sectors, such as biomedical, pharmaceutical and food.

Production of xylanase by Aspergilli using alternative carbon sources: application of the crude extract on cellulose pulp biobleaching

The ability of xylanolytic enzymes produced by Aspergillus fumigatus RP04 and Aspergillus niveus RP05 to promote the biobleaching of cellulose pulp was investigated. Both fungi grew for 4-5 days in liquid medium at 40 degrees C, under static conditions. Xylanase production was tested using different carbon sources, including some types of xylans. A. fumigatus produced high levels of xylanase on agricultural residues (corncob or wheat bran), whereas A. niveus produced more xylanase on birchwood xylan. The optimum temperature of the xylanases from A. fumigatus and A. niveus was around 60-70 degrees C. The enzymes were stable for 30 min at 60 degrees C, maintaining 95-98% of the initial activity. After 1 h at this temperature, the xylanase from A. niveus still retained 85% of initial activity, while the xylanase from A. fumigatus was only 40% active. The pH optimum of the xylanases was acidic (4.5-5.5). The pH stability for the xylanase from A. fumigatus was higher at pH 6.0-8.0, while the enzyme from A. niveus was more stable at pH 4.5-6.5. Crude enzymatic extracts were used to clarify cellulose pulp and the best result was obtained with the A. niveus preparation, showing kappa efficiency around 39.6% as compared to only 11.7% for that of A. fumigatus.

Liquid hot water pretreatment of multi feedstocks and enzymatic hydrolysis of solids obtained thereof

Agricultural feedstocks (brewers' spent grain - BSG, corncob - CC, corn husk - CH, wheat straw - WS and Luffa sponge - LS) were pretreated by liquid hot water (LHW) in order to increase cellulose recovery and enzymatic saccharification. LHW-pretreatment resulted in hemicellulose solubilization, and solids enriched in cellulose. Chemical analysis showed different susceptibilities of the feedstocks to LHW-pretreatment and enzymatic hydrolysis. Pretreated feedstocks presented higher crystallinity (determined through X-ray diffraction) and thermal stability (determined through thermogravimetric analysis) than untreated feedstocks. SEM images confirmed the effect of LHW-pretreatment on structural changes. Moreover, enzymatic hydrolysis and cellulose conversion to glucose (CCG) were improved for pretreated feedstocks, with exception of LS. CCG (in relation to glucose potential on solids) followed the order: BSG>CH>WS>CC>LS. LHW-pretreatment showed to be a good technology to pretreat multi feedstocks and for improving the enzymatic hydrolysis of recalcitrant agricultural feedstocks to sugars, which can be further converted to ethanol-fuel and other value-added chemicals.

Challenges of Biomass Utilization for Bioenergy in a Climate Change Scenario

The climate changes expected for the next decades will expose plants to increasing occurrences of combined abiotic stresses, including drought, higher temperatures, and elevated CO2 atmospheric concentrations. These abiotic stresses have significant consequences on photosynthesis and other plants' physiological processes and can lead to tolerance mechanisms that impact metabolism dynamics and limit plant productivity. Furthermore, due to the high carbohydrate content on the cell wall, plants represent a an essential source of lignocellulosic biomass for biofuels production. Thus, it is necessary to estimate their potential as feedstock for renewable energy production in future climate conditions since the synthesis of cell wall components seems to be affected by abiotic stresses. This review provides a brief overview of plant responses and the tolerance mechanisms applied in climate change scenarios that could impact its use as lignocellulosic biomass for bioenergy purposes. Important steps of biofuel production, which might influence the effects of climate change, besides biomass pretreatments and enzymatic biochemical conversions, are also discussed. We believe that this study may improve our understanding of the plant biological adaptations to combined abiotic stress and assist in the decision-making for selecting key agronomic crops that can be efficiently adapted to climate changes and applied in bioenergy production.

A novel xylan degrading β-D-xylosidase: purification and biochemical characterization

Aspergillus ochraceus, a thermotolerant fungus isolated in Brazil from decomposing materials, produced an extracellular β-xylosidase that was purified using DEAE-cellulose ion exchange chromatography, Sephadex G-100 and Biogel P-60 gel filtration. β-xylosidase is a glycoprotein (39 % carbohydrate content) and has a molecular mass of 137 kDa by SDS-PAGE, with optimal temperature and pH at 70 °C and 3.0-5.5, respectively. β-xylosidase was stable in acidic pH (3.0-6.0) and 70 °C for 1 h. The enzyme was activated by 5 mM MnCl₂ (28 %) and MgCl₂ (20 %) salts. The β-xylosidase produced by A. ochraceus preferentially hydrolyzed p-nitrophenyl-β-D-xylopyranoside, exhibiting apparent K(m) and V(max) values of 0.66 mM and 39 U (mg protein)⁻¹ respectively, and to a lesser extent p-nitrophenyl-β-D-glucopyranoside. The enzyme was able to hydrolyze xylan from different sources, suggesting a novel β-D-xylosidase that degrades xylan. HPLC analysis revealed xylans of different compositions which allowed explaining the differences in specificity observed by β-xylosidase. TLC confirmed the capacity of the enzyme in hydrolyzing xylan and larger xylo-oligosaccharides, as xylopentaose.

Multi-step approach to add value to corncob: Production of biomass-degrading enzymes, lignin and fermentable sugars

This work presents an integrated and multi-step approach for the recovery and/or application of the lignocellulosic fractions from corncob in the production of high value added compounds as xylo-oligosaccharides, enzymes, fermentable sugars, and lignin in terms of biorefinery concept. For that, liquid hot water followed by enzymatic hydrolysis were used. Liquid hot water was performed using different residence times (10-50min) and holding temperature (180-200°C), corresponding to severities (log(R₀)) of 3.36-4.64. The most severe conditions showed higher xylo-oligosaccharides extraction (maximum of 93%) into the hydrolysates and higher recovery of cellulose on pretreated solids (maximum of 65%). Subsequently, hydrolysates and solids were used in the production of xylanases and cellulases, respectively, as well as, pretreated solids were also subjected to enzymatic hydrolysis for the recovery of lignin and fermentable sugars from cellulose. Maximum glucose yield (100%) was achieved for solids pretreated at log(R₀) of 4.42 and 5% solid loading.

Development of a packed bed reactor for the removal of aromatic hydrocarbons from soil using laccase/mediator feeding system

Polyaromatic hydrocarbons (PAH) are persistent pollutants of great concern due to their potential toxicity, mutagenicity and carcinogenicity. A biotechnological approach to remove PAH from soil was evaluated in this work using a laccase mediator system. Initially, laccase was produced by fungal co-cultivation, using kiwi peels as substrate. The produced laccase was applied to PAH contaminated soil to evaluate its efficiency on enzymatic bioremediation. Results showed that laccase mediator system was effective in the degradation of pyrene, fluorene, chrysene and a lower extension anthracene. Mediators improved the PAH degradation and natural mediators (ferulic acid and p-coumaric acid) were as effective as the synthetic mediator ABTS. However, the process was not effective in the benzo[a]pyrene degradation, one of the most recalcitrant and toxic PAH. This low degradation rate could be related to the low activity of the laccase mediator system in an environment lacking water. To overcome this issue, a PAH contaminated soil degradation system was developed in packed bed reactor (PBR) fed with laccase/mediator. Continuous flow of laccase/mediator improved the PAH degradation, achieving 74.8 %, 71.9 %, 72.2 %, 81.8 % and 100 % degradation for fluorene, anthracene, phenanthrene, chrysene and pyrene, respectively. This system was able to degrade 96 % benzo[a]pyrene, which was 90 % higher than the degradation in batch system. Results indicated that the produced laccase as well as the fed-batch degradation system developed in PBR could be successfully applied in the degradation of soil PAH pollutants, with the advantage of achieving higher degradation rates than in simple batch, as well as being a faster and simpler process than microorganism bioremediation.

Production and action of an Aspergillus phoenicis enzymatic pool using different carbon sources

Aspergillus phoenicis is an interesting heat tolerant fungus that can synthesize enzymes with several applications in the food industry due to its great hydrolytic potential. In this work, the fungus produced high enzymatic levels when cultivated on inexpensive culture media consisting of flakes from different origins such as cassava flour, wheat fibre, crushed soybean, agro-industrial wastes, starch, glucose or maltose. Several enzymatic systems were produced from these carbon sources, but amylase was the most evident, followed by pectinase and xylanase. Traces of CMCases, avicelase, lipase, β-xylosidase, β-glucosidase and α-glucosidase activities were also detected. Amylases were produced on rye flakes, starch, oat flakes, corn flakes, cassava flour and wheat fibre. Significant amylolytic levels were produced in the culture medium with glucose or when this sugar was exhausted, suggesting an enzyme in the constitutive form. Cassava flour, rye, oats, barley and corn flakes were also used as substrates in the hydrolytic reactions, aiming to verify the liberation potential of reducing sugars. Corn flakes induced greater liberation of reducing sugars as compared to the others. Thin layer chromatography of the reaction end products showed that the hydrolysis of cassava flour liberated maltooligosaccharides, but cassava flour and corn, rye, oats and barley flakes were hydrolyzed to glucose. These results suggested the presence of glucoamylase and α-amylase as part of the enzymatic pool of A. phoencis.

Neosartorya glabra polygalacturonase produced from fruit peels as inducers has the potential for application in passion fruit and apple juices

Summary Polygalacturonases are enzymes with the biotechnological potential for use in fruit juice clarification and for the enhancement of filtration efficiency. The aim of this work was to assess the production of polygalacturonase by the fungus Neosartorya glabra by means of solid-state and submerged fermentation using fruit peel residues as the carbon source, and also apply the enzyme in the clarification and decrease in viscosity of passion fruit and apple juices. The highest polygalacturonase (4.52 U/g/h) production was obtained by means of submerged fermentation in Vogel´s medium (1964) containing orange peel – Bahia variety (Citrus sinensis), at a concentration of 1.5% (w/v, dried mass) at 30-35°C for 72 h. The polygalacturonase of the crude extract presented optimal activity at 60°C and pH 5.5. The enzyme retained around 90% of the initial activity after 180 minutes at 40°C, and 50% of the initial activity after 150 minutes at 50°C. The enzyme was shown to be stable at acid pH values (3.0-6.5) after 120 minutes at 25oC. All these favourable enzymatic properties make the polygalacturonase attractive for potential uses in the industry of pectin-rich fruit juices, since the application of the crude extract to passion fruit (Passiflora edulis) juice caused an 80% reduction in viscosity and 75% decrease in light absorbance. In the processing of apple pulp juice (Malus domestica), there was a 50% reduction in viscosity and 78% decrease in light absorbance.

Challenges in Using Ionic Liquids for Cellulosic Ethanol Production

The growing need to expand the use of renewable energy sources in a sustainable manner, providing greater energy supply security and reducing the environmental impacts associated with fossil fuels, finds in the agricultural by-product bioethanol an economically viable alternative with significant expansion potential. In this regard, a dramatic boost in the efficiency of processes already in place is required, reducing costs, industrial waste, and our carbon footprint. Biofuels are one of the most promising alternatives to massively produce energy sustainably in a short-term period. Lignocellulosic biomass (LCB) is highly recalcitrant, and an effective pretreatment strategy should also minimize carbohydrate degradation by diminishing enzyme inhibitors and other products that are toxic to fermenting microorganisms. Ionic liquids (ILs) have been playing an important role in achieving cleaner processes as a result of their excellent physicochemical properties and outstanding performance in the dissolution and fractionation of lignocellulose. This review provides an analysis of recent advances in the production process of biofuels from LCB using ILs as pretreatment and highlighting techniques for optimizing and reducing process costs that should help to develop robust LCB conversion processes.

The impact of severity of initial illness, determined by SOFA score, and presence of anemia on outcomes among patients requiring Extra Corporal Membrane Oxygenation (ECMO) support: A single center experience

Introduction

ECMO provides respiratory and circulatory support in critically ill patients. In our study, we report on a single center experience with ECMO and aim to identify the prognostic markers for survival to discharge from hospital.

Methods

A registry was maintained on all patients who underwent ECMO implantation from September 2012 till January 2016 at a single institution. The collected data was analyzed to identify baseline characteristics, outcomes including clinical variables predictive of poor outcome.

Results

A total of 29 patients underwent ECMO implantation. The average age of patients was 42 ± 18 years. 59% were males (N = 17). 19 cases had a cardiac indication for ECMO (66%) while 10 cases had a pulmonary indication (34%). On univariate analysis; presence of Multi-organ failure, SOFA score more than 18 and hemoglobin less than 10 g/dl at baseline and after ECMO removal were associated with increased 30 day mortality. Pearson correlation with 30 day mortality showed a positive correlation with MOF (+0.562, p = 0.002) and SOFA score >18 (+0.448, p = 0.015) and a negative correlation with anemia (−0.507, p = 0.005). 15 out of the total 29 patients (52%) died within 30 days of admission. Patients with MOF (log rank: 10.926, p = 0.001), SOFA score >18 (log rank: 7.758, p = 0.005) and hemoglobin <10 g/dl (log rank: 5.595, p = 0.018) had decreased survival on 30 day follow up.

Conclusions

Although the use of ECMO as a last line in the treatment of critical patients refractory to conventional treatment measures constitutes an important improvement in their care; with 48% overall survival; patient selection and timing of ECMO initiation remains challenging.

Patients who already had signs of MOF and a high SOFA score portended a poor response. Similarly for anemic patients. Hence the importance of consideration for ECMO use earlier in course of illness rather than later. Screening and aggressive treatment of anemia in those patients may help improve the outcomes.