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The pulp and biorefining industries produce their waste as lignin, which is one of the most abundant renewable resources. So far, lignin has been remained severely underutilized and generally burnt in a boiler as a low-value fuel. To demonstrate lignin's potential as a value-added product, we will review market opportunities for lignin related applications by utilizing the thermo-chemical/biological depolymerization strategies (with or without catalysts) and their comparative evaluation. The application of lignin and its derived aromatics in various sectors such as cement industry, bitumen modifier, energy materials, agriculture, nanocomposite, biomedical, H

Rice straw has a great potential for ethanol production due to its richness in polysaccharides and abundant availability, however, for efficient utilization of these polysaccharides, size reduction is a prerequisite step. Therefore, biomass particle size plays a vital role for cellulosic ethanol commercialization. In this study, the effects of rice straw particle size on dilute acid pretreatment efficiency and enzymatic hydrolysis are investigated. Different sizes; 5, 10 and 20 mm were subjected to dilute acid pretreatment in a continuous pilot scale system with a horizontal screw feeder reactor followed by enzymatic hydrolysis at varying solids (10 and 15%) and enzyme dosages (5 and 10 FPU/g of pretreated residue). The glucan hydrolysis for 5, 10 and 20 mm are 65.6, 80.0 and 60.0% using 5 FPU and 79.5, 93.4 and 72.8% using 10 FPU/g pretreated residue respectively at 10% loading, whereas, at 15% it is significantly lower in respective experiment. Overall sugar recovery with 10 mm is 63.8 and 72.9% with 5 and 10 FPU respectively. RS with 10 mm biomass particle size at both solid loadings and enzyme dosages resulted in much higher enzymatic hydrolysis than others and in turn the overall sugar recovery and this was found to be due to the variation in the degradation products and pseudolignin contents in the pretreated biomass. The insight into the structural intricacies of biomass after pretreatment are studied using FT-IR and SEM revealing significant changes in biomass properties responsible for improved sugar recovery.

Conversion of lignocellulosic biomass to fuels and chemicals has attracted immense research and development around the world. Lowering recalcitrance of biomass in a cost-effective manner is a challenge to commercialize biomass-based technologies. Deep eutectic solvents (DESs) are new 'green' solvents that have a high potential for biomass processing because of their low cost, low toxicity, biodegradability, easy recycling and reuse. This article discusses the properties of DESs and recent advances in their application for lignocellulosic biomass processing. The effectiveness of DESs in hydrolyzing lignin-carbohydrate complexes, removing lignin/hemicellulose from biomass as well as their effect on biomass deconstruction, crystallinity and enzymatic digestibility have been discussed. Moreover, this review presents recent findings on the compatibility of natural DESs with enzymes and microorganisms.

Bioethanol from lignocellulosic biomass (LCB) is considered as an alternative solution to replace the fossil-based liquid fuels and thus causes the reduction in the environmental pollution in a sustainable manner. LCB is predominantly composed of cellulose, hemicellulose, lignin, ash, and extractives, which are interconnected with each other intricately leading to a rigid and recalcitrant structure. In its native form, enzymes could not access the carbohydrates and pretreatment is the key to disintegrate the highly ordered LCB structure and expose the cellulose and hemicellulose for enzymatic hydrolysis and release fermentable sugars. However, pretreatment is the high CAPEX (capital expenditure) and energy intensive step and it may represent up to 20%–30% of the ethanol costs. Thus, cost-effective and energy efficient pretreatment is the key to harness the potential of this largely untapped natural bioresource. Among various pretreatment strategies only a few have been validated at commercial scale (such as dilute acid, steam explosion, and hydrothermal) while most of them have only been evaluated at lab, pilot, or demonstration scale only (e.g., ammonia, alkali, biological, ionic liquids) majorly due to the poor economics and process complexity challenges. This study provides a detailed insight of the mechanism of action of different pretreatments, its impact on structural and functional properties of LCB with a focus on enzymatic hydrolysis yields. The analytical tools and techniques used to evaluate the substrate properties affected by the pretreatment and its correlation with enzymatic hydrolysis is discussed. Finally, the current status of pretreatment and enzymatic hydrolysis of different biomass at varied temperatures and solid loadings is illustrated to understand their impacts and implications.

Lignin is produced as a byproduct in cellulosic biorefinery as well in pulp and paper industries and has the potential for the synthesis of a variety of phenolics chemicals, biodegradable polymers, and high value-added chemicals surrogate to conventional petro-based fuels. Therefore, in this critical review, we emphasize the possible scenario for lignin isolation, transformation into value addition chemicals/materials for the economic viability of current biorefineries. Additionally, this review covers the chemical structure of lignocellulosic biomass/lignin, worldwide availability of lignin and describe various thermochemical (homogeneous/heterogeneous base/acid-catalyzed depolymerization, oxidative, hydrogenolysis etc.) and biotechnological developments for the production of bio-based low molecular weight phenolics, i.e. polyhydroxyalkanoates, vanillin, adipic acid, lipids etc. Besides, some functional chemicals applications, lignin-formaldehyde ion exchange resin, electrochemical and production of few targeted chemicals are also elaborated. Finally, we examine the challenges, opportunities and prospects way forward related to lignin valorization.

Novel and sustainable pretreatment approaches are desired to improve the techno-commercial feasibility of biorefineries in the future. In this study, 10 renewable deep eutectic solvents (DESs) were evaluated for their pretreatment efficiency at facile conditions with sugar cane bagasse as substrate and compared with conventional pretreatment approaches (dilute alkali, dilute acid, and ionic liquid (IL)) for lignin removal, saccharification yield, cellulose accessibility, crystallinity, and physiochemical properties. Although, the highest delignification was obtained with dilute alkali (59.7%) and choline chloride:lactic acid or ChCl:LA (50.6%), the maximum enzymatic conversion of 98.0% and 90.4% was observed with IL (1-butyl-3-methylimidazolium acetate) and ChCl:LA, respectively. uclear magnetic resonance analysis of ChCl:LA-derived lignin showed selective removal of guaiacyl lignin without condensation structure formation observed. Interestingly, unlike IL, the lignin was substantially depolymerized afte...

b-glucosidases are very important in the improvement of cellulose degradation rates by diminishing the inhibition of end products. Although, cellulase cost has reduced significantly in last decade but still the high costs of biomass saccharification is one of the main challenges for the commercialization of ethanol from LC biomass. In this work, -glucosidase immobilization in calcium alginate was optimized using response surface methodology. 89% immobilization efficiency was achieved under optimum conditions (i.e., calcium alginate 4.19% (w/v), calcium chloride 0.14 M and -glucosidase 4.42% (v/v) or 57.46 U/mL of reaction mixture). pH and temperature optima of both free and immobilized -glucosidase was found to be 5 and 50 C, respectively. Enzyme kinetics of free and immobilized -glucosidase was done to evaluate Michaelis constant (Km) and Vmax values, using pnitrophenyl- -D-glucopyranoside (pNPG) as the substrate and glucose as inhibitor. Increase in Km value (0.995 mM) for immobilized -glucosidase as compared to the free -glucosidase (0.617 mM) was observed. A decrease in Vmax from (1191.74 mol min-1 for free -glucosidase) to (736.65 mol min-1 immobilized -glucosidase) was observed after immobilization. Glucose was found to inhibit -glucosidase by competitive mode of inhibition (Ki= 3.01 mM). Studies were carried out in a batch reactor using 2% cellobiose, 0.1 M sodium acetate buffer, 5 pH and 50 C. 84% cellobiose to glucose conversion was found in first cycle which was about 67% in fifth cycle. This study suggests that enzyme immobilization improved enzyme stability, substrate inhibition and permits enzyme reusability.

3D printing by fused deposition modeling (FDM) is an advanced additive manufacturing technology for making thermoplastic-based structures. Several studies have recently investigated 3D printing of polylactic acid (PLA) with biomass resources like cellulose, hemicellulose, lignin and whole biomass. Such biodegradable composites are better for the environment and can be used to replace non-biodegradable composites in a variety of applications. Therefore, a deep understanding of printing such biocomposites is needed for supporting such manufacturing. Recent developments focused on FDM printing of PLA filled with biomass resources have been critically reviewed to reveal the intricate aspects of manufacturing of such materials and characterization of the changes caused by biomass-based fillers. Properties of high molecular weight PLA, essentials of printing with PLA and conditions for filament extrusion and printing of biocomposites are discussed. Characterization results from mechanical testing, thermal analysis, viscoelastic properties, imaging and spectroscopy are reviewed for understanding the impact of filling biomass resources in PLA by printing. The latter sections discuss applications, upcycling & recycling and future opportunities for biorefineries.

The surplus availability of rice straw, its limited usage, and environmental pollution caused by its inefficient burning has fostered research for its valorization to biofuels. This review elucidates the current status of rice straw potential around the globe along with recent advances in revealing the critical factors responsible for its recalcitrance and chemical properties. The role and accumulation of high silica content in rice straw has been elucidated with its impact on enzymatic hydrolysis in a biorefinery environment. The correlation of different pre-treatment approaches in modifying the physiochemical properties of rice straw and improving the enzymatic accessibility has also been discussed. This study highlights new challenges, resolutions, and opportunities for rice straw based biorefineries. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd

In this study, commercial surfactants have been investigated at economically viable dosage to enhance the enzymatic saccharification of pretreated wheat straw at high solid loadings. Twenty one surfactants were evaluated with pilot scale pretreated wheat straw and mechanism of surfactant action has been elucidated. One surfactant has improved the saccharification of dilute acid wheat straw (DAWS) by 26.4% after 24 h and 23.1% after 48 h while, steam exploded wheat straw (SEWS) saccharification was increased by 51.2% after 24 h and 36.4% after 48 h at 10% solid loading. At 20% solid loading, about 31% increase in yield was obtained on DAWS and about 55% on SEWS after 48 h. Further, lignin was isolated from pretreated wheat straws and characterized which revealed that SEWS derived lignin was more hydrophobic than DAWS lignin. This investigation suggests that surfactant supplementation during saccharification is an effective strategy to achieve higher saccharification yield.

Co-culture of fungal strains Penicillium janthinellum EMS-UV-8 (E), Penicillium funiculosum strain P (P) and Aspergillus sp. strain G (G) and blending of their crude cellulase were evaluated for improvements in cellulase activities as well as for enhanced hydrolysis of dilute acid pretreated wheat straw (PWS). The blending of crude enzymes of P and E enhanced the hydrolysis of PWS more effectively due to synergism in cellulolytic enzyme activities. Here, three types of blends were made on the basis of equal FPUs, equal protein content or fixed volume containing different proportions of individual enzymes, the former blend hydrolyzed 42.6% of PWS due to the 98%,62%, 64% and 34% synergistic enhancement in endo-glucanase, cellulase (FPU), β-glucosidase and xylanase activities, respectively. Hydrolysis at 10% solid loading of PWS in roller bottle reactor with this blend further enhanced hydrolysis yield to 74% within 24 h, which was much better than the corresponding hydrolysis yields of individual (38.1% by E and 61.5% by P) or the commercial enzyme (62.3%). This study proved that synergistic blends of cellulases from two Penicillium spp. are cost-effective tools for efficient wheat straw hydrolysis for on-site biofuel production.

Disaccharides or their derivatives were analyzed for the induction of cellulases by Penicillium janthinellum EMS-UV-8 mutant. Among seven (Crocin, Gentiobiose, Cellobiose, α-D-Cellobiose octaacetat...

Enzymatic hydrolysis at high solids loading has the potential to reduce both capital and operational expenditures. Here, pretreatment of rice straw (PRS) with dilute acid was carried out at a pilot scale (250 kg per day) at 162°C for 10 min and 0.35% acid concentration, followed by enzymatic hydrolysis at different total solids loadings. It showed that although the total sugar concentration increased from 48 to 132 g/l, glucan conversion reduced by 27% (84–66.2%) with increasing solids from 5 to 20% in batch mode. Therefore, two different fed-batch approaches were evaluated to improve the glucan conversion by the sequential addition of a substrate and/or enzyme. At 20% solid loadings and a 3 filter paper units/g enzyme dosage, the highest glucan conversion obtained was 66% after 30 h of hydrolysis in batch mode. However, in an optimized fed-batch approach, the glucan yield was improved to 70% by simply dividing the substrate feeding into three batches, that is, 50% at 0 h, 25% each after 4 h, and 8 h of hydrolysis reaction. The addition of surfactant (Ecosurf E6) further improved the conversion to 72% after 30 h. The role of critical factors, that is, inhibitors, enzyme–lignin binding, and viscosity, was investigated during the course of hydrolysis in the batch and fed-batch approaches. This study suggests a sustainable approach for improved hydrolysis at high solids loadings by fine-tuning a simple process.

There is tremendous potential of plant growth-promoting rhizobacteria (PGPR) in the development of agriculture in a sustainable manner. PGPR live in a close association with plants and help in promoting their growth either directly or indirectly. Efficient PGPR detection in a quick and reliable manner is the need of the hour for their judicious implementation in improving the agriculture yields. Here, a recent up-to-date overview of the PGPR detection methods with a focus on novel immunobased tools and techniques for PGPR detection is presented. The immunobased techniques provide a cost-effective, fast, and highly specific alternative for PGPR detection. This study has implication in developing better understanding for the suitable methods of PGPR detection as per the needs of the research application.

Rhizosphere had a complex dynamic ecological relationship of plant and microbe. They are involved in the secretion of wide array of chemicals that can be classified as signaling compounds, antipathogenic compounds, growth regulators, and nutrient solubilizers. Thus, unraveling these interactions and the chemicals involved in these bilateral signaling can enable us to have a sustainable agriculture. Recently, ultrahigh-throughput techniques offered the potential to explore these interactions in holistic manner. Transcriptomics and metabolomics have led to novel investigations on plant development and stress responses. Additionally, these techniques had changed scenario of PGPR and biocontrol studies that previously involved single-aspect studies through traditional techniques. In this chapter, we summarize the aspects of rhizosphere metabolite studies including their potential challenges and opportunities.

Study describes the production of cellulases by Penicillium janthinellum EMS-UV-8 using untreated wheat straw (WS), treated WS (acid, alkali, steam exploded, organo-solv) and pure cellulosic substrates (avicel, cellulose-II and carboxymethyl cellulose). Severely pretreated WS and cellulose-II produced more cellulolytic enzymes than untreated samples. XRD and FTIR analysis revels that the increase in the amorphous structure of pretreated WS/cellulose increases enzyme production. Enzyme samples prepared using different substrates were used for the hydrolysis of dilute acid treated wheat straw (DATWS), steam exploded wheat straw (SEWS) and avicel. The enzyme prepared using untreated WS gave more hydrolysis of DATWS and SEWS than the enzyme prepared using pretreated WS or pure cellulosic substrates. This revels that more diverse/potential enzymes were secreted by P. janthinellum EMS-UV-8 mutant using untreated WS. This study may contribute in production of efficient enzyme mixture/cocktail by single fungal strain for economic conversion of biomass to sugars.