Advances in enzymatic conversion of biomass derived furfural and 5-hydroxymethylfurfural to value-added chemicals and solvents.

The progress of versatile chemicals and bio-based fuels using renewable biomass has gained ample importance. Furfural and 5-hydroxymethylfurfural are biomass-derived compounds that serve as the cornerstone for high-value chemicals and have a myriad of industrial applications. Despite the significant research into several chemical processes for furanic platform chemicals conversion, the harsh reaction conditions and toxic by-products render their biological conversion an ideal alternative strategy. Although biological conversion confers an array of advantages, these processes have been reviewed less. This review explicates and evaluates notable improvements in the bioconversion of 5-hydroxymethylfurfural and furfural to comprehend the current developments in the biocatalytic transformation of furan. Enzymatic conversion of HMF and furfural to furanic derivative have been explored, while the latter has substantially overlooked a foretime. This discrepancy was reviewed along with the outlook on the potential usage of 5-hydroxymethylfurfural and furfural for the furan-based value-added products' synthesis.

Evaluating the potential of engineered Trichoderma atroviride and its laccase-mediated system for the efficient bioconversion of 5-hydroxymethylfufural.

5-Hydroxymethylfurfural (HMF) is a fermentation inhibitor which is formed during acid-based thermochemical pre-treatment of biomass. The present study involves two approaches for HMF conversion; the first includes screening and identification of fungal strains which produce oxidoreductases for HMF bioconversion, and thereafter evaluating their roles in HMF conversion. Out of the ten fungal strains screened, genetically engineered Trichoderma atroviride (Lac+) showed maximum HMF bioconversion and the activities of ligninolytic enzymes produced were noted. Maximum HMF conversion of 99% was achieved at pH 5.0 and 30 °C when 72 h old 10% inoculum of T. atroviride (Lac+) was utilized for 6 days. Based on the fungal bioconversion of HMF to 2, 5 diformylfuran with 58% yield, laccase was observed to influence the conversion process. Thus, a comparative study was established on HMF conversion by 100 U/mL of commercial laccases and partially purified laccase from T. atroviride (Lac+). In the presence of TEMPO, T. atroviride laccase showed comparable HMF conversion to commercial laccases, which establishes the efficiency of fungi and ligninolytic enzymes in bioconversion of HMF to value-added products.

Utilization of surface-active compounds derived from biosolids to remediate polycyclic aromatic hydrocarbons contaminated sediment soil.

In the present study, surface-active compounds (SAC) were extracted from biosolids using an alkaline treatment process. They were tested for their remediation efficiency of crude oil-contaminated sediment soil and was compared with Triton x-100. The SAC exhibited a similar soil washing efficiency to that of the commercial Triton x-100, and under the optimized soil washing parameters, SAC exhibited a maximum of 91% total polycyclic aromatic hydrocarbons removal. Further, on analysing the toxicity of the soil residue after washing, it was observed that SAC from biosolids washed soil exhibited an average of 1.5-fold lesser toxicity compared to that of Triton x-100 on different test models-earthworm, a monocot, and dicot plants. The analysis of the key soil parameters revealed that the commercial surfactant reduced the soil organic matter and porosity by an average of 1.3-fold compared to SAC. Further, the ability of surfactants to induce toxicity was confirmed by the adsorption of the surfactants on the surface of the soil particles which was in the order of Triton x-100 > SAC. Thus, this study suggests that SAC can be applied as an effective bioremediation approach for contaminated soil for a greener and sustainable ecosystem.

Laccase production by Pleurotus ostreatus using cassava waste and its application in remediation of phenolic and polycyclic aromatic hydrocarbon-contaminated lignocellulosic biorefinery wastewater.

The treatment of contaminants from lignocellulosic biorefinery effluent has recently been identified as a unique challenge. This study focuses on removing phenolic contaminants and polycyclic aromatic hydrocarbons (PAHs) from lignocellulosic biorefinery wastewater (BRW) applying a laccase-assisted approach. Cassava waste was used as a substrate to produce the maximum yield of laccase enzyme (3.9 U/g) from Pleurotus ostreatus. Among the different inducers supplemented, CuSO4 (0.5 mM) showed an eight-fold increase in enzyme production (30.8 U/g) after 240 h of incubation. The catalytic efficiency of laccase was observed as 128.7 ± 8.47 S-1mM-1 for syringaldazine oxidation at optimum pH 4.0 and 40 °C. Laccase activity was completely inhibited by lead (II) ion, mercury (II) ion, sodium dodecyl sulphate, sodium azide and 1,4 dithiothretiol and induced significantly by manganese (II) ion and rhamnolipid. After treating BRW with laccase, the concentrations of PAHs and phenolic contaminants of 1144 µg/L and 46160 µg/L were reduced to 96 µg/L and 16100 µg/L, respectively. The ability of laccase to effectively degrade PAHs in the presence of different phenolic compounds implies that phenolic contaminants may play a role in PAHs degradation. After 240 h, organic contaminants were removed from BRW in the following order: phenol >2,4-dinitrophenol > 2-methyl-4,6-dinitrophenol > 2,3,4,6-tetrachlorophenol > acenaphthene > fluorine > phenanthrene > fluoranthene > pyrene > anthracene > chrysene > naphthalene > benzo(a)anthracene > benzo(a)pyrene > benzo(b)fluoranthene > pentachlorophenol > indeno(1,2,3-cd)pyrene > benzo(j) fluoranthene > benzo[k]fluoranthène. The multiple contaminant remediation from the BRW by enzymatic method, clearly suggests that the laccase can be used as a bioremediation tool for the treatment of wastewater from various industries.

Mycoremediation of lignocellulosic biorefinery sludge: A reinvigorating approach for organic contaminants remediation with simultaneous production of lignocellulolytic enzyme cocktail.

This research work aims to valorize lignocellulosic biorefinery sludge with genetically engineered Trichoderma atroviride for simultaneous removal of organic contaminants, fermentation inhibitors, and lignocellulolytic enzyme cocktail production. Upon analysis, three phenolic compounds (42.6 ± 3.6 µg/g), two polycyclic aromatic hydrocarbons (0.42 ± 0.06 µg/g) and five fermentation inhibitors (2.5 ± 0.3 mg/g) were detected in the sludge. Bioaugmentation of sludge with 72 h-old T. atroviride (5%) results in the production of cellulase (21 U/g), xylanase (84 U/g), laccase (20 U/g), lignin peroxidase (14 U/g) and aryl alcohol oxidase (116 U/g), along with the concomitant removal of organic contaminants (phenol, 2, 4-dinitrophenol, pentchlorophenol, phenanthrene, benzo(a)pyrene) and fermentation inhibitors (furfural, 5-hydroxymethylfurfural, levulinic acid, ferulic acid, and catechol). Subsequently, the enrichment of sludge with nutrients and rhamnolipids enhanced the enzyme production by 5-6-fold and resulted in the removal of 85-95% of organic contaminants and fermentation inhibitors, which constitutes an eco-friendly process.

Surfactant-aided mycoremediation of soil contaminated with polycyclic aromatic hydrocarbons.

Remediation of persistent polycyclic aromatic hydrocarbons (PAHs) contaminated soil has become a major challenge in recent years. Further, conventional application of bioaugmentation strategies for PAHs remediation require continuous supply of microbial specific nutrients, which makes these processes less feasible. Hence, the present study focused on PAHs remediation using surfactants along with wood assisted fungal system in a microcosm set up. In this study, in absence of surfactants, a saturation in PAHs degradation was noted in bioaugmentation with wood assisted fungal system (BAW) with 61 ± 1.25% degradation, followed by bioaugmentation with free fungi system (BAF) (54 ± 0.46%). However, with addition of 1500 mg/L of surface-active compounds (SAC), a maximum PAHs degradation in BAW (100%) and BAF (86 ± 1.30%) strategies were noted on 21st day. Irrespective of the strategies, presence of SAC and rhamnolipids enhanced PAHs degradation by increasing the enzymes production in Trametes hirsuta when compared to Triton x-100 and sodium dodecyl sulphate (SDS). Among the detected PAHs, 100% degradation within 17 days was noted for naphthalene and acenaphthene in SAC-supplemented BAW system. Further, ecotoxicity analysis established showed the LC50 of sediment soil at 26.5 ± 0.24%, which was reduced by an average of 71% after soil remediation. Hence, the current microcosm system proved that the application of SAC with BAW enhanced the PAHs remediation rate, which supports its application in real time soil remediation.

Insolubilization of Tramates versicolor laccase as cross-linked enzyme aggregates for the remediation of trace organic contaminants from municipal wastewater.

The novelty of this study deals with the biocatalytic treatment of trace organic contaminants (TrOCs) from municipal wastewater by insolubilized laccase. Laccase from Trametes versicolor was aggregated by three-phase partitioning technique followed by cross-linking with glutaraldehyde to produce insolubilized laccase as cross-linked enzyme aggregates (CLEAs). The optimal conditions for CLEAs preparation include ammonium sulphate concentration of 83% (w/v), crude to t-butanol ratio of 1.00: 1.05 (v/v), pH 5.3, and glutaraldehyde concentration of 20 mM obtained via statistical design. The efficiency of insolubilization of the CLEAs laccase based on the kcat/km ratio was approximately 4.8-fold greater than that of free laccase. The developed CLEAs showed greater resistance to product inhibition mediated by ABTS than the free enzyme and exhibited excellent catalytic activity even after the tenth successive cycle. Further, free laccase and the synthesized CLEAs laccase were utilized to treat five analgesics, two NSAIDS, three antibiotics, two antilipemics, and three pesticides in the municipal wastewater. Under the batch process with operating conditions of pH 7.0 and 20 °C, 1000 U/L of CLEAs, laccase removed 11 TrOCs in the range of about 20-99%. However, the inactivated CLEAs only adsorbed 2-25% of TrOCs. It was observed that acetaminophen, mefenamic acid, trimethoprim, and metolachlor depicted almost complete removal with CLEAs laccase. The performance of CLEAs laccase in a perfusion basket reactor was tested for the removal of TrOCs from municipal wastewater.

Fabrication of highly permeable and anti-fouling performance of Poly(ether ether sulfone) nanofiltration membranes modified with zinc oxide nanoparticles.

Membrane fouling is one of the challenging bottleneck problems in waste water treatment by membrane process. The present study constructed a nanofiltration membrane based on the zinc oxide nanoparticle (n-ZnO) integrated Poly(ether ether sulfone) (PEES) membranes. The developed membranes were characterized by X-ray diffraction (XRD), attenuated total reflectance - fourier transform infrared spectroscopy (AT-FTIR), atomic force microscopy (AFM) and scanning electron microscope (SEM) coupled with energy dispersive X-ray (EDX) analysis. Pure water flux, contact angle, molecular weight cut-off, mean pore size and porosity were determined to investigate the influence of n-ZnO on the properties of the membranes. The characterization showed asymmetric configuration of membranes after n-ZnO incorporation. This incorporation also enhanced the hydrophilicity of PEES membrane. The fouling-resistant potential of the membranes was investigated by the model foulant humic acid (HA) and an enhanced anti-fouling irreversible property with a corresponding flux recovery rate of 92.43 % was noted for the prepared membrane. The rejection performance and permeability of HA was 98.03 % and 166.73 L m-2 h-1, respectively, owing to the hydrophilic nature of ZnO particles. Further, modified PEES membrane exhibited superior separation performance for monovalent and divalent anions. PEES/n-ZnO hybrid membrane assisted nanofiltration is an effective process for the improvement of membrane performance and anti-fouling property, demonstrating its immense use in water reclamation.

Understanding the factors affecting adsorption of pharmaceuticals on different adsorbents - A critical literature update.

Remediation of emerging pharmaceutically active compounds (PhACs) as micropollutants in wastewater is of foremost importance as they can cause extremely detrimental effects on life upon bioaccumulation and generation of drug-resistance microorganisms. Presently used physicochemical treatments, such as electrochemical oxidation, nanofiltration and reverse osmosis, are not feasible owing to high operating costs, incomplete removal of contaminants along with toxic by-products formation. Adsorption with the utilization of facile and efficient nanoparticulate adsorbents having distinctive properties of high surface area, excellent adsorption capacity, ability to undergo surface engineering and good regeneration displays great potential in this aspect along with the incorporation of nanotechnology for effective treatment. The application of such nanosorbents provides optimal performance under a wide range of physicochemical conditions, decreased secondary pollution with reduced mechanical stress along with excellent organic compound sequestration capacity, which in turn improves the quality of potable water in a sustainable way compared to current treatments. The present review intends to consolidate the range of factors that affect the process of adsorption of different PhACs on to various nanosorbents and also highlights the adsorption mechanism aiding in the retrieval.

Effect of alkaline treatment on the removal of contaminants of emerging concern from municipal biosolids: Modelling and optimization of process parameters using RSM and ANN coupled GA.

The current study aimed in enhancing the efficiency of alkaline treatment for CECs remediation in biosolids through the application of RSM and ANN. Due to the seasonal variation of CECs in biosolids, a complete CECs profile over a period of three years were performed. Out of 64 targeted CECs, 13 PhACs (70.1 µg/kg) and 10 pesticides (57.2 µg/kg) were detected in biosolids. In order to enhance the remediation efficiency of CECs by alkaline treatment, process parameters - pH (9.0-13.0), time (3.0-12.0 h) and biosolids age (1-28 days) were optimized by statistical modelling. Using Box-Behnken design, experiments were designed and the resultant data was employed as input for model building using RSM and ANN. The developed mathematical model for alkaline treatment of biosolids using ANN predicted CECs removal with 3.2-fold lower MSE and exhibited high regression coefficient (R2 > 0.99) than the conventional RSM model. Further, the multiparameter model was optimized for achieving maximum of 95.7 % CECs removal using ANN-GA. On analyzing the acute toxicity of alkaline treated residual biosolids under the optimized conditions, a reduction in LC50 by an average of 2.1-fold than initial biosolids was observed. This study not only established the application of statistical modelling in the development of an efficient remediation strategy for biosolids, which can be further applied for large-scale remediation process, but also proved the reliability and efficiency of ANN-GA.

Development of a sustainable route for the production of high-fructose syrup from the polyfructan inulin.

The authors used mesoporous silica microspheres as a support for the immobilization of inulinase from Aspergillus brasiliensis MTCC 1344 by the process of cross-linking. Under optimized operating conditions of pH 6.0, particle/enzyme ratio of 2.0:1.0 and glutaraldehyde concentration of 7 mM, a maximum immobilization yield of 90.7% was obtained after a cross-linking time of 12.25 h. Subsequently, the cross-linked inulinase was utilized for the hydrolysis of 5% inulin, and a maximum fructose concentration of 31.7 g/L was achieved under the optimum conditions of pH 6.0 and temperature 60°C in 3 h. Furthermore, on performing reusability studies during inulin hydrolysis, it was observed that the immobilized inulinase could be reused up to 10 subsequent cycles of hydrolysis, thus providing a facile and commercially attractive process of high-fructose syrup production.

Application of statistical modeling for the production of highly pure rhamnolipids using magnetic biocatalysts: Evaluating its efficiency as a bioremediation agent.

In the present study, highly pure rhamnolipids (RLs) was produced using biocatalysts immobilized on amino-functionalized chitosan coated magnetic nanoparticles. Upon immobilizing naringinase and Candida antarctica lipase B (CaLB) under the optimized conditions, an enhanced operational stability with biocatalytic loads of 935 ± 2.4 U/g (naringinase) and 825 ± 4.1 U/g (CaLB) were achieved. Subsequently, the immobilized biocatalysts were utilized sequentially in a two-step RLs synthesis process. The key parameters involved in RLs production were optimized using artificial neural network (ANN) coupled genetic algorithm (GA) and were compared with composite central design (CCD). On validating the efficiency of both models, mean square errors of 1.58% (CCD) and 1.04% (ANN) were obtained. Optimization of parameters by ANN-GA resulted in 1.2-fold increase in experimental RLs yield (80.53%), which was 1.05-fold higher when compared to CCD model. Further, to establish the efficiency of RLs as a bioremediation agent, it was utilized as washing agent. It was observed that at a soil to RLs volume of 1:05, RLs concentration of 0.4 mg/mL, a 95.35 ± 1.33% removal of Total Petroleum Hydrocarbons (TPHs) was obtained at 35 â„ƒ and 160 rpm in 75 min. Thus, this strategy provides an efficient biocatalytic toolbox for RLs synthesis, which can be effectively used as a bioremediation agent.

Preparation of highly diffusible porous cross-linked lipase B from Candida antarctica conjugates: Advances in mass transfer and application in transesterification of 5-Hydroxymethylfurfural.

The present work pronounces the three phase partitioning (TPP)-facilitated preparation of porous cross-linked Candida antarctica lipase B (CaLB) aggregates (pCLEAs) for 5-Hydroxymethylfurfural (HMF) esters synthesis. CLEAs and pCLEAs of CaLB were prepared with eupergit as the support under the optimized conditions of pH 8.0, eupergit/protein ratio of 3.0:1.0, 50 mM cross-linker concentration and 3.3 mg/mL BSA concentration in 4 h. The optimum starch concentration for pCLEAs was 0.20%, m/v. The maximum biocatalytic load was 650 U/g (CLEAs) and 721 U/g (pCLEAs), and the immobilized biocatalysts were stable over a pH range of 6.0-9.0 and temperature range of (40-60)°C. The BET surface area of CLEAs and pCLEAs were 21.3 and 29.1 m2/g, respectively, and the catalytic efficiency of pCLEAs was 2.2-fold higher than that of CLEAs. Subsequently, the pCLEAs of CaLB were utilized for the manufacturing of industrially significant HMF esters. Under the optimized transesterification conditions, HMF conversion with pCLEAs CaLB was 1.41- and 1.25-fold higher than with free and CLEAs CaLB, respectively. The pCLEAs were reused upto 8 consecutive transesterification cycles and the produced HMF esters reduced the surface tension of water from 72 mN/m to 32.6 mN/m, proving its potential application as surface-active compounds.

Performance study on adsorptive removal of acetaminophen from wastewater using silica microspheres: Kinetic and isotherm studies.

Owing to the global industrialization, a new generation of pharmaceutical pollutants with high toxicity and persistency have been detected. In the present study, silica microspheres, a promising adsorbent has been employed to investigate the extent of removal of prevalent therapeutic acetaminophen, an emerging micropollutant, from wastewater in isolated batch experiments. The BET surface area of the adsorbent was 105.46 m2/g with a pore size of 15 nm. Characterization of adsorbent by scanning electron microscopy analysis revealed the microparticulate nature with a 15 ± 5 µm particle size. Optimization of reaction parameters for enhanced assimilative removal of pollutants was performed and the highest adsorption of 96.7% of acetaminophen with an adsorption capacity of 89.0 mg/g was observed upon contact time of only 30 min. Mild process conditions of pH 5.0, 20 ppm of acetaminophen, temperature of 303 K, and 100 ppm sorbent concentration further aided in the removal process. Obtained data were best corresponded with the Freundlich isotherm (n = 2.685), indicating highly favorable adsorption. Acetaminophen adsorption kinetics obeyed the pseudo second order and feasible energetic changes were yielded through the thermodynamic analysis. Silica microspheres recovery carried out through a single-step desorption process had a 99.14% retrieval ability.

Amino-functionalised mesoporous silica microspheres for immobilisation of Candida antarctica lipase B - application towards greener production of 2,5-furandicarboxylic acid.

In the present study, amino-functionalised mesoporous silica microspheres were utilised as support for the covalent immobilisation of Candida antarctica lipase B (CaLB) for the subsequent production of 2,5-furandicarboxylic acid (FDCA) from 2,5-diformylfuran (DFF). Under the optimised operating conditions of pH 6.5, particle/enzyme ratio of 1.25:1.0 and glutaraldehyde concentration of 4 mM, a maximum CaLB immobilisation yield of 82.4% on silica microspheres was obtained in 12.25 h. The immobilised CaLB was used for the synthesis of alkyl esters, which were utilised along with hydrogen peroxide for FDCA synthesis. The biocatalytic conversion of 30 mM DFF dictated a 77-79% FDCA in 48 h at 30°C; where the turnover number and turnover frequency of immobilised CaLB were 6220.73 mol mol-1 and 129.59 h-1, respectively, for ethyl acetate, against 6297.65 mol mol-1 and 131.2 h-1, respectively, for ethyl butyrate. Upon examining the operational stability, the immobilised CaLB exhibited high stability till five cycles of FDCA production.

Development of a magnetically separable co-immobilized laccase and versatile peroxidase system for the conversion of lignocellulosic biomass to vanillin.

Lignin obtained from renewable biomass is a potential feedstock for the synthesis of various value-added chemicals through efficient biocatalytic routes. The ligninolytic enzymes-assisted depolymerization of lignin to vanillin constitutes the most commercially attractive and promising approach in green chemistry as vanillin constitutes the second most prevalent flavoring agent. Thus, in the present work, immobilized laccase and versatile peroxidase, and further, a co-immobilized laccase and versatile peroxidase system on magnetic silica microspheres (MSMS) were developed to generate a robust biocatalytic system that mediates the depolymerization of lignin obtained from Casuarina equisetifolia biomass. The depolymerization of lignin by free and immobilized laccase showed a vanillin yield of 24.8% and 23%, respectively, at pH 4.0 in 6 h at 30°C against a vanillin yield of 20% and 21.7% with the free and immobilized versatile peroxidase, respectively, at pH 5.0°C and 50°C. Comparatively, the system with the co-immobilized laccase and versatile peroxidase exhibited a 1-fold and 1.2-fold higher vanillin yield than the free and immobilized laccase system, respectively. On comparing with the versatile peroxidase system, the co-immobilized biocatalytic system displayed 1.3-fold and 1.2-fold increased vanillin yield than the free and immobilized versatile peroxidase system, respectively, at a pH of 6.0 in 6 h at 30°C with an enzyme concentration of 1 U/ml. The reusability studies of the co-immobilized biocatalytic system exhibited that both the enzymes retained up to 40% of its activity till sixth cycle. Implications: The waste biomass of Casuarina equisetifolia is widely available around the coastal regions of India which does not have any agricultural or industrial applications. The present work exploits the lignocellulosic content of the Casuarina biomass to extract the lignin, which provides a renewable alternative for the production of the commercially high-valued compound, vanillin. This work also integrates a co-immobilized biocatalytic process comprising of laccase and versatile peroxidase leading to an environmentally benign enzymatic process for the depolymerization of lignin to vanillin.

Rhamnolipid-assisted mycoremediation of polycyclic aromatic hydrocarbons by Trametes hirsuta coupled with enhanced ligninolytic enzyme production.

The present study deals with the development of a wood assisted fungal system (WAFS) from wood chips using Trametes hirsuta to remove polycyclic aromatic hydrocarbons (PAHs) in BRW. The WAFS exhibited a 1.4-fold higher ligninolytic enzyme production than free fungi in the effluent. Further, to understand PAHs bioremediation by T. hirsuta, biodegradation along with biosorption were studied in model PAHs, phenanthrene (Phe) and benzo (a) pyrene (BaP), in the presence of synthesized rhamnolipids. The WAFS mineralized up to an average of 91.26% Phe and 87.72 % BaP along with biosorption of 12.35% Phe and 18.36 % BaP within 12 days. Thus, the addition of rhamnolipids showed 1.2-fold enhanced biodegradation. However, rhamnolipid concentrations beyond 50 ppm reduced the degradation efficiency of WAFS. Moreover, the degradation capability of total aromatic hydrocarbon (TAH) in biorefinery wastewater by WAFS is 1.8-fold higher than that of free fungi, which confirms the effectiveness of the system. Implications: Simultaneous application of white-rot fungus along with surfactant into a pollutant environment affects the microenvironment of the fungus and reduces the production of their degradative enzymes. In addition, the requirement of periodical supplement of external nutrient in the real-time matrix for the growth of white rot fungi may trigger competitive growth of indigenous microorganisms. Considering this glitch, the current work utilizes the carpenter waste for the strategical develop a wood assisted fungal system to protect the microenvironment of the fungi in the presence of rhamnolipids and contribute to their survival in real time matrix, with enhanced PAHs degradation efficiency.

Simultaneous pretreatment and saccharification process for fermentable sugars production from Casuarina equisetifolia biomass using transgenic Trichoderma atroviride.

With the increase in the cognizance toward the wide and abundant lignocellulosic biomass, a great interest has been garnered toward the production of value-added products from the biomass. Hence, by capitalizing the Casuarina equisetifolia biomass, the current work developed a simultaneous pre-treatment and saccharification (SPS) process using transgenic Trichoderma atroviride. The ability of T. atroviride to produce lignolytic and cellulolytic enzymes was enhanced by optimizing key process parameters. Under the optimized conditions, a maximum of 1245.6 U/kg of cellulase and 1203.36 U/kg of xylanase, 183.2 U/kg of laccase along with 392.36 g/kg of fermentable sugars were obtained. On comparing with acid and alkaline pre-treatment methods, the T. atroviride -mediated SPS process exhibited trace formation of fermentative inhibitors, which resulted in a minimal inhibition of Escherichia coli. Overall, the current work implements the biorefinery concept on Casuarina equisetifolia biomass by advocating circular economy. Implications: Valorization of lignocellulosic waste biomass into value added compound and as biofuel is considered as a promising alternative resource, owing to its availability and low production cost. However, the presence of chemically resistant lignin demands an intensive treatment process, which sometimes leads to the formation of fermentative inhibitors. Casuarina equisetifolia is a deciduous commercial plant, and an average of 125 tonnes/hector of waste is generated annually in India. By considering the demerit of delignification and the wide availability of Casuarina equisetifolia biomass (CB), the current work aimed at the development of a single-pot simultaneous pre-treatment and saccharification (SPS) of CB by transgenic Trichoderma atroviride.

Effect of soil organic matter (SOM) on the degradation of polycyclic aromatic hydrocarbons using Pleurotus dryinus IBB 903-A microcosm study.

Bioremediation of polycyclic aromatic hydrocarbons (PAHs) in soil matrix is often arbitrated by the presence of soil organic matter (SOM). The present study focuses on determining the effect of the soil organic content on the mycoremediation of two model PAHs, phenanthrene (Phe) and benzo(a) pyrene (BaP) through microcosm studies. On comparing various microcosm strategies, a maximum degradation of Phe (99%) and BaP (48.5%) in soil bioaugmented with Pleurotus dryinus IBB 903, followed by, biostimulation with the degradation of Phe (89.9%) and BaP (24.8%) were noted. On relating the degradation pattern with lignolytic enzyme cocktail production, a laccase activity of 108 U/Kg at day 21, aryl alcohol oxidase (411 U/Kg) and manganese peroxidase (52.2 U/Kg) at day 14 along with lignin peroxidase (481 U/Kg) at day 21 were noted in fungal augmented soils, which were comparatively higher than levels observed in the bio-stimulation. Investigating the impact of different concentration of SOM (3-12%), a maximum remediation of Phe by 100% at 9% SOM in days 28 and 58.19% for BaP at 12% SOM, respectively was exhibited. Further, the biosorption effect of PAHs in abiotic condition showed a positive correlation with the increase in SOM, with a maximum adsorption of 3.78% Phe, and 6.93% BaP. The results support that the nominal adsorption ability of SOM, and helps in enhancing the microbial growth, thereby improving their degradation potentials, when less than 6% of SOM was utilized. Overall, this work establishes the critical role of organic matter in the soil with reference by simultaneous stimulation and degradation capability in complete PAHs remediation.

A comparative study on the chemo-enzymatic upgrading of renewable biomass to 5-Hydroxymethylfurfural.

5-hydroxymethylfurfural (HMF) obtained from renewable biomass-derived carbohydrates is a potential sustainable substitute to petroleum-based building blocks. In the present work, we constituted a comparative study on the production of HMF from two widely available real biomasses in India- Agave americana and Casuarina equisetifolia. In the initial hydrolysis studies for the production of reducing sugars, 649.5 mg/g of fructose was obtained from the hydrolysis of 5% (w/v) A. americana biomass by the enzyme inulinase in 3 h at 50°C. Similarly, upon hydrolysis of 15% (w/v) C. equisetifolia biomass by the lignocellulolytic enzymes (laccase, cellulase and xylanase) from Trichoderma atroviride, 456.65 mg/g of reducing sugars was released in 24 h at 30°C. Subsequently, the dehydration of the obtained reducing sugars to HMF was achieved with titanium dioxide as the catalyst. The dehydration of A. americana-derived fructose at 140°C led to a maximum HMF yield of 92.6% in 15 min with 10% catalyst load. Contrarily, upon optimizing the process parameters for dehydration of C. equisetifolia derived reducing sugars, the maximum HMF yield of 85.7% was obtained at 110°C in 25 min with a TiO2 concentration of 10%. This study reports for the first time the utilization of C. equisetifolia biomass for HMF production and thus, by utilizing these inexpensive, abundantly available and highly functionalized polysaccharides, a strategical approach can be developed for the production of fine chemicals, eliminating the need of fossil-based chemicals. Implications: The catalytic upgrading of lignocellulosic biomass into high-valued platform chemicals like 5-Hydroxymethylfurfural (HMF) implies an extremely significant challenge to the attempts of establishing a green economy. Casuarina equisetifolia and Agave americana represents a sustainable feedstock for the production of HMF through catalytic integration. The present work describes a two-step reaction process where the initial depolymerization step comprises of an enzymatic hydrolysis followed by a chemical-catalyst mediated dehydration process. The utilization of a biocatalytic approach followed by mild chemical catalyst eliminates the need of hazardous chemical conversion processes. Thus, the HMF produced via sustainable can bridge the gap between carbohydrate chemistry and petroleum-based industrial chemistry because of the wide range of chemical intermediates and end-products that can be derived from this compound.