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

Enhanced production of turanose using a mutant amylosucrase from Bifidobacterium thermophilum immobilized on silica carriers

Turanose (α-d-glucopyranosyl-(1→3)-α-d-fructose) is a rare disaccharide that is a potential low-calorigenic sweetener. This novel sucrose isomer has been efficiently synthesized by the amylosucrase from Bifidobacterium thermophilum (BtAS). In this study, we aimed to enhance turanose biosynthesis by designing a BtAS variant (BtAS-G374S) with improved thermal stability. The BtAS variant was immobilized on porosity-controlled silica carrier, and its enzymatic properties were thoroughly investigated. Using response surface methodology with central composite design, optimal immobilization conditions were determined to significantly boost the biosynthetic efficiency. The BtAS-G374S showed 1.6-fold higher specific activity (2.2 U/mg) than the wild-type enzyme (1.4 U/mg). Additionally, the turanose production yield of BtAS-G374S was significantly enhanced, reaching 65 %, compared to 25 % for the wild-type enzyme when reacting with 2 M sucrose. Immobilization of BtAS-G374S was optimized on controlled porosity carrier (CPC) silica carrier using Response Surface Methodology, achieving an enzyme activity of 7.89 U and an immobilization efficiency of 68.98 % under optimal conditions. Immobilization of BtAS-G374S on CPC silica carriers enhanced its pH and thermal stability. The immobilized enzyme showed a half-life of 50.23 h at 55 °C and retained 68 % of its initial biosynthetic yield after 10 reuses. These properties suggest its potential for efficient industrial turanose production.

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.

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.