Presentation Information
[P02-287]A Fungal Oxidative Cocktail as a Tool to Tailor Kraft Lignin for Advanced Fibrous Materials
○Evanildo Francisco de Souza Jr.1, Leilivan R. Pimentel1, Guilherme C. de Andrade2, Isabella M. T. S. Santos1, Beatriz R. Penna2, Verônica Calado1, Nei Calado Pereira1 (1. Escola de Química, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 7 149, Bloco E, Rio de Janeiro, RJ, 21941-909, Brazil (Brazil), 2. Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Rio de Janeiro, RJ, 21941-902, Brazil (Brazil))
Keywords:
Kraft lignin,Oxidative enzyme cocktail,Electrospinning,Lignin valorization,Bio-based materials
Purpose
Kraft lignin is an abundant and renewable aromatic biopolymer with strong potential as a precursor for advanced carbon-based materials. However, its intrinsic heterogeneity, low molecular weight, and poor processability limit direct conversion into fibrous structures. Oxidative enzymes offer a promising strategy for tailoring lignin structure under mild conditions, yet multienzymatic systems for lignin valorization remain underexplored. This study investigated whether a crude oxidative enzymatic cocktail from Pycnoporus sanguineus could modify the macromolecular properties of Kraft lignin and improve its electrospinnability.
Method
An oxidative enzymatic cocktail (LADEBIO-Pys), enriched in laccase, lignin peroxidase, and manganese peroxidase, was produced by submerged fermentation and concentrated by tangential flow filtration (TFF). Kraft lignin was oxidized under controlled conditions and compared with treatments using commercial oxidative enzymes and defined enzyme mixtures. Structural, molecular, and thermal changes were evaluated by advanced polymer chromatography (APC), FTIR, ¹H NMR, TGA, and DSC. Electrospinning performance was assessed in the presence and absence of 1 wt% PEO. Enzymatic synergy was estimated from molecular weight shifts.
Results
The LADEBIO-Pys cocktail promoted pronounced lignin restructuring, with increases of approximately 150% in weight-average molecular weight (Mw) and 110% in polydispersity index (PDI), indicating extensive oxidative coupling and macromolecular reorganization. FTIR and ¹H NMR analyses revealed modifications in aromatic, methoxyl, hydroxyl, and carbonyl-associated regions, consistent with oxidative remodeling of lignin. Thermal analyses indicated increased glass transition temperature and altered degradation behavior, supporting structural reorganization of the polymer matrix. These changes directly translated into processability: untreated Kraft lignin remained unspinnable, whereas enzymatically modified lignin produced continuous electrospun fibers. The addition of 1 wt% PEO further improved fiber morphology, reducing the average diameter to ~0.23 µm and improving uniformity. Among the evaluated systems, LADEBIO-Pys showed performance comparable to purified Trametes versicolor laccase, while enzyme combinations showed synergistic effects, particularly in laccase–peroxidase combinations.
Consideration
The results indicate that oxidative enzyme synergy can function as a macromolecular engineering strategy for technical lignin. Rather than simply oxidizing isolated functional groups, the multienzymatic system promoted a controlled balance between radical generation, oxidative modification, and repolymerization, yielding a lignin architecture more compatible with fiber formation. In this context, electrospinnability emerged as a functional indicator of lignin processability and structural refinement.
Conclusion
This study demonstrates that crude fungal oxidative cocktails can effectively remodel Kraft lignin and expand its electrospinnability window without requiring enzyme purification or harsh chemical treatments. These findings support multienzymatic oxidative systems as scalable and sustainable tools for lignin valorization and the development of advanced bio-based materials.
Kraft lignin is an abundant and renewable aromatic biopolymer with strong potential as a precursor for advanced carbon-based materials. However, its intrinsic heterogeneity, low molecular weight, and poor processability limit direct conversion into fibrous structures. Oxidative enzymes offer a promising strategy for tailoring lignin structure under mild conditions, yet multienzymatic systems for lignin valorization remain underexplored. This study investigated whether a crude oxidative enzymatic cocktail from Pycnoporus sanguineus could modify the macromolecular properties of Kraft lignin and improve its electrospinnability.
Method
An oxidative enzymatic cocktail (LADEBIO-Pys), enriched in laccase, lignin peroxidase, and manganese peroxidase, was produced by submerged fermentation and concentrated by tangential flow filtration (TFF). Kraft lignin was oxidized under controlled conditions and compared with treatments using commercial oxidative enzymes and defined enzyme mixtures. Structural, molecular, and thermal changes were evaluated by advanced polymer chromatography (APC), FTIR, ¹H NMR, TGA, and DSC. Electrospinning performance was assessed in the presence and absence of 1 wt% PEO. Enzymatic synergy was estimated from molecular weight shifts.
Results
The LADEBIO-Pys cocktail promoted pronounced lignin restructuring, with increases of approximately 150% in weight-average molecular weight (Mw) and 110% in polydispersity index (PDI), indicating extensive oxidative coupling and macromolecular reorganization. FTIR and ¹H NMR analyses revealed modifications in aromatic, methoxyl, hydroxyl, and carbonyl-associated regions, consistent with oxidative remodeling of lignin. Thermal analyses indicated increased glass transition temperature and altered degradation behavior, supporting structural reorganization of the polymer matrix. These changes directly translated into processability: untreated Kraft lignin remained unspinnable, whereas enzymatically modified lignin produced continuous electrospun fibers. The addition of 1 wt% PEO further improved fiber morphology, reducing the average diameter to ~0.23 µm and improving uniformity. Among the evaluated systems, LADEBIO-Pys showed performance comparable to purified Trametes versicolor laccase, while enzyme combinations showed synergistic effects, particularly in laccase–peroxidase combinations.
Consideration
The results indicate that oxidative enzyme synergy can function as a macromolecular engineering strategy for technical lignin. Rather than simply oxidizing isolated functional groups, the multienzymatic system promoted a controlled balance between radical generation, oxidative modification, and repolymerization, yielding a lignin architecture more compatible with fiber formation. In this context, electrospinnability emerged as a functional indicator of lignin processability and structural refinement.
Conclusion
This study demonstrates that crude fungal oxidative cocktails can effectively remodel Kraft lignin and expand its electrospinnability window without requiring enzyme purification or harsh chemical treatments. These findings support multienzymatic oxidative systems as scalable and sustainable tools for lignin valorization and the development of advanced bio-based materials.
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