Lignin is the second most abundant terrestrial biopolymer and the largest natural reservoir of renewable aromatic carbon. Historically discarded or combusted as a low-value by-product of pulping and biorefining operations, lignin is increasingly recognised as a versatile feedstock capable of displacing petroleum-derived aromatics across materials, energy and environmental sectors. This review critically synthesises recent literature on lignin structure, extraction, valorisation and application, with particular attention to biomedical nanomaterials, food packaging, adhesives and polyurethane systems, carbon fibres, energy storage devices, water remediation, agriculture and biofuel production. The structural heterogeneity of lignin, arising from variable monolignol composition and interunit linkages, is examined as both the principal barrier to, and the source of functional richness underpinning, its valorisation. Extraction technologies, including kraft, sulfite, soda, organosolv and emerging ionic-liquid and deep-eutectic-solvent processes, are compared in terms of purity, yield, structural preservation and environmental burden. Applications are organised according to technology readiness and market relevance, and five summary tables consolidate quantitative findings on lignin sources, extraction performance, material applications, energy-related uses and environmental functions. The review further considers policy instruments and circular-bioeconomy frameworks that influence commercial uptake. Persistent obstacles, notably structural variability between feedstocks, incomplete standardisation of technical lignin grades and unresolved life-cycle trade-offs, are discussed alongside promising directions in catalytic depolymerisation and lignin-first biorefinery architectures. The evidence indicates that lignin valorisation is central to the transition towards a resource-efficient, low-carbon bioeconomy, provided that fractionation, standardisation and techno-economic barriers are addressed through coordinated research and policy action.
Latika Bhatia· Asian Journal of Research in...· 0 citations
Lignin is the most recalcitrant component of the plant cell wall, and its selective removal underpins numerous biotechnological processes ranging from second-generation biofuel production to animal feed upgrading and industrial effluent treatment. White-rot fungi remain the most efficient natural agents of lignin mineralisation, owing to a suite of extracellular oxidoreductases that include laccase, lignin peroxidase, manganese peroxidase and versatile peroxidase. Solid-state fermentation, a cultivation mode that mimics the natural substrate ecology of wood-decaying basidiomycetes, has become the preferred platform for harnessing this ligninolytic machinery at a scale relevant to industry. Yet a persistent obstacle to translating laboratory findings into predictable, scalable outcomes is the substantial variability in enzyme titres and delignification efficiency observed across fungal species, substrates, process configurations and reactor geometries. This review critically synthesises the literature on the ligninolytic performance of white-rot fungi during solid-state fermentation, with particular emphasis on the methods by which such performance can be extrapolated from small-scale screening experiments to pilot- and industrial-scale operation. The enzymatic basis of lignin depolymerisation is first outlined, followed by an appraisal of interspecific and intraspecific variability in enzyme yield. Substrate and process parameters that govern ligninolytic expression are then examined, before the review turns to the principal extrapolation strategies reported in the literature: statistical and response-surface methodologies, kinetic and mechanistic modelling, data-driven and machine-learning approaches, co-cultivation strategies, and bioreactor engineering approaches to scale-up. Applications enabled by reliable extrapolation, spanning biopulping, ruminant nutrition and bioremediation, are discussed alongside the persistent gaps that limit predictive confidence. The review concludes that although substantial empirical knowledge has accumulated regarding the ligninolytic capacities of individual white-rot species, the field still lacks a unifying quantitative framework capable of forecasting enzymatic performance across heterogeneous solid substrates and reactor formats, and it proposes that hybrid mechanistic–data-driven models represent the most promising avenue for closing this gap.
Latika Bhatia· Asian Plant Research Journal· 0 citations
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