Extracellular Biopolymer Production by Acrostalagmus luteoalbusfrom Agro-Industrial Wastes: Toward Sustainable Material Development

Introduction: Plastic pollution has intensified the search for biodegradable alternatives from renewable sources. Microbial fermentation using agro-industrial residues offers a sustainable strategy for producing biopolymers with reduced environmental impact. This study evaluated the production and characterization of an extracellular biopolymer synthesized by Acrostalagmus luteoalbus using low-cost carbon substrates. Methodology: Fermentations were carried out for eleven weeks using pulp with tejocote peel, fruit peels, and sucrose-based media . Biopolymer yields were quantified, followed by physicochemical characterization , elemental analysis (CHNS) , and thermal assessments (TGA and DSC) to evaluate structural and functional properties. Results: All substrates supported biopolymer synthesis, with pulp with tejocote peel yielding the highest production (~17.10% ± 1.29 at week nine), indicating a strong influence of substrate composition and incubation time . The biopolymer was dark brown, brittle, insoluble in polar and non-polar solvents, and thermally stable , with degradation occurring above 250 °C . CHNS analysis showed a carbon-rich, low-nitrogen composition , while TGA and DSC revealed multi-step degradation and no melting transitions , suggesting a heterogeneous, cross-linked polymeric network . Discussion: The extracellular nature simplifies recovery compared to intracellular polymers and combined with thermal stability and solvent resistance , supports applications in biodegradable packaging, coatings, and biomedical materials. Agro-industrial residues represent a cost-effective and sustainable carbon source for biopolymer production. Conclusions: Acrostalagmus luteoalbus offers a promising platform for producing biodegradable, thermally stable biopolymers from agro-industrial wastes, contributing to circular economy strategies and industrial-scale sustainability efforts.