Enhancing Rice Straw Fibers for Pulp Films Using DES and <i>Streptomyces rochei</i> Synergy

Long-time fermentation has always been one of the reasons restricting the development of straw biological pulping. This study aimed to develop a novel straw pulp film with shortened solid-state fermentation time with less than 20% mass loss rate by bio-pulping synergistic treatment of straw fibers with deep eutectic solvent (DES) and Streptomyces rochei (S. rochei). Results illustrated that at 3% S. rochei concentration with 7-day fermentation, both cellulose and hemicellulose enzyme activities of the treated rice straw fiber reached peak values with a fiber mass loss rate of 17.01%. Microstructural morphology revealed that S. rochei colonization initiated on straw surfaces and progressively penetrated internal structures, resulting in surface loosening and distinct disruption of cell wall tissues within vascular bundles in transverse sections. The treated rice straw strip indicated a maximum tensile strength of 46.22 MPa for (Bacteria) BA 3% at day 7, attributed to optimized synergistic effects of microfibril angle (MFA) and cellulose/hemicellulose relative content ratio. The modified straw pulp film exhibited significant enhancement in the tensile index (44.9% increase), burst index (10.3% increase), and tear index (60% increase) compared to untreated groups. This work demonstrated the important role of DES and S. rochei bio-pulping synergistic treatment in improving rice straw pulp performance, suggesting an eco-friendly, novel, and efficient biomass pretreatment technology for potential application prospects in sustainable agricultural mulching materials.