Bio-Inspired CaCO ₃ Mineralization of Moso Bamboo for Improved Fungal Resistance and Fire Retardancy

Bioinspired strategies for enhancing the durability and functionality of natural materials offer a sustainable path toward high-performance biocomposites. In this study, Sporosarcina pasteurii was cultivated to biomineralize moso bamboo (Phyllostachys edulis) via microbially induced calcite precipitation (MICP). The bamboo blocks, before and after extraction, were subjected to biomineralization followed by leaching tests. Although extraction enhanced mineral uptake (4.4% for unextracted and 7.0% for extracted) before leaching, it did not significantly affect overall mass gain after leaching (∼3%), likely due to superficial mineral deposition. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the formation of calcium carbonate minerals, primarily as a mixture of calcite and vaterite. Optical microscopy, Scanning electron microscopy–Energy-dispersive spectroscopy (SEM-EDS), and X-ray microtomography (μCT) imaging revealed that mineral clusters were predominantly localized near the bamboo surface, forming globular CaCO3 with limited penetration into internal voids. The accelerated fungal durability was evaluated via a modified soil-block decay test, where biomineralized bamboo showed mass-loss values of ∼3% and 4% when exposed to Gloeophyllum trabeum (G.t.) and Trametes versicolor (T.v.), respectively, compared to controls (G.t.: ∼7%, T.v.: ∼8%). Postfungal mechanical testing indicated enhanced compressive modulus (+500 MPa) and compressive strength (+10 MPa) in biomineralized samples. Dynamic mechanical analysis further demonstrated improved viscoelastic properties, including elevated storage modulus (E′), loss modulus (E″), and Tan δ, indicating enhanced stiffness, energy dissipation, and thermal resilience, respectively. Fire and thermal performance, assessed through infrared imaging under combustion and thermogravimetric analysis (TGA), revealed shorter sustained flaming durations (<150 s), higher residual mass (+4.5%), and slower thermal degradation rates (∼8%/min) in biomineralized bamboo. Overall, this work demonstrates the potential of MICP-treated bamboo as a sustainable strategy to improve the durability and fire performance of biobased structural composites.