Wood is a sustainable carbon-storage material that is widely used in construction and packaging. However, its intrinsic flammability restricts its application. Existing flame-retardant modifications either rely on toxic chemicals or generate byproducts. In contrast, bioinspired microbially induced calcium carbonate precipitation offers a solution to this challenge. In this study, a facile method was developed for the in situ growth of Bacillus mucilaginosus (B.m.) on the wood porous structure. The B.m. solution exhibited a significantly low surface tension and a favorable wettability on wood surfaces. This is attributed to the extracellular polymeric substances secreted by the strain, which promote its deep penetration into wood structures without relying on vacuum or pressure-assisted conditions. During ambient drying, B.m. utilizes carbonic anhydrase to capture atmospheric CO2, inducing CaCO3 deposition in cell lumens of wood and formed mineralized wood. Morphological and chemical characterizations confirmed the formation of well-crystallized CaCO3 without altering the wood appearance. The B.m.-treated wood has a higher residual weight, delayed thermal decomposition, reduced heat release, and faster self-extinguishing ability, achieving enhanced flame retardancy. This waste-free and energy-efficient process can achieve CO2 sequestration, aligns with zero-waste city goals, and has broad potential in fire-safe wood applications.
Tu et al. (Mon,) studied this question.