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Microbial biomineralization is explored as a strategy for improving the thermal stability of symbiotic cultures of bacteria and yeast (SCOBY) cellulose aerogels. Cellulose pellicles were grown in kombucha tea and subsequently biomineralized with Sporosarcina pasteurii (S. pasteurii). The samples were exposed to one, two, or three cycles of ureolytic biomineralization. The microstructure and material properties of biomineralized samples were compared to experimental controls, which included a non‐biomineralized cellulose aerogel sample and an abiotic cellulose aerogel sample that was exposed to the biomineralization treatment without the addition of S. pasteurii. Results indicate that significant biomineralization (up to 38% CaCO3 by mass) occurred in the biomineralized SCOBY cellulose aerogels. Multiple biomineralization cycles enhance biomineralization of the sample surface and interior. Thermal conductivities of resultant aerogels measured ≈0.043–0.057 Wm−1 K−1 for all samples, indicating that biomineralization did not negatively affect the thermal conductivity of the SCOBY cellulose aerogels. Results further illustrate that biomineralization improved the thermal stability and flame resistance of SCOBY cellulose aerogels compared to experimental controls. Low thermal conductivity, improved thermal stability, and higher flame resistance of biomineralized SCOBY cellulose aerogels together indicate that thermally stable insulation materials can be produced exclusively from biological organisms.

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