Bioactive living building materials for heavy metal remediation via microbial co-culture

Leptolyngbya boryana GGD, a filamentous cyanobacterium, serves as the biological core of living building materials (LBMs). However, its rapid loss of viability under Cd²⁺ stress limits its utility in contaminated environments. To enhance the resilience of this strain, the Cd²⁺-tolerant Lysinibacillus sp. HMR (defined here as heavy metal resistance) is selected from among 31 environmental isolates for co-cultivation with the GGD strain. The HMR strain promotes the accumulation of extracellular matrix structures around the GGD strain cell surface, thereby significantly enhancing its Cd²⁺ tolerance. Co-cultivation with the HMR strain also facilitates electrostatic interactions with Cd²⁺ and promotes CaCO₃ precipitation. These synergistic interactions strengthen the co-culture-based LBMs by promoting robust mineralization and significantly enhancing Cd²⁺ adsorption efficiency compared with the GGD strain monoculture. Here, we report that LBMs incorporating the GGD strain co-cultured with the Cd²⁺-tolerant HMR strain represent a promising platform for sustainable heavy metal bioremediation.