Mechanism and Control of Black Spot Deterioration on Lacquered Architectural Components of Dajue Temple

Dajue Temple, a representative ancient architectural heritage in North China, houses numerous lacquered wooden components of exceptional historical and artistic value. Despite their significance, this study is the first to investigate the severe dark discoloration and black spotting afflicting these lacquer surfaces—damage triggered by prolonged environmental exposure that endangers structural integrity and long-term conservation. To address this unstudied threat, we confirmed the microbial origin of black spots using ATP bioluminescence assays, then characterized microbial communities via culture-dependent methods and ITS sequencing—identifying Cladosporium spp. as the dominant biodeterio-gen driving lacquer deterioration. Functional assays on carboxymethylcellulose (CMC) and guaiacol-amended potato dextrose agar (PDA) media verified the wood-degrading potential of isolated Cladosporium spp. Antifungal susceptibility screening against ten agents demonstrates that thymol and clove essential oils achieved significant efficacy at 200 mg/mL, while nano silver gel also provided durable suppression. We proposed targeted, relic‑friendly microbial control strategies tailored for ancient lacquered wooden components. These findings provided scientific guidance for the sustainable conservation and restoration of lacquered architectural elements in historic temples and comparable cultural heritage sites. In future work, environmental monitoring should be involved, which will help to clarify microbe–environment interactions and enable early warning of biodeterioration risks.