Deterioration-Associated Fungi in Silicone Rubber-Sealed Ancient Ivory at Jinsha Site

Ancient ivory artifacts are susceptible to deterioration due to environmental factors. Ivory artifacts excavated from the Jinsha site in Chengdu, China, were sealed in silicone rubber for protection. Over time, discoloration of the silicone rubber and fuzzy substance development on the silicone-sealed ivory affected its preservation. Microscopy revealed mycelia in both the silicone rubber and ivory. High-throughput sequencing indicated that the colonizing fungi were mostly in the genus Trichoderma . Cultivation and genome-based analyses of Trichoderma rifaii JS-6 isolated from the ivory revealed that the strain can grow under low-oxygen and oligotrophic conditions. T. rifaii JS-6 produced pigments and organic acids leading to discoloration of the ivory and threatening its structural integrity. Growth of T. rifaii JS-6 on ivory was most effectively prevented by physically removing the hyphae, followed by spraying with 0.01% 4,5-dichloro-2-octyl-isothiazolone. The results provide scientific basis for the conservation of ancient ivory and similar artifacts.