# Uncovering Microbial Diversity and Community Structure of Black Spots Residing in Tomb Mural Painting

## TL;DR

This study explores the microbial communities in black spots on ancient tomb mural paintings and finds specific fungi linked to contamination, affecting both heritage conservation and public health.

## Contribution

The study identifies Gliomastix and Ochroconis as key genera in black spot contamination and reveals distinct microbial assembly processes in these areas.

## Key findings

- Gliomastix and Ochroconis were highly abundant in black spots but rare in air and uncontaminated areas.
- Black spots showed lower network complexity and different microbial assembly processes compared to other areas.
- Microbial functions in black spots include nitrogen cycling and pathogen activity, posing risks to cultural relics and health.

## Abstract

Microbes colonizing cultural artifacts are a ubiquitous phenomenon which may occur during burial, post-excavation, and storage periods, thereby seriously affecting sustainable heritage conservation. In this study, high-throughput sequencing technology was applied to analyze the microbial community structure in ancient mural paintings and the surrounding air, as well as to identify the most characteristic taxa causing black spot contamination. The results showed that members of the genera Gliomastix and Ochroconis were highly abundant in black-spots-contaminated areas and rarely detected in the air and uncontaminated mural paintings. Air samples of the two tombs showed no significant difference in Chao1 and Shannon indices, whereas statistically significant differences were observed compared to those samples collected from black spots. The taxonomic diversity of the microbial community in the soil-covered mural paintings and air exhibited similar structures at the genus level. Moreover, when compared to other areas of the two tombs, the samples from black spots differed not only in microbial community composition but also in microbial assembly processes and the co-occurrence patterns, such as much less network complexity in the black spots area. Functional predictions uncover the presence of microbial functional profiles involved in nitrogen cycling, organic matter degradation, and animal and human pathogens, representing a potential threat to cultural relics and public health. These results advance our understanding of the impacts of archeological excavations on the microbial community variation in tomb mural paintings.