Table_2_Microbial Diversity in Moonmilk of Baeg-nyong Cave, Korean CZO.xlsx

The Baeg-nyong cave is a limestone cave which has been nominated as the first critical zone observatory (CZO) in South Korea. Moonmilk is a well-known speleothem composed of various carbonate minerals. To characterize moonmilk from the Baeg-nyong cave, we performed mineralogical analyses and applied high-throughput 16S rRNA gene sequencing to analyze the microbial communities, including bacteria and fungi, of dry and wet moonmilk samples. The results showed that the dry and wet moonmilk samples had different and atypical crystal structures, although they were predominantly composed of CaCO3. Furthermore, metagenomic data revealed that the dry and wet moonmilk samples collected from an oligotrophic environment had completely different bacterial communities when compared to the outside soil, and there was a difference in bacterial communities even between dry and wet moonmilk specimens. Fungal communities, however, did not differ significantly between dry and wet moonmilk samples. This study is the first metagenomic analysis of two different types of moonmilk with different physical properties and the first report on the microbial diversity of moonmilk from a cave in the first CZO in South Korea.

白牛洞乃一石灰岩洞穴，被誉为韩国首个关键带观测站（CZO）。月奶石，一种由多种碳酸盐矿物构成的著名洞穴沉积物，亦为研究之对象。为描绘白牛洞月奶石的特性，本研究进行了矿物学分析，并采用高通量16S rRNA基因测序技术，对干湿月奶石样本中的微生物群落进行了分析，包括细菌和真菌。研究结果表明，尽管干湿月奶石样本以碳酸钙为主，但它们的晶体结构却存在显著差异，且非典型。此外，宏基因组数据分析显示，从寡营养环境中采集的干湿月奶石样本与外界土壤相比，其细菌群落存在完全不同的特征，且干湿月奶石样本之间的细菌群落亦存在差异。然而，真菌群落在不同干湿月奶石样本之间并未表现出显著差异。本研究首次对两种不同物理特性的月奶石进行了宏基因组分析，并首次报道了韩国首个关键带观测站内洞穴月奶石的微生物多样性研究。