Table_1_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.

白岩洞为一处石灰岩洞穴，已被提名为首例韩国关键带观测站（CZO）。月奶石作为一种由多种碳酸盐矿物构成的著名洞穴沉积物，其特征已被详细阐述。为了表征白岩洞的月奶石，我们进行了矿物学分析，并采用高通量16S rRNA基因测序技术，分析了干湿月奶石样品中的微生物群落，包括细菌和真菌。研究结果表明，尽管干湿月奶石样品主要由碳酸钙（CaCO3）组成，但它们表现出不同且非典型的晶体结构。此外，宏基因组数据分析揭示，从寡营养环境采集的干湿月奶石样品与外界土壤相比，其细菌群落存在显著差异，甚至在干湿月奶石样品之间也观察到细菌群落的差异。然而，真菌群落在不同干湿月奶石样品之间并未显示出显著差异。本研究首次对两种具有不同物理特性的月奶石进行了宏基因组分析，并首次报告了位于韩国首例关键带观测站洞穴中的月奶石的微生物多样性。