Abstract

Investigation of glacial habitats became a priority due to the impact of climate changes on the dynamics of Polar and alpine glaciers. Our study focused on cave ice microbiome unraveled the diversity of total and active bacterial communities from the 13,000 years old ice chronosequence of Scarisoara Ice Cave, Romania. Vertical ice coring of the perennial ice block was carried out, reaching a record depth of 25.3 m. Radiocarbon dating of the ice core indicated a linear chronosequence up to 13,000 years B.P. 16 melted ice samples from every 1,000 years interval were filtered and used for total DNA and RNA extraction and geochemical analyses. Chemical parameters revealed large variations for the last 5 centuries followed by a stable period, and significant changes in the 5000 years B.P. ice layer. Bacterial diversity based on 16S rRNA gene MiSeq Illumina sequencing of both gDNA and cDNA is currently underway. Correlation with the chemistry of the ice substrate will unravel the microbial resilience, highlighting the active community composition in this habitat for the last 13,000 years. Total and viable microbial content of each sample was quantified by qPCR and LIVE/DEAD staining, indicating a correlation with age and organic content of the ice. This report of the oldest cave ice chronosequence could contribute to identifying biomarkers of climate and environmental changes.