20-EPN2-078: Metagenomic analysis of the outstanding moonmilk speleothems from Grotta Nera, Majella National Park
Visit by Martina Cappelletti, University of Bologna (Italy) to TA2.19 Center for Microbial Life Detection, Medical University Graz (Austria).
Dates of visit: 4-7 October 2021, 26 April 2022 (virtual visit)
Report Summary: This project focused on the analysis of three samples from the Black cave (Grotta Nera) located in Majella Park (Abruzzi region, Italy). This cave presents outstanding calcitic moonmilk structures that are unique in the World in terms of both abundance and dimension.
Metagenomic and metabolomic analyses of three samples (A1, apical; A2, lateral; A3, core) collected from one of the moonmilk speleothem from Grotta Nera, were performed. The DNA was extracted using the DNA powersoil kit (Qiagen) modified to include a bead-beating step with MagNA lyser (Roche) for the initial sample treatment. MG-RAST was used to analyse the metagenomic data considering both the taxonomy composition and the functional categories (KO categories). The taxonomy composition of the metagenomic sequences indicated that the dominant phyla were Proteobacteria, Actinobacteria, Firmicutes, Planctomycetes, Acidobacteria, and Verrucomicrobia. Actinobacteria were more abundant in the A1 and A2 as compared to the A3 sample, while in A3 Proteobacteria (in particular, Betaproteobacteria) was enriched as compared to other two samples. The metabolomic analysis was carried out using NMR, extracting the metabolites from 100 mg of each sample (in triplicate). The results indicated that in A2 and A3 samples were enriched by specific metabolites (glycerol in A3 and alanine, acetate, ethanolamine and 3-hydroxybutirate are enriched in A2) suggesting distinct metabolic activities in the microbial communities of these two samples.
Read the full scientific report, with kind permission from Martina Cappelletti.