Microbial Assemblages in Pressurized Antarctic Brine Pockets (Tarn Flat, Northern Victoria Land): A Hotspot of Biodiversity and Activity

• Published in: Microorganisms
• Main Authors: Maria Papale, Angelina Lo Giudice, Antonella Conte, Carmen Rizzo, Alessandro C. Rappazzo, Giovanna Maimone, Gabriella Caruso, Rosabruna La Ferla, Maurizio Azzaro, Concetta Gugliandolo, Rodolfo Paranhos, Anderson S. Cabral, Vincenzo Romano Spica, Mauro Guglielmin
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2019
• Subjects: brine pockets; hyperthermophiles; sulphur-reducing bacteria; methanogens; metabolic potential; Biology (General); QH301-705.5; Antarctic; Ross Ice Shelf; Tarn Flat; Victoria Land; Antarc*; Ice Shelf
• Online Access: https://doi.org/10.3390/microorganisms7090333; https://doaj.org/article/f2cb34140a274b319479250b804f39de

Two distinct pressurized hypersaline brine pockets (named TF4 and TF5), separated by a thin ice layer, were detected below an ice-sealed Antarctic lake. Prokaryotic (bacterial and archaeal) diversity, abundances (including virus-like particles) and metabolic profiles were investigated by an integrated approach, including traditional and new-generation methods. Although similar diversity indices were computed for both Bacteria and Archaea, distinct bacterial and archaeal assemblages were observed. Bacteroidetes and Gammaproteobacteria were more abundant in the shallowest brine pocket, TF4, and Deltaproteobacteria, mainly represented by versatile sulphate-reducing bacteria, dominated in the deepest, TF5. The detection of sulphate-reducing bacteria and methanogenic Archaea likely reflects the presence of a distinct synthrophic consortium in TF5. Surprisingly, members assigned to hyperthermophilic Crenarchaeota and Euryarchaeota were common to both brines, indicating that these cold habitats host the most thermally tolerant Archaea. The patterns of microbial communities were different, coherently with the observed microbiological diversity between TF4 and TF5 brines. Both the influence exerted by upward movement of saline brines from a sub-surface anoxic system and the possible occurrence of an ancient ice remnant from the Ross Ice Shelf were the likely main factors shaping the microbial communities.