Diversity and ecological role of cyanobacterial benthic microbial mats in five lakes, Lützow-Holm Bay, East Antarctica

Cyanobacteria in bottom benthic mats of five lakes in Lützow-Holm Bay, East Antarctica, were investigated by a multi-facet approach. Morphological (cell biovolume - three groups of cyanobacteria were determined according to their cell morphology: unicellular, filamentous, and heterocystous cyanobacteria) and molecular methods (NGS amplicon sequencing of cyanobacterial 16S rRNA) were combined with a characterization of their ecological role (nitrogenase activity). Five samples were collected from five lakes (Bosatsu-ike, Hotoke-ike, Nyorai-ike, Naga-ike, Skallen-ike), spanning a range of different ecological environments in the deglaciated areas of Skarvnes and Skallen. We evaluated the influence of lake characteristics on the cyanobacterial benthic mats’ diversity and ecophysiological activity. In addition to cyanobacteria, eukaryotic microalgae (diatoms, coccoid, filamentous algae – Chlorophyta and Charophyta) were also distinguished. This research is supported by JARE-60 (Japanese Antarctic Research Expedition) 2018/19 and contributes to the long term monitoring of Antarctic lakes

A Laboratory of Extremophiles: Iceland Coordination Action for Research Activities on Life in Extreme Environments (CAREX) Field Campaign

Existence of life in extreme environments has been known for a long time, and their habitants have been investigated by different scientific disciplines for decades. However, reports of multidisciplinary research are uncommon. In this paper, we report an interdisciplinary three-day field campaign conducted in the framework of the Coordination Action for Research Activities on Life in Extreme Environments (CAREX) FP7EU program, with participation of experts in the fields of life and earth sciences. In situ experiments and sampling were performed in a 20 m long hot springs system of different temperature (57 °C to 100 °C) and pH (2 to 4). Abiotic factors were measured to study their influence on the diversity. The CO2 and H2S concentration varied at different sampling locations in the system, but the SO2 remained the same. Four biofilms, mainly composed by four different algae and phototrophic protists, showed differences in photosynthetic activity. Varying temperature of the sampling location affects chlorophyll fluorescence, not only in the microbial mats, but plants (Juncus), indicating selective adaptation to the environmental conditions. Quantitative polymerase chain reaction (PCR), DNA microarray and denaturing gradient gel electrophoresis (DGGE)-based analysis in laboratory showed the presence of a diverse microbial population. Even a short duration (30 h) deployment of a micro colonizer in this hot spring system led to colonization of microorganisms based on ribosomal intergenic spacer (RISA) analysis. Polyphasic analysis of this hot spring system was possible due to the involvement of multidisciplinary approaches.The authors are grateful to the CAREX Project (Coordination Action for Research Activities on Life in Extreme Environments, FP7-ENV-2007-1 project No. 211700) for funding the fieldtrip to Iceland. A special thanks to N. Walter, ESF and to all other participants in the Icelandic CAREX fieldtrip for fieldwork assistance. The laboratory analyses of FlowCam were supported by a project of the Ministry of Education, Youth and Sports of the Czech Republic, no. LM2010009 CzechPolar²Czech polar stations: Construction and logistic expenses, by project Creating of the Working Team and Pedagogical Conditions for Teaching and Education in the Field of Polar Ecology and Life in Extreme Environment, reg. No. CZ.1.07/2.2.00/28.0190, co-financed by the European Social Fund and the state budget of the Czech Republic and as a long-term research development project no. RVO 67985939. Oxymetric analysis were supported by a Spanish Ministry of Economy and Competitive CGL2011/02254 Grant. F. Mapelli was supported by Università degli Studi di Milano