Cultivable Bacterial Communities in Brines from Perennially Ice-Covered and Pristine Antarctic Lakes: Ecological and Biotechnological Implications

Abstract

The diversity and biotechnological potentialities of bacterial isolates from brines of three Antarctic lakes of the Northern Victoria Land (namely Boulder Clay and Tarn Flat areas) were first explored. Cultivable bacterial communities were analysed mainly in terms of bacterial response to contaminants (i.e., antibiotics and heavy metals) and oxidation of contaminants (i.e., aliphatic and aromatic hydrocarbons and polychlorobiphenyls). Moreover, the biosynthesis of biomolecules (antibiotics, extracellular polymeric substances and enzymes) with applications for human health and environmental protection was assayed. A total of 74 and 141 isolates were retrieved from Boulder Clay and Tarn Flat brines, respectively. Based on 16S rRNA gene sequence similarities, bacterial isolates represented three phyla, namely Proteobacteria (i.e., Gamma- and Alphaproteobacteria), Bacteroidetes and Actinobacteria, with differences encountered among brines. At genus level, Rhodobacter, Pseudomonas, Psychrobacter and Leifsonia members were dominant. Results obtained from this study on the physiological and enzymatic features of cold-adapted isolates from Antarctic lake brines provide interesting prospects for possible applications in the biotechnological field through future targeted surveys. Finally, findings on contaminant occurrence and bacterial response suggest that bacteria might be used as bioindicators for tracking human footprints in these remote polar areas.

First Insights into the Microbiology of Three Antarctic Briny Systems of the Northern Victoria Land

“…The microbiological and physicochemical results previously obtained on BC and TF lake brines, and used in this study, are summarized in Supplementary Material Table S1. Briefly, trace elements (Table S1) were analyzed by inductively coupled plasma sector field mass spectrometry (ICP-SFMS) [3,11,14]. Anions (Table S1) were analyzed by ion chromatography [3,14].…”

“…The TF and BC areas in the NVL host several small perennially ice-covered lakes [7], and some of them conceal brine lenses [8][9][10]. Recently, brines from three Tarn Flat and the Boulder Clay lakes have been analyzed for the prokaryotic component by culture-dependent and -independent approaches [4,5,11,12]. Overall, the prokaryotic community included methanogens, strictly anaerobes, halophiles, and (hyper)thermophiles [4,12].…”

The Variety and Inscrutability of Polar Environments as a Resource of Biotechnologically Relevant Molecules

“…Noteworthy, the study by Rizzo et al [66] represents the first attempt to bioprospect bacterial communities associated to peculiar Antarctic brine habitats, evidencing great potentials in enzyme production. Interestingly, the isolates showed amylase, lipase/esterase, gelatinase, chitinase, DNase and haemolytic activity at low temperature (especially among Pseudomonas isolates) by supporting the role of these communities in the mineralisation of organic matter in briny ecosystems.…”

“…The 19.5% of total isolates showed mucoid aspect, and four isolates (namely Pseudomonas spp. BC1-139 and BC1bis-18 from Boulder Clay, and Psychrobacter TF4-72 and Pseudomonas TF5-192A from Tarn Flat) produced promising amounts of EPS (from a minimum of 20.5 to a maximum of 170.1 μg EPS mL −1 ) [ 66 ].…”

The Spatio-Temporal Variability of Frost Blisters in a Perennial Frozen Lake along the Antarctic Coast as Indicator of the Groundwater Supply

“…In this paper we focus on one of the perennially frozen lakes studied by Guglielmin et al [10] and recently investigated also regarding its microbiological ecosystems [39,40]. In particular, we quantify the temporal variation of the two frost blisters occurring in this lake and the spatio-temporal variations (i.e., sublimation and accretion) of the ice surface in order to assess the origin of the water supply that is responsible of the lake-system dynamic.…”