Microbial diversity in Antarctic Dry Valley soils across an altitudinal gradient

Advocating microbial diversity conservation in Antarctica

Antarctica, a seemingly barren and icy wilderness, is home to a diverse array of microbial life that plays a critical role in sustaining its ecosystems. These resilient microorganisms drive nutrient cycling and carbon sequestration, but their function in global processes remains unclear. This pristine environment faces mounting threats from human activities, climate change, and increasing tourism. Contaminants, non-native species, and microplastics are increasingly reaching even the most remote regions, disrupting delicate microbial communities existing for millions of years. Antarctic microorganisms are not only ecologically significant but also valuable for biotechnological advancements, making their conservation imperative. Climate change exacerbates these threats, altering microbial habitats and promoting shifts in community structure. Tourism growth, though beneficial for education and economic reasons, poses significant challenges through biological and chemical contamination. Despite efforts under the Antarctic Treaty System to protect the region, there is a critical need for enhanced measures specifically targeting microbial conservation. This article underscores the importance of conserving Antarctic microbial diversity. It highlights the intricate microbial ecosystems and the urgency of implementing strategies such as stringent biosecurity measures, sustainable tourism practices, and comprehensive monitoring programs. Additionally, fostering international collaboration and research initiatives is vital for understanding and designing strategies to mitigate the impacts of environmental changes on microbial life. By prioritizing microbial conservation in policy frameworks and strengthening global cooperation, we can safeguard these unique ecosystems and ensure their resilience for future generations.

Distinct microbial communities under different rock-associated microhabitats in the Qaidam Desert

Hypolithic communities, which occupy highly specialised microhabitats beneath translucent rocks in desert and arid environments, have assembly mechanisms and ecosystem functions are not fully understood. Thus, in this study, we aimed to examine the microbial community structure, assembly, and function of light-accessible (under quartz, calcite, and hypolithic lichen-dominated biocrusts) and light-inaccessible microhabitats (under basalt and adjacent soil) in the Qaidam Desert, China. The results showed that hypolithic communities have different characteristics compared with microbial communities of light-inaccessible microhabitats. Notably, hypolithic bacterial communities were dominated by Cyanobacteria, whereas light-inaccessible microhabitats showed a predominance of Bacteroidetes and Proteobacteria. Although the class Dothideomycetes (phylum: Ascomycota) dominated the fungal communities between the two microhabitat types, Sordariomycetes were more prevalent in light-accessible microhabitats. Network and robustness analyses showed that hypolithic communities were less complex and more resilient than microbial communities in light-inaccessible microhabitats. Our results indicated that deterministic processes, specifically homogeneous selection, govern the establishment of bacterial and fungal communities in light-accessible and light-inaccessible microhabitats. The hypolithic community showed an increased frequency of phylotypes that exhibited increased tolerance to functional stress response pathways. In contrast to light-inaccessible microhabitats, light-accessible microhabitats showed a slight decrease and a notable increase in the prevalence of carbon fixation pathways in prokaryotes and carbon fixation in photosynthetic organisms, respectively. For fungi, light-accessible microhabitats enriched saprotrophic and ectomycorrhizal groups. These results highlight the importance of complex and diverse microhabitats in desert regions, which serve as vital shelters for microbes. Combining future research on interactions between hypolithic communities and environments may enhance our current understanding of their pivotal roles in sustaining desert ecosystems. This knowledge then be applied to design and implement informed conservation efforts to preserve these unique rock-associated microhabitats in desert ecosystems.

Microbial community composition of terrestrial habitats in East Antarctica with a focus on microphototrophs

The Antarctic terrestrial environment harbors a diverse community of microorganisms, which have adapted to the extreme conditions. The aim of this study was to describe the composition of microbial communities in a diverse range of terrestrial environments (various biocrusts and soils, sands from ephemeral wetlands, biofilms, endolithic and hypolithic communities) in East Antarctica using both molecular and morphological approaches. Amplicon sequencing of the 16S rRNA gene revealed the dominance of Chloroflexi, Cyanobacteria and Firmicutes, while sequencing of the 18S rRNA gene showed the prevalence of Alveolata, Chloroplastida, Metazoa, and Rhizaria. This study also provided a comprehensive assessment of the microphototrophic community revealing a diversity of cyanobacteria and eukaryotic microalgae in various Antarctic terrestrial samples. Filamentous cyanobacteria belonging to the orders Oscillatoriales and Pseudanabaenales dominated prokaryotic community, while members of Trebouxiophyceae were the most abundant representatives of eukaryotes. In addition, the co-occurrence analysis showed a prevalence of positive correlations with bacterial taxa frequently co-occurring together.