Molecular diversity of the microbial community in coloured snow from the Fildes Peninsula (King George Island, Maritime Antarctica)

Snow in Antarctica is a vast terrestrial ecosystem and plays a key role that has likely been underestimated. Algae are the key primary producers on the coloured snow surface, and they support a microbial community that includes bacteria, fungi and/or invertebrates. We analysed microbial communities that co-exist in green and red snow samples from the Fildes Peninsula by Illumina sequencing, Antarctica, as well as the influence of snow physicochemical properties. We detected several species of green algae from Chlorophyta and Ochrophyta as well as fungi and cercozoans. The three red snow samples (RS1, RS2 and RS3) were represented by mixed eukaryotic microalgae fromSanguina,Chloromonasand Trebouxiophyceae. The green snow sample GS5 exhibited lake-to-snow colonisation composed of Trebouxiophyceae, Ulvophyceae and Chrysophyta representatives. The red snow RS4, predominantly byChlainomonassp. from slush layers, which presented a different microbial community from the other red snow samples, was sampled close to green snow sample GS5 near Lake Changhu. The environmental parameters were involved into descriptive differences among these coloured snow samples. The two snow algaeChlainomonasandSanguinawere firstly reported from Antarctica, which indicates distinguished snow algae colonisation that is closely connected with the melting snow at the lake ice-cover. Meanwhile, consistent with previous bacterial community profiles, Proteobacteria and Bacteroidetes were mostly represented in all the coloured snow samples. Polaromonas(Betaproteobacteria) was the most abundant genus, and its presence was reportedly essential for the sustained growth of snow algae.Flavobacteriumfrom Bacteroidetes was the most frequently detected genera in GS5, but the Sphingobacteriia with only a few reads were an interestingly minority in GS5. The snow-algae-associated bacteria were closely related to psychrophilic strains or sequences from low-temperature environments. Many possible factors influence on the coloured snow microbial communities would require attentions, to help understand their occurrence mechanisms, their biogeographic distributions in polar regions.