Microbiome of Supraglacial Systems on the Aldegonda and Bertil Glaciers (Svalbard)

Microbial biomass, diversity of culturable bacteria and micromycetes, and the number of functional nitrogen cycle genes in the supraglacial systems of the Aldegonda and Bertil glaciers have been studied. The biomass of microorganisms varies from 2.54 to 722 µg/g substrate. It is shown for the first time that the major part (78.7–99.8%) of microbial biomass in supraglacial objects is represented by fungi rather than by prokaryotes, and the main part (70 to 90%) of the fungal biomass consists of mycelium with the length varying from 6.70 to 537.51 m/g substrate. The counts of prokaryotes vary from 2.4 × 10⁸ to 1.95 × 10⁹ cells/g substrate. The length of actinomycete mycelium falls into the range of 2.6–62.61 m/g substrate. The counts of culturable bacteria and actinomycetes vary from 3.3 × 10⁴ to 1.2 × 10⁶ CFU/g substrate and of micromycetes, from 2.2 × 10¹ to 1.7 × 10⁴ CFU/g substrate. Bacteria of the genera Arthrobacter, Bacillus, Rhodococcus, Streptomyces and micromycetes of the genera Antarctomyces, Cadophora, Hyphozyma, Teberdinia and Thelebolus are dominants. The micromycetes Antarctomyces psychrotrophicus, Hyphozyma variabilis and Teberdinia hygrophila are found in Svalbard for the first time. The copy number of amoA genes in ammonium-oxidizing bacteria varies from 5.33 × 10⁶ to 4.86 × 10⁹/g substrate; of nitrogen fixation genes nifH, from 9.89 × 10⁷ to 9.81 × 10¹⁰/g substrate; and denitrification genes nirK, from 4.82 × 10⁷ to 3.34 × 10¹⁰/g substrate. These results indirectly suggest the leading role of fungi in the microbiome of the supraglacial objects in Svalbard and a considerable contribution of prokaryotes to the emission of greenhouse gases there.