Unraveling Microbial Activity in Alpine Snow using metatranscriptomics: A 24-Hour Study of Diurnal Variations

Understanding microbial activity in snowpacks is essential for unveiling the dynamics of cold ecosystems, yet little is known about how this activity changes between day and night. To address this knowledge gap, we conducted a 24-hour study on a snowpack located in the French Alps, sampling snow at five-hour intervals across different layers —from the surface to the basal layer in contact with soil.

For each layer and time point, we sampled snow to assess microbial activity using omic techniques, like metagenomic and metatranscriptomics, coupled to the analysis of environmental parameters, including sunlight duration, snow pH and temperature. Our results revealed significant diurnal variations: sunlight, pH and temperature fluctuated throughout the 24-hour period, with microbial activity showing corresponding changes. For example, algae affiliated with Chlorella and Volvox, or fungi affiliated with Rhizophagus and Penicillium, showed different transcriptomic responses to diurnal changes in surface and basal samples. These findings highlight the influence of environmental factors on microbial processes in snow and provide the first insights into how microbial activity adapts to the diurnal cycle in snowpacks.

This study contributes to understanding microbial dynamics in snow-covered ecosystems, shedding light on the interplay between microorganisms and their environment over short temporal scales.