The first cultivation of the glacier ice alga Ancylonema alaskanum (Zygnematophyceae, Streptophyta): differences in morphology and photophysiology of field vs laboratory strain cells

Abstract

Melting glacier surfaces are unique ecosystems for specialized microbes, frequently harbouring blooms of microalgae with pigments contributing to the darkening of ice surfaces, reducing albedo and enhancing melt rates. The main cause of this phenomenon is algae of the genus Ancylonema. Prior investigation depended on field-collected material because these algae resisted cultivation. To enhance research on how these algae dominate melting ice, we established a strain of Ancylonema alaskanum from an alpine glacier and exposed to temperatures around the freezing point at irradiations of ~10% of full sunlight. The morphology of the culture changed, with the cells becoming longer and turning green by losing their brownish pigmentation, indicating that these dark phenols are crucial for survival in the cryosphere. Photophysiological comparisons of strain and glacial material showed adaptation of the photosynthetic apparatus to prevailing conditions. This laboratorial strain opens possibilities for a wide range of comparative ‘omics’ research.

Adaptation versus plastic responses to temperature, light, and nitrate availability in cultured snow algal strains

“…Recently, Williamson et al, ( 2021 ) demonstrated low N and P cellular quotients of Streptophyte glacier algae sampled from surface ice of the Greenland Ice Sheet, concluding that lower N and P cellular requirements likely reflected adaptation of glacier to their oligotrophic icy environment. However, given that glacier algae have only recently been brought into culture (Remias and Procházková 2023 ), Williamson et al ( 2021 ) were not able to confirm this by culturing glacier algae under nutrient replete conditions and observing cellular responses. Our data show clear stoichiometric plasticity of multiple snow algal strains when grown under snowpack nitrate concentrations as opposed to strains adapted to overall lower nutrient concentrations.…”

The exometabolome of microbial communities inhabiting bare ice surfaces on the southern Greenland Ice Sheet

“…Several of the 20 annotated metabolites found in the exometabolome of microbial communities inhabiting bare ice surfaces have known roles in microbemicrobe interactions in other ecosystems. Here, we briefly highlight some of the metabolites that could be of particular interest for future research on the role of chemical signalling in the dynamics and development of microbial blooms on bare ice surfaces, either in situ or in recently established lab cultures (Jensen et al, 2023;Remias & Proch azkov a, 2023).…”

“…This is a higher temperature than is experienced by bare ice surface microbes in their natural environment, which is also likely to affect the internal metabolic state and exometabolome of the sampled microbes. Despite our inability to control for these and other factors that are likely to induce variability in the supraglacial exometabolome, it is valuable to identify metabolites that are present in environmental samples so that they may subsequently be tested in more controlled lab experiments using recently established cultures of glacier ice algae (Jensen et al, 2023;Remias & Proch azkov a, 2023).…”