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Abstract: Cryoconite holes on glacier surfaces are ice-cold hot spots of microbial diversity and activity but still little is known about their fungal inhabitants. We provide the first report of distinctive fungal communities in cryoconite debris from three valley glaciers at Kongsfjorden, Svalbard. Multivariate analysis of terminal-restriction fragment length polymorphism (T-RFLP) profiles of rRNA ITS amplicons revealed that quite distinct fungal communities were found in cryoconite holes compared with soils from adjacent moraine and tundra sites, and that communities on glaciers with contrasting ice-surface hydrology also differed. Most of the fungi cultured from cryoconite sediment were basidiomycetous yeasts or filamentous Ascomycota (Helotiales/Pleosporales). The latter included aeroaquatic fungi, such as Articulospora and Varicosporium, implying a role for these important freshwater decomposers in the carbon dynamics of cryoconite holes. Matching of the dominant peaks from T-RFLP analysis to predicted peaks of cultured isolates confirmed the abundance of these aeroaquatic fungi but also revealed that most of the dominant T-RFLP peaks did not match any cultured isolates. Considering the prevalence and endangerment of glacial environments worldwide, these findings would suggest that their potential as reservoirs of fungal diversity should not be overlooked. [Copyright &y& Elsevier]

The tundra is the coldest biome described in typical geography and biology textbooks. Within the cryosphere, there are large expanses of ice in the Antarctic, Arctic and alpine regions that are not regarded as being part of any biome. During the summer, there is significant melt on the surface of glaciers, ice caps and ice shelves, at which point microbial communities become active and play an important role in the cycling of carbon and other elements within the cryosphere. In this review, we suggest that it is time to recognise the cryosphere as one of the biomes of Earth. The cryospheric biome encompasses extreme environments and is typified by truncated food webs dominated by viruses, bacteria, protozoa and algae with distinct biogeographical structures. [Copyright &y& Elsevier]

There is an increasing body of evidence to show that viruses are important drivers of microbial evolution and that they can store a great deal of the Earth''s microbial diversity in their genomes. Examination of microbial diversity in polar regions has revealed a higher than expected diversity of viruses, bacteria and eukaryotic microbes. Further, the few available studies in polar regions reveal that viral control of microbial mortality is important in these habitats. In this opinion article, we argue that strong relationships between viruses and their hosts in a range of polar habitats could be key in explaining why polar regions are in fact hot spots of microbial diversity and evolution. Further, we argue that periodic glaciations, and particularly the Neoproterozoic low-latitude glaciation, known as ‘snowball Earth’, could have been periods of intense diversification in aquatic refuges. [Copyright &y& Elsevier]

Microbial communities and soil carbon (C) have been shown to vary in response to increasing vegetation cover during soil development after deglaciation. However, little is known about the ability of microorganisms to utilize various C sources in glacier forefield soils. We supplied ecologically relevant 13 C-labeled C sources ( Chlorella , Penicillium and Festuca ) to three distinct environments (supraglacial sediments, barren soils and vegetated soils) of the Damma glacier area to monitor 13 CO 2 production. We identified prokaryotic and fungal populations able to utilize these sources by using DNA-stable isotope probing coupled with Illumina MiSeq sequencing of ribosomal markers. A high initial 13 CO 2 pulse indicated that 13 C-labeled microbial and plant material were consumed. The 13 C-enriched DNA results indicated that betaproteobacterial taxa affiliated to the families Oxalobacteraceae and Comamonadaceae were important players in C utilization from different sources and present in all environments. In contrast, different fungal taxa played different roles in C degradation depending on the soil environment. Overall, our findings reveal that C utilization is driven by similar prokaryotic populations along a glacier forefield, while the distribution of active fungal populations are more influenced by environmental factors. [ABSTRACT FROM AUTHOR]

Abstract: The contribution of biofilm and artificial feeds for the growth of the pink shrimp Farfantepenaeus paulensis reared in tanks and net cages were evaluated by using stable isotope (δ 13C and δ 15N) analysis. In the net cage experiment, mass balance and mixing equations showed that the biofilm contribution to shrimp growth was over 49% of carbon and 70% of nitrogen. These data suggest that the artificial feed offered in this experiment, although ingested, was not properly incorporated in the shrimp tissue. In contrast, biofilm growing in tanks contributed little to the nitrogen incorporated by the shrimp (maximum of 29%). In this experiment, shrimp presented an unusually large isotope fractionation. These results imply that the shrimp are selectively ingesting some items from the biofilm, or differentially assimilate specific items of the artificial feed, due to differential digestibility. The hypothesis of selective feeding of biofilm microorganisms was corroborated in the experiment with net cages, where shrimp preferentially consumed centric diatoms. This study also demonstrated that shrimp biofilm consumption and the presence of artificial feed largely influenced biofilm formation. The consumption of centric diatoms by shrimp seem to stimulate biofilm chlorophyll-a, while biofilm δ 15N values measured in tanks indicate that microorganisms present in the biofilm absorbs nitrogen released by artificial feed after its decomposition. [Copyright &y& Elsevier]