Microbial Hotspots in Lithic Macrohabitats Inferred from DNA Fractionation and Metagenomics in the Atacama Desert

The existence of microbial activity hotspots in temperate regions of Earth is driven by soil heterogeneities, especially the temporal and spatial availability of nutrients. Here we investigate whether microbial activity hotspots also exist in lithic microhabitats in one of the most arid regions of the world, the Atacama Desert in Chile. While previous studies evaluated the total DNA fraction to elucidate the microbial communities, we here for the first time use a DNA separation approach on lithic microhabitats, together with metagenomics and other analysis methods (i.e., ATP, PLFA, and metabolite analysis) to specifically gain insights on the living and potentially active microbial community. Our results show that hypolith colonized rocks are microbial hotspots in the desert environment. In contrast, our data do not support such a conclusion for gypsum crust and salt rockenvironments, because only limited microbial activity could be observed. The hypolith community is dominated by phototrophs, mostly Cyanobacteria and Chloroflexi, at both study sites. The gypsum crusts are dominated by methylotrophs and heterotrophic phototrophs, mostly Chloroflexi, and the salt rocks (halite nodules) by phototrophic and halotolerant endoliths, mostly Cyanobacteria and Archaea. The major environmental constraints in the organic-poor arid and hyperarid Atacama Desert are water availability and UV irradiation, allowing phototrophs and other extremophiles to play a key role in desert ecology

Modified scale crystallization and dispersion stability in magnetic water treatment

The effects of magnetic water treatment (MWT) devices are discussed with the emphasis on modified dispersion stability and modified CaCO3 crystallization. MWT mechanism, most probably consisting of several interacting effects, is strongly dependent on water composition, solid phase presence and working conditions

“It Is Not Natural Anymore”: Nutrition, Urbanization, and Indigenous Identity on Bolivia’s Andean Plateau

The objective of this article was to characterize how urbanization and indigenous identity shape nutrition attitudes and practices in El Alto, a rapidly urbanizing and predominantly indigenous (Aymara) community on Bolivia’s Andean plateau. We took a qualitative ethnographic approach, interviewing health care providers ( n = 11) and conducting focus groups with mothers of young children ( n = 4 focus groups with 25 mothers total [age = 18–43 years, 60% Aymara]). Participants generally described their urban environment as being problematic for nutrition, a place where unhealthy “junk foods” and “chemicals” have supplanted healthy, “natural,” “indigenous” foods from the countryside. Placing nutrition in El Alto within a broader context of cultural identity and a struggle to harmonize different lifestyles and worldviews, we propose how an intercultural framework for nutrition can harmonize Western scientific perspectives with rural and indigenous food culture.</jats:p

The CCL-K11 on-going key comparison. Final report for the period 2018 to 2020

Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</jats:p