Eurypsychrophilic acidophiles: From (meta)genomes to low-temperature biotechnologies

Abstract

Low temperature and acidic environments encompass natural milieus such as acid rock drainage in Antarctica and anthropogenic sites including drained sulfidic sediments in Scandinavia. The microorganisms inhabiting these environments include polyextremophiles that are both extreme acidophiles (defined as having an optimum growth pH < 3), and eurypsychrophiles that grow at low temperatures down to approximately 4°C but have an optimum temperature for growth above 15°C. Eurypsychrophilic acidophiles have important roles in natural biogeochemical cycling on earth and potentially on other planetary bodies and moons along with biotechnological applications in, for instance, low-temperature metal dissolution from metal sulfides. Five low-temperature acidophiles are characterized, namely, Acidithiobacillus ferriphilus, Acidithiobacillus ferrivorans, Acidithiobacillus ferrooxidans, “Ferrovum myxofaciens,” and Alicyclobacillus disulfidooxidans, and their characteristics are reviewed. Our understanding of characterized and environmental eurypsychrophilic acidophiles has been accelerated by the application of “omics” techniques that have aided in revealing adaptations to low pH and temperature that can be synergistic, while other adaptations are potentially antagonistic. The lack of known acidophiles that exclusively grow below 15°C may be due to the antagonistic nature of adaptations in this polyextremophile. In conclusion, this review summarizes the knowledge of eurypsychrophilic acidophiles and places the information in evolutionary, environmental, biotechnological, and exobiology perspectives.

Regional variation in Swedish acid sulfate soil microbial communities is influenced by temperature and geochemistry

“…The AS soil sites included in this study have developed over a longer period than, for example, rapidly oxidizing sulfidic spoils, and had more exposure to environmental conditions due to draining, for example, warming/freezing, flooding/drought, where the freeze and flood events may have inhibited metal sulfide oxidation. Flooding and water table elevations (generally found around the level of the RZ) provide a barrier for oxidation while the freezing inhibits microbial development as there are not yet known true eurypsychrophilic acidophiles (Dopson et al, 2023). These natural oxidation barriers may potentially break down with climate change as higher latitudes are expected to warm faster and as droughts are expected to become more prolonged and pronounced.…”