Articles of Significant Interest Selected from This Issue by the Editors

摘要

Relative to their global surface area, freshwater lakes are disproportionally active sites of carbon cycling. Few of the key bacterial populations involved in lake dissolved organic matter (DOM) mineralization have been characterized, particularly for bottom lake layers. Denef et al. (p. 14231432) focused on Chloroflexi clade CL500-11, which is the predominant organism in the hypolimnia of the world's largest lakes and likely contributes a significant proportion of the world's freshwater bacterial biomass. Through reconstruction of a nearly complete genome from metagenomic data and metatranscriptomic analysis of Lake Michigan samples, these authors show that CL500-11 plays an important role in the transformation of biologically derived organic matter, particularly nitrogen-rich DOM.Grinding of bedrock by glaciers exposes fresh mineral surfaces capable of supporting microbial life. Microbial use of bedrock minerals, such as pyrite, for energy metabolism generates acid, a key driver of mineral weathering in glaciated terrains. Here, Harrold et al. (p. 14861495) report the isolation of the chemoautotroph Thiobacillus sp. strain RG5 from the subglacial environment at Robertson Glacier in the Canadian Rockies. Aerobic and anaerobic culture experiments with RG5 grown in the presence of thiosulfate, a pyrite oxidation intermediate, indicate that this organism is cold adapted. Microbial consumption of thiosulfate by cold-adapted RG5-like populations may accelerate pyrite oxidation, thereby enhancing mineral weathering in low-temperature environments.