Highlights of recent publications
Elucidating the Role of Chloroflexi That Bloom in the Depths of the World's Largest Lakes > AEM
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. 1423–1432) 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.
Microbial evolution in the wild > Science
Microbial communities, which drive Earth’s geochemical cycles, can rapidly respond to change, but the proportion of this response that can be attributed to evolutionary processes, rather than species composition or gene expression shifts, remains an unresolved question. Most evolutionary rate estimates are available for nucleotide substitution rates and derive from laboratory measurements. It is difficult to know how relevant these rates are for geochemical environments, because studies on natural populations have been restricted to pathogens and endosymbionts.
Linking genotype to ecology in ecosystem context > PNAS