Chloroflexi CL500-11 populations that predominate deep lake hypolimnion bacterioplankton rely on nitrogen-rich DOM metabolism and C1 compound oxidation
Description:The Chloroflexi CL500-11 clade predominates bacterial biomass in oxygenated hypolimnia of deep lakes worldwide, including the world's largest freshwater system, the Laurentian Great Lakes. Trains that allow CL500-11 to thrive and its biochemical role in these environments are currently unknown. Here, we found that a CL500-11 population was mostly present in off-shore waters along a transect in ultra-oligotrophic Lake Michigan (a Laurentian Great Lake). It occurred throughout the water column in spring, and only in the hypolimnion during summer stratification, contributing up to 18.1% of all cells. Genome reconstruction from metagenomic data suggested an aerobic, motile, heterotrophic lifestyle with additional energy gained through carboxidovory and methylovory. Comparisons to other available streamlined freshwater genomes revealed that CL500-11 contains disproportionate number of cell wall/capsule biosynthesis genes and the most diverse DOM substrate uptake spectrum, particularly for peptides. In situ expression patterns indicate the importance of DOM uptake and protein/peptide turnover, as well as Type I and Type II carbon monoxide dehydrogenase and flagellar motility. Location in the water column influenced expression patterns most, marked by increased bacteriorhodospin expression and a response to oxidative stress in surface compared to deep waters. While carrying multiple adaptations to an oligotrophic and mesotrophic lakes indicate the ability to thrive under conditions where resources are more plentiful. Our data indicate that CL500-11 plays an important role in nitrogen-rich DOM mineralization in the extensive deep lake hypolimnion habitat.
You May Also Like: