Niche specialization of bacteria in permanently ice‐covered lakes of the McMurdo Dry Valleys, Antarctica

Abstract

Perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, are chemically stratified with depth and have distinct biological gradients. Despite long-term research on these unique environments, data on the structure of the microbial communities in the water columns of these lakes are scarce. Here, we examined bacterial diversity in five ice-covered Antarctic lakes by 16S rRNA gene-based pyrosequencing. Distinct communities were present in each lake, reflecting the unique biogeochemical characteristics of these environments. Further, certain bacterial lineages were confined exclusively to specific depths within each lake. For example, candidate division WM88 occurred solely at a depth of 15 m in Lake Fryxell, whereas unknown lineages of Chlorobi were found only at a depth of 18 m in Lake Miers, and two distinct classes of Firmicutes inhabited East and West Lobe Bonney at depths of 30 m. Redundancy analysis revealed that community variation of bacterioplankton could be explained by the distinct conditions of each lake and depth; in particular, assemblages from layers beneath the chemocline had biogeochemical associations that differed from those in the upper layers. These patterns of community composition may represent bacterial adaptations to the extreme and unique biogeochemical gradients of ice-covered lakes in the McMurdo Dry Valleys.

Microbial diversity of an Antarctic subglacial community and high‐resolution replicate sampling inform hydrological connectivity in a polar desert

“…(). It is possible that deeper lake waters contain more EMB taxa, although, neither Atribacteria nor DHVE6, key EMB‐biomarker phyla, were reported at 30 m (Kwon et al, ).…”

“…This halotolerant, psychrophile is a member of an apparently cosmopolitan lineage of Marinobacter, prevalent throughout the MDV brines (Chua et al, 2018) and is closely related to isolates from both the east and west lobe of Lake Bonney (Ward and Priscu, 1997). Marinobacter sequences were also abundant in 30 m WLB samples reported by Kwon et al (2017). It is possible that deeper lake waters contain more EMB taxa, although, neither Atribacteria nor DHVE6, key EMB-biomarker phyla, were reported at 30 m (Kwon et al, 2017).…”

“…Marinobacter sequences were also abundant in 30 m WLB samples reported by Kwon et al (2017). It is possible that deeper lake waters contain more EMB taxa, although, neither Atribacteria nor DHVE6, key EMB-biomarker phyla, were reported at 30 m (Kwon et al, 2017).…”

Environmental controls on bacteriohopanepolyol profiles of benthic microbial mats from Lake Fryxell, Antarctica

“…Alternatively, a water column source of 2-MeBHP cannot be ruled out. Cyanobacteria and α-proteobacteria are present but comprise a very low proportion of the bacterial phyla in the Lake Fryxell water column (Kwon et al, 2017).…”

A new method for rapid genome classification, clustering, visualization, and novel taxa discovery from metagenome

“…The water columns are dominated by the microbial loop, with few to no metazoans (Priscu et al, 1999) . The water columns of these lakes exhibit permanent chemical and physical stratification, harboring unique bacterial and eukaryal communities adapted to extreme environmental conditions including oligotrophy, low temperature, and hypersalinity (Roberts et al, 2004a;Li et al, 2016b;Kwon et al, 2017). In addition, thick benthic cyanobacterial mats carpet the lake floors to the base of the photic zone, often forming complex pinnacle-shaped structures reaching several centimeters tall (Jungblut et al, 2016;Hawes et al, 2013).…”