Bacterial diversity within five unexplored freshwater lakes interconnected by surface channels in East Antarctic Dronning Maud Land (Schirmacher Oasis) using amplicon pyrosequencing

Abstract

The Schimacher Oasis, an ice-free plateau in East Antarctic Dronning Maud Land, consists of over 120 freshwater lakes. These lakes are connected largely through four major surface channels. The bacterial diversity in these lake ecosystems remains largely unexplored. In this study, we compared the bacterial diversity in five freshwater lakes (L42, L46, L47, L50, and L51) interconnected by two surface channels using bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP) method. We further compared the resultant bacterial composition from these five lakes with another freshwater lake in the Schirmacher Oasis, Lake Tawani(P), which is not connected through the same surface channels. Using bTEFAP, we differentiated nine different phyla with the phyla Proteobacteria (especially the class Alphaproteobacteria) and Bacteroidetes (the class Sphingobacteria) dominating in lakes interconnected by surface channel 1, while the phyla Chloroflexi and Firmicutes were highly abundant in lakes interconnected by surface channel 2. The operational taxonomic unit (OTU) network and Principle Coordinate Analysis (PCoA) plot based on unweighted UNIFRAC determined that the bacterial assemblages found in these five lakes are different than the bacterial composition residing in Lake Tawani(P). The distribution and the diversity of the bacterial communities in Schirmacher Oasis freshwater lakes that are connected through surface channels may provide an insight into the role of the extreme physico-chemical parameters that help shape microbially driven functional ecosystems in other oases on this icy continent.