Antarctica's Deep Lake harbours 'promiscuous' microbes

Washington: Antarctica's Vestfold Hills, Deep Lake, which became isolated from the ocean 3,500 years ago by the Antarctic continent rising, have provided scientists a unique niche for studying the evolution of the microbes that now thrive under such conditions. 

Deep Lake's microscopic inhabitants are dominated by haloarchaea, microbes that require high salt concentrations to grow and are naturally adapted to conditions - at minus 20 degree Celsius - that would prove lethally cold to other organisms. 

A team led by Rick Cavicchioli of the University of New South Wales, Australia partnered with the US Department of Energy Joint Genome Institute (DOE JGI) to generate sequence data from DNA isolated from individual microbes and compared them with metagenomic (microbial community) information sampled at various depths of Deep Lake. 

Cavicchioli said that understanding how haloarchaea can thrive in Deep Lake could be used to develop engineering concepts for reducing energy costs in a variety of situations, such as for cleaning up contaminated sites in permanently or seasonally cold regions. 

He said that owing to the ability of salt-loving enzymes to function under extremes, asserting they could also be used as catalysts for peptide synthesis and enhanced oil recovery, and can function in water-organic solvent mixtures. 

Cavicchioli said that these enzymes will be especially useful for transforming contaminated sites with particularly high levels of petroleum-based products. 

Four isolates in the study represented about 72 percent of the cells in the community. Though gene exchange across species boundaries is considered infrequent, the researchers observed that haloarchaea living in the Lake's hypersaline environment practice it comparatively often, like neighbors "chewing the fat" in a small-town coffee klatch. 

The study has been published online in the journal Proceedings of the National Academy of Sciences (PNAS).