The Deep Lake, situated within the heart of the Antarctica’s Vestfold Hills, could show scientists how extremophiles are able to survive within extraordinarily cold climates. The lake was cut off from the ocean some 3,500 years ago, culminating in a saltwater ecosystem, ripe for scientific investigation.
The researchers’ findings were published in the journal Proceedings of the National Academy of Sciences (PNAS), in the Sept. 30 issue.
The ecosystem thrives in liquid at extremely low temperatures, permitting the team to study the evolution of microbial life forms, capable of thriving under such unique conditions. The Deep Lake is primarily occupied by haloarchaea. Haloarchaea are microorganisms that necessitate high concentrations of salt for sustaining optimal growth. Their high densities within water can result in some occupied areas turning a pink/red hue, as a consequence of their high levels of carotenoid pigments.
In addition, haloarchaea are capable of surviving at temperatures as low as minus 20°C – conditions which would destroy most other organisms.
The team was led by Rick Cavicchioli, based at the University of New South Wales, Australia, who collaborated with the U.S. Department of Energy Joint Genome Institute. The researchers sequenced the genetic material of haloarchaea microorganisms, and then contrasted the resultant data against microbes found at various depths within the lake.
The grueling temperatures of the lake are obvious when looking at the populations that inhabit the area. Only four microbial isolates made up around 72 percent of all the cells present, showing the limited diversity present.
Horizontal Gene Transfer
In other environments, microorganisms are able to pass on their genetic material between one another; this process is called horizontal gene transfer, but remains a relatively
infrequent process. However, unexpectedly, the haloarchaea of Deep Lake shuffled their genes much more frequently, a finding that Cavicchioli discussed in a recent press release:
“Haloarchaea are known for being ‘promiscuous,’ that is, prone to exchange DNA between themselves. Our study demonstrated that this exchange occurs at a much higher level than has previously been documented in nature. They communicate, share, specialize, and coexist.”
What makes this finding so remarkable is that the haloarchaea “communicate” with particular types of microorganisms and, in doing so, share vast amounts of genetic information; sequences containing 35,000 letters of genetic code were found to be passed on.
He suggests that content from the disseminated genes could confer resistance to viral infection, or improve their adaptation to particular environmental factors.
With regard to the future, Cavicchioli believes that many more amazing mysteries of the Antarctica are due to be eked out; it’s just a matter of further scientific expeditions being given the go ahead:
“Every time we ‘poke an omics stick’ in there we find things we never expected.”
Appreciating how the haloarchaea are able to flourish within Deep Lake could prove key to the development of engineering concepts for reigning in the energy expenditure of numerous tasks. For example, since the salt-loving enzymes can function at extremely low temperatures, Cavicchioli suggests these enzymes might be useful for improved oil recovery operations, as well as catalysis of peptide synthesis.
The researchers’ endeavors into these gene shuffling microbes could be just the beginning of new scientific discovery within the Antarctica. Only a few short weeks ago, scientists published a research study proclaiming they had found ancient life within Lake Hodgson and, it seems, the harder we look, the more information we glean.
By: James Fenner