Promiscuous Extremophiles Better Oil Spill Cleanup
October 1, 2013

How The Secret Promiscuity Of Antarctic Extremophiles May Help With Oil Spill Cleanup

Brett Smith for - Your Universe Online

Researchers working in Antarctica have created a detailed ecological picture of so-called extremophile bacteria living in extremely salty water that can hit temperatures of -4 degrees Fahrenheit.

The bacteria found in Vestfold Hills, Deep Lake – known as haloarchaea – are giving scientists new information on how life can survive in such dire conditions. They could also potentially provide new tools for bioengineering techniques, according to the research team that published a report on its work in the Proceedings of the National Academy of Sciences.

"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," said report author Rick Cavicchioli, a biology professor at the University of New South Wales, Australia.

Cavicchioli said the bacteria’s unusual nature could provide researchers with unique opportunities for recreating protein synthesis that could lead to enhanced oil recovery.

"These enzymes will be especially useful for transforming contaminated sites with particularly high levels of petroleum-based products," he added.

The extreme nature of the Deep Lake's ecosystem has created a rather homogeneous microbial community, the researchers said. Meanwhile, gene exchange across species boundaries rarely occurs, but the researchers noted that haloarchaea living in the lake practice it relatively often.

"It's intriguing that while gene exchange is rampant, species lineages appear to be maintained by virtue of each species having a high level of specialization, enabling niche partitioning and peaceful coexistence," Cavicchioli said.

"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."

One of the most bizarre aspects of this genetic promiscuity, the team said, is that DNA exchange is not just taking place between species – but among different genera. Additionally, as much as 35,000 letters of code were seen being exchanged, without a letter out of place.

"The long stretches of highly identical shared sequence between the different lake organisms spurred a strong suspicion of potential cross-contamination at first," said co-author Tanja Woyke, a program leader at the US Department of Energy Joint Genome Institute (DOE JGI).

"By painstaking validation of the manually finished and curated genomes, however, we were able to exclude any process-introduced artifacts and confirm that this is true inter-genera gene exchange."

Because the DNA being passed around “lack core genes, it speaks to these microbes' ability to be flexible and collaborative,” Cavicchioli added. “This shuttled gene content could confer such benefits as resistance to viruses or bolster their ability to respond to specific environmental factors. Moreover, the markers that we analyzed indicated that a high level of gene exchange occurs throughout the Deep Lake community."

The researchers singled out one particular gene, tADL, for giving the microbes a relatively "high energy" metabolism that makes it highly proficient at breaking down carbohydrates.

“A key thing about what they eat is that by choosing different food sources they can coexist and continue to reproduce and eke out a living in relative harmony," Cavicchioli explained. "Each lake also has its own unique characteristics, so there is a lot more to be discovered,” he added.

“These Antarctic expeditions represent big logistical investments, with millions in funding from the Australian Antarctic Division and the Australian Antarctic Science Program leveraging the powerful resources of JGI. As a long-term investment strategy, this has proven to be an excellent model of how a flexible group of clever scientists can provide a sure path for enabling strong science to come to fruition."