Glacial catch: cold loving, radiation-resistant bacteria
doi:10.1038/nindia.2016.73 Published online 21 June 2016
In the ice-clad mountains of Sikkim in the north east of India, some unique bacteria have been thriving in a glacier – not just surviving in the extreme temperatures but resisting harmful radiations and churning out industrially important enzymes. Researchers scouring the glacier of East Rathong in West Sikkim have now unlocked the genetic secrets behind the capability of these bacteria to adapt to such extreme cold1,2,3 – a property that will be of value for enzyme-driven industrial applications.
Scientists have been studying these glaciers in the remote mountains of Sikkim to track their volume change or retreat. But not much was known of their microbial population. Researchers from the CSIR-Institute of Himalayan Bioresource Technology (CSIR-IHBT), Himachal Pradesh, teamed up with peers from the Sikkim State Council of Science and Technology to sequence the complete genomes of some bacteria collected from the glaciers – two species of the genus Arthrobacter genus and one of Microterricola.
“Gene sequencing showed that the bacteria owe their ability to adapt to harsh glacial conditions and produce cold-active enzymes to specific genes,” Rakshak Kumar, one of the researchers from CSIR-IHBT told Nature India. The researchers say this is the first report on complete genome sequence of any bacteria reported from East Rathong glacier. The cold-active enzymes might find potential use in industries that make detergents, drugs, paper and food.
Experiments showed that Arthrobacter bacteria have a yellow pigment and produced enzymes such as amylase, protease and cellulose that are active even at temperatures as low as 5°C. The researchers also identified specific genes that code for industrially important enzymes such as pullulanase, alcohol dehydrogenase and alkaline phosphatase.
“Since the enzymes are active at low temperatures, they could reduce the need for certain high temperature chemical reactions, thus saving substantial energy in large-scale industrial processes,” Kumar, who worked with CSIR-IHBT colleagues Sanjay Kumar and Dharam Singh, said. One of the common industrial processes where such enzymes could be used is peeling of leather using proteases. Cold-active enzymes can finish this process at room temperature instead of raising the temperature to 37°C, he explained.
At high altitudes, the bacteria are constantly exposed to harmful ultraviolet radiations. Such radiation-rich environment endows the bacteria with an anti-radiation chemical defense which could be exploited commercially to develop anticancer drugs, antioxidants and even radiation-blocking sunscreens, Kumar said. “We are now planning to assess the microbial populations at different layers of ice core which will help us reconstruct past environmental changes and related human activities,” he said.
Since cold-active enzymes show high catalytic efficiencies at low temperatures, this research is a step towards exploiting their full potential, said Anil Kumar Saxena, who studies cold-active bacteria at the Indian Agricultural Research Institute, New Delhi. The abilities of the enzymes to operate at low temperatures save energy and cost, prevent undesired chemical transformations and loss of volatile compounds, reducing the chances of contamination, he added. Cold-active enzymes such as proteases and amylases have been isolated and purified from various microorganisms but further research is needed to fully exploit them commercially, Saxena said.
1. Kumar, R. et al. Complete genome sequence of Arthrobacter sp. ERGS1:01, a putative novel bacterium with prospective cold active industrial enzymes, isolated from East Rathong glacier in India. J. Biotechnol. 214, 139-140 (2015)
2. Kumar, R. et al. Complete genome sequence of Arthrobacter alpinus ERGS4:06, a yellow pigmented bacterium tolerant to cold and radiations isolated from Sikkim Himalaya. J. Biotechnol. 220, 86-87 (2016)
3. Sharma, H. et al. First complete genome sequence of a species in the genus Microterricola, an extremophilic cold active enzyme producing bacterial strain ERGS5:02 isolated from Sikkim Himalaya. J. Biotechnol. 222, 17-18 (2016)