Surviving in Antarctic conditions takes more than cold-resilience for bacteria, recent research from the Center for Cellular and Molecular Biology found.
Using six different stressors in lab conditions, from temperature stress to pH change stress to salt and oxidative stress, the researchers were able to test bacterial resistance in the environments they are likely to encounter in Antarctica. In Antarctic glaciers, bacteria are likely to experience extreme cold, in thermal vents extreme heat, and in dried up lakes high levels of salinity. Often, bacteria experience more than one stress factor at a time.
Tests were carried out on ten different bacteria strains, which were grown separately and exposed to different conditions. A number of mutant bacteria developed from a strain of Pseudomonas syringae Lz4w, were also tested so that researchers could identify some of the genetic factors that allowed bacteria to develop stress resilience.
Researchers found that of all the stress conditions, the bacteria strains were better able to tolerate alkaline conditions. The bacteria did not fare so well under acidic conditions, which bacteria can face in Antarctic glaciers that contain some mineral acids.
Other stress tolerance levels varied depending on the bacteria strain. For example, Arthrobacter kerguelensis survived oxidation stress better than Pseudomonas meridiana. Under Ultra-Violet radiation, most of the bacteria strains died.
“Our investigation on tolerance of cold-adapted Antarctic bacteria to other environmental stressors fills the void in the present state of knowledge on the stress-adaptability of Antarctic bacteria,” the authors wrote. “The alkali-tolerance of all of the cold-tolerant Antarctic strains reveals their similarity with some other cold-tolerant bacteria isolated some time back from the Himalayan glacier.”
Researchers also found that bacteria that were exposed to multiple stress factors developed multi-stress protective molecules from proteins, lipids or other types of molecules which allowed them to be more resilient.
By looking into some of these proteins, the researchers were able to begin developing an understanding of the genetic elements that allowed bacteria to develop a tolerance for multiple stressful conditions. The findings could provide insights in the development of resilient bacteria strains through genetic engineering.
“The multistress-protective potential of a metabolic enzyme, as evidenced in this study, reveals intricacy in the mechanism involved in stress adaptation of bacteria,” the authors concluded.