How do salt-loving microbes survive?
doi:10.1038/nindia.2016.100 Published online 5 August 2016
Biotechnologists at the Modern College in Pune have identified the mechanisms that enable the unique microorganisms called haloarchaea to survive in extremely salty water and adapt to fluctuating salt concentrations1.
They isolated haloarchaea from Mumbai's hyper-saline salterns, shallow ponds used for production of common salt by natural evaporation of sea water. Out of 34 strains isolated, they chose Haloarcula marismortui RR12 and studied its response to salinity stress by exposing to varying concentrations of salt.
They found that the bacteria employs a survival strategy by sequestering sodium or potassium ions so as to maintain the ionic concentration inside the cell equivalent to or higher than the external environment. It accumulates chloride ions in higher salt concentrations, and sequesters potassium ions at low salt concentrations.
Additionally — as a response to salinity stress — it produces an intriguing group of small heat shock proteins (sHsp) and increases the production of protective red carotenoid pigment. The production of excessive carotenoid is indicative of the red pigment's role as one of the physiological means of combating stress, the researchers say.
"This is the first report explaining the mechanism of adaptation of haloarchaea", corresponding author Rebecca Thombre told Nature India.
1. Thombre, R. S. et al. Biology and survival of extremely halophilic archaeon Haloarcula marismortui RR12 isolated from Mumbai salterns, India in response to salinity stress. Sci. Rep. 6, 25642 (2016) doi: 10.1038/srep25642