Alicyclobacillus sp. strain CC2, a thermo-acidophilic bacterium isolated from Deception Island (Antarctica) containing a thermostable superoxide dismutase enzyme

A gram-positive, rod-shaped, aerobic, thermo-acidophilic bacterium CC2 (optimal temperature 55℃ and pH 4.0), belonging to the genus Alicyclobacillus was isolated from geothermal soil collected from “Cerro Caliente”, Deception Island, Antarctica. Owing to the harsh environmental conditions found in this territory, microorganisms are exposed to conditions that trigger the generation of reactive oxygen species (ROS). They must have an effective antioxidant defense system to deal with this oxidative stress. We focused on one of the most important enzymes: superoxide dismutase, which was partially purified and characterized. This study presents the first report of a thermo-acidophilic bacterium isolated from Deception Island with a thermostable superoxide dismutase (SOD)

A thermophilic microorganism from Deception Island, Antarctica with a thermostable glutamate dehydrogenase activity

Abstract Background The Antarctic continent is a source of extreme microorganisms. Millions of years of isolation have produced unique biodiversity with adaptive responses to its extreme environment. Although the Antarctic climate is mainly cold, the presence of several geothermal sites, including thermal springs, fumaroles, hot soils and hydrothermal vents, provides ideal environments for the development of thermophilic and hyperthermophilic microorganisms. Their enzymes, called thermoenzymes, are the focus of interest in both academic and industrial research, mainly due to their high thermal activity and stability. Glutamate dehydrogenase, is an enzyme that plays a key role in the metabolism of carbon and nitrogen catalyzing reversibly the oxidative deamination of glutamate to alpha-ketoglutarate and ammonium. It belongs to the family of oxidoreductases, is widely distributed and it has been highly regarded for use as biosensors, particularly for their specificity and ability to operate in photochemical and electrochemical systems. However, the use of enzymes as biosensors is relatively problematic due to their instability to high temperatures, organic solvents and denaturing agents. The purpose of this study is to present the partial characterization of a thermophilic microorganism isolated from Deception Island, Antarctica, that displays glutamate dehydrogenase activity. Results In this work, we report the isolation of a thermophilic microorganism called PID15 from samples of Deception Island collected during the Antarctic Scientific Expedition ECA 46. This microorganism is a thermophile that grows optimally at 50 °C and pH 8.0. Scanning electron microscopy shows rod cells of 2.0 to 8.0 µm of length. Phylogenetic analysis of 16S rRNA gene revealed that this microorganism is closely related to Bacillus gelatini. This microorganism contains a thermostable glutamate dehydrogenase with optimal activity at pH 8.0 and temperatures for its activity from 37 to 50 °C, range of temperature of interest for biotechnological applications. This glutamate dehydrogenase is a highly thermostable enzyme. Conclusion This is the first report of a microorganism from Antarctica containing a thermostable glutamate dehydrogenase that maintains its activity in a broad range of temperatures making it of potential interest for biotechnological applications