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

Abstract

BackgroundThe 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.ResultsIn 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.ConclusionThis 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.

Polyphasic Analysis Reveals Potential Petroleum Hydrocarbon Degradation and Biosurfactant Production by Rare Biosphere Thermophilic Bacteria From Deception Island, an Active Antarctic Volcano

“…Cultured bacterial isolates belonging to Geobacillus, Bacillus, Brevibacillus , and Thermus were explored and showed positives results for the production of lipases ( Muñoz et al, 2013 , 2015 ). Flores et al (2018) partially characterized a thermophilic microorganism identified as Bacillus gelatini , which showed stable glutamate dehydrogenase activity at high temperatures. Additionally, a new thermophile identified as Albidovulum sp.…”

Hot in Cold: Microbial Life in the Hottest Springs in Permafrost

“…Springs in Greenland (Denmark) are heated to 55–62 °C [ 10 ]. A few geothermal sites with temperatures ranging from 50 to 95 °C were found in the Southern Hemisphere in Antarctica [ 11 , 12 ]. At the same time, the temperature of water in the hottest CHS reaches 94–97 °C [ 2 , 3 ], making CHS, to our knowledge, the hottest documented geothermal springs in the Northern Hemisphere permafrost zone.…”

“…Few previous works focused on cyanobacterial mats and the diversity of phototrophic organisms [ 9 , 10 , 13 ] in hydrothermal springs with temperatures below 62 °C, where the illumination plays a crucial role in the establishment of microbial communities. Studies of the prokaryotic diversity of Antarctic hot environments revealed the presence of Geobacillus , Bacillus , Brevibacillus , Thermus , Thermococcus, and Pyrococcus members [ 12 ].…”

Biomarker Profiling of Microbial Mats in the Geothermal Band of Cerro Caliente, Deception Island (Antarctica): Life at the Edge of Heat and Cold

“…Unlike other geothermal areas worldwide ( e.g. , Miller et al , 2009; Wang et al , 2013; Sharp et al , 2014), the microbial community present in Deception Island is weakly characterized, with few studies focused on the isolation of thermophilic and psychrophilic bacteria (Carrión et al , 2011; Muñoz et al , 2011; Bendia et al , 2018a) with potential use for biotechnological applications (Flores et al , 2018). The coexistence of microorganisms with different thermal and metabolic traits (ammonia oxidation, sulfur reduction, and methanogenesis) was attributed to the steep physicochemical gradients (temperature and geochemical) across the island (Fermani et al , 2007; Bendia et al , 2018b, 2018a).…”