Extremophiles: An Overview of Microorganism from Extreme Environment

Abstract

Extremophilic organisms are primarily prokaryotic (archaea and bacteria), with few eukaryotic examples. Extremophiles are defined by the environmental conditions in which they grow optimally. The organisms may be described as acidophilic (optimal growth between pH 1 and pH 5); alkaliphilic (optimal growth above pH 9); halophilic (optimal growth in environments with high concentrations of salt); thermophilic (optimal growth between 60 and 80 °C); hyperthermophilic (optimal growth above 80 °C); psychrophilic (optimal growth at 15 °C or lower, with a maximum tolerant temperature of 20 °C and minimal growth at or below 0 °C); piezophilic, or barophilic (optimal growth at high hydrostatic pressure); oligotrophic (growth in nutritionally limited environments); endolithic (growth within rock or within pores of mineral grains); and xerophilic (growth in dry conditions, with low water availability). Some extremophiles are adapted simultaneously to multiple stresses (polyextremophile); common examples include thermoacidophiles and haloalkaliphiles. Extremophiles are of biotechnological interest, as they produce extremozymes, defined as enzymes that are functional under extreme conditions. Extremozymes are useful in industrial production procedures and research applications because of their ability to remain active under the severe conditions typically employed in these processes. The study of extremophiles provides an understanding of the physicochemical parameters defining life on Earth and may provide insight into how life on Earth originated. The postulations that extreme environmental conditions existed on primitive Earth and that life arose in hot environments have led to the theory that extremophiles are vestiges of primordial organisms and thus are models of ancient life. HighlightsExtremophiles are micro-organisms that inhabit some of earth"s most hostile environments which produce extremozymes useful in industrial production procedures and research applications because of their ability to remain active under the severe conditions typically employed in these processes.

Thermophilic and alkaliphilic Actinobacteria: biology and potential applications

“…Polyextremophiles and polyextremotolerant actinobacterial species also exist in environments with two or more extreme conditions. Polyextremophiles can adapt to environments with multiple stresses (Gupta et al, 2014 ), which include alkalithermophilic, thermoacidophilic, thermophilic radiotolerant, haloalkaliphilic, and thermoalkalitolerant actinobacteria. Their incidence has been documented in distinct extremes of geographical locations such as the Arctic (Augustine et al, 2012 ) and Antarctic (Gousterova et al, 2014 ) regions, oceans (Raut et al, 2013 ), hot springs (Chitte and Dey, 2002 ), and deserts (Kurapova et al, 2012 ).…”

Isolation and Characterization of Thermophilic Bacteria from Jordanian Hot Springs:Bacillus licheniformisandThermomonas hydrothermalisIsolates as Potential Producers of Thermostable Enzymes

“…Thermophiles can be categorized into moderate thermophiles (growth optimum, 50–60°C), extreme thermophiles (growth optimum, 60–80°C), and hyperthermophiles (growth optimum, 80–110°C) [ 17 ]. Thermophiles have been isolated from different ecological zones (e.g., hot springs and deep sea) of the earth.…”

The Performance of a Fixed-Bed Anaerobic Bioreactor Using Sulfate-Reducing Bacterial Consortium from Sikidang Crater Sediments

“…Sediment from Sikidang Crater, located in Dieng Highland, Banjarnegara, Central Java, has unique physicochemical properties, such as pH values in the range of 2 to 3, a temperature between 30 °C and 100 °C, and high sulfate content. Therefore, SRB isolated from Sikidang Crater may potentially be applied to treat AMD [23]. It is important to evaluate the activity of SRB from the Sikidang Crater sediment attached to the Indonesian natural zeolite medium (as their inert support) within the FBR system.…”