International Journal of Agriculture, Environment and Biotechnology
Year : 2014, Volume : 7, Issue : 2
First page : ( 371) Last page : ( 380)
Print ISSN : 0974-1712. Online ISSN : 2230-732X.
Article DOI : 10.5958/2230-732X.2014.00258.7

Extremophiles: An Overview of Microorganism from Extreme Environment

Gupta G.N.^1,2,*, Srivastava S.², Khare S.K.³, Prakash V.¹

¹Department of Biochemistry and Biochemical Engineering, JSBB, Sam Higginbottom Institute of Agriculture, Allahabad, Uttar Pradesh- 212007, India

²Center for Sugarcane Biotechnology, U.P. Council of Sugarcane Research, Shahjahanpur, U.P.- 242001, India

³Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi- 110016, India

*Email: gorakh100@yahoo.co.in

Online published on 24 June, 2014.

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.

Highlights

Extremophiles 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.

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Keywords

Extremophiles, extremozymes, psychrophiles, thermophiles, mesophiles, halophiles, acidophiles.

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