Abstract: This article focuses on the study of the enzymes produced by microorganisms, which have been extensively studied worldwide for their isolation, purification and characterization of their specific properties. Specific microorganisms have been isolated from extreme sources under extreme culture conditions, with the objective that such isolated microbes would possess the capability to bio-synthesize special enzymes. Various offline and online primary resources and literatures have been surveyed and reviewed for this study. Many Bio-industries require enzymes possessing special characteristics for their applications in processing of substrates and raw materials. These enzymes act as bio-catalysts to perform reactions in bio-processes in an economical and environmentally-friendly way as opposed to the use of chemical catalysts. The special characteristics of enzymes are exploited for their commercial interest and industrial applications, which include: tolerance to a varied range of pH, stability of enzyme activity over a range of temperature and pH, thermotolerance, thermophilic nature and other harsh reaction conditions. These microbial enzymes have proven their utility in bio-industries such as food, leather, textiles, animal feed, and in bio-conversions and bio-remediations.