Diversity of Microbes in Hot Springs and Their Sustainable Use

Abstract

Hot spring represents diversified microbial community due to its dynamic natural environment and varied geochemical parameters. Hot spring microbiome produced many novel thermostable enzymes which have enormous industrial as well as biotechnological applications. Moreover, studies on hot spring microbiomes could provide better knowledge about the origin and evolution of earliest life, as they are considered to be most similar to the microorganisms inhabiting the primitive Earth. They have been extensively studied throughout the world mainly by 16S rRNA-based clone libraries along with culture-based methods for discovery of novel thermozymes. These thermostable enzymes have several advantages as they are stable at high temperatures (above 60 °C), tolerate wide range of pH and have less chances of getting contaminated by common mesophilic microorganisms. In addition, thermostable enzymes have other advantages like solvent tolerance, substrate selectivity and stability. In this chapter, an attempt has been made to describe the major industrially important thermozymes like lipase, esterase, protease, cellulase, amylase and xylanase, mostly reported from bacteria and archaea through culturable as well as non-culturable approaches. Many thermophilic bacteria have also been shown to produce biosurfactants which can be a better and cheaper alternative to chemically synthesized ones and are being used in enhanced oil recovery, for controlling oil spills, and can also be used as sources of antibiotics against various food-borne pathogens. Majority of the microorganisms that thrive in hot springs are non-culturable. In this regard, metagenomics has enabled the discovery of novel thermozymes which find applications in biotechnological and pharmaceutical industries.