Characterization of extremely halophilic archaeal isolates from Indian salt pans and their screening for production of hydrolytic enzymes

Abstract

Halophilic archaea are multi-stress resistant organisms and their enzymes are of special interest as they are generally stable and functional under extreme conditions of temperature and low water activity. The search for novel extremozymes is an ongoing one because of their superior functionality in extreme conditions encountered in various industries. In this study, extremely halophilic archaea were isolated from two salterns (Marakkanam and Vedaranyam) in Tamil Nadu and from three salterns (Sinquetim, Siridao and Ribandar) in Goa, India. All isolates were Gram negative and their pigmentation ranged from light pink to bright orange. Characterization of the ten halophilic archaeal isolates was carried out by morphological, biochemical and molecular techniques. They spanned 6 different genera; Haloferax, Halorubrum, Halococcus, Haloarcula, Halogeometricum, and Haloterrigena. These extremely halophilic archaeal strains were screened for production of hydrolytic enzymes like amylase, esterase, lipase, protease, pectinase and cellulase. Amylase production by Halogeometricum sp. is being reported for the first time. All isolates showed at least one enzyme activity. Halococcus sp., Haloarcula sp., and Haloferax sp. were capable of producing three extracellular enzymes each. Cellulolytic activity was not observed in any of the isolates. Since these enzymes are inherently salt tolerant, they are very promising from the industrial point of view.