Isolation and characterization of halophilic isolates from Indian salterns and their screening for production of hydrolytic enzymes

Abstract

Bacterial halophiles are unicellular organisms that can withstand a variety of stresses, and since the hydrolytic enzymes generate are typically stable, specific, and usable under high salinity, extreme temperature, wave action, and tide fluctuation, they are of particular interest. Due to their superior functionality in a wide range of extreme conditions found in different industries, the search for novel extremozymes and extremoproteins has been carried out over the last few decades. Moderately halophilic bacteria were isolated from three salterns in Tamil Nadu (Thoothukudi, Marakkanam, and Kanyakumari), Ernakulum in Kerala, and Ribandar salterns in Goa, India. Most of the halophilic isolates were found to be Gram-positive and also their pigmentation ranged from creamy white to yellow and yellow to bright orange. Out of 1127, characterization of twenty-eight halophilic isolates was carried out by morphological, biochemical, and molecular techniques. They ranged over different genera: Staphylococcus, Stenotrophomonas, Bacillus, Pseudomonas, Enterobacter, Ochrabactrum, and Oceanobacillus. Hydrolases such as amylase, lipase, protease, and cellulase were screened in halophilic bacterial isolates. For the first time, Bacillus paramycoides have been found to produce lipase. At least one enzyme activity was detected in each isolate. Extracellular enzymes were produced by Bacillus sp., Staphylococcus sp., and Pseudomonas sp. Highest protease activity was produced by six isolates with the enzyme activity ranging from 144.27 to 201.25 U/mg. Only a few isolates showed cellulolytic activity. These extracellular enzymes are very important and have a promising role from the viewpoint of industries because they are intrinsically salt tolerant.