A Bacillus sp. which can tolerate 10% (w/v) NaCl, produces esterase optimally in Marine Broth 2216 medium containing 1% (w/v) NaCl. The serine type esterolytic enzyme has a molecular weight of 35.0 kDa and is denatured into polypeptides of molecular weights 20 kDa and 15 kDa. The esterase was most active at pH 8.0, the pH of the seawater at the site of collection and is stable in the pH range 6.0–9.0.
The optimum temperature of activity of this esterase is 45 degree C and the enzyme is very stable at 50 degree C. Our esterase shows about 100% activity when incubated with 1 M NaCl. When incubated for a period of 10 days in the presence of 30–70% dimethylsufoxide (DMSO), the specific activity increased by approximately two–threefold compared to the enzyme in aqueous buffer throughout the period of study. High specific activity was maintained by our enzyme when incubated with 50% DMSO for 10 days. Extreme stability in DMSO could make this enzyme a potential immobilized biocatalyst for application in non-aqueous based continuous bioprocesses.
The first ribonuclease from the Cytophaga-Flavobacterium-Bacteroides phylum, dominant in the marine environment, and also from the first Bizionia species isolated from the tropics was purified and characterized. Extracellular ribonuclease production occurred when the culture medium contained 5% – 7% (w/v) NaCl. The pH and temperature optima are 6.5 and 35 degree C respectively and the enzyme retains more than half of its activity (relative to optimal assay conditions) after one hour pre-incubation separately with 5% (w/v) NaCl or from pH 5.0 to 8.5 or at 50 degree C. This ribonuclease degrades uracil containing nucleic acids only. Our isolate could be a novel renewable source of DNase free RNase enzyme.