Optimization of urease production by Bacillus halodurans PO15: a mangrove bacterium from Poovar mangroves, India

Abstract

Mangrove ecosystems are one of the most versatile habitats for microorganisms with a high potential for producing a variety of extracellular hydrolytic enzymes. In this study, bacteria with urease activity, enzymes that catalyze the hydrolysis of urea into carbon dioxide and ammonia, were isolated from mangrove sediments of Poovar (Trivandrum, India). Bacillus halodurans, strain PO15, isolated in this study with high urease (UA) activity (28 U/ml) was subjected to optimization using a Box-Behnken experimental design. Incubation variables included incubation period, pH, inoculation percentage and temperature. Significant factors identified based on the model were incubation period, pH, incubation temperature, and inoculum percentage; variations in these produced a tenfold increase in UA activity (295.80 U/ml). The specific activity of the purified UA enzyme was 62.34 U/mg and was found to be thermostable (active up to 60 °C). UA of B. halodurans PO15 has potential for microbial-induced biomineralization with a reduction of free Ca²⁺ to about 82.8% ± 0.17%. The microbial-induced calcium precipitation (MICP) using the UA enzyme will potentially be beneficial in the process of biomineralization as well as for a variety of industrial applications.