Catalytic properties and immobilization of enzyme preparations containing lipase of the haloalkalotolerant bacteria <i>Pseudomonas peli</i> and <i>Bacillus aequororis</i>

Abstract

In this work, we investigate the catalytic properties and immobilization of enzyme preparations containing lipase of haloalkalotolerant bacteria Pseudomonas peli and Bacillus aequororis. Lipase was isolated from the P. peli 3-T and B. aequororis 5-DB followed by its immobilization on either carboxymethylcellulose, activated chitosan or fodder yeast. The pH-dependence of native enzyme activity and thermostability, as well as the residual activity upon immobilization and drying of immobilized product, were determined. The lipase activity from both sources enhances with increasing alkalinity of the reaction medium. Specifically, P. peli 3-T lipase exhibited no activity in an acidic medium, and B. aequororis 5-DB lipase exhibited around 20% of maximum activity at a pH value of 6–7. The isolated lipase has a rather high thermostability; thus, P. peli 3-T lipase fully retains its initial activity upon heating to 60°C and 70°C for 1 h. Moreover, 15 min exposure to temperatures of 80°C and 90°C leads to an activity decrease of 73% and 83%, respectively. Activated chitosan and fodder yeast are the most promising of the studied excipients for enzyme immobilization. Drying of the immobilized lipase product on the activated chitosan showed retention of 3% and 46% of the native enzyme activity derived from P. peli 3-T and B. aequororis 5-DB, respectively. In the case of fodder yeast, these values were 2% and 64%, respectively.