Characterization of a Novel Esterase Belonging to Family V from Marinobacter flavimaris

Lipolytic enzymes have attracted enormous attentions because of their ability in ester hydrolysis, ester synthesis, trans-esterification and other biochemical reactions. Bacteria are important sources of lipolytic enzymes applied in industry. Here, a novel lipolytic enzyme encoded by esterase gene est1347 was identified in Marinobacter flavimaris WLL162, and was purified and characterized. The lipolytic enzyme Est1347 consisted of 312 amino acid residues and a 21-amino-acids N-terminal signal peptide with a predicted molecular weight of 34.2 kDa. It belongs to family V of bacterial lipolytic enzymes based on the amino acid sequence homology analysis. Est1347 is a mesophilic and alkali-resistant enzyme with the highest activity at 45°C and pH 8.5; it is stable at temperatures below 50°C and pH 7.5–11.0. Est1347 showed a preference for middle-length chain substrate p-NPC10 and a wide range of other substrates. The K_m, V_max, K_cat and K_cat/K_m values of Est1347 for p-NPC10 in pH 8.5 at 45°C were 0.9411 mmol L⁻¹, 1285 µmol min⁻¹ mg⁻¹, 698.91 s⁻¹ and 743.65 s⁻¹ (mmol L⁻¹)⁻¹, respectively. It is also tolerant to the metal ions, organic solvents and detergents. In conclusion, the esterase Est1347 laid a foundation for further study of bacterial lipolytic enzyme family V.