Purification and biochemical characterization of a cold-active lipase from Antarctic sea ice bacteria Pseudoalteromonas sp. NJ 70

An extracellular cold-active lipase from Antarctic sea ice bacteria Pseudoalteromonas sp. NJ 70 was purified and characterized. The overall purification based on lipase activity was 27.5-fold with a yield of 25.4 %. The purified lipase showed as a single band on SDS-PAGE with an apparent molecular weight of 37 kDa. The optimum temperature and pH were 35 °C and 7.0, respectively. The lipase activity was enhanced by Ca²⁺ and Mg ²⁺, while was partially inhibited by other metals such as Cu ²⁺, Zn²⁺, Ba²⁺, Pb²⁺, Fe ²⁺ and Mn²⁺. The lipase had high tolerance to a wide range of NaCl concentrations (0-2 M NaCl). It exhibited high levels of activity in the presence of DTT, Thiourea, H₂O₂ as well as in the presence of various detergents such as Span 60, Tween-80, Triton X-100. In addition, the lipase showed a preference for long-chain p-nitrophenyl esters (C₁₂-C₁₈). These results indicated that this lipase could be a novel cold-active lipase.