Conclusions
The thermostability of B. licheniformis RSP-09 lipase was enhanced by two rounds of error-prone PCR mutagenesis. The results of the present study suggests that thermostability of lipases may be improved by various ways such as introduction of proline,increase of the surface charges, optimization of the surface charges,electrostatic potential and introduction of salt bridge formation.The enhanced thermostability also renders increased stability inorganic solvents. The stabilization of B. licheniformis RSP-09 lipaseand prolongation of its half-life with directed evolution withoutdecreasing its catalytic efficiency indicate that thermostabilizationusing this approach is very promising for broadening its indus-trial applications. Moreover, this study identifies the amino acidsimparting the thermostability to B. licheniformis lipase.