Abstract:The protoplast of Pseudomonas sp. BS1 was transformed by temperature-sensitive plasmid pTV1-OK that harbor Tn917. 3 stable transformants were obtained from the LB plates with Kan and Erm. Lots of mutants were obtained by transposon mutagenesis of Tn917, sequencely a mutant library was constructed. A predicted fragment was amplified by PCR from 5 randomly selected mutants, which showed that Tn917 successful inserted into the genome of Pseudomonas sp. BS1. E24 of a mutant from 24 selected randomly reach up 67% by the measurement of the emulsification index, significantly higher than wild-type strain. These results indicated that the transposon mutagenesis is an effective method for obtaining high-producing biosurfactant.