Abstract:Two-dimensional electrophoresis(2-DE)had been employed to compare the global protein patterns between low transformability Bacillus subtilis BR151 pm and wild strain BR151 p,and 28 protein spots were found to express differentially.Two protein spots which re- markably unexpressed in B.subtilis BR151pm were measured by matrix assisted laser desorption/ionization tandem time-of-flight mass spec- trometry.With peptide mass fingerprinting,two protein spots were identified as Nin and RecA,which were directly involved in the develop-ment of natural competence in B.subtilis. The results determined that strain BR151pm was natural competence-deficient.