Abstract:Abstract: [Object] We investigated the proteomic profile of Lactobacillus brevis NCL912 under optimum pH and acidic pH in the media without the addition of sodium L- glutamate to characterize the differential expression proteins and function by two-dimensional gel electrophoresis. [Methods] The differential expression proteins were separated and analyzed by two-dimensional gel electrophoresis, mass spectrum and bioinformatics. [Results] The results showed that the two-dimensional gel electrophoresis profiles of L. brevis NCL912 were uniformity, well-resolution and repeatability. 25 proteins were differently expressed in the two profiles. Among them, 8 proteins were identified and analyzed by the mass spectrum and bioinformatics due to the lack of genome sequence data of L. brevis NCL912. These proteins played the roles of the synthesis of protein and DNA, glycolysis and regulating the cellular energy level. [Conclusion] The differential expression proteins might play the important role in the acid stress resistance mechanism which may protect cell against acid stress.