Abstract: In order to under the function of the microbial community in fermented soybean paste, we established a metaproteomic expression profile by stepwise extraction and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The proteins extracted were identified by liquid chromatography tandem mass spectrometry-mass spectrometry (LC-MS/MS). Results obtained were as follows: the number of proteins identified in fermented soybean paste was 232, including 60 proteins participating in sugar metabolism, 57 proteins involved in nucleic acid metabolism, 48 proteins involved in metabolism, 15 proteins related to energy metabolism, 3 proteins related to lipid metabolism and 49 other functional proteins. The number of proteins derived from bacteria was almost three times as large as the number of proteins derived from fungi. Bacterial proteins were mainly derived from Bacillus subtilis, Leuconostoc, Fecal streptococcus, Leuconostoc mesenteroides and Deshi Lactobacillus, while fungal proteins mainly came from Saccharomyces cerevisiae, Fission yeast, Alternaria, white rot fungi and Ashbya gossypii.

Key words: fermented soybean paste, metaproteomics, protein function, microbiota