S. agalactiae NSGC54 culture in logarithmic growth phase was added GA (15:1) to a final concentration of 3.125μM and control group treated with dmso. RIPA lysis buffer was used to lyse the collected protein solution. The total protein concentration of the cell lysate was measured by the BCA kit (Beyotime Biotechnology, Shanghai, China). The cell lysate was incubated with dmso and GA (15:1) at 4 °C for 30 minutes, and the protease K was added at a mass ratio of 1:500 for digestion at room temperature for 30 minutes. The loading buffer was added to terminate the digestion and the water bath was heated at 70 °C for 10 minutes. Finally, differential proteins were identified by mass spectrometry and bioinformatics analysis.