Comparative proteomic analysis of antagonistic Bacillus amyloliquefaciens Q-426 cultivated under different pH conditions.

Bacillus amyloliquefaciens Q-426 produces lipopeptide compounds with antifungal activities. Initial pH value has a significant influence on the production of lipopeptide compounds. The correlation between pH and intrinsic mechanism of lipopeptide production was rarely discussed. In this research, comparative proteomics, using two-dimensional gel electrophoresis and mass spectrometry, was applied to identify B. amyloliquefaciens Q-426 intracellular proteins differentially expressed under initial pH 5.0 and 7.3. A total of 24 differential spots (eight downregulated and 16 upregulated) under pH 5.0 were identified. Certain proteins were involved in the regulation of bacillomycin and fengycin production by B. amyloliquefaciens Q-426. These proteins include four induced proteins related to stress response: Thiamine pyrophosphate-dependent acetoin dehydrogenase, butanediol dehydrogenase, two ABC-type oligopeptide transport system proteins, and two-component response regulator DegU and chorismate mutase PheB. These results indicate intrinsic differences of antagonistic B. amyloliquefaciens Q-426 under different pH conditions.