Proteomics Analyses and Morphological Structure of Bacillus subtilis Inactivated by Pulsed Magnetic Field

摘要

Pulsed magnetic field (PMF) technology has emerged as a non-thermal method for inhibition of spoilage microorganism in food. In this study, we evaluate the effect of PMF treatment on the inactivation of Bacillus subtilis. The mechanisms responsible for cell death were also studied using transmission electron microscopy (TEM) and proteome approaches. Results showed that the survival rate of B. subtilis generally decreased with an increase of pulse numbers at the intensity of 3.30 T. The observation of TEM showed damage in cell cytoplasm and cytoplasmic membrane after PMF treatment. Additionally, 18 differentially expressed protein spots were identified by two dimensional gel electrophoresis (2D-GE) and matrix-assisted laser desorption/ionization-time-of-flight/time-of-flight (MALDI-TOF/TOF) analysis. The down-regulated outer membrane protein A (OmpA) illustrated that PMF destroyed the cell membrane. Furthermore, Gene ontology (GO) analysis and kyoto encyclopedia of genes and genomes (KEGG) pathway analysis were used to characterize the functions of those proteins. That PMF treatment damaged the membrane component, depressed cellular molecular functions and biological process, and decreased the carbohydrate metabolism and energy metabolism, which explain the death of cells. The presented results give the better view into the proteome of food microorganism and provide insight into the nature of PMF inactivation mechanisms.