Characterization of the Bacillus cereus spore killed by plasma-activated water (PAW)

Abstract

Bacillus cereus (B. cereus) spore is one of the most easily contaminated bacterial spores. Plasma-activated water (PAW) has emerged as a potential method for microbial inactivation. The exterior pyridine-2,6-dicarboxylic acid (DPA) of spores was released after PAW oxidative stresses. The broken inner membrane and partially hydrolyzed cortex were represented. Some spores’ architecture changed from a full and plump surface to these with wrinkles and indentations and even the shape shifted from oval to partly elongated irregular contraction. The detached exosporium, the devoid content, and the distinctly ruptured multilayer structure were exhibited. Young’s modulus indicated that PAW may cause a body with reduced elasticity. The multiple resistances toward NaClO, NaCl, heat, UV, H2O2, and lysozyme uncovered that the compromise in the spore coat, the loss of the integrity of inner membrane permeability, the denatured proteins, the unsaturated DNA, the degradation of α/β-type small acid-soluble proteins (SASPs) and part inactivation of cortex lytic enzymes occurred. The changes in fatty acid compositions, lipid peroxidation, protein loss, and the inhibited activity of ATPase as well as the degraded and collapsed representative DNA/DPA/proteins Raman spectrum peaks also further confirmed the potential sites for spore death by PAW.