Combined antimicrobial effect of plasma-activated water and mild heat against Penicillium expansum spores
Yunfang Ma, Yanqing Ma, Wenjie Gong, Lei Chi, Qisen Xiang
Abstract
This study aimed to examine the combined antimicrobial action of plasma-activated water (PAW) and mild heat (30, 40, 50, and 60 °C) against Penicillium expansum spores in phosphate-buffered saline (PBS). The combined treatment showed stronger antimicrobial activity against P. expansum spores. P. expansum spores decreased more than 6.76 log 10 CFU/mL after exposure to PAW at 60 °C for 10 min, which was higher than that of samples treated by PAW at 25 °C (0.80-log reduction) or mild heat treatment alone at 60 °C (2.27-log reduction). After exposure to PAW + mild heat, a high amount of intracellular nucleic acids and proteins were released from spores, suggesting the loss of cell membrane integrity. P. expansum spores also exhibited a large increase in intracellular reactive oxygen species (ROS) and a reduction in mitochondrial membrane potential after exposure to PAW + mild heat. Moreover, antioxidants glutathione and N-acetylcysteine effectively inhibited spores death induced by PAW + mild heat, suggesting that ROS was involved in the antifungal action of PAW and mild heat. In summary, PAW + mild heat exhibits excellent antimicrobial activity against P. expansum spores by destroying cellular membranes, reducing mitochondrial membrane potential, and causing oxidative damage. • PAW +60 °C showed synergistic antimicrobial effect against P. expansum spores. • Combination of PAW and mild heat enhanced cell membrane disruption. • ROS played an important role in the synergistic antimicrobial action. • PAW + mild disrupted mitochondrial membrane potential of P. expansum spores.