A team of researchers from the College of Food Science and Engineering at Henan University of Technology has made a significant advancement in the field of food safety by elucidating the sophisticated mechanism by which Dielectric Barrier Discharge Plasma (DBDP) inactivates harmful Aspergillus flavus spores. The study, recently published in the journal ‘Toxicon’, provides critical insights into how DBDP can effectively neutralize fungal threats in food without relying on traditional chemical methods, which have often been a source of concern among consumers and health professionals alike. This article offers an in-depth review of the research findings and their implications for the food industry.
Aspergillus flavus is a species of fungus that can contaminate a wide variety of food crops, posing a significant risk to public health and economies worldwide. It is known to produce aflatoxins, which are among the most potent carcinogens identified by science. Therefore, finding efficient and safe methods to deactivate A. flavus spores is an urgent priority in the food industry.
Dielectric Barrier Discharge Plasma (DBDP) technology is a novel food safety intervention based on using electrical discharge to generate plasma, a state of matter composed of a mixture of ions, electrons, and neutral molecules. DBDP operates at room temperature and has been recognized for its ability to inactivate a variety of microbial pathogens effectively. However, the precise mechanisms by which DBDP affects fungal spores have been a topic of ongoing research.
The research team, led by Wang Yaxin with key contributions from Yu Mingming, Xie Yanli, Li Xiao, and other colleagues, employed a multi-disciplinary approach to meticulously dissect the effects of DBDP treatment on Aspergillus flavus spores. Utilizing scanning electron microscopy (SEM), in vivo and in vitro experiments, transcriptomic analyses, and a host of physicochemical detection methods, they pieced together a comprehensive picture of the inactivation pathway affected by DBDP.
Upon just 30 seconds of DBDP treatment at 70 kV, the studies revealed a definitive inhibition of mycelium growth. SEM images clearly showed spore germination ceasing and tightly bound clusters forming, indicative of extensive membrane disruption and consequential release of cellular contents. These physical changes set off a chain reaction leading to spore death.
The transcriptomic data further substantiated these observations by suggesting a downregulation of genes associated with cellular components such as membranes and organelles, particularly mitochondria, oxidative phosphorylation, and the tricarboxylic acid cycle.
Corroborating with the transcriptomics, the researchers assessed the levels of enzymes integral to the metabolic pathways within the spores. The findings highlighted a dramatic decrease in crucial enzymes like superoxide dismutase, acetyl-CoA, total dehydrogenase, and ATP levels, mirroring the suppressed gene expression patterns noted earlier.
This significant drop in enzyme activity pointed towards mitochondrial dysfunction, a redox imbalance, and diminished energy metabolism pathways as critical effects of the DBDP treatment.
The researchers posited that reactive oxygen species (ROS), generated by the DBDP, played a pivotal role in triggering mitochondrial dysfunction, leading to a cascade of metabolic failures within the fungal spores. Remarkably, this inactivation path did not primarily hinge on the disintegration of cell membranes, as often seen with other antimicrobial treatments.
The implications of the study are far-reaching for food safety practices. By providing an alternative to chemical preservatives, DBDP stands as a promising tool for combating fungal contaminants in a variety of food matrices.
Moreover, the insights gathered from the study could pave the way for further innovations in crop protection and storage, reducing food losses and the economic burden associated with spoilage and mycotoxin contamination.
The study represents a critical milestone in our understanding of nonthermal plasma technology and its potential applications in safeguarding the global food supply.
References
1. Wang, Yaxin, et al. “Mechanism of inactivation of Aspergillus flavus spores by dielectric barrier discharge plasma.” Toxicon, vol. 239, 12 Jan. 2024, article no. 107615, 10.1016/j.toxicon.2024.107615.
2. Misra, N.N., et al. “Cold plasma for effective fungal and mycotoxin control in foods: Mechanisms, inactivation effects, and applications.” Comprehensive Reviews in Food Science and Food Safety, vol. 16, no. 6, 2017, pp. 1136-1156.
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5. Pankaj, S.K., et al. “Effect of cold plasma on food quality: A review.” Foods, vol. 7, no. 1, 2018, art. no. 4.
Keywords
1. Dielectric Barrier Discharge Plasma
2. Inactivation of Aspergillus flavus
3. Nonthermal food preservation
4. Mitochondrial dysfunction in fungi
5. Aflatoxin control in food
DOI: 10.1016/j.toxicon.2024.107615