This study tested air- and argon-generated plasma-activated water against vegetative Paenibacillus larvae, the cause of American foulbrood. Both formulations damaged bacterial membranes, reduced culturability and improved larval survival in an infection model. Resistant spores and field effectiveness in colonies were not established.
Key findings
- PAW-Air contained 100-1,000 mg/L nitrate and 50-600 mg/L nitrite, while PAW-Argon contained 30-150 mg/L hydrogen peroxide. Both reduced culturable counts to roughly 4.54-4.74 log CFU/mL and relative membrane integrity to 35.87-37.47%. No colonies were detected in PAW-Air larval groups, and PAW-Argon yielded 1.11 ± 0.67 CFU/larva. Survival reached 59.38-60.42%, versus 43.23% in untreated infected controls.
Why this matters globally
American foulbrood is a major global apiculture threat, and antibiotic use is constrained. A non-antibiotic antimicrobial approach is attractive, but application requires evidence against spores and assurance of safety for bees, hive products and resident microbiota.
Thai researcher contribution
Maejo University and Chiang Mai University combined plasma technology with bee biology and protection, building a platform relevant to pollination security and apiculture.
Limitations to consider
The experiments targeted vegetative cells rather than the hardy, transmissible spores. A controlled larval model does not represent a colony. Long-term effects on bee development, commensal microbes and residues were not established, and reduced culturability does not necessarily equal complete eradication.