{"doi":"10.1016/j.bioflm.2025.100313","title":"Potassium iodide enhances the antimicrobial activity of plasma-activated water","abstract":"Plasma-activated water (PAW) is a promising disinfection strategy that generates a complex mixture of reactive oxygen and nitrogen species (ROS/RNS), including hydrogen peroxide (H 2 O 2 ), nitrate (NO 3 - ), and transient oxidants, in an acidic aqueous environment. These reactive species contribute to both immediate and extended antimicrobial activity. This study investigates how the addition of low concentrations (<100 μM) of potassium iodide (KI) enhances the bactericidal properties of spark-generated PAW by enabling the in-situ generation of reactive iodine species (RIS), particularly hypoiodous acid (HIO), under acidic conditions. KI addition (10–100 μM) led to a counterintuitive, dose-dependent increase in H 2 O 2 concentrations, from ∼1.2 mM in PAW alone to ∼1.8 mM at 30 μM KI, possibly due to iodine-mediated catalytic effects or reduced H 2 O 2 degradation. NO 3 - levels also increased by ∼17% with increasing KI. Equivalent concentrations of H 2 O 2 + KI failed to replicate the rapid antimicrobial activity observed in PAW + KI, which achieved complete inactivation of Escherichia coli and Listeria monocytogenes planktonic cells within 3 min, compared to over 10 min for PAW alone, indicating the involvement of additional reactive species in KI-enhanced antimicrobial activity of PAW. However, Salmonella enterica planktonic cells exhibited only partial inactivation even with KI, indicating species-specific tolerance under these conditions. 24h biofilms of L. monocytogenes and E. coli were eradicated with PAW + KI in 10 min, whereas S. enterica showed only a 2-log reduction. Scavenger assays revealed that both longer-lived species (H 2 O 2 ) and shorter-lived oxidants such as singlet oxygen are essential for this enhanced killing, while ozone and superoxide appeared dispensable. These findings support a multi-step antimicrobial mechanism: (1) plasma treatment creates a low pH, H 2 O 2 -rich solution; (2) iodide is oxidised to RIS such as I 3 - and HIO; (3) additional PAW-derived oxidants potentiate RIS chemistry; and (4) unionised HIO diffuses across bacterial membranes to induce oxidative damage. PAW-KI remained stable for at least 14 days at 4°C, with sustained RIS activity and minimal loss of H 2 O 2 or NO 3 - , suggesting preserved antimicrobial capacity over time. The antimicrobial mechanism likely proceeds through a four-step pathway: plasma-mediated generation of H 2 O 2 and NO 3 - ; oxidation of I - to I 2 and HIO; potentiation of RIS via PAW-derived ROS/RNS; and subsequent microbial inactivation via membrane damage. Together, these results demonstrate that PAW + KI forms a powerful, in situ RIS-generating system, offering a residue-minimising and environmentally sustainable disinfection platform. Its rapid action, scalability, and reliance on only air, water, electricity, and GRAS-listed KI make it an attractive intervention for food safety, clinical disinfection, and decentralised sanitation settings.","journal":"Biofilm","year":2025,"id":524259,"datarank":0.26876392038420827,"base_score":1.791759469228055,"endowment":1.791759469228055,"self_citation_contribution":0.26876392038420827,"citation_network_contribution":0.0,"self_endowment_contribution":0.26876392038420827,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":5,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9613,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2025-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":435465,"name":"Thomas P. Thompson","orcid":"0000-0001-8125-2303","position":1,"is_corresponding":false},{"id":1398326,"name":"Akash Shambharkar","orcid":null,"position":2,"is_corresponding":false},{"id":42587,"name":"Ross Duncan","orcid":"0009-0003-7502-1279","position":3,"is_corresponding":false},{"id":764411,"name":"Paula Bourke","orcid":"0000-0002-5607-8021","position":4,"is_corresponding":false},{"id":1030727,"name":"Timofey Skvortsov","orcid":"0000-0002-4048-6725","position":5,"is_corresponding":false},{"id":435468,"name":"Brendan Gilmore","orcid":"0000-0001-7675-9062","position":6,"is_corresponding":false},{"id":1219879,"name":"Laura A McClenaghan","orcid":null,"position":0,"is_corresponding":true}],"reference_count":36,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T02:50:12.083054Z","pmid":"40978334","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}