title: The effect of negative air ion exposure on Escherichia coli and Pseudomonas fluorescens.
abstract: Antibacterial activity of negative air ions (NAI) on Escherichia coli and Pseudomonas fluorescens has been investigated. Appropriately diluted cell suspensions of E. coli and P. fluorescens were inoculated onto agar and exposed to NAI (> 2 x 10(6) ions/cm(3)) in an airtight chamber. Although no bacterial killing was observed after short exposure (15-30 min), longer exposure upto 4 hours caused 33% and 42% reduction in viability of E. coli and P. fluorescens, respectively. Maximum killing was observed when the plates were positioned in front of the NAI generator. Young exponential phase cells of P. fluorescens were more resistant (8% reduction in viability) as compared to stationary phase cells (42% reduction in viability). Also, the starved cells displayed less reduction in viability (33%) as compared to normal cells (42%). The susceptibility of bacterial strains to NAI varies depending upon the strain type, their physiological state as well as the distance/orientation with respect to the source. Although application of NAI for decreasing the ambient microbial load is a valid option; extended exposures might be required for controlling physiologically different cells such as exponential phase cells and/or starved cells.
authors.affiliation: Center for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi, India.
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Tyagi
authors.forename: Bikesh Kumar
authors.initials: BK
authors.lastname: Nirala
authors.forename: Anushree
authors.initials: A
authors.lastname: Malik
authors.forename: Kamlesh
authors.initials: K
authors.lastname: Singh
mesh_terms: D000390:Air Ionization; D000393:Air Pollutants / Q000737:chemistry / Q000633:toxicity*; D000838:Anions / Q000737:chemistry / Q000633:toxicity; D000900:Anti-Bacterial Agents / Q000633:toxicity; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development; D050296:Microbial Viability / Q000187:drug effects; D011551:Pseudomonas fluorescens / Q000187:drug effects* / Q000254:growth & development; D013997:Time Factors
chemical_list: D000393:Air Pollutants; D000838:Anions; D000900:Anti-Bacterial Agents