A Detection of Airborne Particles Carrying Viable Bacteria in an Urban Atmosphere of Japan

Abstract

Viable bacteria on water-insoluble airborne particles were detected in the urban atmosphere of Kumamoto (134°45′E, 32°28′N), Japan, in autumn 2008. Airborne particles were collected onto film-covered Cu meshes under clear weather conditions. The samples were stained by fluorescent stains, and then viewed and photographed with an epifluorescent microscope. Non-biological and bacterial parts in particles larger than 0.8 μm were distinguished by their morphologies, fluorescent colors and fluorescent intensities. Bacterial viable statuses were discriminated according to cell membrane damage. In total, 2681 particles were investigated and it was found that 78 airborne particles were associated with bacteria. Viable bacteria were identified on 48 particles. A few particles carried multiple viable bacteria. These results provide the evidence that airborne particles act as carriers of viable bacteria in the atmosphere.

Keywords

• biological particle
• viable bacteria
• airborne particle
• fluorescent staining
• urban atmosphere