The microbial communities transported by Asian desert dust (KOSA) events have attracted much attention as bioaerosols, because the transported microorganisms are thought to influence the downwind ecosystems in Japan. In particular, halotolerant bacteria which are known to be tolerant to atmospheric environmental stresses were investigated for clarifying the long-range transport of microorganisms by KOSA. Bioaerosol samples were collected at high altitudes within the KOSA source area (Dunhuang City, China) and the KOSA arrival area (Suzu City, Japan). The microorganisms in bioaerosol samples grew in media containing up to 15 % NaCl, suggesting that bacteria tolerant to high salinities would remain viable in the atmosphere. The PCR-DGGE (Denaturing gradient gel electrophoresis) analysis using 16S rRNA genes sequences revealed that the halobacterial communities in bioaerosol samples belonged to the members of the genera Bacillus and Staphylococcus and that some bacterial species belonging to Bacillus subtilis group were similar among the samples of both cities. Moreover, some sequences of B. subtilis group were found to be identical for the species collected at high altitudes and on the ground surfaces. This suggests that active mixing of the boundary layer transports viable halotolerant bacteria up to the free atmosphere at the KOSA source area, while down to the ground surface at the KOSA arrival areas.
