立山における黄砂を含む積雪層中の細菌群集

概要

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Asian dust particles transported from Asian desert areas are trapped in spring snow on the western plateau of Mt. Tateyama, Japan. We investigated bacterial communities in snow layers containing Asian dust, and other underlying snow layers, on Mt. Tateyama during 2008 and 2009. Several genera of bacteria were present among isolates obtained from Asian dust-containing snow layers, including the presumed dust-associated bacterial genus Bacillus. In particular, we detected isolates with identical 16S rDNA sequences (AB500941) over 2 consecutive years, and these isolates were most closely related to Bacillus subtilis. PCR-denaturing gradient gel electrophoresis (DGGE) analysis showed that bacterial community profiles in the Asian dust-containing snow layers were similar over the 2 years. The bacterial communities differed between the Asian dust-containing layers and other layers. Total bacterial cell counts ranged from 6.85×10⊃2; to 2.39×105 cells ml-1, with higher values in the Asian dust-containing layers than in the other layers. A backward trajectory analysis showed that the possible source of Asian dust was similar each year. The bacterial community composition of the Asian dust-containing layers presumably reflected the long-distance transportation of microorganisms from dust source regions.