Community analysis of aggregated bacteria in southern Lake Baikal

概要

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The main aim of this study is to unveiling the community structure of aggregated bacteria in lake Baikal and determining the relations with free-living bacteria. For achieving this aim, FISH method was applied to free-living and aggregated bacteria in Lake Baikal at April, 2001. Bacterial counts of free-living bacteria by DAPI staining ranged from 0.2×10⁶ to 3.2×10⁶ cells·ml⁻¹, which decreased with depths, whereas aggregated bacterial numbers dramatically increased with depths, ranged from 0.4×10⁴ to 3.3×10⁴ cells·ml⁻¹. Also, the ratios of EUB probe binding cells to DAPI counts ranged from 52.3 to 74.1% in free-living bacteria, from 39.6 to 66.7% in aggregated bacteria, respectively. Community composition of aggregated bacteria was very different from free-livng bacteria. Especially, that is remarked at 25m depth which is observed the highest value phytoplankton. The vertical profile of aggregated bacteria community was very particular. β-Proteobacteria was increasing with depth till 100m. In 250m depth, γ-Proteobacteria was 44% of DAPI bound cells, while other groups were less than 1%. In conclusion, the bacterial community structures of free-living and aggregated bacteria were very different, and they sustain the independent ecosystem separately.
信州大学の論文
2004-02-28