| Co-Investigator(Kenkyū-buntansha) |
DAIMON Hiroyuki Toyohashi University of Technology, Department of Ecological Engineering, Associate professor, 工学部, 助手 (60335106)
FUJIE Koichi Toyohashi University of Technology, Department of Ecological Engineering, Professor, 工学部, 助教授 (30134836)
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| Research Abstract |
Natural aquatic ecosystems such as lakes, ponds, and rivers are composed of numerous kinds of microorganisms. Among the microorganisms, bacteria play a crucial role in transformations of most nutrients, organic matter and energy flux in aquatic ecosystem. Utilization of dissolved organic matter by heterotrophic bacteria constitutes a major link in the energy flow of aquatic ecosystem. Biomass concentration and microbial community structure are important factors controlling the capacity to degrade organic compounds (pollutants) in the ecosystem. Biomass is an important parameter because it measures the quantity of energy being stored at certain trophic levels within a biological community. In recent years, the technique of using quinone profiles has gained increased recognition as a simple and useful tool for the analysis of microbial population dynamics in mixed cultures.
In this study, the technique of quinone profiles was applied to clarify the change in microbial community structure
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and identifying diurnal change in community structure of suspended microorganisms. The microbial community structures in surface water of 11 ponds, 4 rivers and 3 tidal flats were characterized and compared by analyzing the compositions of respiratory and photosynthetic quinones (ubiquinone (UQ), menaquinone (MK), plastoquinone (PQ) vitamin K1 (VK1 )).
The dominant quinone species in river-suspended microorganisms was UQ and MK, and that in pond-suspended microorganism and riverbed-attached microorganisms was PQ-9 and VK1. This indicates that heterotrophic bacteria were abundant in the river suspended microorganisms, but photosynthetic microorganisms such as micro-algae and cyanobacteria dominated the pond suspended bacteria and the riverbed attached microorganisms. Concentration of respiratory quinones (Uqs and MKs) in the surface waters increased linearly with high BOD.
The comparison of microbial community structure in other environments such as soils and activated sludges are enabled by analyzing of quinone profile in these natural aquatic ecosystems. Less
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