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Reproductive brown granules were found attached on the walls of
the storage in the Fong-Yuan Water Purifi-cation Plant. A
filamentous cyanobacterium was pre-dominated after culture. The
filamentous cyanobacterium contributed a very distinct and
offensive noisome odor. The objective of this study was to
investigate the odor-causing cyanobacterium. The study included
identifi-cation of cyanobacterium and analysis of odor-causing
organic compounds by closed-loop stripping analysis (CLSA)
using makeshift apparatus. Finally, this study investigated the
influence of two environmental factors- -temperature and light
intensity-on odorous compounds production by cyanobacterium
cells. After a series of isolation, purification, got a single
cyanobacterium, however, an actinomycetes stillexisted in the
culture. Evidently, this actinomycetesfailed to produce the
characteristic noisome odor.Therefore, it was the
cyanobacterium that produced odorin culture. The
cyanobactirium was Nostoc sp. onmorphological and physiological
characteristics. With CLSA, trace organics could be detected
at low nanogram-per-liter levels , detection limit of geosmin
and MIBwere 2.6 ng/l and 95 ng/l, respectively. Nostoc sp.
wasabundant at high temperature orunder light intensity ofover
2,000 lux. In batch culture, intracellular geosminand MIB were
produced and released during decay phase. Nostoc sp. produced
more odorous compound content(geosminand MIB) in terms of dry
cell weight underunsuitable growthcondit ions. This phenomenon
agreedwith results of previous studieson Anabaena sp.
andOscillatoria sp., which produce geosmin.
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