Odorous compounds from a cyanobacterium in a water purification plant in central Taiwan

Microorganisms that rapidly proliferated as brown granules and attached to the walls of a storage vessel in a municipal plant for water purification were cultured in the laboratory. From the cultured broth a distinctly offensive odor was detected and filamentous organisms were found predominant. The objectives of this work were to isolate and identify the odor-producing microorganisms and analyze the odorous compounds. An actinomycete, which was not responsible for the production of odor, was found to coexist with the target bacterium, the cyanobacterium. However, a pure culture of cyanobacterium could not be obtained despite a series of purifications. According to morphological characteristics, the cyanobacterium was identified as Nostoc sp. With closed-loop stripping analysis (CLSA), trace organic of odorous compound produced by the isolate were detected at nanogram-per-liter levels. In a batch system, geosmin and MIB showed the highest concentration when cells were in the declining phase. Nostoc sp. was never reported to produce geosmin and MIB.