초록
Cyanobacteria와 방선균에 의해 생산되는 대표적 취기물질인 geosmin의 정성 및 정량 분석법을 확립하고, cyanobacteria인 Phormidium sp. NIVA-CYA7의 생장과 geosmin의 생산 및 방출에 영향을 주는 환경요인에 대해 조사하였다. Geosmin의 분석은 전처리과정이 간편하고, purge 시간을 1시간으로 단축한 purge & trap concentrator가 장착된 gas chromatograph로 분석하였다. Phomidium의 생장은 pH 7.9, 온도 $20^{\circ}C$, 광도 120-140 $\mu$E/ $m^(2)$/s, Z8 배지의 배양조건에서 8일까지 유도기를, 이후 14일까지 지수성장기를, 14일 이후에는 정상기를 보였다. 배지내 질소의 농도를 250 $\mu$M에서 100 또는 25 $\mu$M로 감소시켰을 때, Phormidium의 생장은 거의 영향을 받지 않았다. 반면에 배지의 인 농도를 25 $\mu$M에서 10 또는 2.5 $\mu$M로 감소시켰을 때, 인의 농도가 감소할수록 생장은 억제되었다. 배지내 인의 농도를 25 $\mu$M에서 10 $\mu$M로 감소시켰을 때, 단위 탄소당 또는 엽록소-$\alpha$당 geosmin의 함량은 각각 35%와 68% 증가하였다. Phormidium의 geosmin함량은 pH 9.4에서 0.0824 $\mu$g/mg C로 pH 6,4m 7.9에 비해 두 배 이상 많았다. 따라서 Phormidium의 geosmin 함량은 생장단계, 인의 농도, pH등에 따라 영향을 받지만, geosmin의 방출은 이들 요인에 의하여 크게 영향받지 않는 것으로 판단된다.
A method for quantitative and qualitative analysis of geosmin, odorant produced by several actinomycetes and cyanobacteria, was established and optimized. The effects of environmental conditions on the growth of Phormidium sp. NIVA-CYA7 were examined and the production and release of geosmin by the species was analyzed by using the purge and trap-gas chromatographic technique. One of the major advantages of the technique established in the present study is that the preparation of sample is simpler and purge time is shorter. Under the culture conditions (pH 7.9, $20^{\circ}C$, 120-140 $\mu$E/$m^2$/s and Z8 medium), Phormidium showed growth characteristics with a lag phase for 8 days and an exponential phase for 14 days followed by a stationary phase. Reduction of inorganic nitrogen concentrations in the culture medium from 250 to 100 or 25 $\mu$M brought no significant effect on the cell growth. However, the cell growth was significantly inhibited with decreasing concentrations of inorganic phosphorus from 25 to 10 or 2.5 $\mu$M. When the inorganic phosphorus concentration in the medium was lowered from 25 to 10 $\mu$M, the levels of geosmin in the organism expressed as percentages per unit TOC and chlorophyII-$\alpha$ increased by 35% and 68%, respectively. When the initial pH of the medium was 9.4, geosmin content was 0.0824 $\mu$g/mg C, which was 2-fold higher than that at pH 7.9 Consequently, the level of geosmin in Phormidium was found to vary with growth phases of the culture, external inorganic phosphorus concentration and external pH, while the release of geosmin was not significantly affected by the factors.
