Anabaena variabilis ATCC 29413 의 생장과 질소고정활성의 조절요인

Factors Regulating the Nitrogen Fixation Activity and Growth of Anabaena variabilis ATCC 29413

광자가영양이며 질소고정는을 갖는 사상체의 남조 Anabaena variabilis ATCC 29413 Allen & Arnon (1/8) 의 무질소 최소배지에서 배양하여, 이형세포를 유도하고 생장과 질소고정활성의 변화와 각종 조절요인의 영향을 분석하였다. 질소결핍의 배지에서 생장과 질소고정활성의 증가율은 비례하였고, 생장에 따한 배지내 질산 ($NO^{3}$-N) 의 축적을 보였으며, 배양 6일 후에도 생장은 지속되었으나, 질소고정은 최대활성을 보인후 급격한 감소를 보여 질산의 저해농도와 일치하였다. 중요 환경요인의 영향은 혐기적 조건, 10,000 lux pH 8 및 $30^{\circ}C$ 에서 최적의 생장과 활성을 보였고, 질소화합물은 0.1 mM 이상의 저농도에서 현저히 활성을 저해하였으며, 탄산은 5 mM 에서 활성을 촉진하였으나 보다 높은 농도에서 저해를 보였다. 내염성을 NaCl 20mM 이하이었고 중금속이온은 $Hg^{2+}$>$Cd^{2+}$> $Co^{2+}$>$Zn^{2+}$>$Pb^{2+}$의 순으로 0.3~10 ppm 의 범위에서 활성을 저해하였다. 탄수화물은 0.5-1.0% 에서 생장과 활성을 촉진하였고, 설탕>과당>포도당의 순이었다.

Anabaena variabilis A TCC 29413. a photoautotrophic and nitrogen fixing cyanobacteria. was investigated on the environmental factors regulating the growth and nitrogen lixation activity. A good growth of cyanobacteria] cells was observed due to nitrogen t1xation by the heterocyst differentiation in nitrogen free Allen and Arnon (]/8) medium. The nitrogenase activity was appeared to be in proportion to the cell growth lor 6 days then drastically decreased in the later growth period when the nitraTe was accumulated to high level in the culture to cause the inhibition. The optima] conditions lilr the cell growth and nitrogenase activity of A. varillbili.l were anaerobic. IO.OO0 lux. $30^{\circ}C$ and pH 8 with the nitrogen Cree minimal medium. The activity was significantly inhihited by the low concentrations of ammonium and nitrate. but was stimulated b) the ]ow Ieve] of phosphate and carbonate sources. The treatments of several toxic heavy metals showed strong inhibition of the cell growth and nitrogenase activity by O.3~10 ppm in the order of $Hg^{2+}$ > $Cd^{2+}$ > $Co^{2+}$ > $Zn^{2+}$ > $Ph^{2+}$, and the concentrations for 50% inhibition of the maximum activity were 0.41. 0.47. 0.5 L 0.66 and 8.1 ppm. respectively. The addition of carbohydrates (0.5~ 1.0%) in the dark condition stimulated the growth and activity in the order of sucrose > fructose > glucose.