염기성 pH에서 Enterobacter amnigenus GG0461의 질산이온 흡수증가 = Enhanced Nitrate Uptake by Enterobacter amnigenus GG0461at Alkaline pH

다국어 초록 (Multilingual Abstract)

Salt accumulation in soils of greenhouse due to the massive application of nitrogen fertilizers causes
salt stress on the various crops, a serious problem in domestic agriculture. Since the majority of
the salinity is nitrate, the excess nitrate should be removed; therefore, a bacterial strain having
high capacity of nitrate uptake and identified as Enterobacter amnigenus GG0461 was isolated from
the soils of greenhouse. Optimum conditions for the bacterial growth and nitrate uptake were
investigated. GG0461 was able to grow without nitrate; however, nitrate facilitated the growth. The
rate of nitrate uptake increased at alkaline pH and both growth and nitrate uptake were maximal
at pH 8-9. When the initial pH of culture medium was increased to pH 8 or 9, it was decreased
to neutral upon bacterial growth and nitrate uptake. These results imply that the major factor
mediating bacterial nitrate uptake is a nitrate/proton antiporter. The fact was supported by the
effect of nitrate addition in the absence of nitrate, since the addition of nitrate greatly increased
the nitrate uptake and rapidly decreased pH of media.

국문 초록 (Abstract)

질소비료의 과량 시용에 따른 시설원예지 토양 중 염류집적은 다양한 작물에 염류장애를 유발하여 국내농업에 심각한 문제가 되고 있다. 염류의 주성분은 질산염으로 필요이상의 질산
이온을 제거하기 위하여 질산이온 흡수력이 크며, Enterobacter amnigenus GG0461로 동정된 토양세균을 시설원예 토양에서 분리하였다. 이 균주의 최적 생육 및 질산이온 흡수력을 조사하였을 때, GG0461 균주는 질산이온이 없는 조건에서 생육이 가능하나, 질산이온이 존재할 때 생육이 크게 촉진되었다. 또한, 염기성 조건에서 질산이온 흡수율이 증가하였으며, 성장과 질산이온 흡수 모두 pH 8-9에서 최대로 나타났다. 배지의 초기 pH를 8과 9로 조정하였을 때, 균주에 의하여 질산이온이 흡수
됨에 따라 배지의 pH는 중성으로 감소하였다. 이러한 결과는 질산이온 흡수를 위한 주된 인자가 nitrate/proton antiporter임을 의미한다. 이것은 질산이온이 없는 조건에서 질산이온의 첨가
효과인 질산이온 흡수의 급격한 증가와 빠른 배지의 pH 감소 사실로도 확인되었다.

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