벼(Orysa sativa L.) 뿌리로부터 분리된 내생 Streptomyces 균주의 동정 및 특성 = Identification and Characterization of an Endophytic Strain of Streptomyces from Rice Roots (Orysa sativa L.)

국문 초록 (Abstract)

천안의 단국대학교 근처에서 채취된 벼 뿌리로부터 내생 방선균 한 주를 분리 동정하였다. 표면 살균된 벼 뿌리를 분리 배지 위에 올려 놓고 배양하면 4주 후에 뿌리 표면에 형성된 방선균 콜로니를 볼 수 있었다. 이 중에서 한 균주 JK-5를 분리하여 동정하였다. 16S rDNA 염기서열을 확인한 결과 이 분리균주 JK-5는 Streptomyces diastaticus subsp. ardesiacus와 동일한 균주였다. 형태학적 관찰과 화학분류학적 결과에 의해 분리균주 JK-5의 분류학적 위치를 확인하였다. 기중균사의 형태는 flexible하며 포자사슬은 타원형의 약 30개 정도의 매끄러운 포자로 이루어 졌다. 세포벽은 L,L-diaminopimelic acid를 포함하고 있었다. 당 분석에서는 특이적인 당이 발견되지 않았다. 지방산으로는 anteiso-15:0, anteiso-17:0, iso-16:0 가 주요 성분이었다. 퀴논 분석결과 MK-9 ($H_6$)와 MK-9 ($H_8$)이 주요 성분으로 나타났다. GC 함량은 72%로 측정되었다. 식물병원성 곰팡이에 대하여 비교적 높은 항진균활성을 보여 주었다. 벼에 감염된 분리균주 JK-5가 뿌리와 줄기에서 균사체를 형성하며 왕성하게 생장하는 것을 SEM을 통하여 확인하였다.

다국어 초록 (Multilingual Abstract)

We isolated an endophytic actionmycete from root tissues of rice plant collected from paddy field near Dankook University, Cheonan, Korea. Surface sterilized roots were laid on the selective agar plates and incubated. The powdery actinomycete colonies appeared on the root surface after four weeks incubation. We isolated a strain JK-5 among them and could determine its taxonomical position as Streptomyces diastaticus subsp. ardesiacus by using 16S ribosomal DNA sequencing. The chemotaxonomical and morphological studies confirmed the taxonomical position of the strain JK-5. The shape of aerial hyphae was flexible and they contained spore chains with more than 30 smooth spherical spores per chain. Cell walls contained LL-diaminopimelic acid. There was no characteristic sugar in whole-cell hydrolysates. The major fatty acids were anteiso-15:0, anteiso-17:0 and iso-16:0. The specific menaquinones, MK-9 ($H_6$), MK-9 ($H_8$), were detected. The GC content was 72%. Antifungal activities of the strain JK-5 were relatively strong against fungal plant pathogens. The endophytic growth of the strain JK-5 was confirmed by SEM observation of the root and stem of the infected rice plant.

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