Abstract
- The purpose of this work is to investigate the effects of various substrates on biosynthesis of ethylene by the Kudzu strain of Pseudomonas syn'ngae pv. Phaseolicola causing halo blight. In the intact cell of P. sym'ngue, optimal condition for ethylene production was achieved at p1-I 7.5 and $30^{\circ}C$ for 9 to 10 hours of culture. Ethylene was most effectively produced from amino acids such as Asn, Gln, Asp ans Glu, compared to those of various kinds of sugars. While ethylene production from $\alpha$-ketoglutarate ($\alpha$-KG) was gradually increased throughout 51 hours incubation period tested. Ethylene production derived from citrate, $\alpha$-KG and oxalacetate as well as a few amino acids was further enhanced by the addition of histidine or arginine. In cell-free ethylene-forming system, ethylene was most effectively produced from $\alpha$-KG, compared to those from citrate, oxalacetate, Glu, Arg, or Asp, at 0.5 mM among the range from 0.25 mM to 5 mM. Anlinooxyacetate, an inhibitor of a pyridoxal phosphate-linked enzyme, completely inhibited ethylene evolution derived from Glu but not affect that derived from $\alpha$-KG. The results obtained in this work suggest that $\alpha$-KG might be a direct precursor of ethylene production in this organism than any other substrates tested.
Pseudomonas syringae의 intact cell에서 에틸렌 생성을 극대화 하기 위한 전환조건은 $30^{\circ}C$. pH7.5로 조사되었고, 다양한 기질의 전환효과를 검초한 결과, Asn>Gln>Asp>Glu>$\alpha$-KG>citrate>oxalacetate의 순으로 많은양의 에틸렌을 생성하였다. 또한, arginine과 histidine을 상기 유기산과 함께 넣었을 때 에틸렌 생성에 현저한 상승효과를 나타냈다. Cell-free system 에서는 $\alpha$-KG>Glu>citrate>Gln>Ser순으로 0.5mM $\alpha$-KG에서 310.8(nl.mg $protein^[-1}.h^[-1}$)로 가장 많은 에틸렌을 생성하였고, aminotransferse 억제제인 AOA를 사용해 본 결과, Glu는 glutamate dehydrogenase에 의하여 $\alpha$-KG를 거쳐서 에틸렌으로 전환된 것이라 생각된다.