농업 재배지 토양으로부터 auxin 생성세균 KSD16, KSD33 그리고 KSD36를 분리하였다. 분리 균주 KSD16, KSD33 그리고 KSD36 는 16S rRNA 유전자 계통분석을 통해 Arthrobacter 속으로 분류되 었다. 이들 균주는 R2A배지에 0.1% L-tryptophan를 첨가한 배지에서 28℃, 48 시간 배양한 결과, auxin 의 일종인 indole-3-acetic acid (IAA)를 204.4 mg L-1 생성하는 것으로 확인되었다. IAA 생성세균의 녹 두종자 발아에 미치는 영향을 확인한 결과, Arthrobacter 속 균주 KSD16, KSD33 그리고 KSD36 는 대조 군에 비해 뿌리길이와 발근수가 증가하였다. Arthrobacter 속 균주의 녹두 성장촉진 효과를 확인한 결과, 녹두의 발아율이 대조군보다 73.4 % 증가하는 특징을 나타내었다.

Background : Panax ginseng is an important crop based on its pharmaceutical efficacy in the Asian countries, it cultivated in Korea is usually harvested after 4 to 6 years of cultivation, whereas various abiotic stresses lead to a reduction of its quality. One of them is the Aluminum (Al) accumulation. Plant growth promoting rhizobacteria (PGPR) can play a role in plant health and growth and has been considered as a new trend for supporting the growth of many crops in heavy metal occupied areas. Accordingly, this study aimed to utilize PGPR to enhance the resistance of the ginseng plant against Al stress. Methods and Results : The screening of several PGPR isolated from ginseng cultivate soil had been carried out by in vitro and in planta studies to confirm the plant growth promoting traits. Amongst, the strain Rhizobium panacihumi DCY116T was registered as one novel bacteria species and found to have IAA, siderophores production and phosphate solubilization traits, heavy metal resistance activity, and antifungal activity by in vitro test. Furthermore, in the perennial plant ginseng, fifteen minutes dipping of 108 CFU/㎖ DCY116T was enough to prime 1.5-years-old ginseng seedlings against given Al stress. Ginseng seedlings treated with DCY116T showed higher biomass, active compounds (like ginsenoside, proline, total phenolic, sugars) than non-bacterized Al-stressed seedlings. DCY116T treatment induced Al stress related genes, ROS scavenging genes, ABA biosynthesis genes and root hair formation genes which prevent the Al stress. Conclusion : R. panacihumi DCY116T can be used to prime ginseng seedlings and induced its Al resistance. Also, it can promote the root hair formation. Based on these results, strain DCY116T can be as a potential plant growth promoting bacterium used in the future for the cultivation of ginseng or other kind of crop/ plant growth under Al stress.

This study was conducted to isolate and characterize a novel feather-degrading bacterium producing keratinase activity. A strain K9 was isolated from soil at poultry farm and identified as Xanthomonas sp. K9 by phenotypic characters and 16S rRNA gene analysis. The cultural conditions for the keratinase production were 0.3% fructose, 0.1% gelatin, 0.04% K2HPO4, 0.06% KH2PO4, 0.05% NaCl and 0.01% FeSO4 with an initial pH 8.0 at 30℃ and 200 rpm. In an optimized medium containing 0.1% chicken feather, production yield of keratinase was approximately 8-fold higher than the yield in basal medium. The strain K9 effectively degraded chicken feather meal (67%) and duck feather (54%), whereas human nail and human hair showed relatively low degradation rates (13-22%). Total free amino acid concentration in the cell-free supernatant was about 25.799 mg/l. Feather hydrolysate produced by the strain K9 stimulated growth of red pepper, indicating Xanthomonas sp. K9 could be not only used to increase the nutritional value of chicken feather but also a potential candidate for the development of natural fertilizer applicable to crop plant soil.