• The Plant Pathology Journal
• /
• 제20권3호
• /
• pp.172-176
• /
• 2004

Bacterial isolates TRL2-3 and TRK2-2 showing anti-fungal activity in vitro test against some plant pathogens were identified as Pseudomonas putida and Micrococcus luteus, respectively. Pre-treatment with both bacterial isolates at the concentration 1.0$\times$ $10^7$ and $10^6$cfu/ml in the rhizosphere could trigger induced systemic resistance in the aerial part of cucumber plants against anthracnose caused by Colletotrichum orbiculare. However, the pre-treatment with the higher concentration at 1.0 $\times$ $10^8$ cfu/ml of both isolates could not induce resistance after challenge inoculation with C. orbiculare. As a positive control, the treatment with DL-3 amino butyric acid caused a remarkable reduction of disease severity whereas the lesions on the leaves of untreated plants developed apparently after the fungal inoculation. From these results, it was recomended that disease control using both bacterial isolates inducing systemic resistance in the field where chemical application is forbid.

• 한국자원식물학회:학술대회논문집
• /
• 한국자원식물학회 2010년도 정기총회 및 춘계학술발표회
• /
• pp.17-17
• /
• 2010

Ethylene, known as a stress hormone regulate wide developmental processes including germination, root hair initiation, root and shoot primordial formation and elongation, leaf and flower senescence and abscission, fruit ripening. The acceleration of ethylene biosynthesis in plant associated with environmental and biological stresses. 1-Aminocycloprophane-1-carboxlyate deaminase(ACCD) is an enzyme that cleaves ACC into and ammonia, a precursor of the plant hormone ethylene. Plant growth-promoting rhizobacteria (PGPR) having ACCD can decrease endogenous ACC level of tissue, resulting in reduced production of ethylene in plants. ACC deaminse was a key enzyme for protect stressed plants from injurious effects of ethylene. ACCD gene was encoded from Pseudomonas flourescens, PGPR and was cloned in Escherichia coli. We expressed the recombinant ACCD(rACCD) containing 357 amino acids with molecular weight 39 kDa that revealed by SDS-PAGE and western blot. The rACCD was purified by Ni-NTA purification system. The active form of rACCD having enzyme activity converted ACC to a-ketobutyrate. The optimal pH for ACC deaminase activity was pH 8.5, but no activity below pH 7.0 and a less severe tapering activity at base condition resulting in loss of activity at over pH 11. The optimal temperature of the enzyme was $30^{\circ}$ and a slightly less severe tapering activity at 15 - 30$^{\circ}$, but no activity over $35^{\circ}$. P. flourescens ACC deaminase has a highly conserved residue that plays in allowing substrate accessibility to the active sites. The enzymatic properties of this rACCD will provide an important reference for analysis of newly isolated ACCD and identification of newly isolated PGPR containing ACCD.

• 한국미생물·생명공학회지
• /
• 제34권1호
• /
• pp.78-82
• /
• 2006

Since there could be more and rather various diazotrophs in rhizosphere of wild crops than those in rhizosphere of cultivars, some wild gramineous crops grown in Korea were collected for isolating nitrogen-fixing bacteria. Six diazotrophs were purified from their roots using nitrogen-free media. The isolated bacteria were partially identified as 4 genera by 16S rDNA sequence analysis: Stenotrophomonas sp., Bosea sp., Klebsiella sp., and Azorhizobium sp. By PCR amplification and sequence analysis, DNA fragments extracted from all isolates turned out to have an individual nifH homologous gene. Five isolates (KNUC163, KNUC165, KNUC169, KNUC170, and KNUC171) showed auxin activity and four isolates (KNUC163, KNUC166, KNUC170, and KNUC171) produced siderophores. Especially,3 strains of S. maltophilia showed both auxin and siderophore activities. In conclusion, the isolated nitrogen-fixing bacteria might have capabilities for plant growth promotion.

• 한국미생물·생명공학회지
• /
• 제35권1호
• /
• pp.58-65
• /
• 2007

중금속으로 오염된 토양을 정화하기 위한 rhizoremediation 기법에서 식물이 중금속을 흡수하고 이동시키는 효율을 증가시키기 위하여 토양 미생물 특히, 근권세균의 역할이 중요하다. 이를 위하여 본 연구에서는 정유공장 주변의 유류 및 중금속으로 장기간 오염된 토양에서 서식하는 4가지 식물의 근권토양으로부터 Methylobacterium sp. SY-NiR1 균주를 분리하였다. 분리한 Methylobacterium sp. SY-NiR1는 분홍색 콜로니 형성, 막대모양 및 $\alpha-proteobacteria$에 속하는 특성으로 보아 pink-pigmented facultative methylotroph인 것으로 사료된다. 이 균주는 식물성호르몬인 indole acetic acid(IAA) 생산능을 가지고 있으며, 카드뮴, 크롬, 구리, 납, 니켈 그리고 아연 등과 같은 다양한 중금속에 대하여 내성을 가지고 있었으며, $EC_{50}$을 기준으로 한 SY-NiR1의 중금속에 대한 내성은 Zn > Ni > Cu > Pb > Cd > Cr 순이다. 따라서 본 연구에서 분리한 Methylobacterium sp. SY-NiR1 균주는 중금속으로 오염된 토양에서 식물의 발아, 생장 및 발달을 도와 식물의 중금속 흡수를 증가시켜 rhizorememdiation 효율을 증가시킬 수 있을 것으로 기대된다.

• 농약과학회지
• /
• 제13권4호
• /
• pp.275-282
• /
• 2009

선발된 PGPR 균주인 Bacillus subtilis C4와 Bacillus cereus D8 균주의 유채에 대한 생육촉진 및 무름병균인 Erwinia carotovora와 균핵병균인 Sclerotinia sclerotiorum에 대한 방제효과를 검정하기 위하여 실내검정과 온실검정을 실시하였다. 실내검정 결과, C4와 D8균주처리에 의하여 유채의 생육이 40.3%~74% 증가하였으며 무름병이 대조구에 비하여 80% 감소하였다. 실내검정에서 C4와 D8균주를 종자에 처리하였을 때 뿌리가 크게 신장되었다. 주요 식물병원균 Sclerotinia sclerotiorum, Rhizoctonia solani, Botrytis cinerea, Fusarium oxysporum, Phytophthora capsici, Colletotrichum acutatum에 대하여 항균활성시험을 수행한 결과 두 균주 중 C4균주는 모든 병원성 곰팡이에 대하여 항균활성을 나타내었다. 온실검정에서 C4와D8균주처리는 대조구에 비하여 유채의 초장, 엽폭 및 엽장을 19.5%~24.9%, 11.3%~15.3%, 14.1%~20.7% 각각 증가시켰으며 균핵병균인 Sclerotinia sclerotiorum에 대한 억제효과가 우수하였다. 이와 같은 결과를 볼 때 C4, D8 균주 처리는 유채의 생육을 촉진시키며 유채에 저항성을 유도하므로 친환경생물방제에 적용할 수 있을 것으로 생각된다.

• 한국식물병리학회지
• /
• 제14권1호
• /
• pp.13-18
• /
• 1998

The use of bioluminescence as a sensitive marker for the detection of Pseudomnas sp. in the rhizosphere was investigated. Transposon Tn4431 which contains a promoterless luciferase operon and tetracycline resistant gene was used. This transposon, present on a suicide vector (pUCD623) in E. coli HB101, was mated with spontaneous rifampicin mutant of Pseudomonas fluorescens B16, a plant growth promoting rhizobacteria (PGPR), and then rifampicin and tetracycline resistant survivors were isolated. Twenty tow mutants wer isolated from the conjugants between E. coli HB101 and P. fluorescens B16. One of these, B16::Tn4431 (L22) recombinant which glowed brightly in the dark was selected for analysis. The cucumber seeds inoculated with L22 were grown in moisten two layers of filter paper and nonsterile soil contained in half cut PVC pipe. The roots were removed from the filter paper and PVC pipe, then placed on the 1/2 LB media plates. The plates were incubated at room temperature for 16 hr. L22 could successfully be detected in the rhizoplane by using the ordinary negative camera film (ASA100-400) with 30 minutes exposure under dark condition. The root colonizing ability and the plant growth promoting effect of L22 were not reduced compared to the untreated bacteria and wild type. L22 was superior to will type.

• Applied Biological Chemistry
• /
• 제47권1호
• /
• pp.17-21
• /
• 2004

경작지 근권토양에서 식물생장촉진물질인 auxin라 항진균물질을 동시에 생산하는 농업용 미생물제제로 사용할 PGPR 균주를 선발하고 동정하였다. 경북 경산 일대의 다수확 밭토양의 근권토양에서 균주를 선발하고 그 중 auxin 생산성이 높은 2균주 K36, N21를 분리하였다. 이들 균주를 동정한 결과 K36은 Pantoea agglomerans이고 N21은 Pseudomonans fulva로 동정되었다. 선발된 균주의 식물생장촉진능을 in vivo 녹두발아촉진검사법으로 확인하였으며, 식물병원진균에 대한 길항력을 확인하였다. 배양조건에 따른 auxin 생산성을 조사한 결과 K36 균주는 $pH\;7.5,\;35^{\circ}C$, 37시간에서 최대로 나타났고, N21균주는 $pH\;7.5,\;35^{\circ}C$, 20시간에서 최대값을 나타내었다.

• The Plant Pathology Journal
• /
• 제31권2호
• /
• pp.195-201
• /
• 2015

Plant growth promoting rhizobacteria (PGPR) are known to confer disease resistance to plants. Bacillus sp. JS demonstrated antifungal activities against five fungal pathogens in in vitro assays. To verify whether the volatiles of Bacillus sp. JS confer disease resistance, tobacco leaves pre-treated with the volatiles were damaged by the fungal pathogen, Rhizoctonia solani and oomycete Phytophthora nicotianae. Pre-treated tobacco leaves had smaller lesion than the control plant leaves. In pathogenesis-related (PR) gene expression analysis, volatiles of Bacillus sp. JS caused the up-regulation of PR-2 encoding ${\beta}$-1,3-glucanase and acidic PR-3 encoding chitinase. Expression of acidic PR-4 encoding chitinase and acidic PR-9 encoding peroxidase increased gradually after exposure of the volatiles to Bacillus sp. JS. Basic PR-14 encoding lipid transfer protein was also increased. However, PR-1 genes, as markers of salicylic acid (SA) induced resistance, were not expressed. These results suggested that the volatiles of Bacillus sp. JS confer disease resistance against fungal and oomycete pathogens through PR genes expression.

• 한국유기농업학회지
• /
• 제26권3호
• /
• pp.463-475
• /
• 2018

국내 일부 시설재배지는 장기간 과도한 양분 투입 등에 의한 염류 집적 현상이 문제가 되어왔으며, 최근 이상기온에 따른 온도장해에 의한 피해도 발생하고 있다. 이러한 현상에 대해 친환경적으로 대처하기 위하여 고염류와 온도 스트레스에 대해 작물에 내성을 증강시키는 미생물을 선발하였다. 국내 토양에서 분리한 1,944균주중 고염류 또는 온도 스트레스 조건에서 세균의 생장과 식물생장촉진 관련 특성(IAA 생성, ACC deaminase 활성, 인산가용화능)을 고려하여 20균주를 1차 선발(전체 균주의 1.03%)하였다. 1차 선발한 20균주 중 토마토 식물검정을 통해 고염류 또는 온도스트레스에 대한 내성을 유도하는 7세균(1차 선발균주의 35%, 전체 균주의 0.36%)을 단계적으로 선발할 수 있었다. 선발된 세균은 16S rRNA 유전자의 염기서열 분석을 통해 모두 Bacillus 속에 속하는 것으로 확인되었다. 이러한 결과로 선발된 7균주는 토마토의 고염류 또는 온도 스트레스에 대한 효과적인 미생물 제제로 활용이 가능한 것을 확인할 수 있었다.

• Journal of Microbiology and Biotechnology
• /
• 제16권10호
• /
• pp.1650-1655
• /
• 2006

Bacteria belonging to the genus Paenibacillus are facultatively anaerobic endospore formers and are attracting growing ecological and agricultural interest, yet their genome information is very limited. The present study surveyed the genomic features of P. polymyxa ATCC $842^T$ using pulse-field gel electrophoresis of restriction fragments and sample genome sequencing of 1,747 reads (approximately 17.5% coverage of the genome). Putative functions were assigned to more than 60% of the sequences. Functional classification of the sequences showed a similar pattern to that of B. subtilis. Sequence analysis suggests nitrogen fixation and antibiotic production by P. polymyxa ATCC $842^T$, which may explain its plant growth-promoting effects.