• 한국토양비료학회지
• /
• 제49권3호
• /
• pp.251-258
• /
• 2016

A rhizobacterium LPN-2, which showed strong antifungal activity and auxin producing ability, was isolated from a farmland in North Gyeongsang Province, South Korea. Based on analysis of the 16S rDNA sequence, strain LPN-2 was identified as a novel strain of Burkholderia and was designated as Burkholderia sp. LPN-2. In vitro experiments showed that the isolated stain LPN-2 significantly produced auxin within 48 hr incubation. In order to check for PGPR function we performed in vivo growth promoting test in different crops, including mung bean, pea and cabbage. Application of Burkholderia sp. LPN-2 showed dramatic growth promoting effect on all the tested plants. We also confirmed siderophore and cellulase productions by Burkholderia sp. LPN-2 using CAS blue agar and CMC plate test. Further treatment with LPN-2 and the crude culture broth was effective in suppressing anthracnose in vitro test and also reduced incidence and severity of anthracnose in apple and pepper. Taken together, we conclude that Burkholderia sp. LPN-2 might be used as organic fertilizer for effective crop production in organic farming.

• 한국토양비료학회지
• /
• 제45권1호
• /
• pp.59-65
• /
• 2012

Plant growth-promoting effects of rhizobacterial inoculation obtained in pot experiments cannot always be dependably reproduced in fields. In this study, we investigated the effect of inoculation with Azospirillum brasilense and Methylobacterium oryzae, which have displayed growth promoting effects in several pot experiments, on growth and fruit yield of red pepper under field condition in a plastic-film house. Four rows spaced 90 cm apart were prepared after application of compost ($10Mg\;ha^{-1}$), and red pepper seedlings (Capsicum annum L., Nocgwang) were transplanted in each row with 40-cm space. Experimental treatments were consisted of A. brasilense CW903 inoculation, M. oryzae CBMB20 inoculation, and uninoculated control. Twelve plots, 10 plants per plot, were allotted to the three treatments with four replicates in a completely randomized design. At the time of transplanting, 50 mL of each inoculum ($1{\times}10^8cells\;mL^{-1}$) was introduced into root zone soil of each plant, and re-inoculated at 7 and 14 days after transplant. Plant growth and fruit yield were measured during the experiment. Both A. brasilense CW903 and M. oryzae CBMB20 could not promote growth of red pepper plants. All growth parameters measured were not significantly different among treatments. There were large variations in fruit yield recorded on plot basis, and no statistically significant differences were found among treatments. The failure to demonstrate the expected plant growth promoting effect of the inoculants is possibly due to various environmental factors, including weather and soil characteristics, reducing the possibility to express the potential of the inoculated bacterial strains.

• 미생물학회지
• /
• 제46권1호
• /
• pp.33-37
• /
• 2010

근권토양에서 분리한 세균 Bacillus subtilis RFO41은 인산 가용화능이 높고 auxin 등의 식물호르몬을 생산한다. 이 균주를 이용하여 가시도꼬마리(Xanthium italicum Moore)의 생장 촉진 실험을 화천군 파로호의 호안나대지에서 수행하였다. 19주 경과 후 자라난 가시도꼬마리를 채취하여 줄기와 뿌리 길이를 측정하고 식물을 건조시켜 중량을 측정하였다. 균주를 처리한 접종군이 미접종 대조군보다 가시도꼬마리의 건조중량이 67.7%나 높았으며 또한 가시도꼬마리의 줄기 길이도 균주를 처리한 접종군이 미접종 대조군보다 21.1% 길었는데 모두 통계적 유의성을 가졌다. 접종균주의 동태를 denaturing gradient gel electrophoresis 방법으로 조사하였는데 나대지 토양에서 접종균주가 유지되고 있으며 토양의 고유 세균군집에는 큰 영향을 미치지 않는 것을 확인하였다. 따라서 척박한 호안나대지 토양에서 B. subtilis RFO41의 인산가용화능과 식물호르몬의 생성능 등의 식물생장촉진 효과가 가시도꼬마리의 생장에 직접적인 영향을 미치는 것으로 판단할 수 있다. 이러한 식물 생장 촉진효과는 친환경적 미생물비료, 특히 민감한 호안나대지 등의 미생물학적 식생복원방법으로서의 가치를 뒷받침하는 것이라 할 수 있다.

• Mycobiology
• /
• 제40권4호
• /
• pp.244-251
• /
• 2012

In vitro and greenhouse screening of seven rhizobacterial isolates, AB05, AB10, AB11, AB12, AB14, AB15 and AB17, was conducted to investigate the plant growth promoting activities and inhibition against anthracnose caused by Colletotrichum acutatum in pepper. According to identification based on 16S rDNA sequencing, the majority of the isolates are members of Bacillus and a single isolate belongs to the genus Paenibacillus. All seven bacterial isolates were capable of inhibiting C. acutatum to various degrees. The results primarily showed that antibiotic substances produced by the selected bacteria were effective and resulted in strong antifungal activity against the fungi. However, isolate AB15 was the most effective bacterial strain, with the potential to suppress more than 50% mycelial growth of C. acutatum in vitro. Moreover, antibiotics from Paenibacillus polymyxa (AB15) and volatile compounds from Bacillus subtilis (AB14) exerted efficient antagonistic activity against the pathogens in a dual culture assay. In vivo suppression activity of selected bacteria was also analyzed in a greenhouse with the reference to their prominent in vitro antagonism efficacy. Induced systemic resistance in pepper against C. acutatum was also observed under greenhouse conditions. Where, isolate AB15 was found to be the most effective bacterial strain at suppressing pepper anthracnose under greenhouse conditions. Moreover, four isolates, AB10, AB12, AB15, and AB17, were identified as the most effective growth promoting bacteria under greenhouse conditions, with AB17 inducing the greatest enhancement of pepper growth.

• The Plant Pathology Journal
• /
• 제24권1호
• /
• pp.67-73
• /
• 2008

Seedling damping-off and bottom rot caused by Rhizoctonia solani are yield limiting diseases of crisphead lettuce. To provide biocontrol measure in the management of the diseases, biocontrol strain Pseudomonas aeruginosa LY-11 was isolated from lettuce rhizosphere and introduced into crisphead lettuce rhizosphere by the seed coating delivery method. Alginate was used as a coating material to generate beads containing $10^6-10^{6.5}$ colony-forming units (CFUs) of viable bacterial cells of LY-11. When seeds germinated from the alginate beads containing the strain LY-11, the bacteria established mostly in plant rhizosphere to maintain at least $10^4$ CFU per gram of plant tissues. Crisphead lettuce seedlings germinated from the entrapped seeds were less affected from damping-off and bottom rot with disease control values of 70.4% and 85.4% respectively. Although P. aeruginosa LY-11 colonized plant rhizosphere and not phyllosphere, the result indicated that bottom rot caused by the foliar inoculation of R. solani was effectively reduced by the rhizobacteria. All data suggested that immobilized rhizobacterial application in seeds by alginate coating could control damping-off and induce induced systemic resistance of crisphead lettuce to reduce bottom rot.

• 미생물학회지
• /
• 제48권4호
• /
• pp.246-253
• /
• 2012

연령을 달리하는 인삼토양 내 근권세균의 다양성과 이들 세균이 갖고 있는 식물생장에 유용한 특성에 대하여 조사하였다. 인삼 근권으로부터 총 15개 속에 포함되는 143 균주를 분리하였다. 인삼 연령에 따른 세균 군집의 변화가 있었으나, 분리 균주의 58%가 Firmicutes에 속하였다. 특히 Bacillus는 연령에 관계없이 가장 우점하는 속으로 나타났다. 이들 분리 균주 중 30개의 균주를 선발하여 세포벽 분해효소 분비, 인돌아세트산 생성, siderophore 생성, 인 가용화, 식물병원성 곰팡이의 저해능 등에 대하여 평가한 결과, 다수의 균주가 식물생장을 촉진할 수 있는 기능적 특성을 갖고 있었다. 이 중에서도 모든 조사 항목에 대하여 양성 반응을 보인 B. subtilis, B. amyloliquefaciens, B. velezensis, B. licheniformis 균주는 향후 인삼 경작을 위한 생장 촉진 미생물제제로 활용가치가 높을 것으로 기대된다.

• 환경생물
• /
• 제25권4호
• /
• pp.356-362
• /
• 2007

충남 태안군 일대 4곳의 해안사구 지역에서 자생하는 9종의 사구식물 연관 근권세균 다양성을 2003년 10월부터 2004년 3월까지의 기간 동안 3차례에 걸쳐 denaturing gradient gel electrophoresis (DGGE) 기법을 이용하여 조사하였다. 그 결과 한 밴드가 계속 모든 시료에서 우점하는 것으로 나타났으며, DNA 염기서열 분석에 의하여 Lysobacter enzymogenes와 가장 유사한 것으로 나타났다. 기타 주요 밴드들은 Pseudomonas와 Bacillus 속의 균주들로 동정되었다. L. enzymogenes가 9종의 식물 모두에서 지역이나 조사시기에 관계없이 우점적으로 나타난 것은 이전의 클론 분석을 통한 결과와 일치한다 (Lee et al. 2006a). Bacillus에 속한 밴드들이 모든 조사에서 출현하였으며, Pseudomonas 속 밴드들은 2003년 12월 조사에서 두드러졌다. DGGE 분석만으로는 Lysobacter가 사구식물에 가지는 중요성을 파악할 수는 없으나 건강한 개체에 지속적으로 발견되는 것으로 보아 Lysobacter의 존재는 식물에 긍정적인 영향을 가지는 것으로 사료된다.

• The Plant Pathology Journal
• /
• 제23권1호
• /
• pp.22-25
• /
• 2007

Biocontrol activity of five strains of selected rhizo-bacteria were tested in tomato against bacterial wilt caused by Ralstonia solanacearum. After root bacterization the plants were grown in a perlite-hydroponic system. Upon challenge inoculation with the pathogen, all of the rhizobacterial strains efficiently suppressed the bacterial wilt in tomato in various rates, at maximum by the strain, Bacillus vallismortis strain EXTN-1. While the percent of infected plants in the non-bacterized control plants were 95%, it was only 65% in plants pre-treated with EXTN-1. It was also demonstrated that the movement of R. solanacearum within the stem was significantly hampered when the plants were root bacterized. As EXTN-1 has no antagonistic properties against R. solanacearum, the bacterial wilt was probably suppressed by a mechanism other than antibiosis. Previously, the strain had been proven to produce an efficient elicitor for inducing systemic resistance in many crops. As the present study confirmed that EXTN-1 has the ability for reducing the pathogen spread in tomato, the strain could be effectively used as a potential biocontrol agent against bacterial wilt.

• 식물병연구
• /
• 제14권1호
• /
• pp.32-36
• /
• 2008

Ralstonia solanacearum에 의한 풋마름병은 토마토, 감자 등의 작물에 심각한 피해를 주고 있으나, 효과적인 방제법이 없는 실정이다. 일반 병원균의 생물적 방제를 위해 Pseudomonas속의 세균이 가장 일반적으로 이용되고 있는데, 이번 연구에서는 각종 작물의 재배지 토양에서 형광성 세균을 분리하여 Pseudomonas속 특이적 PCR과 항생물질(2,4-diacetylphloroglucinol) 생산 관련 유전자의 유무를 조사하였다. 분리된 150개의 Pseudomonas속 세균 중 항생물질 관련 유전자가 검출된 균은 2균주뿐이였으며, 그중 토마토 근권토양으로 분리된 P. putida P84 세균이 각종 식물 병원 세균에 대해 가장 높은 실내 항균력을 나타내었다. P84 균주의 탄소원별 증식효과는 glucose 첨가시에 가장 좋았으며, arabionse, inositol, melibiose 첨가시에도 우수한 증식효과를 나타내었다. P84세균을 이용한 토마토 풋마름병의 포트실험 결과에서는 60%의 방제효과를 나타내었다.

• Mycobiology
• /
• 제35권3호
• /
• pp.129-134
• /
• 2007

Systemic effect of two plant growth-promoting rhizobacterial (PGPR) strains, viz., Pseudomonas fluorescens (Pf4) and P. aeruginosa (Pag), was evaluated on pea (Pisum sativum) against the powdery mildew pathogen Erysiphe pisi. Foliar spray of the two PGPR strains was done on specific nodal leaves of pea and conidial germination of E. pisi was observed on other nodal leaves, distal to the treated ones. Conidial germination was reduced on distant leaves and at the same time, specific as well as total phenolic compounds increased in the leaves distal to those applied with PGPR strains, thereby indicating a positive correlation. The strains induced accumulation of phenolic compounds in pea leaves and the amount increased when such leaves were get inoculated with E. pisi conidia. Between the two strains, Pag was found to be more effective than Pf4 as its effect was more persistent in pea leaves. Foliar application of PGPR strains for the control of powdery mildew of pea is demonstrated in vitro while correlating it with the increased accumulation of plant phenolics.