• 생명과학회지
• /
• 제31권7호
• /
• pp.641-653
• /
• 2021

본 연구에서는 근권토양으로부터 18종의 세균을 순수분리하고, 이들의 식물 병원성 진균 생육억제 활성, 식물생장촉진 활성 및 미네랄 가용화능을 평가하였다. Bacillus 속과 Pseudomonas 속 분리균주의 항진균 활성을 통해 생물학적 방제제로서의 가능성을 확인할 수 있었으며, 이는 식물 병원성 진균의 세포벽에 작용하는 여러 가수분해효소 활성과 siderophore 생성능 등에 기인된 것으로 판단된다. 또한 대부분의 분리균주가 aminocyclopropane-1-carboxylate deaminase 생성능, indole-3-acetic acid 생성능 및 질소 고정능을 갖고 있는 것으로 나타났으며, 이러한 특성은 식물이 흔히 노출될 수 있는 환경 스트레스 조건 하에서 스트레스 에틸렌의 농도를 감소시킴으로써 뿌리 발달 및 성장, 그리고 작물의 생산성에 긍정적인 영향을 줄 것으로 판단된다. 그리고 분리균주의 인산, 규소, 탄산칼슘, 아연 가용화능 등을 확인한 결과, 일부 분리균주들의 미네랄 가용화능을 확인하였으며, 이들 분리균주를 식물 생장 시에 접종한다면 식물 생장에 필요한 영양분을 식물이 흡수할 수 있는 이용가능한 형태로 변환시켜 식물의 생장에 도움을 줄 수 있을 것으로 기대된다. 이러한 항진균 활성, 식물생장촉진 활성 및 미네랄 가용화능의 결과를 통해 분리균주 18종의 biocontrol agent로서의 이용가능성을 제시하고자 한다.

• 한국미생물·생명공학회지
• /
• 제49권3호
• /
• pp.374-383
• /
• 2021

Rhizoctonia solani is one of the major pathogens that cause sheath blight disease in rice. Sheath blight is one of the most difficult diseases to control. Biological control (with the use of rhizobacteria) is one of the ways to control this disease. Plant Growth Promoting Rhizobacteria (PGPR) is a rhizosphere bacterium that can be used to enhance plant growth. The composition of the rhizobacteria in organic and nonorganic soil is affected by the chemical characteristics of the soil - which influences plant physiology and root exudation patterns. This study aimed to obtain a species of rhizobacteria which shows PGPR activity, from organic and nonorganic rice fields and test their capability to suppress R. solani growth. Out of 23 isolates screened for PGPR activity, the following isolates showed high PGPR activity and were selected for in vitro antagonistic activity testing against R. solani: ISO6, ISO11, ISO15, ISN2, ISN3, and ISN7, The six isolates produced 43,42-75,23 ppm of IAA, possessed phosphorus solubilization capability, and chitinase-producing activity. ISO6 (54.88%) and ISN7 (83.33%) displayed high inhibition capacities against R. solani, in vitro. ISO6 and ISN7 inhibited the growth of R. solani lesions on rice leaves by 89% and 100% (without lesion), respectively, after 7 days of incubation. Analysis of their 16S rRNA sequences revealed that the ISO6 isolate was Citrobacter freundii and ISN7 isolate was Pseudomonas aeruginosa.

• Journal of Microbiology and Biotechnology
• /
• 제7권1호
• /
• pp.13-20
• /
• 1997

Plant growth-promoting Psudomonas fluorescens GL20 was isolated from a ginseng rhizosphere on chrome azurol Sagar. P. fluorescens GL20 produced a large amount of hydoxamate siderophore in an iron-deficient medium. The siderophore showed significantly high specific activity of 20.2 unit. Using an in vitro antifungal test, P. fluorescens GL20 considerably suppressed growth of phytopathogenic fungus Fusarium solani, inhibiting spore germination and germ tube elongation. In pot trials of kidney beans with P. fluorescens GL20, disease incidence was remarkably reduced up to $68{\%}$ compared with that of F. solani alone, and plant growth was also increased nearly 1.6 fold as compared to that of the untreated control, promoting elongation and development of the roots. These results indicate that the plant growth-promoting activity of P. fluorescens GL20 can play an important role in biological control of soil-borne plant disease in a rhizosphere, enhancing the growth of plants.

• Mycobiology
• /
• 제42권2호
• /
• pp.158-166
• /
• 2014

In this study, bacterial strains were isolated from soils from 30 locations of Samcheok, Gangwon province. Of the isolated strains, seven showed potential plant growth promoting and antagonistic activities. Based on cultural and morphological characterization, and 16S rRNA gene sequencing, these strains were identified as Paenibacillus species. All seven strains produced ammonia, cellulase, hydrocyanic acid, indole-3-acetic acid, protease, phosphatase, and siderophores. They also inhibited the mycelial growth of Fusarium oxysporum f. sp. radicis-lycopersici in vitro. The seven Paenibacillus strains enhanced a range of growth parameters in tomato plants under greenhouse conditions, in comparison with non-inoculated control plants. Notably, treatment of tomato plants with one identified strain, P. polymyxa SC09-21, resulted in 80.0% suppression of fusarium crown and root rot under greenhouse conditions. The plant growth promoting and antifungal activity of P. polymyxa SC09-21 identified in this study highlight its potential suitability as a bioinoculant.

• Journal of Microbiology and Biotechnology
• /
• 제31권9호
• /
• pp.1218-1230
• /
• 2021

Cold-adapted plant growth-promoting bacteria (PGPB) with multiple functions are an important resource for microbial fertilizers with low-temperature application. In this study, culturable cold-adapted PGPB strains with nitrogen fixation and phosphorus solubilization abilities were isolated. They were screened from root and rhizosphere of four dominant grass species in nondegraded alpine grasslands of the Qilian Mountains, China. Their other growth-promoting characteristics, including secretion of indole-3-acetic acid (IAA), production of siderophores and ACC deaminase, and antifungal activity, were further studied by qualitative and quantitative methods. In addition, whether the PGPB strains could still exert plant growth-promoting activity at 4℃ was verified. The results showed that 67 isolates could maintain one or more growth-promoting traits at 4℃, and these isolates were defined as cold-adapted PGPB. They were divided into 8 genera by 16S rRNA gene sequencing and phylogenetic analysis, of which Pseudomonas (64.2%) and Serratia (13.4%) were the common dominant genera, and a few specific genera varied among the plant species. A test-tube culture showed that inoculation of Elymus nutans seedlings with cold-adapted PGPB possessing different functional characteristics had a significant growth-promoting effect under controlled low-temperature conditions, including the development of the roots and aboveground parts. Pearson correlation analysis revealed that different growth-promoting characteristics made different contributions to the development of the roots and aboveground parts. These cold-adapted PGPB can be used as excellent strain resources suitable for the near-natural restoration of degraded alpine grasslands or agriculture stock production in cold areas.

• Journal of Applied Biological Chemistry
• /
• 제43권2호
• /
• pp.104-108
• /
• 2000

The plant growth-promoting activity of Acremonium strictum MJN1 isolated from roots of Panox ginseng was explored. The myceliaI extract of A. strictum MJN1 enhanced the rice seedling growth by 14.5 and 9.0% in the dried weight of shoots and roots, and the growth of red pepper by 54 and 85% in the top length and the dried weight in pot experiments, respectively. The plant growth-promoting substances in the myceliaI extract of Acremonium strictum MJN1 were identified as D-adenosine and glycerol. Both commercial D-adenosine and glycerol also promoted significantly the rice seedling growth but, unlike the mycelial extract of A. strictum MJN1, hardly affected the yields of plants grown in pots or field. Therefore, it is possible that other plant growth-promoting substances are produced by A. strictum MJN1. However, this study shows that A. strictum MJN1 has a great potential as a biofertilizer.

• Journal of Microbiology and Biotechnology
• /
• 제17권8호
• /
• pp.1300-1307
• /
• 2007

This study assessed the possible role of different traits in selected plant growth-promoting rhizobacteria (PGPR) for improving wheat growth and yield under natural conditions. Rhizobacteria exhibiting 1-aminocyclopropane-1-carboxylate (ACC)-deaminase activity were isolated and screened for their growth-promoting activity in wheat under axenic conditions. Five isolates belonging to Pseudomonas and one Burkholderia caryophylli isolate that showed promising performances under axenic conditions were selected and characterized for in vitro ACC-deaminase activity, chitinase activity, auxin production, P solubilization, and root colonization. These isolates were then used as inocula for wheat cultivated under natural conditions in pot and/or field trials. Significant increases in root elongation, root weight, tillers per pot, 1,000-grain weight, and grain and straw yields were observed in response to inoculation with PGPR in the pot trials. Inoculation with these PGPR was also effective under field conditions and increased the wheat growth and yield significantly. However, the efficacy of the strains was inconsistent under the axenic, pot, and field conditions. Pseudomonas fluorescens ($ACC_{50}$), which exhibited a relatively high in vitro ACC-deaminase activity, chitinase activity, auxin production, and P solubilization and more intensive root colonization, was the most efficient isolate under the field conditions. Therefore, these results demonstrated that ACC-deaminase activity is an efficient parameter for the selection of promising PGPR under axenic conditions. However, additional traits of PGPR, including auxin production, chitinase activity, P solubilization, and root colonization, are also important for selecting PGPR as biofertilizers.

• 식물병연구
• /
• 제12권1호
• /
• pp.46-50
• /
• 2006

비경작 산림 토양으로부터 고추역병 억제와 초기생육 촉진 효과를 보이는 방선균을 분리하였다. 분리된 Streptomyces griseofuscus 200401은 역병균 뿐만 아니라 탄저병에 대하여 항균활성을 보였다. 분리 미생물 배양액과 그 제제의 생육초기단계 처리로 식물체의 엽수, 생물 중 및 건물 중 등이 대조구에 비해 증가하였다. 공시균주 배양액 중 유기질소원의 분해에 의한 ammonium chloride의 농도는 배양 후 0.13 ${\mu}g/ml$로 나타났다. 분리균주의 온실에서 고추역병 발생억제 효과를 검정한 결과, 1주일 간격으로 3회 처리한 경우 최종방제가가 37.3%로 대조약제와 유사하게 나타났다.

• Journal of Microbiology and Biotechnology
• /
• 제28권6호
• /
• pp.968-975
• /
• 2018

In the course of screening for microbes with nematicidal activity, we found that Enterobacter asburiae HK169 displayed promising nematicidal activity against the root-knot nematode Meloidogyne incognita, along with plant growth-promoting properties. Soil drenching of a culture of HK169 reduced gall formation by 66% while also increasing root and shoot weights by 251% and 160%, respectively, compared with an untreated control. The cell-free culture filtrate of the HK169 culture killed all juveniles of M. incognita within 48 h. In addition, the nematicidal activity of the culture filtrate was dramatically reduced by a protease inhibitor, suggesting that proteolytic enzymes contribute to the nematicidal activity of HK169. In order to obtain genomic information about the HK169 isolate related to its nematicidal and plant growth-promoting activities, we sequenced and analyzed the whole genome of the HK169 isolate, and the resulting information provided evidence that the HK169 isolate has nematicidal and plant growth-promoting activities. Taken together, these observations enable the future application of E. asburiae HK169 as a biocontrol agent for nematode control and promote our understanding of the beneficial interactions between E. asburiae HK169 and plants.

• KSBB Journal
• /
• 제31권1호
• /
• pp.58-65
• /
• 2016

In this study, Arthrobacter scleromae SYE-3, which was isolated from indigenous plant in a subtropical region, Neigeria, with plant growth promoting activity was evaluated to determine the optimal culture condition. A bacterial strain SYE-3 had the IAA productivity ($89.15{\pm}0.36mg/L$) and ACC deaminase activity ($0.20{\pm}0.06$ at 72 hours). Also, optimal culture conditions such as temperature and pH of strain SYE-3 were $20^{\circ}C$ and 10 in LB medium, respectively. Strain SYE-3 had up to 3% salt tolerance in the LB medium. Plant growth promoting ability of strain SYE-3 using yam (Dioscorea japonica Thunb.) was evaluated. As a result, strain SYE-3 had showed very powerful effect on the increase of the shoot length and root biomass of yam (190.0% and 282.41% increase for 112 days, respectively). These results indicated that Arthrobacter scleromae SYE-3 can serve as a promising microbial resource for the biofertilizers of subtropical crops.