• Mycobiology
• /
• 제46권1호
• /
• pp.13-23
• /
• 2018

Depending on the mode of nutrition exploitation, major fungal guilds are distinguished as ectomycorrhizal and saprotrophic fungi. It is generally known that diverse environmental factors influence fungal communities; however, it is unclear how fungal communities respond differently to environment factors depend on fungal guilds. In this study, we investigated basidiomycetes communities associated with Quercus mongolica using 454 pyrosequencing. We attempted to detect guild pattern (ectomycorrhizal or saprotrophic fungal communities) by comparing the influence of geography and source (root and surrounding soil). A total of 515 mOTUs were detected from root (321) and soil (394) of Q. mongolica at three sites of Mt. Jeombong in Inje County. We found that patterns of diversity and community structure were different depending on the guilds. In terms of alpha diversity, only ectomycorrhizal fungi showed significant differences between sources. In terms of community structure, however, geography significantly influenced the ectomycorrhizal community, while source appeared to have a greater influence on the saprotrophic community. Therefore, a guildbased view will help to elucidates novel features of the relationship between environmental factors and fungal communities.

• Journal of Microbiology and Biotechnology
• /
• 제31권10호
• /
• pp.1373-1382
• /
• 2021

Plant growth promoting rhizobacteria (PGPR) are a group of bacteria that can increase plant growth; but due to unfavorable environmental conditions, PGPR are biologically unstable and their survival rates in soil are limited. Therefore, the suitable application of PGPR as a plant growth stimulation is one of the significant challenges in agriculture. This study presents an intelligent formulation based on Bacillus velezensis VRU1 encapsulation enriched with nanoparticles that was able to control Rhizoctonia solani on the bean. The spherical structure of the capsule was observed based on the Scanning Electron Microscope image. Results indicated that with increasing gelatin concentration, the swelling ratio and moisture content were increased; and since the highest encapsulation efficiency and bacterial release were observed at a gelatin concentration of 1.5%, this concentration was considered in mixture with alginate for encapsulation. The application of this formulation which is based on encapsulation and nanotechnology appears to be a promising technique to deliver PGPR in soil and is more effective for plants.

• Journal of Species Research
• /
• 제10권3호
• /
• pp.201-216
• /
• 2021

During an investigation of indigenous prokaryotic species in the Republic of Korea, a total of 38 bacterial strains belonging to the class Gammaproteobacteria were isolated from diverse environments. Samples were collected from soil, seawater, sand, sedimentary soil, rabbit feces, rat intestines, marine wetland, and tidal flats. The strains were identified to the species level using the high 16S rRNA gene sequences and showed high similarity (>98.7%) with the closest bacterial species and formed a robust clade in the neighbor-joining phylogenetic tree; it was determined that each strain belonged to independent, predefined bacteria species within the class Gammaproteobacteria. The 38 strains of Gammaproteobacteria analyzed in this study have not been reported in the Republic of Korea. Therefore, this study describes 20 genera of 13 families in 8 orders: Aeromonadales, Alteromonadales, Cellvibrionales, Enterobacterales, Lysobacterales, Oceanospirillales, Pseudomonadales, and Vibrionales. For each species, we describe Gram reaction, strain ID, isolation source, colony and cell morphology, cultural, physiological, and basic biochemical characteristics.

• Mycobiology
• /
• 제49권6호
• /
• pp.534-550
• /
• 2021

During a survey of fungal diversity associated with insects, mud, soil, and freshwater niches in different areas in Korea, nine interesting fungal strains were isolated. Based on their morphological characteristics and molecular phylogeny analyses, using a combined data set of b-tubulin (BenA), calmodulin (CaM), and second largest subunit of RNA polymerase (RPB2) sequences, the strains CNUFC AM-44, CNUFC JCW3-4, CNUFC S708, CNUFC WT202, CNUFC AS1-29, CNUFC JCW3-5, CNUFC JDP37, and CNUFC JDP62 were identified as Aspergillus alabamensis, A. floridensis, A. subversicolor, Penicillium flavigenum, P. laevigatum, P. lenticrescens, Talaromyces adpressus, and T. beijingensis, respectively. The strain CNUFC JT1301 belongs to series Westlingiorum in section Citrina and is phylogenetically related to P. manginii. However, slow growth when cultivated on CYA, MEA, CREA is observed and the property can be used to easily distinguish the new species from these species. Additionally, P. manginii is known to produce sclerotia, while CNUFC JT1301 strain does not. Herein, the new fungal species is proposed as P. aquadulcis sp. nov. Eight species, A. alabamensis, A. floridensis, A. subversicolor, P. flavigenum, P. laevigatum, P. lenticrescens, T. adpressus, and T. beijingensis, have not been previously reported in Korea. The present study expands the known distribution of fungal species belonging to the families Aspergillaceae and Trichocomaceae in Korea.

• The Plant Pathology Journal
• /
• 제36권3호
• /
• pp.244-254
• /
• 2020

Gom-chwi (Ligularia fischeri) is severely infected with Phytophthora drechsleri, the causal organism of Phytophthora root rot, an economically important crop disease that needs management throughout the cultivation period. In the present study, Phytophthora root rot was controlled by using bacterial isolates from rhizosphere soils collected from various plants and screened for antagonistic activity against P. drechsleri. A total of 172 bacterial strains were isolated, of which, 49 strains showed antagonistic activities by dual culture assay. In the seedling assay, six out of the 49 strains showed a predominant effect on suppressing P. drechsleri. Among the six strains, the ObRS-5 strain showed remarkable against P. drechsleri when treated with seed dipping or soil drenching. The ObRS-5 strain was identified as Enterobacter asburiae based on 16S ribosomal RNA gene sequences analysis. The bacterial cells of E. asburiae ObRS-5 significantly suppressed sporangium formation and zoospore germination in P. drechsleri by 87.4% and 66.7%, respectively. In addition, culture filtrate of E. asburiae ObRS-5 also significantly inhibited sporangium formation and zoospore germination by 97.0% and 67.6%, respectively. Soil drenched bacterial cells, filtrate, and culture solution of E. asburiae ObRS-5 effectively suppressed Phytophthora root rot by 63.2%, 57.9%, and 81.1%, respectively. Thus, E. asburiae ObRS-5 could be used as a potential agent for the biological control of Phytophthora root rot infecting gom-chwi.

• Journal of Ecology and Environment
• /
• 제33권2호
• /
• pp.133-139
• /
• 2010

Atmospheric $CO_2$ concentrations have increased exponentially over the last century and, if continued, are expected to have significant effects on plants and soil. In this study, we investigated the effects of elevated $CO_2$ on the growth of Pinus densiflora seedling and microbial activity in soil. Three-year-old pine seedlings were exposed to ambient as well as elevated levels of $CO_2$ (380 and 760 ppmv, respectively). Growth rates and C:N ratios of the pine seedlings were also determined. Dissolved organic carbon content, phenolic compound content, and microbial activity were measured in bulk soil and rhizosphere soil. The results show that elevated $CO_2$ significantly increased the root dry weight of pine seedling. In addition, overall N content decreased, which increased the C:N ratio in pine needles. Elevated $CO_2$ decreased soil moisture, nitrate concentration, and the concentration of soil phenolic compounds. In contrast, soil enzymatic activities were increased in rhizosphere soil, including ${\beta}$-glucosidase, N-acetylglucosaminidase and phosphatase enzyme activities. In conclusion, elevated $CO_2$ concentrations caused distinct changes in soil chemistry and microbiology.

• 미생물학회지
• /
• 제35권1호
• /
• pp.65-71
• /
• 1999

BIOLOG GN microplate를 이용하여 6종의 식생 토양에 따른 토양미생물 군집의 유일탄소원 이용능을 비교 분석하였다. 전체적으로 축합물, 아미노산, 카르복실산 화합물을 잘 이용하였으나, amide의 경우 낮은 이용능을 보였다. 대응분석을 통해 6종류의 식생 토양에 따른 토양미생물 군집은 크게 삼림토양, 초지-경작지토양, 비식생 토양의 3가지 그룹의 대사적 다양성의 차이를 보이는 집단으로 분류되었다. 다차원 척도법 분석을 통해 신갈나무 삼림토양의 미생물 군집은 소나무와 떡갈나무 삼림토양의 미생물 군집과는 또 다른 그룹으로 분리되었다. 이러한 식생토양형에 다른 미생물 군집의 대사 다양성의 차이로 볼 때, 식생의천이에 따라 식생에 영향을 받는 미생물 군집의 대사 다양성 또한 식생의 천이에 대응하여 변화하고 있음을 확인하였다.

• 한국미생물·생명공학회지
• /
• 제25권6호
• /
• pp.537-545
• /
• 1997

The aim of the present research program was to isolate a strain of actinomycetes producing antifungal substance. Soil samples were collected from various sites in Korea and a number of actinomycetes were isolated from the soil samples by applying selective agar for actinomycetes. Among isolates, a strain (NA -52) producing antifungal substance against Pyricularia oryzae was selected. Chemotaxonomic and numerical identification were carried out for the isolate. Fifty taxonomic unit characters were tested and the data were analyzed numerically using TAXON program. The isolate was identified as a synonym of streptomyces diastaticus belong to cluster No. 19 (Streptomyces diastaticus). But it showed a low similarity to S. diastaticus in simple matching coefficients, hence it was considered as one new species in Streptomyces.

• Journal of Microbiology and Biotechnology
• /
• 제17권6호
• /
• pp.919-927
• /
• 2007

Antagonistic fluorescent pseudomonads isolated from rhizospheric soil of rice were characterized by 16S rRNA amplicon and fatty acid methyl ester (FAME) analyses. Antagonistic isolates were grown in the fermentation media, and production of antibiotics was confirmed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Production of fungal cell-wall-degrading enzymes such as protease, cellulase, pectinase, and chitinase was determined. Dendrogram based on the major and differentiating fatty acids resulted into 5 clusters, viz., cluster I (P. pseudoalcaligenes group), cluster II (P. plecoglossicida group), cluster III (P. fluorescens group), cluster IV (P. aeruginosa group), and cluster V (P. putida group). Characteristic presence of high relative proportions of cyclopropane (17:0 CYCLO w7c) was observed in antagonistic bacteria. Data revealed biodiversity among antagonistic fluorescent pseudomonads associated with the rice rhizosphere. Results presented in this study will help to identify the antagonistic isolates and to determine their mechanisms that mediate antagonism against fungal pathogens of rice.

• 한국미생물·생명공학회지
• /
• 제21권6호
• /
• pp.600-608
• /
• 1993

About 1, 300 strains isolated from soil were evaluated for acyl-CoA:cholesterol acyltransferase (ACAT) inhibition activity. About 4.0% of actinomycetes and 3.6% of fungi showed greater than 50% inhibition activity, respectively. However, none of the isolated bacteria exhibited inhibition activity more than 50%. Among them, one Streptomyces sp. A-3 showed a higher ACAT inhibition activity in culture broth. Isolation of the ACAT inhibitor (AI-3) was achieved by Amberlite XAD-7 column, silica-gel column, Sephadex LH-20 gel-filtration and reverse phase HPLC.