• Korean Journal of Microbiology
• /
• v.54 no.4
• /
• pp.471-473
• /
• 2018

Variovorax sp. PMC12 is a rhizobacterium isolated from tomato rhizosphere and enhanced the plant resistance to abiotic and biotic stresses. Here we present the complete genome sequence of strain PMC12. The genome is comprised of two circular chromosomes harboring 5,873,297 bp and 1,141,940 bp, respectively. A total of 6,436 protein-coding genes, 9 rRNAs, 64 tRNAs, 3 ncRNAs, and 80 pseudogenes were identified. We found genes involved in 1-aminocyclopropane-1-carboxylate (ACC) deaminase, antioxidant activity, phosphate solubilization, and biosynthesis of proline and siderophore. Those genes may be related to capability of improving plant resistance to various stresses including salinity, cold temperature, and phytopathogen.

• Korean Journal of Microbiology
• /
• v.52 no.2
• /
• pp.148-156
• /
• 2016

This study examined effects of Enterobacter ludwigii SJR3 showing a high 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, on growth of tomato plant and its expression of stress-related genes under drought and salt stress. SJR3 strain was inoculated at $10^6cell/g$ soil to 4-week grown tomato plants, and drought and salt stresses were treated. After additional incubation for 1 week, root length, stem length, fresh weight and dry weight of tomato plants treated with SJR3 increased by 37.8, 37.2, 96.8 and 146.6%, respectively compared to those of uninoculated plants in drought stress environment, and they increased by 19.2, 25.4, 19.5, and 105.8%, respectively in salt stress environment. Proline content in tomato leaves increased significantly under stress conditions as one of a protecting substance against stresses, but proline contents in tomato treated with SJR3 decreased by 62.1 and 54.1%, respectively. Relative expression of genes encoding ACC oxidase, ACO1 and ACO4, ethylene response factor genes ERF1 and ERF4, and some other stress-related genes were examined from tomato leaves. Compared to the non-stressed tomato, expressions of all stress-related genes increased significantly in the stressed tomato, but gene expressions in the inoculated tomato were similar to those of no-stressed control tomato. Therefore, E. ludwigii SJR3 may play an important role in mitigating drought and salt stress in plants, and can increase productivity of crops under various abiotic stresses.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.12
• /
• pp.1724-1734
• /
• 2010

A phosphate-solubilizing bacterial strain isolated from Hippophae rhamnoides rhizosphere was identified as Rahnella sp. based on its phenotypic features and 16S rRNA gene sequence. The bacterial strain showed the growth characteristics of a cold-adapted psychrotroph, with the multiple plant growth-promoting traits of inorganic and organic phosphate solubilization, 1-aminocyclopropane-1-carboxylate-deaminase activity, ammonia generation, and siderophore production. The strain also produced indole-3-acetic acid, indole-3-acetaldehyde, indole-3-acetamide, indole-3-acetonitrile, indole-3-lactic acid, and indole-3-pyruvic acid in tryptophan-supplemented nutrient broth. Gluconic, citric and isocitric acids were the major organic acids detected during tricalcium phosphate solubilization. A rifampicin-resistant mutant of the strain exhibited high rhizosphere competence without disturbance to the resident microbial populations in pea rhizosphere. Seed bacterization with a charcoal-based inoculum significantly increased growth in barley, chickpea, pea, and maize under the controlled environment. Microplot testing of the inoculum at two different locations in pea also showed significant increase in growth and yield. The attributes of cold-tolerance, high rhizosphere competence, and broad-spectrum plant growth-promoting activity exhibited the potential of Rahnella sp. BIHB 783 for increasing agriculture productivity.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.10
• /
• pp.1213-1222
• /
• 2009

The search for diverse plant growth-promoting (PGP) diazotrophic bacteria is gaining momentum as efforts are made to exploit them as biofertilizers for various economically important crops. In the present study, 17 diazotrophic strains belonging to eight different genera isolated from rice paddy fields were screened for multiple PGP traits and evaluated for their inoculation effects on canola and rice plants. All of the strains tested positive for 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and production of indole 3-acetic acid (IAA) and ammonia ($NH_3$). Additionally, four of the strains were able to solubilize phosphorus (P), five tested positive for zinc (Zn) solubilization and sulfur (S) oxidation, and eight strains produced siderophores. Based on the presence of multiple PGP traits, 10 strains were selected for inoculation studies. Treatment with Herbaspirillum sp. RFNB26 resulted in maximum root length (54.3%), seedling vigor, and dry biomass in canola, whereas Paenibacillus sp. RFNB4 exhibited the lowest activity under gnotobiotic conditions. However, under pot culture conditions, Paenibacillus sp. RFNB4 significantly increased plant height and dry biomass production by 42.3% and 29.5%, respectively. Canola plants and rhizosphere soils inoculated with Bacillus sp. RFNB6 exhibited significantly higher nitrogenase activity. In greenhouse experiments, Serratia sp. RFNB18 increased rice plant height by 35.1%, Xanthomonas sp. RFNB24 enhanced biomass production by 84.6%, and rice rhizosphere soils inoculated with Herbaspirillum sp. RFNB26 exhibited the highest nitrogenase activity. Our findings indicate that most of the selected strains possess multiple PGP properties that significantly improve the growth parameters of the two plants when tested under controlled conditions.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.7
• /
• pp.1027-1036
• /
• 2020

Stipa purpurea is a unique and dominant herbaceous plant species in the alpine steppe and meadows on the Qinghai-Tibet Plateau (QTP). In this work, we analyzed the composition and diversity of the culturable endophytic fungi in S. purpurea according to morphological and molecular identification. Then, we investigated the bioactivities of these fungi against plant pathogenic fungi and 1-aminocyclopropane-1-carboxylate deaminase (ACCD) deaminase activities. A total of 323 fungal isolates were first isolated from S. purpurea, and 33 fungal taxa were identified by internal transcribed spacer primers and grouped into Ascomycota. The diversity of endophytic fungi in S. purpurea was significantly higher in roots as compared to leaves. In addition, more than 40% of the endophytic fungi carried the gene encoding for the ACCD gene. The antibiosis assay demonstrated that 29, 35, 28, 37 and 34 isolates (43.9, 53.1, 42.4, 56.1, and 51.5%) were antagonistic to five plant pathogenic fungi, respectively. Our study provided the first assessment of the diversity of culture-depending endophytic fungi of S. purpurea, demonstrated the potential application of ACCD activity and antifungal activities with potential benefits to the host plant, and contributed to high biomass production and adaptation of S. purpurea to an adverse environment.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.1
• /
• pp.99-107
• /
• 2009

Strain PUPC1 produces an antifungal protease as well as plant growth promoting enzymes such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase and phosphatase. Morphological, cultural, and physiological characteristics as well as 16S rRNA gene-sequence-based phylogenetic analysis confirmed the taxonomic affiliation of PUPC1 as Chryseobacterium aquaticum. The optimum growth of PUPC1 was observed at pH 6.0 and $30^{\circ}C$, and maximum protease production was observed in medium B amended with 1% tryptone, 0.5% sucrose, and 0.005% $MnCl_2$. The protease was purified by ammonium sulfate precipitation, Sephadex G-75 gel filtration chromatography, and electroelution from preparative SDS-PAGE. The protease had a molecular mass of 18.5 kDa. The optimum pH and temperature stability of the protease were pH 5.0-10.0 and temperature $40-70^{\circ}C$. Chryseobacterium aquaticum PUPC1 and its protease showed a broad-spectrum antifungal activity against phytopathogenic fungi. Strain PUPC1 also exhibited plant growth promoting traits. The objective of the present investigation was to isolate a strain for agricultural application for plant growth promotion and biocontrol of fungal diseases.

• Korean Journal of Microbiology
• /
• v.53 no.4
• /
• pp.251-256
• /
• 2017

Some rhizobacteria were isolated, that have copper resistance and can confer copper resistance to plants allowing growth under copper stress. Isolated strains Pseudomonas veronii MS1 and P. migulae MS2 produced 0.13 and 0.26 mmol/ml of siderophore, that is a metal-chelating agent, and also showed 64.6 and 77.9% of biosorption ability for Cu in 20 mg/L Cu solution, respectively. Copper can catalyze a formation of harmful free radicals, which may cause oxidative stress in organisms. Removal activity of 1,1-diphenyl-2-picryl hydrazyl radical and antioxidant capacity of strains MS1 and MS2 increased up to 82.6 and 78.1%, respectively compared to those of control at 24 h of incubation. They exhibited 7.10 and $6.42{\mu}mol$ ${\alpha}$-ketobutyrate mg/h of 1-aminocyclopropane-1-carboxylic acid deaminase activity, respectively, which reduced levels of stress hormone, ethylene in plants, and also produced indole-3-acetic acid and salicyclic acid that can help plant growth under abiotic stress. All these results indicated that these copper-resistant rhizobacteria could confer copper resistance and growth promotion to plants.

• Korean Journal of Organic Agriculture
• /
• v.26 no.3
• /
• pp.463-475
• /
• 2018

Salinity and extreme temperature stresses affect growth and productivity of crops negatively. Beneficial bacteria, including plant growth-promoting rhizobacteria (PGPR) induce growth promotion and tolerance of plants under abiotic stress conditions. In the present study, 20 strains were selected from 1944 isolated bacteria based on three plant growth-promoting (PGP) traits-aminocyclopropane-1-carboxylate deaminase activity, phosphate solubilization, indole-3-acetic acid production, and growth ability under salinity and extreme temperature stress conditions. Seven among the 20 strains were selected based on growth-promoting effects on plants under saline or temperature stresses in tomato plants. It was expected that the seven strains could induce tolerance of tomato plants under salinity or extreme temperature stresses, which implies that these seven strains can act as potential inducers of multiple stresses tolerance in tomato plants.

• Microbiology and Biotechnology Letters
• /
• v.48 no.1
• /
• pp.38-47
• /
• 2020

This study was conducted to investigate both plant growth-promoting and plant disease- controlling activities of bacterial strains isolated from soil. All the isolated strains were able to grow at various temperatures. All the strains, except ANG40, showed antagonistic effects against various phytopathogenic fungi. This antagonism can be ascribed to the production of siderophores and antibiotic substances. In addition, all the strains showed abilities such as nitrogen fixation, phosphate solubilization, and siderophore production. These results suggest that nitrogen, phosphorus, and iron can be converted into forms that can be easily absorbed by the plants for their growth. Analysis of the growth-promoting properties revealed that ANG51 produced 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and indole-3-acetic acid (IAA) both of which are related to ethylene production. In contrast, the other strains were found to have only IAA-producing ability. Therefore, this study suggests that Pseudomonas geniculata ANG3, Exiguobacterium acetylicum ANG40, and Burkholderia stabilis ANG51, which were selected through analysis of comparative advantages for both plant growth promotion and disease-controlling activity, may be used as biological agents.

• Korean Journal of Soil Science and Fertilizer
• /
• v.44 no.1
• /
• pp.58-66
• /
• 2011

Arsenic pollution is a serious global concern which affects all life forms. Being a toxic metalloid, the continued search for appropriate technologies for its remediation is needed. Phytoremediation, the use of green plants, is not only a low cost but also an environmentally friendly approach for metal uptake and stabilization. However, its application is limited by slow plant growth which is further aggravated by the phytotoxic effect of the pollutant. Attempts to address these constraints were done by exploiting plant-microbe interactions which offers more advantages for phytoremediation. Several bacterial mechanisms that can increase the efficiency of phytoremediation of As are nitrogen fixation, phosphate solubilization, siderophore production, ACC deaminase activity and growth regulator production. Many have been reported for other metals, but few for arsenic. This mini-review attempts to present what has been done so far in exploring plants and their rhizosphere microbiota and some genetic manipulations to increase the efficiency of arsenic soil phytoremediation.