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

• Journal of Life Science
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• v.18 no.2
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• pp.255-263
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• 2008

Bacteria that antagonize plant pathogenic fungi were isolated from the sediment soil at the Ansan industrial estate. One isolate of them showed growth inhibition of Rhizoctonia solani, Botrytis cenerea, and Fusarium oxysporum. This strain was identified as Pandoraea sp. based on phenotypic and phylogenetic characteristics and termed Pandoraea sp. BCNU 315. Tryptone as nitrogen source and sucrose as carbon source were found to be most effective for the microbial growth. In addition, the optimum temperature and pH for microbial growth were $30^{\circ}C$ and pH 7.0, respectively. The substances generated from Pandoraea sp. BCNU 315 were purified and analyzed by column chromatography, HPLC, GC-MS and NMR. As a result, one compound was determined to be indole, another compound was predicted as cyclopentadecaheptene. Detailed structural clarification of the all of the rest six compounds from Pandoraea sp. BCNU 315 has to be accompanied in the further studies.

• The Plant Pathology Journal
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• v.33 no.5
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• pp.488-498
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• 2017

The aim of this study was to identify volatile and agardiffusible antifungal metabolites produced by Bacillus sp. G341 with strong antifungal activity against various phytopathogenic fungi. Strain G341 isolated from four-year-old roots of Korean ginseng with rot symptoms was identified as Bacillus velezensis based on 16S rDNA and gyrA sequences. Strain G341 inhibited mycelial growth of all phytopathogenic fungi tested. In vivo experiment results revealed that n-butanol extract of fermentation broth effectively controlled the development of rice sheath blight, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew, and red pepper anthracnose. Two antifungal compounds were isolated from strain G341 and identified as bacillomycin L and fengycin A by MS/MS analysis. Moreover, volatile compounds emitted from strain G341 were found to be able to inhibit mycelial growth of various phytopathogenic fungi. Based on volatile compound profiles of strain G341 obtained through headspace collection and analysis on GC-MS, dimethylsulfoxide, 1-butanol, and 3-hydroxy-2-butanone (acetoin) were identified. Taken together, these results suggest that B. valezensis G341 can be used as a biocontrol agent for various plant diseases caused by phytopathogenic fungi.

• Journal of Microbiology and Biotechnology
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• v.15 no.6
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• pp.1286-1298
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• 2005

The genus Paenibacillus is a new group of bacilli separated from the genus Bacillus, and most of species have been isolated from soil. In the present study, we collected 450 spore-forming bacilli from the roots of winter crops, such as barley, wheat, onion, green onion, and Chinese cabbage, which were cultivated in the southern part of Korea. Among these 450 isolates, 104 Paenibacillus-like isolates were selected, based on their colony shape, odor, color, and endospore morphology, and 41 isolates were then finally identified as Paenibacillus spp. by 16S rDNA sequencing. Among the 41 Paenibacillus isolates, 23 were classified as P. polymyxa, a type species of the genus Paenibacillus, based on comparison of the 16S rDNA sequences with those of 32 type strains of the genus Paenibacillus from the GenBank database. Thirty-five isolates among the 41 Paenibacillus isolates exhibited antagonistic activity towards plant fungal and bacterial pathogens, whereas 24 isolates had a significant growth-enhancing effect on cucumber seedlings, when applied to the seeds. An assessment of the root-colonization capacity under gnotobiotic conditions revealed that all 41 isolates were able to colonize cucumber roots without any significant difference. Twenty-one of the Paenibacillus isolates were shown to contain the nifH gene, which is an indicator of $N_{2}$ fixation. However, the other 20 isolates, including the reference strain E681, did not incorporate the nifH gene. To investigate the diversity of the isolates, a BOX-PCR was performed, and the resulting electrophoresis patterns allowed the 41 Paenibacillus isolates to be divided into three groups (Groups A, B, and C). One group included Paenibacillus strains isolated mainly from barley or wheat, whereas the other two groups contained strains isolated from diverse plant samples. Accordingly, the present results showed that the Paenibacillus isolates collected from the rhizosphere of winter crops were diverse in their biological and genetic characteristics, and they are good candidates for further application studies.

• The Korean Journal of Pesticide Science
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• v.10 no.1
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• pp.56-65
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• 2006

An antagonistic bacterial isolate, that inhibits the growth of plant pathogens, was selected and identified from 5,000 isolates screened from the rhizosphere of various crop plants. An isolate Bacillus sp. N32, tested against Colletotrichum gloeosporioides causing anthracnose disease in hot pepper, produced both a heat resistant antifungal protein and a heat sensitive antifungal protein. The heat resistant protein was partially purified by Ammonium sulfate fractionation and gel filtration chromatography. The bioautography showed that the proteins possessed high antifungal activity. The biosynthetic gene cluster responsible for the heat resistant antifungal protein was cloned from cosmid library using DNA probe obtained from PCR product with the primers targeting the conserved nucleotide sequence of the synthetic genes reported earlier, Most of the clones obtained showed higher homology to fengycin antibiotic synthetic gene family reported earlier. On the other hand, the heat sensitive protein was isolated from SDS-PAGE and electroblotting to determine the N-terminal amino acid sequences. The heat sensitive antifungal protein gene was cloned from the ${\lambda}-ZAP$ libraries using a DNA probe based on the N-terminal amino acid sequences of the heat sensitive protein. We are contemplating to clone and sequence the whole gene cluster encoding the heat sensitive protein for further analysis.

• Korean Journal of Weed Science
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• v.6 no.1
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• pp.67-75
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• 1986

This study was undertaken to investigate the interrelation between herbicide and insecticide and fungicide on rice (Oryza saliva L.) at various growth stages. Carbamate insecticide BPMC (2-sec-butylphenylmethyl-carbamate) severely inhibited germination of rice when applied alone and in combination with herbicides tested. No germination inhibition was obtained with thio- and dithiocarbamate pesticides. Post-germination growth of rice was severely inhibited by the treatments which were combined with BPMC irrespective of herbicides studied. Phytotoxicity of pendimethalin (3,4-dimethyl-2,6-dinitro-N-1-ethyl propylamine) was reduced by antagonistic effect of organophosphorus compounds. When herbicides were applied with either insecticide or fungicide, post-germination growth of rice was more greatly affected by the concentration of herbicides than that of insecticides or fungicides. Most of herbicide-insecticide or herbicide-fungicide treatments did not cause great phytotoxicity on rice when applied 5 days after transplanting. Foliage activity of phenoxy herbicide 2,4-D (2,4-dichlorophenoxy acetic acid) and MCPA [(4-chloro-o-tolyl) oxy acetic acid] increased with addition of carbamate and urea pesticides.

• Korean Journal of Medicinal Crop Science
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• v.28 no.1
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• pp.9-20
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• 2020

Background: Although a number of Panax ginseng cultivars have been developed by Korean researchers in recent years, there has been insufficient analysis of their beneficial properties. In this study, we sought to identify useful ginseng varieties as functional materials. Methods and Results: We evaluated effects of root extracts of 10 ginseng cultivars (Cheongsun; CS, Chunpoong; CP, Gopoong; GP, Gumpoong; GMP, K1, Sunhyang; SH, Sunone; SO, Sunpoong; SP, Sunun; SU and Yunpoong; YP) against the inhibitory effects of nitric oxide (NO) and reactive oxygen species (ROS) production in mouse brain microglial BV2 cells, as well as the binding of N-methyl-D-aspartate receptor (NMDAR), a marker related to memory. Ginsenosides, such as 20 (S)-protopanaxadiols (PPDs), including ginsenoside-Rb1, -Rb2, -Rb3, -Rc, -Rd, and - Rg3 and 20 (S)-protopanaxatriols (PPTs) including -Re, -Rg1, and -Rg2 were analyzed by HPLC. We observed that the cultivar GMP showed the highest inhibitory effect (60.8%) against NO production at 20 ㎍/㎖. Those cultivars showing the significantly highest inhibition effects against ROS at 20 ㎍/㎖ were K1 (57.3%), SP (54.5%), YP (53.1%), CP (51.7%), CS (50.9%) and SH (49.6%). At 50 ㎍/㎖, K1 showed the most potent inhibitory effect (51.2%) on NMDAR binding. The total phenol content of SH (1.89 mg/g) and K1 (1.73 mg/g) were higher than those of the other cultivars, whereas in terms of PD/PT ratios, the values of CP (0.98), K1 (1.05) and SO (1.05) were lower than those of the other cultivars. On the basis of correlation coefficient (0.7064) between NMDAR inhibition and ONOO^- scavenging activity. Conclusions: The findings of this study indicate that the cultivars K1 and SH could be useful ginseng resources as functional materials with favorable cognition-improving and antioxidative properties.

• Journal of Ginseng Research
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• v.40 no.2
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• pp.127-134
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• 2016

Background: Rhizospheric fungi play an essential role in the plantesoil ecosystem, affecting plant growth and health. In this study, we evaluated the fungal diversity in the rhizosphere soil of 2-yr-old healthy Panax notoginseng cultivated in Wenshan, China. Methods: Culture-independent Illumina MiSeq and culture-dependent techniques, combining molecular and morphological characteristics, were used to analyze the rhizospheric fungal diversity. A diffusion test was used to challenge the phytopathogens of P. notoginseng. Results: A total of 16,130 paired-end reads of the nuclear ribosomal internal transcribed spacer 2 were generated and clustered into 860 operational taxonomic units at 97% sequence similarity. All the operational taxonomic units were assigned to five phyla and 79 genera. Zygomycota (46.2%) and Ascomycota (37.8%) were the dominant taxa; Mortierella and unclassified Mortierellales accounted for a large proportion (44.9%) at genus level. The relative abundance of Fusarium and Phoma sequenceswas high, accounting for 12.9% and 5.5%, respectively. In total,113 fungal isolates were isolated from rhizosphere soil. They were assigned to five classes, eight orders (except for an Incertae sedis), 26 genera, and 43 species based on morphological characteristics and phylogenetic analysis of the internal transcribed spacer. Fusarium was the most isolated genus with six species (24 isolates, 21.2%). The abundance of Phoma was also relatively high (8.0%). Thirteen isolates displayed antimicrobial activity against at least one test fungus. Conclusion: Our results suggest that diverse fungi including potential pathogenic ones exist in the rhizosphere soil of 2-yr-old P. notoginseng and that antagonistic isolates may be useful for biological control of pathogens.

• Journal of Dairy Science and Biotechnology
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• v.31 no.2
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• pp.153-159
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• 2013

Lactic acid bacteria are microorganisms that are closely associated with human and/or animal environments, and are categorized as generally recognized as safe (GRAS) organisms due to their ubiquitous appearance in foods and their contribution to the healthy microflora of mucosal surfaces. This study was performed to isolate and identify lactic acid bacteria with antagonistic effects against food-borne pathogens. A total of 3,000 acid-producing bacteria were isolated from infant feces, cattle feces, goat feces, dog feces, pig feces, vaginal tracts, vegetables, fruits, Kimchi, Jeotgal, fermented sausages, raw milk, cheese, yogurt, Cheonggukjang, Meju, and Makgeolli cultured on MRS agar with 0.05% bromocresol purple. For the isolation of bacteriocin-producing bacteria, the diameter of the clear zone was measured on MRS agar plates. Twenty-six isolates exhibited strong antibacterial activity against indicator strains such as Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica serovar Enteritidis. Lactic acid bacteria were identified as Enterococcus faecalis, Enterococcus faecium, Enterococcus hirae, Lactobacillus acidophilus, Lactobacillus amylovorus, Lactobacillus curvatus, Lactobacillus plantarum, and Pediococcus acidilactici by 16S rDNA gene sequence analysis. The results of this study suggest that the isolates could be used as potential probiotic starters for functional food applications.

• Research in Plant Disease
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• v.26 no.1
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• pp.8-18
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• 2020

Red pepper, one of the major economic crops in Korea, is being affected by anthracnose disease caused by Colletotrichum acutatum. To control this disease, an antagonistic bacterial strain, Bacillus subtilis YGB36 identified by 16S rDNA sequencing, physiological and biochemical analyses is used as a biological control agent. In vitro screening revealed that the strain YGB36 possess strong antifungal activity against the pathogen Cylindrocarpon destructans. The strain exhibited cellulase, protease, amylase, siderophore production and phosphate solubility. In vitro conidial germination of C. acutatum was most drastically inhibited by YGB36 cell suspensions (10⁶ cfu/ml) or culture filtrate. Development of anthracnose symptoms was reduced on detached immature green pepper fruits by treatment with cell suspensions, and its control value was recorded as 65.7%. The YGB36 bacterial suspension treatment enhanced the germination rate of red pepper seeds and promoted root development and growth under greenhouse conditions. The in vitro screening of fungicide and insecticide sensitivity test against YGB36 revealed that the bacterial growth was not affected by any of the insecticides, and 11 fungicides out of 21 used. Collectively, our results clearly suggest that the strain YGB36 is considered as one of the potential biocontrol agents against anthracnose disease in red pepper.