• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.582-592
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• 2012

Microorganisms present in the rhizosphere soil plays a vital role in improving the plant growth and soil fertility. Many kinds of fertilizers including chemical and organic has been approached to improve the productivity. Though some of them showed significant improvement in yield, they failed to maintain the soil properties. Rather they negatively affected soil eventually, the land became unsuitable for agricultural. To overcome these problems, microorganisms have been used as effective alternative. For past few decades, plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) have been used as effective inoculants to enhance the plant growth and productivity. PGPR improves the plant growth and helps the plant to withstand biotic and abiotic stresses. AM fungi are known to colonize roots of plants and they increase the plant nutrient uptake. Spore associated bacteria (SAB) are attached to spore wall or hyphae and known to increase the AMF germination and root colonization but their mechanism of interaction is poorly known. Better understanding the interactions among AMF, SAB and PGPR are necessary to enhance the quality of inoculants as a biofertilizers. In this paper, current knowledge about the interactions between fungi and bacteria are reviewed and discussed about AMF spore associated bacteria.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.246-246
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• 2017

Salinity inhibits plant growth and restricts the efficiency of arbuscular mycorrhizal fungi. The selective uptake of nutrients from the soil and their effective transport to host roots make it essential for plant growth and development under salt stress. AMF spore associated bacteria shown to improve mycorrhizal efficiency under stress. Thus, this study aimed to understand the co-inoculation efficiency of AMF and SAB on maize growth and ion homeostasis under salt stress. Two AMF strains and one SAB were inoculated with maize either alone or in combination with one another. The results of our study showed that AMF and SAB co-inoculation significantly improved dry weight and nutrient uptake of maize under salt stress. Co-inoculation significantly reduced proline accumulation in shoots and Na+ accumulation in roots. Co-inoculation treatment also exhibited the high K+/Na+ ratios in roots at 25 mM NaCl. Mycorrhizal colonization showed positive influence for regulation of ZmAKT2, ZmSOS1 and ZmSKOR gene expressions, contributing to K+ and Na+ ion homeostasis. CLSM view showed that SAB were able move and localize into inter and intra cellular spaces of maize roots. In addition, CLSM view of AMF spores showed that gfp-tagged SAB also associated on the spore outer hyaline layer.

• Journal of Microbiology and Biotechnology
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• v.16 no.2
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• pp.193-199
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• 2006

Halotolerant spore-forming Gram-positive bacteria were isolated from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides. The different isolates were characterized genetically using an amplified ribosomal DNA restriction analysis (ARDRA), and phenotypically based on their colonial morphology, physiology, and nutritional requirements. Three different 16S rRNA gene-based genotypes were observed at a 100% similarity using the enzymes HinfI, MspI, and RsaI, and the phenotypic results also followed the ARDRA groupings. Selected strains, representing the different ARDRA groups, were analyzed by 16S rDNA sequencing, and members of the genera Halobaeillus, Virgibacillus, and Oceanobacillus were found. Two isolates showed low 16S rDNA sequence similarities with the closest related species of Halobacillus, indicating the presence of new species among the isolates. The majority of the strains isolated in this study seemed to belong to the species O. iheyensis and were compared using an AP-PCR to determine whether they had a clonal origin or not. Different patterns allowed the grouping of the strains according to Pearson's coefficient, and the resulting dendrogram revealed the formation of two main clusters, denoted as A and B. All the strains isolated from the soil were grouped into cluster A, whereas cluster B was exclusively composed of the strains associated with the B. portulacoides roots. This is the first report on the isolation and characterization of halotolerant spore-forming Gram-positive bacteria that coexist with B. portulacoides. As such, these new strains may be a potential source for the discovery of bioactive compounds with industrial value.

• International Journal of Industrial Entomology and Biomaterials
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• v.31 no.2
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• pp.107-114
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• 2015

Endophytes provide multifarious benefits such as promotion of plant growth and yield, suppression of phyto-pathogens, phosphate solubilising and fixation nitrogen. A study has been carried out to explore growth promotion and antifungal activities of endophytes of mulberry (Morus spp.). Endophytic bacteria were isolated from mulberry plants and studied their cultural, morphological characters, growth promotion as well as their antifungal activity against Rhizoctonia bataticola and Fusarium oxysporum , two mulberry root rot associated pathogens. Except two isolates, all bacteria were colourless and the colony size of eight isolates was small. The margin of five isolates was irregular and the consistency of three isolates was creamy, six isolates was slimy and one was mucoid. Texture of seven isolates was convex and others were flat. Eight isolates were gram positive and the rest Gram negative, five were cocci and others were bacilli (rod shaped). Four isolates were motile and all were catalase positive and only three isolates were oxidase positive. Spore staining was positive only for two isolates. The growth promotion study showed that there was significant difference in root length and seedling length. The antagonistic effect of the bacterial isolates was tested against R. bataticola showed significant (p <0.05) influence of the bacteria, days after inoculation and their interaction on the inhibition of fungal growth. The isolate En-7 completely inhibited the fungus followed by En-5 (66.67%). The bacterial isolates significantly (p <0.05) inhibited growth of F. oxysporum in PDA. The mean inhibition was higher (70.45%) in case of En-7 followed by En-8 (68.65%) and En-10 (66.44%). The study reveals that some endophytic bacteria associated with mulberry have growth promotion and antifungal activity and could be explored for promotion of mulberry growth and managing root rot disease.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1597-1604
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• 2012

Genus Bacillus is a spore-forming bacterium that has unique properties in cell differentiation, allowing the forming of spores in stress conditions and activated in the vegetative cell, with suitable environments occurring during the life cycle acting as a trigger. Their habitat is mainly in soil; thus, many species of Bacillus are associated with plants as well as rhizosphere bacteria and endophytic bacteria. Signal transduction is the principal mechanism of interactions, both within the cell community and with the external environment, which provides the subsequent functions or properties for the cell. The antimicrobial compounds of Bacillus sp. are potentially useful products, which have been used in agriculture for the inhibition of phytopathogens, for the stimulation of plant growth, and in the food industry as probiotics. There are two systems for the synthesis of these substances: nonribosomal synthesis of cyclic lipopeptides (NRPS) and polyketides (PKS). For each group, the structures, properties, and genes of the main products are described. The different compounds described and the way in which they co-exist exhibit the relationship of Bacillus substances to plants, humans, and animals.

• Preventive Nutrition and Food Science
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• v.7 no.3
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• pp.305-309
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• 2002

Raw soybean sprouts were tested for contamination with the following bacteria which have potential for pathogenesis or food spoilage : Salmonella spp., Escherichia coli O157:H7, Yersinia enterocolitica, Vibrio parahae-molyticus, Aeromonas hydrophila, Plesidomonas shigeloides, Pseudomonas aeruginosa, Staphylococcus aureus, Lis-teria monocytogenes, Bacillus cereus, Clostridium perfringens, Campylobacter jejuni, Erwinia spp., and Fusarium spp. Three of the above strains were isolated from the sprouts, and identified by morphological and biochemical methods including an API kit and ATB automated identification system. The isolate cultured in Cereus selective agar, a selective medium, was a Gram-positive, rod shaped, anaerobic spore former. The biochemical and culture tests revealed the following characteristics: catalase-positive, no growth on Simmon's citrate, NO₂ production and requirement of arginine for growth; the ATB automated identification system gave 99.8 % agreement for the identification of Bacillus cereus to the species level. The isolate cultured in Macconkey agar selective medium was Gram-negative, rod shaped and a gas former; the ATB-system gave 99.9% agreement for the identification of Aeromonas hydrophila to the species level. The isolate found in Pseudomonas isolation agar was Gram-negative, rod shaped, cytochrome oxidase-positive, a reducer of nitrates to nitrogen, and pyocyanin producer; the ATB-system gave 99.9 % agreement for the identification of Pseudomonas aeruginosa to the species level. These results indicate that the three bacteria species present in the soybean sprouts were Bacillus cereus, Aero-monas hydrophila, and Pseudomonas aeruginosa. Salmonella spp., Escherichia coli O157:H7, and Yersinia enter-ocolitica, which are associated with serious disease in humans, were not isolated from soybean sprouts examined in this study.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.110-117
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• 2009

To characterize plant root-associated bacteria in wild plant family Solanaceae, Solanum nigrum L. plants were collected in Dokdo island. Forty four strains of nitrogen-fixing or spore-forming bacteria were isolated from rhizosphere of Solanum nigrum L. plants. Among these, 19 strains were able to produce auxin. Thirteen strains of these produced siderophore as determined by color reaction on CAS-blue plate, 8 strains were able to solubilize phosphate. The 16S rDNA genes of the isolated bacteria were amplified and sequenced. Model plants, pepper and tobacco, were established in order to evaluate the bacterial capacities eliciting growth promotion and induced systemic resistance. The plants treated with strain KUDC1009 were more resistant and capable of growth-promotion than control plants when challenged by either Xanthomonas axonopodis pv. vesicatoria or Erwinia carotovora sub. carotovora strain SCC1. Rhizobacteria isolated from Dokdo island can promote growth of wild type Solanum nigrum L. under much environmental stresses.

• Journal of Microbiology and Biotechnology
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• v.19 no.3
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• pp.314-322
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• 2009

Four different bacterial colonies were isolated from an old stock of an entomopathogenic nematode, Steinernema monticolum. They all showed entomopathogenicity to final instar larvae of beet armyworm, Spodoptera exigua, by hemocoelic injection. However, they varied in colony form, susceptibility to antibiotics, and postmortem change of the infected host insects. Biolog microbial identification and 16S rDNA sequence analyses indicate that these are four different species classified into different bacterial genera. Owing to high entomopathogenicity and a cadaver color of infected insect host, Serratia sp. was selected as a main symbiotic bacterial species and analyzed for its pathogenicity. Although no virulence of Serratia sp. was detected at oral administration, the bacteria gave significant synergistic pathogenicity to fifth instar S. exigua when it was treated along with a spore-forming entomopathogenic bacterium, Bacillus thuringiensis. The synergistic effect was explained by an immunosuppressive effect of Serratia sp. by its high cytotoxic effect on hemocytes of S. exigua, because Serratia sp. caused septicemia of S. exigua when the bacterial cells were injected into S. exigua hemocoel. The cytotoxic factor(s) was present in the culture medium because the sterilized culture broth possessed high potency in the cytotoxicity, which was specific to granular cells and plasmatocytes, two main immune-associated hemocytes in insects.

• Pediatric Infection and Vaccine
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• v.27 no.2
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• pp.127-133
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• 2020

Parvimonas micra is a non-spore-forming anaerobic gram-positive coccus and a known commensal of the skin, gums, vagina, and gastrointestinal tract. It is rarely associated with severe infections, which typically follow invasive procedures such as dental treatment. We describe a case of a brain abscess caused by P. micra in an immunocompetent 11-year-old boy without periodontal disease. He presented with a 7-day history of headaches and vomiting, and complained of diplopia that began on the day of presentation. He did not have any recent dental treatment or specific past medical history. A brain abscess in the left frontoparietal lobe was noted on brain magnetic resonance imaging. P. micra was cultured from brain abscess aspirate. He was successfully treated with surgical drainage and combined antibiotic therapy with ceftriaxone and metronidazole for 6 weeks.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.448-452
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• 2018

The full genome sequence of Bacillus safensis KCTC 12796BP which had been isolated from the marine sponge in the seawater of Jeju Island, was determined by Pac-Bio next-generation sequencing system. A circular chromosome in the length of 3,935,874 bp was obtained in addition to a circular form of plasmid having 36,690 bp. The G + C content of chromosome was 41.4%, and that of plasmid was 37.3%. The number of deduced CDSs in the chromosome was 3,980, whereas 36 CDS regions were determined in a plasmid. Among the deduced CDSs in chromosome, 81 tRNA genes and 24 rRNA genes in addition to one tmRNA were allocated. More than 30 CDSs for sporulation, 16 CDSs for spore coat, and 20 CDSs for germination were also assigned in the chromosome. Several genes for capsular polysaccharide biosynthesis and for flagella biosynthesis and chemotaxis in addition to genes for osmotic tolerance through glycine-choline betaine pathway were also identified. Above all, the biosynthetic gene cluster for anti-allergic compounds seongsanamides were found among two non-ribosomal peptide synthetase (NRPS) gene clusters for secondary metabolites.