Microbacterium elymi sp. nov., Isolated from the Rhizospheric Soil of Elymus tsukushiensis, a Plant Native to the Dokdo Islands, Republic of Korea.

Microbacterium elymi KUDC0405T was isolated from the rhizosphere of Elymus tsukushiensis from the Dokdo Islands. The KUDC0405T strain was Gram-stain-positive, non-spore forming, non-motile, and facultatively anaerobic bacteria. Strain KUDC0405T was a rod-shaped bacterium with size dimensions of 0.3-0.4 × 0.7-0.8 µm. Based on 16S rRNA gene sequences, KUDC0405T was most closely related to Microbacterium bovistercoris NEAU-LLET (97.8%) and Microbacterium pseudoresistens CC-5209T (97.6%). The dDDH (digital DNA-DNA hybridization) values between KUDC0405T and M. bovistercoris NEAU-LLET and M. pseudoresistens CC-5209T were below 17.3% and 17.5%, respectively. The ANI (average nucleotide identity) values among strains KUDC0405T, M. bovistercoris NEAU-LLET, and M. pseudoresistens CC-5209T were 86.6% and 80.7%, respectively. The AAI (average amino acid identity) values were 64.66% and 64.97%, respectively, between KUDC0405T and its closest related type strains. The genome contained 3,596 CDCs, three rRNAs, 46 tRNAs, and three non-coding RNAs (ncRNAs). The genomic DNA GC content was 70.4%. The polar lipids included diphosphatydilglycerol, glycolipid, phosphatydilglycerol, and unknown phospholipid, and the major fatty acids were anteiso-C17:0 and iso-C16:0. Strain KUDC0405T contained MK-12 as the major menaquinone. Based on genotypic, phylogenetic, and phenotypic properties, strain KUDC0405T should be considered a novel species within the genus Microbacterium, for which we propose the name M. elymi sp. nov., and the type strain as KUDC0405T (=KCTC 49411T, =CGMCC1.18472T).

Metabacillus elymi sp. nov., isolated from the Rhizosphere of Elymus tsukushiensis, a plant native to the Dokdo Islands, Republic of Korea.

Dokdo islands in Republic of Korea, is not suited to survive plant because strong wind, low organic content and high salinity. Nevertheless, 64 taxa of plants have a symbiotic relationship with microbe. The Metabacillus elymi KUDC1714T was isolated from the rhizosphere of Elymus tsukushiensis collected from Dokdo Islands. This bacterial strain was Gram-stain positive, non-motile, non-spore forming, aerobic and rod-shape bacteria with 0.4-0.5 × 2.5-3.0 µm in size. Colonies were smooth, yellowish-white circular and 2.0-3.0 mm in diameter. KUDC1714T was capable of growing at 10-45 °C (optimum, 30 °C), pH 7-11 (optimum, pH 8) and 0-8.0% (w/v) NaCl (optimum, 1.0-2.0%). Flagella were not observed by transmission electron microscopy. Phylogenetic analyses, based on 16S rRNA gene sequences, showed that KUDC1714T belonged to the genus Metabacillus formed a phyletic lineage within the genus Metabacillus of the family Bacillaceae. The strain KUDC1714T was most closely related to Metabacillus sediminilitoris DSL-17 T (98.2%), Metabacillus litoralis SW-211 T (98.2%) and Metabacillus halosaccharovorans E33T (97.7%) based on 16S rRNA gene sequence. In silico DNA-DNA hybridization using genome-to-genome distance calculator were analysed at 25.8% and 23.5% in strain KUDC1714T and Metabacillus sediminilitoris DSL-17 T, and strain KUDC1714T and Metabacillus litoralis SW-211 T, respectively. Strain KUDC1714T and its closet type strain were all below cut-off point of the average nucleotide identity and average amino acid identity values. The genome contains 5197 CDSs, 3 rRNAs, 118 tRNAs, 5 ncRNAs. The genomic DNA G + C content was 34.8 mol%. Its polar lipids were diphosphatidylglycerol, phosphatidylglycerol and its major fatty acids were anteiso-C15:0 and iso-C15:0. The strain KUDC1714T contained menaquinone-7 as major isoprenoid quinone. Based on its genetic data, physiological and biochemical characteristics, strain KUDC1714T should be considered a novel species of the genus Metabacillus, for which we propose the name Metabacillus elymi sp. nov. the type strain is KUDC1714T (= KCTC 33222 T, = DSM 27608 T).

Serratia rhizosphaerae sp. nov., a novel plant resistance inducer against soft rot disease in tobacco.

A novel Gram-negative, facultatively anaerobic, non-spore-forming and rod-shaped bacterial strain (KUDC3025T) was isolated from rhizospheric soil of Artemisia japonica subsp. littoricola collected from the Dokdo Islands, Republic of Korea and bacterial strain MYb239 was isolated from compost from Kiel, Germany. Phylogenetic analysis based on 16S rRNA gene sequences, multilocus genes (atpD, gyrB, infB and rpoB), and whole-genome sequences indicated that both strains belonged to the genus Serratia and were most closely related to Serratia rubidaea KCTC 2927T. The average nucleotide identity values based on blast and MUMmer, tetranucleotide usage pattern and genome-based digital DNA-DNA hybridization values were all below the 95.0 %/95.0 %/0.998/70 % cutoff points. The genome G+C content was 58.0 mol%. The cellular quinone content contained ubiquinone-8 and the major components in the fatty acid profile were C16 : 0, C17 : 0 cyclo and C14 : 0. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, four unknown amino lipids, two unknown phospholipids and an unknown lipid. Based on phenotypic, chemotaxonomic and genotypic data, strain KUDC3025T (DSM 106578T=CGMCC 1.18473T) and MYb239 represents a novel species, for which the name Serratia rhizosphaerae sp. nov. is proposed. Furthermore, strain KUDC3025T was able to suppress disease symptoms by priming the plant defence system components, including the salicylic acid and ethylene pathways, furthering our understanding of Serratia as potential plant growth promoting bacteria.

Adhaeribacter radiodurans sp. nov., isolated from the rhizospheric soil of Elymus tsukushiensis, a plant native to the Dokdo Islands, Republic of Korea.

KUDC8001T was isolated from the rhizosperic soil of Elymus tsukushiensis in the Dokdo Islands, Republic of Korea. Strain KUDC8001T was Gram-stain-negative, non-motile and rod-shaped. KUDC8001T was catalase- and oxidase-positive. This strain is capable of growing at 4-37 °C and pH 7.0-8.0 and exhibited optimal growth at 25 °C and pH 7.0. It could be grown in R2A, nutrient agar and ISP2 agar plates. The cell width ranged from 0.7 to 1.0 µm, and length ranged from 2.5 to 5.5 µm. The genomic G+C content was 40.8 mol%. Phylogenetic analysis, based on 16S rRNA gene sequences, revealed that the strain KUDC8001T belongs to the genus Adhaeribacter, which is most closely related to the strain A. pallidiroseus HMF7616T (97.5%). The DNA relatedness of KUDC8001T with the type strains of A. pallidiroseus HMF7616T, A. swui 17 mud1-7T and A. arboris HMF7605T was ≤80.3 % based on average nucleotide identity calculations and ≤86.9 % based on average amino acid identity calculations. In silico DNA-DNA hybridization values of the strain KUDC8001T with the most closely related strains were 22.1, 24.0 and 24.4 %. Based on its phenotypic, phylogenetic, genetic and chemotaxonomic features, the strain KUDC8001T should be considered as a novel species in the genus Adhaeribacter, for which we have proposed the name Adhaeribacter radiodurans sp. nov. The type strain is KUDC8001T (=KCTC 82078T=CGMCC 1.18475T).

Mediation of induced systemic resistance by the plant growth-promoting rhizobacteria Bacillus pumilus S2-3-2.

Plant-rhizobacteria interaction and co-evolution developed adaptive strategies which may help the plant survive in nature. Plant rhizosphere soil isolates were analyzed to investigated the effects of rhizobacteria for promoting plant growth and suppress plant disease. Bacterial strains which isolated from plant rhizosphere soil were screened for elicitation of induced systemic resistance (ISR) on tobacco. Strain S2-3-2 results in significant reduction of disease severity on tobacco, it was identified as Bacillus pumilus by multilocus sequence analysis (MLSA). Strain S2-3-2 was deeper studied for pepper plant growth promotion and biological control activity against pepper bacterial spot disease. It was found that the pepper disease severity was decreased when the roots were drenched with strain S2-3-2, and the pepper plants had a higher weight and chlorophyll content, as compared with the mock-treated plants. Transcriptional expression of pathogenesis-related (PR) protein genes in pepper was analyzed by real-time PCR, gene expressions of CaPR1, CaPR4, and CaPR10 were increased when the plants were treated with strain S2-3-2. Moreover, strain S2-3-2 was tested for the production of indole-3-acetic acid (IAA), and it was determined to emit volatiles that enhance the growth of the tobacco plants. Interesting, heat-killed S2-3-2 enhance the pepper root growth, increase the gene expressions of CaPR4 and CaPR10 after pathogen challenge for 6 h, but limited to suppress the pepper bacterial spot disease as compare to the mock-treated plants. Strain S2-3-2 can be a potential biological control agent on the plant root for plant growth promoting and disease suppression.

Microlunatus elymi sp. nov., a novel actinobacterium isolated from rhizospheric soil of the wild plant Elymus tsukushiensis.

An actinobacterial strain, designated KUDC0627T, was isolated from rhizospheric soil that contained Elymus tsukushiensis on the Dokdo Islands, Republic of Korea. Cells were Gram-stain-positive, facultative anaerobic, non-motile and non-endospore-forming cocci. Results of phylogenetic analysis based on 16S rRNA gene sequences indicated that strain KUDC0627T belongs to the genus Microlunatus and is most closely related to Microlunatus soli DSM 21800T (98.5 %), Microlunatus endophyticus DSM 100019T (97.7 %) and Microlunatus ginsengisoli Gsoil 633T (96.5 %). The average nucleotide identity scores and average amino acid identity values were all below the 95.0 % cut-off point. In silico DNA-DNA hybridization, using the Genome-to-Genome Distance Calculator, estimated that there is 22.3 % DNA relatedness between KUDC0627T and M. soli DSM 21800T. The genomic DNA G+C content was 66.9 mol%. The major menaquinone was MK-9(H4) and the major diagnostic diamino acid in the cell-wall peptidoglycan was ll-diaminopimelic acid. The polar lipid profile included diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipids, unidentified glycolipids and unidentified lipids. The major cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and iso-C16 : 0. Based on phenotypic, chemotaxonomic, and phylogenetic data, strain KUDC0627T (=KCTC 39853T=JCM 32702T) represents a novel species, for which the name Microlunatus elymi sp. nov. is proposed.

Nocardioides sambongensis sp. nov., isolated from Dokdo Islands soil.

Strain KUDC5002T was isolated from soil sampled on the Dokdo Islands, Republic of Korea. This bacterial strain was Gram stain-positive, non-motile, rod-shaped, capable of growing at 25-37°C and pH 5.0-12.0, and showed optimal growth at 30 °C and pH 7.0-8.0. Strain KUDC5002T could be grown in tryptic soy broth containing less than 7.0 % NaCl (w/v). The cell width ranged from 0.5 to 0.6 µm and length ranged from 0.8 to 1.0 µm. Strain KUDC5002T was catalase- and oxidase-positive. Its genomic G+C content was 72.2 mol%. Its major fatty acids were C18 : 1 ω9c (17.3 %), iso-C16 : 0 (16.0 %) and iso-C17 : 0 (11.4 %). Phylogenetic analysis, based on 16S rRNA gene sequences, showed that strain KUDC5002T belongs to the genus Nocardioides and is most closely related to strain Nocardioides humi DCY24T (97.0 %). Based on its phenotypic, phylogenetic, genetic and chemotaxonomic features, strain KUDC5002T should be considered a novel species in the genus Nocardioides, for which we have proposed the name Nocardioides sambongensis sp. nov. The type strain is KUDC5002T (=KCTC 39855T=DSM 106604T).

Bacillus salidurans sp. nov., isolated from salt-accumulated pepper rhizospheric soil.

A Gram-stain-positive, facultatively anaerobic, motile and rod-shaped bacterium, designated KNUC7312T, was isolated from salt-accumulated rhizospheric soil in a pepper greenhouse in Miryang city, Republic of Korea. Cell growth of strain KNUC7312T occurred at 10-45 °C (optimum, 30 °C) and pH 7-12 (optimum, pH 7). In addition, this strain was able to tolerate 0-12 % NaCl (w/v) concentration (optimum, 0-1 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain KNUC7312T clustered together with other species of the genus Bacillus and was most closely related to Bacillus humi DSM 16318T (98.0 %). The predominant respiratory quinone was menaquinone-7 (MK-7). The major cellular fatty acids were anteiso C15 : 0, iso-C15 : 0 and iso-C14 : 0. The polar lipid profile contained the major components diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and two unidentified aminolipids. The cell-wall peptidoglycan contained meso-diaminopimelic acid as the major diagnostic diamino acid. Strain KNUC7312T showed a low DNA-DNA relatedness value (47.36 %) with B. humi DSM 16318T, which supported that this strain represents a novel Bacillusspecies. On the basis of phenotypic, chemotaxonomic and phylogenetic evidence, strain KNUC7312T represents a novel species within the genera Bacillus. The name Bacillus salildurans sp. nov. is proposed. The type strain is KNUC7312T (KCTC 33852T=CGMCC 1.13629T).

Paenibacillus elymi sp. nov., isolated from the rhizosphere of Elymus tsukushiensis, a plant native to the Dokdo Islands, Republic of Korea.

Strain KUDC6143T was isolated from the rhizosphere of Elymus tsukushiensis, a plant native to the Dokdo Islands, Republic of Korea. Cells of this bacterial strain were Gram-positive, endospore-forming, motile and rod-shaped. The strain was capable of growth at a temperature of 25-45 °C and at a pH of 6.0-12.0; it showed an optimal growth at a temperature of 30 °C and at a pH of 7.0. In addition, it grew on a tryptic soy agar and in a tryptic soy broth containing less than 4.0 % NaCl (w/v). The cell length ranged from 2.0 to 2.7 µm. KUDC6143T was catalase-negative and oxidase-positive, and it hydrolysed starch but not casein. Its genomic G+C content was 50.3 mol%. Its major fatty acids were anteiso-C15 : 0, C16 : 0, and iso-C16 : 0. Phylogenetic analysis, based on the 16S rRNA gene sequences, showed that KUDC6143T belonged to the genus Paenibacillus, with the most closely related type strain being Paenibacillus pinihumi S23T (97.8 %). Based on its phenotypic characteristics, phylogenetic data and genetic data, strain KUDC6143T should be considered as representing a novel species of the genus Paenibacillus, for which we propose the name Paenibacillus elymi sp. nov. The type strain is KUDC6143T (=KCTC 33853T=DSM 106581T).

Exogenous application of phenylacetic acid promotes root hair growth and induces the systemic resistance of tobacco against bacterial soft-rot pathogen Pectobacterium carotovorum subsp. carotovorum.

Phenylacetic acid (PAA) was evaluated for its capability to promote plant growth and induce systemic resistance in tobacco (Nicotianum tabacum L cv. Xanthi) against the bacterial soft rot pathogen Pectobacterium carotovorum subsp. carotovorum (PCC). Exogenous application of PAA influenced root formation, the activities of defence-related enzymes and the expression of defence and growth-related genes. Increased formation of lateral roots can be observed in tobacco treated with higher PAA concentrations. The highest elicitation of induced systemic resistance (ISR) was found in plants treated with 0.5mM PAA, where the phytotoxic effect was minimal. The activities of the defence enzymes phenylalanine ammonia-lyase (PAL), peroxidase (POD) and polyphnenoloxidase (PPO) were modulated upon treatment with different PAA concentrations. Reverse transcription-PCR analyses showed that 0.5mM PAA modulated the expression of the growth-related genes NtEXP2 and NtEXP6, and the defence-related genes Coi1, NPR1, PR-1a and PR-1b. These results showed that different concentrations of PAA can elicit different responses and effects on tobacco growth and resistance. This study presents the important role of PAA not only on plant growth but also for plant immunity against phytopathogens.

Cutaneous Microflora from Geographically Isolated Groups of Bradysia agrestis, an Insect Vector of Diverse Plant Pathogens.

Larvae of Bradysia agrestis, an insect vector that transports plant pathogens, were sampled from geographically isolated regions in Korea to identify their cutaneous fungal and bacterial flora. Sampled areas were chosen within the distribution range of B. agrestis; each site was more than 91 km apart to ensure geographical segregation. We isolated 76 microbial (fungi and bacteria) strains (site 1, 29; site 2, 29; site 3, 18 strains) that were identified on the basis of morphological differences. Species identification was molecularly confirmed by determination of universal fungal internal transcribed spacer and bacterial 16S rRNA gene sequences in comparison to sequences in the EzTaxon database and the NCBI GenBank database, and their phylogenetic relationships were determined. The fungal isolates belonged to 2 phyla, 5 classes, and 7 genera; bacterial species belonged to 23 genera and 32 species. Microbial diversity differed significantly among the geographical groups with respect to Margalef's richness (3.9, 3.6, and 4.5), Menhinick's index (2.65, 2.46, and 3.30), Simpson's index (0.06, 0.12, and 0.01), and Shannon's index (2.50, 2.17, and 2.58). Although the microbial genera distribution or diversity values clearly varied among geographical groups, common genera were identified in all groups, including the fungal genus Cladosporium, and the bacterial genera Bacillus and Rhodococcus. According to classic principles of co-evolutionary relationship, these genera might have a closer association with their host insect vector B. agrestis than other genera identified. Some cutaneous bacterial genera (e.g., Pseudomonas) displaying weak interdependency with insect vectors may be hazardous to agricultural environments via mechanical transmission via B. agrestis. This study provides comprehensive information regarding the cutaneous microflora of B. agrestis, which can help in the control of such pests for crop management.

Foodborne Infectious Diseases Mediated by Inappropriate Infection Control in Food Service Businesses and Relevant Countermeasures in Korea.

OBJECTIVES: The objective of this review is to propose an appropriate course of action for improving the guidelines followed by food handlers for control of infection. For this purpose, previous epidemiological reports related to acute gastroenteritis in food service businesses mediated by food handlers were intensively analyzed. METHODS: Relevant studies were identified in international databases. We selected eligible papers reporting foodborne infectious disease outbreaks. Among primary literature collection, the abstract of each article was investigated to find cases that absolutely identified a causative factor to be food handlers' inappropriate infection control and the taxon of causative microbial agents by epidemiological methodologies. Information about the sites (type of food business) where the outbreaks occurred was investigated. RESULTS: A wide variety of causative microbial agents has been investigated, using several epidemiological methods. These agents have shown diverse propagation pathways based on their own molecular pathogenesis, physiology, taxonomy, and etiology. CONCLUSION: Depending on etiology, transmission, propagation, and microbiological traits, we can predict the transmission characteristics of pathogens in food preparation areas. The infected food workers have a somewhat different ecological place in infection epidemiology as compared to the general population. However, the current Korean Food Safety Act cannot propose detailed guidelines. Therefore, different methodologies have to be made available to prevent further infections.

Alleviation of Salt Stress in Pepper (Capsicum annum L.) Plants by Plant Growth-Promoting Rhizobacteria.

In the present study, we demonstrate that the growth of salt-stressed pepper plants is improved by inoculation with plant growth-promoting rhizobacteria (PGPR). Three PGPR strains (Microbacterium oleivorans KNUC7074, Brevibacterium iodinum KNUC7183, and Rhizobium massiliae KNUC7586) were isolated from the rhizosphere of pepper plants growing in saline soil, and pepper plants inoculated with these PGPR strains exhibited significantly greater plant height, fresh weight, dry weight, and total chlorophyll content than non-inoculated plants. In addition, salt-stressed pepper plants that were inoculated with B. iodinum KNUC7183 and R. massiliae KNUC7586 possessed significantly different total soluble sugar and proline contents from non-inoculated controls, and the activity of several antioxidant enzymes (ascorbate peroxidase, guaiacol peroxidase, and catalase) was also elevated in PGPR-treated plants under salt stress. Overall, these results suggest that the inoculation of pepper plants with M. oleivorans KNUC7074, B. iodinum KNUC7183, and R. massiliae KNUC7586 can alleviate the harmful effects of salt stress on plant growth.

Paenibacillus aceris sp. nov., isolated from the rhizosphere of Acer okamotoanum, a plant native to Ulleungdo Island, Republic of Korea.

Strain KUDC4121T was isolated from the rhizosphere of Acer okamotoanum, a plant native to the Korean island of Ulleungdo. The strain was a Gram-stain-positive, non-spore-forming, non-motile, rod-shaped bacterium that can grow at 18-37 °C and pH 6.0-7.5, with optimum growth at 30 °C and pH 7.0. It grew on tryptic soy agar containing less than 0.5 % (w/v) NaCl and in R2A broth. Cell length ranged from 2.0 to 2.5 µm. Strain KUDC4121T was oxidase- and catalase-positive and did not hydrolyse starch or casein. The genomic G+C content was 48.8 mol%. The major fatty acids were anteiso-C15 : 0 and iso-C16 : 0. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain KUDC4121T belongs to the genus Paenibacillus. The closest type strain was Paenibacillus chondroitinus DSM 5051T, with 97.8 % similarity, followed by Paenibacillus alginolyticus DSM 5050T (97.6 %), Paenibacillus ferrarius CY1T (97.5 %), Paenibacillus pocheonensis Gsoil 1138T (97.5 %), Paenibacillus frigoriresistens YIM 016T (97.5 %), Paenibacillus pectinilyticus RCB-08T (97.2 %) and Paenibacillus aestuarii CJ25T (96.9 %). Based on its phenotypic properties and phylogenetic and genetic data, strain KUDC4121T should be considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus aceris sp. nov. is proposed. The type strain is KUDC4121T (=KCTC 13870T=DSM 24950T).

Comparative study of rhizobacterial communities in pepper greenhouses and examination of the effects of salt accumulation under different cropping systems.

This study compared rhizobacterial communities in pepper greenhouses under a paddy-upland (rice-pepper) rotational system (PURS) and a monoculture repeated cropping system (RCS) and examined adverse effects of high salinity on soil properties. The following soil properties were analyzed: electrical conductivity (EC), pH, concentration of four cations (Na, Ca, Mg, and K), total nitrogen, and organic matter content. Rhizobacterial communities were analyzed using culture-based and culture-independent (pyrosequencing) methods. In addition, all culturable bacteria isolated from each soil sample were tested for traits related to plant growth promotion. The EC of rhizospheric soils was 5.32-5.54 dS/m for the RCS and 2.05-2.19 dS/m for the PURS. The culture-based method indicated that the bacterial communities and bacterial characteristics were significantly more diverse in the PURS soil than in the RCS soil. The pyrosequencing data also indicated that the richness and diversity of bacterial communities were greater in the PURS soil. Proteobacteria was the most abundant phylum in soil samples under both cropping systems. However, Firmicutes and Gemmatimonadetes were more prevalent in the RCS soil, while the PURS soil contained a greater number of Chloroflexi. Spearman's correlation coefficients showed that soil EC was significantly positively correlated with the abundance of Firmicutes and Gemmatimonadetes and negatively correlated with the abundance of Acidobacteria, Chloroflexi, and Deltaproteobacteria. This is the first study on the rhizobacterial communities in pepper greenhouses under two different cropping systems using both culture- and pyrosequencing-based methods.

Impact of a Bacterial Volatile 2,3-Butanediol on Bacillus subtilis Rhizosphere Robustness.

Volatile compounds, such as short chain alcohols, acetoin, and 2,3-butanediol, produced by certain strains of root-associated bacteria (rhizobacteria) elicit induced systemic resistance in plants. The effects of bacterial volatile compounds (BVCs) on plant and fungal growth have been extensively studied; however, the impact of bacterial BVCs on bacterial growth remains poorly understood. In this study the effects of a well-characterized bacterial volatile, 2,3-butanediol, produced by the rhizobacterium Bacillus subtilis, were examined in the rhizosphere. The nature of 2,3-butanediol on bacterial cells was assessed, and the effect of the molecule on root colonization was also determined. Pepper roots were inoculated with three B. subtilis strains: the wild type, a 2,3-butanediol overexpressor, and a 2,3-butanediol null mutant. The B. subtilis null strain was the first to be eliminated in the rhizosphere, followed by the wild-type strain. The overexpressor mutant was maintained at roots for the duration of the experiment. Rhizosphere colonization by a saprophytic fungus declined from 14 days post-inoculation in roots treated with the B. subtilis overexpressor strain. Next, exudates from roots exposed to 2,3-butanediol were assessed for their impact on fungal and bacterial growth in vitro. Exudates from plant roots pre-treated with the 2,3-butanediol overexpressor were used to challenge various microorganisms. Growth was inhibited in a saprophytic fungus (Trichoderma sp.), the 2,3-butanediol null B. subtilis strain, and a soil-borne pathogen, Ralstonia solanacearum. Direct application of 2,3-butanediol to pepper roots, followed by exposure to R. solanacearum, induced expression of Pathogenesis-Related (PR) genes such as CaPR2, CaSAR8.2, and CaPAL. These results indicate that 2,3-butanediol triggers the secretion of root exudates that modulate soil fungi and rhizosphere bacteria. These data broaden our knowledge regarding bacterial volatiles in the rhizosphere and their roles in bacterial fitness and as important inducers of plant defenses.

Bowmanella dokdonensis sp. nov., a novel exoelectrogenic bacterium isolated from the seawater of Dokdo, Korea.

A Gram-negative, motile, and rod-shaped bacterial strain, UDC354(T), was isolated from the seawater of Dokdo, Korea. The strain UDC354(T) displayed optimal growth at 30-37 °C in the presence of 0-2 % (w/v) NaCl at pH 8. Strain UDC354(T) was found to contain Q-8 and 9 as isoprenoid ubiquinones; C16:0 (22.9 %), summed feature 3 (iso-C15:0 2-OH and C16:1 ω7c) (21.4 %) and C18:1 ω7c (12.2 %) as the major fatty acids; and diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine as the major polar lipids. The DNA G+C content was found to be 54.1 mol %. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain UDC354(T) belongs to the genus Bowmanella, of the family Alteromonadaceae, and is closely related to Bowmanella pacifica W3-3A(T) (95.2 %) and Bowmanella denitrificans BD1(T) (95.0 %). It was found that strain UDC354(T) is exoelectrogenic and is capable of generating 6.6 µW/cm(3) in marine broth in the microbial fuel cells. Based on the analysis of the phenotypic, chemotypic and phylogenetic characteristics, a new species, Bowmanella dokdonensis sp. nov. is proposed. The type strain is UDC354(T) (=KCTC 42147(T)=JCM 30855(T)).

Lutibacter oricola sp. nov., a marine bacterium isolated from seawater.

A bacterial strain, UDC377(T), was isolated from seawater samples collected at Seo-do on the coast of Dokdo island in the East Sea, and was subjected to taxonomic study using a polyphasic approach. Strain UDC377(T) was pale-yellow, Gram-staining-negative, non-motile, rod-shaped and aerobic. The strain grew optimally at 25-28 °C, in the presence of 2 % (w/v) NaCl and at pH 7.0-7.5. Strain UDC377(T) produced carotenoid pigments; however, it did not produce flexirubin-type pigments. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain UDC377(T) clustered with members of the genus Lutibacter and appeared most closely related to Lutibacter agarilyticus KYW566(T) (96.0 % 16S rRNA gene sequence similarity) followed by L. aestuarii MA-My1(T) (95.0 %), L. litoralis CL-TF09(T) (94.9 %), L. maritimus S7-2(T) (94.1 %) and L. flavus IMCC1507(T) (94.0 %). The DNA G+C content of strain UDC377(T) was 30.8 mol%. Strain UDC377(T) contained MK-6 as the predominant menaquinone, iso-C15 : 0 3-OH, iso-C15 : 0 and iso-C16 : 0 3-OH as the major fatty acids, and phosphatidylethanolamine, two unknown aminolipids and six unknown lipids as the major polar lipids. Based on phenotypic properties and phylogenetic data presented, strain UDC377(T) is considered to represent a novel species of the genus Lutibacter, for which the name Lutibacter oricola sp. nov. is proposed. The type strain is UDC377(T) ( = DSM 24956(T) = KCTC 23668(T)).

Linoleic acid-induced expression of defense genes and enzymes in tobacco.

Linoleic acid (LA) is a naturally occurring fatty acid (FA) found to elicit induced systemic resistance (ISR) of tobacco against the bacterial soft rot pathogen, Pectobacterium carotovorum subsp. carotovorum (PCC). In this study, we examined effects of six doses of exogenous LA on the induction of defense genes and enzymes. The optimum ISR activity was observed in plants treated with 0.1mM LA where the effect of LA on membrane permeability was minimal. The application of LA as a root drench enhanced the activity of defense enzymes such as phenylalanine ammonia-lyase (PAL), peroxidase (POD), and polyphenol oxidase (PPO) and induced the expression of ß-glucuronidase (GUS). PAL and POD activities were increased in a concentration dependent manner while the maximum PPO activity was observed after treatment with 0.01mM LA. An RT-PCR analysis of the defense-related genes, Coi1, NPR1, PR-1a and PR-1b, of tobacco plants treated with 0.1mM LA revealed an association of LA with elicitation of ISR in tobacco.

Paenibacillus dongdonensis sp. nov., isolated from rhizospheric soil of Elymus tsukushiensis.

A Gram-staining-positive, endospore-forming and rod-shaped bacterial strain, designated KUDC0114(T), was isolated from rhizospheric soil of Elymus tsukushiensis from Dongdo Island, one of the largest of the Dokdo Islands, South Korea. The strain displayed optimal growth at 37 °C, pH 8.5 in the absence of NaCl. Based on phylogenetic analysis of 16S rRNA gene sequences, strain KUDC0114(T) represented a member of the genus Paenibacillus and was most closely related to Paenibacillus taichungensis BCRC 17757(T) (98.46%). The cell-wall peptidoglycan was A1γ type, and the predominant quinone was menaquinone-7 (MK-7). The major cellular fatty acids were anteiso-C(15 : 0) and C(16 : 0). The DNA-DNA hybridization of strain KUDC0114(T) with nine other strains indicated less than 23% relatedness, and its DNA G+C content was 44.30 mol%. Based on genomic, phenotypic and phylogenetic analyses, KUDC0114(T) should be classified as representing novel species within the genus Paenibacillus. The name Paenibacillus dongdonensis sp. nov. is proposed. The type strain is KUDC0114(T) ( = DSM27607(T) = KCTC33221(T)).