Journal of Microbiology

Volume 53(7); July 2015

Review

MINIREVIEW] Indole: a signaling molecule or a mere metabolic byproduct that alters bacterial physiology at a high concentration?: Jisun Kim , Woojun Park; J. Microbiol. 2015;53(7):421-428. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5273-3

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Abstract: Indole is an organic compound that is widespread in microbial communities inhabiting diverse habitats, like the soil environment and human intestines. Measurement of indole production is a traditional method for the identification of microbial species. Escherichia coli can produce millimolar concentrations of indole in the stationary growth phase under nutrient-rich conditions. Indole has received considerable attention because of its remarkable effects on various biological functions of the microbial communities, for example, biofilm formation, motility, virulence, plasmid stability, and antibiotic resistance. Indole may function as an intercellular signaling molecule, like a quorum-sensing signal. Nevertheless, a receptor system for indole and the function of this compound in coordinated behavior of a microbial population (which are requirements for a true signaling molecule) have not yet been confirmed. Recent findings suggest that a long-known quorum-sensing regulator, E. coli’s SdiA, cannot recognize indole and that this compound may simply cause membrane disruption and energy reduction, which can lead to various changes in bacterial physiology including unstable folding of a quorum-sensing regulator. Indole appears to be responsible for acquisition of antibiotic resistance via the formation of persister cells and activation of an exporter. This review highlights and summarizes the current knowledge about indole as a multitrophic molecule among bacteria, together with recently identified new avenues of research.

Research Support, Non-U.S. Gov'ts

Spirosoma montaniterrae sp. nov., an ultraviolet and gamma radiation-resistant bacterium isolated from mountain soil: Jae-Jin Lee , Myung-Suk Kang , Eun Sun Joo , Myung Kyum Kim , Wan-Taek Im , Hee-Young Jung , Sathiyaraj Srinivasan; J. Microbiol. 2015;53(7):429-434. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5008-5

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Abstract: A Gram-negative, yellow-pigmented, long-rod shaped bacterial strain designated DY10T was isolated from a soil sample collected at Mt. Deogyusan, Jeonbuk province, South Korea. Optimum growth observed at 30°C and pH 7. No growth was observed above 1% (w/v) NaCl. Comparative 16S rRNA gene sequence analysis showed that strain DY10T belonged to the genus Spirosoma and was distantly related to Spirosoma arcticum R2-35T (91.0%), Spirosoma lingual DSM 74T (90.8%), Spirosoma endophyticum EX36T (90.7%), Spirosoma panaciterrae DSM 21099T (90.5%), Spirosoma rigui WPCB118T (90.2%), Spirosoma spitsbergense DSM 19989T (89.8%), Spirosoma luteum DSM 19990T (89.6%), Spirosoma oryzae RHs22T (89.6%), and Spirosoma radiotolerans DG5AT (89.1%). Strain DY10T showed resistance to gamma and ultraviolet radiation. The chemotaxonomic characteristics of strain DY10T were consistent with those of the genus Spirosoma, with the quinone system with MK-7 as the predominant menaquinone, iso-C15:0, C16:1 ω5c, and summed feature3 (C16:1 ω7c/C16:1 ω6c), and phosphatidylethanolamine as the major polar lipid. The G+C content of the genomic DNA was 53.0 mol%. Differential phenotypic properties with the closely related type strains clearly distinguished strain DY10T from previously described members of the genus Spirosoma and represents a novel species in this genus, for which the name Spirosoma montaniterrae sp. nov. is proposed. The type strain is DY10T (=KCTC 23999T =KEMB 9004-162T =JCM 18492T).

Sphingosinicella ginsenosidimutans sp. nov., with ginsenoside converting activity: Jin-Kwang Kim , Myung-Suk Kang , Sung Chul Park , Kyeng-Min Kim , Kangduk Choi , Min-Ho Yoon , Wan-Taek Im; J. Microbiol. 2015;53(7):435-441. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5087-3

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Abstract: The Gram-reaction-negative, strictly aerobic, non-motile, nonspore- forming, and rod-shaped bacterial strain designated BS11T was isolated from the compost and its taxonomic position was investigated by using a polyphasic approach. Strain BS11T grew optimally at 30?7캜 and at pH 7.0 in the absence of NaCl on nutrient agar. Strain BS11T displayed ?glucosidase activity that was responsible for its ability to transform ginsenoside Rb1 (one of the dominant active components of ginseng) to Rd. On the basis of 16S rRNA gene sequence similarity, strain BS11T was shown to belong to the family Sphingomonadaceae and was related to Sphingosinicella vermicomposti YC7378T (96.3% sequence similarity), S. xenopeptidilytica 3-2W4T (96.2%), S. microcystinivorans Y2T (96.1%), and S. soli KSL-125 T (95.9%). The G+C content of the genomic DNA was 64.9%. The major menaquinone was Q-10 and the major fatty acids were summed feature 7 (comprising C18:1 ?c/?t/?2t; 40.6%), C16:0 (22.5%), C17:1 ?c (13.7%) and C17:0 (9.1%). DNA and chemotaxonomic data supported the affiliation of strain BS11T to the genus Sphingosinicella. Strain BS11T could be differentiated genotypically and phenotypically from the recognized species of the genus Sphingosinicella. The novel isolate therefore represents a novel species, for which the name Sphingosinicella ginsenosidimutans sp. nov. is proposed, with the type strain BS11T (=KACC 16619T =JCM 18201T).

Flavisolibacter swuensis sp. nov. Isolated from Soil: Eun Sun Joo , Seho Cha , Myung Kyum Kim , Weonhwa Jheong , Taegun Seo , Sathiyaraj Srinivasan; J. Microbiol. 2015;53(7):442-447. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5241-y

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Abstract: A Gram-staining-negative, non-motile, non-spore-forming, and rod-shaped bacterium designated as strain SR2-4-2T was isolated from soil in South Korea. Phylogenetic analysis based on 16S rRNA gene sequence of strain SR2-4-2T revealed that it belonged to the genus of Flavisolibacter, family of Chitinophagaceae, and class of Sphingobacteriia. It shared sequence similarities with Flavisolibacter ginsengisoli Gsoil 643T (96.4%), Flavisolibacter ginsengiterrae Gsoil 492T (96.3%), and Flavisolibacter rigui 02SUJ3T (93.0%). Chemotaxonomic data revealed that its predominant fatty acids were iso-C15:0 (26.4%) and iso-C17:0 3OH (10.7%). Its major polar lipid was phosphatidylethanolamine (PE) and its predominant respiratory quinone was MK-7. The G+C content of genomic DNA of the strain SR2-4-2T DNA was 45.0%. Based on the phylogenetic, chemotaxonomic, and phenotypic data, the strain SR2-4-2T (=JCM 19974T =KEMB 9004-156T) is classified as a type strain of a novel species for which the name of Flavisolibacter swuensis sp. nov. is proposed.

Bacillus coreaensis sp. nov.: a xylan-hydrolyzing bacterium isolated from the soil of Jeju Island, Republic of Korea: Won-Jae Chi , Young Sang Youn , Jae-Seon Park , Soon-Kwang Hong; J. Microbiol. 2015;53(7):448-453. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5140-2

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Abstract: A xylan-degrading bacterium, designated as MS5T strain, was isolated from soil collected from the Jeju Island, Republic of Korea. Strain MS5T was Gram-stain-positive, aerobic, and motile by polar flagellum. The major fatty acids identified in this bacterium were iso-C15:0 (32.3%), C16:0 (27.3%), and anteiso-C15:0 (10.2%). A similarity search based on the 16S rRNA gene sequence revealed that the strain belongs to the class Bacilli and shared the highest similarity with the type strains Bacillus beringensis BR035T (98.7%) and Bacillus korlensis ZLC-26T (98.6%) which form a coherent cluster in a neighbor-joining phylogenetic tree. The DNA G+C content of strain MS5T was 43.0 mol%. The major menaquinone was MK-7 and the diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The DNADNA relatedness values between strain MS5T and two closely related species, B. beringensis BR035T and B. korlensis ZLC- 26T, were less than 70%. DNA-DNA relatedness analysis and 16S rRNA sequence similarity, as well as phenotypic and chemotaxonomic characteristics suggest that the strain MS5T constitutes a novel Bacillus species, for which the name Bacillus coreaensis sp. nov. is proposed. The type strain is MS5T (=DSM25506T =KCTC13895T).

Arbuscular mycorrhizal fungal diversity, root colonization, and soil alkaline phosphatase activity in response to maize-wheat rotation and no-tillage in North China: Junli Hu , Anna Yang , Anning Zhu , Junhua Wang , Jue Dai , Ming Hung Wong , Xiangui Lin; J. Microbiol. 2015;53(7):454-461. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5108-2

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Abstract: Monitoring the effects of no-tillage (NT) in comparison with conventional tillage (CT) on soil microbes could improve our understanding of soil biochemical processes and thus help us to develop sound management strategies. The objective of this study was to compare the species composition and ecological function of soil arbuscular mycorrhizal (AM) fungi during the growth and rotation of crops under NT and CT. From late June 2009 to early June 2010, 32 topsoil (0쭯15 cm) samples from four individual plots per treatment (CT and NT) were collected at both the jointing and maturation stages of maize (Zea mays L.) and wheat (Triticum aestivum L.) from a long-term experimental field that was established in an Aquic Inceptisol in North China in June 2006. The AM fungal spores were isolated and identified and then used to calculate species diversity indices, including the Shannon- Wiener index (H▽), Evenness (E), and Simpson’s index (D). The root mycorrhizal colonization and soil alkaline phosphatase activity were also determined. A total of 34 species of AM fungi within nine genera were recorded. Compared with NT, CT negatively affected the soil AM fungal community at the maize sowing stage, leading to decreases in the average diversity indices (from 2.12, 0.79, and 0.82 to 1.79, 0.72, and 0.74 for H▽, E, and D, respectively), root mycorrhizal colonization (from 28% to 20%), soil alkaline phosphatase activity (from 0.24 to 0.19 mg/g/24 h) and available phosphorus concentration (from 17.4 to 10.5 mg/kg) at the maize jointing stage. However, reductions in diversity indices of H▽, E, and D were restored to 2.20, 0.81, and 0.84, respectively, at the maize maturation stage. CT should affect the community again at the wheat sowing stage; however, a similar restoration in the species diversity of AM fungi was completed before the wheat jointing stage, and the highest Jaccard index (0.800) for similarity in the species composition of soil AM fungi between CT and NT was recorded at the wheat maturation stage. Our results also demonstrated that NT resulted in the positive protection of the community structure of AM fungi and played an important role in maintaining their functionality especially for maize seedlings.

Journal Article

Biotransformation of (-)-α-pinene and geraniol to α-terpineol and p-menthane-3,8-diol by the white rot fungus, Polyporus brumalis: Su-Yeon Lee , Seon-Hong Kim , Chang-Young Hong , Se-Yeong Park , In-Gyu Choi; J. Microbiol. 2015;53(7):462-467. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5081-9

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Abstract: In this study, the monoterpenes, α-pinene and geraniol, were biotransformed to synthesize monoterpene alcohol compounds. Polyporus brumalis which is classified as a white rot fungus was used as a biocatalyst. Consequently α-terpineol was synthesized from α-pinene by P. brumalis mycelium, after three days. Moreover, another substrate, the acyclic monoterpenoids geraniol was transformed into the cyclic compound, p-menthane-3, 8-diol (PMD). The main metabolites, i.e., α-terpineol and PMD, are known to be bioactive monoterpene alcohol compounds. This study highlights the potential of fungal biocatalysts for monoterpene transformation.

Research Support, Non-U.S. Gov'ts

Anti-tumor effect of Cordyceps militaris in HCV-infected human hepatocarcinoma 7.5 cells: Seulki Lee , Hwan Hee Lee , Jisung Kim , Joohee Jung , Aree Moon , Choon-Sik Jeong , Hyojeung Kang , Hyosun Cho; J. Microbiol. 2015;53(7):468-474. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5198-x

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Abstract: Cordyceps extract has been reported to have various pharmacological activities including an anti-cancer effect. We investigated the inhibitory effect of Cordyceps militaris on hepatitis C virus-infected human hepatocarcinoma 7.5 cells (J6/JFH1-huh 7.5 cells). The huh7.5 cells with or without HCV infection were treated with various concentrations of ethanol extract of Cordyceps militaris (CME) for 48 h and the cytotoxicity was measured by CCK-8 assay. Both J6/JFH1- huh7.5 cells and huh7.5 cells were highly susceptible to CME. To examine the molecular mechanisms of the inhibitory effect on huh7.5 cells, the effect of CME on cell apoptosis was measured using flow cytometry and the expressions of p53, Bim, Bax, PARP, (cleaved) caspase-9, and (cleaved) caspase- 3 in huh 7.5 cells were detected by western blot assays. CME significantly increased early apoptosis and up-regulated the expression of Bim, Bax, cleaved PARP, cleaved caspase 9 and cleaved caspase-3. We also found the decrease of HCV Core or NS3 protein by CME in HCV-infected huh 7.5 cells.

Prevalence of avian influenza virus in wild birds before and after the HPAI H5N8 outbreak in 2014 in South Korea: Jeong-Hwa Shin , Chanjin Woo , Seung-Jun Wang , Jipseol Jeong , In-Jung An , Jong-Kyung Hwang , Seong-Deok Jo , Seung Do Yu , Kyunghee Choi , Hyen-Mi Chung , Jae-Hwa Suh , Seol-Hee Kim; J. Microbiol. 2015;53(7):475-480. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5224-z

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Abstract: Since 2003, highly pathogenic avian influenza (HPAI) virus outbreaks have occurred five times in Korea, with four HPAI H5N1 outbreaks and one HPAI H5N8 outbreak. Migratory birds have been suggested to be the first source of HPAI in Korea. Here, we surveyed migratory wild birds for the presence of AI and compared regional AI prevalence in wild birds from September 2012 to April 2014 for birds having migratory pathways in South Korea. Finally, we investigated the prevalence of AI in migratory birds before and after HPAI H5N8 outbreaks. Overall, we captured 1617 migratory wild birds, while 18,817 feces samples and 74 dead birds were collected from major wild bird habitats. A total of 21 HPAI viruses were isolated from dead birds, and 86 low pathogenic AI (LPAI) viruses were isolated from captured birds and from feces samples. Spatiotemporal distribution analysis revealed that AI viruses were spread southward until December, but tended to shift north after January, consistent with the movement of migratory birds in South Korea. Furthermore, we found that LPAI virus prevalences within wild birds were notably higher in 2013?014 than the previous prevalence during the northward migration season. The data from our study demonstrate the importance of the surveillance of AI in wild birds. Future studies including in-depth genetic analysis in combination with evaluation of the movement and ecology of migratory birds might help us to bridge the gaps in our knowledge and better explain, predict, and ultimately prevent future HPAI outbreaks.

Development of a stringent ELISA protocol to evaluate anti-viral hemorrhagic septicemia virus-specific antibodies in olive flounder Paralichthys olivaceus with improved specificity: Hyoung Jun Kim , Jeong Su Park , Se Ryun Kwon; J. Microbiol. 2015;53(7):481-485. Published online June 27, 2015; DOI: https://doi.org/10.1007/s12275-015-5101-9

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Abstract: Olive flounder were vaccinated with polyinosinic:polycytidylic acid [Poly (I:C)] to prevent viral hemorrhagic septicemia (VHS). Vaccine efficacy was verified by detection of anti- VHS virus (VHSV) antibodies using enzyme-linked immunosorbent assay (ELISA). In the study, ELISA absorbance values of the negative control group [Poly (I:C)-MEM10] were saturated when an ELISA protocol, that includes pretreatment of the fish sera with 5% skim milk, was used. However, the saturated OD values in the negative control did not correlate with a specific immune response against VHSV, because the group showed low survival rate (only 10%) following the VHSV challenge. Also, OD values of Poly (I:C)- VHSV group were high, and the group showed high survival rate (97.5%) against VHSV challenge test. It was suggested that the high OD values were possibly due to the presence of anti-fetal bovine serum (FBS) cross-reactivity. To compensate this, we subtracted the absorbance of infectious hematopoietic necrosis (IHNV)-Ag plates from those of the VHSV-Ag plates. However, the average value for the Poly (I:C)-VHSV group (0.167) was lower than expected even though high survival rate. We used an advanced ELISA system to pre-treat fish sera with 5% skim milk and two novirhabdoviruses as capture antigens as well as 50% FBS. The corrected absorbance values for pre-treated fish sera from the negative control Poly (I:C)-MEM10 and experimental Poly (I:C)-VHSV groups averaged 0.033 and 0.579, respectively. The specific VHSV antibody response of the vaccinated group was assessed using fish sera pretreated with skim milk and FBS and by calculating the corrected absorbance values from ELISA with two novirhabdovirus capture antigens.

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