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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Microbiology and Biotechnology
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Journal DOI :
The Korean Society for Applied Microbiology and Biotechnology
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Volume & Issues
Volume 20, Issue 12 - Dec 2010
Volume 20, Issue 11 - Nov 2010
Volume 20, Issue 10 - Oct 2010
Volume 20, Issue 9 - Sep 2010
Volume 20, Issue 8 - Aug 2010
Volume 20, Issue 7 - Jul 2010
Volume 20, Issue 6 - Jun 2010
Volume 20, Issue 5 - May 2010
Volume 20, Issue 4 - Apr 2010
Volume 20, Issue 3 - Mar 2010
Volume 20, Issue 2 - Feb 2010
Volume 20, Issue 1 - Jan 2010
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Assessment of Root-Associated Paenibacillus polymyxa Groups on Growth Promotion and Induced Systemic Resistance in Pepper
Phi, Quyet-Tien ; Park, Yu-Mi ; Seul, Keyung-Jo ; Ryu, Choong-Min ; Park, Seung-Hwan ; Kim, Jong-Guk ; Ghim, Sa-Youl ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1605~1613
DOI : 10.4014/jmb.1007.07014
Twenty-nine P. polymyxa strains isolated from rhizospheres of various crops were clustered into five genotypic groups on the basis of BOX-PCR analysis. The characteristics of several plant growth-promoting factors among the isolates revealed the distinct attributes in each allocated group. Under gnotobiotic conditions, inoculation of pepper roots with P. polymyxa isolates significantly increased the biomass in 17 of total 29 treated plants with untreated plants. Experiments on induced systemic resistance (ISR) against bacterial spot pathogen Xanthomonas axonopodis pv. vesicatoria in pepper by P. polymyxa strains were conducted and only one isolate (KNUC265) was selected. Further studies into ISR mediation by the KNUC265 strain against the soft-rot pathogen Erwinia carotovora subsp. carotovora in tobacco demonstrated that the tobacco seedlings exposed to either bacterial volatiles or diffusible metabolites exhibited a reduction in disease severity. In conclusion, ISR and plant growth promotion triggered by P. polymyxa isolates were systemically investigated on pepper for the first time. The P. polymyxa KNUC265 strain, which elicited both ISR and plant growth promotion, could be potentially used in improving the yield of pepper and possibly of other crops.
Genetic and Phenotypic Diversity of Plant Growth Promoting Rhizobacteria Isolated from Sugarcane Plants Growing in Pakistan
Mehnaz, Samina ; Baig, Deeba N. ; Lazarovits, George ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1614~1623
DOI : 10.4014/jmb.1005.05014
Bacteria were isolated from roots of sugarcane varieties grown in the fields of Punjab. They were identified by using API20E/NE bacterial identification kits and from sequences of 16S rRNA and amplicons of the cpn60 gene. The majority of bacteria were found to belong to the genera of Enterobacter, Pseudomonas, and Klebsiella, but members of genera Azospirillum, Rhizobium, Rahnella, Delftia, Caulobacter, Pannonibacter, Xanthomonas, and Stenotrophomonas were also found. The community, however, was dominated by members of the Pseudomonadaceae and Enterobacteriaceae, as representatives of these genera were found in samples from every variety and location examined. All isolates were tested for the presence of five enzymes and seven factors known to be associated with plant growth promotion. Ten isolates showed lipase activity and eight were positive for protease activity. Cellulase, chitinase, and pectinase were not detected in any strain. Nine strains showed nitrogen fixing ability (acetylene reduction assay) and 26 were capable of solubilizing phosphate. In the presence of 100 mg/l tryptophan, all strains except one produced indole acetic acid in the growth medium. All isolates were positive for ACC deaminase activity. Six strains produced homoserine lactones and three produced HCN and hexamate type siderophores. One isolate was capable of inhibiting the growth of 24 pathogenic fungal strains of Colletotrichum, Fusarium, Pythium, and Rhizoctonia spp. In tests of their abilities to grow under a range of temperature, pH, and NaCl concentrations, all isolates grew well on plates with 3% NaCl and most of them grew well at 4 to
and at pH 11.
Repressed Quorum Sensing by Overexpressing LsrR Hampers Salmonella Evasion from Oxidative Killing Within Macrophages
Choi, Jeong-Joon ; Park, Joo-Won ; Ryu, Sang-Ryeol ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1624~1629
DOI : 10.4014/jmb.1008.08038
Bacterial cell-to-cell communication, termed quorum sensing (QS), leads to coordinated group behavior in a cell-density-dependent fashion and controls a variety of physiological processes including virulence gene expression. The repressor of the lsr operon, LsrR, is the only known regulator of LuxS/AI-2-mediated QS in Salmonella. Although lack of lsrR did not result in noticeable differences in Salmonella survival, the down-regulation of QS as a result of lsrR overexpression decreased Salmonella survival within macrophages. We found that impaired growth of Salmonella overexpressing lsrR within macrophages was due largely to its hypersensitivity to NADPH-dependent oxidative stress. This, in turn, was a result of decreased expression of genes involved in the oxidative stress response, such as sodA, sodCI, and sodCII, when lsrR was overexpressed. These results suggest that down-regulation of QS by excess LsrR can lower Salmonella virulence by hampering Salmonella evasion from oxidative killing within macrophages.
Response of Saccharomyces cerevisiae to Ethanol Stress Involves Actions of Protein Asr1p
Ding, Junmei ; Huang, Xiaowei ; Zhao, Na ; Gao, Feng ; Lu, Qian ; Zhang, Ke-Qin ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1630~1636
DOI : 10.4014/jmb.1007.07021
During the fermentation process of Saccharomyces cerevisiae, yeast cells must rapidly respond to a wide variety of external stresses in order to survive the constantly changing environment, including ethanol stress. The accumulation of ethanol can severely inhibit cell growth activity and productivity. Thus, the response to changing ethanol concentrations is one of the most important stress reactions in S. cerevisiae and worthy of thorough investigation. Therefore, this study examined the relationship between ethanol tolerance in S. cerevisiae and a unique protein called alcohol sensitive RING/PHD finger 1 protein (Asr1p). A real-time PCR showed that upon exposure to 8% ethanol, the expression of Asr1 was continuously enhanced, reaching a peak 2 h after stimulation. This result was confirmed by monitoring the fluorescence levels using a strain with a green fluorescent protein tagged to the C-terminal of Asr1p. The fluorescent microscopy also revealed a change in the subcellular localization before and after stimulation. Furthermore, the disruption of the Asr1 gene resulted in hypersensitivity on the medium containing ethanol, when compared with the wild-type strain. Thus, when taken together, the present results suggest that Asr1 is involved in the response to ethanol stress in the yeast S. cerevisiae.
Comparison of the Genomes of Deinococcal Species Using Oligonucleotide Microarrays
Jung, Sun-Wook ; Joe, Min-Ho ; Im, Seong-Hun ; Kim, Dong-Ho ; Lim, Sang-Yong ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1637~1646
DOI : 10.4014/jmb.1006.06001
The bacterium Deinococcus radiodurans is one of the most resistant organisms to ionizing radiation and other DNA-damaging agents. Although, at present, 30 Deinococcus species have been identified, the whole-genome sequences of most species remain unknown, with the exception of D. radiodurans (DRD), D. geothermalis, and D. deserti. In this study, comparative genomic hybridization (CGH) microarray analysis of three Deinococcus species, D. radiopugnans (DRP), D. proteolyticus (DPL), and D. radiophilus (DRPH), was performed using oligonucleotide arrays based on DRD. Approximately 28%, 14%, and 15% of 3,128 open reading frames (ORFs) of DRD were absent in the genomes of DRP, DPL, and DRPH, respectively. In addition, 162 DRD ORFs were absent in all three species. The absence of 17 randomly selected ORFs was confirmed by a Southern blot. Functional classification showed that the absent genes spanned a variety of functional categories: some genes involved in amino acid biosynthesis, cell envelope, cellular processes, central intermediary metabolism, and DNA metabolism were not present in any of the three deinococcal species tested. Finally, comparative genomic data showed that 120 genes were Deinococcus-specific, not the 230 reported previously. Specifically, ddrD, ddrO, and ddrH genes, previously identified as Deinococcus-specific, were not present in DRP, DPL, or DRPH, suggesting that only a portion of ddr genes are shared by all members of the genus Deinococcus.
Purification and Characterization of a Ubiquitin-like System for Autophagosome Formation
Bae, Ju-Young ; Park, Hyun-Ho ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1647~1652
DOI : 10.4014/jmb.1007.07061
Autophagy refers to the bulk degradation of cellular proteins and organelles through an autophagosome and plays a pivotal role in the development, cellular differentiation, aging, and elimination of aberrant structures. A failure of autophagy has been implicated in a growing list of mammalian disease states, including cancer and cardiomyopathy. Two ubiquitin-like systems are highly involved in autophagy, especially in the formation of autophagosomes. Here, we purified and characterized Atg7 (an E1-like enzyme), and Atg3 and Atg10 (E2-like enzymes) in order to gain an insight into the role played by ubiquitin-like systems in the formation of autophagosomes. Interestingly, we observed that Atg7 forms a homodimer to construct an active conformation, unlike other E1-like enzymes. Although Atg3 was detected as a monomer under physiological conditions, Atg10 existed in an oligomeric form, indicating that the mechanism by which Atg10 functions may differ from that of Atg3.
Cloning and Expression of a Thermostable
-Galactosidase from the Thermophilic Fungus Talaromyces emersonii in the Methylotrophic Yeast Pichia pastoris
Simila, Janika ; Gernig, Anita ; Murray, Patrick ; Fernandes, Sara ; Tuohy, Maria G. ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1653~1663
DOI : 10.4014/jmb.1005.05043
The first gene (
-gal1) encoding an extracellular
-Dgalactosidase from the thermophilic fungus Talaromyces emersonii was cloned and characterized. The
-gal1 gene consisted of an open reading frame of 1,792 base pairs interrupted by six introns that encoded a mature protein of 452 amino acids, including a 24 amino acid secretory signal sequence. The translated protein had highest identity with other fungal
-galactosidases belonging to glycosyl hydrolase family 27. The
-gal1 gene was overexpressed as a secretory protein with an N-terminal histidine tag in the methylotrophic yeast Pichia pastoris. Recombinant
-Gal1 was secreted into the culture medium as a monomeric glycoprotein with a maximal yield of 10.75 mg/l and purified to homogeneity using Hisbinding nickel-agarose affinity chromatography. The purified enzyme was maximally active at
, pH 4.5, and lost no activity over 10 days at
-Gal1 followed Michaelis-Menten kinetics (
) and was inhibited competitively by galactose (
of 0.57 mM,
of 2.77 mM). The recombinant T. emersonii
-galactosidase displayed broad substrate preference, being active on both oligo- and polymeric substrates, yet had strict specificity for the
-galactosidic linkage. Owing to its substrate preference and noteworthy stability,
-Gal1 is of particular interest for possible biotechnological applications involving the processing of plant materials.
Bioproduction and Anticancer Activity of Biosurfactant Produced by the Dematiaceous Fungus Exophiala dermatitidis SK80
Chiewpattanakul, Paramaporn ; Phonnok, Sirinet ; Durand, Alain ; Marie, Emmanuelle ; Thanomsub, Benjamas Wongsatayanon ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1664~1671
DOI : 10.4014/jmb.1007.07052
A new biosurfactant producer was isolated from palm-oil-contaminated soil and later identified through morphology and DNA sequencing as the yeast-like fungus Exophiala dermatitidis. Biosurfactant production was catalyzed by vegetable oil, supplemented with a basal medium. The culture conditions that provided the biosurfactant with the highest surface activity were found to be 5% palm oil with 0.08%
, at a pH of 5.3, with shaking at 200 rpm, and a temperature of
for a 14-day period of incubation. The biosurfactant was purified, in accordance with surfactant properties, by solvent fractionation using silica gel column chromatography. The chemical structure of the strongest surface-active compound was elucidated through the use of NMR and mass spectroscopy, and noted to be monoolein, which then went on to demonstrate antiproliferative activity against cervical cancer (HeLa) and leukemia (U937) cell lines in a dose-dependent manner. Interestingly, no cytotoxicity was observed with normal cells even when high concentrations were used. Cell and DNA morphological changes, in both cancer cell lines, were observed to be cell shrinkage, membrane blebbling, and DNA fragmentation.
Identification of Streptomyces sp. KH29, Which Produces an Antibiotic Substance Processing an Inhibitory Activity Against Multidrug-Resistant Acinetobacter baumannii
Lee, Keyong-Ho ; Kim, Gye-Woong ; Rhee, Ki-Hyeong ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1672~1676
DOI : 10.4014/jmb.1007.07035
The Actinomycete strain KH29 is antagonistic to the multidrug-resistant Acinetobacter baumannii. Based on the diaminopimelic acid (DAP) type, and the morphological and physiological characteristics observed through the use of scanning electron microscopy (SEM), KH29 was confirmed as belonging to the genus Streptomyces. By way of its noted 16S rDNA nucleotide sequences, KH29 was found to have a relationship with Streptomyces cinnamonensis. The production of an antibiotic from this strain was found to be most favorable when cultured with glucose, polypeptone, and yeast extract (PY) medium for 6 days at
. The antibiotic produced was identified, through comparisons with reported spectral data including MS and NMR as a cyclo(L-tryptophanyl-L-tryptophanyl). Cyclo(L-Trp-L-Trp), from the PY cultures of KH29, was seen to be highly effective against 41 of 49 multidrug-resistant Acinetobacter baumannii. Furthermore, cyclo(L-Trp-L-Trp) had antimicrobial activity against Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Saccharomyces cerevisiae, Aspergillus niger, and Candida albicans, However, it was ineffective against Streptomyces murinus.
The Effect of Protectants and pH Changes on the Cellular Growth and Succinic Acid Yield of Mannheimia succiniciproducens LPK7
Oh, Young-Hoon ; Oh, In-Jae ; Jung, Chang-Kyou ; Lee, Sang-Yup ; Lee, Jin-Won ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1677~1680
DOI : 10.4014/jmb.1003.03032
The harmful effects of succinic acid and oxidative stress on cell growth were determined during batch fermentation with Mannheimia succiniciproducens LPK7, a powerful succinic acid-producing strain, and conditions were optimized to minimize these effects. In terms of toxicity, the cell concentration decreased as the concentration of succinic acid increased. By changing the pH from 6.5 to 7 during fermentation, the cell concentration increased by about 10%, and the level of succinic acid production was 6% higher than that of the control. In addition, by introducing protectants, the cell concentration increased by about 10%, and the level of succinic acid produced was increased by 3%.
Purification and Characterization of a Thermostable Cellobiohydrolase from Fomitopsis pinicola
Shin, Keum ; Kim, Yoon-Hee ; Jeya, Marimuthu ; Lee, Jung-Kul ; Kim, Yeong-Suk ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1681~1688
DOI : 10.4014/jmb.1008.08009
A screening for cellobiohydrolase (CBH) activity was performed and Fomitopsis pinicola KMJ812 was selected for further characterization as it produced a high level of CBH activity. An extracellular CBH was purified to homogeneity by sequential chromatography of F. pinicola culture supernatants. The molecular mass of the F. pinicola CBH was determined to be 64 kDa by SDS-PAGE and by size-exclusion chromatography, indicating that the enzyme is a monomer. The F. pinicola CBH showed a
value of 42 h at
and catalytic efficiency of
-D-cellobioside, one of the highest levels seen for CBH-producing microorganisms. Its internal amino acid sequences showed a significant homology with hydrolases from glycoside hydrolase family 7. Although CBHs have been purified and characterized from other sources, the F. pinicola CBH is distinguished from other CBHs by its high catalytic efficiency and thermostability.
Identification and Characterization of a Pantothenate Kinase (PanK-sp) from Streptomyces peucetius ATCC 27952
Mandakh, Ariungerel ; Niraula, Narayan Prasad ; Kim, Eung-Pil ; Sohng, Jae-Kyung ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1689~1695
DOI : 10.4014/jmb.1007.07058
Pantothenate kinase (PanK) catalyzes the first step in the biosynthesis of the essential and ubiquitous cofactor coenzyme A (CoA) in all organisms. Here, we report the identification, cloning, and characterization of panK-sp from Streptomyces peucetius ATCC 27952. The gene encoded a protein of 332 amino acids with a calculated molecular mass of 36.8 kDa and high homology with PanK from S. avermitilis and S. coelicolor A3(2). To elucidate the putative function of PanK-sp, it was cloned into pET32a(+) to construct pPKSP32, and the PanK-sp was then expressed in E. coli BL21(DE3) as a His-tag fusion protein and purified by immobilized metal affinity chromatography. The enzyme assay of PanK-sp was carried out as a coupling assay. The gradual decrease in NADH concentration with time clearly indicated the phosphorylating activity of PanK-sp. Furthermore, the ca. 1.4-fold increase of DXR and the ca. 1.5-fold increase of actinorhodin by in vivo overexpression of panK-sp, constructed in pIBR25 under the control of a strong
promoter, established its positive role in secondary metabolite production from S. peucetius and S. coelicolor, respectively.
Repeated Random Mutagenesis of
-Amylase from Bacillus licheniformis for Improved pH Performance
Priyadharshini, Ramachandran ; Manoharan, Shankar ; Hemalatha, Devaraj ; Gunasekaran, Paramasamy ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1696~1701
DOI : 10.4014/jmb.1008.08013
-amylases activity was improved by random mutagenesis and screening. A region comprising residues from the position 34-281 was randomly mutated in B. licheniformis
-amylase (AmyL), and the library with mutations ranging from low, medium, and high frequencies was generated. The library was screened using an effective liquid-phase screening method to isolate mutants with an altered pH profile. The sequencing of improved variants indicated 2-5 amino acid changes. Among them, mutant TP8H5 showed an altered pH profile as compared with that of wild type. The sequencing of variant TP8H5 indicated 2 amino acid changes, Ile157Ser and Trp193Arg, which were located in the solvent accessible flexible loop region in domain B.
Characterization of Yakju Brewed from Glutinous Rice and Wild-Type Yeast Strains Isolated from Nuruks
Kim, Hye-Ryun ; Kim, Jae-Ho ; Bae, Dong-Hoon ; Ahn, Byung-Hak ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1702~1710
DOI : 10.4014/jmb.1011.11004
Korean traditional rice wines yakju and takju are generally brewed with nuruk as the source of the saccharogenic enzymes by natural fermentation. To improve the quality of Korean rice wine, the microorganisms in the nuruk need to be studied. The objective of this research was to improve the quality of Korean wine with the wild-type yeast strains isolated from the fermentation starter, nuruk. Only strain YA-6 showed high activity in 20% ethanol. Precipitation of Y89-5-3 was similar to that of very flocculent yeast (>80%) at 75.95%. Using 18S rRNA sequencing, all 10 strains were identified as Saccharomyces cerevisiae. Volatile compounds present in yakju were analyzed by gas chromatography-mass selective detector. The principal component analysis (PCA) of the volatile compounds grouped long-chain esters on the right side of the first principal component, PC1; these compounds were found in yakju that was made with strains YA-6, Y89-5-3, Y89-5-2, Y90-9, and Y89-1-1. On the other side of PC1 were short-chain esters; these compounds were found in wines that were brewed with strains Y183-2, Y268-3, Y54-3, Y98-4, and Y88-4. Overall, the results indicated that using different wild-type yeast strains in the fermentation process significantly affects the chemical characteristics of the glutinous rice wine.
Characterization of a Paenibacillus woosongensis
-Arabinofuranosidase Produced by Recombinant Escherichia coli
Kim, Yeon-A ; Yoon, Ki-Hong ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1711~1716
DOI : 10.4014/jmb.1010.10040
A gene encoding the
-arabinofuranosidase (XylC) of Paenibacillus woosongensis was cloned into Escherichia coli. This xylC gene consisted of 1,425 nucleotides, encoding a polypeptide of 474 amino acid residues. The deduced amino acid sequence exhibited an 80% similarity with those of both Clostridium stercorarium
-N-arabinosidase and Bacillus cellulosilyticus
-arabinofuranosidase, belonging to the glycosyl hydrolase family 43. The structural gene was subcloned with a C-terminal His-tag into a pET23a(+) expression vector. The His-tagged XylC, purified from a cell-free extract of a recombinant E. coli BL21(DE3) Codon Plus carrying a xylC gene by affinity chromatography, was active on para-nitrophenyl-
-arabinofuranoside (pNPA) as well as para-nitrophenyl-
-xylopyranoside (pNPX). However, the enzymatic activities for the substrates were somewhat incongruously influenced by reaction pHs and temperatures. The enzyme was also affected by various chemicals at different levels. SDS (5 mM) inhibited the enzymatic activity for pNPX, while enhancing the enzymatic activity for pNPA. Enzyme activity was also found to be inhibited by addition of pentose or hexose. The Michaelis constant and maximum velocity of the purified enzyme were determined for hydrolysis of pNPX and pNPA, respectively.
Bacterial Community Composition and Diversity of a Full-Scale Integrated Fixed-Film Activated Sludge System as Investigated by Pyrosequencing
Kwon, Soon-Dong ; Kim, Taek-Seung ; Yu, Gi-Hyeon ; Jung, Joon-Hong ; Park, Hee-Deung ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1717~1723
DOI : 10.4014/jmb.1007.07012
The integrated fixed-film activated sludge (IFAS) system is a variation of the activated sludge wastewater treatment process, in which hybrid suspended and attached biomass is used to treat wastewater. Although the function and performance of the IFAS system are well studied, little is known about its microbial community structure. In this study, the composition and diversity of the bacterial community of suspended and attached biomass samples were investigated in a full-scale IFAS system using a high-throughput pyrosequencing technology. Distinct bacterial community compositions were examined for each sample and appeared to be important for its features different from conventional activated sludge processes. The abundant bacterial groups were Betaproteobacteria (59.3%), Gammaproteobacteria (8.1%), Bacteroidetes (5.2%), Alphaproteobacteria (3.9%), and Actinobacteria (3.2%) in the suspended sample, whereas Actinobacteria (14.6%), Firmicutes (13.6%), Bacteroidetes (11.6%), Betaproteobacteria (9.9%), Gammaproteobacteria (9.25%), and Alphaproteobacteria (7.4%) were major bacterial groups in the attached sample. Regarding the diversity, totals of 3,034 and 1,451 operational taxonomic units were identified at the 3% cutoff for the suspended and attached samples, respectively. Rank abundance and community analyses demonstrated that most of the diversity was originated from rare species in the samples. Taken together, the information obtained in this study will be a base for further studies relating to the microbial community structure and function of the IFAS system.
Cold-Adapted and Rhizosphere-Competent Strain of Rahnella sp. with Broad-Spectrum Plant Growth-Promotion Potential
Vyas, Pratibha ; Joshi, Robin ; Sharma, K.C. ; Rahi, Praveen ; Gulati, Ashu ; Gulati, Arvind ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1724~1734
DOI : 10.4014/jmb.1007.07030
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.
Mutations in the gyrB, parC, and parE Genes of Quinolone-Resistant Isolates and Mutants of Edwardsiella tarda
Kim, Myoung-Sug ; Jun, Lyu-Jin ; Shin, Soon-Bum ; Park, Myoung-Ae ; Jung, Sung-Hee ; Kim, Kwang-Il ; Moon, Kyung-Ho ; Jeong, Hyun-Do ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1735~1743
DOI : 10.4014/jmb.1009.09008
The full-length genes gyrB (2,415 bp), parC (2,277 bp), and parE (1,896 bp) in Edwardsiella tarda were cloned by PCR with degenerate primers based on the sequence of the respective quinolone resistance-determining region (QRDR), followed by elongation of 5' and 3' ends using cassette ligation-mediated PCR (CLMP). Analysis of the cloned genes revealed open reading frames (ORFs) encoding proteins of 804 (GyrB), 758 (ParC), and 631 (ParE) amino acids with conserved gyrase/topoisomerase features and motifs important for enzymatic function. The ORFs were preceded by putative promoters, ribosome binding sites, and inverted repeats with the potential to form cruciform structures for binding of DNA-binding proteins. When comparing the deduced amino acid sequences of E. tarda GyrB, ParC, and ParE with those of the corresponding proteins in other bacteria, they were found to be most closely related to Escherichia coli GyrB (87.6% identity), Klebsiella pneumoniae ParC (78.8% identity), and Salmonella Typhimurium ParE (89.5% identity), respectively. The two topoisomerase genes, parC and parE, were found to be contiguous on the E. tarda chromosome. All 18 quinolone-resistant isolates obtained from Korea thus far did not contain subunit alternations apart from a substitution in GyrA (Ser83
Arg). However, an alteration in the QRDR of ParC (Ser84
Ile) following an amino acid substitution in GyrA (Asp87
Gly) was detected in E. tarda mutants selected in vitro at
ciprofloxacin (CIP). A mutant with a GyrB (Ser464
Leu) and GyrA (Asp87
Gly) substitution did not show a significant increase in the minimum inhibitory concentration (MIC) of CIP. None of the in vitro mutants exhibited mutations in parE. Thus, gyrA and parC should be considered to be the primary and secondary targets, respectively, of quinolones in E. tarda.
Gibberellin-Producing Endophytic Fungi Isolated from Monochoria vaginalis
Ahmad, Nadeem ; Hamayun, Muhammad ; Khan, Sumera Afzal ; Khan, Abdul Latif ; Lee, In-Jung ; Shin, Dong-Hyun ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1744~1749
DOI : 10.4014/jmb.1005.05018
The role of endophytic fungi in plant growth and development is well documented. However, endophytic fungi with growth promotion capacity have never been isolated from weeds previously. In the current study, we isolated 8 fungal endophytes from the roots of Monochoria vaginalis, a serious weed of rice paddy in Korea. These isolates were screened on Waito-C, in order to identify plant growth promoting metabolites. Two fungal isolates (M5.A & M1.5) significantly promoted the plant height and shoot length of Waito-C during preliminary screening experiments. The culture filtrates (CFs) of M5.A and M1.5 also promoted the shoot length of Echinocloa crusgalli. Gibberellins (GAs) analysis of the CFs of M5.A and M1.5 showed that these endophytic fungi secrete higher quantities of GAs as compared with wild-type G. fujikuroi KCCM12329. The CF of M5.A contained bioactive GAs (
, 2.8 ng/ml;
, 2.6 ng/ml, and
, 6.68 ng/ml) in conjunction with physiologically inactive
(1.61 ng/ml) and
(0.18 ng/ml). The CF of M1.5 contained physiologically active GAs (
, 1.64 ng/ml;
, 1.37 ng/ml and
, 6.29 ng/ml) in conjunction with physiologically inactive
(0.3 ng/ml), and
(0.59 ng/ml). M5.A and M1.5 were identified as new strains of Penicillium sp. and Aspergillus sp., respectively, based on their 18S rDNA sequence homology and phylogenetic analysis.
A Genetic Comparison of Brucella abortus Isolates from Animals and Humans by Using the MLVA Assay
Her, Moon ; Kang, Sung-Il ; Kim, Jong-Wan ; Kim, Ji-Yeon ; Hwang, In-Yeong ; Jung, Suk-Chan ; Park, Sang-Hee ; Park, Mi-Yeoun ; Yoo, Han-Sang ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1750~1755
DOI : 10.4014/jmb.1005.05039
The MLVA assay is known to have a high ability to identify and discriminate Brucella species, so that it can be used as an epidemiological tool to discriminate Brucella isolates originating from restricted geographic sources. In this study, the genetic profiles of 38 B. abortus isolates from humans were analyzed and compared with genotypes from animal isolates in South Korea. As a result, it was found that they did not show high genetic diversity and were compacted. They were clustered together with animal isolates, showing a significant correlation to regional distributions. With its ability to prove a significant genetic correlation among B. abortus isolates from animals and humans in South Korea, the MLVA assay could be utilized as part of a program to control and eradicate brucellosis, one of the major zoonoses. This study represents the first data of genetic correlation of B. abortus isolates from humans and animals in South Korea.
Antigenicity of Partial Fragments of Recombinant Pasteurella multocida Toxin
Lee, Jeong-Min ; Woo, Hee-Jong ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1756~1763
DOI : 10.4014/jmb.1004.04036
Pasteurella multocida serogroup D strain, which produces P. multocida toxin (PMT), is a widespread and harmful pathogen of respiratory diseases such as pneumonia and progressive atrophic rhinitis (PAR) in swine. Vaccination has been considered the most desirable and effective approach for controlling the diseases caused by toxigenic P. multocida. To investigate the antigenicity and immunogenicity of partial fragments of recombinant PMT, recombinant proteins of the N-terminal (PMT-A), middle (PMT-B), C-terminal (PMT-C), and middle-C-terminal (PMT2.3) regions of PMT were successfully produced in an Escherichia coli expression system. The molecular masses of PMT-A, PMT-B, PMT-C, and PMT2.3 were ca. 53, 55, 35, and 84 kDa, respectively, purified by nickel-nitrilotriacetic acid (Ni-NTA) affinity column chromatography. All the recombinant proteins except for PMT-A showed immune responses to antisera obtained from a swine showing symptoms of PAR. Moreover, high titers of PMT-specific antibodies were raised from mice immunized with each of the recombinant proteins; however, the immunoreactivities of the antibodies to authentic PMT and heat-inactivated whole bacteria were different, respectively. In the protection study, the highest protection against homologous challenge was shown in the case of PMT2.3; relatively poor protections occurred for the other PMT fragments.
Antibiotic Resistance Profiles of Staphylococcus pseudintermedius Isolates from Canine Patients in Korea
Yoon, Jang-Won ; Lee, Ki-Jong ; Lee, So-Young ; Chae, Min-Joo ; Park, Jae-Keun ; Yoo, Jong-Hyun ; Park, Hee-Myung ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1764~1768
DOI : 10.4014/jmb.1001.01011
In this study, the prevalence of antibiotic resistance was examined among 74 Staphylococcus pseudintermedius strains recently isolated from clinical cases of canine pyoderma and otitis externa at the veterinary teaching hospital at Konkuk University, Korea. Bacterial resistance to the nine commonly used antibiotics was evaluated by a standard disk diffusion technique based on the guidelines of the Clinical and Laboratory Standards Institute. The results demonstrated that most S. pseudintermedius isolates were resistant to penicillin (95.9%) or tetracycline (91.9%), but highly susceptible to amoxicillin/clavulanic acid (90.5%). Among the 74 isolates, 13 mecA-positive and methicillin-resistant S. pseudintermedius (MRSP) strains were identified, displaying a high level of resistance (84.6-100%) to each of the individual antibiotics evaluated, with the exception of amoxicillin/clavulanic acid (46.2% resistance). Notably, all of the MRSP isolates exhibited simultaneous resistance to four or more different antibiotics, indicating that they are multiple drug resistant (MDR) strains. Taken together, these results imply that more careful selection or prescription of antibiotics for canine pyoderma and otitis externa should be required for reducing the emergence and/or spread of MDR strains, especially MDR-MRSP isolates, in veterinary pet clinics in Korea.
Selection of Peptides Binding to HCV E2 and Inhibiting Viral Infectivity
Hong, Hye-Won ; Lee, Seong-Wook ; Myung, Hee-Joon ;
Journal of Microbiology and Biotechnology, volume 20, issue 12, 2010, Pages 1769~1771
DOI : 10.4014/jmb.1007.07036
The envelope glycoprotein E2 of hepatitis C virus (HCV) binds to various cell surface receptors for viral infection. We performed biopanning against this protein and selected peptides from phage display peptide libraries. Two short peptides, pep7-1 and pep12-1, were selected and their ability to inhibit the infection process was investigated. When pep7-1 was present, the infectivity of HCV particles in cell culture was notably decreased. This decrease was demonstrated by Western blot analysis, immunofluorescence assay, and reverse transcription PCR assay. However, pep12-1 showed little inhibitory effect on HCV infection.