Journal of Microbiology

Microbial Metal Transformations: Geoffrey M. Gadd; J. Microbiol. 2001;39(2):83-88.

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Abstract: There is considerable interest in how microbiological processes can affect the behaviour of metal contaminants in natural and engineered environments and their potential for bioremediation. The extent to which microorganisms can affect metal contaminants is dependent on the identity and chemical form of the metal and the physical and chemical nature of the contaminated site or substance. In general terms, microbial processes which solubilize metals increase their bioavailability and potential toxicity, whereas those that immobilize them reduce bioavailability. The balance between mobilization and immobilization varies depending on the metal, the organisms, their environment and physico-chemical conditions.

Acid Stress Responses of Salmonella and E. coli : Survival Mechanisms, Regulation, and Implications for Pathogenesis: John W. Foster; J. Microbiol. 2001;39(2):89-94.

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Abstract: review

Controlled Expression and Secretion of Aspergillus oryzae Alkaline Protease in Aspergillus nidulans: Eun Ah Kim , Jeong Goo Lee , Mi Kyung Whang , Hee Moon Park , Jeong Yoon Kim , Suhn Kee Chae , Pil Jae Maeng; J. Microbiol. 2001;39(2):95-101.

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Abstract: In an effort to develop an efficient expression and secretion system for heterologous proteins in Aspergillus nidulans, the PCR-amplified coding sequence for alkaline protease (AlpA) of A. oryzae was cloned into a fungal expression vector downstream of A. nidulans alcA (alcohol dehydrogenase) promoter to yield pRAAlp. Transformation of A. nidulans with pRAAlp gave stable transformants harboring various copy numbers (3 to 10) of integrated alpA gene, from among which 6 representatives were selected. On a medium containing 0.8% ammonium sulfate that represses the expression of the hosts own protease, the alcA promoter-controlled AlpA expression was strongly induced by threonine but repressed by glucose. The level of AlpA secretion was highest (approximately 666 mU/ml) in transformant ALP6 containing the largest copy number integrated alpA. However, the level of AlpA secretion was not necessarily proportional to the copy numbers of the integrated alpA genes. The N-terminal sequence of the secreted mature AlpA was determined to be Gly-Leu-Thr-Thr-Gln-Lys-Ser and its molecular mass to be approximately 34 kDa, indicating that AlpA is properly processed by the removal of 121 N-terminal amino acids.

A Novel UV-Sensitivity Mutation Induces Nucleotide Excision Repair Phenotype and Shows Epistatic Relationships with UvsF and UvsB Groups in Aspergillus nidulans: F. Baptista , M. A. A. Castro-Prado; J. Microbiol. 2001;39(2):102-108.

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Abstract: DNA damage response has a central role in the maintenance of genomic integrity while mutations in related genes may result in a range of disorders, including neoplasic formations. The uvsZ1 characterized in this report is a novel uvs mutation in Aspergillus nidulans, resulting in a nucleotide excision repair (NER) phenotype: UV-sensitivity before DNA synthesis (quiescent cells), high UV-induced mutation frequency and probable absence of involvement with mitotic and meiotic recombinations. The mutation is recessive and non-allelic to the previously characterized uvsA101 mutation, also located on the paba-y interval on chromosome I. uvsZ1 showed wild-type sensitivity to MMS, which suggests non-involvement of this mutation with BER. Epitasis tests showed that the uvsZ gene product is probably involved in the same repair pathways as UVSB or UVSH proteins. Although mutations in these proteins result in an NER phenotype, UVSB is related with cell cycle control and UVSH is associated with the post-replicational repair pathway. The epistatic interaction among uvsZ1 and uvsB413 and uvsH77 mutations indicates that different repair systems may be related with the common steps of DNA damage response in Aspergillus nidulans.

Cloning and Sequencing Analysis of cadC Encoding Transcriptional Activator CadC from Salmonella typhimurium: Bae Hoon Kim , Ho Jeong Lee , In Soo Lee , Sung Ho Bang; J. Microbiol. 2001;39(2):109-115.

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Abstract: Salmonella typhimurium possesses a cad operon, which contributes to an adaptive response against an acidifying environment. In Escherichia coli, the activation of the cad operon is dependent on cadC, which is located upstream of the operon. However, the activator of cad operon in S. typhimurium has not been known until now. In this study, we selected a putative cadC mutant by trasposon mutagenesis and cloned the cadC of S. typhimurium. Moreover, the cadC mutant was complemented by cadC clone. The cadC gene from S. typhimurium LT-2 consists of 1539 bp encoding a polypeptide ob 512 amino acids, and shows sequence similarity to cadC of E. coli with 53% identity and 67% similarity. The hydrophobicity profile of the S. typhimurim CadC sequence is very similar to E. coli CadC.

Prevalence and Antibiotic Susceptibility of Vancomycin-Resistant Enterococci in Chicken Intestines and Fecal Samples from Healthy Young Children and Intensive Care Unit Patients: Shin Moo Kim , Eun Sook Shim , Chi Nam Seong; J. Microbiol. 2001;39(2):116-120.

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Abstract: The prevalence, resistance genotype and antibiotic susceptibility of vancomycin-resistant enterococci (VRE) were determined. Prevalence of VRE in chickens, healthy children and intensive care unit (ICU) patients was 43.0%, 12.7% and 24.1%, respectively. Forty out of 56 isolates from chicken intestines were identified as Enterococcus faecium, and 12 were E. faecalis. All the isolates contained the vanA gene. Nine out of 13 VRE isolates from patients and two out of 21 from healthy young children were identified as E. faecium. The resistance types of E. faecium, E. gallinarium and E. casseliflavus were VanA, VanC1, and VanC2, respectively. The mimimum inhibitory concentrations (MICs) of E. faecium, E. gallinarium, and E. casseliflavus to vancomycin were 512, 8 and 4 g/ml, respectively. Specifically, E. faecium isolates were resistant to most of antibiotics except ampicillin and gentamicin. This is the first report of high VanA type VRE prevalence in nonhospitalized young children in Korea.

Anti-tumor Activity of the Fruitbody Extract of Basidiomycete, Phellinus linteus: Jong-Soon Lim , Seung-Hyung Kim , Jin-Seo Park , Jeong-Youl Choi , Seong Joo Park , Kwang-Soo Shin; J. Microbiol. 2001;39(2):121-125.

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Abstract: Methanol extract prepared from the fruitbody of Phellinus linteus (EPL) showed anti-tumor and immuno-stimulating activities. The invasion activity of B16-F10 melanoma cells through a reconstituted basement membrane to the collagen-coated lower surface of the filters was inhibited about 67% by EPL (100 ug/ml). Also, EPL inhibited the expression of the mRNA for MMP-2 and MMP-9. In vivo treatment of C57BL/6 mice (150 mg/kg) with EPL for 14 days, the pulmonary colonization was found to be inhibited about 75%. Using reverse transcriptionpolymerase chain reaction (RT-PCR) analysis, we found that cytokine IL-12 and INF-[gamma] genes were induced by EPL. Furthermore, EPL stimulated the proliferation of CD4^+ (33.5%) and CD8^+ (17.7%) in mouse splenocytes.

Selection of RAPD Markers for Phytophthora infestans and PCR Detection of Phytophthora infestans from Potatoes: Kyoung Su Kim , Youn Su Lee; J. Microbiol. 2001;39(2):126-132.

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Abstract: For rapid and secure differentiation of P. infestans from other Phytophthora species, two fragments obtained from randomly amplified polymorphic DNA (RAPD) profiles were selected as markers. Also, primers for in polymerase chain reaction (PCR) to detect P. infestans specifically were developed by analyzing the sequences of ITSII regions in rDNA of Phytophthora species. The primers, PISP-1 and ITS3 amplified a single. Fragment 450 bp of about in P. infestans , but not in other fungal or bacterial isolates. Annealing temperatures and template DNA quantities were varied for the optimization of PCR conditions. From the result of the PCR detection study, species-specific primers were selected under annealing temperatures ranging from 55 C to 61 C, and template DNA levels ranging from 10 pg to 100 ng.

Antagonism of Bacterial Extracellular Metabolites to Freshwater-Fouling Invertebrate Zebra Mussels, Dreissena polymorpha: Ji-Dong Gu , Ralph Mitchell; J. Microbiol. 2001;39(2):133-138.

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Abstract: We investigated the antagonism of indigenous bacteria isolated from stressed mussels and their extra-cellular metabolites on the adult zebra mussel, Dreissena polymorpha. Selective bacterial isolates including Aeromonas media, A. salmonicida, A. veronii, and Shewanella putrefaciens, showed strong lethality against adult mussels and 100% mortality was observed within 5 days of incubation. Bacterial metabolites, fractionated and concentrated from stationary-phase culture supernatants of these bacterial isolates, displayed varying degrees of antagonistic effects on zebra mussels. Among the three size fractions examined, <5, 5-10, and >10 kDa, the most lethal fraction seems to be >10 kDa for three of the four isolates tested. Further chemical analyses of these size fractions revealed that the predominant constituents were polysaccharides and proteins. No 2-keto-3-deoxyoctanoic acid (2-KDO), deoxyri-bonucleic acids (DNA) or uronic acid were detectable. Extraction of supernatants of two antagonistic isolates with polar solvent suggested that polar molecules are present in the active fraction. Our data suggest that extracellular metabolites produced by antagonistic bacteria are also involved in disease development in zebra mussels and elucidation of the mechanisms involved may offer a novel strategy for control of biofouling invertebrates.

Isolation of a Medium Chain Length Polyhydroxyalkanoic Acids Degrading Bacterium, Janthinobacterium lividum: Jin-Seo Park , Jeong-Youl Choi , Pil-Mun Joung , Seong Joo Park , Young Ha Rhe e , Kwang-Soo Shin; J. Microbiol. 2001;39(2):139-141.

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Abstract: Medium-chain length polyhydroxyalkanoic acids (MCL-PHAs) degrading bacterium was isolated from the soil. The bacterium was identified as Janthinobacterium lividum by its biochemical properties, cell membrane fatty acids composition, and 16S rDNA sequence analysis. The bacterium showed a similarity of 0.911 with J. lividum according to the cell membrane fatty acids analysis and a similarity of 97% in the 16S rDNA sequence analysis. Culture supernatant of the bacterium showed the highest depolymerase activity toward polyhydroxynonanoic acid (PHN) that did not degrade the poly-[beta]-hydroxybutyric acid (PHB). The esterase activity was also detected with p-nitrophenyl (PNP) esters of fatty acids such as PNP-octanoic acid, PNP-dodecanoic acid, PNP-decanoic acid, and PNP-hexanoic acid.

Alterations in the Activities of Antioxidant Enzymes of Human Dermal Microvascular Endothelial Cells Infected with Orientia tsutsugamushi: Young-Sang Koh; J. Microbiol. 2001;39(2):142-145.

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Abstract: Changes in the activities of several antioxidant enzymes in transformed human dermal microvascular endothelial cells (HMEC-1) by infection with the obligate intracellular bacterium Orientia tsutsugamushi, the causative agent of scrub typhus, were investigated. The activities of glucose-6-phosphate dehydrogenase, catalase, and glutathione peroxidase were significantly decreased in HMEC-1 cells infected with O. tsutsugamushi. However, the level of superoxide dismutase increased slightly. Furthermore, increased levels of intracellular peroxide was observed in HMEC-1 during infection. These results support the hypothesis that cells infected by this intracellular bacterium experience oxidant-mediated injury that may eventually contribute to cell death.

Antibacterial Activities of Lactobacillus crispatus ATCC 33820 and Lactobacillus gasseri ATCC 33323: Jin-Woo Kim , S.N. Rajagopal; J. Microbiol. 2001;39(2):146-148.

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Abstract: Lactobacillus crispatus ATCC 33820 and L. gasseri ATCC 33323 were grown in MRS broth (pH 6.5) at 37 C for 24 h and the antibacterial activities of cell free culture supernatants were determined by the agar well diffusion method. The culture supernatants were inhibitory to Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis, Pediococcus acidilacticii, and Lactobacillus helveticus. The supernatants did not show any lysozyme activity. Addition of catalase did not affect the antibacterial activities of the supernatants. The antibacterial substances were heat stable (100 C for 60 min) and sensitive to proteases.

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