• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.511-520
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• 2016

The most energy-demanding step of wastewater treatment is the aeration-dependent elimination of organic carbon. Microbial fuel cells (MFCs) offer an alternative strategy in which carbon elimination is conducted by anaerobic microorganisms that transport respiratory electrons originating from carbon oxidation to an anode. Hence, chemical energy is directly transformed into electrical energy. In this study, the use and stability of barcode-containing exoelectrogenic model biofilms under non-axenic wastewater treatment conditions are described. Genomic barcodes were integrated in Shewanella oneidensis, Geobacter sulfurreducens, and G. metallireducens. These barcodes are unique for each strain and allow distinction between those cells and naturally occurring wild types as well as quantification of the amount of cells in a biofilm via multiplex qPCR. MFCs were pre-incubated with these three strains, and after 6 days the anodes were transferred into MFCs containing synthetic wastewater with 1% wastewater sludge. Over time, the system stabilized and the coulomb efficiency was constant. Overall, the initial synthetic biofilm community represented half of the anodic population at the end of the experimental timeline. The part of the community that contained a barcode was dominated by G. sulfurreducens cells (61.5%), while S. oneidensis and G. metallireducens cells comprised 10.5% and 17.9%, respectively. To the best of our knowledge, this is the first study to describe the stability of a synthetic exoelectrogenic consortium under non-axenic conditions. The observed stability offers new possibilities for the application of synthetic biofilms and synthetically engineered organisms fed with non-sterile waste streams.

• Journal of Life Science
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• v.12 no.2
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• pp.158-163
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• 2002

For axenic isolation of the cyanobacterium Microcystis aeruginosa, water bloom at the Mulgum station from the Nakdong River was pretreated by shaking with distilled water. Removal of bacteria was accomplished using antibiotics (150 $\mu$g/$m\ell$ ampicillin and 25 $\mu$g/$m\ell$ neomycin) and colonizing on CB solid medium prepared from 0.7% agarose at 3$0^{\circ}C$ under 40 $\mu$ mol m$^{-2}$ s$^{-1}$ light. Among 26 strains of the Microcystis species, only three strains were axenically established. The three strains were examined by PCR-amplified 16S rRNA gene and 16S rRNA sequencing. The similarities were 99.5 ~100% with M. aeruginosa AF 139292.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.958-963
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• 2008

A series of experiments were conducted to assess the effectiveness of rhizobacteria containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase for growth promotion of peas under drought conditions. Ten rhizobacteria isolated from the rhizosphere of different crops (peas, wheat, and maize) were screened for their growth promoting ability in peas under axenic condition. Three rhizobacterial isolates, Pseudomonas fluorescens biotype G (ACC-5), P. fluorescens (ACC-14), and P. putida biotype A (Q-7), were selected for pot trial on the basis of their source, ACC deaminase activity, root colonization, and growth promoting activity under axenic conditions. Inoculated and uninoculated (control) seeds of pea cultivar 2000 were sown in pots (4 seeds/pot) at different soil moisture levels (25, 50, 75, and 100% of field capacity). Results revealed that decreasing the soil moisture levels from 100 to 25% of field capacity significantly decreased the growth of peas. However, inoculation of peas with rhizobacteria containing ACC deaminase significantly decreased the "drought stress imposed effects" on growth of peas, although with variable efficacy at different moisture levels. At the lowest soil moisture level (25% field capacity), rhizobacterial isolate Pseudomonas fluorescens biotype G (ACC-5) was found to be more promising compared with the other isolates, as it caused maximum increases in fresh weight, dry weight, root length, shoot length, number of leaves per plant, and water use efficiency on fresh and dry weight basis (45, 150, 92, 45, 140, 46, and 147%, respectively) compared with respective uninoculated controls. It is highly likely that rhizobacteria containing ACC deaminase might have decreased the drought-stress induced ethylene in inoculated plants, which resulted in better growth of plants even at low moisture levels. Therefore, inoculation with rhizobacteria containing ACC deaminase could be helpful in eliminating the inhibitory effects of drought stress on the growth of peas.

• Parasites, Hosts and Diseases
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• v.56 no.1
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• pp.71-74
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• 2018

Soluble antigens from an axenic culture of Entamoeba histolytica were used to develop a commercial ELISA kit to quantify anti-E. histolytica antibodies in sera of patients with extraintestinal amebiasis in non-endemic settings. The diagnostic specificity and sensitivity of the test were assessed retrospectively using 131 human serum samples with amoebic serologic status available. They were selected according to their results in immunofluorescence (IFAT) and were separated in 2 sample categories: 64 sera with positive results by IFAT and 67 with negative results by IFAT. The sensitivity and specificity of the ELISA kit were assessed at 95.0% and 94.0% compared to the IFAT. The test can be useful to exclude a potential diagnosis of amebiasis and could be used as a screening method since ELISA is an automated technique.

• Mycobiology
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• v.38 no.3
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• pp.225-228
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• 2010

We studied the resistance of Cenococcum geophilum and Suillus granulatus isolates to NaCl during growth under axenic culture conditions. C. geophilum isolates displayed variations in NaCl resistance; mycelial growth of most isolates was inhibited above 200mM. All isolates of S. granulatus were tolerant to high NaCl content.

• BMB Reports
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• v.45 no.2
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• pp.91-95
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• 2012

Glutamate dehydrogenase from axenic bacterial cultures of a new microorganism, called GWE1, isolated from the interior of a sterilization drying oven, was purified by anion-exchange and molecular-exclusion liquid chromatography. The apparent molecular mass of the native enzyme was 250.5 kDa and was shown to be an hexamer with similar subunits of molecular mass 40.5 kDa. For glutamate oxidation, the enzyme showed an optimal pH and temperature of 8.0 and $70^{\circ}C$, respectively. In contrast to other glutamate dehydrogenases isolated from bacteria, the enzyme isolated in this study can use both $NAD^+$ and $NADP^+$ as electron acceptors, displaying more affinity for $NADP^+$ than for $NAD^+$. No activity was detected with NADH or NADPH, 2-oxoglutarate and ammonia. The enzyme was exceptionally thermostable, maintaining more than 70% of activity after incubating at $100^{\circ}C$ for more than five hours suggesting being one of the most thermoestable enzymes reported in the family of dehydrogenases.

• ALGAE
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• v.17 no.3
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• pp.153-159
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• 2002

Partial 16S rRNA gene sequences of seven cyanophycean strains from the National Instiute of Environmental Research of Korea - Microcystis aeruginosa, M. aeruginosa f. aeruginosa, M. ichthyoblade, M. viridis, Anabaena flos-aquae, and Oscillatoria sancta - were analyzed and the phylogenetic relationship of Microcystis among Cyanophyceae were evaluated. Based on sequence analysis results, Microcystis is monophyletic, the clade of which supported 100% bootstrap tress, and distinguished clearly from the other taxa. Therefore, the partial 16S rRNA gene sequences can be a useful and efficient tool for distinguishing Microcystis from other cyanophycean without axenic culture or cloning.

• The Plant Pathology Journal
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• v.19 no.2
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• pp.75-78
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• 2003

A lichen-forming fungus was successfully isolated by discharged spore method from Korean lichen (Hetero-dermia sp.) and cultivated in pure culture. The isolate JR0012 inhibited mycelial growth of several plant-pathogenic fungi. Mycelial growth of the four Pythium spp. tested was completely inhibited. Potato dextrose broth was found to be the medium favorable for large-scale production of antibiotics from the isolate. Anti-fungal substances produced in axenic culture were partially purified. This is the first report in Korea of lichen-forming fungus successfully isolated and which exhibited strong antifungal activity against plant-pathogenic fungi, especially the four Pythium spp..

• Journal of Plant Biotechnology
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• v.7 no.3
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• pp.169-174
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• 2005

The optimal culture conditions were studied for plant regeneration from mesophyll protoplasts of Solanum sisymbriifolium. Axenic seedlings of S. sisymbriifolium were used as a explant for protoplast culture. Many viable protoplasts were isolated by incubating leaf slices in an enzyme solution containing 0.25% Meicerase and 0.05% Macerozyme for 16 hr at $25^{\circ}C$ without shaking. Protoplast density of $5.0{\times}10^4\;ml^{-1}$ in Kao medium containing 5.0 mg/L NAA, 1.0 mg/L 2,4-D and 1.0 mg/L BA was optimal for colony formation. Most colonies were formed when protoplasts were cultured at $25^{\circ}C$ after initial culture at $30^{\circ}C$ for one week. On the MS agar medium with 1.0 mg/L zeatin, 38.4% of protoplast-derived calli differentiated shoots. These shoots rooted on 1/2MS medium with 5.0 g/L sucrose and 2.5 g/L gellan gum, and developed into whole plants.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.2
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• pp.77-80
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• 2007

Macroalgal tissues can be used as indicating materials for environmental assessment using several algal biotechnology techniques. As bioassay test organisms, macroalgal tissues are required as an axenic state for suitable biological indicators. Callus formation and blade regeneration under suitable culture conditions are also useful for the tests. Quantitative method using tetrazolium chloride or $alamarBlue^{TM}$ is devised on a rapid assessment of the seaweed viability. The use of RT-PCR especially differential display technique should provide the means for the detection and isolation of the responding genes induced by the environmental stress. Seaweed thriving in more environmental changes might contain more diverse biologically active substances.