• Microbiology and Biotechnology Letters
• /
• v.13 no.1
• /
• pp.71-77
• /
• 1985

A bacterium which grows on cyclohexanol as sole carbon and energy source was isolated from sludge of industrial areas in Taegu and identified as Acinetobacter calcoaceticus C-15. The growth medium for the optimal culture condition was composed of 0.2% cyclohexanol, 0.11% $NH_4Cl$, 0.05% $KH_2PO_4$, 0.2% $K_2HPO_4$, 0.02% $MgSO_4{\cdot}7H_2O$, and 0.05% yeast extracts. The optimal pH value and temperature for the growth were 7.2 and $33^{\circ}C$, respectively. Specific growth rate of A. calcoaceticus C-15 at $33^{\circ}C$ on the cyclohexanol and cyclohexanone was $0.27hr^{-1}$ and $0.15hr^{-1}$, respectively. Growth yield for cyclohexanol was 1.0. The bacteria utilized ethanol, 1-butanol, 1-pentanol, and cyclohexanol as a carbon source but not methanol, 1-hexanol, m-cresol, glycerol, and cyclohexane. The bacteria grew on benzoate, adipate, acetate, and citrate, but did not on salicylate, phthalate, p-hydroxybenzoate, and gluconate. A calcoaceticus C-15 did not utilize all kind of sugars other than xylose. Cell-free extracts contained $NAD^+$-linked cyclohexanol dehydrogenase which catalized the oxidation of cyclohexanol to cyclohexanone.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.10
• /
• pp.1213-1222
• /
• 2009

The search for diverse plant growth-promoting (PGP) diazotrophic bacteria is gaining momentum as efforts are made to exploit them as biofertilizers for various economically important crops. In the present study, 17 diazotrophic strains belonging to eight different genera isolated from rice paddy fields were screened for multiple PGP traits and evaluated for their inoculation effects on canola and rice plants. All of the strains tested positive for 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity and production of indole 3-acetic acid (IAA) and ammonia ($NH_3$). Additionally, four of the strains were able to solubilize phosphorus (P), five tested positive for zinc (Zn) solubilization and sulfur (S) oxidation, and eight strains produced siderophores. Based on the presence of multiple PGP traits, 10 strains were selected for inoculation studies. Treatment with Herbaspirillum sp. RFNB26 resulted in maximum root length (54.3%), seedling vigor, and dry biomass in canola, whereas Paenibacillus sp. RFNB4 exhibited the lowest activity under gnotobiotic conditions. However, under pot culture conditions, Paenibacillus sp. RFNB4 significantly increased plant height and dry biomass production by 42.3% and 29.5%, respectively. Canola plants and rhizosphere soils inoculated with Bacillus sp. RFNB6 exhibited significantly higher nitrogenase activity. In greenhouse experiments, Serratia sp. RFNB18 increased rice plant height by 35.1%, Xanthomonas sp. RFNB24 enhanced biomass production by 84.6%, and rice rhizosphere soils inoculated with Herbaspirillum sp. RFNB26 exhibited the highest nitrogenase activity. Our findings indicate that most of the selected strains possess multiple PGP properties that significantly improve the growth parameters of the two plants when tested under controlled conditions.

• Microbiology and Biotechnology Letters
• /
• v.41 no.2
• /
• pp.153-159
• /
• 2013

A mannitol dehydrogenase (MDH; EC 1.1.1.67) gene was cloned from the Sinorhizobium meliloti 1021 (KCTC 2353) genome and expressed in Escherichia coli. It was seen to have an open reading frame consisting of 1,485 bp encoding 494 amino acids (about 54 kDa), which shares approximately 35-55% of amino acid sequence identity with some known long-chain dehydrogenase/ reductase family enzymes. The recombinant S. meliloti MDH (SmMDH) showed the highest activity at $40^{\circ}C$, and pH 7.0 (D-fructose reduction) and pH 9.0 (D-mannitol oxidation), respectively. SmMDH could catalyze the oxidative/reductive reactions between D-mannitol and D-fructose in the presence of $NAD^+/NADH$ as a coenzyme, but not with NADP+/NADPH. These results indicate that SmMDH is a typical $NAD^+/NADH$-dependent mannitol dehydrogenase.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.2
• /
• pp.137-143
• /
• 2006

Three candidate processes(ozone alone, UV alone and ozone/UV combined processes) were evaluated for the removal of diethyl phthalate(DEP). Of the candidates, the ozone/UV process showed the highest removal efficiency of DEP. To elucidate a major oxidant for DEP oxidation in the ozone/UV process, the effects of pH and hydroxyl radical($OH^{\circ}$) scavenger were investigated. As a result, it was found that $OH^{\circ}$ plays a important role for DEP elimination. Meanwhile, the direct reaction between ozone and DEP was negligible. Observing the pseudo first-order rate of DEP removal in ozone alone and ozone/UV processes, the different pattern was obtained from two processes. The ozone/UV process was well plotted following the pseudo first-order. but in the ozone alone process the rate was divided into fast and slow phases. DEP degradation characteristics in ozone alone and ozone/UV was also investigated by observing the HPLC spectrum. We detected unknown compounds that were guessed to DEP byproducts and observed the formation and disappearance of the unknown compounds according to reaction time. Observing of high removal of TOC in ozone/UV combined process, it was found that DEP and DEP byproducts are completely oxidized by ozone/UV combined process.

• Resources Recycling
• /
• v.18 no.5
• /
• pp.19-25
• /
• 2009

Molybdenite concentrate ($MoS_2$) is the major mineral for the molybdenum industry, of which the industrial processing is first converted to technical grade molybdenum trioxide ($MoO_3$) by its oxidative roasting and purification, used as a raw material for manufacturing several molybdenum compounds. In the present work, detailed experimental results for the oxidative roasting of low grade Mongolian molybdenite concentrate are presented. The experiments were carried out in the temperature range of 793 to 823 K under an oxygen partial pressure range of 0.08 atm to 0.21 atm by using a thermogravimetric analysis technique. The molybdenite concentrate was an average particle size of $67\;{\mu}m$. In the oxidative roasting of low grade Mongolian molybdenite concentrate, more than 95% of molybdenite was converted to molybdenum trioxide in 60 min. at 828 K. The lander equation was found to be useful in describing the rates of the oxidative roasting and the reaction order with respect to oxygen concentration in a gaseous mixture with nitrogen was 0.11 order.

• Journal of Korean Society of Water and Wastewater
• /
• v.21 no.5
• /
• pp.559-569
• /
• 2007

The purposes of this study were to find the main foulant of membrane and the optimal chemical cleaning method for MF(microfiltration) drinking water treatment system using D dam water as water source. The MF pilot plant which can treat maximum $500m^3/d$ consisted of 3 racks and was operated for 10 months under various operation conditions. After 10 months operation, $1^{st}$ and $2^{nd}$ rack of membrane pilot plant system were cleaned chemically and the degree of the restoration of the fouled membrane in terms of the pure water flux was detemnined. Inorganic compounds which contained in chemical cleaning waste was analyzed by Inductively Coupled Plasma (ICP). One membrane module for 3rd rack was disjointed and membrane fouling materials, especially inorganic compounds were investigated by Electron Probe Microanlysis (EPMA) to elucidate the reason of TMP increase. And also, the various chemical reagents (1N HCl or $H_2SO_4$, oxalic acid as acid and 0.3% NaOCl as alkali) were tested by combination of acid and alkali to determine the optimal chemical cleaning method for the MF system using micro-modules manufactured using the disjointed module. It was verified that the inside and outside of membrane module was colorized with black. As a result of the quantitative and semi-qualitative analysis of membrane foulant by ICP, most of inorganic foulant was manganese which is hard to remove by inorganic acid such as HCI. Especially, it was observed by EPMA that Mn was attached more seriously in inside surface of membrane than in outside surface of that. It was supposed that Mn fouling in inside surface of membrane might be caused by the oxidation of soluble manganese (Mn(II)) to insoluble manganese ($MnO_2$) by chlorine containing in backwashing water. The optimal cleaning method for the removal of manganese fouling was consecutive cleaning with the mixture of 1N HCl and 1% of oxalic acid, 0.3% NaOCl, and 1N HCl showing 91% of the restoration of the fouled membrane.

• Korean Journal of Microbiology
• /
• v.48 no.2
• /
• pp.156-162
• /
• 2012

A mannitol dehydrogenase (StMDH) gene was cloned from Salmonella typhimurium LT2 (KCTC 2421) and overexpressed in Escherichia coli. It has a 1,467 bp open reading frame encoding 488 amino acids with deduced molecular mass of 54 kDa, which shares approximately 36% of amino acid identity with known long-chain dehydrogenase/reductatse (LDR) family enzymes. The recombinant StMDH showed the highest activity at $30^{\circ}C$, and pH 5.0 and 10.0 for D-fructose reduction and D-mannitol oxidation, respectively. On the contrary, it has no activity on glucose, galactose, xylose, and arabinose. StMDH can catalyze the oxidative/reductive reactions between D-fructose and D-mannitol only in the presence of $NAD^+$/NADH as coenzymes. These results indicate that StMDH is a typical $NAD^+$/NADH-dependent mannitol dehydrogenase (E.C. 1.1.1.67).

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.26 no.2
• /
• pp.62-66
• /
• 2016

In this study, it was investigated that characteristic of crack-self-healing of hot-pressed SiC. SiC ceramics was sintered with $Al_2O_3$ and $Y_2O_3$ sintering additive by hot press. Sintering was performed in hot-press furnace in flowing argon (Ar), holding for 3 hr under $1950^{\circ}C$ and 50 MPa. The sintered SiC was machined into 3-point bending strength specimen of $3{\times}4{\times}40mm$, and introduced pre-crack by Vickers indentation at 49.6 N. Specimens were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), 3-point bending strength after heat treatment at $1200{\sim}1400^{\circ}C$ for 1~10 hr. The best crack-self-healing ability was achieved 770 MPa 3-point bending strength by heat treatment at $1300^{\circ}C$ for 5 hr.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.25 no.3
• /
• pp.116-120
• /
• 2015

$La_2NiO_{4+{\delta}}$ based oxides, a mixed electronic-ionic conductors (MIECs) with $K_2NiF_4$ type structure, have been considerably investigated in recent decades as electrode materials for advanced solid oxide fuel cells (SOFCs) due to their high electrical conductivity, and oxidation reduction reaction (ORR). In this study, structure properties of $La(Ca)_2Ni(Cu)O_{4+{\delta}}$ were studied as a potential cathode for intermediate temperature SOFCs (IT-SOFCs).

• Journal of Korean Society of Forest Science
• /
• v.102 no.3
• /
• pp.331-337
• /
• 2013

Formate dehydrogenase (FDH), catalyzing the oxidation of the formate ion to carbon dioxide, is known as the stress protein in response to drought, low temperature and pathogen infection. To study the functions of FDH in poplar (Populus alba ${\times}$ P. glandulosa), we isolated a FDH cDNA (PagFDH1) and examined its expressional characteristics. The PagFDH1 is 1,499 base pairs long and encodes a putative 388 amino acid protein with an expected molecular mass of 42.5 kDa. The PagFDH1 protein has N-terminal mitochondria signal peptide and $NAD^+$ binding domain. Southern blot analysis indicated that a single copy of the PagFDH1 is present in the poplar genome. PagFDH1 is expressed highly in the suspension cells (especially in the lag and early exponential phases) and moderately in roots, flowers and leaves. ABA-mediated enhanced expression of PagFDH1 in response to drought and salt stress treatments indicates that the gene product could play an important role in the development of stress resistant trees.