• Journal of Microbiology and Biotechnology
• /
• v.29 no.6
• /
• pp.897-904
• /
• 2019

Monascus purpureus recombinant mppC and mpp7 knockout strains were subjected to extractive fermentation in the context of azaphilone pigment production. Inclusion of Diaion HP-20 resin resulted in the selective production of unreduced azaphilone congeners, in addition to the early intermediate FK17-P2a, from ${\Delta}mppC$ and ${\Delta}mpp7$ strains that would otherwise mainly produce reduced congeners. Structural determination of two novel unreduced azaphilones from the ${\Delta}mpp7$ strain was accomplished. The unreduced azaphilone compound was converted into the cognate reduced congener in recombinant M. purpureus strains, demonstrating its intermediate role in azaphilone biosynthesis. This study demonstrates the possibility that extractive fermentation with Diaion HP-20 resin can be used to obtain cryptic azaphilone metabolites.

• Animal Systematics, Evolution and Diversity
• /
• v.35 no.2
• /
• pp.41-48
• /
• 2019

Pseudacrobeles(Pseudacrobeles) variabilis(Steiner, 1936) Steiner, 1938 and P. (Bunobus) pseudolatus($Hern{\acute{a}}ndez$, 1990) De Ley, Siddiqi and $Bostr{\ddot{o}}m$, 1993 belonging to the family Cephalobidae Filipjev, 1934 are newly reported from South Korea. Pseudacrobeles (Pseudacrobeles) variabilis is distinguished from its congeners by having distinctly setiform cephalic probolae, three rounded or knob-shaped labial probolae and longer female tail. Pseudacrobeles (Bunobus) pseudolatus is distinguished from its congeners by having visibly lateral lips, a short post-uterine sac, elongated conoid tail in the female, and acute mucro on the tails of both sexes. In this study, details of the morphological characters and morphometrics of Korean populations of P. (P.) variabilis and P. (B.) pseudolatus are described and illustrated based on optical microscopy.

• Bulletin of the Korean Chemical Society
• /
• v.5 no.4
• /
• pp.158-162
• /
• 1984

The crystal structure of chloramphenicol base, $C_9H_{l2}N_2O_4$, the deacylated base of antibiotic chloramphenicol, has been determined by X-ray diffraction techniques using diffractometer data obtained by the ${\omega}-2{\theta}$ scan technique with CuK${\alpha}$ radiation from a crystal with space group symmetry $P2_12_12_1$ and unit cell parameters a = 22.322(6), b = 7.535(6), c = 5.781(5) ${\AA}$. The structure was solved by direct methods and refined by full-matrix least-squares to a final R = 0.051 for the 573 observed reflections. The overall conformation of the base is quite different from those of the chloramphenicol congeners which are similar despite the presence of many rotatable single bonds. The propane chain in the base is bent with respect to the phenyl ring, while it is extended in the chloramphenicol congeners. There is no intramolecular hydrogen bond between the hydroxyl groups of the propanediol moiety. All of the molecules in the crystal lattice are connected by a three-dimensional hydrogen bonding network.

• Journal of Species Research
• /
• v.12 no.1
• /
• pp.48-54
• /
• 2023

Foraminifera are unicellular eukaryotes widely distributed in marine and transitional marine environments. They play important roles in marine food webs and geochemical cycles and have physiological properties like the formation of calcareous tests and nitrogen respiration. Research on species diversity, distribution and endemism are essential in biogeography and biodiversity conservation. Here, we report three unrecorded species of foraminifera (Hemirotalia foraminulosa, Planispirillina denticulogranulata and Oolina brevisolenia) collected from Jeju Island and the South Sea (Korea). Planispirillina denticulogranulata is the second Planispirillina species recorded in Korea, which can be distinguished from congeners by its tubercles on the ventral side and grooves on the spiral suture. Hemirotalia foraminulosa is differentiated from the only congener H. calvifacta by multiple-scattered pits on the umbilicus, and it is the first report of Hemirotalia from Korean water. Oolina brevisolenia has specific bifurcating costae that characterize it from other congeners. This study contributes to documentation of the foraminiferal biodiversity in Korea, moreover, provides an essential basis for the expanded studies on modern foraminifera.

• Journal of Species Research
• /
• v.12 no.4
• /
• pp.307-312
• /
• 2023

Oxytricha multilineata, Mixophrya pantanalensis pantanalensis, and Caudiurostyla sinensis were isolated from soil samples collected from Cheongju-si and Yeoju-si, confirmed as new to South Korea. Oxytricha multilineata was distinguished from other congeners by seven dorsal kineties and dorsal bristles about 15 ㎛ long. Mixophrya pantanalensis pantanalensis was characterized by five to seven lithosomes and six dorsal kineties. Caudiurostyla sinensis was characterized by colorless cortical granules present, 10-14 midventral pairs, 7-9 left and 6-9 right marginal rows and four or five dorsal kineties. We determined the ribosomal DNA sequences (including 18S rDNA, ITS1, 5.8S rDNA, ITS2, and partial 28S rDNA) from above three species. And the genetic distances were compared with their congeners.

• Analytical Science and Technology
• /
• v.16 no.4
• /
• pp.325-332
• /
• 2003

To analyze co-planar PCBs in food, the isotopic dilution method by high resolution gas chromatography/high resolution mass spectrometry was applied. Among 209 PCB congeners, 12 congeners (#77, #81, #126, #169, #105, #114, #118, #123, #156, #157, #167 and #189) were chosen as target compounds that were toxic congeners re-assessed by WHO in 1998. Milk and milk products including cheese and butter were collected as food samples. Samples were homogenized, spiked with the known amount of the standard mixture and extracted. After extraction, extracts were cleaned up by sulfuric acid impregnated silica gel, purified on silica gel and alumina column chromatography and then analyzed by HRGC/HRMS. As results, the overall recoveries were ranged from 83% to 106% and the limit of detection was about 0.1 pg/g at signal/noise>3. Levels of targets in the selected food samples were 0.001~0.107 pgWHO-TEQ/g.

• Korean Journal of Environmental Agriculture
• /
• v.24 no.2
• /
• pp.139-145
• /
• 2005

All 209 PCB congeners were analyzed in cheese produced in Korea and Canada. 5 Korean and 10 Canadian cheeses were purchased in supermarket in their native countries. 93 PCB congeners were found in Korean cheese; 83 congeners were detected in Canadian cheese. Total PCB concentrations were 299.81 and 200.96 pg/g w.w. in Korean and Canadian cheeses respectively; PCB concentration was 1.5 times higher in Korean than Canadian cheese. Korean TEQ concentration (0.0067 pg-TEQ/g w.w.) in cheese was similar to in Canadian cheese (0.0064 pg-TEQ/g w.w.). These PCB concentrations range was low level compared with that of other cheeses globally. The correlation coefficient $(R^2)$ of regression was high (0.752) between each PCB congener concentration in both Korean and Canadian cheese.

• Analytical Science and Technology
• /
• v.26 no.2
• /
• pp.113-119
• /
• 2013

The objective of this study was to understand the content characteristic of polybrominated biphenyl ethers in indoor household dust. Polybrominated diphenyl ethers (PBDEs) are widely used as additive brominated flame retardants (BFR) in electrical and electronic equipment, and insulation in the indoor environment, and may be released indoors via volatilization or as dusts. The indoor household dust samples were collected from January to December in 2011 and measured for the concentrations, congener profiles and possible sources of PBDEs. The concentrations of 22 congeners of PBDEs (the sum of PBDEs 47, 49, 66, 71, 77, 85, 99, 100, 119, 126, 138, 153, 154, 156, 183, 184, 191, 196, 197, 206, 207 and 209) were 35.22~575.88 ng/g for apartment dust samples and 524.44 ng/g for laboratory dust sample. The eight congeners of BDE-47, 153, 183, 196, 197, 206, 207, and 209 are detected in the more than 1 ng/g. The three congeners of BDE-206, 207 and 209 in all dust samples were detected.

• Journal of Environmental Health Sciences
• /
• v.40 no.2
• /
• pp.147-156
• /
• 2014

Objectives: This study was carried out to examine whether the apparent photolysis with or without sensitizers [NaOH and humic acid (HA)] was prompted photodegradation of polychlorinated biphenyl (PCB) in aqueous solution. Methods: PCBs photodegradation occurred using fluorescence black lamps at ${\lambda}_{max}=300nm$. PCB congeners were exposed in 10 ppm HA or 0.05N NaOH solutions, to investigate the decreasing profile of PCB concentration with time. The PCBs were then analyzed by gas chromatography/mass spectrometry (GC-MS). Reductive degradation profile of PCB congeners in the presence of both sensitizers under oxygen-saturated protic conditions was described using the wind-rose diagrams. Results: Use of HA or NaOH decreased PCB concentration with time in the dark and on irradiation, indicating that photolysis underwent through reductive dechlorination through energy transfer and possibly with reactive oxygens. The dechlorination was marked by a chromatographic shift, observed in the GC-MS plots. Therefore it is logical to assume that increasing the dose of sensitizers would increase the photodegradation rates of PCBs. The half-lives of pentachloro-PCB (penta-3) in 0.05N NaOH and 10 ppm HA were estimated at about 47 hours and 39 hours, respectively, under the same experimental conditions of photolysis. It was found that the rate of photolysis of pentachloro-PCB in aqueous solution followed apparent first-order kinetics compared to other congeners. Conclusion: Photochemical degradation (using 328 nm UV light) of penta- and hexa-PCBs in HA or alkaline solution is a viable method for pretreatment method. The results are helpful for the further comprehension of the reaction mechanism for photolytic dechlorination of PCBs in aquatic system.

• Food Science and Biotechnology
• /
• v.14 no.1
• /
• pp.73-76
• /
• 2005

The acaricidal activities of 12 commercial constituents derived from Eugenia caryophyllata leaf oils against Dermatophagoides farinae, D. pteronyssinus and Tyrophagus putrescentiae adults were examined using an impregnated fabric disk application and compared with that of the commercial benzyl benzoate as synthetic acaricide. On the basis of $LD_{50}$ values, the most toxic compound was methyl eugenol ($4.13\;{\mu}g/cm^2$), followed by methyl isoeugenol ($4.19\;{\mu}g/cm^2$), isoeugenol ($4.29\;{\mu}g/cm^2$), eugenol ($4.94\;{\mu}g/cm^2$), and acetyl eugenol ($13.91\;{\mu}g/cm^2$) against D. farinae. In the case of D. pteronyssinus, isoeugenol ($2.93\;{\mu}g/cm^2$) was the most toxic, followed by methyl isoeugenol ($3.28\;{\mu}g/cm^2$), methyl eugenol ($3.87\;{\mu}g/cm^2$), eugenol ($3.92\;{\mu}g/cm^2$), and acetyl eugenol ($7.21\;{\mu}g/cm^2$). These results suggest that D. pteronyssinus may be controlled more effectively by the application of eugenol congeners than D. farinae. In comparison with synthetic acaricides, the acaricidal activities of eugenol, isoeugenol, methyl eugenol, and methyl isoeugenol were about 1.9-2.2 times more toxic than benzyl benzoate. Furthermore, the most toxic constituent against T. putrescentiae was exhibited on eugenol ($10.11\;{\mu}g/cm^2$), followed by methyl eugenol ($38.67\;{\mu}g/cm^2$) and acetyl eugenol ($70.09\;{\mu}g/cm^2$), but no activity was observed for isoeugenol and methyl isoeugenol. The results suggested that eugenol congeners may be useful as a new source for selective control of house dust mites and stored food mites.