• Korean Journal of Microbiology
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• v.53 no.1
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• pp.20-28
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• 2017

Physical sterilization methods using ultraviolet radiation and ionizing radiation such as gamma ray and electron beam are applied in various industry fields due to disinfection effects and economic efficiency but may also cause microbial mutation. In this research, Salmonella enterica and Escherichia coli strains were treated with ionizing and ultraviolet radiation and their survival rate, mutation rate, and DNA damage were studied to evaluate the genetic safety. The survival rate of the strains decreased drastically as the irradiation dose of ultraviolet ray, gamma ray, and electron beam increased, and over 90% of the strain was exterminated at a dosage of $0.40{\sim}25.06mJ/cm^3$, 0.11~0.22 kGy, 0.14~0.53 kGy respectively. In SOS / umu-test, genotoxicity causing DNA damage was identified in all samples. In Ames test, back-mutation rate increased to $3.82{\times}10^{-4}$ and $9.84{\times}10^{-6}$ respectively when exposed to ultraviolet ray and gamma ray. At exposure to ultraviolet ray, gamma ray, and electron beam with dosage of over 99.99% extinction rate of S. enterica TA100, back-mutation rate increased 347 times, 220 times, 0.6 times respectively to the spontaneous back-mutation rate. Rifampicin resistance mutation rate of E. coli CSH100 exposed to ultraviolet ray, gamma ray, and electron beam was $2.46{\times}10^{-6}$, $1.66{\times}10^{-6}$, $4.12{\times}10^{-7}$ respectively. Therefore, gamma radiation is effective in microorganism control from the perspective of disinfection and electron beam has the advantage of sterilizing with little DNA damage and bacterial mutation.

• Microbiology and Biotechnology Letters
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• v.14 no.4
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• pp.299-304
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• 1986

The cell volume, cell surface, cell concentration, dry cell weight, frequence of respiratory deficient mutation, resistance against ultraviolet irradiation, fermentation power, DNA contents of haploid diploid, triploid and tetraploid of Saccharomyces cerevisiae strain were investigated. Respiratory deficient mutants by spontaneous mutation were absolved more frequently in the haploid than in the diploid, triploid and tetraploid. And cell volume, cell surface, cell concentration, dry cell weight, resistance against ultraviolet irradiation, fermentation power, and DNA contents were significantly increased as the ploidy increased.

• Journal of the Korean Medical Association
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• v.61 no.11
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• pp.644-648
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• 2018

The incidence of skin cancer has continuously increased in Korea, probably due to sun exposure and increases in the aging population. Ultraviolet light, a well-known risk factor for skin cancer, can cause DNA damage, mutation, and immune suppression, followed by abnormal proliferation. To prevent photocarcinogenesis, the appropriate use of sunscreen should be emphasized. Using broad-spectrum sunscreens with sun protection factor values of 15 or higher and frequent reapplication are recommended. Controversy exists about whether vitamin D synthesis is inhibited by the use of sunscreen. However, considering that skin cancer most commonly develops on the head and neck area, applying it to the face and neck is reasonable in terms of balancing the risk-benefit ratio.

• Fisheries and Aquatic Sciences
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• v.15 no.2
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• pp.145-150
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• 2012

An improved strain of the red seaweed Porphyra suborbiculata containing an increased amount of the essential amino acid L-lysine was obtained through mutation and analog enrichment. Mutagenesis using a 10% lethal dose of ultraviolet irradiation and an enrichment culture with the L-lysine analog aminoethyl-L-cysteine (AEC) was repeated to select the most productive strain using monospores of P. suborbiculata. The concentrations of AEC required to produce 50 and 100% inhibition of survival were 60 and 115 mM in the parent strain, and 72 and 135 mM in the selected AEC-resistant strain, respectively. The AEC-resistant strain, L130, produced 1.74-fold more lysine compared to its parent strain. Thus, mutagenesis with analog enrichment shows promise for selecting seaweed strains that can overproduce this essential amino acid.

• Journal of Marine Bioscience and Biotechnology
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• v.6 no.1
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• pp.26-30
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• 2014

Chlorella vulgaris, a genus of single-cell green algae, is considered to be a very essential resource for the higher value-added business including functional food and biodiesel, due to its high contents of protein, carbohydrate and lipid. In this study, ultraviolet rays were irradiated in order to induce the mutation of C. vulgaris. After inducing the mutation, UV1-20 mutant, high in lipid was selected and its cell growth rate, dry weight, pigment content and lipid content were measured. The growth rate of the UV1-20 mutant was increased almost 1.5 times than the wild type, but pigment contents of chlorophyll and carotinoid were decreased. In addition, the lipid content of UV1-20 was increased 1.8 times than the wild type. Therefore, C. vulgaris mutant, isolated in this study, is considered to have sufficient potential to be used as a material for the higher value-added business.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2004.10a
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• pp.29-34
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• 2004

Reduction in stratospheric ozone layer increases the amount of ultraviolet-B radiation (UVB: 280-320 nm) that reaches the earth ’ s surface. UVB radiationcan damage plants, resulting in decrease in growth and productivity. UVB-augmentation studies have indicated that the sensitivity to UVB radiation in plants varies among the species and cultivars. However. there are no definitive answers for the mechanisms of UVB-resistance in higher plants and for bioengineering design and development of UVB-tolerant plants. We have been studying physiological and biochemical aspects of the effects of UVB radiation on growth and yield of rice COryza sativa LJ. aiming to clarify the mechanism of resistance to UVB radiationin rice. At this meeting. weintroduce our research as followed: (1) supplementary UVB radiation has inhibitory effects on the growth. yield and grain development of rice; (2) UVB sensitivity of rice varies widely among cultivars; (3) among Japanese rice cultivars. Sasanishiki. a leading variety in northeast Japan. is more resistant to UVB. while Norin 1. a progenitor of Sasanishiki. is less resistant; (4)UV-sensitive Norin 1 cultivar is deficient in photorepair of UVB-induced cyclobutane pyrimidine dimer (CPD). and this deficiency results from one amino acid residue alteration of CPD photolyase. These results suggest that spontaneously occurring mutation in CPD photolyase gene could lead to difference in UVB sensitivity in rice. and that CPD photolyase might be a useful target for improving UVB-sensitivity in rice by selective breeding or bioengineering of UVB-tolerant rice.

• Mycobiology
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• v.39 no.1
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• pp.20-25
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• 2011

Spores of Aspergillus sp. SU14 were treated repeatedly and sequentially with $Co^{60}$ ${\gamma}$-rays, ultraviolet irradiation, and N-methyl-N'-nitro-N-nitrosoguanidine. One selected mutant strain, Aspergillus sp. SU14-M15, produced cellulase in a yield 2.2-fold exceeding that of the wild type. Optimal conditions for the production of cellulase by the mutant fungal strain using solid-state fermentation were examined. The medium consisted of wheat-bran supplemented with 1% (w/w) urea or $NH_4Cl$, 1% (w/w) rice starch, 2.5 mM $MgCl_2$, and 0.05% (v/w) Tween 80. Optimal moisture content and initial pH was 50% (v/w) and 3.5, respectively, and optimal aeration area was 3/100 (inoculated wheat bran/container). The medium was inoculated with 25% 48 hr seeding culture and fermented at $35^{\circ}C$ for 3 days. The resulting cellulase yield was 8.5-fold more than that of the wild type strain grown on the basal wheat bran medium.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.140-146
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• 1991

Mutation experiments were performed to select the mutant of Aspergillus niger 55, which had lost almost all the ability to produce transglucosidases but retained that of high productivity of raw meal saccharifying enzyme, by means of successive induction with N-methyl-N'-nitro-N-nitrosoguanidine(MNNG), ultraviolet(UV) light, and ${\gamma}$-rays. Also, we used the mutant enrichment techniques, such as liquid culture-filtration procedure and differential heat sensitivity of conidia, in order to increase the possibility of obtaining a mutant. The glucoamylase productivity of mutant PFST-38 was 11 times higher than that of the parent strain. The mutant PFST-38 was morphologically identical to the parent strain, except for the size of conidia, the tendency to form conidia and the lenght of conidiophore. Asp. niger mutant PFST-38 apeared to be useful for the submerged production of the raw corn meal saccharifying enzyme.

• Molecular & Cellular Toxicology
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• v.1 no.2
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• pp.111-115
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• 2005

Ultraviolet (UV) radiation to mammalian skin is known to alter cellular function via generation of Reactive Oxygen Species (ROS), DNA damage and DNA lesions, such as pyrimidine dimmers and photoproducts, which could lead to DNA mutation if they are not repaired. In this study, we have investigated the reduction of DNA damage and of apoptosis with a particular attention to genetic effect of paeoniflorin in Normal Human Epidermal Keratinocytes (NHEK). After UVB irradiation from $10\;to\;500mJ/cm^{2}$ to NHEK, Mean Tail Moments (MTM) were increased with UVB dose increase. The greatest amount of strand breaks was induced at $500mJ/cm^{2}$ of UVB. Even at the lowest dose of UVB ($10mJ/cm^{2}$), change in MTM was detected (P<0.0001). Pretreated cell with 0.1% paeoniflorin maximally reduced the level of DNA damage to about 21.3%, compared to untreated cell. In the lower concentrations less than 0.01% of paeoniflorin, MTM had a small increase but paeoniflorin still had reductive effects of DNA damage. We measured the apoptosis suppression of paeoniflorin with annexin V flous staining kit. As we observed under the fluorescence microscopy to detect apoptosis in the irradiated cell, the fluorescence intensity was clearly increased in the untreated cell, but decreased in treated cells with paeoniflorin. These results suggest that paeoniflorin reduces the alteration of cell membranes and prevents DNA damage. Therefore, the use of paeoniflorin as a free radical scavenger to reduce the harmful effects of UV lights such as chronic skin damage, wrinkling and skin cancer can be useful to prevent the formation of photooxidants that result in radical damage.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1570-1578
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• 2016

Commercial application of laccase is often hampered by insufficient enzyme stocks, with very low yields obtained from natural sources. This study aimed to improve laccase production by mutation of a Coriolopsis gallica strain and to determine the biological properties of the mutant. The high-yield laccase strain C. gallica TCK was treated with N-methyl-N-nitro-N-nitrosoguanidine and ultraviolet light. Among the mutants isolated, T906 was found to be a high-production strain of laccases. The mutant strain T906 was stabilized via dozens of passages, and the selected ones were further processed for optimization of metallic ion, inducers, and nutritional requirements, which resulted in the optimized liquid fermentation medium MF9. The incubation temperature and pH were optimized to be 30℃ and 4.5, respectively. The mutant strain T906 showed 3-times higher laccase activity than the original strain TCK under optimized conditions, and the maximum laccase production (303 U/ml) was accomplished after 13 days. The extracellular laccase isoenzyme 1 was purified and characterized from the two strains, respectively, and their cDNA sequence was determined. Of note, the laccase isoenzyme 1 transcription levels were overtly increased in T906 mycelia compared with values obtained for strain TCK. These findings provide a basis for C. gallica modification for the production of high laccase amounts.