• Environmental Analysis Health and Toxicology
• /
• 제20권4호통권51호
• /
• pp.351-358
• /
• 2005

The n -octanol/water partition coefficient (Pow) is one of the most important parameters employed for estimating a chemiral's environmental fate and toxicity. The shake-flask method, one direct experimental method, i.1 prone to experimental artifacts for highly hydrophobic compounds. Thus, a valid method for direct determination of the Pow of highly hydrophobic compounds is needed. The slow -stirring method has been demonstrated to provide reliable log Pow data to log Pow greater than 5. This study was performed to evaluate the accuracy of slow- stirring experiment for determination of log Pow, particularly for highly hydrophobic compounds. 1, 2, 3, 4-tetrachlorobenzene, hexachlorobezene, 2, 2', 3, 3', 5, 5', 6, 6'-octachlorobiphenyl, decachlorobiphenyl, and p, p'-DDT (4.5$\times$0.02, 5.41$\times$0.06, 7.26$\times$0.04, 7.87$\times$0.10, and 6.03$\times$0.06, respectively. The octanol/water partition coefficient by the slow-stirring method were very similar to the literature values. These results indicate that the slow- stirring method allows for reliable determination of log Pow of highly hydrophobic chemicals.

• 한국가정과학회지
• /
• 제1권1호
• /
• pp.103-112
• /
• 1998

면직물에 항균성을 부여하기 위하여 패드-건조(-열처리법)에 의해 키토산처리를 하였다. 분자량이 약 50,000으로 비슷하고 탈아세틸화도가 65∼95％인 4종의 키토산과 분자량이 약 1,800이고 탈아세틸화도가 약 86％인 1종의 키토산올리고머를 사용하였다. 키노산올리고머로 처리한 경우에는 세탁내구력을 증진시키기 위하여 가교제 또는 바인더를 가공처리액에 첨가하였다. 항균성은 쉐이크플라스크법에 의해 공시균 Staphylococcus aureus 와 Proteus vulgaris를 사용하여 측정하였다. 세탁내구력은 AATCC Test Method 60-1986 또는 JIS 0217-104에 따라 20회까지 세탁한 후 항균성을 측정하였다. 실험결과, 항균성은 키토산의 농도와 탈아세틸화도가 증가함에 따라 증가하였으며 열처리 유무는 항균성에 큰 영향을 미치지 않았다. AATCC Test Method 60-1986에 따르면 열처리한 시료의 세탁내구력이 열처리하지 않은 시료보다 우수하였다. 가교제나 바인더의 첨가는 키토산올리고머를 처리한 시료의 항균성을 감소시켰으며, JIS 0217-104에 따라 실험한 결과 세탁내구력 향상에 효과가 없었다.

• 한국결정성장학회지
• /
• 제12권4호
• /
• pp.165-171
• /
• 2002

피치계 탄소섬유로부터 활성탄소섬유를 제조한 후, 이에 대하여 금속를 처리하여 금속-ACFs를 제조하였다. 제조된 금속-ACFs에 대하여 흡착 및 표면특성을 통하여 물리화학적 특성을 제시하였다. BET식으로부터 금속이 처리된 활성 탄소섬유의 비표면적을 구한 결과 Ag-ACF의 경우 136.2~1585$m^2$/g의 범위에, Cu가 처리된 활성탄소섬유에 경우 698.2~896.2$\m^2$/g의 범위에, Ni-ACF의 경우 685.2~898.2$\m^2$/g의 범위에 분포하였다. 또한 $\alpha_s$-법을 사용하여 구한 미세 동공부피는 Ag-ACF에 대하여 0.07~1.2cm^3/g, Cu-ACF에 대하여 0.2~0.3cm^3/g, Ni-ACF에 대하여 0.3~0.7cm^3/g, 의 범위에 분포함을 알 수 있었다. 이와 관련하여 SEM 분석을 통하여 표면성상에 대하여 연구한 결과, 처리된 금속은 섬유표면 주위를 부분적으로 또는 전 범위에 걸쳐서 피복되어 있음이 관찰되었다. 최종적으로 Shake 플라스크법에 의거하여 대장균(E. coli)에 대한 금속-ACFs의 항균특성에 대한 결과로부터 금속의 양이 증가함에 따라 항균효과가 크게 증가함을 알 수 있었다.

• 한국의류학회지
• /
• 제14권3호
• /
• pp.216-221
• /
• 1990

This study was performed for the development of antimicrobial finished nonwoven fabrics with water repellency. And it was aimed to examine the changes of moisture related properties and air permeability of the finished fabrics. Viscose rayon nonwoven fabrics were treated with organic silicon quaternary ammonium salt having carbon numbers of 16, which was synthesized for this study Antimicrobial activity was evaluated by shake flask method and the reactivity of antimicrobial agent was measured by degree of luminescence from inductively coupled plasma. Water repellency of treated specimen was evaluated by dynamic water absorption measurement and air permeability was measured by Frazier method. The results obtained from this study were as follows: 1. Excellent antimicrobial activity was obtained for the high concentration of treatment and the durability of finishing after laundering was better as the treatment concentration was higher 2. Silicon contents taken up by specimen increased with increased treatment concentration. 3. Dynamic water absortion of treated specimen decreased compared to that of untreated. And, it was lowered as the treatment of concentration increased and as the silicon content increased. 4. Moistuie regain and uptake with lapse of time of treated specimen increased compared to those of untreated. But, air permeability of treated specimen decreased.

• 한국염색가공학회지
• /
• 제18권6호
• /
• pp.16-24
• /
• 2006

The purpose of this study is to improve the defects of chitosan crosslinked viscose rayon by ECH and to describe the change of hand of chitosan crosslinked viscose rayon fabrics. The chitosan crosslinked viscose rayon were manufactured by crosslinking process using ECH as crosslinking agent, 2 wt% aqueous acetic acid as a solvent of chitosan and ECH, and 20 wt% aqueous sodium hydroxide as crosslinking catalyst. Viscose rayon were first immersed in the pad bath of the mixed solution of chitosan and ECH, padded up to 100 wt% wet pick-up on weight of fiber(owf), precured on pin frames at $130^{\circ}C$ for 2 minutes, immersed in NaOH solution and finally wash and dry. Antimicrobial properties of the viscose rayon treated with chitosan were measured by the shake flask C.T.M. 0923 test method with staphylococcus aureus(ATCC 6538) as the microorganism. When the concentration of chitosan was increased chitosan crosslinked viscose rayon's LT, WT, B, 2HB and MIU were increased and G, 2HG, SMD, T and $T_m$ were decreased. On the other hand, WT, EM were decreased and RT was increased at $1{\times}10^{-2}M$ ECH. The optimum condition for crosslinking was that ECH concentration was between $1{\times}10^{-2}M\;and\;5{\times}10^{-2}M$. Antimicrobial effects of rayon fabric treated with chitosan was excellent.

• Journal of Microbiology and Biotechnology
• /
• 제26권11호
• /
• pp.1908-1917
• /
• 2016

Wild strain L-6 was subjected to combined mutagenesis, including UV irradiation, atmospheric and room temperature plasma, and ion beam implantation, to increase the yield of 1,3-dihydroxyacetone (DHA). With application of a high-throughput screening method, mutant Gluconobacter oxydans I-2-239 with a DHA productivity of 103.5 g/l in flask-shake fermentation was finally obtained with the starting glycerol concentration of 120 g/l, which was 115.7% higher than the wild strain. The cultivation time also decreased from 54 h to 36 h. Compared with the wild strain, a dramatic increase in enzyme activity was observed for the mutant strain, although the increase in biomass was limited. DNA and amino acid sequence alignment revealed 11 nucleotide substitutions and 10 amino acid substitutions between the sldAB of strains L-6 and I-2-239. Simulation of the 3-D structure and prediction of active site residues and PQQ binding site residues suggested that these mutations were mainly related to PQQ binding, which was speculated to be favorable for the catalyzing capacity of glycerol dehydrogenase. RT-qPCR assay indicated that the transcription levels of sldA and sldB in the mutant strain were respectively 4.8-fold and 5.4-fold higher than that in the wild strain, suggesting another possible reason for the increased DHA productivity of the mutant strain.

• Journal of Microbiology and Biotechnology
• /
• 제27권2호
• /
• pp.306-315
• /
• 2017

Metabolic engineering with a high-yielding mutant, A. terreus AN37, was performed to enhance the production of itaconic acid (IA). Reportedly, the gene cluster for IA biosynthesis is composed of four genes: reg (regulator), mtt (mitochondrial transporter), cad (cis-aconitate decarboxylase), and mfs (membrane transporter). By overexpressing each gene of the IA gene cluster in A. terreus AN37 transformed by the restriction enzyme-mediated integration method, several transformants showing high productivity of IA were successfully obtained. One of the AN37/cad transformants could produce a very high amount of IA (75 g/l) in shake-flask cultivations, showing an average of 5% higher IA titer compared with the high-yielding control strain. Notably, in the case of the mfs transformants, a maximal increase of 18.3% in IA production was observed relative to the control strain under the identical fermentation conditions. Meanwhile, the overexpression of reg and mtt genes showed no significant improvements in IA production. In summary, the overexpressed cis-aconitate decarboxylase (CAD) and putative membrane transporter (MFS) appeared to have positive influences on the enhanced IA productivity of the respective transformant. The maximal increases of 13.6~18.3% in IA productivity of the transformed strains should be noted, since the parallel mother strain used in this study is indeed a very high-performance mutant that has been obtained through intensive rational screening programs in our laboratory.

• Journal of Microbiology and Biotechnology
• /
• 제30권11호
• /
• pp.1670-1679
• /
• 2020

The substantial use of fungal enzymes to degrade lignocellulosic plant biomass has widely been attributed to the extensive requirement of powerful enzyme-producing fungal strains. In this study, a two-step screening procedure for finding cellulolytic fungi, involving a miniaturized culture method with shake-flask fermentation, was proposed and demonstrated. We isolated 297 fungal strains from several cellulose-containing samples found in two different locations in Thailand. By using this screening strategy, we then selected 9 fungal strains based on their potential for cellulase production. Through sequence-based identification of these fungal isolates, 4 species in 4 genera were identified: Aspergillus terreus (3 strains: AG466, AG438 and AG499), Penicillium oxalicum (4 strains: AG452, AG496, AG498 and AG559), Talaromyces siamensis (1 strain: AG548) and Trichoderma afroharzianum (1 strain: AG500). After examining their lignocellulose degradation capacity, our data showed that P. oxalicum AG452 exhibited the highest glucose yield after saccharification of pretreated sugarcane trash, cassava pulp and coffee silverskin. In addition, Ta. siamensis AG548 produced the highest glucose yield after hydrolysis of pretreated sugarcane bagasse. Our study demonstrated that the proposed two-step screening strategy can be further applied for discovering potential cellulolytic fungi isolated from various environmental samples. Meanwhile, the fungal strains isolated in this study will prove useful in the bioconversion of agricultural lignocellulosic residues into valuable biotechnological products.

• 자연과학논문집
• /
• 제11권1호
• /
• pp.159-164
• /
• 1999

유기실리콘 제4급 암모늄염을 이용하여 타올에 향균제를 처리하였을 때의 향균성에 가장 많은 영향을 미치는 처리농도, 시간, 온도에 대한 향균성 변화를 비교 조사하였고, 향균처리 후 물성변화, 내세탁성을 측정하였다. 타올의 향균성에 가장 우수한 향균성을 나타내고 많은 영향을 미치는 처리농도는 3.5%이며, 처리온도 $30^{\circ}C$에서, 처리시간 10분간 향균가공 처리하여도 균감소율이 95% 이상 향균성능을 유지함을 알 수 있었다. 또한 세탁 횟수에 따른 균 감소율은 20회까지 세탁하여도 80%이상 높은 향균성을 나타내었고, 향균제 가공처리 후 측정한 타올의 인장강도 및 신도는 큰 변화가 없었다.

• 한국미생물·생명공학회지
• /
• 제48권3호
• /
• pp.344-357
• /
• 2020

Streptococcus zooepidemicus 유래의 세포외 고분자물질인 히알루론산(hyaluronic acid) (HA)을 대량 생산하기 위해, 균주 개량, 생산배지 및 배양공정 개발에 관한 연구를 수행하였다. HA 고생산성 변이주를 선별하기 위해 약 99%의 사멸률을 보이는 ethylmethane sulfonate (EMS) 처리조건을 적용해서, 지속적인 random screening 방법으로 고생산성, 고안정성의 변이주들을 선별할 수 있었다. HA를 고농도로 생산하기 위해서는, 이 균주의 생화학 및 배양생리적 특성에 기반한 최적 배지개발이 필수적이라고 판단하여, one-factor-at-a-time (OFAT), full factorial design (FFD), steepest ascent method (SAM) 및 response surface method (RSM) (반응표면분석법)을 순차적으로 적용하여 통계적 배지 최적화 실험을 수행하였다. 최적 배지조성에서 플라스크 배양에 의한 HA 생산성은 5.38 g/l로서, 이전 배지(3.54 g/l)에 비해 약 52% 향상된 생산량을 얻을 수 있었다. 또한 선별된 우량균주와 최적화된 생산배지를 이용하여 5 L 발효조에서 배양공정 최적화 연구를 수행하였다. 이 균주의 생리학적 특성을 고려할 때, HA 생산성을 높이기 위해서는 (배양 중 HA 축적으로 인해 고점도를 띠는) 배양액으로의 충분한 용존산소 공급이 매우 중요한 요인인 것으로 판단되었다. 따라서 용존산소 공급과 밀접하게 관련있는 발효조의 교반시스템(교반 날개 종류, 크기 및 배치 등) 및 교반속도에 대한 최적화 연구를 수행하였다. 그 결과, 교반축 하부에는 Rushton turbine-type, 상부에는 marine-type의 확장된 교반날개(기존 대비 직경 1.3배 확장)가 설치된 경우, 450 rpm에서 강화된 혼합력과 충분한 용존산소 공급으로 인해 HA 생산성이 기존 플라스크 배양 대비 약 1.8배(9.79 vs. 5.38 g/l) 더 높은 것으로 확인되었다. 최종적으로 HA 배양공정의 scale-up 가능성을 확인하기 위해, pilot 규모의 50 L 발효조 배양을 최대 300 rpm의 교반속도에서 수행하였다. 처음으로 시도한 50 L 배양임에도 불구하고, HA 최대 생산성 면에서 볼 때, 5 L 발효조 결과와 거의 동일한 수준(98.5%) (9.11 vs 9.25 g/l)의 생산량을 얻을 수 있었다. 반면 지수기 성장단계인 배양 15시간까지의 50 L 배양의 HA 평균생산속도(r_p)는 0.46 g/l/hr로서 0.62 g/l/hr인 5 L 배양 대비 약 74% 정도에 머무는 것으로 나타났다. 따라서 생산 발효조의 scale-up 시, 생산균주의 전단응력 민감성(shear damage)을 함께 고려하면서, 산소전달계수(k_La)를 기반으로 하는 교반시스템에 대한 체계적인 연구가 진행된다면, HA 생산속도도 증가될 수 있는 긍정적인 결과를 얻을 수 있을 것으로 기대된다.