• 문화기술의 융합
• /
• 제8권2호
• /
• pp.349-354
• /
• 2022

본 연구는 PBAT(Poly Butylene Adipate-co-Terephthalate)와 PLA(Poly Lactic Acid)를 사용하여 수지의 컴파운드와 생분해성 멀칭필름의 내가수분해성과 기계적 물성을 향상시키기 위하여 수행되었다. 어닐링 온도조건에 따른 다양한 비율의 사슬연장제와 기계적 물성을 검토하였다. 어닐링공정은 컴파운드 수지의 결정화 능력을 향상시킬수 있음을 나타내었다. 사슬연장제의 첨가로 인장강도를 향상시킬 수 있었으며, 필름의 내가수분해성도 증가하였다. 사슬연장제 0.6phr. 첨가의 경우에 인장강도는 383.0Kgf/cm²으로 대조 필름과 비교하여 155% 향상되었다. 팽창비(BUR)가 2.5일 때, 필름의 최적 인장강도는 기계 방향(MD)과 가로 방향(TD) 에서 379.0/195.2kgf/cm²까지 크게 증가하였다.

• 공업화학
• /
• 제5권4호
• /
• pp.681-697
• /
• 1994

어피로부터 추출한 젤라틴을 효소로 가수분해시킨 가수분해물을 분자량 크기에 따라 분획하여 이를 기능성 소재로서 이용할 목적으로 연속식 3단계 막(1st-SMR, MWCO 10,000; 2nd-SMR, MWCO 5,000; 3rd-SMR, MWCO 1,000) 반응기 장치를 이용하여 젤라틴 가수분해 최적조건이 구명되었고, 또한 막반응기 장치를 장시간 작동하였을 때, 기계적인 응력과 막에 의한 효소활성 및 안정성에 미치는 인자, 그리고 분자량이 서로 다른 가수분해물 획분의 생산량을 높이기 위한 최적화 공정에 대하여 검토하였다. 재순환 3단계 막반응기 장치에서 pH-drop법으로 선정하여 사용한 효소는 Alcalase(1단계), pronate E(2단계)였으며, 3단계에서는 collagenase(3단계)를 사용하였다. 최적 가수분해조건은 1단계의 경우, 효소농도 0.2mg/ml, 기질대 효소비 50(w/w), 온도 $50^{\circ}C$, pH 8.0, 반응부피 600ml 및 유출속도 6.14ml/min였으며, 2단계는 효소농도 0.3mg/ml, 기질대 효소비 33(w/w), 그외의 조건은 1단계와 동일하였다. 그리고 3단계의 경우는 효소농도 0.1mg/ml, 기질대 효소비 100(w/w) 및 유출속도는 10ml/min이였다. 1단계 막반응기를 1시간 작동하였을 때의 기계적인 전단응력 및 막에 의한 효소활성 저하는 30% 및 15%였으며, 2단계 및 3단계는 각각 14%, 5% 및 18%, 8%였다. 1단계, 2단계 및 3단계 막반응기의 최적 가수분해조건하에서 가수분해도는 각각 3.5%(Kjeldahl방법, 87%), 3.1%(77%) 및 2.7%(70%)였으며, 연속식 3단계 막반응기에서 가수분해물의 최종생산량은 부피대체율 10배에서 효소 mg당 430mg이었다.

• Journal of Microbiology and Biotechnology
• /
• 제6권4호
• /
• pp.238-244
• /
• 1996

$\gamma$-Glutamyl transpeptidase ($\gamma$-GTP; EC 2.3.2.2) present in the culture filtrate of Bacillus sp. KUN-17 was purified 400-fold through a consecutive procedure including organic precipitation and column chromatography. The enzyme has an estimated molecular weight of 70, 000 and consists of hetero-subunits with molecular weights of 42, 000 and 22, 000. In vitro optimal conditions for those transfer and hydrolysis reactions appeared to be pH 7.0 at $50^{\circ}C$ and pH 8.4 at $40^{\circ}C$, respectively. The denatured enzyme recovered most of its $\gamma$-GTP activity by removing detergents such as sodium dodecyl sulfate (SDS) or urea with dialysis. The enzyme showed higher affinities against a number of amino acids as $\gamma$-glutamyl acceptors than glycylglycine in the following order: L-valine, L-methionine, L-glutamic acid or L-as-paragine, L-alanine. Also, it was shown that L-glutamine was the most suitable $\gamma$-glutamyl donor for the transfer reaction among those tested. Amino acids generally inhibited the enzyme activity for the transfer reaction, but not for the hydrolysis reaction.

• 한국수산과학회지
• /
• 제33권1호
• /
• pp.79-85
• /
• 2000

굴 자숙농축액의 AOP에 의한 가수분해조건을 확립하였다. 자숙농축액에 대한 AOP의 작용조건은 $pH 7.0{\~}7.5$와 $50{\~}60{\circ}C$이었다. 그리고 효소 반응에 의한 반응시간에 따른 분해생성물의 양은 4 시간까지는 급격히 증가하였으며, 그 이후에는 완만하게 증가하였다. 굴 자숙액에 대하여 0.128 U의 A. oryzae PF protease를 첨가하여 최적조건에서 8 시간 가수분해시켜 가수분해물의 유리 아미노산을 분석한 결과 유리아미노산은 1.41배 증가하였다. AOP 처리에 의한 자숙액의 향미성분의 변화는 대부분의 alcohol, hydrocarbon, ester 및 함황 물질의 양은 증가한 반면에 aldehyde, ketone 화합물의 양은 감소하였으며, 특히 hydrocarbon 화합물의 증감은 분자량과 다소 관련이 있는 것으로 나타났다.

• Journal of Microbiology and Biotechnology
• /
• 제26권1호
• /
• pp.110-119
• /
• 2016

High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 highthroughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2001년도 추계학술발표대회
• /
• pp.629-632
• /
• 2001

자연계로부터 분리된 FJ1의 환경변수 및 기질 특이성을 본 연구에서 살펴보았는데, 분리 균주 FJ1의 특성은 최적pH, 최적온도는 각각 $6{\sim}7$, $25{\sim}30^{\circ}C$이었다. 또한, 분리균주는 FJ는 Avicel, 섬유소페기물과 같은 결정성 섬유소물질의 분해에 유리함을 알 수 있었다. 본 연구에서는 cellulose의 분해에 관련된 효소를 분비하는 분리균주 FJ1의 환경변수 및 기질 특이성을 조사하였고, 이를 기본으로 하여 배양인자의 조절을 통한 최적의 효소생산 및 생산되어진 효소에 의한 섬유소 페기물(볏짚, 폐지, 음식물 쓰레기 등)의 당화 특성을 검토하고 있다.

• 한국미생물·생명공학회지
• /
• 제2권2호
• /
• pp.95-101
• /
• 1974

Studies on the optimum conditions of acid hydrolysis of sweet potato starch cake and its utilization on the production of Saccharomyces cerevisiae as a carbon source were conducted and the results showed as follows; 1.The highest hydrolysis rate, 62.7 ％ of the reducing sugar based on the weight of the dry matter, was obtained when the starch cake was hydrolyzed with 1.0％ of hydrochloric acid at 2.0 kg/$\textrm{cm}^2$ for 30 minutes. 2. But the yeast grew most favorably on the hydrolyzate obtained by treating the starch cake with 0.5％ of hydrochloric acid at 2.0 kg/$\textrm{cm}^2$ for 10 minutes. Reducing sugar content of hydrolyzate was 51.4％. 3. The optimum pH of the culture medium was 7.0, Cell growth reached to the maximum at 36 hours of cultivation time. 4. According to the vitamin requirement tests, Ca-pantothenate was found to be a promoting factor for the growth of the yeast cells. 5. "Gluten acid hydrolyzate" was most effective to the cell growth when added to the medium at the concentration of 0.1％ as a nitrogen source. 6. Sacch. cerevisiae could assimilate the sugars in the hydrolyzate about 89.1％, and the yields of the yeast cells showed 23.2mg/ml of culture medium.

• Journal of Microbiology and Biotechnology
• /
• 제19권12호
• /
• pp.1565-1568
• /
• 2009

Purified Helicobacter pylori urease displayed a sigmoid curve in the plot of velocity versus [S] at urea concentrations less than 0.1mM. Under conditions where preservatives, glycerol, or polyethylene glycol (PEG) were added to the enzyme reaction, the substrate hydrolysis was consistent with Michaelis-Menten kinetics, with a $K_m$ of $0.21\;{\pm}\;0.06\;mM$ and a $V_{max}$ of $1,200\;{\pm}\;300\;{\mu}mol\;min^{-1}\;mg^{-1}$. However, at saturating substrate concentrations, the kinetic parameters of H. pylori urease were unaffected by the presence of the preservatives, and enzyme catalysis conformed to Michaelis-Menten kinetics. The Hill coefficients of the enzyme-catalyzed urea hydrolysis in the presence and absence of PEG were 1 and 2, respectively. Based on these findings, we suggest that H. pylori urease may exist in aggregated and dissociated forms, each with intact function but differing kinetics that may be of importance in maximizing urea breakdown at varying urea concentrations in vivo.

• Journal of Microbiology and Biotechnology
• /
• 제24권9호
• /
• pp.1245-1253
• /
• 2014

One-step sulfuric acid saccharification of the red alga Pterocladiella capillacea was optimized, and various detoxification methods (neutralization, overliming, and electrodialysis) of the acid hydrolysate were evaluated for fermentation with the thermotolerant yeast Kluyveromyces marxianus. A proximate composition analysis indicated that P. capillacea was rich in carbohydrates. A significant galactose recovery of $81.1{\pm}5%$ was also achieved under the conditions of a 12% (w/v) biomass load, 5% (v/v) sulfuric acid, $121^{\circ}C$, and hydrolysis for 30 min. Among the various detoxification methods, electrodialysis was identified as the most suitable for fermentable sugar recovery and organic acid removal (100% reduction of formic and levulinic acids), even though it failed to reduce the amount of the inhibitor 5-HMF. As a result, K. marxianus fermentation with the electrodialyzed acid hydrolysate of P. capillacea resulted in the best ethanol levels and fermentation efficiency.

• Journal of Microbiology and Biotechnology
• /
• 제20권2호
• /
• pp.332-339
• /
• 2010

The lipase from Mucor racemosus NRRL 3631 was partially purified by fractional precipitation using 60% ammonium sulfate, which resulted in a 8.33-fold purification. The partially purified lipase was then immobilized using different immobilization techniques: physical adsorption, ionic binding, and entrapment. Entrapment in a 4% agar proved to be the most suitable technique (82% yield), as the immobilized lipase was more stable at acidic and alkaline pHs than the free enzyme, plus 100% of the original activity was retained owing to the thermal stability of the immobilized enzyme after heat treatment for 60 min at $45^{\circ}C$. The calculated half-lives (472.5, 433.12, and 268.5 min at 50, 55, and $60^{\circ}C$, respectively) and the activation energy (9.85 kcal/mol) for the immobilized enzyme were higher than those for the free enzyme. Under the selected conditions, the immobilized enzyme had a higher $K_m$ (11.11 mM) and lower $V_{max}$ (105.26 U/mg protein) when compared with the free enzyme (8.33 mM and 125.0 U/mg protein, respectively). The operational stability of the biocatalyst was tested for both the hydrolysis of triglycerides and esterification of fatty acids with glycerol. After 4 cycles, the immobilized lipase retained approximately 50% and 80% of its original activity in the hydrolysis and esterification reactions, respectively.