• 공업화학
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• 제29권4호
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• pp.419-424
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• 2018

무기탄소원으로부터 에탄올을 생산하는 acetogenic 박테리아인 Clostridium ljungdahlii 발효공정에서 배양 배지 조성에 따른 영향을 분석하여 균주 성장과 에탄올 생산 향상을 시도하였다. 균주 성장 및 에탄올 생산에 영향을 줄 수 있는 배지 구성성분으로 yeast extract, fructose, $NH_4Cl$, $K_2HPO_4$를 선정하였다. Yeast extract 농도가 증가할수록 균주 성장과 에탄올 생산이 증가하였으며 에탄올 비생산성은 yeast extract 기본 배지 농도보다 낮은 0.05 g/L에서 가장 높았다. Fructose 농도가 증가할수록 균주 성장은 증가하였지만 5 g/L을 초과하는 fructose 투입은 에탄올 생산을 감소시켰다. Yeast extract 5 g/L인 조건에서 fructose 5 g/L와 넣었을 때 에탄올 생산농도가 0.297 g/L로 가장 높았으나, fructose를 넣지 않았을 때 매우 낮은 균주 농도로 인해 에탄올 비생산성은 0.281 g/g DCW로 높았다. $NH_4Cl$은 균주 성장이나 에탄올 생산은 큰 차이를 보이지 않았으며 30 g/L 이상 과다 투입하면 성장저해가 나타났다. $K_2HPO_4$에 대해서는 농도가 증가할수록 균주 성장과 에탄올 생산이 모두 증가하였다. $NH_4Cl$과 $K_2HPO_4$를 사용한 경우 에탄올 비생산성은 yeast extract를 적게 사용한 경우 크게 나타났다.

• 한국환경보건학회지
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• 제26권2호
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• pp.59-66
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• 2000

Effects of carbon dioxide partial pressure(PCO2) on bacterial population, methane production rate and matter degradation in anaerobic digestion were investigated by using anaerobic chemostat type reactors at 35$\pm$1$^{\circ}C$, at the HRT of 7 days. At PCO2 of 0.5 atm, the specific methane production rate and specific substrate removal rate reached the maximum rates. The methane production rates in the reactors fed by mixed substrate were 26% higher than those obtained under the controlled condition. The number of acetate consuming methanogenic bacteria enumerated by the MPN(most probable number) method, decreased when PCO2 exceeded 0.7 atm. Hydrogen consuming methanogenic bacteria and homoacetogenic bacteria increased as PCO2 increased from 0.1 to 0.6 atm, however, decreased slightly at PCO2 above 0.7 atm. The number of hydrolytic bacteria, sulfate-reducing bacteria and H2-producing acetogenic bacterial were not much influenced by the change of PCO2. The potential methanogenic activity reached the maximum at PCO2 0.5 atm, however, decreased significantly when PCO2 exceeded 0.7 atm, would depend on free PCO2 concentration in solution.

• Journal of Microbiology and Biotechnology
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• 제3권2호
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• pp.108-114
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• 1993

A new strain of acidophilic, acetogenic bacterium, Acetobacter sp. strain HA was isolated by selective enrichment from the traditionally fermented rice wine vinegar in Korea. It was a gram-negative, non-motile short rod and oxidized acetate and lactate. The optimal temperature and pH for growth were $28^{\circ}C$ and 4.0, respectively. The strain HA differed from other Acetobacter species by growing well on methanol, xylitol, inositol, dulcitol, D-xylose, L-arabinose, and D-mannose as sole sources of carbon and energy. The isolated strain HA did not produce $\gamma$-pyrones from glucose and did not produce ketone bodies from glycerol. The quinone system used in this study was an ubiquinone-9 isoprene unit. The guanine-plus-cytosine content of the DNA was 50.7 mol%, and the major cellular fatty acids were $C_{18:1} and C_{16:0}$.

• 자원리싸이클링
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• 제26권1호
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• pp.59-68
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• 2017

본 연구는 항진 항균 작용이 보고되어진 고춧가루 함량(0% ~ 1%)에 따른 음식물쓰레기와 하수슬러지 혼합 물질(1 : 5 V/V%)의 혐기성통합소화 효과를 평가하기 위하여 수행되었다. 본 연구에서 고춧가루 함량 변화가 혐기성미생물 중 가수분해균과 메탄생성균보다 산생성균에 영향을 더 큰 줄 수 있음을 보였으며, 고춧가루함량이 가장 낮은 CAP0 (Capsaicin 0)에서 실험적 누적 메탄수율(ECMY)과 실험적 바이오생산량(EBEP)이 각각 0.17 L $CH_4/g$ $VS_{fed}$와 1,465 cal/g $VS_{fed}$로 최고값으로 측정되어졌다. 그리고 고춧가루 함량이 증가함에 따라 정상운전 위하여 혐기성 미생물의 순응을 위한 기간이 필요함을 보였다.

• 대한환경공학회지
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• 제22권3호
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• pp.417-427
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• 2000

분리막을 침지한 혐기성소화조의 물질분해의 거동과 세균군의 분포 등을 검토하였다. HRT 1.0일과 0.5일의 조건에서 운전하였으며, 온도는 $30^{\circ}C$로 설정하였다. 1.0일 및 0.5일의 HRT에서 탄수화물의 제거율은 각각 99.8~99.9%, 98.0-99.6%를 나타냈다. 1.0일 및 0.5일의 HRT에서 운전개시 후 58일 경과후에는 약 6.050 mg/L, 7,750 mg/L 정도의 MLVSS농도를 나타냈다. 최확수법(MPN)에 의해 각 세균군을 계수한 결과로서 Acidogenic bacteria는 $10^9MPN/mL$ 정도 계수되었고 $H_2$-utilizing methanogenic bacteria 및 Acetalte-utilizing methanogenic bacteria는 각각 $10^7{\sim}10^8$, $10^6{\sim}10^8MPN/mL$ 정도 계수되었으며, $CH_4$의 조성은 46~50%를 나타냈다. Sulfate-reducing bacteria는 $10^7{\sim}10^8MPN/mL$ 정도 계수되었으며, 주로 Acetogenic bacteria의 일원으로 작용하는 것으로 나타났다.

• Environmental Engineering Research
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• 제10권4호
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• pp.181-190
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• 2005

Severe loss or hydrogen occurred in most anaerobic hydrogen fermentation reactors. Several selected methods were applied to suppress the consumption of hydrogen and increase the potential of production. As the first trial, pH shock was applied. The pH of reactor was dropped nearly to 3.0 by stopping alkalinity supply and on]y feeding glucose (5 g/L-d). As the pH was increase to $4.8{\pm}0.2,$ the degradation pathway was derived to solventogenesis resulting in disappearance of hydrogen in the headspace. In the aspect of bacterial community, methanogens weren't detected after 22 and 35 day, respectively. Even though, however, there was no methanogenic bacterium detected with fluorescence in-situ hybridization (FISH) method, hydrogen loss still occurred in the reactor showing a continuous increase of acetate when the pH was increased to $5.5{\pm}0.2$. This result was suggesting the possibility of the survival of spore fanning acetogenic bacteria enduring the severely acidic pH. As an alternative and additive method, nitrate was added in a batch experiment. It resulted in the increase of maximum hydrogen fraction from 29 (blank) to 61 % $(500\;mg\;NO_3/L)$. However, unfortunately, the loss of hydrogen occurred right after the depletion of nitrate by denitrification. In order to prevent the loss entangled with acetate formation, $CO_2$ scavenging in the headspace was applied to the hydrogen fermentation with heat-treated sludge since it was the primer of acetogenesis. As the $CO_2$ scavenging was applied, the maximum fraction of hydrogen was enhanced from 68 % to 87 %. And the loss of hydrogen could be protected effectively.

• 유기물자원화
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• 제19권3호
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• pp.63-72
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• 2011

본 연구에서는 benzalkonium chloride 처리에 따라 바이오가스 생산이 억제되는 정도를 평가하였다. 바이오가스 생산 억제 수준은 10 ppm, 40 ppm, 80ppm의 benzalkonium chloride가 처리되었을 때 각각 10%, 30-40%, 70% 이상이었다. Benzalkonium chloride의 처리에 따라 저해되는 효소를 알아내기 위하여 효소 활성을 분석하였으며 산성/알칼리 포스파타아제, 프로테아제는 메탄 생산량과 음의 상관관계를 나타내었다. ${\alpha}$-글루코시다아제는 실험기간 동안 메탄 생성량과 상대적으로 낮은 음의 상관성을 보였으며(p<0.01, r=-426), 다른 효소와의 상관성도 상대적으로 낮았다. 메탄생성률(ml/day)은 benzalkonium chloride및 산성 포스파타아제와 유의한 상관성을 나타내었다. Benzalkonium chloride가 대장균에 미치는 영향을 원판확산법을 통하여 분석하였다. Benzalkonium chloride의 농도가 높을수록 세균증식 억제대가 확장되었으며, 이를 통하여 benzalkonium chloride가 초산생성균의 증식을 억제함으로써 혐기소화조에 영향을 미칠 수 있다는 것을 확인하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제26권6호
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• pp.856-863
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• 2013

An in vitro gas production technique was used in this study to elucidate the effect of two strains of active live yeast on methane ($CH_4$) production in the large intestinal content of pigs to provide an insight to whether active live yeast could suppress $CH_4$ production in the hindgut of pigs. Treatments used in this study include blank (no substrate and no live yeast cells), control (no live yeast cells) and yeast (YST) supplementation groups (supplemented with live yeast cells, YST1 or YST2). The yeast cultures contained $1.8{\times}10^{10}$ cells per g, which were added at the rates of 0.2 mg and 0.4 mg per ml of the fermented inoculum. Large intestinal contents were collected from 2 Duroc${\times}$Landrace${\times}$Yorkshire pigs, mixed with a phosphate buffer (1:2), and incubated anaerobically at $39^{\circ}C$ for 24 h using 500 mg substrate (dry matter (DM) basis). Total gas and $CH_4$ production decreased (p<0.05) with supplementation of yeast. The methane production reduction potential (MRP) was calculated by assuming net methane concentration for the control as 100%. The MRP of yeast 2 was more than 25%. Compared with the control group, in vitro DM digestibility (IVDMD) and total volatile fatty acids (VFA) concentration increased (p<0.05) in 0.4 mg/ml YST1 and 0.2 mg/ml YST2 supplementation groups. Proportion of propionate, butyrate and valerate increased (p<0.05), but that of acetate decreased (p<0.05), which led to a decreased (p<0.05) acetate: propionate (A: P) ratio in the both YST2 treatments and the 0.4 mg/ml YST 1 supplementation groups. Hydrogen recovery decreased (p<0.05) with yeast supplementation. Quantity of methanogenic archaea per milliliter of inoculum decreased (p<0.05) with yeast supplementation after 24 h of incubation. Our results suggest that live yeast cells suppressed in vitro $CH_4$ production when inoculated into the large intestinal contents of pigs and shifted the fermentation pattern to favor propionate production together with an increased population of acetogenic bacteria, both of which serve as a competitive pathway for the available H2 resulting in the reduction of methanogenic archaea.