• 대한환경공학회지
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• 제22권3호
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• pp.587-595
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• 2000

국내 하수처리장에 적용되는 BNR(Biological Nutrients Removal) 공정의 효율저하 원인은 유입원수의 낮은 C/N비와 탄소 (Carbon source) 부족이 가장 큰 것으로 지적되어 왔다. 탄소원의 효율적인 공급을 위해 1차 슬러지 산 발효조(Acid fermenter)를 이용하여 SCFAs(Short-Chain Fatty Acids) 생성을 유도할 수 있다. 본 연구에서는 side-stream의 산 발효조와 조합된 $A_2/O$ 프로세스를 운전하여 영양염류 제거에 미치는 영향을 연구하였다. 그 결과 산 발효조의 최대 SCFAs생성은 중온상의 SRT 4~5일에서 약 3.000mg/L(as COD), 대략 0.10~0.16 mg SCFA(as COD)/mg 1차 슬러지(as COD)로 나타났다. 또한 생성된 SCFAs의 성상비는 Acetic, Propionic, (iso)Butyric 및 (iso)Valeric이 1, 0.7, 0.5 그리고 0.6 순으로 나타났다. BNR공정의 side-stream 산 발효조 적용에 의한 영양염류 제거효율은 크게 증가하는 것으로 나타났다. T-N은 인공하수(R1)의 경우 35% 정도의 낮은 처리효율을 나타냈으나 인공 SCFA 주입(R2) 및 발효산물 투입(R3)의 경우 제거효율 74%, 76%로 크게 향상되는 것으로 나타났다. 또한 Phosphate 는 R1의 경우 45% 의 처리효율을 나타냈으나 R2, R3의 경우 73~74% 정도로 양호한 처리효율을 나타냈다. 이는 발효산물 및 SCFA 주입에 의해 혐기조에서 인의 방출 및 호기조에서 과잉섭취가 잘 이루어졌기 때문으로 R3의 경우 인의 방출율은 $0.34g\;PO_4-P/g$ COD로 기존 연구와 비교해서 유사한 것으로 나타났다.

• Animal Bioscience
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• 제35권11호
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• pp.1698-1710
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• 2022

Objective: Raw potato starch (RPS) is resistant to digestion, escapes absorption, and is metabolized by intestinal microflora in the large intestine and acts as their energy source. In this study, we compared the effect of different concentrations of RPS on the intestinal bacterial community of weaned piglets. Methods: Male weaned piglets (25-days-old, 7.03±0.49 kg) were either fed a corn/soybean-based control diet (CON, n = 6) or two treatment diets supplemented with 5% RPS (RPS5, n = 4) or 10% RPS (RPS10, n = 4) for 20 days and their fecal samples were collected. The day 0 and 20 samples were analyzed using a 16S rRNA gene sequencing technology, followed by total genomic DNA extraction, library construction, and high-throughput sequencing. After statistical analysis, five phyla and 45 genera accounting for over 0.5% of the reads in any of the three groups were further analyzed. Furthermore, short-chain fatty acids (SCFAs) in the day 20 fecal samples were analyzed using gas chromatography. Results: Significant changes were not observed in the bacterial composition at the phylum level even after 20 d post feeding (dpf); however, the abundance of Intestinimonas and Barnesiella decreased in both RPS treatment groups compared to the CON group. Consumption of 5% RPS increased the abundance of Roseburia (p<0.05) and decreased the abundance of Clostridium (p<0.01) and Mediterraneibacter (p< 0.05). In contrast, consumption of 10% RPS increased the abundance of Olsenella (p<0.05) and decreased the abundance of Campylobacter (p<0.05), Kineothrix (p<0.05), Paraprevotella (p<0.05), and Vallitalea (p<0.05). Additionally, acetate (p<0.01), butyrate (p<0.05), valerate (p = 0.01), and total SCFAs (p = 0.01) were upregulated in the RPS5 treatment group Conclusion: Feeding 5% RPS altered bacterial community composition and promoted gut health in weaned piglets. Thus, resistant starch as a feed additive may prevent diarrhea in piglets during weaning.

• 한국식품영양과학회지
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• 제26권2호
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• pp.358-369
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• 1997

우리나라 주요 사망원인중의 하나가 되고 있는 혈관질환의 주된 위험인자로 고콜레스테롤 혈증이 지적되고 있다. 콜레스테롤 저하효과가 있는 식이 인자에는 단백질의 종류, 지방의 종류와 양, 식이섬유, 우유, 칼슘, flavonoid 등이 있다. 특히 수용성 식이 섬유의 콜레스테롤 저하효과는 현저하며 동물실험과 인체실험을 통하여 확인되었다. 혈장 콜레스테롤 저하효과가 현저한 식이섬유에는 psyllium husk, pectin, oat fiber, guar gum, sodium alginate 등이 있으며, 농도에 비례하여 그 효과가 커지는 것은 아닌듯하다. 수용성 식이섬유의 콜레스테롤 저하효과에 대한 정확한 기작은 알려져 있지 않으나 몇 가지 가설이 제시되고 있다. 첫째, 식이섬유가 장에서 점성용액을 형성하여 지질 흡수를 저해함으로써 혈장과 간 콜레스테롤 농도를 낮춘다는 것이며, 둘째, 체내 콜레스테롤이 체외로 배설되는 유일한 경로인 담즙산의 소장흡수를 방해하고 변으로의 배설을 증가시켜 체내 콜레스테롤 pool 크기를 감소시킨다는 것이다. 세째, 대장미생물에 의해 생성된 식이섬유의 발효부산물인 short chain fatty acids가 콜레스테롤의 합성을 저해한다는 것이다. 이외에도 여러 가설들이 제시되고 있으며, 이러한 가설들이 서로 상호 배제적인 것은 아니며, 단독으로 혹은 복합적으로 작용하는 것으로 보인다.

• 한국응용과학기술학회지
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• 제2권1호
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• pp.25-31
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• 1985

인유, 조제 분유 및 시유의 트리글리세리드의 구조를 비교하기 위하여 트리글리세리드의 지방산 조성, 아실 탄소수 및 종을 박충 크로마토그래피 및 가스 크로마토그래피를 사용하여 분석하였다. 인유에서는 단쇄 지방산이 검출되지 않은 반면 조세 분유와 시유에서는 1% 미만의 수준들로 검출되었다. 인유에 비하여 조세 분유는 8 : 0, 22 : 0, 24 : 0 등이 유의하게 높은 반면 10 : 0, 14 : 0 등의 지방산들은 유의하게 낮았다. 시유는 인유에 비하여 8 : 0, 10 : 0, 18 : 0, 22 : 0, 24 : 0 등이 유의하게 높았고 12 : 0, 20 : 0 등이 유의하게 낮았다. $18 : 2{\omega}6$은 인유가 12.0%, 조제 분유가 15.0%로 서로 비슷한 반면 시유는 3.8%로 가장 낮았다. 탄소수 20개 이상의 ${\omega}6$계 및 ${\omega}3$계 장쇄 고도 불포화 지방산들은 인유에 비하여 조제 분유와 시유에서 유의하게 낮았다. 인유는 아실 탄소수 44-52, 조제 분유는 50-54, 시유는 36-40 을 가진 글리세드가 주종을 이루고 있었다. 조제 분유에서는 아실 탄소수 50과 52, 시유에서는 42만 제외하고 나머지의 탄소수들은 인유의 그것들과 모두 유의한 차이를 보였다. 조제 분유의 saturates 는 인유의 그것에 비하여 2 배 가량 높았을 뿐 기타 종에서는 모두 유의하게 낮았다. 시유에서도 dienes를 제외한 모든 종에서 조제 분유에서와 동일한 경향이 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제18권11호
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• pp.1646-1654
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• 2005

The present study was carried out to develop cholesterol-reduced and gamma linolenic acid (GLA)-added butter and to examine the changes in chemical and sensory properties, and cholesterol lowering effect of GLA addition. The cholesterol removal rate reached 93.2% by $\beta$-cyclodextrin in butter before GLA addition. The thiobarbituric acid value of cholesterol-reduced and GLA-added butter increased slowly up to 4 week and plauteaued thereafter. TBA value was significantly increased with 2% GLA addition, compared with no GLA addition. The production of short-chain free fatty acids (FFA) increased with storage in all treatments. From 4 weeks storage, the amount of short-chain FFA in 2% GLA-added group was significantly higher than those in other groups. Among sensory characteristics, color, greasiness and overall acceptability were mostly affected by GLA addition, however, the rancidity value of 2% GLA addition was significantly different from those of control and GLA-unadded and cholesterol-reduced butter at 0, 6 and 8 week storage. Among groups, no difference was found in texture in all storage periods. The smallest increase of total blood cholesterol in rats was found in the group fed 2% GLA-added and cholesterol-reduced butter for 8 week, compared with that in controls. The present results showed the possibility of cholesterol-reduced and GLA-added butter development without much difference in chemical, rheological and sensory properties, and indicated a slow increase effect on blood total cholesterol in rats.

• Asian-Australasian Journal of Animal Sciences
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• 제19권3호
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• pp.450-458
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• 2006

The present study was carried out to investigate the changes in chemical and sensory properties, and cholesterol lowering effect of evening primrose oil (EPO) addition in cholesterol-reduced Cheddar cheese. The cholesterol removal rate reached 92.07% by ${\beta}$-cyclodextrin in the cheese before EPO addition. The thiobarbituric acid (TBA) value of cholesterol-reduced and EPO-added cheese increased with both ripening time and amount of EPO addition. Addition of 5% EPO resulted in a significant difference in TBA value after 4-week ripening, compared with no addition of EPO. The production of short-chain free fatty acids (FFAs) increased with ripening period in all treatments. From 4 week of ripening, the amounts of short-chain FFA in 3 and 5% EPO-added groups were significantly higher than those in other groups. Among sensory characteristics, rancidity was mostly affected by EPO addition, however, the rancidity value of 1% EPO-added was not significantly different from that of EPO-free and cholesterol-reduced cheese. Also, Cheddar cheese flavor was not profoundly affected by 1% EPO addition in all ripening periods. Total blood cholesterol dramatically decreased from 184.0 to 137.1 mg/dL with 5% EPO-added and cholesterol-reduced cheese following 8 weeks of feeding. The present results indicated that 5% EPO addition resulted in a profound lowering effect on blood total cholesterol with some adverse effects on chemical and sensory properties.

• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1133-1140
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• 2018

Pseudomonas fluorescens KLR101 was found to be capable of producing polyhydroxyalkanoate (PHA) using various sugars and fatty acids with carbon numbers ranging from 2 to 6. The PHA granules consisted mainly of a poly(3-hydroxybutyrate) homopolymer and/or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolymer. Genomic DNA of P. fluorescens was fractionated and cloned into a lambda library, in which a 5.8-kb fragment that hybridized to a heterologous phaC probe from Ralstonia eutropha was identified. In vivo expression in Klebsiella aerogenes KC2671 (pUMS), restriction mapping, Southern hybridization experiments, and sequencing data revealed that PHA biosynthesis by P. fluorescens relied upon a polypeptide encoded by a 1,683-bp non-operonal ORF, which was preceded by a possible -24/-12 promoter and highly similar to DNA sequences of a gene encoding PHA synthase in the genus Pseudomonas. In vivo expression of the putative PHA synthase gene ($phaC_{Pf}$) in a recombinant Escherichia coli strain was investigated by using glucose and decanoate as substrates. E. coli (${phaC_{Pf}}^+$, pUMS) grown in medium containing glucose accumulated PHA granules consisting mainly of 3-hydroxybutyrate, whereas only a trace amount of 3-hydroxydecanoate was detected from an E. coli fadR mutant (${phaC_{Pf}}^+$) grown in medium containing decanoate. In vitro enzymatic assessment experiments showed that 3-hydroxybutyryl-CoA was efficiently used as a substrate of purified $PhaC_{Pf}$, suggesting that the putative PHA synthase of P. fluorescens utilizes mainly short-chain-length PHA precursors as a substrate.

• Asian-Australasian Journal of Animal Sciences
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• 제18권2호
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• pp.267-276
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• 2005

This study was carried out to investigate the effect of phytosterol ester addition on lowering blood cholesterol in cholesterol-reduced Cheddar cheese. For cholesterol removal, separated cream was treated with 10% ${\beta}$-cyclodextrin at 800 rpm, then blended with remaining skim milk and homogenized with 1,000 psi at $70^{\circ}C$. Experimental cheeses were manufactured by five different levels of phytosterol addition. After the cholesterol reduction process by ;${\beta}$-cyclodextrin, the cholesterol removal rate was in the range of 91.0 to 92.1%. Amount of short-chain free fatty acid and free amino acids increased with an increase of phytosterol ester, and those were significantly different from that of control in all ripening periods. All rheological properties also increased with an increase of phytosterol ester during ripening period. In sensory analysis, the scores of rancid, bitterness Cheddar flavor and off-flavor intensities increased significantly, while texture was decreased during ripening in phytosterol ester-added groups. Total blood cholesterol was reduced by 18% when rats were fed Cheddar cheese treated with 8% phytosterol. The present study indicated that phytosterol ester addition resulted in a profound lowering effect of blood with cholesterol-reduced Cheddar cheese.

• Asian-Australasian Journal of Animal Sciences
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• 제11권5호
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• pp.608-619
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• 1998

The small and the large intestine of swine represent the organs that extract nutrients from feedstuffs through digestion and fermentation and that allow their absorption and incorporation into the blood circulation. Special attention is directed towards the small intestine of young pigs since the transition to a solid diet at weaning exerts major impacts on the structural and functional integrity of the small intestine. Dietary factors involved in postweaning changes of gut morphology and biochemistry such as removal of bioactive compounds in sows milk at weaning, anti-nutritional factors in weaner diets, dietary fiber and the role of voluntary feed intake will be elucidated. The microbial function of the large intestine which is carried out by a diverse population of microorganisms is dependent on substrate availability. Short chain fatty acids as main fermentation products contribute to the energy supply of the host but they are also important for the maintenance of the morphological and functional integrity of the epithelium in the colon. As a result of bacterial nitrogen assimilation in the large intestine, nitrogen is shifted from the urinary to the fecal excretion route thus saving metabolic energy to the pig because less ammonia would become available for conversion to urea.

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2024-2033
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• 2015

A gene encoding lipolytic enzyme, lip7-3, was isolated from Bacillus sp. W130-35 isolated from a tidal mud flat. The gene encoded a protein of 215 amino acids with a signal peptide composed of 34 amino acid residues. Lip7-3 belonged to the family I.4 lipase and showed its maximal activity at pH 9.0 and 60℃. Its activity increased in the presence of 30% methanol and, remarkably, increased as well to 154.6% in the presence of Ca²⁺. Lip7-3 preferred p-nitrophenyl octanoate (C8) as a substrate and exhibited broad specificity for short- to long- chain fatty acid esters. Additionally, Lip7-3 showed a low degree of enantioselectivity for an S-enantiomer (e.g., (S)-methyl-3-hydroxy-2-methylpropionate). It efficiently hydrolyzed glyceryl tributyrate, but did not hydrolyze glyceryl trioleate, fish oil, or olive oil. Its substrate specificity and activation by the solvent might offer a merit to the biotechnological enzyme applications like transesterification in the production of biodiesel.