• 한국미생물·생명공학회지
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• 제22권1호
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• pp.7-12
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• 1994

One bacterial strain, that had made the largest inhibition zone at the antagonism assay and also that lost the inhibition activity by the protease treatment, was isolated from raw milk. That strain was identified as Streptococcus salivarius subsp. thermophilus. The specific growht rate of this strain was maximum at 45$\circ $C. However, at this temperature the strain produced no bacteriocin. The bacteriocin activity was quite stable even at high temperature. Moreover, the activity of the vacteriocin was sensitive to proteases. but not to $\alpha $-amylase, DNase I, or RNase.

• Asian-Australasian Journal of Animal Sciences
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• 제5권3호
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• pp.559-561
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• 1992

Three strains each of L. bulgaricus and S. thermophilus isolated from indigenous dahi were examined for their rate of acid production and corresponding pH values in skim milk medium incubated at $40^{\circ}C$. No significant increase in titrable acidity or decrease in pH were recorded from initial period up to 2nd hour in both the strains. Following this period, however, there was a continuous increase in titrable acidity and a decrease in pH value in the milk for all the tested strains. Further it was observed that there was a variation among these strains for their acid production rate. High rate of acid production was recorded for the L. bulgaricus as compared to S. thermophilus. The results further, suggested that efforts should be made to select a proper pair of L. bulgaricus and S. thermophilus according to their rate of acid production, at a particular temperature in order to produce a good quality product.

• Asian-Australasian Journal of Animal Sciences
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• 제17권11호
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• pp.1591-1598
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• 2004

To isolate the $\beta$-galactosidase producing thermophilic bacteria, samples of mud and water were collected from hot springs of avolcanic area near Golden Springs in New Zealand. Among eleven isolated strains, the strain of KNOUC112 produced the highest amounts of $\beta$-galactosidase at 40 h incubation time (0.013 unit). This strain was aerobic, asporogenic bacilli, immobile, gram negative, catalase positive, oxidase positive, and pigment producing. Optimum growth was at 70-72$^{\circ}C$, pH 7.0-7.2, and it could grow in the presence of 3% NaCl. The main fatty acids of cell components were iso-15:0 (30.26%), and iso-17:0 (31.31%). Based on morphological and biochemical properties and fatty acid composition, the strain could be identified as genus Thermus, and finally as Thermus thermophilus by phylogenetic analysis based on 16S rRNA sequence. So the strain is designated as Thermus thermophilus KNOUC112. A gene from Thermus thermophilus KNOUC112 encoding $\beta$-galactosidase was amplified by PCR using redundancy primers prepared based on the structure of $\beta$-galactosidase gene of Thermus sp. A4 and Thermus sp. strain T2, cloned and expressed in E. coli JM109 DE3. The gene of Thermus thermophilus KNOUC112 $\beta$-galactosidase(KNOUC112$\beta$-gal) consisted of a 1,938 bp open reading frame, encoding a protein of 73 kDa that was composed of 645 amino acids. KNOUC112$\beta$-gal was expressed as dimer and trimer in E. coli JM109 (DE3) via pET-5b.

• Journal of Microbiology and Biotechnology
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• 제23권4호
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• pp.459-466
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• 2013

The lactic acid bacterium Streptococcus thermophilus is widely used as a starter culture for the production of dairy products. Whole-genome sequencing is expected to utilize the genetic basis behind the metabolic functioning of lactic acid bacterium (LAB), for development of their use in biotechnological and probiotic applications. We sequenced the whole genome of Streptococcus thermophilus MTCC 5461, the strain isolated from a curd source, by 454 GS-FLX titanium and Ion Torrent PGM. We performed comparative genome analysis using the local BLAST and RDP for 16S rDNA comparison and by the RAST server for functional comparison against the published genome sequence of Streptococcus thermophilus CNRZ 1066. The whole genome size of S. thermophilus MTCC 5461 is of 1.73Mb size with a GC content of 39.3%. Streptococcal virulence-related genes are either inactivated or absent in the strain. The genome possesses coding sequences for features important for a probiotic organism such as adhesion, acid tolerance, bacteriocin production, and lactose utilization, which was found to be conserved among the strains MTCC 5461 and CNRZ 1066. Biochemical analysis revealed the utilization of 17 sugars by the bacterium, where the presence of genes encoding enzymes involved in metabolism for 16 of these 17 sugars were confirmed in the genome. This study supports the facts that the strain MTCC 5461 is nonpathogenic and harbors essential features that can be exploited for its probiotic potential.

• 동아시아식생활학회지
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• 제26권6호
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• pp.491-497
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• 2016

The objective of this research was to determine the fermentation and quality properties of soy yogurt incorporating insoluble components fermented with Streptococcus thermophilus (S. thermophilus) and Lactobacillus bulgaricus (L. bulgaricus) for 24h. Boiled soybeans were ground and reconstituted into equivalent total solids (18%). After soymilk was homogenized with sugar, it was pasteurized in a water bath at $90^{\circ}C$ for 30 min. Two kinds of lactic acid bacteria were inoculated into two types of soymilk after cooling down $40{\sim}45^{\circ}C$ and fermentation at $37^{\circ}C$ for 24h. Titrable acidity, pH, viscosity, sugar content, and number of viable cells were determined in triplicate. Soy yogurt fermented with L. bulgaricus did not reach pH 4.5, where as S. thermophilus was considered good for achieving pH 4.08 and titratable acidity of 2.27% for 24 h. Soy yogurt fermented with S. thermophilus had a higher viscosity and lower sugar contents than that fermented with L. bulgaricusas incubation time increased. Total viable count was $1.80{\times}10^{10}CFU/mL$ on S. thermophilus and $2.16{\times}10^8CFU/mL$ on L. bulgaricus after 24 h at $37^{\circ}C$. However, there was no significant difference in sensory intensities and preference between the two samples. As a result, S. thermophilus was identified as a better culture than L. bulgaricus for the manufacture of soy yogurt incorporating insoluble components.

• 한국축산식품학회지
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• 제29권2호
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• pp.143-150
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• 2009

Kefir 제품으로부터 분리한 Str. thermophilus LFG를 이용하여 산양유 발효유를 제조하고, 이의 다당체를 이용하기 위하여 발효조건 및 다당체의 특성을 조사한 결과는 다음과 같다. 배양온도에 따른 Str. thermophilus LFG로 제조한 발효물의 CEPS 생산성은 저온$(30-35^{\circ}C)$에서 보다 고온$(40-45^{\circ}C)$배양에서 높았으며, 점도는 우유발효물이 산양유 발효물 비하여 다소 높았지만, CEPS의 생성량은 우유 발효물(4.06-4.46g/L)에서 보다 산양유 발효물(4.74-5.30g/L)에서의 생산성이 높았다. 당류에 따른 CEPS생성량은 무첨가구에 비하여 glucose 3% 첨가구가 14-21%, sucrose 3% 첨가구가 4-16% 상승효과를 보였으며, fructose 3%의 경우는 첨가효과가 나타나지 않았다. 우유 발효물 및 산양유 발효물로부터 분리한 상등백과 CEPS의 전자공여능을 확인한 결과 우유 발효물의 상등액과 CEPS가 산양유 발효물의 상등액과 CEPS 보다 유의적으로 높은 전자공여 효과를 나타내었다. 우유 및 산양유 발효물로부터 CEPS를 각각 분리하여 아미노산의 조성을 비교 분석하였을 때 전체적으로 산양유에서 분리한 CEPS에서 비교적 높은 아미노산 함량을 보였다. 산양유 발효물로부터 분리된 crude exopolysaccharide(CEPS)의 탄수화물함량은 37%, 단백질 함량은 63%이었으며, 구성 당을 분석한 결과, glucose 56.45%, galactose 42.35%, fucose 0.27%(w/w)와 amino sugars로는 galactosamine 1.37%, glucosamine 1.09%를 함유하였다.

• 한국식품과학회지
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• 제20권2호
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• pp.140-147
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• 1988

L. bulgaricus FRI025와 S. thermophilus CH1을 Starter로 단독및 혼합 배양하여 요구르트 제조중 이화학적 미생물학적 변화를 비교 검토한결과 단독으로 배양하였을때 보다 혼합 배양하였을때 산생성, 유산균의 성장 등이 증진되었으며 L. bulgaricus FRI025와 S. thermophilus CH1을각각 1:1, 1:2로 혼합 배양하여 요구르트를 제조한 결과 1:1로 혼합 배양한 경우가 더 효과적 이었으며 적정 배양시간은 mild yogurt의 경우 8시간 acid yogurt의 경우 $9{\sim}10$시간으로 추정되었고 배양 9시간째 pH 4.08 산도 1.14% lactose이용율 24.74, 유산균수 $2.5{\times}10^{10}/ml$ 그리고 점도는 2100CP이었다. $4^{\circ}C$에서 7일간 저장후 요구르트의 품질 변화는 pH와 생균수는 감소하였고 산도와 점도는 증가하였다. 고형분 함량 14%인 환원 탈지유에 L. bulgaricus FRI025와 S. thermophilus CH1을 1:1로 혼합한 starter와 시판 호상 요구르트에 사용되는 starter를 사용하여 산도, 유산균 성장, 기호성에 관해 비교한 결과 분리 균주인 bulgaricus FRI025와 S. thermophilus CH1을 사용한 경우가 시판 호상요구르트 starter를 사용한 경우보다 산생성이나 유산균 성장이 양호 하였으며 기호성이 가장 우수하였다.

• 농업과학연구
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• 제21권2호
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• pp.111-121
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• 1994

탈지유배지(脫脂乳培地)에 인삼(人蔘)extract를 0.3~2.4%를 첨가(添加)하고 yoghurt starter의 기본균종(基本菌種)인 Str. thermophilus, L. bulgaricus 및 2균종(菌種) 혼합균주(混合菌株)를 배양(培養), 배양시간(培養時間)에 따른 산생성(酸生成) 및 균증식(菌增殖) 상태(狀態)를 시험(試驗)한 결과(結果)는 다음과 같다. 1. 인삼(人蔘)extract 첨가(添加) 탈지유배지(脫脂乳培地)에 Str. thermophilus 및 L. bulgaricus를 각각(各各) 배양(培養)할 때 12시간(時間)에 Str. thermophilus control구(區)는 1.11%, L. bulgaricus control구(區)는 1.01%의 산도(酸度)를 나타내었으나 인삼(人蔘)extract 첨가구(添加區)에 있어서는 첨가량(添加量)의 증가(增加)에 따라 Str. thermophilus는 1.08~0.61%, L. bulgaricus는 0.99~0.49%의 산도(酸度)를 나타내 산생성(酸生成)이 억제되는 현상(現象)을 나타내었다. 2. 인삼(人蔘)extract 첨가(添加) 탈지유배지(脫脂乳培地)에 Str. thermophilus 및 L. bulgaricus를 배양(培養)할 때 유산균수(乳酸菌數)의 증가(增加) 상태(狀態)는 12시간(時間)에 Str. thermophilus control구(區)가 $5.2{\times}10^8/m{\ell}$, L. bulgaricus control구(區)는 $3.2{\times}10^8/m{\ell}$이었으며 인삼(人蔘)extract첨가구(添加區)에 있어서는 Str. thermophilus가 $3.6{\times}10^8/m{\ell}{\sim}1.3{\times}10^8/m{\ell}$, L. bulgaricus에 있어서는 $2.9{\times}10^8/m{\ell}{\sim}1.4{\times}10^8/m{\ell}$로서 인삼(人蔘)extract의 첨가량(添加量) 증가(增加)에 따라 균증식상태(菌增殖狀態)가 둔화되는 현상(現象)을 나타내었다. 3. Str. thermophilus 및 L. bulgaricus의 혼합균주(混合菌株)를 인삼(人蔘)extract의 첨가(添加) 탈지유배지(脫脂乳培地)에 배양(培養)할 때 control구(區)와 인삼(人蔘)extract 첨가구간(添加區間)에 산생성(酸生成) 및 균증식(菌增殖) 상태(狀態)에 있어 큰 차이(差異)를 나타내지 않았으며 인삼(人蔘)extract 첨가구(添加區)에 딸사서는 오히려 증가(增加)하였다.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2007년도 제48회 학술심포지움 및 추계국제학술대회
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• pp.54.2-54.2
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• 2007

See Full Text

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2007년도 제48회 학술심포지움 및 추계국제학술대회
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• pp.55.1-55.1
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• 2007

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