• 생약학회지
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• 제15권1호
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• pp.39-42
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• 1984

To examine stability and a separate quantitative method of a mixed preparation of lactic acid bacteria, a capsule containing Lactobacillus acidophilus, Lactobacillus bulgaricus and Streptococcus thermophilus was suspended and diluted in sterile water. After the diluted suspension was spread on three media of tryptone glucose extract agar, MRS agar and MRS-sucrose agar, their colonies appeared and were counted. The viable counts exceeded the minimum number of the three bacteria and showed that the mixed preparation was stable at least for 18 months. The results also showed that a separate quantitation of viable cells of the each strain was feasible.

• Journal of Dairy Science and Biotechnology
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• 제37권1호
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• pp.57-68
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• 2019

The effects of yogurt supplementation with enzyme-bioconverted ginseng (EBG), ascorbic acid, and yeast extract on the bacterial counts of Streptococcus thermophilus, Lactobacillus acidophilus LA-5, and Bifidobacterium BB-12 were investigated to develop healthy yogurts with high probiotic counts during storage. In addition, the colors and viscosities of the yogurts were determined. EBG, ascorbic acid, and yeast extract did not affect S. thermophilus counts. EBG and ascorbic acid enhanced the viabilities of L. acidophilus LA-5 and Bifidobacterium BB-12 during storage. Yeast extract improved growth of L. acidophilus LA-5 and Bifidobacterium BB-12 during fermentation. EBG turned the yogurt into brown color. We conclude that supplementation of yogurt with EBG, ascorbic acid, and yeast extract may enhance its health-promoting functions by increasing the viability of probiotics, which can thus promote consumption of the yogurt.

• 미생물과산업
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• 제19권1호
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• pp.8-17
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• 1993

젖산생성균의 .betha.-gal의 생성과 Bif. longum KCTC 3215에 의한 .betha.-gal 생산, 정제 및 특성에 관한 연구와 젖산생성균의 .betha.-gal 유전자의 클로닝 및 대장균에의 발현과 Str.thermophilus SKD 1006의 Lac Z 유전자를 비교 분석하였다.

• 한국축산식품학회지
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• 제36권3호
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• pp.412-420
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• 2016

The objective of this study was to investigate characteristics and functionality of yogurt applied red ginseng extract. Yogurts added with red ginseng extract (0.5, 1, 1.5, and 2%) were produced using Lactobacillus acidophilus and Streptococcus thermophilus and stored at refrigerated temperature. During fermentation, pH was decreased whereas titratable aicidity and viable cell counts of L. acidophilus and S. thermophilus were increased. The composition of yogurt samples was measured on day 1, an increase of red ginseng extract content in yogurt resulted in an increase in lactose, protein, total solids, and ash content, whereas fat and moisture content decreased. The pH value and cell counts of L. acidophilus and S. thermophilus were declined, however titratable acidity was increased during storage period. The antioxidant capacity was measured as diverse methods. During refrigerated storage time, the value of antioxidant effect was decreased, however, yogurt fortified with red ginseng extract had higher capacity than plain yogurt. The antioxidant effect was improved in proportion to concentration of red ginseng extract. These data suggests that red ginseng extract could affect to reduce fermentation time of yogurt and enhance antioxidant capacity.

• 한국축산식품학회지
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• 제36권3호
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• pp.427-434
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• 2016

Benzoic acid is occasionally used as a raw material supplement in food products and is sometimes generated during the fermentation process. In this study, the production of naturally occurring yogurt preservatives was investigated for various starter cultures and incubation temperatures, and considered food regulations. Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus rhamnosus, Lactobacillus casei, Lactobacillus paracasei, Lactobacillus reuteri, Lactobacillus plantarum, Bifidobacterium longum, Bifidobacterium lactis, Bifidobacterium bifidum, Bifidobacterium infantis, and Bifidobacterium breve were used as yogurt starter cultures in commercial starters. Among these strains, L. rhamnosus and L. paracasei showed the highest production of benzoic acid. Therefore, the use of L. rhamnosus, L. paracasei, S. thermophilus, and different incubation temperatures were examined to optimize benzoic acid production. Response surface methodology (RSM) based on a central composite design was performed for various incubation temperatures (35-44℃) and starter culture inoculum ratios (0-0.04%) in a commercial range of dairy fermentation processes. The optimum conditions were 0.04% L. rhamnosus, 0.01% L. paracasei, 0.02% S. thermophilus, and 38.12℃, and the predicted and estimated concentrations of benzoic acid were 13.31 and 13.94 mg/kg, respectively. These conditions maximized naturally occurring benzoic acid production during the yogurt fermentation process, and the observed production levels satisfied regulatory guidelines for benzoic acid in dairy products.

• 한국식품조리과학회지
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• 제23권6호
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• pp.968-976
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• 2007

This experiment was carried out to investigate the effects of spirulina powder on the growth properties of lactic acid bacteria in reconstituted skim milk. The spirulina powder supplemented to S. thermophilus and L acidophilus slightly stimulated lactic acid production. In addition, the growth and acid production of L. bulgaricus were enhanced by the addition of spirulina powder. When the spirulina powder was added to reconstituted skim milk at the level of 1%, the mixed cultures of S. thermophilus and L. bulgaricus showed higher numbers of viable cells and higher acid production than the other cultures. The effects of the addition amounts of spirulina powder (1%, 2% and 3%) to the reconstituted skim milk on the growth properties of the mixed cultures of S. thermophilus and L. bulgaricus were evaluated. The pH of the skim milk with added spirulina powder was lower than that of the control, but the amount of spirulina did not have a significant affect. The titratable acidity increased with the incubation time until 12 hr. The number of viable cells in the skim milk with added spirulina increased according to the amount of spirulina. Thus, the spirulina was effective for the increasing lactic acid bacteria in yoghurt.

• Journal of Microbiology and Biotechnology
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• 제30권5호
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• pp.739-748
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• 2020

In this study, a method of heat adaptation was implemented in an attempt to increase the upper thermal threshold of two Streptococcus thermophilus found in South Korea and identified the alterations in membrane fatty acid composition to adaptive response to heat. In order to develop heat tolerant lactic acid bacteria, heat treatment was continuously applied to bacteria by increasing temperature from 60℃ until the point that no surviving cell was detected. Our results indicated significant increase in heat tolerance of heat-adapted strains compared to the wild type (WT) strains. In particular, the survival ratio of basically low heat-tolerant strain increased even more. In addition, the strains with improved heat tolerance acquired cross protection, which improved their survival ratio in acid, bile salts and osmotic conditions. A relation between heat tolerance and membrane fatty acid composition was identified. As a result of heat adaptation, the ratio of unsaturated to saturated fatty acids (UFA/SFA) and C18:1 relative concentration were decreased. C6:0 in only heat-adapted strains and C22:0 in only the naturally high heat tolerant strain were detected. These results support the hypothesis, that the consequent increase of SFA ratio is a cellular response to environmental stresses such as high temperatures, and it is able to protect the cells from acid, bile salts and osmotic conditions via cross protection. This study demonstrated that the increase in heat tolerance can be utilized as a mean to improve bacterial tolerance against various environmental stresses.

• 한국식품과학회지
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• 제11권3호
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• pp.200-205
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• 1979

인산 염(monosodium phosphate, disodium phosphate, trisodium phosphate, ${\alpha}-polygel$ 및 sodium tripolyphosphate)이 Lactobacillus bulgaricus 단독 배양 및 Lactobacillus bulgari쳐s와 Streptococcus thermophilus의 혼합 배양(혼합비 1:1)에 미치는 영향을 검토하였다. 인산 염은 유산균의 생장을 촉진하였으며 특히 단독 배양의 경우 MSP와 STPP가, 혼합 배양의 경우 MSP와 DSP가 가장 효과적이었다. 산도도 유산균의 증식과 동일한 결과를 보였다. 배양액을 실온에서 저장하는 동안 생균 수의 감소는 인산 염 처리구가 대조구에 비하여 완만하였으며 단독 배양시 특히 DSP와 TSP가 효과적이었고 혼합 배양의 경우 TSP와 ${\alpha}-PG$가 가장 효과적이었다. 혼합 균주를 사용하여 제조된 발효유의 저장 중 안정성은 인산염 처리구가 대조구보다 좋았으며 특히 MSP가 가장 효과적이었다.

• 한국미생물·생명공학회지
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• 제36권3호
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• pp.182-188
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• 2008

내열성 Trehalose synthase를 생산하는 초고온성 균주 HJ6은 일본 Arima 온천수에서 분리하였다. 세포의 길이는 $2{\sim}4\;um$, 직경 0.4 um의 간균으로 생육최적 pH와 온도는 각각 6.5와 $80^{\circ}C$이였다. 분리된 균주의 16s rRNA 염기서열을 분석하고 계통학적으로 분류한 결과, HJ6 균주는 Thermus thermophilus에 속하는 것으로 동정되었다. PCR법을 이용하여 trehalose synthase(TS) 유전자를 클로닝하고 염기서열을 분석한 결과, ORF는 2,898개의 뉴클레오타이드로 구성되고 915개의 아미노산을 암호화하였다. 아마노산 서열을 바탕으로 상동성을 분석한 결과, Thermus caldophilus GK24 유래 TS와 99%, Meiothermus ruber 유래 TS와 83%의 identity를 나타내었다. 이 유전자를 온도감수성 프로모터를 포함하는 pJLA503 벡터를 이용하며 대장군에서 발현하고 정제하여 약 110 kDa 단백질을 얻을 수 있었다. 정제된 효소는 트레할로스 전환활성에 대한 최적 pH가 7.5이고, 최적온도는 $80^{\circ}C$이며, 활성의 반감기는 $90^{\circ}C$에서 40분으로 확인되어 높은 내열성을 가지는 것으로 확인되었다. 본 효소의 트레할로스 최대 전환율은 기질농도 500mM에서 55.7%를 나타내었고, 기질 농도가 증가함에 따라 더불어 증가하였기 때문에 본 효소의 트레할로스 전환율을 기질농도에 의존적인 것으로 생각되었다.

• 한국식품과학회지
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• 제31권3호
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• pp.739-745
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• 1999

대두는 여러 생리활성 물질을 함유하고 있는 가격이 저렴한 양질의 식물성 단백질 공급원이다. 그러나 특유의 대두취와 난소화성으로 인해 소비가 제한되고 있어 이를 극복하기 위한 연구의 일환으로 혼합유산 균주 및 효모첨가에 따른 배양시간대별 당이용성 및 아미노산 변화를 측정하여 대두유내 당류와 아미노산들이 혼합균주에 의해 이용되는 경향과 이에 따른 산생성에 대하여 검토하였다. S. thermophilus와 Sac. uvarum로 발효된 처리구가 pH 4.45, 산도 0.86으로 산생성이 가장 우수하였으며, 대두내 당 이용성을 측정한 결과 L. acidophilus와 S. thermophilus로 발효된 처리구는 대두올리고당의 이용성이 다른 처리구에 비해 낮았고, Sac. uvarum과 혼합발효된 처리구들의 당이용성이 높은 것으로 나타났다. 이러한 결과는 Sac. uvarum과 혼합배양하였을 경우 Sac. uvarum이 생산하는 효소에 의해 대두내 과당류로부터 분해된 단당류를 유산균들이 이용하기 때문인 것으로 생각되며, 각 혼합균주의 아미노산 이용성에 있어서도 Sac. uvarum으로 혼합발효된 처리구가 유산균만을 혼합한 처리구에 비해 지속적인 아미노산 이용효율이 더 높게 나타났으며 이는 유산균과 효모의 서로 다른 단백질가수분해능에 의한 상호 보완작용에 기인한 것으로 생각된다.