• 한국축산식품학회지
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• 제28권1호
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• pp.82-90
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• 2008

Kefir 분말제품으로부터 점질물 생성에 관여하는 유산균을 분리 동정하였으며, 분리균의 배양 특성을 조사하였다. 국산 산양유 kefir제품으로부터 순수 분리된 우수한 점질 생성특성을 갖는 2개 균주를 형태 및 생리학적 특성과 16S rDNA염기서열을 기초로 분석한 결과, 각 균주는 99% 이상의 상동성으로 Str. salivarius subsp. thermophilus(LFG-1)과 Lc. lactis subsp. lactis(LFG-2)로 동정되었다. Str. salivarius subsp. thermophilus LFG-1의 최적 생장온도는 $40-45^{\circ}C$, 최적온도에서 대수기의 세대시간은 40.6분이었고, $37^{\circ}C$에서 배양 24시간 후 최종 pH는 4.30으로, 상업균주인 Str. thermophilus Body-1의 pH 4.55보다 다소 낮은 경향을 나타내었다. Str. salivarius subsp. thermophilus LFG-1의 단백질 응고력은 상업균주와 같이 높은 응고력을 보였으나, Lc. lactis subsp. lactis(LFG-2)는 낮은 응고력을 보였다. 모든 균주들은 0.3% bile extract 첨가조건에서 22-29%의 내담즙성을 나타내었고, pH 3.0 이하에서는 대부분 사멸하는 약한 내산성을 보였으나 pH 4.5에서는 생장이 양호하여 요구르트와 같은 발효유 제품용 스타터로서 사용 가능성을 보였다.

• 한국축산식품학회지
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• 제40권6호
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• pp.1014-1032
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• 2020

This work aimed to investigate the psychobiotic effects of six bacterial strains on the mind and behavior of male Wistar rats. The probiotic (PRO) group (n=7) were rats pre-treated with antibiotics for 7 days followed by 14-day probiotic administration, antibiotics (ANT) group (n=7) were rats treated with antibiotics for 21 days without probiotics. The control (CON) group (n=7) were rats that received sham treatment for 21 days. The six bacterial strains with probiotic properties were mostly isolated from Thai fermented foods; Pedicoccus pentosaceus WS11, Lactobacillus plantarum SK321, L. fermentum SK324, L. brevis TRBC 3003, Bifidobacterium adolescentis TBRC 7154 and Lactococcus lactis subsp. lactis TBRC 375. The probiotics were freeze-dried into powder (6×10⁹ CFU/5 g) and administered to the PRO group via oral gavage. Behavioral tests were performed. The PRO group displayed significantly reduced anxiety level and increased locomotor function using a marble burying test and open field test, respectively and significantly improved short-term memory performance using a novel object recognition test. Antibiotics significantly reduced microbial counts in rat feces in the ANT group by 100 fold compared to the PRO group. Probiotics significantly enhanced antioxidant enzymatic and non-enzymatic defenses in rat brains as assessed using catalase activity and ferric reducing antioxidant power assay, respectively. Probiotics also showed neuroprotective effects with less pyknotic cells and lower frequency of vacuolization in cerebral cortex. This multi-strain probiotic formulation from Thai fermented foods may offer a potential to develop psychobiotic-rich functional foods to modulate human mind and behaviors.

• 한국축산식품학회지
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• 제23권3호
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• pp.262-268
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• 2003

Locals 케퍼 그레인은 코카서스 지방에서 유래한 전통적인 발효유이며, 주로 젖산균과 효모로 우유를 발효시켜서 만든다. 국내에서 수집한 10종류의 케퍼 그레인 중에서 6종류가 포도송이 형태나 융털, 나뭇잎, 좁쌀, 수건 같은 특징적인 형태를 가지고 있었으며, 젤라틴같이 끈적한 조직감을 나타냈다. 케퍼 그레인에서 우점하는 미생물을 조사하기 위하여 SPC, MRS, Ml7, Rogosa와 APT 한천배지와 petrifilm을 사용하여 일반세균과 효모를 계수하였다. 5종류의 한천배지 중에서 가장 검출률이 좋았던 것은 SPC, MRS와 Rogosa 한천배지였으며, Ml7과 APT 한천배지에서는 균락의 수가 매우 적었는데, 이는 케퍼 그레인에 존재하는 미생물의 종류가 대부분 젖산간균이었기 때문으로 추정되었다. 각 케퍼 그레인당 50여개 정도의 균락을 분리하여 API 50 CHL kit로 동정한 결과 Lactobacillus fermentum과 Lb. brevis가 각각 41∼88%와 2∼54%의 점유율을 나타내는 우점균으로 밝혀졌다. 이 외에 Lactococcus lactis subsp. lactis와 Leuconostoc mesenteroides subsp. mesenteroides가 소수로 검출되었으며, 일반세균은 전체적으로 $10^{8}$ cfu/g 수준이었고, 효모는 $10^{6}$∼$10^{7}$ cfu/g수준이었다. 케퍼 그레인의 효과적인 보존방법을 찾기 위하여 멸균된 10%환원탈지유와 혼합하여 동결건조한 것, 3개월간 냉장보존한 것, 그리고 6개월간 냉동보존한 것, 그리고 케퍼 그레인 자체로 냉동보존한 것을 비교 평가하였다. 그 결과, 냉동보존한 케퍼 그레인의 복원시 산 생성력이 우수하였으나 15개월 냉동건조한 케퍼 그레인이 냉장 또는 냉동보관한 케퍼 그레인에 비하여 산 생성력이 우수하였을 뿐만 아니라 이미와 이취도 거의 없어 가장 좋은 보존방법으로 평가되었다.

• 한국축산식품학회지
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• 제26권3호
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• pp.402-409
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• 2006

Although microorganisms are, in fact, the most diverse and abundant type of organism on Earth, the ecological functions of microbial populations remains poorly understood. A variety of bacteria including marine Vibrios encounter numerous ecological challenges, such as UV light, predation, competition, and seasonal variations in seawater including pH, salinity, nutrient levels, temperature and so forth. In order to survive and proliferate under variable conditions, they have to develop elaborate means of communication to meet the challenges to which they are exposed. In bacteria, a range of biological functions have recently been found to be regulated by a population density-dependent cell-cell signaling mechanism known as quorum-sensing (QS). In other words, bacterial cells sense population density by monitoring the presence of self-produced extracellular autoinducers (AI). N-acylhomoserine lactone (AHL)-dependent quorum-sensing was first discovered in two luminescent marine bacteria, Vibrio fischeri and Vibrio harveyi. The LuxI/R system of V. fischeriis the paradigm of Gram-negative quorum-sensing systems. At high population density, the accumulated signalstrigger the expression of target genes and thereby initiate a new set of biological activities. Several QS systems have been identified so far. Among them, an AHL-dependent QS system has been found to control biofilm formation in several bacterial species, including Pseudomonas aeruginosa, Aeromonas hydrophila, Burkholderia cepacia, and Serratia liquefaciens. Bacterial biofilm is a structured community of bacterial cells enclosed in a self-produced polymeric matrix that adheres to an inert or living surface. Extracellular signal molecules have been implicated in biofilm formation. Agrobacterium tumefaciens strain NT1(traR, tra::lacZ749) and Chromobacterium violaceum strain CV026 are used as biosensors to detect AHL signals. Quorum sensing in lactic acid bacteria involves peptides that are directly sensed by membrane-located histidine kinases, after which the signal is transmitted to an intracellular regulator. In the nisin autoregulation process in Lactococcus lactis, the NisK protein acts as the sensor for nisin, and NisR protein as the response regulator activatingthe transcription of target genes. For control over growth and survival in bacterial communities, various strategies need to be developed by which receptors of the signal molecules are interfered with or the synthesis and release of the molecules is controlled. However, much is still unknown about the metabolic processes involved in such signal transduction and whether or not various foods and food ingredients may affect communication between spoilage or pathogenic bacteria. In five to ten years, we will be able to discover new signal molecules, some of which may have applications in food preservation to inhibit the growth of pathogens on foods.

• Journal of Microbiology and Biotechnology
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• 제26권2호
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• pp.421-431
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• 2016

Recently, poly-γ-glutamic acid synthetase A (pgsA) has been applied to display exogenous proteins on the surface of Lactobacillus casei or Lactococcus lactis, which results in a surface-displayed component of bacteria. However, the ability of carrying genes encoded by plasmids and the expression efficiency of recombinant bacteria can be somewhat affected by the longer gene length of pgsA (1,143 bp); therefore, a truncated gene, pgsA, was generated based on the characteristics of pgsA by computational analysis. Using murine IL-10 as an exogenous gene, recombinant Lactobacillus plantarum was constructed and the capacity of the surface-displayed protein and functional differences between exogenous proteins expressed by these strains were evaluated. Surface expression of IL-10 on both recombinant bacteria with anchorins and the higher expression levels in L. plantarum-pgsA'-IL-10 were confirmed by western blot assay. Most importantly, up-regulation of IL-1β, IL-6, TNF-α, IFN-γ, and the nuclear transcription factor NF-κB p65 in RAW264.7 cells after stimulation with Poly(I:C) or LPS was exacerbated after co-culture with L. plantarum-pgsA. By contrast, IL-10 expressed by these recombinant strains could reduce these factors, and the expression of these factors was associated with recombinant strains that expressed anchorin (especially in L. plantarum-pgsA'-IL-10) and was significantly lower compared with the anchorin-free strains. These findings indicated that exogenous proteins could be successfully displayed on the surface of L. plantarum by pgsA or pgsA', and the expression of recombinant bacteria with pgsA' was superior compared with bacteria with pgsA.

• 한국식품영양과학회지
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• 제38권6호
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• pp.787-794
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• 2009

자작나무 수액을 이용한 유산균 발효에 적합한 균주의 선발 실험을 통하여 선발된 Lactobacillus균을 이용하여 발효시킨 수액을 실온에서 2주일 이상의 장시간 동안 저장한 결과 $10^{7}cfu/mL$ 이상의 유산균수를 유지하며, 유기산의 생성으로 pH 4.0 이하를 유지하였고 일반세균은 검출되지 않았다. 또, 여과하여 제균을 실시할 시의 미네랄성분의 변화와 유산균에 의한 미네랄의 변화를 분석한 결과 손실량이 극히적은 것으로 나왔다. 이것으로 보아 유산균 발효에 의한 저장성 증진의 효능이 입증되었다.

• Journal of Microbiology
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• 제43권4호
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• pp.345-353
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• 2005

The complex ecosystem of intestinal micro flora is estimated to harbor approximately 400 different microbial species, mostly bacteria. However, studies on bacterial colonization have mostly been based on culturing methods, which only detect a small fraction of the whole microbiotic ecosystem of the gut. To clarify the initial acquisition and subsequent colonization of bacteria in an infant within the few days after birth, phylogenetic analysis was performed using 16S rDNA sequences from the DNA iso-lated from feces on the 1st, 3rd, and 6th day. 16S rDNA libraries were constructed with the amplicons of PCR conditions at 30 cycles and $50^{\circ}C$ annealing temperature. Nine independent libraries were produced by the application of three sets of primers (set A, set B, and set C) combined with three fecal samples for day 1, day 3, and day 6 of life. Approximately 220 clones ($76.7\%$) of all 325 isolated clones were characterized as known species, while other 105 clones ($32.3\%$) were characterized as unknown species. The library clone with set A universal primers amplifying 350 bp displayed increased diversity by days. Thus, set A primers were better suited for this type of molecular ecological analysis. On the first day of the life of the infant, Enterobacter, Lactococcus lactis, Leuconostoc citreum, and Streptococcus mitis were present. The largest taxonomic group was L. lactis. On the third day of the life of the infant, Enterobacter, Enterococcus faecalis, Escherichia coli, S. mitis, and Streptococcus salivarius were present. On the sixth day of the life of the infant, Citrobacter, Clostridium difficile, Enterobacter sp., Enterobacter cloacae, and E. coli were present. The largest taxonomic group was E. coli. These results showed that microbiotic diversity changes very rapidly in the few days after birth, and the acquisition of unculturable bacteria expanded rapidly after the third day.

• 한국식품과학회지
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• 제34권3호
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• pp.536-539
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• 2002

본 연구에서는 증자 콩에 증식하여 부패취를 유발하는 오염균인 야생고초균의 생육을 억제하고 정상발효를 유도하기위해 젖산, 과산화수소 등과 항균성 물질인 bacteriocin을 생성하는 유산균으로 1단 발효를 실시한 후 장류용 황국균을 접종하여 2단 발효 후 다시 고초균으로 3단 발효시켜 황국균과 고초균의 protease, peptidase를 효과적으로 사용함으로서 단백질 분해율이 높아 아미노산 생성량이 많은 기호성 높은 고품질의 메주를 제조하였다. 3단 발효법으로 제조된 메주의 수분함량과 pH를 측정한 결과 각각 54.0 %와 pH 7.0였고 제조된 메주를 30일간 20% 염수로 용출하여 총 유리 아미노산함량을 비교한 결과 3단 발효법으로 제조된 메주구가 대조구에 비해 약 $3{\sim}5$배 높게 나타났다. 특히 장류의 맛을 좌우하는 감칠 맛 성분인 glutamic acid와 aspartic acid의 함량은 대조구에 비해 매우 높아 메주를 원료로 제조하는 장류의 품질을 향상시킬 수 있으며 유리아미노산이 용출되는 시간이 대조구보다 짧아 장류 제조시 발효기간을 1/3정도로 단축시킬 수 있다.

• 한방비만학회지
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• 제18권2호
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• pp.106-114
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• 2018

Objectives: We investigated about the microbial properties and changes in the efficacy of the Codonopsis lanceolata (CL) by natural fermentation. Methods: CL was fermented for four weeks in a well-ventilated place with 2.5% salt. pH, total sugar, total polyphenol, and total flavonoid were measured to determine fermentation characteristics according to fermentation period and salt treatment. Polymerase chain reaction denaturing gradient gel electrophoresis and random amplification of polymorphic DNA-polymerase chain reaction were carried out for microbial analysis during fermentation. In addition, HepG2 cell was cultured to check the lipid accumulation through oil red O staining and the glucose uptake was analyzed by measuring the 2-NBDG at C2C12 cell. Results: The pH level and the total sugar decreased with the CL fermentation. Total polyphenol and flavonoid increased after CL fermentation. It was confirmed that Leuconostoc mesenteroides were maintained continuously during fermentation. In the salt treatment CL, there was a sharp increase in Rahnella aquatilis. Lactobacillus plantarum matrix was observed in fermented CL. In addition, Lactococcus lactis, Weissella koreensis, R. aquatilis, L. plantarum, Leu. mesenteroides have been added to the salt treatment. Glucose uptake were significantly increased after fermentation with salt for four weeks. Lipid accumulation in the HepG2 cells was observed that there was difference (P<0.01) between free fatty acid group (100%) and decreased 4 weeks after fermentation (90.38%) at $800{\mu}g/mL$. Conclusions: Total polyphenol and flavonoid were increased after CL fermentation. Especially, percentage of the glucose uptake and lipid accumulation inhibition increased in CL fermentation with salt. It is expected that fermentation of salt treated CL will be more effective in diabetes and fatty liver.

• 융합정보논문지
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• 제11권4호
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• pp.111-121
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• 2021

감국의 유산균 발효를 통한 감국 배양물(CILL)의 비만억제 식품의 소재로서 가능성을 알아보기 위해 고지방식이로 유도된 C57BL/6 mice에서의 체중, body fat mass, T cell 등을 측정하였다. 체중 변화에서 CILL 군 (25.15±2.44 g)은 4주부터 체중 감소를 보였으며, 1주차부터 8주차까지 낮은 증체량을 유지했다(1.00±0.53 g). 8주 체중(30.38±4.17 g)은 HFD 군(60% high fat diet, 34.99±2.09 g) 대비 13.15%의 체중 감소를 보였다. Fat mass는 10.3022±2.8813 g로 감소했으며, 간 절대 중량에서 HFD 군에 비해 감소하였다. CD4+ T cell 4.84±1.33%, CD8+ T cell 7.02±2.26%, CD4+CD8+ T cell 1.46±0.81%로 HFD 군에 비해 높게 측정되었다. 결과적으로 CILL은 비만억제 효과가 있으며, CILL내의 비만억제 물질을 선별한다면 효과적인 비만억제 식품 소재로서의 가능성이 있을 것으로 사료된다.