A γ-aminobutyric acid (GABA) producing microorganism was isolated from Sun-Tae Jeotgal, a Korean traditional fermented seafood. Two thousand presumptive lactic acid bacteria (LAB) isolates were screened for GABA production by thin layer chromatography. One isolate, T118, produced GABA profusely, and identified as Lactobacillus brevis. Growth of Lb. brevis T118 was examined during 120 h cultivation in MRS broth under different conditions. Lb. brevis T118 grew well at 30-37℃, initial pH of 4-7, and up to 5% NaCl (w/v). A gene, gadB, encoding glutamate decarboxylase (GAD) was cloned by PCR. gadC encoding a glutamate/GABA antiporter was cloned and gadC located immediately upstream of gadB, indicating gadCB operon structure. The operon structure was confirmed by reverse transcription (RT)-PCR. gadB was overexpressed in Escherichia coli BL21 (DE3) and recombinant GAD was purified. The size of recombinant GAD was 54.4 kDa by SDS-PAGE, which matched well with the calculated size from the nucleotide sequence.

Lactic acid bacteria (LAB) were isolated and analysed its fermentation ability in triticale powder at different moisture levels. Furthermore, the antibacterial activity of fermented silage extract against cattle pathogens was also studied. The isolated strains were P. pentosaceus (TC48) and L. brevis (TC50) that confirmed based on biochemical and 16srRNA sequences methods. Extract from LAB fermented silage showed higher antibacterial activity (inhibition zone diameters: 18~24.2 mm) against E. coli P. aeruoginosa, S. aureus and E. Fecalis than the non-inoculated silage extract. TC48 and TC52 strains exhibited high tolerance to artificial gastric, duodenal and intestinal fluids. In summary, lactic acid bacteria mediated fermentation of triticale silage extract showed great antibacterial activity with significant probiotic characteristics might be an effective and safe way to provide new strategies for reducing the incidence of pathogenic bacteria associated diseases in animals.

본 연구에서는 김치로부터 분리된 L. brevis SM61을 생 화학적 특성과 16s rRNA 염기서열 분석을 통해 분리 및 동정하였으며, 흰점박이꽃무지 유충 열수추출물과 산양삼 분말을 L. brevis SM61을 이용하여 48시간동안 발효를 수행하여 발효물을 제조하였다. 그리고, 흰점박이꽃무지 유충 열수추출물과 L. brevis SM61을 사용한 발효물에 대해 농도에 따른 세포 독성은 없는 것으로 판단되었다. 그리고, 흰점박이꽃무지 유충 열수추출물과 L. brevis SM61을 사용한 발효물에 대해 발효 시간에 따른 폴리페놀 함량을 분석한 결과 발효 초기에는 약 1.49 μg/mL 비해 48시간 이후 약 5.09 μg/mL 수준으로 증가하였다. 또한, 항산화능 은 흰점박이꽃무지 유충 열수추출물이 약 60%였으나, L. brevis SM61을 이용한 발효물이 약 98%로 높아졌다. 항균 활성의 경우 L. brevis SM61을 이용한 발효물에서만 항균 효과가 확인되었다. 따라서, 본 연구를 통해 분리된 신규 L. brevis SM61을 이용한 흰점박이꽃무지 유충의 열 수추출물에 대한 발효물은 식용 곤충의 기능성을 강화시 킬 수 있을 것으로 판단되며, 해당 유산균을 활용하여 다양한 식용 곤충에도 적용이 가능할 것으로 사료된다.

Fermented food consists of a variety of lactic acid bacteria (LAB) that are also used in the industry as starter cultures. This genus comprises of different species that find importance as a preservatives in food like meat and sausages. Likewise, Lactobacillus brevis has been recognized as GRAS and is a potential probiotic strain extensively being used on an industrial scale. Since such bacteria are directly related to human health, there has been a need to identify and characterize them on the molecular level. In this study, LAB was identified and characterized from various fermented food samples available in South Korea. Two types to PCR-based molecular typing methods were used to analyze the 13 Lactobacillus brevis isolates, of which one was based on difference in the banding patterns originated on agarose gel and the other was related to the sequence analyses of various housekeeping genes in the particular strain. The former rep-PCR technique used three primers namely, REP, ERIC and (GTG)5 that amplified repetitive sequences in the genome and provided characteristic fingerprint profile for each isolate. This clustered the strains in 3 groups with the help of UPGMA method of clustering distinguishing between closely related strains. However, the latter multilocus sequencing typing (MLST) technique provided definite identification of the strains. A set of 7 housekeeping genes were determined as groEL, gyrB, rpoA, rpoB, pheS, recA and dnaK. These genes were amplified and sequenced and were subjected to comparative analysis. Discrete allelic profiles and 13 sequence types (STs) were resolved and minimum spanning tree (MST) was constructed, revealing the genetic relatedness among the isolates. On comparing the results from both the techniques, MLST proved to generate accurate and precise fingerprints owing to the sequence analysis of conserved genes thus providing a scope for research in the monitoring related species.

The Lactobacillus brevis 340G strain isolated from traditional Korean fermented food (kimchi) produced 15.50mMof γ-aminobutyric acid (GABA) after 48 h of cultivation in MRS media containing 1% L-monosodium glutamate(MSG). The culture conditions of Lb. brevis 340G were optimized for GABA production. Lb. brevis 340G was cul-tivated at 30oC in optimized MRS media containing 3% sucrose and 2% yeast extract with 3% MSG, resulting inmaximum GABA production (68.77mM) after 54 h of cultivation. Skim milk fermented with Lb. brevis 340G pro-duced 4.64mM of GABA in the presence of 1% MSG. These results suggest that Lb. brevis 340G could be usedas a starter for functional fermented foods and skim milk fermented with Lb. brevis 340G could be further devel-oped to become functional dairy food fortified with GABA.

Ginsenosides, ginseng saponin, are the principal components responsible for the pharmacological and biological activities of ginseng. In order to improve absorption and biological activities, the biotransformation of major ginsenoside to minor ginsenoside, as the more active compound, is required. In this study, we isolated Lactobacillus brevis THK-D57, which has high β-glycosidase activity, from Kimchi. The major ginsenoside Rb₁ was converted to the minor ginsenoside ‘compound K’ during the fermentation of L. brevis THK-D57. The results propose that the biotransformation pathway to produce compound K is as follows: ginsenoside Rb₁→ginsenoside Rd→ginsenoside F₂→ginsenoside compound K.

Sourdough 빵을 생산하기 위해 사용되는 유산균중 Lb. brevis는 높은 산 생성율과 단백질 분해 활성과 sourdough 발효 중 발생되는 휘발성 화합물의 합성에 뚜렷하게 기여를 하여 많이 사용되고 있다 따라서 본 실험은 김치에서 분리한 유산균을 sourdough starter로 사용하기 위한 첫 번째 단계로서 Lactobacillus brevis UC-22의 배양 특성 및 최적 성장조건을 조사하였다. 온도에 따른 증식은 35℃에서 배양한 것이 pH의 저하 및 증식이 가장 양호하였으며 이에 병행하여 산 생성량도 균주의 대수 증식기에서 활발하게 분비되는 것을 알 수 있었다. 배지내의 pH에 따른 균의 생장은 pH 5.5와 pH 6.5일 때 증식이 우수하게 나타났다. Lb. brevis의 특정적인 탄소원 이용은 glucose보다는 오히려 maltose를 더 선호하는 경향이 있다고 하였으나 본 실험에서 사용된 Lactobacillus brevis UC-22 는 maltose와 glucose의 첨가에 따른 성장 정도는 큰 차이점을 보이지 않았다.

When used as a starter in the manufacture of Meju, it is expected that the quality of the soup products can be improved. In this study, we isolated Lactobacillus strain having possible safety and food-industrial benefits as a starter. Four hundred and seven isolates were screened from Meju, and chemically characterized for their antibacterial activity against Bacillus cereus, non-productivity of biogenic amine, and hemolysis. Eight of the isolates were selected upon chemical characterization, and their antioxidant and β-glucosidase activity was measured. Finally, we selected, and measured its enzyme activity and antibiotic resistance. Next, we investigated its cell growth, showed maximum biomass of 3.5 g/L after 28 h of culture. The ingredients of the medium to improve biomass were selected using the Plackett-Burman design (PBD) and central composite design (CCD). The results obtained using PBD revealed molasses, yeast extract, and maltose to be significant factors determining the biomass of the L. brevis SCML 432 strain. The CCD was then applied with three variables found from PBD and the optimum values were predicted to be 5.5% molasses, 1.5% yeast extract, and 2.0% maltose, and the maximum biomass was predicted to be 11.2 g/L. Through model verification, we confirmed that the predicted and actual results were similar, with about 3.2-fold improvement in the biomass from 3.5 g/L to 11.3 g/L when compared to that obtained in basal medium. These results suggest that SCML 432 has high potential in the food industry as a starter.

In this study, soy-powder yogurt (SPY) with enhanced levels of γ-aminobutyric acid (GABA) and isoflavone aglycone was produced from sprouting high-protein soybeans (HPSs). The fermented steam-HPS sprouts (0 to 4 cm) were fermented (72 h) with Lactobacillus brevis, and the total free amino acids (FAAs) of the formed mixtures were determined to be 79.53, 489.93, 877.55, 780.53, and 979.97 mg/100 mL in the fermented HPS (FHPS), and the fermented steam-HPS with 0 cm (FSHPS-0), 1 cm (FSHPS-1), 2 cm (FSHPS-2), and 4 cm sprouting lengths (FSHPS-4), respectively. The levels of glutamic acid (GA) and GABA were observed to be the highest, 100.31 and 101.60 mg/100 mL, respectively, in the unfermented HPS (UFSHPS-1, 1 cm) and FSHPS-1 sprouts, respectively. Moreover, the total contents of the isoflavone glycoside form decreased proportionally to the increasing total levels of isoflavone aglycones after fermentation in FSHPS-0, FSHPS-1, FSHPS-2, and FSHPS-4. The levels of isoflavone aglycones were detected as 350.34, 289.15, 361.61, 445.05, and 491.25 μg/g in FHPS, FSHPS-0, FSHPS-1, FSHPS-2, and FSHPS-4, respectively. While FSHPS-1 exhibited the highest DPPH (63.28%) and ABTS (73.28%) radical scavenging activities, FSHPS-4 contained the highest isoflavone aglycone ratio (81.63%). All in all, the FSHPS-1 mixture prepared in this study exhibited high GABA content and functional prosperity, thereby making it suitable for potential applications in the soy-dairy industry.

In the present work we investigated the effects of lactic acid bacteria (LAB) isolated from kimchi on prolifera-tion and apoptosis of cancer cells. The cell-free supernatant concentrate of Lactobacillus brevis OPK-3 significantly retar-ded the proliferation of human acute promyelocytic (HL60), human histiocytic (U937), and mouse lymphocytic (L1210)leukemia cell lines in vitro at concentrations over 2.25-9.0 mg/mL. The treatments of the concentrate leaded to the increasedapoptosis and decreased mitochondrial transmembrane potential in cultured U937 leukemia cell lines. In addition, the treat-ments of the concentrate showed the increased expression of p53 gene in cultured U937 and HL60 leukemia cell lines. Onthe other hand, the cell-free supernatant concentrate of control L. brevis strain (KCCM 41028) showed a relatively littleeffect on the cancer cell proliferation, apoptosis, and mitochondrial transmembrane potential at the similar concentrationranges compared with the L. brevis OPK-3 samples. These results suggest that the consumption of L. brevis OPK-3 could bebeneficial for the inhibitory action on leukemia cell proliferation and for the stimulatory action on the cancer cell apoptosis.