• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1112-1121
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• 2018

Jeotgal is a Korean traditional fermented seafood with a high concentration of salt. In this study, we isolated lactic acid bacteria (LAB) from galchi (Trichiurus lepturus, hairtail) and myeolchi (Engraulis japonicas, anchovy) jeotgal on MRS agar and MRS agar containing 5% NaCl (MRS agar+5% NaCl), and identified them by using 16S rRNA gene sequencing and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) as culture-dependent methods. We also performed polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) as a culture-independent method to identify bacterial communities. Five samples of galchi-jeotgal and seven samples of myeolchi-jeotgal were collected from different regions in Korea. A total of 327 and 395 colonies were isolated from the galchi- and myeolchi-jeotgal samples, respectively. 16S rRNA gene sequencing and MALDI-TOF MS revealed that the genus Pediococcus was predominant on MRS agar, and Tetragenococcus halophilus on MRS agar+5% NaCl. PCR-DGGE revealed that T. halophilus, Tetragenococcus muriaticus, and Lactobacillus sakei were predominant in both types of jeotgal. T. halophilus was detected in all samples. Even though the same species were identified by both culture-dependent and -independent methods, many species identified by the culture-dependent methods were not in the bacterial list identified by the culture-independent methods. The distribution of bacteria in galchi-jeotgal was more diverse than in myeolchi-jeotgal. The diverse LAB in galchi- and myeolchi-jeotgals can be further studied as candidates for starter cultures to produce fermented foods.

• The Plant Pathology Journal
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• 제32권6호
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• pp.500-507
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• 2016

Single-molecule real-time (SMRT) sequencing allows identification of methylated DNA bases and methylation patterns/motifs at the genome level. Using SMRT sequencing, diverse bacterial methylomes including those of Helicobacter pylori, Lactobacillus spp., and Escherichia coli have been determined, and previously unreported DNA methylation motifs have been identified. However, the methylomes of Xanthomonas species, which belong to the most important plant pathogenic bacterial genus, have not been documented. Here, we report the methylomes of Xanthomonas axonopodis pv. glycines (Xag) strain 8ra and X. campestris pv. vesicatoria (Xcv) strain 85-10. We identified $N^6$-methyladenine (6mA) and $N^4$-methylcytosine (4mC) modification in both genomes. In addition, we assigned putative DNA methylation motifs including previously unreported methylation motifs via REBASE and MotifMaker, and compared methylation patterns in both species. Although Xag and Xcv belong to the same genus, their methylation patterns were dramatically different. The number of 4mC DNA bases in Xag (66,682) was significantly higher (29 fold) than in Xcv (2,321). In contrast, the number of 6mA DNA bases (4,147) in Xag was comparable to the number in Xcv (5,491). Strikingly, there were no common or shared motifs in the 10 most frequently methylated motifs of both strains, indicating they possess unique species- or strain-specific methylation motifs. Among the 20 most frequent motifs from both strains, for 9 motifs at least 1% of the methylated bases were located in putative promoter regions. Methylome analysis by SMRT sequencing technology is the first step toward understanding the biology and functions of DNA methylation in this genus.

• 한국축산식품학회지
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• 제39권5호
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• pp.804-819
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• 2019

Ezine cheese is a non-starter and long-ripened cheese produced in the Mount of Ida region of Canakkale, Turkey, with a protected designation of origin status. Non-starter lactic acid bacteria (NSLAB) have a substantial effect on the quality and final sensorial characteristics of long-ripened cheeses. The dominance of NSLAB can be attributed to their high tolerance to the hostile environment in cheese during ripening relative to many other microbial groups and to its ability to inhibit undesired microorganisms. These qualities promote the microbiological stability of long-ripened cheeses. In this study, 144 samples were collected from three dairies during the ripening period of Ezine cheese. Physicochemical composition and NSLAB identification analyses were performed using both conventional and molecular methods. According to the results of a 16S rRNA gene sequence analysis, 13 different species belonging to seven genera were identified. Enterococcus faecium (38.42%) and E. faecalis (18.94%) were dominant species during the cheese manufacturing process, surviving 12 months of ripening together with Lactobacillus paracasei (13.68%) and Lb. plantarum (11.05%). The results indicate that NSLAB contributes to the microbiological stability of Ezine cheese over 12 months of ripening. The isolation of NSLAB with antimicrobial activity, potential bacteriocin producers, yielded defined collections of natural NSLAB isolates from Ezine cheese that can be used to generate specific starter cultures for the production of Ezine cheese (PDO).

• 한국식생활문화학회지
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• 제37권1호
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• pp.61-72
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• 2022

This study investigated the minimum salt concentration required for achieving the optimal quality characteristics of sauerkrauts made by adding 0.5, 1.0, 1.5, 2.0, and 2.5% (w/w) of sea salt to cabbage according to the fermentation period. For evaluating the quality characteristics, we measured the microorganisms (lactic acid bacteria, yeast, and coliform group), pH, total acidity, salinity, chromaticity, and hardness every 24 hours. The lactic acid bacteria were identified and analyzed, and acceptance test was carried out on the 4^th day of fermentation. The results showed that the salinity of 0.5, 1.0, 1.5, and 2.0% sauerkrauts on the 4^th day of fermentation was lower than the average salinity of Baechu-Kimchi. The 0.5, 1.0, 1.5, and 2.0% sauerkrauts had significantly higher lactic acid bacteria than the 2.5% sample, and the coliform group was not detected after the 5^th day of fermentation. Among the microbes identified, Weissella cibaria JCM 12495 was found only in domestic sauerkraut, in addition to Lactococcus lactis NCDO 604, Leuconostoc citreum JCM 9698, and Lactobacillus sakei DSM 20017. The results of the acceptance test show that 1.0 and 1.5% sea salt sauerkraut had significantly higher overall acceptance compared to the other samples. In conclusion, sauerkraut with a salt concentration of 1.0 and 1.5% (w/w) had abundant lactic acid bacteria and excellent sensory properties, suggesting that the production of low-salted sauerkraut can be adopted to reduce consumer salt intake in the future.

• 산업식품공학
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• 제21권3호
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• pp.242-248
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• 2017

많은 선행연구에서 젖산균 발효 두유 커드의 우수성이 입증이 되었지만 젖산균으로 발효된 두유 커드의 높은 산도는 관능성을 저해하는 주요 요인으로 작용하여 제품의 개발로 이어지기 쉽지 않았다. 본 실험에서는 두유 커드 발효 시 관능성을 높일 수 있는 젖산균을 김치로부터 분리하여 선별된 균주를 이용한 저산도 두유 커드를 제조하였다. 최종 선별된 젖산균은의 16S rDNA 염기서열 분석을 통하여 Pediococcus inopinatus로 동정되었고 P. inopinatus Y2로 명명하였다. P. inopinatus Y2는 $30^{\circ}C$에서 배양 시 가장 빠르게 대수기에 이르는 것으로 나타났으며 $25^{\circ}C$에서 24 시간 발효 시 10.73 log CFU/mL의 최대 생균수를 보였다. P. inopinatus Y2에 의해 발효된 두유 커드의 관능검사 결과 L. sakei strain No. 383, Leu. mesenteroides strain No. 4395에 의해 발효된 두유 커드보다 전반적인 기호도가 높은 것으로 나타났는데 이러한 결과를 토대로 P. inopinatus Y2로 발효된 두유 커드는 식품 개발에 이용할 수 있을 것이라 사료된다.

• 한국축산식품학회:학술대회논문집
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• 한국축산식품학회 2004년도 정기총회 및 제33차 춘계 학술대회
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• pp.89-119
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• 2004

This study was conducted to isolate lactobacilli having probiotic characteristics to be used as health adjuncts with fermented milk products. Acid tolerant strains were selected in Lactobacilli MRS broth adjusted to pH 4.0 from 80 healthy persons (infants, children and adults). And bile tolerant strains were examined in Lactobacilli MRS broth in which 1.0% bile salt was added. By estimation above characteristics, the strains No. 27, which was isolated from adult feces, was selected and identified as Lactobacillus salivarius subsp. salivarius based on carbohydrate fermentation and 16S rDNA sequencing. It was used as a probiotic strain in fermented milk products. The pH of fermented milk decreased from pH 6.7 to 5.0 and titratable acidity increased from 0.3% to 1.0% by L. salivarius subsp. salivarius (isolation strain 20, 35, and 37), when incubated for 36 h at $37^{\circ}C$. The number of viable cell counts of fermented milk was maximized at this incubation condition. The SDS-PAGE evidenced no significant change of casein but distinct changes of whey protein were observed by isolated L. salivarius subsp. salivarius for titratable acidity being incubated by $0.9{\sim}1.0%$ at $37^{\circ}C$. All of the strains produced 83.43 to 131.96 mM of lactic acid and 5.39 to 26.85 mM of isobutyric acid in fermented products. The in vitro culture experiment was performed to evaluate ability to reduce cholesterol levels and antimicrobial activity in the growth medium. The selected L. salivarius subsp. salivarius reduced $23{\sim}38%$ of cholesterol content in lactobacilli MRS broth during bacterial growth for 24 hours at $37^{\circ}C$. All of the isolated L. salivarius subsp. salivarius had an excellent antibacterial activity with $15{\sim}25$ mm of inhibition zone to E. coli KCTC1039, S. enteritidis KCCM3313, S. typhimurium M-15, and S. typhimurium KCCM40253 when its pH had not been adjusted. Also, all of the isolated L. salivarius subsp. salivarius had partial inhibition zone to E. coli KCTC1039, E. coli KCTC0115 and S. enteritidis KCCM3313 when it had been adjusted to pH 5.7. The selected strains were determined to have resistances of twelve antibiotic. Strains 27 and 35 among the L. salivarius subsp. salivarius showed the highest resistance to the antibiotics. Purified ${\alpha}$-galactosidase was obtained by DEAE-Sephadex A-50 ion exchange chromatography, Mono-Q ion exchange chromatography and HPLC column chromatography from L. salivarius subsp. salivarius 27. The specific activity of the purified enzyme was 8,994 units/mg protein, representing an 17.09 folds purification of the original cell crude extract. The molecular weight of enzyme was identified about 53,000 dalton by 12% SDS-PAGE. Optimal temperature and pH for activity of this enzyme were $40^{\circ}C$ and 7.0 respectively. The enzyme was found to be stable between 25 and $50^{\circ}C$. ${\alpha}$-galactosidase activity was lost rapidly below pH 5.0 and above pH 9.0. This enzyme was liberated galactose from melibiose, raffinose, and stachyose, and also the hydrolysis rate of substrate was compound by HPLC. These results indicated that some of the L. salivarius subsp. salivarius (strain 27 and 35) are considered as effective probiotic strains with a potential for industrial applications, but the further study is needed to establish their use as probiotics in vivo.

• 한국식품영양과학회지
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• 제31권4호
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• pp.583-588
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• 2002

비지로부터 두 균주를 순수분리하여 동정한 결과 Ent. faecium LL과 L. rhmnosus LS로 확인되었다. 분리된 균을 대두 미세분말용액에서 발효정도를 알아보기 위하여 pH, 산도, 생균수 및 유기산 함량을 측정하였다 Ent. faecium LL은 대두미세분말 용액에서 발효시 pH 4.9, 산도 0.38%, 생균수 1.8$\times$$10^{9}$ CFU/$m\ell$로 젖산생성 및 높은 생균수를 나타내었다. L. rhamnosus LS는 대두미세분말 용액에서는 4.6$\times$$10^{8}$ CFU/mL의 생균수를 나타냈지만 젖산의 생성은 매우 미흡하였다. 그러나 대두미세분말 용액에 당을 첨가하거나 skim milk를 첨가할때 산생성이 급격히 증가되었다. 대두미세분말과 skim milk 4 : 1 혼합액에서 Ent. faecium LL과 L. rhamnosus LS에 의한 젖산발효는 37$^{\circ}C$에서 20시간 안에 curd를 형성하였으며, 각각 0.33% 및 0.77%의 산도와 $10^{8}$ ~$10^{9}$ CFU/$m\ell$정도의 생균수를 보였다. HPLC 분석에서 생성된 젖산의 농도는 L. rhamnosus LS가 600 mg%로 Ent. faecium LL의 350 mg%보다 높았다.

• Journal of Dairy Science and Biotechnology
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• 제37권2호
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• pp.115-128
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• 2019

본 연구는 전통 김치로부터 유단백질 분해능과 lactose 분해능을 가지는 유산균을 선발하고, 프로바이오틱 활성을 측정하여 발효유용 스타터로서의 이용가능성을 조사하였다. BCP agar에서 젖산생성력이 우수한 32 colony를 선발한 후 내산성 및 내담즙성 모두에서 90% 이상으로 내성이 우수한 2 colony(KC23, KF26)를 2차로 선발하였다. 이들을 대상으로 API 50CHL 탄수화물 이용성 테스트 및 16S rRNA 염기서열을 분석한 결과, L. plantarum KC23과 L. paracasei KF26으로 동정되었다. 이들 중 lactose와 raffinose를 포함하여 당분해능을 가진 L. plantarum KC23을 최종 선발하고 프로바이오틱 활성을 조사하였다. 우유단백질 분해능을 10% 환원탈지유 배양 중의 유리 tyrosine 함량으로 측정한 결과, 배양 8시간 후에는 $24.1{\mu}g/mL$에서 배양 16시간 후에는 $43.9{\mu}g/mL$로 급격하게 증가되었으며, 또한 clear zone형성 크기를 비교한 결과 12 mm로 상업균주인 L. acidophilus CSLA의 9 mm보다 우수한 특성을 보였다. 온도별 생장특성을 확인한 결과는 $45^{\circ}C$에서 보다 $35^{\circ}C$에서 잘 증식하는 중온균의 특성을 나타내었고, $37^{\circ}C$에서 12시간 동안 배양한 결과 배양 6-10시간 사이에 대수증식기를 보였으며, 배양 12시간 후 생균수는 $8.9{\times}10^8CFU/mL$와 pH 4.25 수준을 나타내었다. 항균활성을 측정한 결과는 5개 병원성균에 대하여 8-13 mm의 clear zone을 형성하여 우수한 저해특성을 보였으며, 그중 Salmonella typhimurium과 Bacillus cereus에 대한 항균활성이 가장 우수하였다. 장내부착능을 측정한 결과는 비교균주인 LGG에 비하여 2.23배의 우수한 결과를 보였으며, 10% 환원탈지유를 이용한 $37^{\circ}C$ 배양에서 젖산생성능을 확인한 결과는 대조군인 L. acidophilus CSLA에 비하여 다소 낮은 경향을 보였지만, 적정산도가 0.74% 수준으로서 저산성 발효유 제조를 위한 스타터로 활용 가능할 것으로 판단되었다.