Lactic acid bacteria prevent the contamination of food products by inhibiting proliferation of pathogenic bacteria. This is done mainly by the production of lactic acid and antimicrobial peptides (AMP_S) known as bacteriocins. The interest in these molecules resides in both their antimicrobial spectrum and safety for human health. The application of bacteriocins or producer strains has been considered to avoid the development of pathogenic bacteria, as most bacteriocins have significant inhibitory activity against food pathogens, such as Listeria monocytogenes. This article describes the classification, structure, mode of action, biosynthesis, and main applications of bacteriocins in different fields: agri-food, aquaculture, and medicine.

The coronavirus disease 2019 (COVID-19) is a highly contagious pneumonia that has spread throughout the world. It is caused by a novel, single stranded RNA virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Genetic analysis revealed that, phylogenetically, the SARS-CoV-2 is related to severe acute respiratory syndrome-like viruses seen in bats. Because of this, bats are considered as a possible primary reservoir. The World Health Organization has declared the COVID-19 outbreak as a pandemic. As of May 27, 2020, more than 5,406,282 confirmed cases, and 343,562 confirmed deaths have been reported worldwide. Currently, there are no approved vaccines or antiviral drugs available against COVID-19. Newly developed vaccines are in the first stage of clinical trials, and it may take a few months to a few years for their commercialization. At present, remdesivir and chloroquine are the promising drugs for treating COVID-19 patients. In this review, we summarize the diversity, genetic variations, primary reservoirs, epidemiology, clinical manifestations, pathogenesis, diagnosis, treatment strategies, and future prospects with respect to controlling the spread of COVID-19.

Anthocyanins are antioxidant compounds susceptible to environmental factors. Anthocyanin encapsulation into yeast cells is a viable solution to overcome this problem. In this study, the optimal factors for anthocyanin encapsulation were investigated, including anthocyanin concentration, plasmolysis contraction agent, and ethanol concentration, and response surface methodology was evaluated, for the first time. Anthocyanin from Hibiscus sabdariffa L. flowers was encapsulated into Saccharomyces cerevisiae using plasmolysis contraction agent (B: 3%-20% w/v), ethanol concentration (C: 3%-20% v/v), and anthocyanin concentration (A: 0.15-0.45 g/ml). The encapsulation yield and anthocyanin loss rate were determined using a spectrometer (520 nm), and color stability evaluation of the capsules was performed at 80℃ for 30 min. The results of the study showed that these factors have a significant impact on the encapsulation of anthocyanin, in which ethanol agents have the highest encapsulation yield compared to other factors in the study. Statistical analysis shows that the independent variables (A, B, C), their squares (A², B², C²), and the interaction between B and C have a significant effect on the encapsulation yield. The optimized factors were anthocyanin, 0.25 g/ml; NaCl, 9.5% (w/v); and ethanol, 11% (v/v) with an encapsulation yield of 36.56% ± 0.55% and anthocyanin loss rate of 15.15% ± 0.98%; This is consistent with the expected encapsulation yield of 35.46% and loss rate of 13.2%.

Probiotics are live microorganisms that, when administered in adequate amounts, confer health benefits to the host. This study was conducted for the isolation of potential lactic acid bacteria (LAB) with probiotic properties from goat milk and yogurt. Several tests were conducted in vitro using the standard procedures for evaluating the inhibitory spectra of LAB against pathogenic bacteria; tolerance to NaCl, bile salt, and phenol; hemolytic, milk coagulation, and bile salt hydrolase activities; gastrointestinal transit tolerance; adhesion properties; and antibiotic susceptibility. Among 40 LAB strains screened according to culture characteristics, five isolates exhibited antagonistic properties. Three were identified as Pediococcus acidilactici, and two were identified as Enterococcus faecium, exploiting 16S rRNA gene sequencing. All the isolates succeeded in the gastrointestinal transit tolerance assay and successively colonized mucosal epithelial cells. Based on the results of these in vitro assays, both P. acidilactici and E. faecium can be considered as potential probiotic candidates.

Lactobacillus zymae GU240 was previously isolated from Kimchi, a Korean fermented vegetable, as a strong GABA producer. The strain showed β-galactosidase (β-Gal) activity on MRS agar plates with X-gal. When growth and β-Gal activities of GU240 were measured using MRS (glucose, 2%, w/v) and MRSL (lactose, 2%, w/v) broths, cells were found to grow slowly in MRSL, and the β-Gal activity (36 units at 4 h) was lower than that of cells grown in MRS (94 units at 16 h). The highest OD₆₀₀ value of the culture in MRS was 1.6 at 24 h at 37℃, whereas that of the culture in MRSL was 0.6 at 16 h. β-Gal activity of the culture in MRS reached the maximum (95.6 u/ml) at 16 h, decreased thereafter, and was not detected at 48 h. β-Gal activity for culture in MRSL reached its highest (36 u/ml) at 4 h and decreased gradually, but some activity (11.05 u/ml) still remained at 72 h. The structural gene encoding β-Gal in L. zymae GU240 was cloned as a 3.1 kb fragment, and DNA sequencing confirmed the presence of complete lacLM genes. lacLM genes from L. zymae GU240 showed 98-99% homologies in nucleotide sequences with other lacLM genes from L. brevis. Reverse transcription (RT)-PCR confirmed the operon structure of lacLM. The results indicated that L. zymae GU240 might be in the process of losing the ability to grow rapidly on lactose-containing medium, such as milk, due to adaptations to plant environments, including kimchi.

Rapamycin, derived from Streptomyces rapamycinicus, is an important bioactive compound having a therapeutic value in managing Parkinson's disease, rheumatoid arthritis, cancer, and AIDS. Because of its pharmaceutical activity, studies over the past decade have focused on the biosynthesis of rapamycin to enhance its yield. In this study, the effect of rapG on rapamycin production was investigated. The rapG expression vector was constructed by utilizing the integration vector pSET152 under the control of the erythromycin resistance gene (ermE^⁎), a strong constitutive promoter. The rapamycin yield of wild type (WT) and WT/rapG overexpression mutant strains, under fermentation conditions, was analyzed by high-performance liquid chromatography (HPLC). Our results revealed that overexpression of rapG increased rapamycin production by approximately 4.9-fold (211.4 mg/l) in MD1 containing 15 g/l of glycerol, compared to that of the WT strain. It was also found that Illicium verum powder (10 g/l), containing shikimic acid, enhanced rapamycin production in both WT and WT/rapG strains. Moreover, the amount of rapamycin produced by the WT/rapG strain was statistically higher than that produced by the WT strain. In conclusion, the addition 15 g/l glycerol and 15 g/l I. verum powder produced the optimal conditions for rapamycin production by WT and WT/rapG strains.

대표적인 한방 보약 처방인 원방공진단을 재해석한 침향공진단 (당귀, 녹용, 산수유, 및 침향의 혼합추출물)을 유산균으로 발효하고, 침향공진단 성분 중 발효를 통해 증가하는 성분을 분리, 정제하고 nodakenetin임을 동정하였다. 발효 전 침향공진단(침향공진단 농축액 1% 함유 MRS 배지, unfermented Gongjin-dan, GD) 및 발효후 침향공진단(침향공진단 발효액, fermented Gongjin-dan, FGD)에서의 nodakenetin 함량 분석 결과, 각각 6 ㎍/ml과 70 ㎍/ml으로 발효를 통해 nodakenetin이 약 10배 이상 증가하였다. 한편, 고서에 전해지는 공진단의 면역력 강화 효능에 근거하여, GD 및 FGD의 인플루엔자 바이러스 증식 억제 효능을 확인하고자 Neuraminidase (NA) 활성 평가법(NA activity assay)을 실시하였다. 실험 결과, GD는 NA 활성을 억제하지 못하였으나, FGD는 농도의존적으로 NA 활성을 억제하였으며 500 ㎍/ml에서 대조군 대비 약 92%의 억제율을 보였다. 또한, 발효를 통해 증가한 침향공진단의 성분인 nodakenetin과 그 배당체인 nodakenin에 대한 NA 활성 평가 결과, nodakenin은 NA 활성을 거의 억제하지 못하였으나, nodakenetin은 농도의존적으로 NA 활성을 억제하였으며 250 ㎍/ml에서 대조군 대비 약 68%의 억제율을 보였다. 이상의 결과들을 종합하여, 유산균 발효를 통해 침향공진단 내에 미량 존재하던 nodakenetin이 nodakenin의 가수분해로 인해 증가하였으며, NA 활성 억제 성분인 nodakenetin이 증가함으로 인해 FGD도 높은 NA 활성 억제 효능을 보였다고 판단할 수 있었다.

본 연구는 와송에 유기용매를 활용하여 순차적으로 추출하여 항염증 활성에 대한 가능성을 평가하기 하기 위해 수행되었다. 대식세포에 와송 hexane 추출물을 전처리하고 LPS로 염증을 자극하여 염증과 관련한 세포내 신호전달 경로에 미치는 영향을 확인하고자 하였다. 대식세포에 와송 hexane 추출물은 LPS 자극에 의해 세포 독성이 나타나지 않았고, ROS의 생성을 억제하는 것으로 확인되었다. 또한, IL-1β, IL-2, IL-6, IP-10과 같은 전염증성 사이토카인의 분비를 mRNA 수준에서 확인한 결과 탁월하게 억제하였다. 이러한 전염증성 사이토카인의 생성 억제는 상위 전사인자인 AP-1과 IRF3의 조절을 통해 이루어지므로 이들을 단백질 수준에서 발현량을 확인하였다. 그 결과 c-Jun, c-Fos, IRF-3의 인산화 억제로 핵 내 전사활성이 제한되었을 것으로 생각된다. 이들 결과를 종합해볼 때, 와송 hexane 추출물은 염증 반응을 저해하는 효과가 있는 것으로 나타나 다양한 염증성 질환의 예방 및 개선에 유용하게 활용할 수 있을 것으로 생각된다.

송이버섯이 첨가된 전통주를 제조한 후 송절편을 첨가하여 첨가량과 숙성 기간에 따른 향기 성분의 변화를 기체 크로마토그래피 질량분광법을 통해 조사하였다. 송절편을 첨가하지 않은 대조구에서는 총 3종의 향기 성분이 검출되었으나, 송절편을 첨가한 송이주에서는 총 15종의 향기 성분이 검출되었다. 송절편을 5% 첨가한 실험구에서 송이버섯 특유의 향기 성분인 β-fenchyl alcohol과 2-octanol, methyl cinnamate은 숙성기간 동안 상대적인 함량이 증가하여 8주 후에는 각각 67.57%, 2.14%와 0.94%를 나타냈다. 주성분 분석 결과 송절편 첨가에 의한 β-fenchyl alcohol의 상대적 함량 증가가 송이주의 향미 특성에 영향을 미치며, 송이주의 향미 특성은 송절편의 첨가량 보다 숙성 기간에 의해 더 큰 영향을 받는 것으로 판단된다.

Abortive infection systems (Abi) are phage resistance systems that can be prophage-encoded. Here, two genes encoding an Abi system were identified on a prophage sequence contained by the chromosome of the Levilactobacillus brevis strain UCCLBBS124. This Abi system is similar to the two-component AbiL system encoded by Lactococcus lactis biovar. diacetylactis LD10-1. The UCCLBBS124 prophage-derived Abi system (designated here as AbiL₁₂₄) was shown to exhibit specific activity against phages infecting L. brevis and L. lactis strains. Expression of the AbiL₁₂₄ system was shown to cause reduction in the efficiency of plaquing and cell lysis delay for phages of both species.

본 연구에서는 국내 낙동강 수계에서 신규하게 분리된 미세조류인 Parachlorella sp. 종의 바이오매스 및 지방산 생산성에 대한 배지의 영향을 연구하였다. 미세조류 배양에 통상적으로 사용되는 BG-11, TAP, BBM 배지를 사용하여 바이오매스 생산성은 TAP 배지에서, 지방산 축적은 BBM 배지에서 가장 잘 일어나는 것으로 확인되었고, 지방산 생산성을 향상시키기 위해 암모니아와 아세트산을 사용하는 TAP 배지의 조성을 변화하여 BBM 배지처럼 지방산 축적을 유도하며 바이오매스 생산성을 증가시킨 MTAP 배지를 개발하였다. 전체적인 바이오매스와 지방산 생산성을 높이기 위해서는 MTAP-1 배지가 적합하여 바이오매스 생산성과 지방산 생산성은 기존의 TAP 배지 대비 각각 14%, 45% 증가하였다. 생리 활성 효과로 인해 관심도가 높은 오메가-3 지방산의 생산에는 MTAP-4 배지가 가장 적합하여 바이오매스 생산성과 오메가-3 지방산 생산성이 기존 BBM 배지 대비 각각 18%, 39% 증가하여 목표 중점 생산물질(바이오매스, 총 지방산, 또는 오메가-3 지방산)의 생산성을 향상시킬 수 있는 신규 배지 2종의 조성을 개발하였다.

Haematococcus sp.를 대상으로 mixotroph 형태에서 배양을 위한 배지 최적화 연구를 수행하였다. 기본 배지로는 modified MS 배지가 적절했으며, 탄소원으로는 glucose가, 그리고 농도는 10 g/l가 적합하였다. 질소원으로는 KNO₃를 선정하였으며, 농도는 1.9 g/l이 최적이었다. 최적의 배지조건에서 Haematococcus sp.를 초기 접종량(0.18 g/l)로 접종하여 14일 후에 5.58 ± 0.25 g/l로 성장하였으며, 이는 건조 세포중량 기준으로 약 31배의 성장한 것이다. 이때 생성된 클로로필은 172.16 ± 7.79 mg/l였으며, 카로티노이드는 42.33 ± 1.91 mg/l이었다. 본 연구의 결과는 추후 미세조류 대량 배양과 대사산물의 생산에 이용가능한 기초자료가 될 수 있을 것이라 판단된다.

Streptococcus zooepidemicus 유래의 세포외 고분자물질인 히알루론산(hyaluronic acid) (HA)을 대량 생산하기 위해, 균주 개량, 생산배지 및 배양공정 개발에 관한 연구를 수행하였다. HA 고생산성 변이주를 선별하기 위해 약 99%의 사멸률을 보이는 ethylmethane sulfonate (EMS) 처리조건을 적용해서, 지속적인 random screening 방법으로 고생산성, 고안정성의 변이주들을 선별할 수 있었다. HA를 고농도로 생산하기 위해서는, 이 균주의 생화학 및 배양생리적 특성에 기반한 최적 배지개발이 필수적이라고 판단하여, one-factor-at-a-time (OFAT), full factorial design (FFD), steepest ascent method (SAM) 및 response surface method (RSM) (반응표면분석법)을 순차적으로 적용하여 통계적 배지 최적화 실험을 수행하였다. 최적 배지조성에서 플라스크 배양에 의한 HA 생산성은 5.38 g/l로서, 이전 배지(3.54 g/l)에 비해 약 52% 향상된 생산량을 얻을 수 있었다. 또한 선별된 우량균주와 최적화된 생산배지를 이용하여 5 L 발효조에서 배양공정 최적화 연구를 수행하였다. 이 균주의 생리학적 특성을 고려할 때, HA 생산성을 높이기 위해서는 (배양 중 HA 축적으로 인해 고점도를 띠는) 배양액으로의 충분한 용존산소 공급이 매우 중요한 요인인 것으로 판단되었다. 따라서 용존산소 공급과 밀접하게 관련있는 발효조의 교반시스템(교반 날개 종류, 크기 및 배치 등) 및 교반속도에 대한 최적화 연구를 수행하였다. 그 결과, 교반축 하부에는 Rushton turbine-type, 상부에는 marine-type의 확장된 교반날개(기존 대비 직경 1.3배 확장)가 설치된 경우, 450 rpm에서 강화된 혼합력과 충분한 용존산소 공급으로 인해 HA 생산성이 기존 플라스크 배양 대비 약 1.8배(9.79 vs. 5.38 g/l) 더 높은 것으로 확인되었다. 최종적으로 HA 배양공정의 scale-up 가능성을 확인하기 위해, pilot 규모의 50 L 발효조 배양을 최대 300 rpm의 교반속도에서 수행하였다. 처음으로 시도한 50 L 배양임에도 불구하고, HA 최대 생산성 면에서 볼 때, 5 L 발효조 결과와 거의 동일한 수준(98.5%) (9.11 vs 9.25 g/l)의 생산량을 얻을 수 있었다. 반면 지수기 성장단계인 배양 15시간까지의 50 L 배양의 HA 평균생산속도(r_p)는 0.46 g/l/hr로서 0.62 g/l/hr인 5 L 배양 대비 약 74% 정도에 머무는 것으로 나타났다. 따라서 생산 발효조의 scale-up 시, 생산균주의 전단응력 민감성(shear damage)을 함께 고려하면서, 산소전달계수(k_La)를 기반으로 하는 교반시스템에 대한 체계적인 연구가 진행된다면, HA 생산속도도 증가될 수 있는 긍정적인 결과를 얻을 수 있을 것으로 기대된다.

An organic solvent- and bleach-stable protease-producing strain was isolated from a polluted river water sample and identified as Aeromonas veronii OB3 on the basis of biochemical properties (API 20E) and 16S rRNA sequence analysis. The strain was found to hyper-produce alkaline protease when cultivated on fish waste powder-based medium (HVSP, 4080 U/ml). The biochemical properties and compatibility of OB3 with several detergents and additives were studied. Maximum activity was observed at pH 9.0 and 60℃. The crude protease displayed outstanding stability to the investigated surfactants and oxidants, such as Tween 80, Triton X-100, and H₂O₂, and almost 36% residual activity when incubated with 1% SDS. Remarkably, the enzyme demonstrated considerable compatibility with commercial detergents, retaining more than 100% of its activity with Ariel and Tide (1 h, 40℃). Moreover, washing performance of Tide significantly improved by the supplementation of small amounts of OB3 crude protease. These properties suggest the potential use of this alkaline protease as a bio-additive in the detergent industry and other biotechnological processes such as peptide synthesis.

Since, side effects of antibiotics are frequently emphasized these days, their use is gradually diminishing, and alternative drugs are being developed. We have sought to reintroduce them as raw materials for human health as conventional 'weapons' that have been retired after their historical duties. In this study, we investigated the anti-inflammatory effects of lincomycin (LIN), on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Our findings show that LIN potently inhibited production of LPS-induced proinflammatory mediators, such as nitric oxide (NO) and prostaglandin E₂ (PGE₂), without cytotoxicity. Consistent with these findings, LIN strongly decreased protein expression levels of inducible NO synthase (iNOS) and cyclooxygenase (COX-2). Furthermore, LIN reduced pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β. To further elucidate the mechanisms of these inhibitory effects of LIN, we studied LPS-induced IκB-α degradation, and mitogen-activated protein kinase (MAPK) phosphorylation. LIN suppressed downregulation of inhibitory κB (IκB-α) degradation, and the phosphorylation of the c-Jun N-terminal kinase (JNK) pathway. Based on these results, we suggest that LIN may be considered a potential candidate as an anti-inflammatory cosmetic or a medicine for human health.

Candidatus Carsonella ruddii is an endosymbiont that resides in specialized cells within the body cavity of plant sap-feeding insects called psyllids. The establishment of symbiotic associations is considered one of the key factors for the evolutionary success of psyllids, as it may have helped them adapt to imbalanced food resources like plant sap. Although C. ruddii is defined as a psyllid primary symbiont, the genes for some essential amino acid pathways are absent. Complete genome sequences of several C. ruddii strains have been published. However, in-depth intra-species comparison of C. ruddii strains has not yet been done. This study therefore aimed to perform a comparative genome analysis of six C. ruddii strains, allowing the interrogation of phylogenetic group, functional category of genes, and biosynthetic pathway analysis. Accordingly, overall genome size, number of genes, and GC content of C. ruddii strains were reduced. Phylogenetic analysis based on the whole genome proteomes of 30 related bacterial strains revealed that the six C. ruddii strains form a cluster in same clade. Biosynthetic pathway analysis showed that complete sets of genes for biosynthesis of essential amino acids, except tryptophan, are absent in six C. ruddii strains. All genes for tryptophan biosynthesis are present in three C. ruddii strains (BC, BT, and YCCR). It is likely that the host may depend on a secondary symbiont to complement its deficient diet. Overall, it is therefore possible that C. ruddii is being driven to extinction and replacement by new symbionts.

부추 속에 속하는 코끼리마늘(Allium ampeloprasum L.)에 대한 몇 가지 약리효과는 보고된 바 있으나, 이의 항비만 및 작용기전에 대한 보고 전무한 실정이다. 이에 따라, 본 연구에서는 코끼리마늘 추출물이 3T3-L1 지방세포의 분화에 미치는 영향을 조사하여 이의 지방세포 분화 억제 효능을 규명하였다. 본 연구에서는 생코끼리마늘(Raw Elephant Rarlic, REG) 및 흑코끼리마늘(Steam Elephant Garlic, SEG) 추출물이 지방세포의 분화 및 지질축적을 억제한다는 것을 보여주었다. 주목할 만한 점은, REG의 경우 지방세포에 독성을 나타낸 반면, SEG는 독성을 나타내지 않았다는 점이다. 추가적으로, SEG는 PPARγ, C/EBPα, Adiponectin, Ap2 및 LPL와 같은 지방세포 분화 관련 유전자의 발현을 통계적으로 유의하게 억제하였다. 본 연구는 두 종류의 코끼리 마늘이 3T3-L1지방세포의 분화를 억제함을 보고한 최초의 연구이다.

The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) is increasing globally, resulting in high mortality rates. Although CRE is a relatively recent problem in Korea (the first case was not diagnosed until 2010), it is responsible for serious morbidities at an alarming rate. In this study, we carried out a molecular genetic analysis to determine the incidence of CRE and carbapenemase-producing Enterobacteriaceae (CPE) at a general hospital in Korea between August 2017 and August 2019. Forty strains of CPE were isolated from various clinical specimens and analyzed via antimicrobial susceptibility testing, polymerase chain reaction to detect β-lactamase genes, deoxyribonucleic acid sequencing, multilocus sequence typing, curing testing, and conjugal transfer of plasmids. The results demonstrated that all 40 isolates were multidrug-resistant. The fluoroquinolone susceptibility test showed that 75% of the Enterobacteriaceae isolates were resistant to ciprofloxacin, whereas 72.5% were resistant to trimethoprim-sulfamethoxazole. Further, conjugation accounted for 57.5% of all resistant plasmid transfer events, which is 4.3-fold higher than that observed in 2010 by Frost et al. Finally, the high detection rate of transposon Tn4401 was associated with the rapid diffusion and evolution of CPE. Our results highlight the rapid emergence of extensively drugresistant strains in Korea and emphasize the need for employing urgent control measures and protocols at the national level.