This study was designed to examine the immune response in Korean rockfish during water temperature fluctuation and to elucidate the factors contributing to streptococcal pathogenesis in cultured Korean rockfish, S. schlegeli. We investigated cumulative mortality against Streptococcus iniae (FP5228 strain) infection in the exposed Korean rockfish (39.7±5.8 g) to environmentally relevant temperature (Control, 23℃; High temperature, 28℃ and 23℃ and 28℃ with 12 hours interval exchange, 23↔28℃) for 48 hours. Also, the expression of the mRNA related to the immune response genes (heat shock protein 70, interleukin- 1β, lysozyme g-type and thioredoxin-like 1) were measured in spleen and head kidney by real-time PCR analysis in the exposed fish to thermal stress. In this study, the combined stress with bacterial challenge in fishes exposed to thermal stress lowered the survival rate than that of control (23℃). The cumulative mortality in the group of control, 28℃ and 23↔28℃ was 24%, 24% and 40% (P<0.05), respectively. Also, thermal stress modulated the mRNA level of immune related genes; heat shock protein 70, interleukin-1β, lysozyme g-type and thioredoxin-like 1 in Korean rockfish. The present study indicates that a high and sudden water temperature change affect immune responses and reduce the disease resistance in Korean rockfish.

Dental caries is an infectious disease that is caused by the interaction between the host, the diet, and a diverse microbial community. This study illustrated the anticariogenic effects of THYJ-15 against Streptococcus mutans, a major agent of dental caries. THYJ-15 was identified as Latilactobacillus sakei subsp. sakei through 16S rRNA sequencing, with a similarity of 99.72% to L. sakei subsp. sakei JCM 1157T. The cell-free supernatant of L. sakei subsp. sakei THYJ-15 observed MIC values of 10 mg/mL and MBC values of 20 mg/mL against S. mutans KACC 16833T. The cell-free supernatant of L. sakei subsp. sakei THYJ-15 showed significant inhibitory effects on biofilm formation, acid production and glucosyltransferases(GTFs) production against S. mutans. As a results, it was confirmed that L. sakei subsp. sakei THYJ-15 is a lactic acid bacterium possessing notable anticariogenic effects. Accordingly, L. sakei subsp. sakei THYJ-15 is expected to have great potential to be used as a basic substance for dental caries treatment caused by S. mutans.

Dental caries is an infectious disease accompanied by the destruction of teeth. It is a multifactorial disease caused by the interaction between microbes in dental plaque and food, with cariogenic Streptococcus mutans being one of the primary causes. In this study, the antimicrobial and antibiofilm activities of Lactiplantibacillus plantarum THK-j112 isolated from Kimchi, a traditional fermented food, against S. mutans were investigated. Furthermore, this paper also showed the possibility of developing this strain. After analyzing the 16S rRNA sequence, strain THK-j112 was named L. plantarum THK-j112 as it shared 99.93% similarity with L. plantarum ATCC 14917T. Both L. plantarum THK-j112 and L. plantarum ATCC 14917T demonstrated MIC values of 5 mg/mL and MBC values of 10 mg/mL against S. mutans KACC 16833T. The study confirmed that L. plantarum THK-j112 exhibited significant concentration-dependent inhibitory effects on biofilm formation, acid production, and glucosyltransferases(GTFs) production. Regarding hemolytic activity, Bacillus cereus ATCC 14579T, used as a positive control, was confirmed to cause hemolysis, whereas L. plantarum THK-j112 did not cause this phenomenon. Additionally, except for gentamicin, the antibiotic resistance test revealed a lower value than the MIC cut-off value for each antibiotic, indicating no resistance. Based on the findings, L. plantarum THK-j112 is expected to be useful in the food industry, such as functional food, as a lactic acid bacterium with antimicrobial and antibiofilm effects.

Nonalcoholic fatty liver disease (NAFLD) is recognized one of the leading metabolic diseases globally, and the younger age population with the disease is rapidly growing, especially in developed countries. Since there has been no approved medicine, losing weight is known to be the only best remedy to control or reverse the disease. Recently, the field of microbiome has attracted much attention to offer more practical choices for patients. Here, we provide experimental evidence that Streptococcus thermophilus LM1012 (LM1012), a safe probiotic strain, is effective for improving NAFLD indexes. In the methionine-choline deficient (MCD) diet induced C57BL/6 mouse model, administration of LM1012 promoted marked reductions of aspartate transaminase (23.8%), total bilirubin (27.8%), hydroxycholesterol (64.2%), triglyceride (29.7%) and IL-1β (68.3%) compared to the MCD diet alone group. Also, the histopathological data imply that LM1012 inhibited fat accumulation and inflammation in the liver, which are the key biomarkers for progression of the disease. Together, these findings suggest that human consumption of LM1012 as a healthy nutritional supplement, may be helpful in reducing the risk of liver damages in NAFLD patients.

Probiotic strain is known to regulate the immune system by colonizing in the intestine and interact with intestinal cell receptors of lymphoid tissue. In this study, safety of Streptococcus thermophilus KCTC14471BP and silk fibroin coating effects was evaluated with respect to mucin binding abilities and immune system modulation. S. thermophilus KCTC14471BP was coated with silk fibroin by adding 1% water-soluble calcium and 0.1% silk fibroin. S. thermophilus KCTC14471BP showed the high activities of leucine arylamidase and β-galactosidase. Regarding the antibiotic resistance tests, S. thermophilus KCTC14471BP was susceptible to ampicillin, vancomycin, gentamicin, kanamycin, streptomycin, erythromycin, clindamycin, tetracycline, and chloramphenicol. S. thermophilus KCTC14471BP coated with silk fibroin showed the improved mucin binding ability from 16.1% to 71.3% and was confirmed to have no cytotoxicity against RAW 264.7 macrophage. S. thermophilus KCTC14471BP coated with silk fibroin showed dose-dependently significant increases in pro-inflammatory cytokines IL-1β, IL-6, and TNF-α. These results suggested that S. thermophilus KCTC14471BP can be expected as a promising probiotic bacteria for applications to food industries such as fermentation or functional foods.

Streptococcus mutans and Streptococcus sobrinus play important roles in dental caries. Coptis chinensis is a natural product with antimicrobial activity against enterobacteria; however, its effects on oral streptococci are still unknown. Therefore, the effects of C. chinensis on the growth and biofilm formation of the representative cariogenic bacteria S. mutans and S. sobrinus were investigated for the possible use of C. chinensis as an anticaries agent. The C. chinensis extract was diluted with sterile distilled water, and 0.1–2.5% of the extract was used in the experiment. The effects of the C. chinensis extract on the growth and glucan formation of S. mutans and S. sobrinus were measured by viable cell counting and spectrophotometry at 650 nm absorbance, respectively. Crystal violet staining was also carried out to confirm the C. chinensis extract’s inhibitory effect on biofilm formation. The C. chinensis extract significantly inhibited the growth of S. mutans and S. sobrinus at concentrations of ≥ 0.3% as compared with the control group. The viable cell count of colonies decreased by 1.7-fold and 1.2-fold at 2.5% and 1.25%, respectively, compared with the control group. The biofilm formation of S. mutans and S. sobrinus was inhibited by > 20-fold at C. chinensis extract concentrations of ≥ 1.25% as compared with the control group. In summary, the C. chinensis extract inhibited the growth and biofilm and glucan formation of S. mutans and S. sobrinus . Therefore, C. chinensis might be a potential candidate for controlling dental caries.

치아우식증 치료물질을 개발하기 위하여 한국에서 전통적으로 널리 사용되어왔던 20종류의 약용식물로부터 추출물을 분리하였다. 이를 이용하여 치아우식증 원인균인 Streptococcus sobrinus KCOM 1157에 대한 항균 활성을 나타내는 약용식물들을 조사하였다. 감초, 고삼, 황련, 박하, 송절, 부평초 등의 추출물들이 S. sobrinus KCOM 1157에 대해서 항균 활성을 보여주었다. 이 중 송절, 고삼, 황련 등의 천연 물들은 높은 항균 활성을 나타내었다. 이 결과들은 송절, 고삼, 황련의 천연물들이 S. sobrinus 를 포함한 구강질환 세균들에 대한 항우식증 치료제로서의 가능성이 있음을 의미한다.

Streptococcus mutans is one of the important bacteria that forms dental biofilm and cause dental caries. Virulence genes in S. mutans can be classified into the genes involved in bacterial adhesion, extracellular polysaccharide formation, biofilm formation, sugar uptake and metabolism, acid tolerance, and regulation. The genes involved in bacterial adhesion are gbps (gbpA, gbpB, and gbpC) and spaP. The gbp genes encode glucan-binding protein (GBP) A, GBP B, and GBP C. The spaP gene encodes cell surface antigen, SpaP. The genes involved in extracellular polysaccharide formation are gtfs (gtfB , gtfC , and gtfD ) and ftf , which encode glycosyltransferase (GTF) B, GTF C, and GTF D and fructosyltransferase, respectively. The genes involved in biofilm formation are smu630, relA , and comDE. The smu630 gene is important for biofilm formation. The relA and comDE genes contribute to quorumsensing and biofilm formation. The genes involved in sugar uptake and metabolism are eno, ldh , and relA . The eno gene encodes bacterial enolase, which catalyzes the formation of phosphoenolpyruvate. The ldh gene encodes lactic acid dehydrogenase. The relA gene contributes to the regulation of the glucose phosphotransferase system. The genes related to acid tolerance are atpD, aguD, brpA, and relA . The atpD gene encodes F1F0-ATPase, a proton pump that discharges H+ from within the bacterium to the outside. The aguD gene encodes agmatine deiminase system and produces alkali to overcome acid stress. The genes involved in regulation are vicR, brpA, and relA .

수산 양식 산업에서 발생하는 다제내성균에 의한 질병을 통제하기 위해 기존에 사용하던 수산 용 의약품 대신 어류에 사용이 금지된 동물용 의약품 사용이 증가하고 있다. 그 중, 티아물린 은 그람 양성균에 효과적인 항균성을 나타내기 때문에 일부 양식 어가에서 불법적으로 사용 되고 있다. 불법적 사용을 막기 위해서는 티아물린의 수산동물에 대한 연구를 통해 수의사나 수산질병관리사의 처방전에 따라 수산생물의 치료행위가 수반되어야 한다. 연쇄구균에 감염된 강도다리에 대해 티아물린을 5, 10, 15 mg kg-1의 농도로 근육주사 하였으나 치료 효과가 나타 나지 않았고 15, 30 mg kg-1의 농도로 경구투여 하였으나 마찬가지로 치료 효과가 미비하였다. 안전성 확인을 위해 30, 60 mg kg-1의 농도로 근육주사와 경구투여한 경우 항생제의 독성에 의한 폐사가 발생하였고 따라서 연쇄구균에 감염된 강도다리에 티아물린으로 항생제 처리를 하는 것은 부적절하다고 할 수 있다.

Polyphenon 60 refers to the mixture of catechins present in green tea. The aim of this study was to investigate the antimicrobial activities of polyphenon 60 against 4 strains of Streptococcus mutans and 2 strains of Streptococcus sorbrinus, which are the major causative bacteria of dental caries. The minimum bactericidal concentration (MBC) values of polyphenon 60 for S. mutans and S. sobrinus were determined and the effect of biofilm formation inhibition of that was evaluated. The MBC value of polyphenon 60 against the bacterial strains was 2.5 mg/ml except for one particular strain, S. mutans KCOM 1128 for which the value was 1.25 mg/ml. The results of biofilm formation inhibition assay revealed that polyphenon 60 inhibited biofilm formation more than 90% at a concentration of 2.5 mg/ml. It was apparent that polyphenon exhibited biofilm formation inhibition activity along with bactericidal effect against S. mutans and S. sobrinus. Therefore, it is proposed that polyphenon 60 as one of the components of bactericidal agents could be useful in developing oral hygiene products, toothpaste or gargling solution.

It is noted that Streptococcus mutans (S. mutans) triggers dental caries establishment by two major factors: the synthesis of organic acids, which demineralize dental enamel, and the synthesis of glucans, which mediate the attachment of bacteria to the tooth surface. Therefore, it is noted that the development of a more effective, substantial and safe preventive agent that works against dental caries and periodontal disease is required at this time. For this reason, the present study was designed to investigate the effect of croton seed ethanol extracts on the growth, acid production, adhesion, and insoluble glucan synthesis of S. mutans. In this case, the ethanol extract of croton seed showed concentration dependent inhibitory activity against the growth, acid production and adhesion of S. mutans. Especially, it is important to note that it has produced significant inhibition at the concentration of 0.1 and 0.2 mg/ml as compared to the control group. Moreover, these results suggest that the application of croton seed extract may be considered to be a useful method for the prevention of dental caries.

Streptococcus mutans (S. mutans) is one of the most important bacteria in the formation of dental plaque and dental caries. S. mutans adheres to an acquired pellicle formed on the tooth surface, and aggregates with many oral bacteria. It initiates plaque formation by synthesizing glucan from sucrose, which is catalyzed by glucosyltransferases. Propolis is a resinous mixture produced by honeybees, by mixing saliva and beeswax with secretions gathered from wood sap and flower pollen. Bees prevent pathogenic invasions by coating the propolis to the outer and inner surface of the honeycomb. Propolis has traditionally been used for the treatment of allergic rhinitis, asthma and dermatitis. We investigated the inhibitory effects of propolis ethanol extract on biofilm formation and gene expression of S. mutans. The biofilm formation of S. mutans was determined by scanning electron microscopy (SEM) and safranin staining. We observed that the extract of propolis had an inhibitory effect on the formation of S. mutans biofilms at concentrations higher than 0.2 mg/ml. Real-time PCR analysis showed that the gene expression of biofilm formation, such as gbpB, spaP, brpA, relA and vicR of S. mutans, was significantly decreased in a dose dependent manner. The ethanol extract of propolis showed concentration dependent growth inhibition of S. mutans, and significant inhibition of acid production at concentrations of 0.025, 0.05, 0.1 and 0.2 mg/ml, compared to the control group. These results suggest that the ethanol extract of propolis inhibits gene expression related to biofilm formation in S. mutans.