Narae Kim

The possible mechanism of rhapontigenin influencing antifungal activity on Candida albicans

Rhapontigenin, an aglycone of rhapontin, was produced by biotransformation and we investigated its antifungal activity against Candida albicans, one of the most important opportunistic fungal pathogens. Rhapontigenin is found to have, in vitro, inhibitory activity with a minimal inhibitory concentration (MIC) value against all test isolates of 128-256 μg/ml. We detected increased reactive oxygen species (ROS) levels in yeast cultures treated with rhapontigenin at the MIC. Rhapontigenin inhibited DNA, RNA, and protein synthesis, especially RNA synthesis, and induced morphological changes and apoptosis of C. albicans. The apoptotic effect of rhapontigenin on C. albicans at subinhibitory concentrations was higher in the stationary growth phase than in the exponential phase, while the opposite results were noted with amphotericin B. The mechanism of antifungal activity of rhapontigenin may be associated with the generation of ROS that might induce apoptosis and it may also involve the inhibition of ergosterol biosynthesis.

Effect of water‐soluble fraction of cherry tomatoes on the adhesion of probiotics and Salmonella to intestinal epithelial cells

BACKGROUND Tomato is one of the most consumed vegetables in the world and contains many valuable nutritional components. Here we investigate the prebiotic effects of cherry tomatoes for improving gut health. RESULTS Water-soluble dietary fiber was prepared from fresh and processed (heat treatment at 80 °C for 15 min) cherry tomato samples, each with and without Viscozyme L treatment. In the adhesion assays, all water-soluble dietary fiber samples improved adhesion of probiotics (Lactobacillus rhamnosus and Bifidobacterium bifidum) to intestinal epithelial cells (Caco-2 cells). Heat treatment in the preparation of juice from cherry tomatoes showed no significant effect on the adhesion of probiotics to Caco-2 cells. The oligofructose content of samples affected the intestinal adhesion of probiotic bacteria, with higher oligosaccharide concentrations associated with greater adhesion of probiotics and more inhibition of the adhesion of pathogens to Caco-2 cells. CONCLUSION The present results suggest that cherry tomato can act as a prebiotic, with oligofructose potentially being one of its major prebiotic components.

Complete Genome Sequence of Mycobacterium bovis Clinical Strain 1595, Isolated from the Laryngopharyngeal Lymph Node of South Korean Cattle

ABSTRACT Mycobacterium bovis strain 1595 was isolated from the lymph node of South Korean native cattle. The complete genome sequence of strain 1595 was determined in 2 contigs and was found to be 4,351,712 bp in size, with a 65.64% G+C content and 4,358 predicted protein-coding genes.

Isolation of Mycobacterium bovis from Free-Ranging Wildlife in South Korea

Abstract We demonstrate Mycobacterium bovis infection in wild boar (Sus scrofa) in South Korea. During 2012–15, we attempted to isolate M. bovis from 847 wild animals, mainly Korean water deer (Hydropotes inermis argyropus), raccoon dogs (Nyctereutes procyonoides), and wild boar, from 11 regions in South Korea. We isolated M. bovis from three of 118 wild boar (2.5%) captured in Gyeonggi Province, where bovine tuberculosis (bTB) outbreaks have also occurred in livestock. Spoligotypes and mycobacterial interspersed repetitive units–variable number tandem repeats types of these M. bovis isolates (SB0140 and SB1040, 4-2-3-3-7-5-5-4-4-3-4-3 and 5-2-3-3-7-5-5-4-3-10-5-2; MIRU4, MIRU16, MIRU27, MIRU31, ETR-A, ETR-B, ETR-C, QUB11b, QUB26, QUB3336, VNTR2401, and VNTR3171) have also been identified from farmed livestock such as cattle (Bos taurus coreanae), Formosan sika deer (Cervus nippon taiouanus), and American elk (Cervus canadensis) in the country. In South Korea, bTB appears to be endemic in livestock, and there are numerous opportunities for contact between wild boar and livestock due to high population densities and broad activity ranges. Our results support the hypothesis that M. bovis is transmitted between domestic and wild animals.

Molecular and genomic features of Mycobacterium bovis strain 1595 isolated from Korean cattle

The aim of this study was to investigate the molecular characteristics and to conduct a comparative genomic analysis of Mycobacterium (M.) bovis strain 1595 isolated from a native Korean cow. Molecular typing showed that M. bovis 1595 has spoligotype SB0140 with mycobacterial interspersed repetitive units-variable number of tandem repeats typing of 4-2-5-3-2-7-5-5-4-3-4-3-4-3, representing the most common type of M. bovis in Korea. The complete genome sequence of strain 1595 was determined by single-molecule real-time technology, which showed a genome of 4351712 bp in size with a 65.64% G + C content and 4358 protein-coding genes. Comparative genomic analysis with the genomes of Mycobacterium tuberculosis complex strains revealed that all genomes are similar in size and G + C content. Phylogenetic analysis revealed all strains were within a 0.1% average nucleotide identity value, and MUMmer analysis illustrated that all genomes showed positive collinearity with strain 1595. A sequence comparison based on BLASTP analysis showed that M. bovis AF2122/97 was the strain with the greatest number of completely matched proteins to M. bovis 1595. This genome sequence analysis will serve as a valuable reference for improving understanding of the virulence and epidemiologic traits among M. bovis isolates in Korea.