• Journal of Microbiology and Biotechnology
• /
• v.33 no.2
• /
• pp.219-227
• /
• 2023

Lettuce is one of the most consumed vegetables worldwide. However, it has potential risks associated with pathogenic bacterial contamination because it is usually consumed raw. In this study, we investigated the changes in the bacterial community on lettuce (Lactuca sativa L.) in Chungcheong-do, South Korea, and the prevalence of foodborne pathogens on lettuce in different seasons using 16S rRNA gene-based sequencing. Our data revealed that the Shannon diversity index showed the same tendency in term of the number of OTUs, with the index being greatest for summer samples in comparison to other seasons. Moreover, the microbial communities were significantly different between the four seasons. The relative abundance of Actinobacteriota varied according to the season. Family Micrococcaceae was most dominant in all samples except summer, and Rhizobiaceae was predominant in the microbiome of the summer sample. At the genus level, the relative abundance of Bacillus was greatest in spring samples, whereas Pseudomonas was greatest in winter samples. Potential pathogens, such as Staphylococcus and Clostridium, were detected with low relative abundance in all lettuce samples. We also performed metagenome shotgun sequencing analysis on the selected summer and winter samples, which were expected to be contaminated with foodborne pathogens, to support 16S rRNA gene-based sequencing dataset. Moreover, we could detect seasonal biomarkers and microbial association networks of microbiota on lettuce samples. Our results suggest that seasonal characteristics of lettuce microbial communities, which include diverse potential pathogens, can be used as basic data for food safety management to predict and prevent future outbreaks.

• Journal of Ginseng Research
• /
• v.45 no.2
• /
• pp.334-343
• /
• 2021

Background: Gut microbiota mainly function in the biotransformation of primary ginsenosides into bioactive metabolites. Herein, we investigated the effects of three prebiotic fibers by targeting gut microbiota on the metabolism of ginsenoside Rb1 in vivo. Methods: Sprague Dawley rats were administered with ginsenoside Rb1 after a two-week prebiotic intervention of fructooligosaccharide, galactooligosaccharide, and fibersol-2, respectively. Pharmacokinetic analysis of ginsenoside Rb1 and its metabolites was performed, whilst the microbial composition and metabolic function of gut microbiota were examined by 16S rRNA gene amplicon and metagenomic shotgun sequencing. Results: The results showed that peak plasma concentration and area under concentration time curve of ginsenoside Rb1 and its intermediate metabolites, ginsenoside Rd, F2, and compound K (CK), in the prebiotic intervention groups were increased at various degrees compared with those in the control group. Gut microbiota dramatically responded to the prebiotic treatment at both taxonomical and functional levels. The abundance of Prevotella, which possesses potential function to hydrolyze ginsenoside Rb1 into CK, was significantly elevated in the three prebiotic groups (P < 0.05). The gut metagenomic analysis also revealed the functional gene enrichment for terpenoid/polyketide metabolism, glycolysis, gluconeogenesis, propanoate metabolism, etc. Conclusion: These findings imply that prebiotics may selectively promote the proliferation of certain bacterial stains with glycoside hydrolysis capacity, thereby, subsequently improving the biotransformation and bioavailability of primary ginsenosides in vivo.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.364-364
• /
• 2017

Saemangeum reclaimed land is a part of Saemangeum Development Project. Most of the persistent problems of Saemangeum reclaimed land remain to be related to soil salinity. Soil salinity is a major abiotic factor related to microbial community structure and also fungi have been reported to be more sensitive to salinity stress than bacteria. The aim of this study was conducted to investigate the effect of soil salinity levels on the microbial communities in Saemangeum reclaimed land using 454 pyrosequencing analysis. Soil samples was collected from 12 sites of in Saemangeum reclaimed land. For pyrosequencing, 27F/518R (bacteria) and ITS3/ITS4 (fungi) primers were used containing the Roche 454 pyrosequencing adaptor-key-linker (underlined) and unique barcodes (X). Pyrosequencing was performed by Chun's Lab (Seoul, Korea) using the standard shotgun sequencing reagents and a 454 GS FLX Titanium sequencing System (Roche, Inc.). In the soil samples, Proteobacteria (bacteria) and Ascomycota (fungi) shows the highest relative abundance in all the soil sample sites. Proteobacteria, Bacteroidetes, Plantomycetes, Gemmatimonadetes and Parcubacteria were shown to have significantly higher abundance in high salinity level soils than low salinity level soils, while Acidobacteria and Nitrospirae has significantly higher relative abundance in low salinity level soils. The abundance of fungal, Ascomycota has the highest relative abundance in soil samples, followed by Basidiomycota, Chlorophyta, Zygomycota and Chytridiomycota. Basidiomycota, Zygomycota, Glomeromycota and Cerozoa were show significantly higher relative abundance in low salinity level soils. The principal coordinate analysis (PCoA) and correlation analysis shown to salinity-related soil parameters such as ECe, Na+, SAR and EPS were affected to bacterial and fungal community structure. Proteobacteria, Bacteroidetes, Plantomycetes exhibited significantly positive correlation with soil salinity, while Acidobacteria exhibited significantly negative correlation. In the case of fungal community, Basidiomycota and Zygomycota were seen show significantly negative correlation with salinity related soil parameters. These results suggest that provide understanding effect of soil salinity on microbial community structure and correlation of microbial community with soil parameters in Saemangeum reclaimed land.

• Molecules and Cells
• /
• v.23 no.2
• /
• pp.145-153
• /
• 2007

Elucidation of the roles of circadian associated factors requires a better understanding of the molecular mechanisms of circadian rhythms, control of flowering time through photoperiodic pathways, and photosensory signal transduction. In Arabidopsis, the APRR1 quintet, APRRs 1, 3, 5, 7, and 9, are known as central oscillator genes. Other plants may share the molecular mechanism underlying the circadian rhythm. To identify and characterize these circadian response genes in Brassica crops whose genome was triplicated after divergence from Arabidopsis, we identified B. rapa BAC clones containing these genes by BLAST analysis of B. rapa BAC end sequences against the five corresponding Arabidopsis regions. Subsequent fingerprinting, Southern hybridization, and PCR allowed identification of five BAC clones, one for each of the five circadian-related genes. By draft shotgun sequencing of the BAC clones, we identified the complete gene sequences and cloned the five expressed B. rapa circadian-associated gene members, BrPRRs 1, 3, 5, 7, and 9. Phylogenetic analysis revealed that each BrPRR was orthologous to the corresponding APRR at the sequence level. Northern hybridization revealed that the five genes were transcribed at distinct points in the 24 hour period, and Southern hybridization revealed that they are present in 2, 1, 2, 2, and 1 copies, respectively in the B. rapa genome, which was triplicated and then diploidized during the last 15 million years.

• Journal of Life Science
• /
• v.26 no.1
• /
• pp.1-7
• /
• 2016

Fatness is one of the most important economic traits in pigs. The leptin receptor (LEPR) gene may be a potential candidate for the fatness quantitative trait locus (QTL) on porcine chromosome 6, due to its position and physiological role. Thus, this study was carried out to evaluate the associations between structural variants in the LEPR gene and economic traits in pigs. We obtained an approximately 114-kb sequence containing the complete genomic DNA of the porcine LEPR gene, using shotgun sequencing of a bacterial artificial chromosome clone. We report the complete genomic structure of the porcine LEPR gene. Dozens of transcription factor-binding sites were found in the 1.2 kb upstream region from the transcription start point. An association study was performed with 550 Duroc pigs for 24 single-nucleotide polymorphisms (SNPs), including 6 SNPs within exons and 18 SNPs within the putative 5‘ regulatory region of the porcine LEPR gene. Among them, one SNP (−790C/G) was significantly associated with backfat thickness and lean meat percentage, whereas the others, including two SNPs with missense polymorphisms, had no effect on any phenotype. These results suggest that SNP −790C/G may be a useful marker for genetic improvements of fatness and leanness in Duroc pigs.