• Journal of Environmental Health Sciences
• /
• v.42 no.4
• /
• pp.274-279
• /
• 2016

Objectives: We investigated bacterial diversity in the Han River water resource protection area in order to provide basic microbiological information on the drinking water safety of the Seoul metropolitan region. Methods: Samples were collected in the spring and winter, but not during the rainy season. Pyrosequencing, gene amplification, and extraction of nucleic acids were employed in this study. Results: In total, 57 and 48 operational taxonomic units were respectively analyzed in samples collected during spring and winter. Proteobacteria were predominant in all samples. The samples contained phylogenetically diverse bacterial communities, with eleven major phyla and 36 genera. Cyanobacteria were predominant in the spring samples, but not in the winter samples. The predominant species in the samples collected during both seasons belonged to the genus Aquamicrobium and Bradyrhizobium. Moreover, no pathogenic bacteria were detected in the samples. Conclusion: Proteobacteria were predominant in the samples from the Han River water source protection area. Cyanobacteria were more predominant in the spring samples than in the winter samples, but Aquamicrobium and Bradyrhizobium were predominant in both sampling seasons.

• Journal of Environmental Health Sciences
• /
• v.41 no.1
• /
• pp.40-48
• /
• 2015

Objectives: This study aims to understand the concentration, diversity, and antibiotic characteristics of oxytetracycline resistant bacteria present in a surface water environment. Methods: Water sampling was performed in Cheongmi Stream in Gyeonggi-do, Korea in February and August 2014. Water samples collected from two sites were plated in triplicate on tryptic soy agar plates with 30 mg/L of oxytetracycline. Oxytetracycline resistant bacteria were selected from surface water in Cheongmi Stream and were subjected to 16S rDNA analysis for oxytetracycline resistant species determination. Identified resistant strains were tested for resistance to various antibiotics. Results: Results from this study indicate that the dominant resistant organisms in this aquatic environment are from family Acinetobacter and family Aeromonas. As to culturable heterotrophic bacteria, Oxytetracycline resistant bacteria were present 0.45-0.93% during winter and 0.08-0.38% during summer. Most oxytetracycline resistant bacteria exhibited resistance to more than ten of the antibiotics studied. The diversity of oxytetracycline resistant bacteria in winter was higher than in summer. Conclusion: Most of these resistant bacteria are Gram negative and are closely related to pathogenic species. These results suggest that increasing multi-antibiotic resistant bacteria in the surface water environment has a close relation to the reckless use of antibiotics in livestock.

• The Korean Journal of Mycology
• /
• v.49 no.4
• /
• pp.497-505
• /
• 2021

Endophytic fungal strains were isolated from leaves, stems, and roots of Angelica gigas. The fungal strains were identified based on their morphological characteristics and molecular analysis of the internal transcribed spacer (ITS). A total 35 species of endophytic fungi were identified. The diversity between the endophytic fungal communities differed depending on the tissues of A. gigas. The isolated endophytic fungi were screened for antifungal activity against a pathogenic fungus, Phoma sp. Y11, using a dual culture method. Fourteen species of endophytic fungi showed the standout inhibition effect against the Y11 strain. The results suggest that the endophytic fungi isolated from A. gigas could be used as a biological control agent against leaf spot disease of A. gigas.

• The Plant Pathology Journal
• /
• v.34 no.1
• /
• pp.23-34
• /
• 2018

The Ralstonia solanacearum species complex (RSSC) can be divided into four phylotypes, and includes phenotypically diverse bacterial strains that cause bacterial wilt on various host plants. This study used 93 RSSC isolates responsible for potato bacterial wilt in Korea, and investigated their phylogenetic relatedness based on the analysis of phylotype, biovar, and host range. Of the 93 isolates, twenty-two were identified as biovar 2, eight as biovar 3, and sixty-three as biovar 4. Applied to the phylotype scheme, biovar 3 and 4 isolates belonged to phylotype I, and biovar 2 isolates belonged to phylotype IV. This classification was consistent with phylogenetic trees based on 16S rRNA and egl gene sequences, in which biovar 3 and 4 isolates clustered to phylotype I, and biovar 2 isolates clustered to phylotype IV. Korean biovar 2 isolates were distinct from biovar 3 and 4 isolates pathologically as well as genetically - all biovar 2 isolates were nonpathogenic to peppers. Additionally, in host-determining assays, we found uncommon strains among biovar 2 of phylotype IV, which were the tomato-nonpathogenic strains. Since tomatoes are known to be highly susceptible to RSSC, to the best of our knowledge this is the first report of tomato-nonpathogenic potato strains. These results imply the potential prevalence of greater RSSC diversity in terms of host range than would be predicted based on phylogenetic analysis.

• Journal of Crop Science and Biotechnology
• /
• v.11 no.4
• /
• pp.257-262
• /
• 2008

Genetic diversity of cultivated wheat is narrowing down and is increasingly becoming non-complacent in tackling new pathogenic races and adverse environmental situations. Wild relatives of wheat are rich repositories of beneficial genes that are capable of defying adverse situations. However, these wild species are not readily crossable with cultivated ones. The present study attempted to cross three wild wheat species as females with three cultivated species of varying ploidy to understand the intricate behaviour of hybrids in relation to cytology, morphology, and molecular recombination. Post-fertilization barriers caused hybrid recovery in wild species in contrast to cultivated species. Triticum monococcum did not produce hybrids in any of the crosses. Various degrees of chromosome anomalies and hybrid sterility were seen with hybrids of T. timopheevi and T. sphaerococcum. Cytoplasmic factors were suspected to add more to the abnormality. G genome from T. timopheevi could enhance more pairing between Band D of cultivated species. Precocity of certain chromosomes in laggard formation was evident, pointing towards evolutionary self balance of the genomes which prevented homeologous pairing. They are eliminated in hybrids. Molecular diversity clearly corroborated with genetic proximity of the species, which distinguished themselves by maintaining the genome homeology.

• Korean Journal of Food Science and Technology
• /
• v.53 no.3
• /
• pp.334-343
• /
• 2021

Various vegetables, including cucumbers, have a high probability of foodborne illness because they are usually eaten raw. In this study, we analyzed the 16S rRNA gene sequences of the cucumber (Cucumis sativus L.) microbiota. The diversity indices of cucumber cultivated in May were higher than in cucumber cultivated in November. At the phylum level, Proteobacteria, Firmicutes, and Actinobacteria were predominant. The classes generally comprised Gammaproteobacteria, Bacilli, Alphaproteobacteria, and Actinobacteria. At the genus level, the proportions of Aureimonas, Escherichia, and Microbacterium in samples from May were relatively high, whereas Enterococcus, Pseudomonas, and Rhizobium accounted for a higher proportion in samples from November. Moreover, it is noteworthy that potential pathogenic genera such as Acinetobacter, Aerococcus, Aureimonas, Enterobacter, Enterococcus, Escherichia, Pantoea, Pseudomonas, and Staphylococcus were detected. Although further studies on the characteristics of potential pathogens are required, our results can be used to improve the food safety of vegetables.

• Journal of Environmental Health Sciences
• /
• v.42 no.1
• /
• pp.34-40
• /
• 2016

Objectives: This study aims to examine the concentration, diversity, and antibiotic characteristics of penicillin G resistant enterobacteria present in pharmaceutical effluent. Methods: Water sampling was performed from a pharmaceutical company in Gyeonggi-do Province, Korea in March 2015. Water samples were plated in triplicate on tryptic soy agar plates with 32 mg/L of penicillin G. Penicillin G resistant enterobacteria were selected from the effluent and were subjected to 16S rRNA analysis for penicillin G resistant species determination. Identified resistant strains were tested for resistance to various antibiotics. Results: Penicillin G resistant enterobacteria were present at 6.2% as to culturable heterotrophic bacteria. Identified penicillin G resistant enterobacteria exhibited resistance to more than 10 of the antibiotics studied. These resistant bacteria are gram negative and are closely related to pathogenic species. Conclusion: Multi-antibiotic resistant bacteria in the effluent suggest a need for disinfection and advanced oxidation processes for pharmaceutical effluents.

• Genomics & Informatics
• /
• v.12 no.4
• /
• pp.136-144
• /
• 2014

Besides single-nucleotide variants in the human genome, large-scale genomic variants, such as copy number variations (CNVs), are being increasingly discovered as a genetic source of human diversity and the pathogenic factors of diseases. Recent experimental findings have shed light on the links between different genome architectures and CNV mutagenesis. In this review, we summarize various genomic features and discuss their contributions to CNV formation. Genomic repeats, including both low-copy and high-copy repeats, play important roles in CNV instability, which was initially known as DNA recombination events. Furthermore, it has been found that human genomic repeats can also induce DNA replication errors and consequently result in CNV mutations. Some recent studies showed that DNA replication timing, which reflects the high-order information of genomic organization, is involved in human CNV mutations. Our review highlights that genome architecture, from DNA sequence to high-order genomic organization, is an important molecular factor in CNV mutagenesis and human genomic instability.

• Mycobiology
• /
• v.49 no.1
• /
• pp.89-94
• /
• 2021

Forty-three (n = 43) endophytic fungi with different morphologic characteristics were from a medicinal plant Sceletium tortuosum, were utilized to investigate their antifungal effectiveness against pathogenic fungi. All fungal isolates exhibited antifungal activity against one or more pathogens in the dual culture test whereas only 33 fungal culture filtrates (77%) showed decent antifungal effect. Fusaria and Aspergillus were the dominate genus that displayed significant antifungal activity. Isolates GG02, GG09, ND15, and ND17 showed the broadest spectrum of antifungal activity. Furthermore, culture filtrate of Fusarium sp. DR08 exhibited a broad range of antifungal activity against all the pathogens. The results suggest endophytic fungi isolated from medicinal plant might be a source of novel bioactive molecules. To the best our knowledge, this is the first report on endophytic fungi isolated from native kougoed exhibiting antifungal activity against plant fungal pathogens.

• Journal of Microbiology and Biotechnology
• /
• v.28 no.2
• /
• pp.227-235
• /
• 2018

Foodborne illness represents a major threat to public health and is frequently attributed to pathogenic microorganisms on fresh produce. Recurrent outbreaks often come from vegetables that are grown close to or within the ground. Therefore, the first step to understanding the public health risk of microorganisms on fresh vegetables is to identify and describe microbial communities. We investigated the phyllospheres on Chinese cabbage (Brassica rapa subsp. pekinensis, N = 54). 16S rRNA gene amplicon sequencing targeting the V5-V6 region of 16S rRNA genes was conducted by employing the Illumina MiSeq system. Sequence quality was assessed, and phylogenetic assessments were performed using the RDP classifier implemented in QIIME with a bootstrap cutoff of 80%. Principal coordinate analysis was performed using a weighted Fast UniFrac matrix. The average number of sequence reads generated per sample was 34,584. At the phylum level, bacterial communities were composed primarily of Proteobacteria and Bacteroidetes. The most abundant genera on Chinese cabbages were Chryseobacterium, Aurantimonadaceae_g, Sphingomonas, and Pseudomonas. Diverse potential pathogens, such as Pantoea, Erwinia, Klebsiella, Yersinia, Bacillus, Staphylococcus, Salmonella, and Clostridium were also detected from the samples. Although further epidemiological studies will be required to determine whether the detected potential pathogens are associated with foodborne illness, our results imply that a metagenomic approach can be used to detect pathogenic bacteria on fresh vegetables.