• Research in Plant Disease
• /
• v.29 no.4
• /
• pp.440-444
• /
• 2023

In August 2021, water-soaking symptoms of bacterial spot disease were observed on castor bean in a field in Gangseo District, Busan. Bacteria isolated from the lesion when cultured on tryptic soy agar appeared to be nonmucoid and pale green. To confirm whether the isolates were the causative agent of the spot disease, they were inoculated onto healthy castor bean plants. The same symptoms were observed on the inoculated tissue, and the bacteria were reisolated from the lesion. Furthermore, the isolates were consistent with the biochemical and physiological features of Pseudomonas capsici. Sequencing analysis using 16S rRNA and housekeeping genes (gyrB, rpoD) showed that the isolates shared a high sequence similarity with P. capsici. These results confirmed that the strains belonged to P. capsici. To our knowledge, this is the first report of bacterial spot disease caused by P. capsici on castor bean in Korea.

• Journal of Applied Biological Chemistry
• /
• v.66
• /
• pp.394-403
• /
• 2023

In the pursuit of sustainable and environmentally-friendly agricultural practices, we conducted an extensive study on the rhizosphere bacteria inhabiting soils that have been devoid of chemical fertilizers for an extended period exceeding 40 years. Through this investigation, we isolated a total of 80 species of plant growth-promoting rhizosphere bacteria and assessed their potential to enhance plant growth. Among these isolates, Burkholderia cepacia CD2 displayed remarkable plant growth-promoting activity, making it an optimal candidate for further analysis. Burkholderia cepacia CD2 exhibited a range of beneficial characteristics conducive to plant growth, including phosphate solubilization, siderophore production, denitrification, nitrate utilization, and urease activity. These attributes are well-known to positively influence the growth and development of plants. To validate the taxonomic classification of the strain, 16S rRNA gene sequencing confirmed its placement within the Burkholderia genus, providing further insights into its phylogenetic relationship. To delve deeper into the potential mechanisms underlying its plant growth-promoting properties, we sought to confirm the presence of specific genes associated with plant growth promotion in CD2. To achieve this, whole genome sequencing (WGS) was performed by Plasmidsaurus Inc. (USA) utilizing Oxford Nanopore technology (Abingdon, UK). The WGS analysis of the genome of CD2 revealed the existence of a subsystem function, which is thought to be a pivotal factor contributing to improved plant growth. Based on these findings, it can be concluded that Burkholderia cepacia CD2 has the potential to serve as a microbial fertilizer, offering a sustainable alternative to chemical fertilizers.

• Research in Plant Disease
• /
• v.11 no.2
• /
• pp.140-145
• /
• 2005

A collection of 12 Erwinia carotovora strains from blackleg diseased potato in Jeju island was characterized genetic diversity by 5. cayotovora subsp. atposeptica (Eca)-specific PCR, PCR-RFLP of the two genes (16S rRNA and pel) and repetitive sequence PCR (ERIC-PCR). The results were compared with those of the other E. carotovora representative strains. None of the blackleg strains produced PCR amplicons with Eca-specific primers in contrast to the single 690 bp amplicon obtained with Eca strains. In addition, on the basis of pel gene RFLP with Sau3AI, the blackleg strains belonged to the pattern 2 whereas Eca strains belonged to the other one (pattern 3). By analysis of 16S rDNA RELP generated with HinfI, the most strains including the E. carotovera subsp. carotovora (Ecc) representative strains used in this study belonged to the pattern 1 whereas the blackleg strains belonged to the pattern 2 except for one strain. Moreover, ERIC-PCR analysis showed that the blackleg strains were closely related to each other and had an unique DNA band. Based on these molecular approaches, we have confirmed that the blackleg disease of potato is caused by a different E. carotovora from Eca and Ecc in Jeju island.

• Journal of fish pathology
• /
• v.36 no.2
• /
• pp.263-275
• /
• 2023

Chum salmon (Oncorhynchus keta) is a species which returns to Korea for spawning and was produced as seed production at the Fisheries Resources Agency located in Uljin-gun, Gyeongsangbuk-do to preserve the species. However, farmed chum salmon showed symptoms of bacterial infection. Therefore, in this study, bacteria were isolated to identify the causative agent from chum salmon in October 2021. The isolated bacteria were identified based on the sequences of 16S rDNA, rpoD (RNA polymerase sigma factor σ⁷⁰), and vapA (A-layer) genes. Also, salinity-growth curve, biochemical characterization, antibiotic susceptibility test, and pathogenicity analysis were performed in four strains. As a result, four isolated strains were identified as Aeromonas salmonicida subsp. salmonicida. Additionally, the bacterial strains showed a decrease in growth as the salt concentration increased in the medium. All of the isolated strains exhibited γ-hemolysis, and the same biochemical properties. In the antimicrobial susceptibility test, all strains showed an inhibition zone of 40 to 44 mm for oxolinic acid, flumequine, and florfenicol. Pathogenic factors were assessed by RT-PCR at the mRNA level, and found that the four strains expresses the outer membrane ring of T3SS (ascV), inner membrane ring of T3SS (ascC), vapA, enterotoxin (act), and lipase (lip) genes which are well known to significantly contribute to the pathogenicity of A. salmonicida. The results of this study can be used as basic data to prevent A. salmonicida subsp. salmonicida occurring in sea-chum salmon in the future.

• Asian-Australasian Journal of Animal Sciences
• /
• v.30 no.10
• /
• pp.1456-1463
• /
• 2017

Objective: To investigate the effect of host genetics on gut microbial diversity, we performed a structural survey of the fecal microbiota of four purebred boar pig lines: Duroc, Landrace, Hampshire, and Yorkshire. Methods: The V3-V4 regions of the 16S rRNA genes were amplified and sequenced. Results: A total of 783 operational taxonomic units were shared by all breeds, whereas others were breed-specific. Firmicutes and Bacteroidetes dominated the majority of the fecal microbiota; Clostridia, Bacilli, and Bacteroidia were the major classes. Nine predominant genera were observed in all breeds and eight of them can produce short-chain fatty acids. Some bacteria can secrete cellulase to aid fiber digestion by the host. Butyric, isobutyric, valeric, and isovaleric acid levels were highest in Landrace pigs, whereas acetic and propionic acid were highest in the Hampshire breed. Heatmap was used to revealed breed-specific bacteria. Principal coordinate analysis of fecal bacteria revealed that the Landrace and Yorkshire breeds had high similarity and were clearly separated from the Duroc and Hampshire breeds. Conclusion: Overall, this study is the first time to compare the fecal microbiomes of four breeds of boar pig by high-throughput sequencing and to use Spearman's rank correlation to analyze competition and cooperation among the core bacteria.

• Journal of Life Science
• /
• v.25 no.6
• /
• pp.680-685
• /
• 2015

Previously, cellulase and xylanase producing microorganism, Bacillus subtilis NC1, was isolated from soil. Based on the 16S rRNA gene sequence and API 50 CHL test the strain was identified as Bacillus subtilis, and named as B. subtilis NC1. We cloned and sequenced the genes for cellulase and xylanase. Plus, the deduced amino acid sequences from the genes of cellulase and xylanase were determined and were also identified as glycosyl hydrolases family (GH) 5 and 30, respectively. In this study to optimize the medium parameters for cellulase production by B. subtilis NC1 the RSM (response surface methodology) based on CCD (central composite design) model was performed. Three factors, tryptone, yeast extract, and NaCl, for N or C source were investigated. The cellulase activity was measured with a carboxylmethyl cellulose (CMC) plate and the 3,5-dinitrosalicylic acid (DNS) methods. The coefficient of determination (R²) for the model was 0.960, and the probability value (p=0.0001) of the regression model was highly significant. Based on the RSM, the optimum conditions for cellulase production by B. subtilis NC1 were predicted to be tryptone of 2.5%, yeast extract of 0.5%, and NaCl of 1.0%. Through the model verification, cellulase activity of Bacillus subtilis NC1 increased from 0.5 to 0.62 U/ml (24%) compared to the original medium.

• The Plant Pathology Journal
• /
• v.19 no.1
• /
• pp.13-18
• /
• 2003

From 1996 to 1999, potato-growing areas in Korea were surveyed for identification and distribution of potato scab pathogens. Potato scab was widely distributed in the mass cultivation areas, especially in Jriu island, southern areas of Chonnam and Gyounggi provinces, and the alpine area of Gangwon province. Jeju island was the most affected area by this disease. A total of 55 Streptomyces strains were isolated from potato scab lesions, among which 40 strains were pathogenic on progeny tubers. Among the pathogenic strain, 21 strains were identified as previously described S. scabies, 7 Strains as S. turgidiscabies, and 5 Strains as S. acidiscabies, while 7 strains were observed as having distinct phenotypic properties. These strains were classified into six distinct clusters based on phenotypic characteristics and selected representative strains for each cluster. S. scabies (S33) had grey spores in a spiral chain. Mean-while, S. turgidiscabies (S27) had grey spores, S. acidiscabies (S71) had white spores, S. luridiscabiei (S63) had yellow-white spores, S. puniciscabiei (S77) had purple-red spores, and S. niveiscabiei (S78) had thin and compact white spores, all in a rectiflexuous chain. Pathogenicity was determined by the production of thaxtomin A and homologs of necl and ORFtnp genes. In TLC, representative strains S27, S71, S63, S77, and S78 produced a yellow band that co-migrated with the authentic thaxtomin A. However, thaxtomin A was not detected in chloroform extracts from oatmeal broth culture and Slice tuber tissue of S. luridiscabiei (S63) and S. puniciscabiei (S77) by HPLC analysis. In addition, no homologs of necl and ORFtnp genes in S. acidiscabies (S71), S. luridiscabiei (S63), S. puniciscabiei (S77), and S. niveiscabiei (S78) were detected by PCR and Southern hybridization analysis.

• Mycobiology
• /
• v.46 no.3
• /
• pp.224-235
• /
• 2018

Temperature is an important environmental factor that can greatly influence the cultivation of Auricularia cornea. In this study, lignin peroxidase, laccase, manganese peroxidase, and cellulose in A. cornea fruiting bodies were tested under five different temperatures ($20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$, $35^{\circ}C$, and $40^{\circ}C$) in three different culture periods (10 days, 20 days and 30 days). In addition, the V4 region of bacterial 16S rRNA genes in the substrate of A. cornea cultivated for 30 days at different temperatures were sequenced using next-generation sequencing technology to explore the structure and diversity of bacterial communities in the substrate. Temperature and culture days had a significant effect on the activities of the four enzymes, and changes in activity were not synchronized with changes in temperature and culture days. Overall, we obtained 487,694 sequences from 15 samples and assigned them to 16 bacterial phyla. Bacterial community composition and structure in the substrate changed when the temperature was above $35^{\circ}C$. The relative abundances of some bacteria were significantly affected by temperature. A total of 35 genera at five temperatures in the substrate were correlated, and 41 functional pathways were predicted in the study. Bacterial genes associated with the membrane transport pathway had the highest average abundance (16.16%), and this increased at $35^{\circ}C$ and $40^{\circ}C$. Generally, different temperatures had impacts on the physiological activity of A. cornea and the bacterial community in the substrate; therefore, the data presented herein should facilitate cultivation of A. cornea.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.1
• /
• pp.9-18
• /
• 2017

Nine bacilli with fibrinolytic activities were isolated from doenjang, a traditional Korean fermented soy food. Among them, RSB34 showed the strongest activity and was identified as Bacillus amyloliquefaciens by 16S rRNA and recA gene sequencing. During growth on LB up to 96 h, RSB34 showed the highest fibrinolytic activity ($83.23mU/{\mu}l$) at 48 h. Three bands of 23, 27, and 42 kDa in size were observed when the culture supernatant was analyzed by SDS-PAGE and 27 and 42 kDa bands by fibrin zymography. The gene encoding the 27 kDa fibrinolytic enzyme AprE34 was cloned by PCR. BLAST analyses confirmed that the gene was a homolog to genes encoding AprE-type proteases. aprE34 was overexpressed in Escherichia coli BL21(DE3) using pET26b(+). Recombinant AprE34 was purified and examined for its properties. The $K_m$ and $V_{max}$ values of recombinant AprE34 were $0.131{\pm}0.026mM$ and $16.551{\pm}0.316{\mu}M/l/min$, respectively, when measured using an artificial substrate, N-succinyl-ala-ala-pro-phe-p-nitroanilide. aprE34 was overexpressed in B. subtilis WB600 using pHY300PLK. B. subtilis transformants harboring pHYRSB34 (pHY300PLK with aprE34) showed higher fibrinolytic activity than B. amyloliquefaciens RSB34.

• Asian-Australasian Journal of Animal Sciences
• /
• v.30 no.4
• /
• pp.531-537
• /
• 2017

Objective: This experiment was conducted to explore the impact of diet on the ruminal microbial community in goats. Methods: Twelve goats were divided into two groups and fed complete feed (CF) or all forage (AF) diet. The total microbial DNAs in the rumen liquid were extracted. The V4 region of microbial 16S rRNA genes was amplified and sequenced using high-throughput. Information of sequences was mainly analyzed by QIIME 1.8.0. Results: The results showed that Bacteroidetes and Firmicutes were the most predominant microbial phyla in the rumen of all goats. At genus level, the abundance of fiber-digesting bacteria such as Ruminococcus and Lachnospiracea incertae sedis was significantly higher in AF than that in CF, while the levels of fat-degrading bacterium Anaerovibrio and protein-degrading bacterium Pseudomonas were opposite. The core shared genera, Prevotella and Butyrivibrio were widespread in the rumen of goats and no significant difference was observed in relative abundance between groups. Conclusion: We concluded that the richness of fiber-, protein-, and fat-digesting bacteria was affected by diet and tended to increase with the rise of their corresponding substrate contents in the ration; some bacteria shared by all goats maintained stable despite the difference in the ration, and they might be essential in maintaining the normal function of rumen.