• Journal of Species Research
• /
• 제12권2호
• /
• pp.158-164
• /
• 2023

In March 2021, marine sediment from East Sea samples were suspended in a 2% NaCl solution, and serial dilution was performed in fresh marine and Reasoner's 2A agar. Isolated bacterial strains were identified based on 16S rRNA gene sequences, and showed at least 98.7% sequence similarity with previously reported bacterial species. Finally, seven bacterial strains which were validly published but not reported in Korea, were obtained. These isolates were allocated to the orders Bacillales and Flavobacteriales. The three Flavobacteriales strains are classified into the family Flavobacteriaceae. The other four Bacillales belong to the families Bacillaceae and Paenibacillaceae. The seven unrecorded bacterial strains in this study are classified into seven different genera, which are assigned to Mesobacillus, Paenibacillus, Gramella, Gillisia, Arenibacter, Fictibacillus, and Brevibacillus. During the investigation, the possibility of excavation of various unrecorded species in domestic marine sediment was confirmed. Gram-staining, cell morphology, physiological and basic biochemical characteristics, and phylogenetic analysis were performed in this study and provided in the description of each strain.

• 환경생물
• /
• 제40권4호
• /
• pp.405-412
• /
• 2022

Suncheon Bay Ecological Park, possessing abundant fisheries and biological diversity, was registered as a Ramsar wetland in Korea. Approximately 300 bacterial strains were isolated from the Suncheon Bay in a comprehensive study of indigenous prokaryotic species conducted during 2019-2020 in South Korea. A total of 12 bacterial strains were identified using 16S rRNA gene sequencing, demonstrating >98.7% sequence similarity with validly published species. These species were determined to be unrecorded bacterial species in Korea. A total of six strains were isolated from brackish water and Phragmites communis Trin (reed) species. These unrecorded species were phylogenetically diverse and belonged to three classes, six orders, and ten genera. Regarding the genus and class levels, the previously unrecorded species belonged to Jiella, Martelella, Rhizobium, Paracoccus, Rhodovulum, and Altererythrobacter of the class Alphaproteobacteria; Mycolicibacterium, Demequina, and Microbacterium of the class Actinobacteria; Confluentibacter of the class Flavobacteria. The twelve species were further characterized by gram staining, colony and cell morphology, biochemical properties, and phylogenetic position.

• Journal of Species Research
• /
• 제12권spc2호
• /
• pp.54-59
• /
• 2023

To obtain unrecorded bacterial species from Korean islands, various samples were collected from the islands in 2022. After plating the samples on marine agar or Reasoner's 2A, and incubating aerobically, approximately 1,200 bacterial strains were isolated and identified using 16S rRNA gene sequences. A total of 10 strains showed ≥98.7% 16S rRNA gene sequence similarity with the bacterial species that were validly published but not reported in Korea. The unrecorded bacterial strains belong to three phyla, five classes, 10 orders, 10 families, and 10 genera, which are assigned to Sphingomonas, Falsirhodobacter and Asticcacaulis of the class Alphaproteobacteria; Colwellia and Halomonas of the class Gammaproteobacteria; Chitinophaga of the class Chitinophagia; Chryseobacterium of the class Flavobacteriia; Microlunatus, Zhihengliuella, and Streptomyces of the class Actinomycetia. The details of the unreported species including Gram reaction, colony and cell morphology, biochemical characteristics, and phylogenetic position are also provided in the description of the strains.

• Journal of Species Research
• /
• 제13권3호
• /
• pp.310-317
• /
• 2024

Various samples from island and coastal ecosystems in South Korea were investigated to discover unrecorded bacterial species. Soils from these areas, along with seawater samples, were plated on marine agar and R2A agar (containing 3% sea salt). From these samples, approximately 1,070 bacterial strains were isolated as single colonies and identified using 16S rRNA gene sequences. A total of 20 strains, which exhibited at least 98.7% similarity in their 16S rRNA gene sequences to those of validly published bacterial species not yet reported in Korea, were identified as unrecorded bacterial species. These strains belonged to three phyla, six classes, 10 orders, 14 families, and 16 genera. These were assigned as follows: Thioclava, Breoghania, Acidovorax, Erythrobacter, Paracoccus, Jiella, Aurantimonas, and Qipengyuania within the class Alphaproteobacteria; Pseudomonas, Cobetia, and Rheinheimera within the class Gammaproteobacteria; Aequorivita, Leeuwenhoekiella, and Polaribacter within the class Flavobacteriia; Algoriphagus within the class Cytophagia; and Microbacterium within the class Actinobacteria. The unreported species underwent further taxonomic characterization, which included assessments of Gram reaction, colony and cell morphology, biochemical and phylogenetic characteristics.

• Journal of Microbiology and Biotechnology
• /
• 제18권11호
• /
• pp.1762-1767
• /
• 2008

Image contrast of whole bacteria was compared in Staphylococcus aureus and Escherichia coli depending on pre-stain suspension liquids by energy-filtering transmission electron microscopy. The two bacterial strains were suspended in three most commonly used liquids for negative staining (triple distilled water [DW], phosphate-buffered saline [PBS], and nutrient broth [NB]) and directly observed without staining or stained with neutralized potassium phosphotungstate (PTA), respectively. Even though in low contrast, unstained bacteria were observed owing to their inherent electron density and cell shape in zero-loss (elastic scattering) images. After being suspended in PBS, unstained bacteria appeared to have higher contrast and more refined periphery than DW-suspended ones, and extracellular appendage structures such as fimbriae and flagella could be discerned. The unstained bacteria appeared to be invariably surrounded with electron-lucent precipitates, possibly from PBS. As far as delineation of the structures, the combination of DW or PBS suspension with subsequent staining provided the most satisfactory results, as evidenced by the high contrast of bacterial morphology and appendage structures. However, after being suspended in NB and stained with PTA, bacteria often had too high contrast or poor staining, with electron-dense aggregates around the bacteria. These results suggest that suspension with concentrated organic aliquots including broth media before PTA staining could deteriorate image contrast, and should be used only in dilute form for visualizing bacterial morphology and appendage structures. Moreover the contrast enhancement of unstained bacteria by salt granules would be advantageous in demonstrating bacterial sorption of environmental particles like heavy metals, maintaining minimal contrast for cell imaging.

• The Plant Pathology Journal
• /
• 제38권3호
• /
• pp.239-247
• /
• 2022

Bacterial wilt caused by the pathogen Ralstonia solanacearum is a devastating disease of potato crops. Harmonizing immunity to pathogens and crop yield is a balance between productive, economic, and environmental interests. In this work, the agronomic performance of two events of potato cultivar INIA Iporá expressing the Arabidopsis thaliana EFR gene (Iporá EFR 3 and Iporá EFR 12) previously selected for their high resistance to bacterial wilt was evaluated under pathogen-free conditions. During two cultivation cycles, the evaluated phenotypic characteristics were emergence, beginning of flowering, vigor, growth, leaf morphology, yield, number and size of tubers, analyzed under biosecurity standards. The phenotypic characteristics evaluated did not show differences, except in the morphology of the leaf with a more globose appearance and a shortening of the rachis in the transformation events with respect to untransformed Iporá. The Iporá EFR 3 genotype showed a ~40% yield decrease in reference to untransformed Iporá in the two trials, while Iporá EFR 12 did not differ statistically from untransformed Iporá. Iporá EFR 12 shows performance stability in the absence of the pathogen, compared to the untransformed control, positioning it as an interesting candidate for regions where the presence of the pathogen is endemic and bacterial wilt has a high economic impact.

• Journal of Microbiology and Biotechnology
• /
• 제5권6호
• /
• pp.309-314
• /
• 1995

Samples were collected from a commercial ethanol production plant to enumerate the bacterial contamination in each step of a starch based ethanol production process. Though the slurry of raw material used in the process carried bacteria with various colony morphology in the order of $10^4$ per ml, only the colonies of white and circular form survived and propagated through the processes to the order of $10^8$ per ml at the end of fermentation. Almost all of the bacterial isolates from the fermentation broth were lactic acid bacteria. Heterofermentative Lactobacillus fermentum and L. salivarius, and a facultatively heterofermentative L. casei were major bacteria of an ethanol fermentation. In a batch fermentation L. fermentum was more detrimental than L. casei to ethanol fermentation. In a cell-recycled fermentation, ethanol productivity of 5.72 g $I^{-1} h^{-1}$ was obtained when the culture was contaminated by L. fermentum, whilst that of the pure culture was 9.00 g $1^{-1} h^{-1}$. Similar effects were observed in a cell-recycled ethanol fermentation inoculated by fermentation broth collected from an industrial plant, which showed a bacterial contamination at the level of 10$^8$ cells per ml.

• 환경생물
• /
• 제37권4호
• /
• pp.592-599
• /
• 2019

Ostrea denselamellosa and Eriocheir japonica samples were collected from the Seomjin River in 2019 as part of the "Research of Host-Associated Bacteria" research program. Almost 200 bacterial strains were isolated from the O. denselamellosa and E. japonica samples and subsequently identified by 16S rRNA gene sequencing. Among the bacterial isolates, ten strains possessed greater than 98.7% sequence similarity with published bacterial species that had not previously been recorded in Korea. These species were phylogenetically diverse, belonging to three phyla, four classes, seven orders, and eight genera. At the genus and class level, the previously unrecorded species belonged to Pseudoalteromonas, Aliivibrio, Rheinheimera, Leucothrix, and Shewanella of the class Gamma-proteobacteria, Olleya of the class Flavobacteriia, Algoriphagus of the class Cytophagia, and Lactococcus of the class Bacilli. The previously unrecorded species were further characterized by examining their Gram staining, colony and cell morphology, biochemical properties, and phylogenetic positions.

• Journal of Species Research
• /
• 제5권2호
• /
• pp.235-240
• /
• 2016

To investigate the indigenous prokaryotic species diversity in Korea, various environmental samples from diverse ecosystems were examined taxonomically. The isolated bacterial strains were identified based on 16S rRNA gene sequences, and those exhibiting at least 98.7% sequence similarity with known bacterial species but never reported in Korea were selected as unrecorded species. As an outcome of this study, 10 unrecorded bacterial species belonging to the phylum Firmicutes were discovered from various sources such as soil, tidal flat, fresh water, sea water, kimchi and gut of Fulvia mutica. The unrecorded species were assigned to 7 different genera of 5 families, namely Bacillus and Ornithinibacillus of Bacillaceae, Exiguobacterium of Exiguobacteriaceae, Brevibacillus and Paenibacillus of Paenibacillaceae, Staphylococcus of Staphylococcaceae, and Lactococcus of Streptococcaceae. The selected isolates were subjected to further taxonomic characterization including the analysis of Gram reaction, cellular and colonial morphology, biochemical activities, and phylogenetic trees. The descriptive information on the 10 unrecorded species are provided.

• Journal of Species Research
• /
• 제10권3호
• /
• pp.191-200
• /
• 2021

To study the biodiversity of bacterial species, here we report indigenous prokaryotic species of Korea. A total of 23 bacterial strains affiliated to the class Alphaproteobacteria were isolated from various environmental sources including seaweeds, seawater, fresh water, wetland/marsh, tidal sediment, plant roots, sewage and soil. Considering higher than 98.8% 16S rRNA gene sequence similarities and formation of a well-defined phylogenetic clade with named species, it was confirmed that each strain belonged to the predefined bacterial species of the class Alphaproteobacteria. There is no official report of these 23 species in Korea; 20 species of 16 genera (Mameliella, Yangia, Paracoccus, Ruegeria, Loktanella, Phaeobacter, Dinoroseobacter, Tropicimonas, Lutimaribacter, Litoreibacter, Sulfitobacter, Roseivivax, Labrenzia, Hyphomonas, Maricaulis, Thalassospira) in the order Rhodobacterales and 3 species of a single genus (Brevundimonas) in the order Caulobacterales. Gram-staining, cell morphology, basic biochemical characteristics, isolation sources, optimum temperature, growth media, and strain IDs are detailed in the species description as well as Table 1.