• Journal of Species Research
• /
• v.5 no.2
• /
• pp.241-253
• /
• 2016

In 2014, as a subset study to discover indigenous prokaryotic species in Korea, a total of 33 bacterial strains assigned to the class Gammaproteobacteria were isolated from diverse environmental samples collected from soil, tidal flat, freshwater, seawater, oil-contaminated soil, and guts of animal. From the high 16S rRNA gene sequence similarity (>98.5%) and formation of a robust phylogenetic clade with the closest species, it was determined that each strain belonged to each independent and predefined bacterial species. There is no official report that these 33 species have been described in Korea; therefore, 1 strain of the Aeromonadales, 6 strains of the Alteromonadales, 3 strains of the Chromatiales, 5 strains of the Enterobacteriales, 4 strains of the Oceanospirillales, 11 strains of the Pseudomonadales, and 3 strains of the Xanthomonadales within the Gammaproteobacteria are described for unreported bacterial species in Korea. Gram reaction, colony and cell morphology, basic biochemical characteristics, and isolation sources are also described in the species description section.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.9
• /
• pp.1335-1342
• /
• 2020

The identification of bacterial pathogens to humans is critical for environmental microbial risk assessment. However, current methods for identifying pathogens in environmental samples are limited in their ability to detect highly diverse bacterial communities and accurately differentiate pathogens from commensal bacteria. In the present study, we suggest an improved approach using a combination of identification results obtained from multiple databases, including the multilocus sequence typing (MLST) database, virulence factor database (VFDB), and pathosystems resource integration center (PATRIC) databases to resolve current challenges. By integrating the identification results from multiple databases, potential bacterial pathogens in metagenomes were identified and classified into eight different groups. Based on the distribution of genes in each group, we proposed an equation to calculate the metagenomic pathogen identification index (MPII) of each metagenome based on the weighted abundance of identified sequences in each database. We found that the accuracy of pathogen identification was improved by using combinations of multiple databases compared to that of individual databases. When the approach was applied to environmental metagenomes, metagenomes associated with activated sludge were estimated with higher MPII than other environments (i.e., drinking water, ocean water, ocean sediment, and freshwater sediment). The calculated MPII values were statistically distinguishable among different environments (p < 0.05). These results demonstrate that the suggested approach allows more for more accurate identification of the pathogens associated with metagenomes.

• Journal of Species Research
• /
• v.9 no.2
• /
• pp.85-104
• /
• 2020

In 2019, after a comprehensive investigation of indigenous prokaryotic species in Korea, a total of 12 bacterial strains assigned to the phylum Proteobacteria were isolated from soil. With the high 16S rRNA gene sequence similarity (>98.8%) and formation of a robust phylogenetic clade with the closest species, it was determined that each strain belonged to independent, predefined bacterial species. This study identified two species in the family Burkholderiaceae, one species in the family Comamonadaceae, two species in the family Oxalobacteraceae, one species in the family Micrococcaceae, one species in the family Bradyrhizobiaceae, one species in the family Methylobacteriaceae, one species in the family Rhizobiaceae, one species in the family Rhodocyclaceae, and one species in the family Sphingomonadaceae. There is no official report about these 12 species in Korea, so are described as unreported bacterial species in Korea in this study. Gram reaction, basic biochemical characteristics, colony, and cell morphology are also described in the species description section.

• Korean Journal of Ecology and Environment
• /
• v.47 no.spc
• /
• pp.39-47
• /
• 2014

Sponge in Lake Baikal is an unique organism. Microorganisms in sponges are assumed as precious resources for bioactive materials. For understanding the bacterial community in Baikalian sponges by cultivation, 92 strains of bacteria were isolated from lake water and 2 species of sponges, Baikalospongia sp. and Lubomirskia sp., Thirty five bacterial strains are isolated from ambient water near the sponge, 27 bacterial strains from Baikalospongia sp., 30 bacterial strains from Lubomirskia sp.. As a result, 78.3% and 57.6% of isolated bacterial strains has amylase and protease activity respectively, while strains with cellulose and lipase activities were 38.0% and 34.8%. By 16S rRNA sequence analysis of selected strains, 13 strains which were isolated from Baikalospongia sp. were belong to Pseudomonas spp.. Whereas, 14 strains which were isolated from Lubomirskia sp. were Pseudomonas spp., Buttiauxella agrestis, Pseudomonas fluorescens, Yersinia ruckeri, Bacillus spp., Paenibacillus spp., Bacillus thuringiensis, Bacillus simplex, Brevibacterium spp., Acinetobacter lwoffii. In culture media, Pseudomonas spp. dominance was supposed that according to allelophathy.

• Korean Journal of Environmental Biology
• /
• v.42 no.2
• /
• pp.143-157
• /
• 2024

As part of the research program "Freshwater Prokaryotic Organisms Research and Discovery," freshwater samples were collected from the Nakdonggang River. After plating the samples on several culture media and incubating aerobically, approximately 900 bacterial strains were isolated and identified using 16S rRNA gene sequences. Among the bacterial isolates showing higher than 98.7% 16S rRNA gene sequence similarity with those of already confirmed bacterial species previously unreported in Korea, 29 strains were selected. These strains were phylogenetically diverse and belonged to 3 phyla, 6 classes, 13 orders, and 21 genera. At the genus level, these previously unreported species were found to be affiliated with Novosphingobium, Sphingomonas, Polymorphobacter, Croceibacterium, Devosia, Endobacterium, Agaricicola, Bradyrhizobium, Paracoccus, and Pseudotabrizicola of the class Alphaproteobacteria; Undibacterium, Azonexus, and Dechloromonas of the class Betaproteobacteria; Acinetobacter and Budvicia of the class Gammaproteobacteria; Streptomyces, Nocardioides, Mycobacterium, and Cellulomonas of the phylum Actinomycetota; Flavobacterium and Pedobacter of the phylum Bacteroidota. These species were further characterized by examining their Gram reaction, colony and cell morphologies, biochemical properties, and phylogenetic positions. Detailed descriptions of these 29 previously unreported species are provided.

• Korean Journal of Environmental Biology
• /
• v.38 no.2
• /
• pp.289-298
• /
• 2020

As part of the research program "2018 Rapid screening and identification of freshwater microorganisms using MALDI-TOF/MS library" freshwater samples were collected from a branch of the Nakdong River. Almost 300 antibiotic-resistant bacterial strains were isolated from freshwater samples and subsequently identified by 16S rRNA gene sequencing. Seventeen strains among the isolates shared high 16S rRNA gene sequence similarity (>99.0%) with known species that were not previously recorded in Korea, and each of the isolates also formed a robust phylogenetic clade with the closest species. These species were phylogenetically diverse, belonging to four phyla, seven classes, 10 orders, and 13 genera. At the genus and class level, the previously unrecorded species belonged to Rhodovarius, Xanthobacter, and Shinella of the class Alphaproteobacteria; Ottowia, Simplicispira, and Zoogloea of Betaproteobacteria; Pseudomonas, Acinetobacter, and Shewanella of Gammaproteobacteria; Arcobacter of Epsilonproteobacteria; Sphingobacterium of Sphingobacteriia; Trichococcus of Bacilli; and Leucobacter of Actinobacteria. The previously unrecorded species were further characterized by examining their gram-staining, colony and cell morphology, biochemical properties, and phylogenetic position.

• Journal of Species Research
• /
• v.7 no.2
• /
• pp.151-160
• /
• 2018

Seven bacterial strains, 15J4M-1, 15J13-8, 16MFM10, 15J1-8, SR1-5-4, 15J13-6, and 15J8-11 assigned to the phylum Actinobacteria, Bacteroidetes, and Firmicutes were isolated from soil samples collected from Jeju, Korea. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strains 15J4M-1, 15J13-8, 16MFM10, 15J1-8, SR1-5-4, 15J13-6, and 15J8-11 were most closely related to Bacillus selenatarsenatis $SF-1^T$ (with 99.4% similarity), Brevibacterium luteolum $CF87^T$ (99.5%), Carnobacterium iners CCUG $62000^T$ (99.6%), Exiguobacterium profundum $10C^T$ (99.3%), Larkinella insperata LMG $22510^T$ (99.3%), Pseudokineococcus lusitanus CECT $7306^T$ (99.4%), and Spirosoma endophyticum $EX36^T$ (99.3%), respectively. This is the first report of these seven species in Korea.

• Genomics & Informatics
• /
• v.8 no.2
• /
• pp.63-69
• /
• 2010

Monofunctional biosynthetic peptidoglycan transglycosylase (MBPT) catalyzes the formation of the glycan chain in bacterial cell walls from peptidoglycan subunits: N-acetylglucosamine (NAG) and acetylmuramic acid (NAM). Bifunctional glycosyltransferases such as the penicillin binding protein (PBP) have peptidoglycan glycosyltransferase (PGT) on their C terminal end which links together the peptidoglycan subunits while transpeptidase (TP) on the N terminal end cross-links the peptide moieties on the NAM monosaccharide of the peptide subunits to create the bacterial cell wall. The singular function of MBPT resembles the C terminal end of PBP as it too contains and utilizes a similar PGT domain. In this article we analyzed the infectious and non infectious protein sequences of MBPT from 31 different strains of bacteria using a variety of bioinformatic tools. Motif analysis, dot-plot comparison, and phylogenetic analysis identified a number of significant differences between infectious and non-infectious protein sequences. In this paper we have made an attempt to explain, analyze and discuss these differences from an evolutionary perspective. The results of our sequence analysis may open the door for utilizing MBPT as a new target to fight a variety of infectious bacteria.

• Mycobiology
• /
• v.48 no.5
• /
• pp.392-398
• /
• 2020

This study was conducted to understand the dynamics of microbial communities of soil microorganisms, and their distribution and abundance in the indigenous microorganisms (IMOs) manipulated from humus collected from the forest near the crop field. The soil microorganisms originated from humus and artificially cultured microbial-based soil amendments were characterized by molecular and biochemical analyses. The bacterial population (2 × 10⁶~13 × 10⁶ CFU/g sample) was approximately 100-fold abundant than the fungal population (2 × 10⁴~8 × 10⁴ CFU/g sample). The 16S rDNA and ITS sequence analyses showed that the bacterial and fungal communities in humus and IMOs were mainly composed of Bacillus and Pseudomonas, and Trichoderma and Aspergillus species, respectively. Some of the bacterial isolates from the humus and IMOs showed strong inhibitory activity against soil-borne pathogenic fungi Fusarium oxysporum and Sclerotinia sclerotiorum. These bacteria also showed the siderophore production activity as well as phosphate solubilizing activity, which are requisite traits for biological control of plant pathogenic fungi. These results suggest that humus and IMOs could be a useful resource for sustainable agriculture.

• Korean Journal Plant Pathology
• /
• v.14 no.2
• /
• pp.177-183
• /
• 1998

A DNA fragment which is involved in tolassin production was cloned to obtain a molecular marker of Pseudomonas tolaasii, a casual agent of bacterial brown blotch disease of oyster mushroom (Pleurotus ostreatus). Tolaasin is a lipodepsipeptide toxin and known as a primary disease determinant of the P. tolaasii. It is responsible for formation of white line in agar when P. tolaasii were cultured against white line reacting organisms (WLROs). White line negative mutants (WL-) were generated by conjugation between rifampicin resistant strain of P. tolaasii and E. coli carrying suicidal plasmid pSUP2021 : : Tn5. The ability of tolaasin production of the WL- mutants was examined by hemolysis test, pathogenicity test, and high pressure liquid chromatography (HPLC) analysis of culture filtrate. All of the WL- mutants were lost the ability of tolaasin production (Tol-). Genomic library of the Tol- mutant was constructed in pLAFR3 and the cosmid clone containing Tn5 was selected. DNA fragment fro franking region of Tn5 was cloned from the plasmid and used as a probe in Southern blot. DNA-DNA hybridization with the probe to total DNA from group of bacteria ecologically similar to P. tolaasii including WLORs, fluorescent Pseudomonads isolated from oyster mushroom, P. agarici, P. gingeri, and some of other species of Psedomonas showed that some of the tested bacteria do not have any hybridized band and others have bands sowing RFLP. The cloned DNA fragment or its nucleotide sequence will be useful in detection and identification of the P. tolaasii.