• Proceedings of the Microbiological Society of Korea Conference
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• 한국미생물학회 2003년도 International Meeting of the Microbiological Society of Korea
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• pp.26-33
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• 2003

We isolated and identifed culturable Arctic bacteria that have inhabited around Korean Arctic Research Station Dasan located at Ny-Alsund, Svalbard, Norway $(79^{\circ}N,\;12^{\circ}E)$. The pure colonies were inoculated into nutrient liquid media, genomic DNA was extracted, and phylogenetic analysis was performed on the basis of 16S rDNA sequences. Out of total 227 strains, 198 strains were overlapped or unidentified, and 43 bacteria were finally identified: 31 strains belonged to Pseudomonas, 7 strains Arthrobacter, two Flavobacterium sp., an Achromobacter sp., a Pedobacter sp., and a Psychrobacter sp. For isolation of diverse bacteria, we need more effective transport method than 3M petri-films, which were used for convenience of transportation that was restricted by volume. We also need to use other culture media than nutrient media. We expect these Arctic bacteria can be used for screening to develop new antibiotics or industrial enzymes that are active at low temperature.

• Proceedings of the Korean Society of Life Science Conference
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• 한국생명과학회 2007년도 제48회 학술심포지움 및 추계국제학술대회
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• pp.61.1-61.1
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• 2007

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• Korean Journal of Microbiology
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• 제45권2호
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• pp.155-162
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• 2009

A cultivation-based approach was employed to compare the culturable bacterial diversity associated with two phylogenetically closely related marine sponges, Spirastrella abata and Spirastrella panis, which have geologically overlapping distribution patterns. The bacteria associated with sponge were cultivated using MA medium supplemented with 3% sponge extracts. Community structures of the culturable bacteria of the two sponge species were analyzed with PCR-RFLP (restriction fragment length polymorphism) based on 16S rDNA sequences. The RFLP fingerprinting of 16S rDNA digested with HaeIII and MspI, revealed 24 independent RFLP types, in which 1-5 representative strains from each type were partially sequenced. The sequence analysis showed >98.4% similarity to known bacterial species in public databases. Overall, the microbial populations of two sponges investigated were found to be the members of the classes; Alphaproteobacteria, Gammaproteobacteria, Firmicutes, and Actinobacteria. The Alphaproteobacteria were predominant in the bacterial communities of the two sponges. Gammaproteobacteria represented 38.5% of bacterial community in S. abata. Whereas only 1.6% of this class was present in S. panis. Bacillus species were dominat in S. panis. Bacillus species were found to be 44.3% of bacterial species in S. panis, while they were only 9.7% in S. abata. It is interesting to note that Planococcus maritimus (8.1%, phylum Firmicutes) and Psychrobacter nivimaris (28.9%, phylum Gammaproteobacteria) were found only in S. abata. This result revealed that profiles of bacterial communities from the sponges with a close phylogenetic relationship were highly species-specific.

• Asian-Australasian Journal of Animal Sciences
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• 제31권11호
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• pp.1781-1794
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• 2018

Objective: This meta-analysis was conducted to evaluate the overall effect of direct-fed microbial (DFM) or probiotic supplementation on the log concentrations of culturable gut microbiota in broiler chickens. Methods: Relevant studies were collected from PubMed, SCOPUS, Poultry Science Journal, and Google Scholar. The studies included controlled trials using DFM supplementation in broiler chickens and reporting log concentrations of the culturable gut microbiota. The overall effect of DFM supplementation was determined using standardized mean difference (SMD) with a random-effects model. Subgroups were analyzed to identify pre-specified characteristics possibly associated with the heterogeneity of the results. Risk of bias and publication bias were assessed. Results: Eighteen taxa of the culturable gut microbiota were identified from 42 studies. The overall effect of DFM supplementation on the log concentrations of all 18 taxa did not differ significantly from the controls (SMD = -0.06, 95% confidence interval [-0.16, 0.04], p = 0.228, $I^2=85%$, n = 699 comparisons), but the 18 taxa could be further classified into three categories by the direction of the effect size: taxa whose log concentrations did not differ significantly from the controls (category 1), taxa whose log concentrations increased significantly with DFM supplementation (category 2), and taxa whose log concentrations decreased significantly with DFM supplementation (category 3). Category 1 comprised nine taxa, including total bacterial counts. Category 2 comprised four taxa: Bacillus, Bifidobacterium, Clostridium butyricum, and Lactobacillus. Category 3 comprised five taxa: Clostridium perfringens, coliforms, Escherichia coli, Enterococcus, and Salmonella. Some characteristics identified by the subgroup analysis were associated with result heterogeneity. Most studies, however, were present with unclear risk of bias. Publication bias was also identified. Conclusion: DFM supplementation increased the concentrations of some beneficial bacteria (e.g. Bifidobacterium and Lactobacillus) and decreased those of some detrimental bacteria (e.g. Clostridium perfringens and Salmonella) in the guts of broiler chickens.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• 제16권1호
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• pp.1-10
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• 2006

Concentration and identification of airborne bacteria in the regulated public facilities were examined with the six-stage cascade impactor. Geometric mean total and respirable concentrations of airborne bacteria were $404cfu/m^3$ and $194cfu/m^3$ in hospital, $931cfu/m^3$ and $358cfu/m^3$ in kindergarten, $294cfu/m^3$ and $134cfu/m^3$ in day-care center, and $586cfu/m^3$ and $254cfu/m^3$ in postpartum nurse center, respectively. As a result, culturable total and respirable concentrations of airborne bacteria were significantly highest in kindergarten and lowest in day-care center (p<0.05). The ratio of respirable to total concentration of airborne bacteria in the investigated public facilities was ranged from 30% to 40% but there was no significant difference among them (p>0.05). The mean I/O ratio of culturable total and respirable concentrations were 0.58 and 0.66 in hospital, 0.71 and 0.83 in kindergarten, 0.28 and 0.41 in day-care center, and 0.63 and 0.78 in postpartum nurse center, respectively. Day-care center showed the lowest I/O ratio of culturable total and respirable concentration of airborne bacteria (p<0.05) but a significant difference was not found among other facilities. Indoor concentration of airborne bacteria did not correlated significantly with indoor temperature and relative humidity (p>0.05) but had a significant positive correlation with $CO_2$ and surrounding condition (p<0.05). Staphylococcus spp., Micrococcus spp., Corynebacterium spp., and Bacillus spp. were dominant genera and amounted to over 95% of total airborne bacteria identified in the investigated public facilities. Size distributions of four dominant genera did not observed inconsistently regardless of type of public facility.

• Korean Journal of Microbiology
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• 제39권3호
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• pp.181-186
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• 2003

This study was performed to analyze quantitatively the number of living bacteria in forest soil samples collected from Mt. Keryong using improved direct viable count (DVC) and plate count (PC) methods. The number of living bacteria by DVC comprised 18～44% of the total direct count (TDC), whereas the number of living bacteria by PC was less than 1% of TDC. These results showed that viable but non-culturable (VBNC) bacteria existed in the soil with high percentages. Besides, DVC was proved to make it possible to make a quantitative detection of the VBNC bacteria. On the other hand, upon measuring the value from the conventional nutrient broth (NB) and $10^{-2}$ folded diluted nutrient broth (DNB), the values from the DNB showed 5 to 10 times higher than those from the conventional NB medium. These results indicate that oligotrophic bacterial groups, which could multiply in the low nutrient broth, abundantly exist in the soil ecosystem. It would also be possible to apply this kind of method to other substrate to make a quantitative detection of soil bacterial groups.

• Journal of Microbiology and Biotechnology
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• 제23권4호
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• pp.437-443
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• 2013

The diversity of culturable non-actinobacterial (NA) bacteria associated with four species of South China Sea gorgonians was investigated using culture-dependent methods followed by analysis of the bacterial 16S rDNA sequence. A total of 76 bacterial isolates were recovered and identified, which belonged to 21 species of 7 genera, and Bacillus was the most diverse genus. Fifty-one percent of the 76 isolates displayed antibacterial activities, and most of them belonged to the Bacillus genus. From the culture broth of gorgonian-associated Bacillus methylotrophicus SCSGAB0092 isolated from gorgonian Melitodes squamata, 11 antimicrobial lipopeptides including seven surfactins and four iturins were obtained. These results imply that Bacillus strains associated with gorgonians play roles in coral defense mechanisms through producing antimicrobial substances. This study, for the first time, compares the diversity of culturable NA bacterial communities among four species of South China Sea gorgonians and investigates the secondary metabolites of gorgonian-associated B. methylotrophicus SCSGAB0092.

• The Plant Pathology Journal
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• 제32권2호
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• pp.136-144
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• 2016

Pseudomonas fluorescens pc78 is an effective biocontrol agent for soil-borne fungal diseases. We previously constructed a P43-gfp tagged biocontrol bacteria P. fluorescens pc78-48 to investigate bacterial traits in natural ecosystem and the environmental risk of genetically modified biocontrol bacteria in tomato rhizosphere. Fluctuation of culturable bacteria profile, microbial community structure, and potential horizontal gene transfer was investigated over time after the bacteria treatment to the tomato rhizosphere. Tagged gene transfer to other organisms such as tomato plants and bacteria cultured on various media was examined by polymerase chain reaction, using gene specific primers. Transfer of chromosomally integrated P43-gfp from pc78 to other organisms was not apparent. Population and colony types of culturable bacteria were not significantly affected by the introduction of P. fluorescens pc78 or pc78-48 into tomato rhizosphere. Additionally, terminal restriction fragment length polymorphism profiles were investigated to estimate the influence on the microbial community structure in tomato rhizosphere between non-treated and pc78-48-treated samples. Interestingly, rhizosphere soil treated with strain pc78-48 exhibited a significantly different bacterial community structure compared to that of non-treated rhizosphere soil. Our results suggest that biocontrol bacteria treatment influences microbial community in tomato rhizosphere, while the chromosomally modified biocontrol bacteria may not pose any specific environmental risk in terms of gene transfer.

• Ocean and Polar Research
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• 제26권1호
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• pp.51-58
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• 2004

We isolated and identified culturable Arctic bacteria that had inhabited soils around the Korean Arctic Research Station Dasan located at Ny-Alsund, Svalbard, Norway $(79^{\circ}N,\;12^{\circ}E)$. The collected soils were diluted in distilled water; the diluted soil-water was spread on 3M petri-films at Dasan Station. The petri-films were transported to the laboratory at KORDI, and cultured at $4^{\circ}C$. Colonies grown on the petri-films were subsequently cultured on nutrient agar plates at $4^{\circ}C$ every 7 days. The pure colonies were inoculated into nutrient liquid media, genomic DNA was extracted, and phylogenetic analysis was performed on the basis of 165 rDNA sequences. A total of 227 strains of bacteria were isolated. Among them, 16S rDNA sequences of 185 strains were identical with those of known strains isolated in this study, and 42 strains were finally identified. Phylogenetic analysis using 16S rDNA indicated that the 30 strains belonged to Pseudomonas, 7 strains to Arthrobacter, two strains to Flavobacterium, and the remaining to Achromobacter, Pedobacter, and Psychrobacter. Among the 42 strains, 14 bacteria produced protease: they were 6 strains of Pseudomonax, 4 strains of Arthrobater, an Achromobacter strain, 2 strains of Flavobacterium, and a Pedohacter strain. We expect these Arctic bacteria can be used for screening to develop new industrial enzymes that are active at low temperatures.

• Korean Journal of Microbiology
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• 제42권2호
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• pp.116-124
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• 2006

In this study was performed to analyze quantitatively the number of viable but non-culturable bacteria in the Pine and Quercus forest soil by improved direct viable count (DVC) and plate count (PC) methods. The number of living bacteria of Pine and Quercus forest soil by PC method were less then 1% of DVC method. This result showed that viable but non-culturable (VBNC) bacteria existed in the forest soil with high percentage. Diversity and structure of VBNC bacterial populations in forest soil were analyzed by direct extracting of DNA and 16S rDNA-ARDRA from Pine and Quercus forest soil. Each of them obtained 111 clones and 108 clones from Pine and Quercus forest soil. Thirty different RFLP types were detected from Pine forest soil and twenty-six different RFLP types were detected from Quercus forest soil by HeaIII. From ARDRA groups, dominant clones were selected for determining their phylogenetic characteristics based on 16S rDNA sequence. Based on the 16S rDNA sequences, dominant clones from ARDRA groups of Pine forest soil were classified into 7 major phylogenetic groups ${\alpha}$-proteobacteria (12 clones), ${\gamma}$-proteobacteria (3 clones), ${\delta}$-proteobacteria (1 clone), Flexibacter/Cytophaga (1 clone), Actinobacteria (4 clones), Acidobacteria (4 clones), Planctomycetes (5 clones). Also, dominant clones from ARDRA groups of Quercus forest soil were classified into 6 major phylogenetic groups : ${\alpha}$-proteobacte,ia (4clones), ${\gamma}$-proteobacteria (2 clones), Actinobacteria (10 clones), Acidobacteria (8 clones), Planctomycetes (1 clone), and Verrucomicobia (1 clone). Result of phylogeneric analysis of microbial community from Pine and Quercus forest soils were mostly confirmed at uncultured or unidentified bacteria, VBNC bacteria of over 99% existent in forest soil were confirmed variable composition of unknown micro-organism.