• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1640-1645
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• 2006

We studied the diversity of the halophilic archaea and bacteria in crystallizer ponds of a Korean solar saltern by analyzing 16S rRNA gene libraries. Although diverse halophilic archaeal lineages were detected, the majority (56%) were affiliated with the uncultured and cultured Halorubrum group. Halophilic archaea that have been frequently observed in solar saltern environments previously, such as Halogeometricum, Halococcus, Haloarcula, and Haloferax, were not detected in our samples. The majority of clones (53%) belonged to the Cytophaga-Flavobacterium-Bacteroides and ${\alpha}-,\;{\gamma}-,\;and\;{\delta}-Proteobacteria$ groups, with 47% of the clones being affiliated with ${\gamma}-Proteobacteria$. We also identified new ${\delta}-Proteobacteria$-related bacteria that have not been observed in hypersaline environments previously. Our data show that the diversity of the halophilic archaea and bacteria in our Korean saltern differs from that of solar salterns found in other geographic locations. We also showed by quantitative real-time PCR analysis that bacteria can form a significant component of the microbial community in solar salterns.

• Korean Journal of Microbiology
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• v.37 no.2
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• pp.124-129
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• 2001

For elucidating the effect of salinity to the effect of wastewater treatment, the heterotrophic bacterial numbers, total bacterial numbers, and the bacterial community structure by FISH method were analyzed. The total bacterial numbers were not significantly changed by the salinity. But the heterotrophic bacterial numbers and bacterial community structures were drastically changed by the increase of salinity. In case of 1% salinity, the heterotrophic bacterial numbers and structure were slightly changed comparing to those of contol. In case of 2% and higher salinities, the numbers of heterotrophic bacteria and the proportions of Eubacteria, Proteobacteria $\alpha$-group, $\rho$-group and Cytophaga-Flavobacterium groups were deceasing. By these results, the salinity stress to bacterial community in waste water treatment was unveiled, and for sustaining the waste water treatment system, the salinity should be lower than 1%.

• Journal of Microbiology
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• v.37 no.4
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• pp.193-199
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• 1999

Fifty-eight strains showing different colony morphological characteristics on various media were isolated from marine coral (Plexauridae sp.) and ambient seawater near Mun-Sum, Cheju-Island in 1998. Bacterial diversity was studies by phylogenetic analysis of the partial 16S rRNA gene sequences. All isolates representing the bacterial domain included affiliates of the high G+C (59%) and los G+C (3%) subdivision of Gram positive bacteria, and the alpha (33%) and gamma (5%) subdivision of the Proteobacteria. The 16S rDNA sequence similarity of the isolates was in the 88.3 to 100% range (average, 95.6%) to reported sequence data. In the comparison of the isolates from marine coarl and ambient seawater, more diverse groups belonging to ${\alpha}$-Proteobacteria were preferentially obtained from seawater.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.66-73
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• 2011

Bacterial density distributions of gut microbes in the digestive organs of Harmonia axyridis collected from three different sources (JK, CK, and CJ) were $6.0{\times}10^4$ CFU/gut under aerobic culture condition and $8.0{\times}10^6$ CFU/gut under anaerobic culture condition. Seven colony types were observed under aerobic condition and three types of similarity were detected under anaerobic condition. In total, 116 strains, including 34 strains under aerobic condition, were isolated from the digestive organs of H. axyridis. Based on the analysis of the 16S rRNA gene sequence, aerobic gut microbes were assigned to the Proteobacteria, Actinobacteria, Firmicutes, and Deinococcus-Thermus. A large number of isolates belonged to the genus Bacillus and Staphylococcus of the Firmicutes commonly found in H. axyridis from different sites. Anaerobic gut microbes were found to be similar according to colony morphological, phylogenetic analysis using ARDRA. Eighty-two anaerobic gut microbes were clustered into 17 different ARDRA types according to HaeIII. Representative anaerobic gut microbes in each ARDRA group were divided into five species of ${\gamma}$-Proteobacteria based on 16S rRNA gene sequence analysis; Hafnia alvei, Enterobacter ludwigii, Enterobacter kobei, Pseudomonas oryzihabitans and Pseudomonas koreensis. Phylogenetic analysis indicated that about 70% of the isolates belonged to ${\gamma}$-Proteobacteria, suggesting predominance of gut microbes.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.177-183
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• 2007

Using complementation of RpoH deficient E. coli strain A7448, the rpoH gene encoding heat shock sigma factor 32 (${\sigma}^{32}$) from Methylovorus sp. strain SS1 DSM11726 was cloned and sequenced. Sequence analysis of a stretch of 1,796-bp revealed existence of an open reading frame encoding a polypeptide of 284 amino acid (32,006 dalton). Deduced amino acid sequence of the Methylovorus sp. strain SS1 RpoH showed that 59.6%, 39.1% and 51.4% identities with those of Nitrosomonas europaea (${\beta}$-proteobacteria), Agrobacterium tumefaciens ($\alpha$-proteobacteria) and E. coli (${\gamma}$-proteobacteria). The expression level of the functional ortholog of RpoH of Methylovorus sp. strain SS1 was increased transiently after heat induction, further indicating that it functions as a heat shock sigma factor.

• Journal of Microbiology and Biotechnology
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• v.18 no.11
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• pp.1826-1835
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• 2008

An autotrophic denitrification reactor (ADR-l) and a heterotrophic denitrification reactor (HDR-2) were operated to remove nitrate and nitrite in an anoxic environment in raw sewage. The $NO_3$-N removal rate of ADR-l was shown to range from 52.8% to 78.7%, which was higher than the $NO_3$-N removal rate of HDR-2. Specific denitrification rates (SDNR) of ADR-l and HDR-2 were 3.0 to 4.0 and 1.1 to $1.2\;mgNO_3$-N/gVSS/h, respectively. From results of restriction fragment length polymorphism (RFLP) of the 16S rRNA gene, Aquaspirillum metamorphum, Alcaligenes defragrans, and Azoarcus sp. were $\beta$-Proteobacteria that are affiliated with denitritying bacteria in the ADR-l. Specifically, Thiobacillus denitrificans was detected as an autotrophic denitrification bacteria. In HDR-2, the $\beta$-Proteobacteria such as Denitritying-Fe-oxidizing bacteria, Alcaligenes defragrans, Acidovorax sp., Azoarcus denitrificans, and Aquaspirillum metamorphum were the main bacteria related to denitrifying bacteria. The $\beta$-and $\alpha$-Proteobacteria were the important bacterial groups in ADR-l, whereas the $\beta$-Proteobacteria were the main bacterial group in HDR-2 based on results of fluorescent in situ hybridization (FISH). The number of Thiobacillus denitrificans increased in ADR-l during the operation period but not in HRD-2. Overall, the data presented here demonstrate that many heterotrophic denitritying bacteria coexisted with autotrophic denitrifying bacteria such as Thiobacillus denitrificans for nitrate removal in ADR-l. On the other hand, only heterotrophic denitritying bacteria were identified as dominant bacterial groups in HDR-2. Our research may provide a foundation for the complete nitrate removal in raw sewage of low-COD concentration under anoxic condition without any external organic carbon or the requirement of post-treatment.

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.169-174
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• 1998

To define the structure and diversity of bacterial communities in the aqutic ecosystem, Lake Soyang, the largest artificial reservoir in Korea, a new method, fluorescent in situ hybridization was applied. This technique relies on the specific hybridization of the nucleic acid probes to the naturally amplified intracellular rRNA. By this method, the bacterial community composition of Lake Soyang and bacterial numbers belong to eubacteria, proteobacteria and Cytophaga-Flavobacterium group were estimated. Total bacterial numbers ranged from $0.3{\times}10^6{\sim}2.0{\times}10^6cells{\cdot}ml^{-1}$, and vertical profile of total bacteria showed the peak at 2 and 5 m depths. The ratio of eubacteria to total bacteria were 22~100% and varied with depth and season. The percentage of Proteobacteria ${\alpha}$-group ranged 2.6~66.7%, ${\beta}$-group 4.5~53.5%, ${\gamma}$-group 4.6~76.7% and Cytophaga-Flavobacterium group 2.1~35.9%. Also, bacteria] community had spatial and temporal characteristics. The dominant groups were ${\beta}$-group in winter, ${\gamma}$-group in spring and early summer and ${\alpha}$-group in summer.

• Korean Journal of Microbiology
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• v.33 no.4
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• pp.257-261
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• 1997

To scrutinize the bacterial community composition of Lake Soyang in winter, bacterial numbers belonging to Eubacteria, Proteobacteria and Cytophaga-Flavobacterium group were estimated by using 16S and 23S rRNA targeted oligonucleotide probes. Total bacterial numbers ranged from $0.7{\times}10^6$ to $1.1{\times}10^6cells{\cdot}ml^{-1}$, and vertical profile of total bacteria showed a peak at 5 m depth. The ratio of eubacteria to total bacteria were 34~90% and at 5 m and 10 m depths those were low exhibiting, 39 and 34%, respectively. The percentage of proteobacteria ${\alpha}$-group ranged 10.8~28.7%, ${\beta}$-group 4.5~53.5%, ${\gamma}$-group 4.9~35.5% and Cytophaga-Flavobacterium group 6.1~21.1%. The dominant groups were ${\beta}$-group at 0, 2 and 5 m, ${\gamma}$-group at 10 m, ${\alpha}$-group at 30 m and Cytophaga-Flavobacterium group at 50 m depth. In winter season, Lake Soyang can be divided into three layer, 0~2 m, 5~10 m and 30~50 m, by the bacteria community composition. By this method, new informations about aquatic ecosystem were developed.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.86-95
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• 2015

To study the halobacterial diversity at the rhizospheric soil of coastal plant native to Dokdo islands, several host plant were selected and its rhizospheric soil was sampled. Soil sample was diluted serially and pure isolation was done by sub-culture using marine agar media. 26 halophilic strains cultivable at the marine medium containig concentration of 9.0% sodium chloride were selected among total 161 isolates. Their partial 16S rRNA gene sequences extracted from genomic DNA were analyzed and partially identified. Furthermore, to identify their genetic relationship, phylogenetic tree was deduced. Total 26 strains were belongs to Firmicutes (30.8%), Gamma proteobacteria (53.8%), Bacteroidetes (7.7%), Alpha proteobacteria (7.7%), and Actinobacteria (7.7%). These results showed the specific difference from previous researches which has been reported the microbial flora of soil or sea water around the Dokdo islands. Furthermore, 4 among 26 halophilic strains grew at above 12.0% NaCl concentrated marine broth, and 2 strains Idiomarina abyssalis LM4H23 and Halomonas huangheensis AS4H13 grew at 15.0% concentration. These halophilic strains thought to overcoming the severe stress like high salt concentration or variation derived from Dokdo-specific climate and might have unknown, specific relationship with their host coastal plant native to Dokdo islands.

• Microbiology and Biotechnology Letters
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• v.45 no.1
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• pp.71-80
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• 2017

Tea is the most popular beverage in the world. The three main types are green, black, and post-fermented. Post-fermented teas are produced by the microbial fermentation of sun-dried green tea leaves (Camellia sinensis). In this study, the composition of the bacterial communities involved in the production of traditional oriental post-fermented teas (Korean algacha, dancha, and Chinese pu-erh) were investigated using 16S rRNA gene analysis. The dominant microorganisms present in the post-fermented teas included the ${\alpha}$-proteobacteria Rhodobacteraceae and Sphingomonas, and the ${\gamma}$-proteobacteria Pantoea. Cluster analysis confirmed that the microbial populations present in both Korean and Chinese post-fermented teas grouped into the same class. Interestingly, the dominant microorganism present in the Korean post-fermented teas was a bacterium, while for the Chinese post-fermented tea, it was a fungus.