• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.356-361
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• 2007

Recently, the development of various culture-independent identification techniques for environmental microbes has greatly enhanced our knowledge of microbial diversity. In particular, denaturing gradient gel electrophoresis (DGGE) of 16S rDNA fragments, generated using the polymerase chain reaction (PCR) is frequently used to examine the diversity of environmental bacterial populations. This method consists of direct extraction of the environmental DNA, amplification of the 200-600 bp 16S rDNA fragments with universal primers, and separation of the fragments according to their melting point on a denaturing gradient gel. In this study, we investigated the seaside microbial community in coastal areas of Busan, Korea, using culture-independent techniques. First, marine genomic DNA was extracted from seawater samples collected at Songjeong, Gwangahn, and Songdo Beaches. Then, PCR was used to amplify the bacterial 16S rDNA using universal primers, and DGGE was used to separate the amplified 500 bp 16S rDNA fragments. Finally, the tested 16S rDNA genes were further analyzed by sequencing. Based on these experiments, we found that DGGE analysis clearly showed variation among the regional groups. It can be used to monitor rapid changes in the bacterial diversity of various environments. In addition, the sequence analysis indicated the existence of many unculturable bacteria, in addition to Arcobacter, Pseudoaltermonas, and Vibrio species.

• Journal of Species Research
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• v.8 no.3
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• pp.249-258
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• 2019

Owing to a distinct environmental regime and anthropogenic effects, freshwater bacterial communities of urban streams are considered to be different from those of large freshwater lakes and rivers. To obtain unrecorded, freshwater bacterial species in Korea, water and sediment samples were collected from various urban streams of the Han River watershed in 2018. After plating the freshwater samples on R2A agar, approximately 1000 bacterial strains were isolated from the samples as single colonies and identified using 16S rRNA gene sequence analyses. A total of 26 strains, with >98.7% 16S rRNA gene sequence similarity with validly published bacterial species but not reported in Korea, were determined to be unrecorded bacterial species in Korea. The unrecorded bacterial strains were phylogenetically diverse and belonged to four phyla, six classes, 12 orders, 16 families, and 21 genera. At the generic level, the unreported species were assigned to Nocardioides, Streptomyces, Microbacterium, Kitasatospora, Herbiconiux, Corynebacterium, and Microbacterium of the class Actinobacteria; Paenibacillus and Bacillus of the class Bacilli; Caulobacter, Methylobacterium, Novosphingobium, and Porphyrobacter of the class Alphaproteobacteria; Aquabacterium, Comamonas, Hydrogenophaga, Laribacter, Rivicola, Polynucleobacter, and Vogesella of the class Betaproteobacteria; Arcobacter of the class Epsilonproteobacteria; and Flavobacterium of the class Flavobacteriia. The details of the 26 unreported species, including Gram reaction, colony and cell morphology, biochemical properties, and phylogenetic position are also provided in the strain descriptions.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.389-397
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• 2015

Dongchun, one of the representative streams in urban area, is a downstream that is connected to Hogyechun, Bujeonchun, Jeonpochun, Danggamchun, and Gayachun as its upstream. Hogyechun has been mostly covered with concrete structures for decades, causing sewage pollution from the upstream, overflow of the downstream region and other serious pollution that gave rise to many civil complaints from the residents nearby. In this study, we analyzed 3 stations, including control station for water quality and malodor changes of Hogyechun after applying the microbial augmentation (BM-2) for a few months including the rainy season. Amounts (g/h) of DO in the middle site (Middle) and the downstream site (Borim) increased by 1.7 times compared with the upstream site (Chuhae) after augmentation for about 2 months. Amounts (g/h) of COD and $NO_3{^-}N$ decreased by 2 and 1.7 times, respectively, in the middle and downstream sites while SS increased by 7.5 and 22 times in the middle and downstream sites, respectively. Moreover, odor removal efficiencies at the middle and downstream sites were 65% and 19%, respectively, indicating the microbial activity in reduction of malodor in the polluted stream. The dominant microbial species of the sampling sites were Hydrogenophaga caeni, Sphaerotilus natans, Acidovorax radicis, Acidovorax delafieldii, and Cloacibacterium rupense. Densities of the two species Sphaerotilus natans and Acidovorax delafieldii were significantly increased in the middle site after augmentation which possessed potential odor removal and denitrification activity, respectively. Potential pathogens (e.g., Arcobacter cryaerophilus) were also removed from the middle site after the implementation.