• Journal of Environmental Science International
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• v.10 no.3
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• pp.239-245
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• 2001

This research was performed to investigate the dynamics of microbial community by RBC (Rotating Biological Contactor) using Rhodococcus sp. EL-GT and activated sludge. Cell counts revealed by DAPI were compared with culturable bacterial counts from nutrient agar. Colony counts on nutrient agar gave values 20~25% and 1~15% of cell counts (DAPI). The cell counts for the dynamics of bacterial community were determined by combination of in situ hybridization with fluorescently-labelled oligonyucleotide probes and epifluorescence microscopy. Around 90~80% of total cells visualized DAPI were also detected by the bacteria probe EUB 338. For both reactors proteobacteria belonging to the gamma subclass were dominant in the first stage (1 and 2 stage) and proteobacteria belonging to the gamma subclass were dominant in the last stage (3 and 4 stage).

• Journal of Life Science
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• v.23 no.6
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• pp.770-778
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• 2013

To determine the seasonal variation of bacterial community in the seawater of Gwangyang Bay, three hundred thirty six bacterial strains were isolated on February, May, July and October 2011. Amplified Ribosomal DNA Restriction Analysis (ARDRA) was used to construct the phylotyes of the isolates using the restriction endonuclease, Hae III. Diversity indices of ARDRA patterns were calculated. One hundred and one phylotypes including 40 unique pylotypes were found at the 80% similarity level. Partial 16S rRNA genes of one hundred thirty nine strains representing each phylotypes were sequenced and compared. Bacterial community composed of 4 different phyla which include Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes. Proteobacteria was the prevailing phylum in all seasons, followed by Bacteroidetes in winter, spring and autumn while Actinobacteria in summer. At the family level, Flavobacteriaceae dominated in winter and spring and Pseudoalteromonadaceae did in summer and autumn. Genera Altererythrobacter, Loktanella, Pseudoalteromonas and Vibrio were encountered in all seasons. The most diverse bacterial community was found in autumn followed by the order of spring, winter and summer.

• Korean Journal of Environmental Agriculture
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• v.38 no.3
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• pp.185-196
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• 2019

BACKGROUND: This study investigated the effects of rice genetically modified to be resistant against rice blast and rice bacterial blight on the soil microbial community. A comparative analysis of the effects of rice genetically modified rice choline kinase (OsCK1) gene for disease resistance (GM rice) and the Nakdong parental cultivar (non-GM rice) on the soil microbial community at each stage was conducted using rhizosphere soil of the OsCK1 and Nakdong rice. METHODS AND RESULTS: The soil chemistry at each growth stage and the bacterial and fungal population densities were analyzed. Soil DNA was extracted from the samples, and the microbial community structures of the two soils were analyzed by pyrosequencing. No significant differences were observed in the soil chemistry and microbial population density between the two soils. The taxonomic analysis showed that Chloroflexi, Proteobacteria, Firmicutes, Actinobacteria, and Acidobacteria were present in all soils as the major phyla. Although the source tracking analysis per phylogenetic rank revealed that there were differences in the bacteria between the GM and non-GM soil as well as among the cultivation stages, the GM and non-GM soil were grouped according to the growth stages in the UPGMA dendrogram analysis. CONCLUSION: The difference in bacterial distributions between Nakdong and OsCK1 rice soils at each phylogenetic level detected in microbial community analysis by pyrosequencing may be due to the genetic modification done on GM rice or due to heterogeneity of the soil environment. In order to clarify this, it is necessary to analyze changes in root exudates along with the expression of transgene. A more detailed study involving additional multilateral soil analyses is required.

• Korean Journal of Environmental Agriculture
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• v.39 no.1
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• pp.1-9
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• 2020

BACKGROUND: The aim of this study was to investigate the soil chemical properties and soil bacterial community of the cropping system for Cnidium officinale Makino. METHODS AND RESULTS: The bacterial community was analyzed for the relative abundance and principal coordinated analysis (PCoA analysis) by using by Illumina Miseq sequencing. The correlation analysis between soil chemical properties and soil bacterial community were analyzed by Spearman's rank correlation and DISTLM analysis. Soil bacterial community (phylum and class) showed two distinct clusters consisting of cluster 1 (first cropping) and cluster 2 (continuous cropping) from 2 different cultivation methods of Cnidium officinale Makino. PCoA and DISTLM analyses showed that soil pH and Ca significantly affected soil bacterial community in cultivation area of Cnidium officinale Makino. In addition, Spearman's rank correlation showed significant correlation between relative abundance (Acidobacteria and Actinobacteria) and soil factors (soil pH and Ca). CONCLUSION: The results of this study were considered to be important for determining the correlation between soil properties and soil bacterial community of the cropping method for Cnidium officinale Makino. Furthermore, the results will be helpful to investigate the cause of continuous cropping injury of the Cnidium officinale Makino by examining the changes of soil properties and soil bacterial communities.

• The Journal of the Korea Contents Association
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• v.17 no.12
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• pp.64-76
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• 2017

Biolgical activated carbon (BAC) processes are known to effectively remove organic pollutants in raw water, and biomass and attached bacterial species play an important role in removing process. In the present study, changes of bacterial biomass in granular activated carbon (GAC) process according to the depth and operating period were investigated. In addition, changes of bacterial biomass were also confirmed after UV exposure prior to the GAC process. Results from this this study showed that the bacterial biomass was decreased dependently according to the depth of GAC process. In case of UV pre-treatment, the bacterial biomass was declined significantly over the period of operation. However, changes in bacterial community were not shown during operation period without UV pre-treatment process. In conclusion, findings from this study may provide the useful information about the management of BAC process.

• Korean Journal of Microbiology
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• v.46 no.4
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• pp.352-358
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• 2010

Bacterial community composition in activated sludge wastewater treatment bioreactors were analyzed using 16S rRNA gene-based pyrosequencing for the four different wastewater treatment processes. Sequences within the orders Rhodocyclales, Burkholderiales, Sphingobacteriales, Myxococcales, Xanthomonadales, Acidobacteria group 4, Anaerolineales, Methylococcales, Nitrospirales, and Planctomycetales constituted 54-68% of total sequences retrieved in the activated sludge samples, which demonstrated that a few taxa constituted majority of the activated sludge bacterial community. The relative ratio of the order members was different for each treatment process, which was assumed to be affected by different operational and environmental conditions of each treatment process. In addition, activated sludge had very diverse bacterial species (Chao1 richness estimate: 1,374-2,902 operational taxonomic units), and the diversity was mainly originated from rare species. Particularly, the bacterial diversity was higher in membrane bioreactor than conventional treatment processes, and the long solids retention time of the operational strategy of the membrane bioreactor appeared to be appropriate for sustaining diverse slow growing bacteria. This study investigating bacterial communities in different activated sludge processes using a high-throughput pyrosequencing technology would be helpful for understanding microbial ecology in activated sludge and for improving wastewater treatment in the future.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.287-295
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• 2005

In order to compare bacteria] community structure and diversity in activated sludges, terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16s rDNAs was analyzed for 31 domestic and industrial wastewater treatment plants (WTPs). Regardless of the characteristics of the wastewaters, the bacteria] community structures of activated sludges appeared diverse and complex. In particular, activated sludges in domestic WTPs contained higher bacterial diversity than those in industrial WTPs. It was also found that terminal restriction fragment (T-RF) profiles derived from domestic WTPs were very similar with each other, although activated sludges were collected from different plants at different locations. Interestingly, activated sludges of a WTP where restaurant and toilet sewages of a company were managed showed a bacterial community structure similar to that of domestic WTPs. Activated sludges in leather industria] WTPs also showed a high similarity. However, other wastewaters possessed different bacterial communities, so that overall similarity was as low as about $30\%$. Since activated sludges from WTPs for domestic wastewaters and a company sewage appeared to hold similar bacterial communities, it was necessary to confirm if similar wastewaters induce a similar bacterial community. To answer this question, analysis of T-RFs for activated sludges, taken from another 12 domestic WTPs, was conducted by using a 6­FAM$^{TM}$-Iabeled primer and an automated DNA sequencer for higher sensitivity. Among 12 samples, it was again found that T-RF profiles of activated sludges from Yongin, Sungnam, Suwon, and Tancheon domestic WTPs in Kyonggi-do were very similar with each other. On the other hand, T-RF profiles of activated sludges from Shihwa and Ansan WTPs were quite different from each other. It was thought that this deviation was caused by wastewaters, since Ansan and Shihwa WTPs receive both domestic and industrial wastewaters. From these results, it was tentatively concluded that similar bacterial communities might be developed in activated sludges, if WTPs treat similar wastewaters.

• Korean Journal of Microbiology
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• v.43 no.1
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• pp.14-18
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• 2007

The bacterial community structures at 2 sponge species belonging to the genus Baikalospongia and Lubomirskia in Lake Baikal were analyzed with fluorescent in situ hybridization (FISH) method. The total bacterial numbers in the genus Baikalospongia ranged from $7.2{\times}10^{7}\;to\;4.2{\times}10^{8}\;cells/ml$, and those in Lubomirskia from $1.2{\times}10^{8}\;to\;1.6{\times}10^{8}\;cells/ml$, while those of lake water were from $2.3{\times}7.7{\times}10^{5}\;cells/ml$. Total bacterial numbers in the sponges were $10^{3}-10^{4}$ times higher than those of lake water. In the genera Baikalospongia and Lubomirskia, the proportions of other unidentified bacterial groups to the Bacteria were 42.0-60.3% and 40.7-51.9%, respectively. These proportions were similar to those in lake water (22.6-46.3%). These results suggest that bacterial compositions in Lake Baikal water and sponges are highly unique.

• Journal of Microbiology and Biotechnology
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• v.20 no.8
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• pp.1230-1239
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• 2010

Five bacterial species, capable of degrading the recalcitrant organic compounds (ROCs) diethyleneglycol monomethylether (DGMME), 1-amino-2-propanol (APOL), 1-methyl-2-pyrrolidinone (NMP), diethyleneglycol monoethylether (DGMEE), tetraethyleneglycol (TEG), and tetrahydrothiophene 1,1-dioxide (sulfolane), were isolated from an enrichment culture. Cupriavidus sp. catabolized $93.5{\pm}1.7$ mg/l of TEG, $99.3{\pm}1.2$ mg/l of DGMME, $96.1{\pm}1.6$ mg/l of APOL, and $99.5{\pm}0.5$ mg/l of NMP in 3 days. Acineobacter sp. catabolized 100 mg/l of DGMME, $99.9{\pm}0.1$ mg/l of NMP, and 100 mg/l of DGMEE in 3 days. Pseudomonas sp.3 catabolized $95.7{\pm}1.2$ mg/l of APOL and $99.8{\pm}0.3$ mg/l of NMP. Paracoccus sp. catabolized $98.3{\pm}0.6$ mg/l of DGMME and $98.3{\pm}1.0$ mg/l of DGMEE in 3 days. A maximum $43{\pm}2.0$ mg/l of sulfolane was catabolized by Paracoccus sp. in 3 days. When a mixed culture composed of the five bacterial species was applied to real wastewater containing DGMME, APOL, NMP, DGMEE, or TEG, 92~99% of each individual ROC was catabolized within 3 days. However, at least 9 days were required for the complete mineralization of sulfolane. Bacterial community diversity, analyzed on the basis of the TGGE pattern of 16S rDNA extracted from viable cells, was found to be significantly reduced in a conventional bioreactor after 6 days of incubation. However, biodiversity was maintained after 12 days of incubation in an electrochemical bioreactor. In conclusion, the electrochemical reduction reaction enhanced the diversity of the bacterial community and actively catabolized sulfolane.

• Journal of Microbiology and Biotechnology
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• v.24 no.5
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• pp.648-660
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• 2014

Doenjang, a traditional Korean fermented soybean paste, is made by mixing and ripening meju with high salt brine (approximately 18%). Meju is a naturally fermented soybean block prepared by soaking, steaming, and molding soybean. To understand living bacterial community migration and the roles of bacteria in the manufacturing process of doenjang, the diversity of culturable bacteria in meju and doenjang was examined using media supplemented with NaCl, and some physiological activities of predominant isolates were determined. Bacilli were the major bacteria involved throughout the entire manufacturing process from meju to doenjang; some of these bacteria might be present as spores during the doenjang ripening process. Bacillus siamensis was the most populous species of the genus, and Bacillus licheniformis exhibited sufficient salt tolerance to maintain its growth during doenjang ripening. Enterococcus faecalis and Enterococcus faecium, the major lactic acid bacteria (LAB) identified in this study, did not continue to grow under high NaCl conditions in doenjang. Enterococci and certain species of coagulase-negative staphylococci (CNS) were the predominant acid-producing bacteria in meju fermentation, whereas Tetragenococcus halophilus and CNS were the major acid-producing bacteria in doenjang fermentation. We conclude that bacilli, LAB, and CNS may be the major bacterial groups involved in meju fermentation and that these bacterial communities undergo a shift toward salt-tolerant bacilli, CNS, and T. halophilus during the doenjang fermentation process.