Journal of Microbiology

Research Support, Non-U.S. Gov't

Isolation, Characterization, and Abundance of Filamentous Members of Caldilineae in Activated Sludge: Dae-No Yoon , Soo-Je Park , So-Jeong Kim , Che Ok Jeon , Jong-Chan Chae , Sung-Keun Rhee; J. Microbiol. 2010;48(3):275-283. Published online June 23, 2010; DOI: https://doi.org/10.1007/s12275-010-9366-8

Abstract: Chloroflexi are currently believed to serve as backbone forming agents in the activated sludge of wastewater treatment plants (WWTPs). In this study, we isolated and characterized filamentous bacteria in the class Caldilineae of the phylum Chloroflexi in municipal WWTPs. Diversity analysis using Chloroflexi-specific 16S rRNA gene clone libraries showed that 97% of the clones belonged to the subdivision Anaerolineae comprising the two classes Anaerolineae (95%) and Caldilineae (2%). Clones of Caldilineae were related to a thermophilic filament Caldilinea aerophila with 93% 16S rRNA gene sequence similarity. We obtained filamentous isolates classified into the class Caldilineae showing the best match to C. aerophila with 89% 16S rRNA gene sequence similarity. Isolates showed no ability to assimilate glucose or N-acetylglucosamine or to degrade biopolymers which were observed in filamentous Chloroflexi of WWTPs. The assessment of relative abundance based on quantitative PCR of the 16S rRNA gene indicated that members of the class Caldilineae comprised 12-19% of the Chloroflexi in the activated sludge. Additionally, fluorescence in situ hybridization experiments showed that diverse filamentous Caldilineae inhabit the activated sludge of municipal WWTPs. These findings yield insight into the role of filamentous mesophilic Caldilinea in stabilizing flocs of activated sludge in a wide range of WWTPs.

Journal Article

Monitoring of Algicidal Bacterium, Alteromonas sp. Strain A14 in its Application to Natural Cochlodinium polykrikoides Blooming Seawater Using Fluorescence In Situ Hybridization: Bo-Kyung Lee , Toshiya Katano , Shin-Ichi Kitamura , Myung-Joo Oh , Myung-Soo Han; J. Microbiol. 2008;46(3):274-282. Published online July 5, 2008; DOI: https://doi.org/10.1007/s12275-007-0238-9

Abstract: The red tide of dinoflagellate, Cochlodinium polykrikoides has frequently occurred in coastal waters, causing severe damage to fisheries. In the present study, the algicidal bacterium Alteromonas sp. A14 isolated from the southern coast of Korea was applied to a red tide of C. polykrikoides in a laboratory experiment. In the experiment, the abundance of the strain A14 was monitored using fluorescence in situ hybridization. Inoculation of the A14 at a final cell density of 9.0×105 cells/ml caused a significant decrease in C. polykrikoides abundance from 1,830 to 700 cells/ml during 2 days, while abundances of harmless diatoms rapidly increased from 3 days. Abundances of both A14 and other bacteria increased to 1 day. After 1 day, with flagellate abundance increased, bacterial abundance decreased. Finally, algicidal bacterial abundance decreased to 3.5×104 cells/ml. In the biological control of harmful algal blooms, in addition to decrease in target algal abundance and not occurrence of other harmful blooms, decrease in abundance of utilized organism is also important. This study emphasizes the importance of monitoring the inoculated bacterium when applying bacterium to natural seawater.

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