Journal of Microbiology

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

Diversity of Bacterial Community in Freshwater of Woopo Wetland: Keun Sik Baik , Seong Chan Park , Eun Mi Kim , Kyung Sook Bae , Jae-Hyung Ahn , Jong-Ok Ka , Jongsik Chun , Chi Nam Seong; J. Microbiol. 2008;46(6):647-655. Published online December 24, 2008; DOI: https://doi.org/10.1007/s12275-008-0135-x

Abstract: Diversity of bacterial community in water layer of Woopo wetland was investigated. Cultivable bacterial strains were isolated by the standard dilution plating technique and culture-independent 16S rRNA gene clones were obtained directly from DNA extracts of a water sample. Amplified rDNA restriction analysis (ARDRA) was applied onto both of the isolates and 16S rRNA gene clones. Rarefaction curves, coverage rate and diversity indices of ARDRA patterns were calculated. Representative isolates and clones of all the single isolate/clone phylotype were partially sequenced and analyzed phylogenetically. Sixty-four and 125 phylotypes were obtained from 203 bacterial isolates and 235 culture-independent 16S rRNA gene clones, respectively. Bacterial isolates were composed of 4 phyla, of which Firmicutes (49.8%) and Actinobacteria (32.0%) were predominant. Isolates were affiliated with 58 species. Culture-independent 16S rRNA gene clones were composed of 8 phyla, of which Proteobacteria (62.2%), Actinobacteria (15.5%), and Bacteroidetes (13.7%) were predominant. Diversity of 16S rRNA gene clones originated from cultivation-independent DNA extracts was higher than that of isolated bacteria.

Antagonism of Bacterial Extracellular Metabolites to Freshwater-Fouling Invertebrate Zebra Mussels, Dreissena polymorpha: Ji-Dong Gu , Ralph Mitchell; J. Microbiol. 2001;39(2):133-138.

Abstract: We investigated the antagonism of indigenous bacteria isolated from stressed mussels and their extra-cellular metabolites on the adult zebra mussel, Dreissena polymorpha. Selective bacterial isolates including Aeromonas media, A. salmonicida, A. veronii, and Shewanella putrefaciens, showed strong lethality against adult mussels and 100% mortality was observed within 5 days of incubation. Bacterial metabolites, fractionated and concentrated from stationary-phase culture supernatants of these bacterial isolates, displayed varying degrees of antagonistic effects on zebra mussels. Among the three size fractions examined, <5, 5-10, and >10 kDa, the most lethal fraction seems to be >10 kDa for three of the four isolates tested. Further chemical analyses of these size fractions revealed that the predominant constituents were polysaccharides and proteins. No 2-keto-3-deoxyoctanoic acid (2-KDO), deoxyri-bonucleic acids (DNA) or uronic acid were detectable. Extraction of supernatants of two antagonistic isolates with polar solvent suggested that polar molecules are present in the active fraction. Our data suggest that extracellular metabolites produced by antagonistic bacteria are also involved in disease development in zebra mussels and elucidation of the mechanisms involved may offer a novel strategy for control of biofouling invertebrates.

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