Biomedical subjects

Wen-Tso Liu

Publications and source records attributed to Wen-Tso Liu.

23 records · Page 2Linked to original sources

PubMed2002

Diversity and distribution of a deeply branched novel proteobacterial group found in anaerobic-aerobic activated sludge processes.

A novel coccobacilli group found previously in enhanced biological phosphorus removal (EBPR) systems was further revealed to have a high degree of diversity and distribution in various activated sludge systems. Phylogenetic analysis based on 14 existing and 18 newly retrieved 16S rRNA sequences revealed that these sequences formed a novel cohesive cluster with seven subgroups in the gamma-Proteobacteria. Fluorescence in situ hybridization with a set of probes designed specifically targeting the novel group at different hierarchical levels showed that the novel group with a coccoid (2-4 micro m) to occasionally long-rod (up to 20 micro m) shape widely distributed and in some cases predominated in sludge samples taken from nine lab- and full-scale EBPR systems (10-50% of total cells) and four conventional activated sludge systems (1-10%). Variation of predominance was also observed among those subgroups in systems showing deteriorated or effective EBPR activity.

Aerobiosis↗

PubMed2002

Tetrasphaera elongata sp. nov., a polyphosphate-accumulating bacterium isolated from activated sludge.

A new meso-diaminopimelic acid-containing, gram-positive bacterium was isolated from an activated sludge reactor showing enhanced biological phosphorus removal activity. The isolate was an asporogenous oval to rod-shaped bacterium, but occasionally formed clumps. The Neisser staining was positive, suggesting intracellular polyphosphate granules. The isolate was an aerobic chemoheterotroph which was capable of utilizing various sugars, sugar alcohols and organic acids. It contained anteiso-C15:0, iso-C15:0, iso-C14:0 and C16:0 as the major cellular fatty acids, and menaquinone-8(H4) as the major quinone. The G+C content of the genomic DNA was 69.6 mol%. Analysis of the 16S rDNA sequence revealed that the isolate is a new member of the family Intrasporangiaceae. The closest relatives were Tetrasphaera species. On the basis of the phenotypic and phylogenetic distinctiveness of the isolate, it was concluded that the organism represents a new species in the genus Tetrasphaera, for which the name Tetrasphaera elongata sp. nov. is proposed. The type strain is strain Lp2T (= JCM 11141T = DSM 14184T).

Actinomycetales↗

PubMed2002

Kineosphaera limosa gen. nov., sp. nov., a novel Gram-positive polyhydroxyalkanoate-accumulating coccus isolated from activated sludge.

A high-G+C gram-positive, motile, non-spore-forming coccus capable of accumulating significant amounts of polyhydroxyalkanoate (PHA) was isolated from an inefficient biological phosphorus removal activated sludge reactor. The cell wall of strain Lpha5T was characterized by the presence of meso-diaminopimelic acid, menaquinone MK-8(H4) and a complex fatty-acid pattern consisting of C16:0 and at least five other major straight-chain saturated and unsaturated fatty acids. Strain Lpha5T also had a high G+C content (71.3 mol%). The nearest phylogenetic relative of strain Lpha5T, based on 16S rDNA sequence analysis, was the high-G+C gram-positive bacterium Dermatophilus congolensis (similarity value of 94%), of the family Dermatophilaceae, class Actinobacteria. As strain Lpha5T was distinct from D. congolensis in its morphological, phenotypical (i.e. its PHA-accumulating ability and fatty-acid profile) and genetic traits (phylogeny and G+C content), it is proposed that strain Lpha5T be designated as the type species of a novel genus within the Dermatophilaceae. The name Kineosphaera limosa is proposed for strain Lpha5T (= JCM 11399T = DSM 14548T).

Actinomycetales↗

PubMed2001

Characterization of microbial consortia in a terephthalate-degrading anaerobic granular sludge system.

The microbial composition and spatial distribution in a terephthalate-degrading anaerobic granular sludge system were characterized using molecular techniques. 16S rDNA clone library and sequence analysis revealed that 78.5% of 106 bacterial clones belonged to the delta subclass of the class Proteobacteria; the remaining clones were assigned to the green non-sulfur bacteria (7.5%), Synergistes (0.9%) and unidentified divisions (13.1%). Most of the bacterial clones in the delta-Proteobacteria formed a novel group containing no known bacterial isolates. For the domain Archaea, 81.7% and 18.3% of 72 archaeal clones were affiliated with Methanosaeta and Methanospirillum, respectively. Spatial localization of microbial populations inside granules was determined by transmission electron microscopy and fluorescent in situ hybridization with oligonucleotide probes targeting the novel delta-proteobacterial group, the acetoclastic Methanosaeta, and the hydrogenotrophic Methanospirillum and members of Methanobacteriaceae. The novel group included at least two different populations with identical rod-shape morphology, which made up more than 87% of the total bacterial cells, and were closely associated with methanogenic populations to form a nonlayered granular structure. This novel group was presumed to be the primary bacterial population involved in the terephthalate degradation in the methanogenic granular consortium.

Anaerobiosis↗

PubMed2000

Microbial community changes in biological phosphate-removal systems on altering sludge phosphorus content.

Biomarkers (respiratory quinones and cellular fatty acids) and denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes were used to characterize the microbial community structure of lab-scale enhanced biological phosphate-removal (EBPR) systems in response to altering sludge phosphorus (P) content. All the data suggest that the microbial community structures of sludge samples with a P content between 8 and 12.3% (sludge dry weight) (i.e. good EBPR activity) were very similar, but differed from those with 2% P content (i.e. no EBPR activity). For all samples analysed, ubiquinones Q-8 and Q-10, menaquinone MK-8(H4), and fatty acids C16:0, C16:1 omega9c and C18:1, omega11c were the major components. The dominance of Q-8, Q-10 and MK-8(H4) suggested that large numbers of organisms belonging to the beta and alpha subclasses of the Proteobacteria and the Actinobacteria from the high G+C Gram-positive bacteria, respectively, were present. DGGE analysis revealed at least 7-9 predominant DNA bands and numerous other fragments in each sample. Five major DGGE fragments from each of the 2% and 12% P-containing sludge samples, respectively, were successfully isolated and sequenced. Phylogenetic analysis of the sequences indicated that both 2% and 12% P-containing sludge samples shared three common phylotypes that were separately affiliated with a novel bacterial group from the gamma subclass of the Proteobacteria, two MK-8(H4)-containing actinobacteria previously isolated from the 2% P-containing sludge, and a Caulobacter spp. in the alpha subclass of the Proteobacteria. The phylogenetic analysis also revealed phylotypes unique to both sludge samples. Changes in sludge P content therefore had an effect on the composition and abundance of the predominant microbial populations, though specific phylotypes could not be unequivocally associated with EBPR.

Actinobacteria↗