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Satoshi Tsuneda

Publications and source records attributed to Satoshi Tsuneda.

28 records · Page 2Linked to original sources
PubMed2004

Design of 16S rRNA-targeted oligonucleotide probes and microbial community analysis in the denitrification process of a saline industrial wastewater treatment system.

Three 16S rRNA-targeted oligonucleotide probes, namely, PSMg437 targeting several members of the genus Pseudomonas, Hlm474 targeting several members of the genus Halomonas, and Clw844 targeting several members of the genus Colwellia, were designed. The microbial community structure and nitrogen removal ability of nitrate-containing saline wastewater treatment systems with anaerobic packed bed and fluidized bed were monitored. Direct cell counting using fluorescence in situ hybridization (FISH) images revealed that various phylogenetic groups were evenly distributed in the anaerobic packed bed whereas members of the genus Halomonas were dominant particularly in the anaerobic fluidized bed. These results suggest that the microbial communities produced by different flow conditions correlated with denitrification ability in saline industrial wastewater treatment systems.

Bioreactors↗
PubMed2004

Monitoring the microbial population dynamics at the start-up stage of wastewater treatment reactor by terminal restriction fragment length polymorphism analysis based on 16S rDNA and rRNA gene sequences.

The microbial population dynamics at the start-up stage of a wastewater treatment reactor was investigated using terminal restriction fragment length polymorphism (T-RFLP) analysis based on 16S rDNA and rRNA gene sequences. The results of fragment peaks suggested that the number and activity of nitrifying bacteria increased in association with the start of nitrification, and the relative ratios of 16S rRNA of these bacteria changed prior to those of the 16S rDNA. Furthermore, multidimensional scaling (MDS) analysis revealed that the 16S rRNA exhibited wider dispersion than the 16S rDNA at the start-up stage, indicating that the diversity of 16S rRNA in the microbial communities was strongly affected by environmental changes.

Journal Article↗
PubMed2003

In situ PCR for visualizing distribution of a functional gene "amoA" in a biofilm regardless of activity.

In this study, ammonia-oxidizing bacteria present in biofilms resulting from a nitrifying reactor were detected by both a conventional FISH technique and an original in situ PCR technique. Both techniques showed that ammonia-oxidizing bacteria were found near the surface of the biofilms. However, after the biofilm had been exposed to 2 weeks of ammonia starvation, ammonia-oxidizing bacteria present in the biofilm could not be detected by fluorescence in situ hybridization (FISH) because they did not have sufficient copies of rRNA. In contrast, ammonia-oxidizing bacteria could be detected by in situ PCR with strong signal. It was thus demonstrated that a cell possessing a specific functional gene is detectable by in situ PCR regardless of its activity.

Ammonia↗
PubMed2003

Influence of growth phase on bacterial cell electrokinetic characteristics examined by soft particle electrophoresis theory.

The influence of incubation time on the electrokinetic properties of Escherichia coli, Pseudomonas putida, Alcaligenes faecalis, and Alcaligenes sp., was examined by electrophoretic mobility measurements and the results were discussed based on Ohshima's soft particle theory. The electrophoretic mobility of E. coli plotted against incubation time revealed that the mobility gradually increased from the outset of incubation to 7 h, which corresponded to the exponential growth and early stationary phase, and then decreased. For all strains, electrophoretic mobility leveled off to nonzero values in accordance with the increase in ionic concentration, which was a characteristic feature of soft particles. Soft particle analysis was carried out at the outset of incubation and the time when mobility reached a maximum in order to obtain the spatial charge density (ZN) and cell surface softness (1/lambda). ZN at the maximum electrophoretic mobility was more negative than that at the outset of incubation for E. coli, P. putida, and A. faecalis, while the ZN of Alcaligenes sp. almost remained unchanged. 1/lambda decreased for E. coli, but increased for Alcaligenes sp. and A. faecalis. These findings indicated that the cell growth phase affects both ZN and 1/lambda, although the dependencies of these parameters are unique to each bacterial strain.

Journal Article↗
PubMed2003

Extracellular polymeric substances responsible for bacterial adhesion onto solid surface.

The influence of extracellular polymeric substances (EPS) on bacterial cell adhesion onto solid surfaces was investigated using 27 heterotrophic bacterial strains isolated from a wastewater treatment reactor. Cell adhesion onto glass beads was carried out by the packed-bed method and the results were discussed in terms of the amount of each EPS component produced and cell surface characteristics such as zeta potential and hydrophobicity. Protein and polysaccharides accounted for 75-89% of the EPS composition, indicating that they are the major EPS components. Among the polysaccharides, the amounts of hexose, hexosamine and ketose were relatively high in EPS-rich strains. For EPS-poor strains, the efficiency of cell adhesion onto glass beads increased as the absolute values of zeta potential decreased, suggesting that electrostatic interaction suppresses cell adhesion efficiency. On the other hand, the amounts of hexose and pentose exhibited good correlations with cell adhesiveness for EPS-rich strains, indicating that polymeric interaction due to the EPS covering on the cell surface promoted cell adhesion. It was concluded that, if the EPS amount is relatively small, cell adhesion onto solid surfaces is inhibited by electrostatic interaction, and if it is relatively large, cell adhesion is enhanced by polymeric interaction.

Bacteria↗
PubMed2003

Simultaneous nitrification and denitrification by controlling vertical and horizontal microenvironment in a membrane-aerated biofilm reactor.

Nitrogen and carbon components in domestic modified wastewater were completely removed by simultaneous nitrification and denitrification using a membrane-aerated biofilm reactor where biofilm was fixed on a hollow-fiber membrane. To measure the spatial distribution of pH, ammonium and nitrate ions and to observe microbes inside the biofilm fixed on the membrane, microelectrodes and the fluorescence in situ hybridization (FISH) method were applied. Due to plug flow in the vertical direction (from the bottom to the top of the reactor), ammonium nitrogen was gradually removed and negligible nitrate nitrogen was detected throughout the reactor. FISH revealed that ammonia-oxidizing bacteria were mainly distributed inside the biofilm and other bacteria, which included denitrifying bacteria, were mainly distributed outside the biofilm and over the suspended sludge. In order to characterize bacterial activity in the vertical direction of the reactor, nitrification rates at lower, central and upper points were calculated using microelectrode data. The nitrification rate at the lower point was 7 and 125 times higher than those at the central and upper points, respectively. These results show that the removal of carbon and nitrogen compounds was accomplished efficiently by using various kinds of bacteria distributed vertically and horizontally in a single reactor.

Bacteria, Aerobic↗
PubMed2003

Characterization of nitrifying granules produced in an aerobic upflow fluidized bed reactor.

Since nitrification is the rate-determining step in the biological nitrogen removal from wastewater, many research studies have been conducted on the immobilization of nitrifying bacteria. In this research, granulation of nitrifying bacteria in an aerobic upflow fluidized bed (AUFB) reactor in a nitrification process for inorganic wastewater containing 500 g/m(3) of NH(4)(+)-N was investigated. It was observed that spherical, pseudocubic and elliptical granules with a diameter of 346 microm were produced at the bottom of the reactor after 300 days. Denaturing gradient gel electrophoresis analysis revealed that Nitrosomonas-like bacteria were the dominant ammonia-oxidizing species in the granules. Many colonies of Nitrosomonas-like bacteria were found in the outer part of the granules based on the spatial distribution analysis by fluorescence in situ hybridization. By stepwise reduction of the hydraulic retention time, the ammonia removal rate of the AUFB reactor containing these nitrifying granules finally reached 1.5 kg-N/m(3)/day. Results suggested that the use of granules realizes the retention of a large amount of nitrifying bacteria in the reactor, which guarantees a highly efficient nitrification.

Ammonia↗
PubMed2003

Nitrogen removal characteristics and biofilm analysis of a membrane-aerated biofilm reactor applicable to high-strength nitrogenous wastewater treatment.

A membrane-aerated biofilm reactor (MABR) capable of simultaneous nitrification and denitrification in a single reactor vessel was developed to investigate the characteristics of nitrogen removal from high-strength nitrogenous wastewater, and biofilm analysis using microelectrodes and the fluorescence in situ hybridization (FISH) technique was performed. Mean removal percentages of total organic carbon (TOC) and nitrogen were 96% and 83% at removal rates of 5.76 g-C m(-2) d(-1) and 4.48 g-N m(-2) d(-1), respectively. For stable removal efficiency, constant washing of the biofilm was needed. Dissolved oxygen microelectrode measurement revealed that the biofilm thickness was about 1600 microm, and that oxygen penetrated about 300 to 700 microm, from the outer surface of the membrane. Furthermore, FISH analysis revealed that ammonia-oxidizing bacteria (AOB) were located near the outer surface of the membrane, whereas other bacteria were located from the inner to the outer part of the biofilm. Combining these results demonstrated that simultaneous nitrification and denitrification occurred in the biofilm of the MABR system. In addition, stoichiometric analysis revealed that after 130 d(-1), the free ammonia (FA) concentration ranged within the concentration causing inhibition of the growth of nitrite oxidizing bacteria (NOB) and that AOB consumed 86% of the oxygen supplied through the intra-membrane. These results indicate that nitrogen removal not via nitrate but via nitrite was mainly achieved in the MABR system.

Journal Article↗
PubMed2002

Characterization of denitrifying phosphate-accumulating organisms cultivated under different electron acceptor conditions using polymerase chain reaction-denaturing gradient gel electrophoresis assay.

To investigate the characteristics and the microbial diversity of denitrifying phosphate-accumulating organisms (DNPAOs) that are capable of conducting enhanced biological phosphorus removal (EBPR) using nitrate as electron acceptor, three sequencing batch reactors were operated under three different electron acceptor conditions, i.e., only oxygen, oxygen together with nitrate and only nitrate. Based on the chemical analysis concerning the biochemical transformation of each reactor, it was found that phosphate-accumulating organisms responsible for EBPR consisted of at least three populations including DNPAOs, and that the microbial community structure was changed according to the electron acceptor conditions. Also, the sludge cultivated with oxygen together with nitrate showed a drastic increase in the amount of phosphorus uptake under anoxic conditions, which suggested that a proportion of DNPAOs capable of utilizing nitrate under aerobic conditions were present. On the other hand, the change in microbial community structure depending on the type of electron acceptor was demonstrated by the analysis of the results of denaturing gradient gel electrophoresis of polymerase chain reaction-amplified 16S ribosomal DNA fragments. It was found that the bacteria commonly contained in all the reactors were Rhodocyclus sp. (96% identity) and Dechlorimonas sp. (97% identity) that belonged to the beta subclass of Proteobacteria on the basis of the analysis of the sequence excised from DGGE bands and the determination of phylogenetic affiliation. However, only the presence of Rhodocyclus sp. in all the reactors was demonstrated by fluorescent in situ hybridization analysis.

Bacteria↗