Michihiko Ike

Kitasato University, Edo, Tōkyō, Japan

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Publications (211)376.34 Total impact

  • Kazuichi Isaka · Makiko Udagawa · Kazunari Sei · Michihiko Ike ·
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    ABSTRACT: A pilot-scale (120L) bioreactor system using a gel carrier-entrapped pure bacterial strain, Afipia sp. strain D1, capable of degrading 1,4-dioxane as a sole carbon and energy source was constructed and applied to treat real industrial wastewater containing 1,4-dioxane from a chemical factory. Although the wastewater not only contained high concentrations of 1,4-dioxane but also considerable amounts of other organic compounds (73mg-TOCL(-1) on average), the bioreactor could efficiently remove 1,4-dioxane without significant inhibitory effects. The reactor startup could be completed within approximately 1 month by increasing the 1,4-dioxane loading rate (0.09-0.47kg-dioxanem(-3)d(-1)) in a stepwise manner. Effective 1,4-dioxane removal was stably maintained for 3 months with an influent 1,4-dioxane of 570-730mgL(-1), giving an average effluent concentration and removal rate of 3.4mgL(-1) and 0.46kg-dioxanem(-3)d(-1), respectively. A 1,4-dioxane loading fluctuation between 0.14 and 0.72kg-dioxanem(-3)d(-1) did not significantly affect its removal, and more than 99% removal efficiency was constantly maintained. The Monod model could well describe the relationship between the effluent 1,4-dioxane concentration and 1,4-dioxane removal rates of the bioreactors, showing that the half-saturation constant (Ks) was 28mgL(-1).
    Journal of hazardous materials 11/2015; 304:251-258. DOI:10.1016/j.jhazmat.2015.10.066 · 4.53 Impact Factor
  • Zhen Bi · Masashi Takekawa · Giri Park · Satoshi Soda · Sen Qiao · Michihiko Ike ·
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    ABSTRACT: A mathematic model was developed for describing the nitrogen and organic carbon removal via the simultaneous anaerobic ammonium oxidation (anammox) and heterotrophic denitrification (SAD) process. The model considered anammox bacteria, heterotrophic denitrifying bacteria, ammonium, nitrite, nitrate, and readily biodegradable carbon. The model parameters were calibrated by using the experimental data in the single batch reactors inoculated with anammox sludge of 190 mg-VSS/L and activated sludge of 110 or 220 mg-VSS/L for treating wastewater containing ammonium of 30 mg-N/L and nitrate of 40 mg-N/L. The rapid depletion of nitrate and acetate as the sole carbon source were observed in the reactor. Subsequently, the temporarily accumulated nitrite was removed with ammonium. The initial C/N ratio of 1.5–2.0 and the population ratio of heterotrophic denitrifying bacteria to anammox bacteria within 0.3–0.4 were suitable conditions for the batch SAD process. The sensitivity analysis of kinetic parameters revealed that the most influential parameters for the nitrogen and organic carbon removal were the half-saturation constants for nitrite of heterotrophic bacteria and anammox bacteria and the anoxic reduction factors of heterotrophic bacteria on the nitrate-reducing rate and the nitrite-reducing rate, which closely associated with nitrite accumulation in the SAD process.
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    ABSTRACT: For evaluating duckweed biomass as a bioresource, the specific growth rate and the chemical constituents of duckweed of four kinds were investigated. Spirodela polyrrhiza, Lemna minor, Wolffia arrhiza, and Wolffia globosa commonly showed high specific growth rates of 0.22–0.30 d−1 with initial concentrations of nitrogen >3.0 kg m−3 and phosphorus >5.0 kg m−3. All duckweeds had high sugar contents greater than 300 g kg−1 of dry mass. Especially, vegetative fronds of W. globosa showed the highest sugar content of 410 g kg−1 of dry mass. The duckweed biomass was pretreated easily by heating at 121 °C for saccharification using α-amylase and amyloglucosidase. The ethanol yield of W. globosa biomass in the simultaneous saccharification and fermentation (SSF) using the enzymes and dry yeast was 170 g kg−1 of dry mass, whereas the succinate yield in the SSF using the enzymes and Actinobacillus succinogenes was 200 g kg−1 of dry mass. The production rates of ethanol and succinate from the W. globosa biomass were estimated as 0.58 kg m−2 y−1 and 0.68 kg m−2 y−1, respectively. The biomass of duckweed, with its high growth rate and high starch content, can be an excellent renewable feedstock for the production of ethanol and succinate as building block chemicals for the replacement of petrochemicals.
    Biomass and Bioenergy 10/2015; 81:364-368. DOI:10.1016/j.biombioe.2015.07.020 · 3.39 Impact Factor
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    ABSTRACT: We examined the effect of planting an emergent aquatic plant (Phragmites australis) on nitrogen removal from sediments using a 42-d pot experiment. The experimental pot systems comprised two types of sediments planted with and without young P. australis. Total nitrogen (total N), total dissolved N, and NH4-N in the sediments decreased markedly after planting. In contrast, those levels decreased only slightly in the unplanted sediments. The decrease in total N in the P. australis-planted sediments was 7 to 20 times those in the unplanted sediments. Abundances of bacterial 16S rRNA, archaeal 16S rRNA, ammonia-oxidizing bacterial ammonia monooxygenase (amoA), ammonia-oxidizing archaeal-amoA, and denitrifying bacterial nitrite reductase (nirK) genes increased significantly in sediments after planting. Phragmites australis appears to have released oxygen and created a repeating cycle of oxidizing and reducing conditions in the sediments. These conditions should promote mineralization of organic N, nitrification, and denitrification in the sediments. Phragmites australis absorbed bioavailable nitrogen generated by microbial nitrogen metabolism. During the 42-d period after planting, 31-44% of total N was removed by microbial nitrogen cycling, and 56-69% was removed via absorption by P. australis. These results suggest that planting P. australis can increase microbial populations and their activities, and that nitrogen removal can be accelerated by the combined functions of P. australis and microorganisms in the sediment. Thus, planting P. australis has considerable potential as an effective remediation technology for eutrophic sediments.
    Environmental Technology 07/2015; DOI:10.1080/09593330.2015.1074156 · 1.56 Impact Factor
  • Kazuichi Isaka · Makiko Udagawa · Yuya Kimura · Kazunari Sei · Michihiko Ike ·
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    ABSTRACT: A biological treatment system for 1,4-dioxane-containing wastewater was developed using the bacterium Afipia sp. D1, which can utilize 1,4-dioxane as the sole carbon source. Strain D1 was entrapped in a polyethylene glycol gel carrier to stably maintain it in a bioreactor, and continuous feeding tests were performed to treat model industrial wastewater containing 1,4-dioxane. 1,4-Dioxane removal activity rapidly increased soon after the start of feeding of influent with 400 mg/L 1,4-dioxane, and the volumetric removal rate reached 0.67 kg dioxane/m(3)/d on day 36 by a stepwise increase in loading. The start-up period of the 1,4-dioxane treatment reactor was approximately 1 month, and stable removal performance was subsequently achieved for more than 1 month. The average 1,4-dioxane effluent concentration and 1,4-dioxane removal efficiency were 3.6 mg/L and 99%, respectively, during stable operation. Further 1,4-dioxane degradation activity of the of the gel carrier was characterized in batch experiments with respect to temperature. The optimum temperature for 1,4-dioxane treatment was 31.7°C, and significant removal was observed at a temperature as low as 6.9°C. The apparent activation energy for 1,4-dioxane degradation was estimated to be 47.3 kJ/mol. This is the first report of the development of a 1,4-dioxane biological treatment system using gel entrapment technology. Copyright © 2015 [The Author/The Authors]. Published by Elsevier B.V. All rights reserved.
    Journal of Bioscience and Bioengineering 07/2015; DOI:10.1016/j.jbiosc.2015.06.006 · 1.88 Impact Factor
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    ABSTRACT: Bacillus selenatarsenatis sp. nov. strain SF-1T is a promising agent for bioremediation of environments contaminated with selenium and arsenic. Here, we report the draft genome sequence of this strain.
    Genome Announcements 01/2015; 3(1). DOI:10.1128/genomeA.01466-14
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    Tadahiko Gyobu · Masao Inoue · Satoshi Soda · Michihiko Ike ·
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    ABSTRACT: This study elucidated the energy budget in wastewater treatment streams at Tsumori, Ichioka, and Chishima wastewater treatment plants (WWTPs) in Osaka. At Tsumori WWTP, the primary sludge produced in primary settling tanks and excess sludge produced in secondary settling tanks of the three WWTPs were collected and then digested anaerobically to biogas for cogeneration. The energy content of raw sewage at Tsumori WWTP was 4.3 kJ/L. Those at Ichioka and Chishima WWTPs were 2.1 kJ/L. The respective energy contents of primary sludge of Tsumori, Ichioka, and Chishima WWTPs were 16.3, 7.6, and 10.2 kJ/g. Those of excess sludge were 14.6, 8.3, and 9.8 kJ/g, respectively. The total calorific inflow to the three WWTPs was 1.1 × 109 kJ/d. About 40% and 30% of the total calorific energy respectively becomes primary sludge and excess sludge. The remaining 30% is consumed in the aeration tanks. About 30 - 40% the total calorific energy is recovered as biogas by anaerobic digestion, which produces electricity at 1.6 × 108 kJ/d, corresponding respectively to 47% and 33% of the electricity consumption of Tsumori WWTP and the three WWTPs.
    Journal of Water and Environment Technology 01/2015; 13(1):89-97. DOI:10.2965/jwet.2015.89
  • Yuka OGATA · Shohei GODA · Tadashi TOYAMA · Kazunari SEI · Michihiko IKE ·

    Journal of Japan Society on Water Environment 01/2015; 38(5):139-147. DOI:10.2965/jswe.38.139
  • Masashi Takekawa · Giri Park · Satoshi Soda · Michihiko Ike ·
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    ABSTRACT: This study investigated nitrogen removal by the simultaneous anaerobic ammonium oxidation (anammox) and heterotrophic denitrification (SAD) process in a sequencing batch reactor (SBR) inoculated with suspended activated sludge and immobilized anammox sludge at various total organic carbon/nitrate (C/N) ratios. Synthetic wastewater containing nitrate 100 mg-N L−1, ammonium 70 mg-N L−1, and acetate 50-250 mg-C L−1 was fed to the SBR. Nitrite reduced from nitrate by heterotrophic denitrification was accumulated and removed with ammonium in each cycle operation of the SBR. The SAD process removed nitrate and ammonium effectively (T-N removal, 58-94%) by the high anammox contribution (ca. 80-100%) under low C/N ratios (0.5-1.0). At high C/N ratios of 1.2-2.5, the SAD process maintained T-N removal 67-79% with predominance of heterotrophic denitrification instead of anammox reaction. Results demonstrated that the SAD process performs high nitrogen removal effectively from wastewater with widely different C/N ratios.
    Bioresource Technology 12/2014; 174. DOI:10.1016/j.biortech.2014.10.021 · 4.49 Impact Factor
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    ABSTRACT: AimsTo clarify the polyhydroxyalkanoate (PHA) accumulation potential and the PHA-accumulating microbial community structure in activated sludge in municipal wastewater treatment plants (WWTPs) and to identify their influential factors.Methods and ResultsNine activated sludge samples were collected from municipal WWTPs employing various biological treatment processes. In acetate-fed 24-h batch experiments under aerobic and nitrogen- and phosphorus-limited conditions, polyhydroxybutyrate (PHB) content of activated sludge increased from 0–1.3 wt% to 7.9–24 wt%, with PHB yields of 0.22–0.50 C-mol 3-hydroxybutyrate (C-mol acetate)‒1. Microbial community analyses found that activated sludge samples that accumulated >20 wt% of PHB after 24-h PHA accumulation experiments had >5.0×108 copies/g-mixed liquor suspended solid of phaC genes.Conclusions Results indicated that (i) activated sludge in municipal WWTPs can accumulate up to approximately 20 wt% of PHA without enrichment processes, (ii) PHA accumulation potential of activated sludge varied depending on the operational conditions (treatment processes) of WWTPs, and (iii) phaC gene number can provide a simple indication of PHA accumulation potential.Significance and Impact of StudyThis is the first study to compare the PHA accumulation potential and PHA-accumulating microbial communities in activated sludge of various treatment processes. Our findings may be useful for enhancing the resource recovery potential of wastewater treatment systems.This article is protected by copyright. All rights reserved.
    Journal of Applied Microbiology 11/2014; 118(1). DOI:10.1111/jam.12683 · 2.48 Impact Factor
  • Hiroyuki Ayano · Masashi Kuroda · Satoshi Soda · Michihiko Ike ·
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    ABSTRACT: Cadmium selenide (CdSe) was synthesized by Pseudomonas aeruginosa strain RB in a culture containing lactic acid as a carbon source, 1 mM selenite, and 1 mM cadmium under various conditions. High purity (1.02-1.16 of the atomic ratio of Se to Cd) and efficient synthesis of biogenic CdSe nanoparticles were observed at 25-30°C, 0.05-10 g L(-1) NaCl, and neutral pH conditions compared with other tested conditions. However, the size and shape of synthesized CdSe nanoparticles were not changed by changing culture conditions. The contents of S and Se in the particles respectively increased under alkaline and weak acidic conditions. Furthermore, high temperature (>37°C), high salinity (>10 g L(-1) NaCl), and alkaline pH affected the CdSe-synthesizing rate by strain RB. This report is the first optimizing the culture conditions for synthesizing biogenic CdSe nanoparticles in a batch processing. Copyright © 2014. Published by Elsevier B.V.
    Journal of Bioscience and Bioengineering 10/2014; 119(4). DOI:10.1016/j.jbiosc.2014.09.021 · 1.88 Impact Factor
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    ABSTRACT: Because of heavy dependence on groundwater for drinking water and other domestic use, microbial contamination of groundwater is a serious problem in the Kathmandu Valley, Nepal. This study investigated comprehensively the occurrence of pathogenic bacteria in shallow well groundwater in the Kathmandu Valley by applying DNA microarray analysis targeting 941 pathogenic bacterial species/groups. Water quality measurements found significant coliform (fecal) contamination in 10 of the 11 investigated groundwater samples and significant nitrogen contamination in some samples. The results of DNA microarray analysis revealed the presence of 1-37 pathogen species/groups, including 1-27 biosafety level 2 ones, in 9 of the 11 groundwater samples. While the detected pathogens included several feces- and animal-related ones, those belonging to Legionella and Arthrobacter, which were considered not to be directly associated with feces, were detected prevalently. This study could provide a rough picture of overall pathogenic bacterial contamination in the Kathmandu Valley, and demonstrated the usefulness of DNA microarray analysis as a comprehensive screening tool of a wide variety of pathogenic bacteria.
    Current Microbiology 08/2014; 70(1). DOI:10.1007/s00284-014-0681-x · 1.42 Impact Factor
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    ABSTRACT: A novel DNA microarray analysis targeting key functional genes involved in most nitrogen cycling reactions was developed to comprehensively analyze microbial populations associated with the nitrogen cycle. The developed microarray contained 876 oligonucleotide probes based on the nucleotide sequences of the nif, amo, hao/hzo, nap, nar, nirK, nirS, nrf, cnor, qnor and nos genes. An analytical method combining detection by the designed microarray with whole community genome amplification was then applied to monitor the nitrogen cycling microorganisms in river water and wastewater treatment sludge samples. The developed method revealed that nitrogen cycling microorganisms in river water appeared to become less diverse in response to input of effluent from municipal wastewater treatment plants. Additionally, the nitrogen cycling community associated with anaerobic ammonium oxidation and partial nitrification reactors could be reasonably analyzed by the developed method. However, the results obtained for two activated sludge samples from municipal wastewater treatment plants with almost equivalent wastewater treatment performance differed greatly from each other. These results suggested that the developed method is useful for comprehensive analysis of nitrogen cycling microorganisms, although its applicability to complex samples with abundant untargeted populations should be further examined.
    World Journal of Microbiology and Biotechnology 08/2014; 30(11). DOI:10.1007/s11274-014-1718-9 · 1.78 Impact Factor
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    Hiroyuki Ayano · Masashi Kuroda · Satoshi Soda · Michihiko Ike ·
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    ABSTRACT: Pseudomonas aeruginosa strain RB is a bacterium capable of synthesizing cadmium selenide (CdSe) nanoparticles and was isolated from a soil sample. Here, we present the draft genome sequence of P. aeruginosa strain RB. To the best of our knowledge, this is the first report of a draft genome of a CdSe-synthesizing bacterium.
    Genome Announcements 05/2014; 2(3). DOI:10.1128/genomeA.00368-14
  • Kurumi Hashimoto · Masami Matsuda · Daisuke Inoue · Michihiko Ike ·
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    ABSTRACT: To elucidate the bacterial community dynamics in a full-scale wastewater treatment plant (WWTP) and the relatedness among bacterial communities in the influent, effluent and sludge, the structure and metabolic ability of the bacterial community throughout a full-scale WWTP employing a conventional activated sludge process was investigated during a period of 10 months. The bacterial community structure was analyzed by terminal-restriction fragment length polymorphism targeting eubacterial 16S rRNA genes, while a Biolog assay was applied to assess the metabolic ability of the activated sludge. Influent bacterial community structure was generally stable. In contrast, the bacterial community structure in the effluent was similar to that in the influent in some cases, while in other cases it was unique and differed greatly from that in the influent and sludge. These results suggest that temporal variations of the effluent bacterial community may be useful to predict the wastewater treatment performance and settleability of activated sludge. The bacterial community structure in the sludge was relatively stable and was rarely impacted by the influent populations. Biolog assay also revealed that activated sludge maintained a remarkably similar metabolic potential of organic compounds over time due to functional redundancy, in which the minor populations played a significant role.
    Journal of Bioscience and Bioengineering 01/2014; 118(1). DOI:10.1016/j.jbiosc.2013.12.008 · 1.88 Impact Factor
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    ABSTRACT: Activated sludge microbial communities of 12 membrane bioreactors (MBRs) treating domestic wastewater were characterized in terms of their bacterial phylogenic composition and organic metabolism using eubacterial 16S rRNA gene-based terminal-restriction fragment length polymorphism (T-RFLP) analysis and carbon-utilization tests (Biolog assay). The phylogenic microbial structure of MBR sludges differed considerably among samples, depending neither on influent characteristics nor on operational modes and conditions. Comparison of the microbial community structures of the 12 MBRs and 11 conventional processes characterized in a previous study indicated that MBRs and the conventional processes differ considerably in terms of phylogenic structure. Also, dominant bacteria in MBRs differed considerably from each other, although those in the conventional processes were similar. In contrast, the carbon-utilization profile of activated sludge samples of 8 among 12 MBRs and all conventional processes tested in the previous study were mutually similar, indicating that activated sludge communities possess similar biodegradation potential against organic pollutants even if the phylogenetic bacterial composition differs. Results also demonstrated that some MBR sludge samples have unique carbon-utilization profiles, suggesting that MBRs enrich bacterial populations with unique metabolic activity.
    Journal of Water and Environment Technology 01/2014; 12(2):99-107. DOI:10.2965/jwet.2014.99
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    ABSTRACT: A small system was developed for volume reduction of radiocesium-contaminated soils. Included in this system was a 100-L air-lift washing chamber, a coagulation tank, and a dewatering apparatus. Soil samples (137Cs 6.2×103 - 1.9×104 Bq/㎏) collected from a parking area in Iitate village, Fukushima Prefecture were put through this soil washing chamber. Results showed that 14-17% (dry weight) of the soil particles were ideally recovered with 75-86% of 137Cs (3.0×104 - 7.4×104 Bq/㎏).Soil samples collected from an area with bamboo bushes, showed that 53-55% of the soil particle's weight were recovered with 87-89% of 137Cs (3.0×104 - 7.4×104 Bq/㎏).Soil samples collected from a farm load and ditch in Kawauchi village (1.0×103 - 7.3×103 Bq/㎏) were treated by soil washing, coagulation, and dewatering in series. Results showed that 10-14% weight of the soil particles were recovered as dewatered cake (4.4×103 - 3.1×104 Bq/㎏) with only 43-46% of 137Cs. These results confirm soil-characteristic-dependency from the volume reduction efficiency of radiocesium-contaminated soils.
    01/2014; 43(12):729-738. DOI:10.5956/jriet.43.729
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    ABSTRACT: In order to investigate the possibility of simultaneous anammox and heterotrophic denitrification(SAD)as a novel nitrogen removal process, batch experiments for nitrogen removal from synthetic wastewater containing acetate, nitrate, and ammonium were conducted using a mixture of activated sludge and anammox sludge. It is suggested that anammox bacteria removed ammonium and nitrite reductively generated from nitrate by heterotrophic denitrifiers existing in the activated sludge. In the batch experiments with the acetate-C/nitrate-N ratios over 0.5, total nitrogen removal was higher than 90% by occurrence of SAD. These results suggest that the SAD process can efficiently remove nitrogen under a wide range of the C/N concentrations, especially under low C/N ratios.
    01/2014; 43(5):293-300. DOI:10.5956/jriet.43.293

  • 01/2014; 43(2):96-101. DOI:10.5956/jriet.43.96
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    ABSTRACT: Bacteria capable of synthesizing CdSe from selenite and cadmium ion were enriched from a soil sample. After repeated transfer of the soil-derived bacterial cultures to a new medium containing selenite and cadmium ion 42 times (during 360 days), an enrichment culture that can simultaneously remove selenite and cadmium ion (1 mM each) from the liquid phase was obtained. The culture's color became reddish-brown, indicating CdSe nanoparticle production, as confirmed by energy-dispersive x-ray spectra (EDS). As a result of isolation operations, the bacterium that was the most responsible for synthesizing CdSe, named Pseudomonas sp. RB, was obtained. Transmission electron microscopy and EDS revealed that this strain accumulated nanoparticles (10-20 nm) consisting of selenium and cadmium inside and on the cells when cultivated in the same medium for the enrichment culture. This report is the first describing isolation of a selenite-reducing and cadmium-resistant bacterium. It is useful for CdSe nanoparticle synthesis in the simple one-vessel operation.
    Journal of Bioscience and Bioengineering 11/2013; 117(5). DOI:10.1016/j.jbiosc.2013.10.010 · 1.88 Impact Factor

Publication Stats

3k Citations
376.34 Total Impact Points


  • 2015
    • Kitasato University
      • Department of Health Science
      Edo, Tōkyō, Japan
  • 1991-2015
    • Osaka University
      • • Graduate School of Engineering
      • • Division of Sustainable Energy and Environmental Engineering
      Suika, Ōsaka, Japan
  • 2009
    • Vietnam National University, Ho Chi Minh City
      Thành phố Hồ Chí Minh, Ho Chi Minh City, Vietnam