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Volume 44 (2008)
- Issue 4 Pages 175-
- Issue 3 Pages 121-
- Issue 2 Pages 57-
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Volume 44, Issue 4
Displaying 1-6 of 6 articles from this issue
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ORIGINALS
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MD SHAFIQUZZAMAN, IORI MISHIMA, JUN NAKAJIMAArticle type: ORIGINALS
2008 Volume 44 Issue 4 Pages 175-185
Published: 2008
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSHybrid methods for arsenic removal from synthetic groundwater were investigated in this study. Batch study showed that As(III) removal was first-order at high Fe(0) shavings concentration and approached zero-order at low concentration. It was suggested that As(III) was removed by surface precipitation and adsorption processes. A single Fe(0) shavings column experiment was conducted for As(III) removal and the experimental data were evaluated by the Thomas and Yan adsorption models. As(III) removal capacity of Fe(0) shavings estimated by the Thomas model (11.3 mg/g) and Yan models (10.8 mg/g) were closed to the values calculated from the experimental data (10.3 mg/g). Two types of hybrid column filtration methods (Hybrid 1 and Hybrid 2) were conducted to evaluate the processes with regard to the applicability and remedial performance of As(III). Hybrid 1 was bacterial column (BC) filtration followed by Fe(0) shavings column filtration (MC), while Hybrid 2 was MC followed by BC. Results showed that As(III) was removed to less than 10 μg/l in Hybrid 1 but the effluent Fe concentration was higher (> 0.5 mg/l). By contrast, both As and Fe were removed to less than 10 μg/l and 0.3 mg/l, respectively in Hybrid 2. The MC columns data of Hybrid 1 and Hybrid 2 were examined by the Thomas and Yan models. As(III) removal capacity was increased in Hybrid 2 MC due to the presence of Fe(II) in the synthetic groundwater. Accordingly, it was suggested that the hybrid methods would be effective processes to remove As(III) from highly contaminated groundwater.View full abstractDownload PDF (855K) -
DAISUKE YAZAKI, YASUHIRO NAKAMURA, RYOICHI KUSUMOTO, ICHIRO TESHIBA, Y ...Article type: ORIGINALS
2008 Volume 44 Issue 4 Pages 187-193
Published: 2008
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSA novel aerobic wastewater treatment method by using open channel filter bed equipped with aspiratory microscopic-bubble-producing nozzle (AMBN－OFB) was developed and investigated for the applicability to piggery wastewater treatment. The aspiratory microscopic-bubble-producing nozzle supplied oxygen efficiently to the piggery wastewater and kept the DO concentration at more than 3.0 mg/l without other aerators. The piggery wastewater containing more than 500 mg/l BOD and 1000 mg/l SS was properly treated by AMBN-OFB, and 90 % of both BOD and SS were removed at a HRT of 5 days in the field experiment. Turbidity was decreased from 1000 to 50 and bad odor was also disappeared within 3 days. There was no trouble of the clogging in the bed during experimental period of 6 months (total 12 times of batch experiments). The oxidation of NH4－N to NO2－N was observed, but NO3－N production was only a little, which suggested that the adverse effect of high concentration of free ammonia on nitrite oxidizing bacteria (NOB). AMBN－OFB is expected as a simple and easy-operative wastewater treatment method, especially for the wastewater from a small-scale livestock farm.View full abstractDownload PDF (1241K) -
MOTOO UTSUMI, KEISHI KAMEYAMA, KUNIHIRO OKANO, NORIO SUGIURAArticle type: ORIGINALS
2008 Volume 44 Issue 4 Pages 195-202
Published: 2008
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSMicrocystin, a hepatotoxin produced by cyanobacteria Microcystis species, is biosynthesized nonribosomally by a multifunctional enzyme complex. The enzyme is composed of peptide synthetase and polyketide synthase coded by the mcy gene cluster. Especially, mcyB and mcyD are representative for microcystin biosynthesis genes of peptide synthetase and polyketide synthase, respectively. The effect of cell growth or cell cycle on the toxin biosynthesis of Microcystis has not been clarified. The purpose of this study is to elucidate when the microcystins are synthesized and accumulated in the cell and how intracellular microcystins act in the cell. We examined the transcript levels of mcyB and mcyD under nitrate starved synchronous culture of axenic strain Microcystis viridis NIES－102. Both the gene transcript levels could be observed with the proportion of the cells in S－phase. Then, microcystins were highly contained when the proportion of G2/M－phase cells was the highest value in culture medium. Furthermore, it was indicated that pyrogallol, which was an allelopathic compound produced by macrophytes such a genus Myriophyllom, inhibited the expression of the mcyD genes in M. viridis. These results suggested that the microcystin biosynthesis were closely correlated with the cell cycle in the toxin-producing cyanobacteria.View full abstractDownload PDF (744K) -
TAKAHIRO SEKIKAWA, YU KAWASAKI, YASUTO KATAYAMA, KEISUKE IWAHORIArticle type: ORIGINALS
2008 Volume 44 Issue 4 Pages 203-208
Published: 2008
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSCryptosporidium is a protozoan that causes gastrointestinal disease. Extraction of DNA from Cryptosporidium oocysts is complicated due to the hard outer wall. Generally, the oocyst DNA is extracted with proteinase K in a lysis buffer containing sodium dodecyl sulfate (SDS). However, SDS, being a strong inhibitor of Taq and Bst DNA polymerases, needs to be removed before PCR and Loop-mediated isothermal amplification (LAMP), respectively. In this study, we evaluated the ability of nonionic surfactants to suppress the inhibition of Bst DNA polymerase by anionic surfactants such as SDS, in the LAMP method. The primer set for LAMP was designed from the polythreonine gene of C. parvum. Bst DNA polymerase used in LAMP was inhibited by 0.01% of SDS or sodium dodecyl benzene sulfonate (SDBS), but this inhibition was suppressed by the addition of 5% of Triton X－100 or Tween 20. Subsequently, we applied this suppression of Bst DNA polymerase inhibition to C. parvum DNA detection using the LAMP method and succeeded in detecting DNA from ten oocysts in the presence of 0.01% SDS or SDBS.View full abstractDownload PDF (1227K) -
CHIE SATO, YUKIO KAWAUCHI, ASUKA NASUNO, MASATO IMAZATO, ICHIRO OKEI, ...Article type: ORIGINALS
2008 Volume 44 Issue 4 Pages 209-215
Published: 2008
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSRecently, lakes and reservoirs have been still entrophicated with the discharge of agricultural and domestic waste water inflow. Even in drinking water treatment plant that has kept good water quality source condition, musty-odor problem has been frequently occurred. Musty-odor compounds are mainly 2－methyl－iso－borneol (2－MIB) and geosmin, produced by some filamentous cyanobacteria and actinomycetes in aquatics. In 2002 and 2004, the Ibaraki, Lake Kouzogawa experienced musty-odor occurrence with high concentration of 2－MIB, associating with the growth of Phormidium sp. This research is aimed to clarify the correlation between the occurrence of musty-odor compounds and the dynamics of their causative microorganisms. It was revealed that the lake was mesotrophic and phosphorus restriction, and thermocline was unformed through the years; however dissolved oxygen was decreased nearly on the sediment surface in the lake in summer. In the summer of 2006, 5ng/l of geosmin, and in the autumn, over 10 ng/l of geosmin was detected. And from 2007 to 2008, the low concentration of geosmin was frequently observed. Then, the proliferated period of cyanobacteria which was suspected to produce musty-odor compounds didn’t coincide with the occurrence period of the musty-odor compounds. Therefore, it was indicated that cyanobacteria were not responsible for the occurrence of musty-odor compounds. Although actinomycetes always existed high density in the lake sediment relative to water column, its colony number changed by the depth and the season. Furthermore, there were many geosmin producing actinomycetes in the isolated colonies; consequently it was suggested that geosmin in water column of the lake was attributed to actinomycetes in the sediment from 2006 to 2008.View full abstractDownload PDF (1136K) -
HIROSHI MURAKAMI, TAKASHI KATO, AKIRA HONDAArticle type: ORIGINALS
2008 Volume 44 Issue 4 Pages 217-223
Published: 2008
Released on J-STAGE: March 10, 2018
JOURNAL FREE ACCESSAs part of the research for estimating the impact of nitrate on the safety of a repository for radioactive wastes, the isolation and characterization of nitrate-reducing bacteria in alkaline conditions were conducted. One microbial strain (No. 3－2) that showed nitrate-reducing activity at pH 10 was isolated from soil sample. On the basis of 16S rDNA sequence analysis and phylogenetic analysis, strain No. 3－2 was estimated to be a novel strain in the genus Bacillus.The isolated bacteria were studied to determine the optimal conditions in terms of temperature and pH for growth and concentration of electron receptor for nitrate reduction. As the results, optimal temperature for growth was 25 to 35 ℃ and optimal pH for growth was pH 9 to 10. This result suggested that strain No. 3－2 was an alkaliphilic bacteria. The strain No. 3－2 showed the best performance for nitrate reduction rates of 1.3×10–6 mmole-Nitrite/CFU/d under optimal condition at 25 ℃, pH 10 after 2 days cultivation.View full abstractDownload PDF (2426K)
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