A novel mesophilic and aerobic ammonia-oxidizing archaeon of the phylum , strain NM25, was isolated from coastal eelgrass zone sediment sampled in Shimoda (Japan). The cells were rod-shaped with an S-layer cell wall. The temperature range for growth was 20-37 °C, with an optimum at 30 °C.
View Article and Find Full Text PDFNitrous oxide (NO) is a powerful greenhouse gas; however, limited information is currently available on the microbiomes involved in its sink and source in seagrass meadow sediments. Using laboratory incubations, a quantitative PCR (qPCR) analysis of NO reductase (nosZ) and ammonia monooxygenase subunit A (amoA) genes, and a metagenome analysis based on the nosZ gene, we investigated the abundance of NO-reducing microorganisms and ammonia-oxidizing prokaryotes as well as the community compositions of NO-reducing microorganisms in in situ and cultivated sediments in the non-eelgrass and eelgrass zones of Lake Akkeshi, Japan. Laboratory incubations showed that NO was reduced by eelgrass sediments and emitted by non-eelgrass sediments.
View Article and Find Full Text PDFConcentrations of 18 elements, including Sb, In, Sn, and Bi, were measured in sediment cores from two pristine alpine lakes on Mount Hachimantai, northern Japan, representing the past 250 years. Vertical variations in concentrations are better explained by atmospheric metal deposition than by diagenetic redistribution of Fe and Mn hydroxide and organic matter. Anthropogenic metal fluxes were estimated from (210)Pb-derived accumulation rates and metal concentrations in excess of the Al-normalized mean background concentration before 1850.
View Article and Find Full Text PDFAlthough the emission of N(2) via anaerobic ammonium oxidation (anammox) is a key process in the elimination of nitrogenous compounds from aquatic environments, little information is available regarding its significance and the relevant microorganisms (anammox bacteria) in eutrophic freshwater lakes. In the present study, the anammox bacteria in the sediment of a eutrophic lake in Japan, Lake Kitaura, were examined using a (15)N-tracer technique to measure their potential anammox activity. Potential anammox activity was localized to the northern region of the lake where a stable supply of both NH(4)(+) and NO(3)(-) existed in the sediment.
View Article and Find Full Text PDFMangrove forests are common in subtropical regions, and have received considerable attention as vegetative buffers against anthropogenic N-loading. In this study, we investigated anaerobic ammonium oxidation (anammox) as one of potentially important microbial N-removing pathways in mangrove and shrimp pond sediment in Haiphong, Vietnam. Measurements with (15)N-labeled compounds demonstrated the occurrence of anammox in sediment of mangrove forest and a water channel connecting shrimp ponds to the sea in both 2005 and 2007, and of a semi-intensive shrimp pond in 2005.
View Article and Find Full Text PDFWe modified and tuned a commercial model of a gas chromatography/mass spectrometry (GC/MS) instrument to develop a simple and rapid method for the simultaneous quantification of a variety of gas species. Using the developed method with the newly modified instrument, gas species such as H(2), N(2), O(2), CO, NO, CH(4), CO(2), and N(2)O, which are common components of microbial metabolism, were accurately identified based on their retention times and/or mass-to-charge ratios (m/z) in less than 2.5 min.
View Article and Find Full Text PDFThis paper presents a quantitative investigation and analysis of anammox activity in sludge taken from biological swine wastewater treatment plants. An incubation experiment using a (15)N tracer technique showed anammox activity in sludge taken from 6 out of 13 plants with the rate ranging from 0.0036 micromol-N(2)/g-VSS/h to 3.
View Article and Find Full Text PDFIsotopes Environ Health Stud
September 2008
Dynamics of greenhouse gases (N(2)O and CH(4)) with the dry-wet cycle along with the variation of oxidation-reduction boundaries were investigated in the tropical wetland in monsoon Asia. It was clarified that the production of N(2)O and CH(4) was closely related to the development of a redox boundary in the Bang Nara River systems. An intermittent increase in N(2)O was observed at the beginning of the rainy season, when a large amount of easily decomposable organic matter was introduced into the river.
View Article and Find Full Text PDFThe relationship between chloroplast arrangement and diffusion of CO(2) from substomatal cavities to the chloroplast stroma was investigated in Arabidopsis thaliana. Chloroplast position was manipulated by varying the amount of blue light and by cytochalasin D (CytD) treatment. We also investigated two chloroplast positioning mutants.
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