Noriko Tomioka

A single band does not always represent single bacterial strains in denaturing gradient gel electrophoresis analysis

DNA in a denaturing gradient gel electrophoresis (DGGE) band that could not be sequenced after recovery from the gel was cloned into a TA cloning vector and a library was constructed and then 13 clones randomly picked up from the library was sequenced. Although the excised DNA from the DGGE gel showed a single band, the library consisted of several different sequences phylogenetically. This phenomenon was also observed in several other DGGE bands. Therefore, this suggests that a single DGGE band does not always represent a single bacterial strain and a new bias for quantitative analyses based on band intensities has been identified.

Biogenic Phosphorus Compounds in Sediment and Suspended Particles in a Shallow Eutrophic Lake: A 31P-Nuclear Magnetic Resonance (31P NMR) Study

Differences in biogenic phosphorus (P) compounds between sediment and suspended particles in aquatic environments are important for understanding the mechanisms of internal P loading, but these differences are still unknown. We used solution-state (31)P-nuclear magnetic resonance spectroscopy ((31)P NMR) with NaOH-ethylenediaminetetraacetic extraction to detect the multiple P compounds in suspended particles and sediment in the eutrophic Lake Kasumigaura, including orthophosphate monoesters, orthophosphate diesters, pyrophosphate, and polyphosphate. We tested the hypothesis that there is a significant difference between these groups in suspended particles and sediment. Biogenic P other than orthophosphate was found in significantly higher proportions in suspended particles (74.3% of total P) than in sediment (25.6%). Orthophosphate monoesters were comparatively more abundant in suspended particles, as indicated by the ratio of orthophosphate diesters to monoesters (average, 0.31 for suspended particles; 1.05 for sediment). The compounds identified as orthophosphate monoesters by (31)P NMR spectroscopy originated mainly from phospholipids (α-glycerophosphate and β-glycerophosphate) and ribonucleic acid (RNA-P), whereas the orthophosphate diesters included mostly DNA (DNA-P). These results suggest that the dynamics of orthophosphate diesters, the production of DNA-P, or the degradation of phospholipids, play an important role in P cycling in Lake Kasumigaura.

Development of a treatment system for molasses wastewater: The effects of cation inhibition on the anaerobic degradation process

This study evaluated the process performance of a novel treatment system consisting of an acidification reactor, an upflow staged sludge bed (USSB) reactor, an upflow anaerobic sludge blanket reactor, and an aerobic trickling filter for the treatment of a high-strength molasses wastewater with a chemical oxygen demand (COD) of up to 120,000mg/L. The USSB operating at 35°C was capable of achieving an organic loading rate of 11kgCOD/m(3) day with a methane recovery of 62.4% at an influent COD of 120,000mg/L. The final effluent COD was 4520mg/L. The system was effective with regard to nitrification and sulfur removal. Fifty percent inhibition of the bacterial activity of the retained sludge by the cations was determined at 8gK/L for sucrose degradation, 16gK/L for sulfate reduction, and 12gK/L or 9gNa/L for acetoclastic methane production. Cation inhibition of anaerobic degradation reduced the process performance of the USSB.

Seasonal and longitudinal changes in copper and iron in surface water of shallow eutrophic Lake Kasumigaura, Japan

Abstract The concentrations of copper and iron in surface water of the eutrophic Lake Kasumigaura, the second largest lake in Japan, have been monitored at three sites monthly from April 1989 until March 1994. The metals were analyzed by a graphite furnace AAS after filtration with a 0.45-μm membrane filter. The concentrations of copper in the water were in the range 10 −9 to 5 × 10 −8 M and showed clear seasonal changes, being higher in summer and lower in winter. The concentrations of copper did not decrease on passage through the lake. The values of dissolved chemical oxygen demand (COD Mn ) showed a similar behavior, an interaction of copper in the lake water with organic matter was estimated. The concentration of copper in the lake became sometimes higher than the value of EC 50 for Microcystis , however, the metal forms stable complex species with organic matter and the toxic effect may be reduced. The concentrations of iron, on the other hand, showed wide variation, but no obvious seasonal change. The concentrations of iron decreased very markedly during flow of water through the lake.

High-rate treatment of molasses wastewater by combination of an acidification reactor and a USSB reactor.

A combination of an acidification reactor and an up-flow staged sludge bed (USSB) reactor was applied for treatment of molasses wastewater containing a large amount of organic compounds and sulfate. The USSB reactor had three gas-solid separators (GSS) along the height of the reactor. The combined system was continuously operated at mesophilic temperature over 400 days. In the acidification reactor, acid formation and sulfate reduction were effectively carried out. The sugars contained in the influent wastewater were mostly acidified into acetate, propionate, and n-butyrate. In addition, 10–30% of influent sulfur was removed from the acidification reactor by means of sulfate reduction followed by stripping of hydrogen sulfide. The USSB achieved a high organic loading rate (OLR) of 30 kgCOD m−3 day−1 with 82% COD removal. Vigorous biogas production was observed at a rate of 15 Nm3 biogas m−3 reactor day−1. The produced biogas, including hydrogen sulfide, was removed from the wastewater mostly via the GSS. The GSS provided a moderate superficial biogas flux and low sulfide concentration in the sludge bed, resulting in the prevention of sludge washout and sulfide inhibition of methanogens. By advantages of this feature, the USSB may have been responsible for achieving sufficient retention (approximately 60 gVSS L−1) of the granular sludge with high methanogenic activity (0.88 gCOD gVSS−1 day−1 for acetate and as high as 2.6 gCOD gVSS−1 day−1 for H2/CO2). Analysis of the microbial community revealed that sugar-degrading acid-forming bacteria proliferated in the sludge of the USSB as well as the acidification reactor at high OLR conditions.

Bacterial contribution to dissolved organic matter in eutrophic Lake Kasumigaura, Japan

ABSTRACT Incubation experiments using filtered waters from Lake Kasumigaura were conducted to examine bacterial contribution to a dissolved organic carbon (DOC) pool. Bacterial abundance, bacterial production, concentrations of DOC, total dissolved amino acids (TDAA), and total dissolved neutral sugars (TDNS) were monitored during the experiments. Bacterial production during the first few days was very high (20 to 35 μg C liter−1 day−1), accounting for 40 to 70% of primary production. The total bacterial production accounted for 34 to 55% of the DOC loss during the experiment, indicating high bacterial activities in Lake Kasumigaura. The DOC degradation was only 12 to 15%, whereas the degradation of TDAA and TDNS ranged from 30 to 50%, suggesting the preferential usage of TDAA and TDNS. The contribution of bacterially derived carbon to a DOC pool in Lake Kasumigaura was estimated using d-amino acids as bacterial biomarkers and accounted for 30 to 50% of the lake DOC. These values were much higher than those estimated for the open ocean (20 to 30%). The ratio of bacterially derived carbon to bulk carbon increased slightly with time, suggesting that the bacterially derived carbon is more resistant to microbial degradation than bulk carbon. This is the first study to estimate the bacterial contribution to a DOC pool in freshwater environments. These results indicate that bacteria play even more important roles in carbon cycles in freshwater environments than in open oceans and also suggests that recent increases in recalcitrant DOC in various lakes could be attributed to bacterially derived carbon. The potential differences in bacterial contributions to dissolved organic matter (DOM) between freshwater and marine environments are discussed.

Dynamics of particulate phosphorus in a shallow eutrophic lake.

We tested the hypothesis that in shallow, eutrophic Lake Kasumigaura, the concentration of particulate phosphorus (PP) is controlled by biogenic P (P in living or dead phytoplankton and bacterial cells), rather than by resuspension of inorganic P in sediment. Increases in wind velocity and turbidity were associated with bottom shear stress exceeding the critical value for the lake (τc=0.15Nm(-2)); this increased turbidity was due to sediment resuspension. However, concentrations of PP; HCl-extractable, reactive P in PP (P-rP); and HCl-extractable, non-reactive P in PP (P-nrP) were not correlated with wind velocity (PP vs. wind velocity: r=0.40, p>0.05). Rather, the P-nrP concentration accounted for approximately 79% of PP, and the concentrations of PP, P-rP, and P-nrP were correlated with the particulate organic carbon (POC) concentration (POC vs. PP: r=0.90, p<0.01; POC vs. P-rP: r=0.82, p<0.01; POC vs. P-nrP: r=0.86, p<0.01). In our (31)P nuclear magnetic resonance spectroscopy results, mononucleotides accounted for the largest proportion among the detected P compound classes. In addition, concentrations of mononucleotides, orthophosphate, and pyrophosphate were significantly higher in samples with high POC concentrations, whereas the DNA-P concentration was not. These results suggest that biogenic P affects PP concentrations more strongly than does sediment resuspension, and the production of biogenic P creates a pool of mononucleotides, a class of easily degradable P, even in shallow, eutrophic Lake Kasumigaura.

Recovery of 137Cs by a bioaccumulation system using Rhodococcus erythropolis CS98

Abstract With a bioaccumulation system using Rhodococcus erythropolis CS98 for recovery of cesium-137, we found that 137 Cs accumulated when a carbon source was added for energy supply. With the addition of ammonium acetate as the carbon source, almost all the 137 Cs from deionized water was recovered using a cell suspension of 1 g/ l with incubation for 24 h. Cell damage by radioactivity was not detected during the 24 h period. 137 Cs recovery from river water samples was lower than that from deionized water, especially from river water with a very high potassium concentration (the lower reaches of the Sakura River: potassium concentration=4.3 mg/ l ). When 3.9 mg/ l of potassium was added to a deionized water sample, 137 Cs recovery decreased to 35% of that without potassium addition, suggesting that the potassium concentration is a critical factor for 137 Cs recovery. We conclude that a bioaccumulation system with a semipermeable membrane tube, such as is described in this paper, is feasible for the recovery of radioactive cesium from fresh waters.

Effect of irradiance and temperature on photosynthetic activity of the cyanobacterium Microcystis spp.

Abstract The effect of irradiance and temperature on the photosynthetic activity of strains of three Microcystis species, M. aeruginosa K‐5, M. wesenbergii K‐3A, and M. viridis N‐l were investigated. At 25∘C, maximum photosynthetic activities (P max) of the K‐5, K‐3A and N‐l strains were observed under 240, 240 and 60 μE.m‐2 .s‐1, respectively. The Pmax values on a dry weight cell basis, were 4.1, 2.9 and 0.9 μ mol O2. mg dry weight‐1 .h‐1, respectively. The N‐l strain was adapted to a lower irradiance than the K‐5 and K‐3A strains. On a chlorophyll α basis, the Pmax of K‐5, K‐3A and N‐1 strains at 25°C were similar at 210, 240 and 210 μ mol O2.mg chl.a‐1.h‐1, respectively. Thus the lower Pmax per unit dry weight for strain N‐1 seems to be due to its lower chlorophyll a content. The optimum temperature of photosynthetic activity for the K‐5, K‐3A and N‐1 strains were observed at 35°C, 35°C and 20–30°C, respectively. Photosynthetic rates at the optimal temperature were 6.0, 3.8 and 1.9–2.0 μ mol O2. mg dry...

Direct evidence for the alteration of 13C natural abundances during early diagenesis in Lake Kasumigaura, Japan

In sediment trap materials or suspended particulate organic matter, δ13C values must be averaged over at least several years to determine δ13C shifts during sedimentation. To overcome this problem, we studied isotopic modification of sedimentary organic carbon during early diagenesis in sediment samples collected intermittently from a site at the center of Lake Kasumigaura, Japan, over a period of nearly 30 years, beginning in 1979. We examined the degree of apparent isotope discrimination by comparing long-term changes in the carbon isotope composition of the surface sediment (top 2 cm) with the isotope composition profile from 0 to 15 cm. The downcore C isotope composition profile was close to the values calculated from the long-term changes in the isotope composition of the surface sediment, suggesting that the sedimentary carbon isotope composition was generally conserved (±0.6‰) during early diagenesis (up to 30 years). However, at greater core depths, significant 13C enrichment of up to 1.5‰ was sometimes observed, especially in the periods of relatively oxidative conditions.