Masatoshi Matsumura

Comparative Analysis of Bacterial Diversity in Freshwater Sediment of a Shallow Eutrophic Lake by Molecular and Improved Cultivation-Based Techniques

ABSTRACT Comparative analysis of bacterial diversity in freshwater sediment collected from a shallow eutrophic lake was performed by using 16S rRNA gene clone library and improved cultivation-based techniques. Our study demonstrated that the use of gellan gum as a gelling reagent instead of agar was more effective at increasing culturability, cultivating a diverse array of novel microbes, and reducing the gaps of the results between molecular and cultivation-based analyses.

Mercury removal from wastewater using porous cellulose carrier modified with polyethyleneimine

Abstract An adsorbent for heavy metal was synthesized by introducing polyethyleneimine (PEI) into porous cellulose carriers. Evaluations of synthesis results and adsorbent properties were conducted. Elementary analysis of the adsorbent revealed extensive crosslinking of PEI with the modified matrix. Batch adsorption tests showed the ability of cell-PEI to selectively remove mercury even at acidic regions. At low concentration ranges, mercury adsorption by cell-PEI can be interpreted by the Langmuir isotherm. With this model, an adsorbent capacity and Hg-ligand stability constant of approximately 288.0 mg g−1 and 12.91 mg−1, respectively, were obtained. From adsorption rate experiments, diffusivity of Hg in the carrier was found to be approximately equal to 7.30 × 10−14 m2 s−1. Extensive crosslinking of PEI chains that restricts ligand mobility was cited as the foremost factor contributing to these observed properties.

Nitrogen removal and N2O emission in a full-scale domestic wastewater treatment plant with intermittent aeration

Nitrous oxide (N2O) is emitted from wastewater treatment processes. It is known as a greenhouse gas that contributes to global warming (over 200 times more per molecule than carbon dioxide) and to the destruction of the ozone layer. It is therefore of great importance to develop technology that can suppress N2O emission. The effects of an anoxic period on N2O emission and nitrogen removal were investigated in an actual domestic wastewater treatment plant. When operated with intermittent aeration, most of the N2O was emitted into the atmosphere during the aerobic period. N2O emission from the intermittent process was estimated to be 0.43–1.89 g N2O person−1 year−1. Maintaining a dissolved oxygen (DO) concentration of over 0.5 mg l−1 during the aerobic period resulted in the complete conversion of the influent NH4-N to NO3-N and a 60-min anoxic period was sufficient for denitrification to be completed. The findings show that an optimum combination of aerobic and anoxic conditions and their suitable control are very important for improving nitrogen removal efficiency and controlling N2O emission.

Improved metal affinity of chelating adsorbents through graft polymerization

Modification of cellulose for heavy metal adsorption was conducted by the graft polymerization of glycidyl methacrylate utilizing ceric ammonium nitrate initiator, followed by the reaction with polyethyleneimine to introduce nitrogenous ligands. Infrared (IR) spectra of the reaction intermediates and products qualitatively revealed the presence of significant functional groups. Low amine to epoxide ratio (2 amines/epoxide) from elemental analysis of the products confirmed the occurrence of crosslinking between PEI and poly(GMA) side chain. Comparisons between metal adsorption isotherms of poly(CGMAPEI) adsorbent and cellulose-PEI, a previously synthesized adsorbent having extensive PEI crosslinking with the matrix, showed a higher metal affinity in the former. Based on these properties, an adsorbent structure model where ligands acquire an improved mobility was suggested. Optimization experiments further revealed that the metal affinity of the this adsorbent is affected by the amount of initiator during polymerization.

Differentiation of human promyelocytic leukemia cell line HL60 by microbial extracellular glycolipids

Microbial extracellular glycolipids, succinoyl trehalose lipid (STL), and mannosylerythritol lipid (MEL) inhibited the growth of a human promyelocytic leukemia cell line, HL60, and induced their morphological changes. The results of specific and nonspecific leukocyte esterase activities showed that STL induced monocytotic differentiation while MEL induced granulocytic differentiation. STL and MEL markedly increased common differentiation-associated characteristics in monocytes and granulocytes, such as nitroblue tetrazolium (NBT) reducing ability, expression of Fc receptors, and phagocytic activities in HL60 cells, respectively. Neither sugar moieties nor fatty acids in the free form, the individual components of STL and MEL, were effective at inducing the differentiation of HL60 cells. The induction of differentiation was not due to surface activities of STL and MEL on the basis of the complete ineffectiveness of the analogues tested. The composition of cell surface glycosphingolipids (GSL) changed such that the GM3/LacCer ratio increased in STL-treated cells, whereas it decreased in MEL-treated cells. HL60 cells treated with STL and MEL exhibited a significant decrease in the activity of the intracellular phospholipid- and Ca2+-dependent protein kinase (protein kinase C). Furthermore, the serine/threonine phosphorylations in intact HL60 cells were clearly inhibited by the presence of GM3 and MEL, but not by LacCer and STL. These results suggest that the differentiation-inducing activity of STL and MEL is not due to a simple detergent-like effect but due to a specific action on the plasma membrane. The inhibitory effect of STL on protein kinase activity was through increasing GM3, but MEL had a direct inhibitory effect.

Decolorization of molasses wastewater using an inorganic flocculant

Abstract The removal of molasses-derived melanoidin in alcohol distillery wastes was studied using a commercial inorganic flocculant with a chemical formula of [Fe2(OH)n(SO4)3-n/2]m. Decolorization yields of 32, 87 and 94% were obtained for fresh slops and for biodigester and lagooned effluents, respectively, at a flocculant dosage of 4% v/v. The reduction in total organic carbon (TOC) was 21% for fresh slops and averaged to more than 73% for the biodigester and lagooned effluents. The presence of relatively high amounts of fluoride ions affected the decolorization of fresh slops; supplementing CaO at a rate of 30 g/l improved the decolorization of the distillery slops, resulting to 93% color removal.

Flocculation of melanoidins induced by inorganic ions

Natural melanoidin in alcohol distillery effluent and synthetic melanoidin, which was prepared from glucose and glycine, showed similar elemental (CHON) compositions, spectroscopic properties and electrophoretic mobilities at various pH values. Optimal flocculation induced by FeCl3, AlCl3 or polyferric hydroxysulfate was obtained at a trivalent cation concentration of 0.04 M; excess flocculant caused color intensification of distillery effluents. Based on the electrical charge properties of melanoidins, a model is proposed for their flocculation and deflocculation induced by inorganic ions.

On-site nitrate removal of groundwater by an immobilized psychrophilic denitrifier using soluble starch as a carbon source

On-site denitrification of nitrate-contaminated groundwater was conducted at 15 degrees C using a facultative psychrophilic denitrifier (strain 47) immobilized on macro-porous cellulose carriers and utilizing soluble starch as a non-toxic carbon source. A C/N ratio of 2.5 to 3.0 and a P/N ratio of 0.05 to 0.10 were found to allow complete denitrification of the groundwater used in this study. Under these conditions, the long-term performance of the system (4 months) was examined by decreasing the HRT (hydraulic retention time) from 4 h to 0.25 h. The process was stable and 95 to 100% of the influent nitrogen (NO3-N ranging from 13.0 to 16.5 mgl(-1) was removed until an HRT of 0.75 h was reached. The maximum NO3-N removal rate was 0.46 kg-Nm(-3)d(-1) at an HRT of 0.75 h. Nitrogen removal efficiency of 99.5% at an HRT of 1 h was obtained with a C/N ratio 2.58, corresponding to 4.3 g of soluble starch per 1 g of NO3-N.

Production of micro-gel beads by a rotating disk atomizer

Abstract Micro-gel beads (200–1,200 μm in diameter) were produced by atomization of sodium alginate solution or a sodium alginate-perfluorocarbon mixture with a rotating disk. At any rotation speed of the disk (N) and low volumetric flow rate of the alginate solution (Q), direct drop formation was observed at the edge of the disk. However, with increases in the volumetric flow rate, there was a transition from the direct drop formation to a ligament type of disintegration. The length of the ligaments increased with an increase in Q. Although the diameter of the micro-gel beads showed a bimodal distribution with the number of satellite beads increasing with an increase in Q and a decrease in N, the volume percentage of the satellite beads was negligible. The mean volume diameter of the micro-gel beads (dv) was represented by a dimensionless equation: d v D = 22.4N We −0.43 N Re 0.08 N Z 0.07 , where D is the diameter of the disk, NWe, NRe and NZ are the Weber, Reynolds, and Ohnesorge numbers, respectively. By immobilizing viable bakers yeast cells in micro-gel beads 500 μm in diameter, the effectiveness factor for oxygen consumption at a DO concentration of 0.022 mol/m3 was 6 times higher, while the apparent Km value was 50% lower, than when they were immobilized in gel beads 3.2 mm in diameter.

Application of solvent extraction to ethanol fermentation

SummaryThe basic problems of applying solvent extraction to ethanol fermentation were investigated. The selection of solvents was based on the selectivity ratio, which was expressed as the ratio of the ethanol distribution coefficient to the water distribution coefficient. Solvents with high selectivity ratios of more than 50 were found mainly among the alcohols and esters. However, most of these solvents were toxic to ethanol-producing microorganisms. We tried to make a barrier to solvent molecules beneath the surface of gel beads immobilizing the cells as a protection against solvent toxicity. Porapack Q was found to be an effective barrier, and the ethanol production rate of immobilized cells protected with Porapack Q did not change event after the production of eight batches in medium saturated with sec-octanol, which was the most toxic solvent used in our experiments.