Isei Nakamura

Decolorization of Molasses Waste Water by a Thermophilic Strain, Aspergillus fumigatus G-2-6

We screened for fungi that can decolorize molasses melanoidin in the tropical zone and isolated some strains, mainly in the genus Aspergillus. Of these, strain No. G-2–6 was most active and was identical with Aspergillus fumigatus based on detailed morphological studies.This strain decolorized about 75% of a molasses melanoidin solution when the strain was cultivated on a glycerol-peptone medium at 45°C for 3 days with shaking. In successive decolorization reusing the mycelia, this strain had more than 60% of the melanoidin-decolorizing activity at the eighth replacement in the presence of 4% glycerol.Continuous decolorization of molasses melanoidin solution in a jar fermentor had an almost constant decolorization yield of about 70% at a dilution rate of 0.014 hr-1. At the same time, about 51 % of the chemical oxygen demand and 56% of the total organic carbon in the initial solution were removed. In contrast, continuous decolorization of non-dialyzed molasses melanoidin solution removed a little more chem...

Coimmobilization of Nitrosomonas europaea and Paracoccus denitrificans cells using polyelectrolyte complex-stabilized calcium alginate gel

Calcium alginate gel (CAG) that withstands phosphate ions in the medium was prepared by reinforcing a network structure of the gel with a polyelectrolyte complex (PEC) consisting of potassium poly(vinyl alcohol) sulfate and trimethylammonium glycol chitosan iodide. The PEC-stabilized CAG beads were used as a supporting matrix for the coimmobilization of Nitrosomonas europaea ATCC 25978 cells and Paracoccus denitrificans IFO 12442 cells. The coimmobilized cells were aerobically cultured on a medium containing 3 mM of phosphate ions, using (NH4)2SO4 as a substrate and ethanol as a carbon source. Ammonia was consumed without forming nitrite, indicating the concurrence of nitrification and denitrification in the same system. No breakage of the gel beads was observed during the cultivation. Repeated aerobic cultivation using a column packed with beads of coimmobilized cells had stable initial activity for at least one month.

Immobilization of Paracoccus denitrificans cells with polyelectrolyte complex and denitrifying activity of the immobilized cells

Abstract Whole cells from Paracoccus denitrificans IFO 12442 were immobilized with a polyelectrolyte complex composed of potassium poly(vinyl alcohol) sulfate (KPVS) and poly(diallyldimethylammonium chloride) (PDDA) by the following procedures: An excess of PDDA was first mixed with a cell suspension to aggregate cells, then KPVS was added to form a complex with excess PDDA and to entrap the aggregated cells. Electron microscopic analysis showed that the aggregated cells were entrapped or surrounded by an amorphous complex support. The rate of nitrate reduction or carbon consumption by the immobilized cells was almost the same as that by the free cells, as determined by anaerobic incubation using a non-growth medium containing KNO 3 as a substrate and potassium aspartate as a carbon source. The immobilized cells exhibited activity at pH 4, at which the free cells lost their activity. The initial activity of the immobilized cells remained stable for at least one month in a phosphate buffer with gentle stirring.

Continuous column denitrfication using polyelectrolyte complex-entrapped Paracoccus denitrificans cells

Abstract Whole cells from Paracoccus denitrificans IFO 12442 were immobilized with a polyelectrolyte complex consisting of poly(vinyl alcohol) sulfate and poly(diallyldimethylammonium chloride). Continuous denitrification using a column packed with the immobilized cells was carried out as follows: A non-growth medium containing KNO3 as a substrate and potassium aspartate as a carbon source was passed through the column under anaerobic conditions for about three months. It was found that the immobilized system remained stable during a period of more than two months, without the loss of activity or the leakage of the cells from the support.

Stoichiometric formation of poly-ion complexes between human carboxyhemoglobin and potassium poly(vinyl alcohol) sulfate

SummaryColloid titrations of human carboxyhemoglobin were carried out at different pH. The total number of basic groups in the hemoglobin was 95, as evaluated by the titration with potassium poly (vinyl alcohol) sulfate (KPVS). The value estimated was comparable with that obtained from the amino acid sequence of human hemoglobin. This finding indicates the stoichiometric salt-linkage formation between the basic groups in the hemoglobin and the KOSO3-groups in KPVS.

Flocculation of Aspergillus terreus with polyelectrolyte complex and production of itaconic acid with the flocculated mycelia

Abstract Mycelia from Aspergillus terreus K 26 were flocculated with a polyelectrolyte complex consisting of potassium poly9vinyl alcohol) sulfate (KPVS) and poly(diallyldimethyl-ammonium chloride) (PDDA) by three different methods: (a) PDDA was added into the broth obtained from precultivation of the hyphal inoculum in the presence of KPVS; (b) use of KPVS and PDDA was reversed from that in method a; (c) after the precultivation in the absence of the polymer, the mycelia were harvested, dispersed in 0.1 M phosphate buffer containing PDDA, then flocculated by addition of KPVS. The three types of the flocculated mycelia were investigated concerning growth and itaconic acid production in shake flask cultures. Viscosity and sedimentation were further examined to characterize the flocculated mycelial broths. A slight inhibition caused by flocculation on growth and acid production was observed at the beginning of repeated cultivation, but this was eliminated when cultivation in the fresh medium was repeated. There was no marked difference in the specific rates of acid production between fre and flocculated cells. Viscosity of the flocculated mycelial system was close to that of the medium, even while maintaining a cell concentration of 2 g/dl. The poor sedimentation of mycelia was favorably imporved with these flocculation methods, especially with methods b and c.

Study on adsorption of nonionic and cationic polymers on silica gel by using total organic carbon analysis

Abstract The adsorption behaviour of poly(ethylene oxide) and trimethylammonium glycol chitosan iodide from water onto silica gel is reported. A total organic carbon analytical method was employed to determine precisely the small quantity of polymer remaining after the attainment of adsorption equilibrium. The adsorption isotherms and the curves of equilibrium adsorption against pH were obtained and compared with the ionization properties of the silanol groups investigated by potentiometric titration. The results obtained are discussed in terms of the adsorption mechanism for nonionic and cationic polymers.

Selectivity of food bacteria for the growth of anaerobic ciliate Trimyema compressum

The anaerobic ciliate Trimyema compressum was cultivated on various food bacteria. Significant growth was observed when Lactobacillus sp., Escherichia coli, Enterobacter aerogenes, Desulfovibrio vulgaris, Methanoculleus bourgense, or Pelobacter propionicus cells were fed to the ciliates. The highest cell yield which we obtained was ca. 9,000 cells/ml when feeding D. vulgaris. However, no growth of the ciliates was observed on the culture with Clostridium novyi, Propionibacterium sp., Desulfobulbus propionicus, Methanobrevibacter arboriphilicus, Methanobacterium sp., Methanosarcina barkeri, or Methanothrix soehngenii cells. The ciliates produced acetate and methane as major end products in any cultures and small amounts of propionate, butyrate and hydrogen were also detected in some cultures. Physiological studies on the food bacteria which we tested indicated that the growth of T. compressum depended on the bacterial species, but there was no apparent correlation between the digestibility and the basic properties of those bacteria (i.e. size of the bacteria, gram-staining properties, susceptibility to the known lytic enzymes, Archaea or Bacteria).

Prevention of limiting substrate diffusion in an immobilized enzyme reaction system: Lectin-induced activation of gel-entrapped β-D-galactosidase

SummaryEscherichia coli β-D-galactosidase (EC 3.2.1.23) was entrapped in polyion complex-stabilized alginate gel beads together with a lectin fromRicinus communis (RCA1 lectin). The rate of entrapped enzyme-catalyzed hydrolysis of O-nitrophenyl-β-D-galactoside dramatically increased with an increase in lectin content, and at the maximum level of lection content the entrapped enzyme activity exceeded the native enzyme activity. A rapid decrease in the apparent Km was observed while increasing the lectin content, whereas the Vmax value varied insignificantly.

Change in the molecular weight distribution of poly(ethylene oxide) caused by the complexation with poly(acrylic acid)

Abstract The complexation between poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA) was made by using double the molar quantity of either polymer component at pH 2 where the resulting complex completely precipitates. After the removal of the precipitate, PEO or PAA remaining in the supernatant was subjected to gel permeation chromatography to investigate the change in the molecular weight distribution ( MWD ) caused by the complexation. No remarkable difference is observed in the MWD curves for PEO[1] ( M w =1.37 × 10 4 ) before and after the complexation with PAA[1] ( M w =1.10 × 10 3 ) and PAA[2] ( M w =4.16 × 10 5 ). However, the MWD curves of PEO[2] ( M w =1.26 × 10 5 ) and PAA[2] become shortened and shift to the low molecular weight side after the complexation with PAA[1] or [2] and PEO[2], respectively. This tendency is enhanced by increasing the complexation temperature. From these results, it is indicated that the complexation between PEO and PAA deals with an equilibrium reaction, and the equilibrium constant is dependent on the chain length of both polymer components and also on the complexation temperature.