Hiroki Nakajima

Entrapment of Lavandula vera cells with synthetic resin prepolymers and its application to pigment production

SummaryCultured cells of Lavandula vera were entrapped with photosensitive synthetic resin prepolymers (PVA-SbQ). PVA-SbQ-entrapped cells grew well inside gel matrices and synthesized de novo blue pigments in the presence of l-cysteine as an inducer. The entrapped cells were superior to calcium alginate-entrapped cells judging from cell growth and total pigment productivity. Release of the pigments, which were almost insoluble in water, from the gels was markedly enhanced by the increase in hydrophilicity of the cell-entrapping gels. The entrapped cells could be used repeatedly for the pigment production.

Continuous production of oxytetracycline by immobilized growing Streptomyces rimosus cells

SummaryStreptomyces rimosus cells were immobilized with urethane prepolymers and used in the production of oxytetracycline. Based on the criteria for oxytetracycline productivity, cell growth in gels, cell leakage from gels and mechanical strength of gel, a hydrophilic prepolymer, PU-1, the main chain of which was polyethylene glycol (molecular weight, approximately 1500) was employed as gel material among 11 kinds of urethane prepolymers. Use of glucose-free medium for cultivation of PU-1-entrapped cells increased the production rate of oxytetracycline and minimized cell leakage from the gels. When the gel-entrapped cells lost activity, treatment of the cell-entrapping gels with saline or 70% ethanol resulted in recovery of the oxytetracycline productivity. Continuous oxytetracycline fermentation using PU-1-entrapped growing cells was successfully achieved in air-bubbled reactor for at least 35 days with reactivation of the cells.

Entrapment of Lavandula vera cells and production of pigments by entrapped cells

Abstract Finely suspended cells of Lavandula vera were obtained by cultivating the cells in the presence of 50 mM CaCl 2 and entrapped homogeneously in gels formed from natural polysaccharides, agar, alginate and κ-carrageenan. The gel-entrapped cells grew well inside the gel matrices, the growth being confirmed by the increases in oxygen uptake, cell number and chlorophyll content. Blue pigments were synthesized de novo in the presence of l -cysteine by the gel-entrapped cells as well as by the free counterparts. Calcium alginate gel-entrapped cells were employed for the repeated production of the pigments for over 7 months by alternating growth and production phases. Entrapment with adequate gels stabilized markedly the viability and the pigment productivity of the plant cells.

Continuous production of l-serine by immobilized growing Corynebacterium glycinophilum cells

SummaryAuxotrophic mutant cells of Corynebacterium glycinophilum with high l-serine production activity were immobilized by entrapment with various gel materials, such as synthetic prepolymers and natural polysaccharides. The entrapped cells were used for estimation of l-serine productivity in a medium supplemented with glycine as a precursor. Based on the above criteria, including cell growth in gels and cell leakage from gels, calcium alginate was the most suitable gel material. Continuous l-serine fermentation with calcium alginate-entrapped growing cells was successfully achieved in an air-bubbled reactor for at least 13 days.

Influence of carbon source on pigment production by immobilized cultured cells of Lavandula vera

Abstract A portion of glucose yielded through hydrolysis of sucrose was consumed by immobilized cultured cells of Lavandula vera for pigment production when sucrose was employed as a carbon source under the limitation of nitrogen sources. Glucose was readily incorporated into the immobilized cells for pigment production, while the uptake of fructose was delayed compared with that of glucose. This time lag of fructose uptake resulted in the delayed induction of pigment production. Use of glucose as a carbon source accelerated pigment production and increased pigment productivity in successive batches of the incubation.

Enhancement of Pigment Productivity of Immobilized Cultured Lavandula vera Cells by Limitation of Nitrogen Sources

Abstract Cultured cells of Lavandula vera entrapped with a photosensitive synthetic resin prepolymer (PVA-SbQ) produced blue pigments in the presence of l -cysteine as an inducer. The type of nitrogen sources in the culture medium greatly influenced the production of pigments. In the absence of an ammonium type nitrogen source, the induction of pigment synthesis by l -cysteine was observed in successive batches of the incubation without intermittent activation of the cells in the absence of l -cysteine. The pigment productivity of the entrapped cells was remarkably enhanced in the improved production medium containing potassium nitrate as the sole nitrogen source.

Production of daunorubicin by immobilized growing Streptomyces peucetius cells

SummaryStreptomyces peucetius cells were immobilized by entrapment in calcium alginate and a photosensitive synthetic polymer, and used for the production of daunorubicin (daunomycin), which is known to be an antitumour reagent. The use of cultivation media removed insoluble components in a natural medium prevented rapid decrease in daunorubicin titer after maximum production. These entrapped cells could be used at least five times for repeated daunorubicin production; the total cultivation period was 45 days.

Development of a simple non-freezing method to preserve cultured plant cells

Abstract A simple procedure to preserve suspended or immobilized plant cell culture (Lavandula vera and Nicotiana tabacum) has been developed. L. vera cells were stored under dark and cool (4°C) conditions n sealed glass bottles. When medium was removed from the system with the immobilized cells, enhanced viability after long-term preservation was obtained. The cells were able to grow successfully after storage for 30 d, and incubation for only 10 d after storage was enough to recover the oxygen uptake activity to the level of that of the original cells. L. vera cells retained the ability to synthesize blue pigments, specific secondary metabolites of the cells, even after storage. Entrapment in calcium alginate beads was effective to preserve the cells more than 50 d. The importance of air supply in preservation was strongly suggested. N. tabacum cells could also be preserved for 30 d.

Construction of a Photo-Controllable Enzyme Reaction System by Co-Immobilization of an Enzyme and a Semiconductor

TiO2, one of the semiconductors, could oxidize NADH to NAD+ on irradiation with ultraviolet light. A co-immobilization system of alcohol dehydrogenase and TiO2, entrapped in calcium alginate, catalyzed acetaldehyde formation from ethanol through recycling of NAD+, which was dependent on irradiation. Irradiation at intervals made it possible to control the enzyme reaction. Furthermore, the immobilized enzyme-semiconductor system gave more stable response for a long period than the non-immobilized free system under repeated irradiations. These results demonstrate that photo-controllable enzyme reaction systems with stable responses might be constructed by various combinations of co-immobilized enzymes and semiconductors.

Application of the freeze-blast method to disruption of cultured plant cells.

Abstract The freeze-blast method with a ‘Cryo-Clean Blaster (CCB)′ was applied to disrupt liquid-cultured plant cells of Lavandula vera L 10 4-2154. Recovery of peroxidase and chlorophylls a and b by this method was relatively higher than that obtained by the glass beads method. Under hypertonic conditions, chloroplasts were also isolated without lysis of the cells.