Setsuji Tone

Carbon dioxide fixation in batch culture of Chlorella sp. using a photobioreactor with a sunlight-cellection device☆

Abstract In a batch culture of Chlorella sp. using sunlight as a light source, the cell concentration reached a maximum of 150 mg dry cells dm −3 at 200 h. The mean rate of CO 2 fixation during the culture was 31.8 mg CO 2 dm −3 d −1 . The efficiency of conversion of energy to biomass was estimated as 4.3%.

Coalescence and breakup of bubbles in liquids

Abstract Coalescence and breakup in a swarm of bubbles were directly observed by using the high speed cinematography. It was designed so that three dimensional motion of bubbles could be continually followed. Influence of operating conditions and liquid properties on the frequencies of bubble passing, coalescence and breakup was examined. It was seen that there was the critical distance at which the leading bubble began to exert an noticeable influence on, the following one. The distance was about 3- to 4-fold diameter of the leading bubble. Coalescence was found to take place when more than about a half of the projected area of the following bubble was overlapped with that of the leading bubble at the critical distance. On the contrary, breakup occurred in the case of the overlapping less than about a half of the projected area of the following bubble. The increment of the following bubble velocity induced by the leading one was empirically correlated with the bubble distance and the angle between the straight line joining the centers of bubbles and the vertical axis. The Reynolds numbers had no appreciable effect on the velocity increment within the range examined.

Production and release of pigments by culture of transformed hairy root of red beet

Abstract Adventitious roots were induced from red beet ( Beta vulgaris L. cv. Detroit dark red) by infecting the plant with a soil bacterium, Agrobacterium rhizogenes . Based on analysis of opines which are uniquely produced in transformed hairy roots, the established clone was proved to be a transformed hairy root. In a shake culture of the beet hairy root clone with a liquid medium, it was found that significant amounts of pigments, mainly betanin and vulgaxanthin-I, were released into the medium by the cessation of culture shaking (temporary limitation of oxygen supply). The hairy root cells were capable of propagation even after the cells were subjected to shaking cessation. Repeated-batch culture of the beet hairy root was performed with the cell growth phases for 9 or 10 d and with pigment leakage phases during shaking cessation for 2 d, and more than 20% of the total intracellular pigments were recovered from the culture broth at a culture time of 35 d. The released pigments were confirmed to be substantially identical to those extracted from the hairy root and original plant cells of red beet.

The optical resolution of amino acids by plasma polymerized terpene membranes

Four kinds of terpenes, i.e. l-menthol, S-(−)-β-citronellol, [(1S)-endo]-borneol, and R-limonene, were fixed on a cellulose acetate membrane by plasma polymerization method at various periods of plasma irradiation. The fractional fixations of terpenes increased with increasing time of plasma irradiation. The optical resolutions of racemic tryptophan (dl-Trp) solutions were performed by the dialysis and the ultrafiltration using the plasma polymerized membranes. All the membranes were permeable with respect to the d-isomer tryptophan in in preference to the l-isomer. The larger value of separation factor was obtained at lower volume flux. The maximum value of separation factor obtained for dl-Trp was 9.5 at volume flux Jv=4.7 × 10−8 m s−1. The solute permeabilities and apparent viscous parameters were evaluated from the dialysis and ultrafiltration data, respectively. A linear relation between the solute permeability and the ratio of apparent viscous parameters was obtained. It is indicated that the strength of chemical interaction between the amino acid solute and the terpene fixed in the membrane has a high influence on the solute flow inside the membrane pore.

Influence of medium constituents on enhancement of pigment production by batch culture of red beet hairy roots

Abstract For the enhancement of pigment production by red beet hairy roots, the effects of medium constituents (Murashige-Skoog (MS) medium) on hairy root cultures were investigated in flasks. In a series of cultures using media with diluted medium components, it was found that phosphate was a key nutrient involved in pigment accumulation in the hairy roots, and that higher pigment contents in the roots were obtained at lower phosphate concentrations (range of 0–2.5 mol/m3). In an 18 d batch culture using phosphate-free medium, the total amount of pigment production was 4.8 times that obtained in a control culture using normal MS medium with 1.25 mol/m3 phosphate.

The optical resolution of amino acids by ultrafiltration membranes fixed with plasma polymerized l-menthol

Abstract l -Menthol was fixed on cellulose acetate membranes with pore diameters of 0.2, 0.45 and 0.8 μm by the plasma polymerization method at various times of plasma irradiation. The fractional fixation of l -menthol increased with increasing time of plasma irradiation, resulting in a decreasing pure water permeability of the membrane. The optical resolution of racemic tryptophan, phenylalanine and tyrosine was carried out by ultrafiltration using the plasma polymerized membrane, which was prepared by polymerizing l -menthol onto a cellulose acetate membrane with 0.2 μm membrane pore diameter exposed to plasma irradiation for 60 min. The membrane was permeable with respect to D-isomers of all three racemic amino acids in preference to L-isomers. The larger value of the separation factor was obtained at lower volume flux. The maximum value of the separation factor obtained for DL-Trp was 8 at Jv = 1.5 × 10−8 m · s−1.

Production and release of anthraquinone pigments by hairy roots of madder (Rubia tinctorum L.) under improved culture conditions

Abstract Carbon and nitrogen sources in the medium were selected for the culture of madder hairy roots producing anthraquinone pigments. The growth and pigment formation of the hairy roots were significantly enhanced by using modified Murashige-Skoog (MS) medium containing fructose and nitrate as the sole carbon and nitrogen sources, respectively, compared with those obtained in conventional MS medium with sucrose. Repeated-batch culture of the hairy roots was carried out, with pigment release into the medium obtained by means of O2 starvation treatment. In three pigment-release operations during 29-d culture, the total amount of released pigments was 21 mg/dm3, representing an average production rate of 0.72 mg/(dm3·d).

Valuation of growth parameters in monolayer keratinocyte cultures based on a two-dimensional cell placement model.

The influence of inoculum size on the growth of keratinocyte cells was investigated in a monolayer culture with serum-free medium. A growth model of cell placement was applied to the expression of the cell adhesion phase after the inoculation, lag phase, exponential growth phase, and stationary phase because of contact inhibition at high cell densities. Based on the model, the lag time until the onset of cell division was shortened in proportion to the logarithm of the inoculum cell size, resulting in the enhancement of overall cell propagation. It was verified that the proposed model is valid for the determination of the optimal inoculum size to realize the efficient growth of keratinocytes, indicating that the model is a useful tool to predict an optimal culture scheme for the production of skin grafts.

Reversible morphology change of horseradish hairy roots cultivated in phytohormone-containing media

Abstract Horseradish hairy roots were cultivated in the presence of phytohormones to achieve the processes of cell aggregate formation from the hairy roots and hairy root regeneration from the cell aggregates. In the process of cell aggregate formation, the combined addition 1.0 (or 2.0) mg/dm 3 NAA (1-naphthaleneacetic acid) and 0.5 mg/dm 3 BAP (6-benzylaminopurine) caused a significant change in morphology from hairy roots to cell aggregates. On the other hand, the formation and growth of hairy roots in the regeneration process were enhanced in the medium with the addition of NAA only. Effective regeneration of hairy roots from the cell aggregates was obtained in a culture with 2.0 mg/dm 3 NAA, and the number of regenerated roots was 26–38 per cm 2 -surface area of cell aggregate. It was found that the respective growth and peroxidase activity of roots repeatedly regenerated over three generations were comparable to those of the original hairy roots. This indicated that the hairy root properties were stably retained, even after a series of the cell aggregate formation and hairy root regeneration processes were conducted.

Characterization of pak-bung green hairy roots cultivated under light irradiation

Hairy roots of pak-bung turned green when cultured under continuous light exposure, and maintained their branched root morphology with the formation of chlorophyll and the development of a thylakoid membrane system in the cells. Green hairy roots cultivated under light exhibited increased root growth and enhanced activities of superoxide dismutase (SOD) and peroxidase (POD). A light intensity of 11.1 W/m2 using white fluorescent lamps was found to support good root proliferation and relatively high activities of SOD and POD. In cultures of green hairy roots at a light intensity of 11.1 W/m2, root growth, total SOD activity and total POD activity obtained on culture day 21 were 8.1 g-dry root weight/dm3, 18 × 104U/dm3 and 40 × 103U/dm3, respectively. In dark culture, the corresponding values obtained on culture day 21 were 3.8 g-dry root weight/dm3, 3.0 × 104U/dm3 and 9.5 × 103 U/dm3, respectively. It is concluded that exposure of the green hairy root culture to light caused an increased number of growing points at the root tip meristems due to the frequent branching of lateral roots.