Free Yeast Cells Research Articles

Application of entrapped growing yeast cells to peptide secretion system

Efficient production of α-mating factor with immobilized growing Saccharomyces cerevisiae cells was examined in order to establish a secretion system for useful peptides using the α-mating factor secretion system. The free yeast cells produced α-mating factor into the cultured medium, but α-mating factor was gradually degraded in situ. Based on the criteria of α-mating factor productivity, cell growth in gels, cell leakage from gels, and mechanical strength of gels, a mixture of a hydrophilic neutral photo-crosslinkable resin prepolymer (ENT-2000) and an anionic prepolymer (ENTA-2) (8:2 by weight) was employed as gel material, among various kinds of natural and synthetic supports, to entrap the yeast cells. Anionic photo-crosslinkable resins selectively entrapped α-mating factor-degrading enzymes which were produced by the cells and degraded α-mating factor formed. The immobilized growing yeast cells could be used successfully for continuous production of α-mating factor in a packed column reactor for at least 30 days.

Immobilization of microbial cell and yeast cell and its application to biomass conversion using radiation techniques

The recent results of immobilization of cellulase-producing cells and ethanol-fermentation yeast by radiation were reported. The enzyme of cellulase produced by immobilized cells was used for saccharification of lignocellulosic wastes and immobilized yeast cells were used for fermentation reaction from glucose to ethanol. The wastes such as chaff and bagasse were treated by γ-ray or electron-beam irradiation in the presence of alkali and subsequent mechanical crushing, to form a fine powder less than 50 μm in diameter. On the other hand, Trichoderma reesei as a cellulase-producing microbial cell was immobilized on a fibrous carrier having a specific porous structure and cultured to produce cellulase. The enzymatic saccharification of the pretreated waste was carried out using the produced cellulase. The enhanced fermentation process to produce ethanol from glucose with the immobilized yeast by radiation was also studied. The ethanol productivity of immobilized growing yeast cells thus obtained was thirteen times that of free yeast cells in a 1:1 volume of liquid medium to immobilized yeast cells.

Ethanol production and the effect of porous polymer carriers on immobilized growing yeast cells by radiation-induced polymerization

As a means of producing ethanol as fuel from waste cellulose, yeast cells were immobilized by radiation-induced polymerization. Precultured yeast cells were incubated aerobically at 30°C for 24 h with porous polymer carriers prepared by radiation-induced polymerization at a low temperature. Yeast cells adsorbed on the surface of these porous carriers were immersed in monomer solution and were immobilized by radiation-induced polymerization of this monomer. The maximum ethanol productivity in an immobilized yeast cell system was found to be about 10 times greater than that in a free yeast cell system.

Growth of yeast cells immobilized with porous swelling carriers produced by radiation polymerization

A new method of immobilization of yeast cells for the advantageous growth of cells inside and on the surface of a polymer carrier by physical adsorption is proposed. Porous and swellable polymer carriers were prepared by radiation-induced polymerization at low temperature. These polymer carriers were incubated with yeast cells at 30°C under aerobic conditions. Yeast cells were adsorbed on the surface of polymer carriers and subsequently infiltrated the polymer carriers by multiplication. The ethanol productivity of immobilized growing yeast cells thus obtained was thirteen times that of free yeast cells in a 1:1 volume of liquid medium to immobilized yeast cells.

Immobilization of yeast cells by radiation-induced polymerization.

Radiation-induced polymerization method was applied to the immobolization of yeast cells. The effects of irradiation, cooling and monomer, which are necessary for polymerization, were recovered completely bu subsequent aerobic incubation of yeast cells. The ethanol productive in immobilized yeast cells increased with the increase of aerobic incubation period. The growth of yeast cells in immobilized yeast cell was indicated. The maximum ethanol productivity in immobilized yeast cell system was around three times as much as that in free yeast cell system.