• The Korean Journal of Food And Nutrition
• /
• v.2 no.2
• /
• pp.14-20
• /
• 1989

A strain of Saccharomyces cerevisiae BY-366 was isolated to produce a strong sucrose-hydrolyzing enzyme. After entrapment of yeast cell invertase with alginate, enzymatic properties of immobilized cells were investigated. The results are as follows. 1. The optimum pH of invertase in immobilized cells and non- immobilized cells was 6.0 and 5.0, and pH stability of invertase in immobilized cells and non- immobilized cells was 6.0 and 5.0, respectively. 2 Activation energy of immobilized cells was 4.7 kcal/mol. 3 The immobilized preparation exhibited high resistance to heat and urea Induced denaturation. 4, The bead size less than 2 mm in diameter was desirable. 5. In spite of repeated use, the enzyme activity of immobilized cells was inhibited slightly in batch reaction, and a small column of the immobilized preparation could hydrolyze relatively high concentration of sucrose almost quantitatively to more than 6 days.

• Journal of the Korean Chemical Society
• /
• v.41 no.9
• /
• pp.483-487
• /
• 1997

The whole cells of Chromobacterium chocolatum was immobilized in the matrix of polyacrylamide and then used for the hydrolysis of dimethyl-cis-1,3-dibenzyl-2-oxoimidazolidine-4,5-dicarboxylate. This hydrolysis yielded the optically active monoester ( > 96% ee) which is useful as an synthetic intermediate of (+)-biotin. We have studied the optimum condition of hydrolysis by using immobilized cells under variable concentration of substrate, reaction time and pH levels. The activity of lipase in immobilized cell was retained for longer than 4 weeks. The best conversion yield of product was obtained when 2 g of wet cell was immobilized and then reacted with 200 mg of substrate at pH 7.

• Korean Journal of Food Science and Technology
• /
• v.9 no.3
• /
• pp.183-189
• /
• 1977

Studies were made of the continuous production of Pyridoxal 5'-phosphate (pyridoxal-p) on simultaneously immobilized cell column. Whole-cell of Pseudomonas polycolor having high activity of pyridoxine 5'-phosphate (pyridoxine-p) oxidase and Kloeckera sp. No. 2201 having high activity of catalase were used as the enzyme materials. The enzyme sources were entrapped in a polyacrylamide gel. Enzymatic properties of the simultaneously immobilized cells were investigated, comparing with those of the mixed whole-cells of the microorganisms. The simultaneously immobilized cells had higher enzyme activity than singly immobilized cells of Pseudomonas polycolor. From this result, the simultaneously immobilized pyridoxine-p oxidase-catalase system could be available to exert a protective effect upon the pyridoxine-p oxidase by destroying $H_2O_2$ which is a by-product of pyridoxine-p oxidation. The optimum pH was 9.0 for the immobilized cells and the whole-cells. The optimum temperature was $45^{\circ}C$ for the immobilized cells and $40^{\circ}C$ for the whole-cells. The pyridoxine-p oxidase of the immobilized cells were activated by $Hg^{++}$ and some SH-compounds.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.7
• /
• pp.1278-1284
• /
• 2016

Rhizopus chinensis cells immobilized on loofah (Luffa cylindrica) sponges were used to produce biodiesel via the transesterification of soybean oil. In whole-cell immobilization, loofah sponge is considered to be a superior alternative to conventional biomass carriers because of its biodegradable and renewable properties. During cell cultivation, Rhizopus chinensis mycelia can spontaneously and firmly adhere to the surface of loofah sponge particles. The optimal conditions for processing 9.65 g soybean oil at 40℃ and 180 rpm using a 3:1 methanol-to-oil molar ratio were found to be 8% cell addition and 3-10% water content (depending on the oil's weight). Under optimal conditions, an over 90% methyl ester yield was achieved after the first reaction batch. The operational stability of immobilized Rhizopus chinensis cells was assayed utilizing a 1:1 methanol-to-oil molar ratio, thus resulting in a 16.5-fold increase in half-life when compared with immobilized cells of the widely studied Rhizopus oryzae. These results suggest that transesterification of vegetable oil using Rhizopus chinensis whole cells immobilized onto loofah sponge is an effective approach for biodiesel production.

• Korean Journal of Microbiology
• /
• v.27 no.1
• /
• pp.70-76
• /
• 1989

Progestrone bioconversion by immobilized Aspergillus phoenicis was studied. Progesterone was converted into 11$\alpha$-hydroxyprogesterone and 3-minor byproducts. Whole cells of A. phoenicis were immobillized by enreappment with calcium-alginate, K-carrageenan, or polyacrylamide. Of these materials tested, cell immobilized in $Ca^{2+}$ -alginate gels showed the highest activity for 11$\alpha$-hydroxylation of progesterone. In the case of mycelia immobilized in $Ca^{2+}$-alginate, futher progressing hydroxylation of 11$\alpha$-hydroxyprogesterone was greatly reduced. Spores of A. phoenicis which were immobillized with $Ca^{2+}$-alginate and germinatedin situ for 25 hours showed higher 11$\alpha$-hydroxylase activity than those of entrapped whole mycelia and maintained initial enzyme activity for all 8 times of repeated use. After 16 times of reuse, the activity was declined 30% or more. When culture media and $Zn^{2+}$ were introduced into the reaction media, the activity of the immobilized mycelia which had been lowered due to many times of reuse was effectively reactivated.

• KSBB Journal
• /
• v.6 no.4
• /
• pp.351-361
• /
• 1991

This study is on the investigation of hydrogen production and substrate removal by photosynthetic bacteria. After using of Rhodospillum rubrum KS-301 and IFO 3986, which are photosynthetic bacteria as strains, R. rubrum KS-301 was turned out a better strain. And result of experiment in which glucose and sodium lactate, components of wastewater, were used limiting substrates, showed that the productivity of hydrogen was indifferent with the kind of substrates. In batch experiments using free cells and immobilized whole cells, the decrease in hydrogen productivity was observed in the latter case. From the results of these experiments, specific growth rate of cells, specific utilization rate of glucose, and specific production rate of hydrogen were calculated. And each rate was expressed in the form of Monod equation of which parameters were estimated. Also the optimum condition of hydrogen production for free cells was $30^{\circ}C$, pH 7, and 12,000 Lux, and the optimum immobilized condition was as follows: initial immobilized cell concentration 1.0g/L, sodium alginate concentration 2% and light intensity 12,000 Lux.

• Microbiology and Biotechnology Letters
• /
• v.14 no.4
• /
• pp.285-291
• /
• 1986

Immobilized Candida lipolytica cells were prepared by entrapping the whole cells in calcium alginate gel. To enhance citric acid productivity, immobilized cells were Incubated with activation medium in fluidized-bed reactors. When the activation was done in batch operation, maximum citric acid productivity appeared in a much shorter time than in continuous operation. Activated immobilized cells were enhanced about 10-fold in citric acid production relative to non-activated immobilized cells. The productivity of citric acid was also influenced by bead size. When Immobilized cells were reacted in a fluidized-bed reactor with the same quantity of cells, the citric acid productivity was increased as the bead size was decreased.

• Microbiology and Biotechnology Letters
• /
• v.20 no.6
• /
• pp.681-686
• /
• 1992

In the conversion of D.L-2-amino-$\Delta^2$-thiazoline-4-carboxylic acid(D,L-ATC) to L-cysteine using Pseudomonas sp. CU6. the effects of surfactants on whole cells and the stabilities of cellfree enzyme solution and continuous reactor packed with immobilized whole cells were investigated. The enzymatic reaction was little accomplished by whole cells without adding surfactants, whereas it was well carried out with SDS or Triton X-loo comparable to the case using cell-free enzyme solution. Enzyme activity of the cell-free solution was lost by 50% after 7 hours of storage at $30^{\circ}C$, but not at all under an anaerobic condition by sparging nitrogen gas. On the other hand. effect of nitrogen gas did not appear in a continuous reactor using immobilized whole cells, and hydroxylamine, an inhibitor of L-cysteine desulfhydrase, lowered the enzyme stability.

• Korean Journal of Food Science and Technology
• /
• v.24 no.5
• /
• pp.456-462
• /
• 1992

This study was performed to rapid fermentation from sardine hydrolyzate by using column reactor. The column reactor was constructed from three glass columns $(30cm{\times}5cm)$ and each column was packed with colloidal silica and sodium alginate (1:5) on which Pediococcus halophilus R-22, Saccharomyces rouxii R-60 and Candida etchellsii H-50, respectively, was previously fixed. At that time, optimal conditions for rapid fermentation were found the pH of 5.2, temperature of $30^{\circ}C$ and 10% NaCl. For rapid fermentation, immobilized whole cells of P. halophilus R-22, S. ruoxii R-60 and C. etchellsii H-50 packed the each column reactor were produced 0.75% lactic acid, 2.5% ethylalcohol and 18 mg/l 4-ethylguaiacol under the optimal conditions.

• Korean Journal of Food Science and Technology
• /
• v.12 no.4
• /
• pp.299-304
• /
• 1980

By using whole cells of Leuconostoc oenos ML-34 immobilized in polyacrylamide gel, deacidification of grape juice and wine was attempted. The immobilization did not destroy the original malo-lactic fermentation ability of the cells. However, the speed of malic acid decomposition by the immobilized cells was slow due to the slow transportation of the substrate through the gel layer. By reducing malic acid content in grape juice to a desired degree one may control the level of acid taste in wine fermented with the treated grape juice.