• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.1
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• pp.20-24
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• 2000

A 7-week growth trial was conducted to investigate the effects of yeasts (Kluyveromyces fragilis and Candida utilis) with or without cell wall chemical treatment (protoplasted) in formulated diets on growth and body composition of larval ayu (Plecoglossus altivelis). Three replicate groups of ap average weighing 100 mg were fed diets containing each level ($5{\%}$) of K. fragilis, protoplasted K. fragilis, C. utilis, protoplasted C. utilis or brewer's yeast as an additive. Survival rate of fish fed the diet containing protoplasted K. fragilis, C. utilis or protoplasted C. utilis was higher than that of fish tea the control diet (P<0.05). Body weight .gain of fish fed the diet containing protoplasted K. fragilis was higher than that of fish fed the control diet (P<0.05). Crude protein and ash contents of Ssh were not significantly affected by the different dietary yeasts (P>0.05), On the other hand, crude lipid content of fish fed the diet containing K. fragilis, protoplasted K. fragilis or brewer's yeast was higher than that of fish fed the control diet (P<0.05). Amino acids composition of fish was not significantly affected by the different dietary yeasts (P>0.05), except aspartic acid. The results suggest that protoplasted K. fragilis as an additive in micro-formulated diet can improve weight gain and body quality of larval ayu.

• Journal of Aquaculture
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• v.13 no.1
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• pp.55-62
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• 2000

A 10-week feeding trial was conducted to investigate the effects of several yeasts with or without chemical treatment (protoplasted) in formulated diets on growth and body composition of juvenile abalone(Haliotis discus hanai). There replicate groups of the abalone average weighing 210 mg were fed one of eight isonitrogenous (30%) and isolipidic (4.4%) diets containing 3% Kluyveromyces fragilis protoplasted K. fragilis Candida utilis protoplasted C. utilis, Saccharomyces cerevisiae protoplasted S. cerevisiae or brewer's yeast. In addition these formulated diets were compared with commercial diet. Survival rate and proximate analysis of soft whole body of abalone were not significantly affected by the different dietary yeasts and commercial diet (P>0.05) Body weight gain and soft body weight control diet and diets containing S. cerevisiae or brewer's yeast (P<0.05) Shell length of abalone fed yeast and commercial diet (P<0.05) Th results suggest that protoplasted K. fragilis as an additive in this formulated diet can improve weight gain of abalone.

• Journal of Life Science
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• v.8 no.2
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• pp.197-202
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• 1998

The cell of Kluyveromyces fragilis yeast, which is worthy of an algal substitute, was disrupted by a chemical treatment to increase the digestion of filter-feeders that yeasts are fed to. The optimum conditions of the chemical treatment were obtained by incubating yeasts at 3$0^{\circ}C$ for one hour after treated by 1 M of Na$_{2}$-EDTA that was dissolved in 0.2 M of Tris-buffer and by 0.3 m of 2-mercaptoethanol. The percentage of protop[last production was about 30%. The percentage could be doubled by the pretreatment of three times of 30 seconds sonication.

• Korean Journal of Microbiology
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• v.23 no.4
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• pp.309-314
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• 1985

Autoxotrophic mutants of a cellulolytic baterium Cellulomonas sp. CS 1-1 were grown at $30^{\circ}C$ for 6hr using a complete medium containing 0.5M sucrose and for another 90 min after addition of 0.3 U/ml penicillin G, and were protoplasted by 0.2mg/ml lysozyme for 2hr. Prototrophic recombinants were obtained at the rates of $10^{-3}$ to $10^{-5}$by fusing the protoplasts in the presence of 40% polyethyleneglycol3350. Nystatin could be used to eliminate fungal contamination during the regeneration of the plotaplasts.

• Korean Journal of Microbiology
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• v.28 no.4
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• pp.304-310
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• 1990

The conditions for protoplasts formation and regeneration of thermophilic anaerobic C. thermocellum and C. thermohydrosulfuricum were determined under the anaerobic growth conditions. The cells of C. thermocellum in initial exponential growth phase were identified to be the most suited for protoplast formation. The optimal conditions for protoplast formation were found to be at $37^{\circ}C$ for 2 hours with 0.5 mg/ml of lysozyme in TMG buffer (pH7.5). On the other hand, C. thermohydro-sulfuricum grown in the same medium but excluding glycine was optimally protoplasted at the same conditions but with 0.2 mg/ml of lysozyme. The protoplasts of both strains only subjected to lysozyme treatment of the short time were satisfactorily regenerated after 7-10 days incubation at $60^{\circ}C$ in regeneration medium containing 0.3-0.4 M sorbitol, 0.5% casamino acid, and high concentration of $CaCl_{2}$ and $MgCl_{2}$. The regeneration frequencies of the protoplasts of C. thermocellum and C. thermohydrosulfuricum were found to be very low level of $4.85{\times}10^{-3}$ and $4.23{\times}10^{-2}$, respectively. The nonregenerated L-form cells were also observed inregeneration medium together with regenerated cells.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.6
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• pp.791-797
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• 1999

This study was conducted in order to evaluate nutritive values of yeasts (Kluyveromyces fragilis and Candida utilis) according to growth stages (early log phase, log phase, stationary phase and death phase) and chemical treatment of their cell wall, Proximate, amino acids, fatty acids and nucleotides composition of the yeast samples was determined. Crude protein content was high in K. fragilis ($48\~59\%$) compared to C. utilis ($26\~43\%$). Crude lipid and fiber contents of the yeasts were below than $1.6\%$ and $3.3\%$, respectively. Conposition of aspartic acid, glycine, proline, leucine, Iysine and valine of K. fragilis were higher than those of C. utilis, and glutamic acid and arginine of C. utilis were higher than those of K. fragilis. Proximate and amino acids composition was not siginificantly influenced by growth stage of the yeasts. Major fatty acids of the yeasts in all growth stages were $C_{10-18}$. $C_{16-18}$ contents were relatively high in the early log or log phase and $C_{10-12}$ contents were relatively high in the stationary or death phase. However, n-3 highly unasturated fatty acids (C$\ge$20) in the all growth stages were not observed. This result indicated that these yeast strains could not be adequate as a dietary lipid source for marine fish. Composition of nucleotides and their related compounds (ATP ADP AMP, IMP and inosine) in the early log phase yeasts were lower than those in the log, stationary and death phase yeasts.