• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.465-474
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• 1999

RNase activity of Saccharomyces cerevisiae ATCC 7754 was investigated to obtain strains with high ribonucleic acid (RNA) content. The yeast strain contained two RNase activities; an acidic RNase with a optima of pH $3{\sim}4$ and an alkaline RNase with a optima pH 9. The acidic RNase activity was inhibited by $0.08\;M\;HgCl_{2}$ most drastically. The alkaline RNase activity was inhibited by 2.0 M NaCl or KCl, while enhanced by addition of $0.05\;M\;CaCl_{2},\;0.02\;M\;ZnSO_{4},\;or\;0.008\;M\;HgCl_{2}$. Various mutants of Saccharomyces cerevisiae ATCC 7754 were isolated by ethylmethane sulfonate (EMS) treatment or $\gamma$-ray/ultra violet irradiation. Among the mutants that were sensitive to high concentration of KCl which inhibits alkaline RNase, B24 was selected for high RNA content per culture volume. Growth characteristics of the mutant were comparable to those of the mother strain with optimum growth at pH $4.5{\sim}5.5$. The mutant accumulated higher content of RNA than the mother strain when glucose was used as the carbon source. However, both growth rate and total RNA content of the mutant were higher in molasses medium than in glucose medium. RNA content of the mutant increased rapidly during the early stage of growth, and then decreased gradually until the culture reached stationary phase by a fed-batch culture in a 5 L jar fermenter. Maximal cell harvest and the final RNA content using the mutant B24 were 69.6 g/L culture broth and 19.8 g/100 g of the dry cell while those using the mother strain were 68 g/L culture broth and 16.1 g/100 g of dry cell, respectively.

• Journal of Life Science
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• v.32 no.12
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• pp.971-978
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• 2022

Sulfur-oxidizing, ammonium-oxidizing, and nitrogen-oxidizing media were used to isolate bacteria to degrade malodor gas effectively in piggery manure or soil. Twelve different strains were isolated: Paenibacillus amylolyticus, Rhodococcus jostii, Rhodococcus qingshengii, Rhodococcus opacus, Alcaligenes faecalis, Alcaligenes faecalis, Kastia adipate, Kastia adipata, Microbacterium oxydans, Halomonas campisalis, Acinetobacter oleivorans, and Micrococcus luteus. By inoculating each strain in the piggery liquid manure by 1%, the pH in most strain treatments was maintained at 8.0. Total bacterial counts were maintained at 7.3~7.9 log CFU/ml until 15 days, and then they dropped dramatically down to 5.1~5.5 log CFU/ml. On the 30th day, the treatment group inoculated with Rhodococcus opacus SK2659 showed a relatively high level of ammonium nitrogen removal, which was 39% of that of the control group. When Rhodococcus opacus SK2659 was inoculated, H2S concentration after 100 days was 3.23% compared with the control (no inoculation), suggesting that Rhodococcus opacus SK2659 is an excellent strain for removing malodor gas. The gas production of the treatments was lower than that of the control. The total accumulated amount of gas production in most strain treatments was a quarter of the gas production compared to the control throughout the experimental periods. Acinetobacter oleivorans SK2675 showed the lowest level at 12.39% compared to the control in gas production. In conclusion, the use of mixture strains, such as Rhodococcus opacus SK2659 and Acinetobacter oleivorans SK2675 isolated in this study could increase the efficacy of malodor gas reduction in the biological treatment of piggery manure.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.555-563
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• 1995

This study was performed to investigate the effect of Aloe arborescens on the cadmium toxicity in rats. Thirty male Sprague-Dawley strains were divided into five groups consisting of a control group, a cadmium treatment group and 3 aloe(0.5%, 0.75%, 1%) treatment groups and observed for 9 weeks. The weight increment of the cadmium and 0.75% aloe group was higher than that of the cadmium treatment group(p<0.01). The food intake did not show the consistency rule among the experimental groups and the decrement tendency of food intake affected by cadmium feeding group. The decrement tendency of water intake affected by cadmium appeared to be suppressed by aloe treatment, especially cadmium and 0.75% aloe treatment group showed the remarkable increment of water intake. The diet efficiency of the control group was the highest among the experimental groups and that of cadmium and 0.75% aloe group was higher than other aloe treatment groups. The weight of each organ did not show consistency among the experimental groups but only the testicle of cadmium and 0.75% aloe treatment group was heavier than that of the control group. The cadmium accumulation was high in order of kidney>liver>spleen>heart>lung>testicle>brain. The cadmium content of the cadmium treatment group was more than that of cadmium and 0.5% aloe group, cadmium and 0.75% aloe group, cadmium and 1% aloe group. The cadmium content of cadmium and 0.75% aloe group was the lowest among other aloe treatment groups. Therefore, cadmium and 0.75% aloe is the most recommendable aloe treatment to eliminate the cadmium accumulated in organ.