Rhizopus japonicus의 Lipase에 關한 硏究 = Studies on the Lipase of Rhizopus japonicus

다국어 초록 (Multilingual Abstract)

A powerful lipase producing strain S-62 was selected by extensive screening test of molds isolated from the various sources. These experiments were conducted to identify the selected strain and to investigate the conditions of the lipase production and the characteristics of the purified enzyme. The results obtained were as follows;
1. The selected strain was identified as Rhizopus japonicus according to the classification method of Rhizopus genus by Inui, Takeda & Iizuka.
2. The optimum initial pH was 6.8-7.0 and the optimum temperature was in the vicinity of 27℃, for the enzyme production.
3. Soybean meal and ammonium sulfate were the most effective in the lipase production as organic and inorganic nitrogen sources, respectively.
4. The lipase production was strongly inhibited, when added as carbon sources xylose, glucose, fructose, galactose, maltose, soluble starch, and dextrin causing the lowering of pH of the media during culture. Sucrose did not inhibit lipase production, but not caused any effect when added.
5. K_(2)HPO_(4) as phosphate salt and MgSO_(4)·7H_(2)O as magnesium salt were the most effective in the lipase production.
6. The addition of olive oil, soybean oil, and coconut oil respectively increased the enzyme production and especially 1% olive oil increased it by 50%.
7. The enzyme production increased slightly on the addition of yeast extract to 0.05-0.07%.
8. The optimum composition of the medium for the lipase production by the selected strain was in the composition of soybean meal 2%; K_(2)HPO_(4) 0.5%;(NH_(4))_(2)SO_(4) 0.1%; MgSO_(4)·7H_(2)O 0.05%; yeast extract 0.05%; olive oil 1%. The maximum production of lipase was attained by the incubation for 48hrs under the optimum incubation condition.
9. The purified enzyme was obtained with the specific activity 126.5/㎎ protein, or about 45 times as strong as the original activity and the yield of 4.2%, by means of salting out with ammonium sulfate (0.5% saturation) of the crude enzyme solution, desalting by Sephadex G 25, CM cellulose column chromatography and concentration by Sephadex G 25, and gel filtration by Sephadex G 75.
10. In the acrylamide gel disc electrophoresis of the purified enzyme appeared the main band and two obscure ones on both side of the main band, which indicated that the enzyme was considerably purified compared with its crude enzyme solution, even if it is not referred to as a pure protein.
11. The optimum pH for the enzyme action was 6.8, the stable pH range 5.0-8.0, and the optimum temperature 35℃. The purified enzyme was stable below 45℃ and inactivated abruptly above 45℃.
12. Coconut oil, castor oil, and palm oil were most favorably hydrolyzed by the purified enzyme, whereas olive oil and soybean oil were silghtly less than the former three, and Tween 80 was hydrolyzed only 30% compared with coconut oil.
13. The purified enzyme was outstandingly activated by Ca^(++) and Mg^(++), whereas it was strongly inhibited by Hg^(++) and Fe^(+++).

목차 (Table of Contents)

• Ⅰ. 緖論
• Ⅱ. 硏究史
• Ⅲ. 實驗方法
• Ⅳ. 實驗結果및 考察
• 1. 菌株의 分離와 優秀菌株의 同定
• 2. lipase의 生産條件
• 3. lipase의 精製및 純度
• 4. 精製酵素의 特性
• Ⅴ. 摘要
• 參考文獻
• SUMMARY