| Summary: | 碩士 === 國立高雄大學 === 生物科技研究所 === 93 === The strain of bacterium AB-10, which was isolated from soil outdoors, was able to produce antibiotic in the submerged culture. After the taxonomical investigation, the strain AB-10 was belonging to Arthrobacter sp.. It is rare to produce antibiotic by Arthrobacter sp.. The optimal medium composition for AB-10 strain to produce antibiotic in the submerged culture was found out as follows: 1% glycerol, 0.7% yeast extract, 0.5% malt extract and 0.06% MgSO4．7H2O. The batch culture was carried out at 30℃ for 12 hours on a rotary shaker at 150 rpm. The clear zone radius of AB-10 crude fermentation broth against Bacillus cereus was able to reach 9.0 mm. The antibiotic produced by AB-10 strain is classified as a growth associated with primary metabolite. It is different from most of the secondary metabolites of other strains. At the purification part, firstly, most protein of AB-10 crude fermentation broth was excluded by acetone precipitation. After charcoal suction twice and sephadex G-15 filtration, we could collect clearly purified product. The purified antibiotic was analyzed by thin layer chromatography with H2SO4 to express color; there existed the other impurity only. It indicated that most impurities were excluded after the purification process. The yield of the purified AB-10 antibiotic was 32.5%. The purified antibiotic still maintained 90% antibacterial activity at 60℃ for 30 minutes; 75% antibacterial activity at
80℃ for 30 minutes; however, only about 30% antibacterial activity over 90℃ for 30 minutes. The AB-10 antibiotic could not be extracted with organic solvents. It showed that AB-10 antibiotic was a polar compound. At antibacterial spectrum part, the Ab-10 antibiotic could inhibit Gram-positive bacteria (Bacillus and Staphylococcus), Gram-negative bacteria ( E. coli, Vibrio alginolyticus and Vibrio harveyi) and itself (Arthrobacter). However, the AB-10 antibiotic could not inhibit yeast (Candida albicans). The antibacterial effect of AB-10 antibiotic was static.
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