- Purification and Properties of Extracellular Poly(3-hydroxybutyrate) Depolymerase Produced by Penicillium pinophilum
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Han, Jeen Sun , Son, Young Jong , Chang, Chung Soon , Kim, Mal Nam
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J. Microbiol. 1998;36(2):67-73.
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The extracellular poly(3-hydroxybutyrate)(PHB) depolymerase of Penicilliyum pinophilum ATCC 9644 was purified and characterized. When Penicillum sp. was grown in basal salt medium with PHB as a sole carbon source, higher temperature favored fungal mycelial growth (37℃>30℃>25℃), but enzyme production was lower ar 37℃ than at any other temperatures. The PHB depolymerase was purified using Sepharose CL06B and Sephacryl S0100HR column chromatography. The isolated enzyme was found to be composed of a single polypeptide chain with a molecular weight of about 35 kDa. The optimum condition for the enzyme was pH 6.0 and 50℃, Enzyme activity decreased sharply at temperatures above 50℃. The enzyme was found to be stable in the pH range of 2.0~10.0.1mM Fe^2+ reduced the enzyme activity by 55% abd 4 mM Fe^2+ inhibited it almost completely. The PHB depolymerase (10U) degraded 47% of solvent cast PHB film, while commercial lipase (1000U) of Rhizopus arrhizus degraded 10% of the same specimen, over a period of 48 hours.
- Induction of ethanol tolerance on the production of 17-ketosteroids by mutant of mycobacterium sp.
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Kim, Mal Nam , Kim, Eun Mi
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J. Microbiol. 1995;33(4):322-327.
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Tolerance of Mycobacterium sp. against organic solvents has been induced for the cholesterol side chain degradation by adding chemicals associated with synthesis of fatty acids or alcohols. Biotin of 300 ㎍/1 and 0.5% aqueous ethanol solution were optima for the enhancement of ethanol tolerance of the microorganism. The induction of ethanol tolerance by biotin was found to be due to increase of degree of unsaturation of the fatty acids in membranous phospholipid of the cell, especially due to increase of oleic acid content. However when 0.5% of ethanol was added for the ethanol tolerance induction, there was an ambiguous correlation between ethanol tolerance and degree of unsaturation of the fatty acids, in spite of the fact that the induction increased the content of unsaturated fatty acids. Addition of 0.5% of ethanol induced several ethanol shock proteins having molecular weight similar to that of heat shock proteins.
- Binding Sites for Lead Ion in Staphylococcus epidermidis
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Kim, Mal Nam , Sung, Hye Yoon
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J. Microbiol. 1995;33(3):228-233.
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As S. epidermidis cell was fractionated into cell wall, cell membrane, and cytoplasm, the cell membrane proved to be the most efficient absorbent for lead ion. Ultrasonication was effective, when the cells were treated during their exponential growth. The amount of the lead ion adsorbed in cell membrane decreased as hydrogen ion concentration of solution increased. Protein purified from the cell membrane showed higher adsorption capacity for the lead ion than peptidoglycan, teichoic acid from cell wall, or cell membrane lipid. Modification of carboxyl groups in the membrane protein with ethylenediamine and 1-ethyl-3-carbodiimide hydrochloride resulted in a considerable decrease of lead ion adsorption capability, suggesting that the main binding site for lead ion was the carboxyl groups of protein in cell membrane.
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