Kitani Yoichiro, Kikuchi Nobuyo, Zhang GuoHua, Ishizaki Shoichiro, Shimakura Kuniyoshi, Shiomi Kazuo, Nagashima Yuji
Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato, Tokyo 108-8477, Japan.
Comp Biochem Physiol B Biochem Mol Biol. 2008 Feb;149(2):394-400. doi: 10.1016/j.cbpb.2007.10.013. Epub 2007 Nov 9.
L-amino acid oxidase (LAO) shows broadly antibacterial activity against Gram-positive and Gram-negative bacteria by H(2)O(2) generated in the oxidative process of L-amino acids. However, LAO (termed SSAP) isolated from the rockfish Sebastes schlegelii skin mucus acted selectively on Gram-negative bacteria. Therefore, this study was undertaken to clarify the antibacterial action of SSAP as compared with H(2)O(2). SSAP inhibited potently the growth of Aeromonas salmonicida, Photobacterium damselae subsp. piscicida and Vibrio parahaemolyticus with a minimum inhibitory concentration (MIC) of 0.078, 0.16 and 0.63 microg/mL, respectively. H(2)O(2) inhibited the growth of both Gram-positive and Gram-negative bacteria with an MIC ranging from 0.31 to 2.5 mM. When SSAP was incubated with P. damselae subsp. piscicida and Escherichia coli, SSAP was demonstrated to bind to P. damselae subsp. piscicida but not to E. coli by Western blotting and LAO activity measurement. These results show that the bacteria binding activity may be involved in the bacterial cell selectivity of SSAP. Electron microscopic observation of A. salmonicida, P. damselae subsp. piscicida and V. parahaemolyticus revealed that the treatments with SSAP and H(2)O(2) induced cell surface damage to A. salmonicida, remarkable elongation of P. damselae subsp. piscicida bodies and pores into V. parahaemolyticus cells.
L-氨基酸氧化酶（LAO）通过L-氨基酸氧化过程中产生的H₂O₂对革兰氏阳性菌和革兰氏阴性菌具有广泛的抗菌活性。然而，从岩鱼许氏平鲉皮肤黏液中分离出的LAO（称为SSAP）对革兰氏阴性菌具有选择性作用。因此，本研究旨在阐明SSAP与H₂O₂相比的抗菌作用。SSAP能有效抑制杀鲑气单胞菌、美人鱼发光杆菌杀鱼亚种和副溶血性弧菌的生长，其最低抑菌浓度（MIC）分别为0.078、0.16和0.63μg/mL。H₂O₂对革兰氏阳性菌和革兰氏阴性菌均有抑制作用，MIC范围为0.31至2.5 mM。当SSAP与美人鱼发光杆菌杀鱼亚种和大肠杆菌一起孵育时，通过蛋白质免疫印迹法和LAO活性测定表明，SSAP能与美人鱼发光杆菌杀鱼亚种结合，但不与大肠杆菌结合。这些结果表明，细菌结合活性可能与SSAP对细菌细胞的选择性有关。对杀鲑气单胞菌、美人鱼发光杆菌杀鱼亚种和副溶血性弧菌的电子显微镜观察显示，用SSAP和H₂O₂处理会导致杀鲑气单胞菌细胞表面损伤、美人鱼发光杆菌杀鱼亚种菌体显著伸长以及副溶血性弧菌细胞出现孔洞。
