Fujimoto Takanori, Tsuchiya Yasuo, Terao Michinori, Nakamura Kazutoshi, Yamamoto Masaharu
Department of Community Preventive Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan.
Int J Food Microbiol. 2006 Nov 1;112(2):96-101. doi: 10.1016/j.ijfoodmicro.2006.06.003. Epub 2006 Oct 11.
Chitosan has been shown to have antibacterial activities on the growth of a wide variety of bacteria. Chitosan solution has been sold commercially for use as an antibacterial agent. Chitosan solution contains not only chitosan but also organic acids as solvents and desalted Japan Sea Proper Water (dJSPW). We aimed to clarify whether chitosan solution has antibacterial activity against bacteria invading bath water, and then to explore the causative factor among these ingredients. The antibacterial activity of full-strength chitosan solution and of 10(2)- and 10(4)-fold chitosan solution diluted with purified water was studied against Legionella pneumophila serogroups 1 (L. pneumophila SG1) and 6 (L. pneumophila SG6), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) for 7 days at 37 degrees C. To clarify the causative factor in the antibacterial activity against E. coli, the antibacterial activities of the full-strength and diluted chitosan solutions for 24 h were examined. L. pneumophila SG1 and SG6, and E. coli could not survive in the chitosan solution or in the 10(2)-fold dilute solution for over a day at 37 degrees C. The cells of S. aureus were found to have decreased more than 2.46 log cfu/ml after 1 day of incubation, not only in the chitosan solutions, but also in phosphate buffer solution as a control. No inhibitory effect of dJSPW on the growth of the bacteria was observed. The antibacterial activity of the chitosan solution was lower compared with those of the organic acids solutions, and it increased with decreasing pH value. We observed the antibacterial activity of chitosan solution against L. pneumophila SG1 and SG6, and E. coli, suggesting it may be due to the decreased pH value derived from organic acids rather than from chitosan itself or dJSPW.
壳聚糖已被证明对多种细菌的生长具有抗菌活性。壳聚糖溶液已作为抗菌剂进行商业销售。壳聚糖溶液不仅含有壳聚糖，还含有作为溶剂的有机酸和脱盐的日本海真水（dJSPW）。我们旨在阐明壳聚糖溶液对侵入浴水的细菌是否具有抗菌活性，然后探究这些成分中的致病因素。研究了用纯净水稀释的原液壳聚糖溶液以及10²倍和10⁴倍稀释的壳聚糖溶液对嗜肺军团菌血清型1（嗜肺军团菌SG1）和血清型6（嗜肺军团菌SG6）、大肠杆菌（E. coli）和金黄色葡萄球菌（S. aureus）在37℃下7天的抗菌活性。为了阐明对大肠杆菌抗菌活性的致病因素，检测了原液和稀释后的壳聚糖溶液24小时的抗菌活性。嗜肺军团菌SG1和SG6以及大肠杆菌在壳聚糖溶液或10²倍稀释溶液中于37℃下一天以上无法存活。金黄色葡萄球菌的细胞在孵育1天后不仅在壳聚糖溶液中，而且在作为对照的磷酸盐缓冲溶液中，其数量减少超过2.46 log cfu/ml。未观察到dJSPW对细菌生长有抑制作用。壳聚糖溶液的抗菌活性与有机酸溶液相比更低，并且随着pH值降低而增加。我们观察到壳聚糖溶液对嗜肺军团菌SG1和SG6以及大肠杆菌具有抗菌活性，这表明其抗菌活性可能归因于有机酸导致的pH值降低，而非壳聚糖本身或dJSPW。
