Antibacterial activity of chitosan against Helicobacter pylori

• Main Authors: Pei-Ling Hsieh, 謝佩伶
• Other Authors: Guo-Jane Tsai
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/26276165895161582520

碩士 === 國立臺灣海洋大學 === 食品科學系 === 93 === ABSTRACT Chitosan is the derivative of chitin via deacetylation. The antibacterial activity of chitosan increases with the increasing of acidic pH value. The urease production is an important criterion for Helicobacter pylori to survive in the stomach. The aim of this research is to investigate the effect of shrimp chitosan on the growth and urease production of H. pylori. The shrimp chitosan with 95% degree of deacetylation (DD95), and eight various strains of H. pylori, including three standard strains and five strains of patient isolates were used in this research. The effects of bacterial source, cell age, pH value and salts concentration on the antibacterial activity of DD95 against H. pylori were investigated. In addition, the effect of DD95 on the adherence of H. pylori to human intestinal carcinoma cell (TSGH9201), and the combining effect of DD95 with clinical antibiotic on the growth of H. pylori were studied. The antibacterial activity of DD95 on the growth and inhibiting urease production of various strains of H. pylori increases with increasing of DD95 concentration in the range of 1,000 ~ 4,000 ppm. In the presence of 4,000 ppm DD95, the survival rates for eight strains of H. pylori were 0.46 ~ 15.74%, and urease activity for these strains were decreased to 42.58 ~ 61.51%. Cell of H. pylori in the late log phase was most sensitive to DD95, with mid log phase being next and with stationary phase being the least. Adding NaCl (25mM and 100 mM) in medium can decrease the antibacterial activity of DD95, this decreasing effect was more obviously at the cell density of 104-105 CFU/mL than that at the lower density of 103 CFU/mL. The antibacterial activity of DD95 on H. pylori increases with the decreasing pH values from pH 8.0 to pH 2.0. The survival rates of H. pylori at pH 2.0 in the presence of DD95 were in the range of 0.53 ~ 1.17%, and their urease activity were decreased to 37.86 ~ 46.53%. In the presence of 100-200 ppm of amoxicillin, tetracycline or metronidazole, the counts for H. pylori could decreased by 1.47 ~ 4.81 log CFU/mL at both pH 2.0 and pH 6.0. Adding 4,000 ppm of DD95 into the antibiotic-containing medium, the count for H. pylori could be further decreased in total by 3.24~7.61 log CFU/mL. The DD95 could inhibit the adherence of H. pylori onto TSGH 9201 cell line, as evidenced by fluorescent microscopic observation.