Characteristics of catalase gene in Vibrio parahaemolyticus

• Main Authors: Shu-chuan Yu, 游淑娟
• Other Authors: Hin-chung Wong
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/07344310242647953388

碩士 === 東吳大學 === 微生物學系 === 102 === Vibrio parahaemolyticus is the most prevalent marine foodborne pathogen in Taiwan and has become a global concerned pathogen since the emergence of the pandemic O3:K6 strain in 1996. V. parahaemolyticus will encounter many extrinsic environmental stresses, and these stresses often cause or accompany with intrinsic oxidative stress. According to previous studies on the response of pathogens to a variety of stresses, the survival of pathogen is related to the effective control of reactive oxygen species (ROS) generated. V. parahaemolyticus has a variety of anti-oxidative proteins like catalase, superoxide dismutase, alkyl hydroperoxide reductase subunit C (AhpC) and other enzymes. They can remove and transform the ROS from cells. Catalase mainly transforms hydrogen peroxide to water and oxygen. V. parahaemolyticus has four catalase genes, VPA0305 and VPA1418 are the katE genes, VPA0453 and VPA0768 are the katG genes. This study targets on the katG genes. Using the in frame-deletion mutation method, V. parahaemolyticus 1173 VPA0453 mutant, VPA0768 mutant and VPA0453-VPA0768 double mutant were constructed, and complementary strains of the single mutation were also constructed. The relationship between the of katE gene and the two katG genes was explored. The normal shaking culture and static culture with low dissolved oxygen showed that growth of the single mutant and double mutant of katG were indifferent from that of the wildtype strain. In the presence of exogenous ROS (H2O2, t-BOOH, and cumene hydroperoxide), VPA1418 mutant showed enhanced sensitivity to H2O2, while the VPA0453 mutant and VPA0768 double mutant showed enhanced sensitivity to cumene. Growth and survival of these strains under low temperature ( 12℃or 4℃) were not significantly affected. In conclusion, the VPA1418 protein is probably the primary H2O2 scavenger at 37℃, the VPA0768 protein is probably the primary H2O2 scavenger in starvation. Whether single or dual stresses have shown these four genes are not major kat genes to help V. parahaemolyticus against oxidative stress, and from the double mutant strains tested showns that katE and katG plays different roles in growth phase and stresses. Our study suggest that catalase in the roles of stress, and catalase is regulated by OxyR, in oder to know more about the function of catalase, may need to explore the relevance of OxyR and catalase.