| Summary: | 博士 === 國立中興大學 === 獸醫學系暨研究所 === 107 === Shewanella infection is a zoonotic infectious disease which is one of the emerging sources of infection causing human infection within a consequence of global warming. The incidence of infections has been increasing with climate change. The majority of cases in clinics have underlying immunocompromising diseases and hepatobiliary diseases by soft tissue infection, bacteremia, and non-healing wound infection. The reason of Shewanellosis is underestimated because of the identification system which has limitation. Therefore, there is not much known about the mechanism of its pathogenesis and its adaptation to a special niche such as the hepatobiliary tract. In addition, the studies of Shewanell algae (SA) on environmental stress are rare. In this study, we collected 26 environmental strains of the genus SA, and recorded the phenotype of the strain under different environmental pressures to understand the tolerance of the SA strain to environmental stress factors in which to help to accurately control the risk of SA in food and human infections. The environmental stress factors including temperature and salinity tolerance which can mimic the stress factors for biliary system infections in patients with the hepatobiliary disease during ingestion raw seafood. Furthemore, the study is through whole-genome sequencing to understand the virulence genes and pathogenic potential of SA.
The isolation ratio of Shewanell algae is one quarter in all environment samples, The results showed the positive in API systems were gelatinase; the data showed negative reactions were indole production. In addition, S. algae can adapt wildly conditions which were 4~42 °C in experimental temperatures and 0-6% salinity. It appears to the key parameter is the temperature at 25°C and 37°C showed hemolysis. In another study, we isolated the sample of S. algae from the clinic. The genome of S. algae consists of a circular approximately 4.7 Mb chromosome with a GC content of 53.08%, within 4080 protein-coding sequences. It contains a number of candidate genes which were including htpB, exbBD, wecA, galU, adeFGH, and phoPQ regulon. These genes have been confirmed to be associated with bile adaption. Our results show that S. algae do not only have the ability to adapt to climate change but also adapt the human bile salt and can be the potential to cause diseases.
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