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DIVERSITY OF FECAL PATHOGENS IN HAWAII’S COASTAL WATERS AND DETECTION WITH IMPROVED PERFORMANCE BY NEXT GENERATION SEQUENCING

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Title:DIVERSITY OF FECAL PATHOGENS IN HAWAII’S COASTAL WATERS AND DETECTION WITH IMPROVED PERFORMANCE BY NEXT GENERATION SEQUENCING
Authors:Saingam, Prakit
Contributors:Yan, Tao (advisor)
Civil Engineering (department)
Keywords:Environmental engineering
coastal water quality
diversity
fecal pathogen
FIB
show 1 moreimproved detection method
show less
Date Issued:2020
Publisher:University of Hawai'i at Manoa
Abstract:Among all pollutants in coastal waters, fecal pathogens have caused a lot of concerns due to their disease transmission risks. An investigation on the impact of pollution sources could provide guidelines for us to protect coastal water quality. However, the use of fecal indicator bacteria (FIB) in monitoring the presence of fecal pathogens can be misleading because of their prevalence in the environment. In the meantime, our understanding about the impact of storm water sources is still limited. While direct detection of pathogen has been an alternative monitoring system, the detection methods need to be improved. In order to address the above issues, I conducted four research projects, which will be shown and discussed in this dissertation.
In Chapter Two, the use of FIB in monitoring the quality of tropical urban marine estuary waters was investigated. The investigation included distribution of three FIB and four fecal pathogens at Ala Wai Canal (Oahu, Hawaii). The results showed that there was no correlation detected among the three FIB. Also, most of the tested typical fecal pathogens were not found. However, a pathogen and a marine microbe Vibrio parahaemolyticus was found prevalent but not correlated with the FIB. These findings indicated inconsistency between the FIB and fecal pathogens at a tropical urban marine estuary.
In Chapter Three, the immediate impact of major storms such as hurricanes on coastal waters was researched. The investigation included the prevalence and genotypes of FIB enterococci in coastal waters at Hilo bay immediately after the Hurricane Lane. Total enterococci across the investigated sites were detected with levels meeting the standard criteria and gradually decreased over time. However, the variation of enterococci concentrations and genotype distribution were more distinctive among sites. The findings uncover the immediate impact of a hurricane on temporal and spatial variation of coastal water quality.
In Chapter Four, the impact of hurricane on occurrence of pathogenic enterococci in Hilo bay water was examined. In this study, 49 enterococci isolates from Hilo bay were scrutinized for their species identification, virulence genes and antibiotic resistance susceptibility. Among the isolates, prevalence of E. faecalis and E. faecium/E. durans and their resistance to eight antibiotics were observed and four virulence genes were detected. This suggests the hurricane impact on the occurrence of pathogens and identified potential pathogens in coastal waters.
In Chapter Five, a novel PCR-NGS method of detecting pathogens in environmental samples was explored. This included tests on sensitivity and robustness against water samples. It will be shown that NGS can improve sensitivity of PCR and qPCR-based detection of Salmonella. Also, the PCR-NGS indicated that Salmonella can be successfully detected from coastal stream samples. These results demonstrated that PCR-NGS is a promising method of pathogen detection in environmental samples.
Overall, this dissertation sheds light on how we can enhance coastal water quality monitoring. The following topics were investigated and discussed: (i) evidences of misleading use of FIB in monitoring tropical urban marine estuary waters, (ii) impact of storm water on coastal water quality and occurrence of pathogen, and (iii) a novel approach of pathogen detection essential for the development of the pathogen-based monitoring system.
Pages/Duration:144 pages
URI:http://hdl.handle.net/10125/73318
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Civil Engineering


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